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Synthesis of the Thioborate Crystal ZnxBa2B2S5+x (x ≈ 0.2) for Second Order Nonlinear Optical Applications
Abstract
Thioborate materials have been considered for novel infrared nonlinear optical (NLO) materials having large optical nonlinear properties combined with favorable laser damage thresholds and wide transmission ranges from the visible to the mid-infrared regions. In this work, known and new thioborate materials have been investigated that have the potential to overcome the low laser damage thresholds of the NLO chalcopyrite sulfide materials such as AgGaS2 without losing their large nonlinear properties and wide transmission ranges. A new thioborate phase, polycrystalline ZnxBa2B2S5+x (x ≈ 0.2), has been prepared by the reaction of the metal sulfides and B2S3 glass in carbon crucibles sealed inside evacuated silica tubes. It crystallizes in the tetragonal system with unit cell parameters of a = 4.762(4) Å and c = 24.020(7) Å and is based on isolated (BS3)3- structural units. The second harmonic generation (SHG) efficiency determined on powders of ZnxBa2B2S5+x (x ≈ 0.2) is 50 times larger than that of α-SiO2. The infrared spectrum shows transparency from 2.5 to 10 μm with absorption bands around 12 μm related to the vibration modes of (BS3)3- units. The UV−visible spectrum shows that it is transparent in the visible region down to 350 nm, which is a large improvement over the absorption edge of AgGaS2 at 490 nm.
... On the other hand, the synergetic collaboration of different NLO functional motifs may contribute to new NLO materials with adjustable activities. The studied NLO-active chalcogenoborates are very rare 28 and only include Zn x Ba 2 B 2 S 5+x , 29 Ga or In and Q = S or M = M′ = In and Q = Se; however, there are none with M = M′ = Ga and Q = Se. Third, in light of the absence of some members it is difficult to obtain the complete chemical rule behind this family. ...
A series of pentanary chalcogenoborates (A3X)[InB12(InQ4)3] (A = K, Rb, Cs; X = Cl, Br, I; Q = S, Se) were obtained by high-temperature solid-state reactions. These salt-inclusion chalcogenides crystallize in the hexagonal space group P6322, a type of Kleinman-forbidden noncentrosymmetric structure. Their structures feature a [InB12(InQ4)3] open framework built by InQ6 octahedra and InQ4 tetrahedra consolidated B12 cluster, which accomodates octahedral cavities for XA6 units. They are second-harmonic generation active, and their optical properties were studied experimentally and theoretically. This work can evoke more interest in chalcogenoborate-based second-order nonlinear optical materials.
... The infrared spectra result (Fig. 4) [24,25] . The infrared spectra prove the presence of lighter element boron. ...
A new zero-dimensional (0D) thioborate Ba9B3GaS15 has been discovered by conventional high-Temperature solid-state reaction. The compound crystallizes in orthorhombic space group Pbca with a = 8.4759(8), b = 22.266(2), c = 31.426(3) A, V = 5931(2) A3, Z = 8, Mr = 1819.11, Dc = 4.075 g/cm3, μ = 13.684 mm-1, F(000) = 6320, S = 1.034, (δρ)max = 5.039, (δρ)min =-5.409 e/A3, the final R = 0.0362 and wR = 0.1053 for 19243 observed reflections with I > 2δ(I). The structure is constructed by discrete [BS3]3-trigonal planes and isolated [GaS4]5-tetrahedra with Ba2+ and isolated S2-filled among them. The UV-Vis-near-IR spectrum reveals a wide band gap of 3.15 eV that agrees with the electronic structure calculation.
Thioborates are considered new potential mid-infrared nonlinear optical (NLO) crystals with wide bandgap and large second-harmonic generation (SHG) coefficients. Despite the fact that many rare-earth thioborates are structurally non-centrosymmetric, their...
The Boron-Chalcogen Mixture method was used to obtain single crystals of the previously extremely difficult to synthesize lanthanide orthothioborates to investigate their structures and their structurally connected optical behavior, such as second harmonic generation. Using a combined halide and polychalcogenide flux, the BCM method yielded single crystals of LnBS3 (Ln = La, Ce, Pr, Nd), which are isostructural and crystallize in the non-centrosymmetric space group, Pna21. Second harmonic generation measurements confirmed the expectation that LaBS3 would exhibit a strong SHG response, measured at 1.5 × KDP.
Both borates and sulfides are important inorganic multifunctional materials. Encouraged by this background, thioborates attract considerable interest. However, their investigations are highly hindered by the scarcity of the available ones and the synthetic difficulty of the new ones. Here, we report a new thioborate KEu2In3B12S13 (1), which was obtained via a facile solid-state reaction in KI flux. It crystallizes in the trigonal R3̄m structure, and the three-dimensional structure features a six InS6 octahedron consolidated B12 icosahedron built {[In3B12S12]5-}∞ polyanionic framework and a unique In6S6 12-membered ring, representing a new type of compound. The B12S12 cluster is also different from the other known thioborates. The structural chemistry, optical and magnetic properties, as well as theoretical calculations of 1 were systematically studied. This study not only provides a new type of thioborate but also makes a breakthrough in the synthesis of thioborates.
Ba2BS3Cl and Ba5B2S8Cl2 have been synthesized by using PbCl2 as the flux and source of halogen. The two compounds show 3D network structures built by isolated [BS3] units with different...
Ultraviolet nonlinear optical (UV NLO) crystals are the key and basic materials for solid-state lasers. Phosphates as UV NLO crystals are limited in practical applications due to their weak second-harmonic generation (SHG) response. In this work, two non-centrosymmetric pyrophosphates of K3SrBi(P2O7)2 and Rb3SrBi(P2O7)2 were successfully synthesized by a high-temperature solution method. Systematic property measurements show that they both have short UV cut-off edges (~ 240 nm) and large SHG responses (4 × KDP and 2.1 × KDP for K3SrBi(P2O7)2 and Rb3SrBi(P2O7)2, respectively). Thus, they are both promising UV NLO candidates. Especially, K3SrBi(P2O7)2 shows the strongest SHG response in the family of A3BBi(P2O7)2 (A = K, Rb, B = Sr; A = Rb, Cs, B = Ba, Pb), which is about twice higher than that of isomorphic Rb3SrBi(P2O7)2. The study of structure-property relationship shows that the synergistic effect of P2O7 and BiO6 polyhedra are the main contribution on their excellent NLO, and better orientations of P2O7 and larger distortion of BiO6 units play important roles for the enhanced SHG response of K3SrBi(P2O7)2.
An excellent nonlinear optical (NLO) material should satisfy many critical requirements simultaneously. How to balance all the requirements is a challenge, as those cause contradictory demands on structural attributes. Here, we use a high entropy strategy to integrate the advantages of ZnSe for a large NLO coefficient and planar [InSe3]3- functional motif for phase matching. The resulting Ba6In6Zn4Se19 crystal shows excellent comprehensive NLO properties, i.e. a large effective NLO coefficient (2×AgGaS2), a high laser induced damage threshold (LIDT, 15.5×AgGaS2), a wide transmission range (0.52-21 μm), and an increased birefringence (Δn=0.098) for phase matching. Theoretical calculations indicate that the planar [InSe3]³⁻ is an effective NLO functional motif for tuning birefringence and the “cocktail effect” realized via the high entropy strategy is important to improve the overall NLO performance. This study provides a promising way of developing new NLO materials with excellent comprehensive performance.
Trigonal planar units with high physicochemical stability and large polarizability anisotropy are one kind of promising fundamental building blocks (FBBs) for constructing novel nonlinear optical (NLO) materials. Though great achievements have been made in ultraviolet/deep ultraviolet (UV/DUV) region with trigonal planar units, little attention has been paid to them in infrared band owing to the lack of enough representatives. In this work, [AgSe3] and [HgSe3] are rationally proposed as NLO active FBBs. Besides, Ag6HgMSe6 (M = Si, Ge) are screened out by combined density functional theory calculations and experiments as new type IR NLO materials. Experiments demonstrate both Ag6HgSiSe6 and Ag6HgGeSe6 show strong second harmonic generation (SHG) responses, valuable phase–matchable features and congruent–melting thermal behaviors. Moreover, the great contributions of the trigonal planar units have also been discussed in detail.
The development of infrared (IR) laser still lacks the efficient IR frequency-conversion materials. Borates as critical nonlin-ear optical (NLO) materials have been achieved the deep UV to visible laser output, but they cannot satisfy the demand of IR laser limited by their low IR absorption edges. With this in mind, thioborates are focused by the optimization-based ani-onic group design through the replacement of B-O with the B-S units, which could extend the IR transmission range and simultaneously maintain the large bandgaps as well as strong NLO effects. Herein, the millimeter-level crystals of thioborate BaB2S4 compound (1.5 × 1.5 × 0.5 mm3) as a new breakthrough of IR NLO material with the suitable balance among wide bandgap (3.55 eV) and large second harmonic generation (SHG) effect (0.7 × AgGaS2), as well as high laser damage thresh-old (8 × benchmark AgGaS2) were successfully synthesized and exhibit good air stability, which breaks the prejudice of thi-oborates in air-sensitivity. These high laser damage threshold and unexpected air stability suggest the potential of thiobo-rates applied as IR NLO materials. Remarkably, the theoretical calculation also analyzes the specific contribution for per-formances on the thioborates basic building units ([BS3]3- and [BS4]5-), the result indicates that the [BS3]3- group can be ex-pected as the excellent gene to design new promising IR NLO candidates.
Nonlinear optical crystal of fluosilicate Na2SiF6 is synthesized via hydrothermal method and its structure is determined by single crystal X-ray diffraction (XRD). The space group of Na2SiF6 is P321 with cell parameters a = 8.8715(3) Å, c = 5.0484(5) Å, Z = 3, V = 344.09(4) Å3. The properties of the crystal are measured by powder XRD, infrared (IR) spectroscopy, Ultraviolet(UV)−Visible(Vis)−Near-Infrared (NIR) diffuse reflectance spectroscopy, thermogravimetric (TG) and differential scanning calorimetry (DSC) analysis. The band gap calculated using CASTEP is 7.41 eV, indicating that the cut-off edge of the Na2SiF6 crystal can be down to deep-UV energy region. The First-principles studies were performed to elucidate the structure-property relationship of Na2SiF6.
A series of new pentanary inorganic supramolecular sulfides (A3X)[MB12(MS4)3] (A = Na, K, Cs; X = Cl, Br, I; M = Ga, In, Gd) have been synthesized using high-temperature solid-state reactions. They crystallize in the noncentrosymmetric hexagonal space group P6322. Their structures feature MS4 tetrahedra saturated B12 icosahedron, and the latter is also alternatively connected with MS6 octahedron via sharing face to form a chain. [(K3I)2+]n polycationic chains fill in the 1D channels of the 3D open-framework {[MB12(MS4)3]2–}n. A discussion about their structural chemistry is also presented. Their second-order nonlinear optical (NLO) properties are calculated using Material Studio software, and the results show that this series of thioborates show tunable NLO properties.
Mid-infrared (IR) nonlinear optical (NLO) materials with high performance are vital to expanding the laser wavelengths into the mid-IR region, and have important technological applications in many civil and military fields. For the last two decades metal chalcogenides have attracted great attentions since many of them possess large NLO effect, wide transparent range, moderate birefringence and high resistance to laser damage. However, the discovery of superior mid-IR NLO metal chalcogenides is still a big challenge mainly attributed to the difficulty of achieving the good balance between NLO effect and laser damage threshold (LDT). In this review, the metal chalcogenides are catalogued according to the different types of microscopic building blocks. These groups include triangle planar units, tetrahedral metal-centered unit, polyhedra with second-order John-Teller (SOJT) cations, and polyhedra with stereochemically active lone electron pairs (SALP) cations, rare-earth (RE) cations and/or halogen anions. The determinations of these microscopic structures on mid-IR NLO properties in metal chalcogenides are summarized and analyzed combined with available experimental data and first-principle calculations. From the deduced structure-property relationship, the searching directions for new metal chalcogenides that have good mid-IR NLO performances, especially for achieving the balance between large NLO effect and high LDT, are discussed.
Nonlinear optical (NLO) crystal materials with good performance are urgently needed. Various compounds have been explored to date. Metal chalcogenides and borates are common sources of potential NLO materials with desirable properties, particularly in the IR and UV regions, respectively. However, these two types of crystals have their specific drawbacks. Thioborates, as an emerging system, have unique advantages by combining the merits of borates and sulfides, i.e., the high laser damage thresholds and rich structural diversity of borates with large optical nonlinearity and the favorable transparency range of sulfides. However, only a limited number of thioborates are known. This paper summarizes the known thioborates according to structural motifs that range from zero-dimension to three-dimension, most of which are formed by sharing corners of the basic building units (BS3)(3-) and (BS4)(5-). Although nearly one-third of the known thioborates are noncentrosymmetric, most of their properties, especially their NLO behaviors, are unexplored. Further attempts and additional investigations are required with respect to design syntheses, property improvements and micro-mechanism studies.
An alkali metal selenite chloride, Rb2SeOCl4·H2O, has been hydrothermally synthesized and structurally characterized. It is the first example of an alkali metal selenite halide in the literature. The compound crystallizes in the noncentrosymmetric (NCS) space group, Cmc21(36), of the orthorhombic system with a = 10.342(3) Å, b = 10.124(3) Å, c = 9.158(3) Å, and α = β = γ = 90°. The anionic [SeOCl4](2-) groups are arranged in the crystal in nearly the same direction, giving rise to a relatively large macroscopic dipole moment, causing the compound to display second harmonic generation (SHG) eight times as strong as that of KDP, measured using the Kurtz-Perry method on powders. First-principle density functional theory (DFT) calculations were carried out to interpret the relationship between the crystal structure and properties.
A new mercury selenide BaHgSe2 was synthesized. This air-stable compound displays a large nonlinear optical (NLO) response and melts congruently. The structure contains chains of corner-sharing [HgSe3]4- anions in the form of trigonal planar units, which may serve as a new kind of basic functional group in IR NLO materials to confer large NLO susceptibilities and physicochemical stability. Such trigonal planar units may inspire a path to finding new classes of IR NLO materials of practical utility that are totally different from traditional chalcopyrite materials.
Mid-IR second-order NLO crystal is indispensable in the frequency conversion applications in the mid-IR region. Compared with DUV and UV/Vis/near-IR NLO crystals, practical mid-IR NLO crystals are relatively rare, and many of them are still at the stage of laboratory research. This chapter reviews the recent progress on the mid-IR NLO crystals, which mainly includes growing the classical mid-IR NLO crystals into large high-quality ones or into quasi-phase-matching structures that are suitable for the laser devices by various growth methods and exploring new potential mid-IR NLO crystals by introducing new design and synthesis strategies. Recent mid-IR NLO crystals can be divided into four categories, i.e., classical binary and ternary metal pnictides and chalcogenides, quaternary metal chalcogenides, binary and ternary metal halides, and different-bond-type hybrid compounds that contain at least two types of obviously different chemical bonds in the crystal structures. Metal pnictides and chalcogenides have got much attention on growing large crystals. Different-bond-type hybrid is a new family of mid-IR NLO materials, and many of them were found in the last decade. In metal halide system, both progress in growing large crystals and discovering new ones have been made.
The most advanced UV-vis and IR NLO materials are usually borates and chalcogenides, respectively. But thioborates, especially thio-borometalates, are extremely rare. Here, four new such compounds are discovered by solid state reactions representing 0D structures constructed by isolated BQ3 trigonal planes and discrete MQ3 pyramids with Ba(2+) cations filling among them, centrosymmetric monoclinic P21/c Ba3(BS3)1.5(MS3)0.5 (M = Sb, Bi) 1, 2 with a = 12.9255(9), 12.946(2) Å; b = 21.139(2), 21.170(2)Å; c = 8.4194(6), 8.4207(8) Å; β = 101.739(5), 101.688(7)°; V = 2252.3(3), 2259.9(3) Å(3) and noncentrosymmetric hexagonal P6̅2m Ba3(BQ3)(SbQ3) (Q = S, Se) 3, 4 with a = b = 17.0560(9), 17.720(4) Å; c = 10.9040(9), 11.251(3) Å; V = 2747.1(3), 3060(2) Å(3). 3 exhibits the strongest SHG among thioborates that is about three times that of the benchmark AgGaS2 at 2.05 μm. 1 and 3 also show an interesting structure relationship correlated to the size mismatching of the anionic building units that can be controlled by the experimental loading ratio of B:Sb. Syntheses, structure characterizations, and electronic structures based on the density functional theory calculations are reported.
We describe the preparations of inorganic noncentrosymmestry (NCS) chalcogenides and their infrared nonlinear optical properties. We present a reasonable synthesis of inorganic NCS compounds by thinking of genetic development processes of a living organism. The basic unit having NCS structure is selected as a gene of NCS materials. The NCS compounds will be obtained from NCS genetic development of normal growth. The genetic development will be an alienation process of growth if the NCS compound is not formed by NCS gene. The NCS genes of (SnS4) and (Sn2S3) were normal development to obtain the NCS crystal of Ba7Sn5S15. The NCS genes of (BiS5) and (InS4) were development into a compound of Ba2BiInS5 keeping in NCS structure. Both of them, the Ba2+ ions are a charge-compensating agent. The NCS crystals SnGa4Q7 (Q = S, Se) were obtained by NCS genes of (GaQ4) and (SnQ4). However, the centrosymmetry (CS) compound of Ba6Sn7S20 was obtained because the developments of NCS genes of the (SnS4) and (SnS5) alienate from the normal process of growth. For NCS compounds, we have searched their nonlinear optical (NLO) properties of micro-crystals (powders) and electronic origin of NLO response. The intensity of second harmonic generation (SHG), laser-induced damage threshold (LIDT), and infrared transparency were measured, and the conversion efficiency, figure of merit (FOM), and energy band structure were calculated for these NCS compound materials. It is found that the NCS materials of SnGa4Q7 (Q = S, Se) appear with large conversion efficiencies, high damage threshold and wide transparencies in the mid-infrared region. And, the study of micro-mechanism elucidate that the stereochemically active lone-pair electrons of Sn2+ can significantly improve the polarity of the [SnQ4] gene. Large NLO responses of them originate from the covalent interactions of Sn−Q and the cooperative effects of polarities between the genes [SnQ4] and [GaQ4]. It is also found that the Ba7Sn5S15 material is type-I phase-matchablility, and that the SHG conversion efficiency and FOM is about twice of that of AgGaS2 at the saturated particle size (particle size of 150−212 μm).
A series of new metal chalcogenides Ba4CuGa5Q12 (Q = S, S0.75Se0.25, Se) were synthesized using KBr flux at 750 °C. The three compounds are isostructural and adopt the noncentrosymmetric space group P4̅21c. Crystal data are as follows: Ba4CuGa5S12, 1, a = 13.040(1) Å, c = 6.304(1) Å, and Z = 2; Ba4CuGa5S9.00(1)Se2.92(1), 2, a = 13.1585(2) Å, c = 6.3520(2) Å, and Z = 2; Ba4CuGa5Se12, 3, a = 13.598(1) Å, c = 6.527(1) Å, and Z = 2. The three-dimensional framework in 1 is constructed by infinite columns ∞1[CuGa4S10]7– that surround the discrete GaS4 tetrahedra situated on a 4̅ axis. The discrete GaS4 tetrahedra on the stacking (112) planes and canted oriented edge-sharing CuS4 tetrahedra within the columns may account for the occurrence of strong second-harmonic generation (SHG) responses. Compounds 1–3 are transparent in the mid-infrared range and have the absorption edges at 2.82, 2.05, and 1.45 eV, respectively. The new nonlinear optical (NLO) materials are type-I nonphase matching at 693 nm and display strong SHG intensities that are 2.7, 2.6, and 1.1 times that of AgGaSe2 at 808 nm. Raman spectroscopic characterization of the compounds is reported.
Reaction of 2.5-dicarboxy-1-methylpyridinium (DCMP) chloride and Zn(NO3)2·6H2O in the presence of NaHCO3 in water gave an expected acentric diamondoid network [Zn(DCMP)2] with a three-fold interpenetration. With long Zn–Zn separations, very large cavities are formed within each diamondoid network with high propensity to interpenetration, which makes it show a promising non-linear optical property with SHG efficiency approximately 7 times higher than that of potassium dihydrogen phosphate (KDP). The design strategy of ligand through methylation of the corresponding pyrdinecarboxylic acid can be extended to other widely used carboxylic acids, more importantly, to lead to an unsymmetric bifunctional bridging ligand, which is essential for generating polar solids.
A new thio-germanium sulfide Li2Ga2GeS6 has been synthesized for the first time and its structure was found to be isomorphous with AgGaGeS4, which is well-known as a promising infrared NLO material. The host structure is built of GaS4 tetrahedra linked by corners to GeS4 tetrahedra to create a 3D framework forming tunnels along the c-axis, in which the Li+ ions are located. The second harmonic generation (SHG) efficiency determined on powders of Li2Ga2GaS6 is 200 times larger than that of α-SiO2. Unlike AgGaS2 and AgGaGeS4, Li2Ga2GeS6 was observed to be very stable under prolonged Nd:YAG 1.064 μm laser pumping, indicative of a large improvement in laser damage threshold. This new material could supplant Ag phases in the next generation of high-power infrared NLO applications.
Two new different-bond-type hybrid compounds, (Hg6P4Cl3)(PbCl3) (1) and (Hg23P12)(ZnCl4)6 (2), with supramolecular interactions between host and guest moieties, which based on metal-pnicogen, pnicogen-pnicogen, and metal-halogen bonds were obtained by solid-state reactions. Compounds 1 and 2 show large second-harmonic-generation (SHG) activity and are transparent in the wide mid-IR region, providing an effective route for searching new IR nonlinear-optical material systems by combining two or more different bond types with no IR absorption within a single compound through supramolecular assembly. Theory predications based on first-principles calculations are also performed on the SHG properties of 1 and 2.
Two new mid-infrared transparency compounds, centric Ba(2)BiGaS(5) (1) and acentric Ba(2)BiInS(5) (2), were synthesized from a high-temperature solid-state reaction in evacuated closed silica tubes. Their crystal structures were determined by a single crystal X-ray diffraction method at 293 K. The results of crystal structure solution indicate that compound 1 crystallizes in the centrosymmetric space group Pnma with trans- (1)(∞)[BiGaS(5)](4-) chain structure, while compound 2 crystallizes in the noncentrosymmetric polar space group Cmc2(1) with cis- (1)(∞)[BiInS(5)](4-) chain structure. Two types of lone-pair electrons alignment fashions within (1)(∞)[BiMS(5)](4-) chains result in destructive (for 1) or constructive (for 2) dipole moments, as illustrated in the crystal structures and the partial electron density maps based on the first-principles electronic structure computations. Powder second-harmonic generation (SHG) experiments with a 2.05 μm pumping laser show that the SHG efficiency of the polar compound 2 is approximately 0.8 times that of KTiOPO(4) (KTP) reference. Furthermore, SHG signal intensity measurements using different size particles of powder samples indicate that compound 2 can also achieve type I phase-matching, which makes the compound promising for practical applications.
Two new quaternary thioborates, PbSbBS(4) and PbBiBS(4), have been synthesized from solid-state reaction methods at temperatures from 1073 to 1123 K in evacuated sealed quartz tubes. The crystal structures have been determined by means of single crystal X-ray diffraction and they both crystallize in the P2(1)/m space group of the monoclinic system with a = 5.9532(18) Å, b = 6.2031(13) Å, c = 9.250(3) Å, β = 108.200(16)°, Z = 2 for PbSbBS(4) and a = 5.971(10) Å, b = 6.273(9) Å, c = 9.132(15) Å, β = 107.75(2)°, Z = 2 for PbBiBS(4), respectively. The two compounds are isostructural and both constructed with the infinite one-dimensional [MBS(4)](2-) (M = Sb or Bi) chains as building blocks, which are composed of [BS(3)](3-) trigonal plane units with [MS(3)](3-) (M = Sb or Bi) trigonal pyramids connected alternatively through corner-sharing along the crystallographic b axis. Two adjacent [MBS(4)](2-) chains are further bridged by the intermediate Pb(2+) cations, forming a novel S-shaped Pb-[MBS(4)] dimeric chain structure. In addition, first-principles electronic structure calculations based on the density functional theory (DFT) were performed on compound PbSbBS(4), indicating that the compound belongs to direct semiconductor with a band gap of 1.803 eV, which is in good agreement with the experimental value estimated from the UV-Vis diffuse reflectance spectroscopy.
Two new quaternary thioborate compounds with strongly one-dimensional growth, BaSb(BS(3))S and BaBi(BS(3))S, have been synthesized using the conventional solid state reaction method in closed tubes at 1100 K. The single crystal X-ray diffraction analysis has shown that compound BaSb(BS(3))S crystallizes in space group Pnma of the orthorhombic system with unit cell parameters of a = 9.6898(15) A, b = 6.2293(13) A, c = 11.670(2) A, V = 704.4(2) A(3), and Z = 4, while compound BaBi(BS(3))S crystallizes in space group C2/m with unit cell parameters of a = 14.9890(17) A, b = 6.2457(6) A, c = 7.5591(9) A, beta = 101.604(5) degrees , V = 693.19(13) A(3), and Z = 4. The two compounds both crystallize in the structure of infinite one-dimensional chains with [BS(3)](3-) trigonal plane coordination alternately bridged by [MS(3)](3-) (M = Sb, Bi) trigonal pyramids through sharing two sulfur atoms along the crystallographic b axis. First-principles electronic structure calculations performed with the density functional theory (DFT) method show that the calculated band gaps of BaSb(BS(3))S and BaBi(BS(3))S are 2.29 and 2.16 eV, respectively, which are in good agreement with the experimental values estimated from UV-vis absorption spectra using the Kubelka-Munk equation, and the observed absorption peak is assigned as charge transfers from S-3p states to Sb-5p (Bi6p) states.
A novel chiral open-framework structural hexanary chalcogenoborate, (K(3)I)[SmB(12)(GaS(4))(3)] (1), was obtained by a facile approach using boron as the reducing reagent; it shows weak SHG-activity and is transparent in the mid-IR region.
Four new quaternary isostructural rare-earth thiosilicates, ZnY(6)Si(2)S(14) (1), Al(0.50)Dy(3)(Si(0.50)Al(0.50))S(7) (2), Al(0.38)Dy(3)(Si(0.85)Al(0.15))S(7) (3), and Al(0.33)Sm(3)SiS(7) (4), crystallized in the chiral and polar space group P6(3), have been prepared by a facile synthetic routine. Compounds 1-3 show strong second harmonic generation effects at 2.1 um with the intensities of 1, 2, and 3 being about 2, 2, and 1 times that of KTP (KTiOPO(4)), respectively. The calculated band structure of 1 implies that the optical absorptions of BLn(6)M(2)Q(14) and ALn(3)MQ(7) family compounds are mainly ascribed to the charge transitions from Q-p to Ln-4f (4d for Y) states. Compounds 2-4 exhibit antiferromagnetic-like interactions.
An achiral nonlinear optical chromophore with a "remote functionality" that can act as a ligand is developed on the basis of 4-nitroaniline derivatized with pyridine. The molecules are assembled through complexation with simple achiral zinc(II) salts and the H-bond network mediated by the counterions, to generate noncentrosymmetric materials exhibiting optical second harmonic generation (SHG). The crystal structures of the new complexes are determined; the counterion strongly influences the ligand orientations and lattice structure. SHG of the microcrystalline materials is investigated. Correlation between the structure and SHG is rationalized using semiempirical quantum chemical estimation of the hyperpolarizabilities of molecules and molecular clusters. The metal complexation plays a significant role in molecular assembly but affects the SHG very little, enabling simplified analysis of the bulk property in terms of molecular responses. Organization of remote functionalized molecules by metal ion complexation thus offers a convenient approach to the rational design of quadratic NLO materials.
Reaction of Na(2)Mo(VI)O(4) x 2H(2)O with (NH(4))(2)SO(3) in the mixed-solvent system H(2)O/CH(3)CN (pH = 5) resulted in the formation of the tetranuclear cluster (NH(4))(4)[Mo(4)(VI)SO(16)] x H(2)O (1), while the same reaction in acidic aqueous solution (pH = 5) yielded (NH(4))(4)[Mo(5)(VI)S(2)O(21)] x 3H(2)O (2). Compound {(H(2)bipy)(2)[Mo(5)(VI)S(2)O(21)] x H(2)O}(x) (3) was obtained from the reaction of aqueous acidic solution of Na(2)Mo(VI)O(4) x 2H(2)O with (NH(4))(2)SO(3) (pH = 2.5) and 4,4'-bipyridine (4,4'-bipy). The mixed metal/sulfite species (NH(4))(7)[Co(III)(Mo(2)(V)O(4))(NH(3))(SO(3))(6)] x 4H(2)O (4) was synthesized by reacting Na(2)Mo(VI)O(4) x 2H(2)O with CoCl(2) x 6H(2)O and (NH(4))(2)SO(3) with precise control of pH (5.3) through a redox reaction. The X-ray crystal structures of compounds 1, 2, and 4 were determined. The structure of compound 1 consists of a ring of four alternately face- and edge-sharing Mo(VI)O(6) octahedra capped by the trigonal pyramidal sulfite anion, while at the base of the Mo(4) ring is an oxo group which is asymmetrically shared by all four molybdenum atoms. Compound 3 is based on the Strandberg-type heteropolyion [Mo(5)(VI)S(2)O(21)](4-), and these coordinatively saturated clusters are joined by diprotonated 4,4'-H(2)bipy(2+) through strong hydrogen bonds. Compound 3 crystallizes in the chiral space group C2. The structure of compound 4 consists of a novel trinuclear [Co(III)Mo(2)(V)SO(3)(2-)] cluster. The chiral compound 3 exhibits nonlinear optical (NLO) and photoluminescence properties. The assignment of the sulfite bands in the IR spectrum of 4 has been carried out by density functional calculations. The cobalt in 4 is a d(6) octahedral low-spin metal atom as it was evidenced by magnetic susceptibility measurements, cw EPR, BVS, and DFT calculations. The IR and solid-state UV-vis spectra as well as the thermogravimetric analyses of compounds 1-4 are also reported.
de Bislang kennt man das Auftreten von sowohl trigonal-planar als auch tetraedrisch koordiniertem Bor in einer Kristallstruktur nur aus der Bor-Sauerstoff-Chemie. Mit dem neuen Bariummetathioborat BaB2S4 stellen wir nun zum erstenmal eine Verbindung vor, deren Anionenstruktur aus zu Ketten kondensierten BS3- und BS4-Einheiten im Verhältnis 1 : 1 besteht, die entlang der c-Achse verlaufen. BaB2S4 wurde aus Bariumsulfid, amorphem Bor und Schwefel in einer Hochtemperatur-Feststoffreaktion bei 800 °C dargestellt und kristallisiert im monoklinen Kristallsystem in der Raumgruppe Cc (Nr. 9) mit den Gitterparametern a = 6, 6465(5) Å, b = 15, 699(1) Å, c = 6, 0306(5) Å, β = 110, 96(1)°, Z = 4.
Abstract
en BaB2S4: The first non-oxidic Chalcogenoborate with Boron in a trigonal-planar and tetrahedral Coordination
Hitherto we know boron in a trigonal-planar and a tetrahedral coordination within one crystal structure from boron oxides in various compounds. With the novel bariummetathioborate BaB2S4 we now report a crystal structure containing BS3 and BS4 units in the ratio 1 : 1 forming infinite chains along [001]. BaB2S4 was synthesized in a solid state reaction at a temperature of 800 °C from barium sulfide, amorphous boron and sulfur and crystallizes in the monoclinic space group Cc (no. 9) with the following lattice parameters: a = 6.6465(5) Å, b = 15.699(1) Å, c = 6.0306(5) Å, β = 110.96(1)°, Z = 4.
The 'subsolidus' phase relations at room temperature in the system CaO-B2O3-BaO are investigated. Specimens of various compositions were prepared from appropriate ratios of CaCO3, B2O3, and BaCO3, and fired from 780° to 1040°C according to their melting points. There are three ternary compounds in this system. The crystal structures of these compounds were determined by X-ray diffraction (XRD). CaBa2(BO3)2 and Ca5Ba2B10O22 are monoclinic structures. The lattice constants a = 14.221 angstrom, b = 4.569 angstrom, c = 11.926 angstrom, β = 99.947°, and V = 763.4 angstrom3 for CaBa2(BO3)2 and a = 15.714 angstrom, b = 6.184 angstrom, c = 10.204 angstrom, β = 93.954°, and V = 989.29 angstrom3 for Ca5Ba2B10O22 are obtained. The third compound, CaBa2(B3O6)2, is isostructural with the high form of BaB2O4 with lattice constants a = 7.167 angstrom and c = 35.298 angstrom. Powder second harmonic generation efficiencies of these ternary compounds were measured using a homemade apparatus.
An experimental technique using powders is described which permits the rapid classification of materials according to (a) magnitude of nonlinear optical coefficients relative to a crystalline quartz standard and (b) existence or absence of phase matching direction(s) for second‐harmonic generation. Results are presented for a large number of inorganic and organic substances including single‐crystal data on phase‐matched second‐harmonic generation in HIO3, KNbO3, PbTiO3, LiClO4·3H2O, and CO(NH2)2. Iodic acid (HIO3) has a nonlinear coefficient d 14∼1.5×d 31 LiNbO3. Since it is readily grown from water solution and does not exhibit optical damage effects, this material should be useful for nonlinear device applications.
Cs2B2S4 (I41/acd; a = 7,270(1) Å, c = 35,737(7) Å; Z = 8; Subzelle: I4/mmm; a′ = 5,141(1) Å, c′ = 17,868(4) Å, Z = 2) wird durch Reaktion von Caesiumsulfid Cs2S mit amorphem Bor und elementarem Schwefel im Verhältnis 1:2:3 bei einer Reaktionstemperatur von 600°C mit anschließendem Tempern dargestellt. Die Kristallstruktur besteht aus molekularen, planaren [B2S4]2−-Einheiten mit extrem gespannten [B2S2]-Vierringen, zwischen denen sich die neunfach koordinierten Alkalimetallkationen befinden. Das Strukturmotiv zweier kantenverknüpfter BS3-Gruppen wird hier erstmals in der Chemie der Thioborate isoliert beobachtet, ist jedoch als Baustein des polymeren Bor-Schwefel-Gerüsts im B2S3 bekannt.Cs2B2S4 – A Derivative of the Dimeric Metathioboric AcidCs2B2S4 (structure: I41/acd; a = 7.270(1) Å, c = 35.737(7) Å; Z = 8; substructure: I4/mmm; a′ = 5.141(1) Å, c′ = 17.868(4) Å, Z = 2) is prepared by the reaction of cesium sulfide with stoichiometric amounts of boron and sulfur (effective molar ratio M:B:S = 2:2:4) at 600°C and subsequent annealing. The crystal structure contains isolated [B2S4]2− groups consisting of four-membered B2S2 rings with two exocyclic sulfur atoms on each of the boron atoms. The cesium cations are nine-coordinate between these rings. The structural feature of two edge-sharing BS3 groups forming an isolated anion appears for the first time in thioborate chemistry, although it is known as a part of the polymeric network in B2S3.
Second order nonlinear optical coefficient and energy gap data collected from the literature have been classified and are organized by plotting their respective values. The two-dimensional plots indicate that both large energy gap and small ζ(2) and small energy gap and large ζ(2) are highly correlated. It was found that a single law expression cannot represent the data well for energy gaps over the entire range from 0 to 10 eV. Therefore a fit for narrow energy gap (0 < 1 eV) and for wide energy gap (E > 1 eV) materials are provided. A corresponding trend and fitting strategy is also demonstrated for the figure of merit (FOM) which is used to rank materials for wavelength conversion efficiency. Results of the analysis are used to estimate the second order nonlinear optical properties and conversion efficiencies of several less-well-known materials. Trend analysis suggests that ordered GaInP2 would be exceptional as an E-O waveguide material and that the FOM of AgGaTe2 is 3.3 times that of AgGaSe2 and that crystals of HgGa2Se4 and TexSe(1 − x) alloys should be of distinct interest as wavelength conversion materials for infrared applications. The maximum attainable ζ(2) is in the range of 3500–4000 pm/V for bound electrons. For energy gaps less than one eV, the increase in ζ(2) with decreasing energy gap slows considerably.
The new orthoborate BaZn2(BO3)2 has been synthesized and its structure determined by single-crystal X-ray methods. It crystallizes in an orthorhombic cell with dimensions a = 9.305(3), b = 12.128(1), and c = 4.9255(8) Å the space group is P212121. The structure was determined from 876 independent reflections and refined to the final residuals R = 0.024 and Rw = 0.034. It exhibits a three-dimensional framework of vertex-sharing ZnO4 tetrahedra and BO3 triangles that isolates Ba atoms in channels extending along the c axis. The optical second harmonic signal generated from a 1064-nm fundamental and microcrystalline sample is approximately 10% of that observed from the frequency converter potassium dihydrogen phosphate (KDP). This result is consistent with the magnitude of the nonlinearity computed on the basis of the anionic group model.
A study has been made of the factors which determine the transmission limits of the II–IV–V2 and I–III–VI2 ternary semiconductor compounds in view of their possible use in infra-red non-linear devices. The results of new measurements are presented for the following compounds: ZnSiP2, CdSiP2, CuAlS2, CuAlSe2, CuGaS2, CuGaSe2. AgGaS2, AgGaSe2, and AgInS2. Details are given of their fundamental absorption edges, two-phonon summation bands, and Reststrahl bands. Some conclusions are drawn regarding the mechanisms of band-edge absorption. A transmission limit is defined as the wavelength at which the absorption coefficient has increased to 3 cm−1. A full summary is included of all known data on the transmission ranges of the principal ternary compounds.Es wurden die Faktoren untersucht, die die Grenzen der Transmission der ternären II–IV–V2- und I–III–VI2-Halbleiterverbindungen im Hinblick auf ihre Verwendung für nichtlineare Infrarotbauelemente bestimmen. Ergebnisse neuer Messungen werden für folgende Verbindungen mitgeteilt: ZnSiP2, CdSiP2, CuAlS2, CuAlSe2. CuGaS2, CuGaSe2. AgGaS2, AgGaSe2 und AgInS2. Detaillierte Angaben werden über die Grundgitterabsorptionskanten, Zwei-Phononensummenbanden und die Reststrahlenbanden gemacht. Die Transmissionsgrenzen werden als die Wellenlänge definiert, bei der die Absorptionskoeffi-zienten auf 3 cm−1 angestiegen sind. Außerdem wird ein vollständiger Überblick aller bekannten Daten über die Transmissionsbereiche der hauptsächlichen ternären Verbindungen angegeben.
Optical parametric oscillation in beta-barium borate has been demonstrated using synchronous pumping by the frequency doubled output train from an actively mode-locked and Q-switched Nd: YAG laser. The parametric oscillator converts up to ~ 30% of the pump train to produce broadly tunable pulses (0.68 to 2.4 mum) of ~ 75 ps duration, with peak idler powers of up to ~ 1.6 MW. The tuning range has been extended up to 0.53 mum by frequency doubling the idler output with up to ~ 3% efficiency.
In the past 30 years, the frequency conversion of laser radiation in non-linear optical crystals has become an important technique widely used in quantum electronics and laser physics. The fundamental physics of this process is largely understood but the search for novel high-efficiency optical materials continues. This book provides a complete description of the properties and applications of all non-linear crystals reported in the literature up to the beginning of 1990. It also includes the most important equations for calculating parameters of non-linear frequency converters. This textbook on nonlinear optics and laser physics is intended for researchers, engineers and postgraduate students.
Hitherto we know boron in a trigonal-planar and a tetrahedral coordination within one crystal structure from boron oxides in various compounds. With the novel bariummetathioborate BaB2S4 we now report a crystal structure containing BS3 and BS4 units in the ratio 1:1 forming infinite chains along [001]. BaB2S4 was synthesized in a solid state reaction at a temperature of 800°C from barium sulfide, amorphous boron and sulfur and crystallizes in the monoclinic space group Cc (no. 9) with the following lattice parameters: a = 6.6465(5) Å, b = 15.699(1) Å, c = 6.0306(5) Å, β = 110.96(1)°, Z = 4.
The thioborates Sr-3(BS3)(2) and Sr-3(B3S6)(2) were prepared from strontium sulfide, amorphous boron and sulfur in solid state reactions at a temperature of 1123 K. In a systematic study on the structural cation influence on this type of ternary compounds, the crystal structures were determined by single crystal X-ray diffraction. Sr3(BS3)2 crystallizes in the monoclinic spacegroup C2/c (No. 15) with a = 10.187(4) Angstrom, b = 6.610(2) Angstrom, c = 15.411(7) Angstrom, beta = 102.24(3)degrees and Z = 4. The crystal structure of Sr-3(B3S6)(2) is trigonal, spacegroup R (3) over bar (Nr. 148), with a = 8.605(1) Angstrom, c = 21.542(4) Angstrom and Z = 3. Sr-3(BS3)(2) contains isolated [BS3](3-) anions with boron in a trigonal-planar coordination. The strontium cations are found between the layers of orthothioborate anions. Sr-3(B3S6)(2) consists of cyclic [B3S6](3-) anions and strontium cations, respectively.
A new anhydrous, noncentrosymmetric orthoborate has been prepared and its crystal structure determined by X-ray diffraction of a single crystal. The material crystallizes in the orthorhombic system with a = 15.068(2), b = 8.720(2), and ; the space group is Pca21 and Z = 8. The final residuals were R = 0.083 and Rw = 0.112 for 1140 reflections. The structure is composed of layers of ZnO4 tetrahedra and BO3 triangles connected through shared oxygen vertices; these layers are connected by additional interleaving BO3 triangles and barium atoms. Calculations of the efficacy of the structure for second harmonic generation are discussed.
We have synthesized and characterized a high-temperature, cubic polymorph of Pb2GeS4, whose existence had been noted by Moh [N. Jb. Miner. Abh. 128 (1976) 115] and Elli and Mugnoli [Rend. Sci. Fis. Mat. Nat. 33 (1962) 315], but whose structure has not yet been reported. Synthesized directly from the elements, α-Pb2GeS4 and members of the Pb2−xSnxGeS4−ySey solution (0≤x≤0.5, 0≤y≤4) form in the non-centrosymmetric space group I4̄3d, with Z=16 and lattice parameters ranging from a=14.103 Å for the red α-Pb2GeS4 phase, to a=14.573 Å for the dark-grey Pb2GeSe4 phase. These compounds contain isolated [Ge(S,Se)]4− tetrahedra and two different sites for the metal counter-cations. Confirming the non-centrosymmetric nature of their structures, α-Pb2GeS4 and Pb2GeSe4 show weak second harmonic generation responses when irradiated with 1064-nm laser light.
Na1.5Pb0.75PSe4 was synthesized by the reaction of Pb with a molten mixture of Na2Se/P2Se5/Se at 495°C. Na0.5Pb1.75GeS4 was synthesized by reacting Pb and Ge in molten Na2Sx at 530°C. Likewise, Li0.5Pb1.75GeS4 can be synthesized in a Li2Sx flux at 500°C. Na0.5Pb1.75GeS4 and Li0.5Pb1.75GeS4 are relatively air- and water-stable, while Na1.5Pb0.75PSe4 is only stable in air and water for less than 1 day. The structures of all three compounds were determined by single-crystal X-ray diffraction. The compounds crystallize in the cubic, noncentrosymmetric space group I43d with a=14.3479(2) Å, Z=16, R1=0.0226, and wR2=0.0517 for Na1.5Pb0.75PSe4, a=14.115(1) Å, Z=16, R1=0.0284, and wR2=0.0644 for Na0.5Pb1.75GeS4, and a=14.0163(6) Å, Z=16, R1=0.0273, and wR2=0.0637 for Li0.5Pb1.75GeS4. The compounds adopt a structure that is similar to that of Ba3CdSn2S8 and feature [PSe4]3− or [GeS4]4− tetrahedral building blocks. In this three-dimensional structure, there are two types of metal sites. In each structure, these sites are occupied differently because of a disorder between the alkali and lead cations. All three compounds are semiconductors with band gaps around 2 eV. The observation of a large second harmonic generation (SHG) signal for Na0.5Pb1.75GeS4 indicates that it may be a potential nonlinear optical (NLO) material. Infrared and Raman spectroscopic characterization is also reported.
Systematische Studien zur Synthese neuer Erdalkalimetallthioborate und zum Kationeneinfluß auf die Strukturen ternärer Verbindungen dieses Typs führten zu den Strontiumthioboraten Sr3(BS3)2 und Sr3(B3S6)2. Die neuen Verbindungen wurden aus Strontiumsulfid, amorphem Bor und Schwefel in Festkörperreaktionen bei einer Temperatur von 1123 K dargestellt. Die Kristallstrukturen wurden durch Röntgenstrukturanalysen an Einkristallen bestimmt. Sr3(BS3)2 kristallisiert in der monoklinen Raumgruppe C2/c (Nr. 15) mit a = 10, 187(4) Å, b = 6, 610(2) Å, c = 15, 411(7) Å, β = 102, 24(3)° und Z = 4. Die Kristallstruktur von Sr3(B3S6)2 ist trigonal, Raumgruppe R3¯ (Nr. 148), mit a = 8, 605(1) Å, c = 21, 542(4) Å und Z = 3. Sr3(BS3)2 enthält isolierte [BS3]3—-Anionen mit Bor in trigonal-planarer Koordination. Die Strontiumkationen befinden sich zwischen Schichten von Orthothioborat-Anionen. Im Sr3(B3S6)2 liegen neben Strontiumkationen [B3S6]3—-Anionen vor.
Sr3(BS3)2 and Sr3(B3S6)2: Two Novel Non-oxidic Chalcogenoborates with Boron in a Trigonal-Planar Coordination
The thioborates Sr3(BS3)2 and Sr3(B3S6)2 were prepared from strontium sulfide, amorphous boron and sulfur in solid state reactions at a temperature of 1123 K. In a systematic study on the structural cation influence on this type of ternary compounds, the crystal structures were determined by single crystal X-ray diffraction. Sr3(BS3)2 crystallizes in the monoclinic spacegroup C2/c (No. 15) with a = 10.187(4) Å, b = 6.610(2) Å, c = 15.411(7) Å, β = 102.24(3)° and Z = 4. The crystal structure of Sr3(B3S6)2 is trigonal, spacegroup R3¯ (Nr. 148), with a = 8.605(1) Å, c = 21.542(4) Å and Z = 3. Sr3(BS3)2 contains isolated [BS3]3— anions with boron in a trigonal-planar coordination. The strontium cations are found between the layers of orthothioborate anions. Sr3(B3S6)2 consists of cyclic [B3S6]3— anions and strontium cations, respectively.
Systematic studies on quaternary thio- and selenoborates containing heavier alkaline earth metal cations led to the two new isotypic crystalline phases Sr4.2Ba2.8(BS3)4S and Ba7(BSe3)4Se. Both compounds consist of trigonal-planar BQ3 (Q = S, Se) units, isolated Q2- anions and the corresponding counter-ions. The two new chalcogenoborates were prepared in solid state reactions from the metal sulfides (selenides), amorphous boron and sulfur (selenium). Evacuated carbon coated silica tubes were used as reaction vessels since temperatures up to 870 K were applied. Sr4.2Ba2.8(BS3)4S and Ba7(BSe3)4Se crystallize in the monoclinic space group C2/c (no. 15) with a = 9.902(3) Å, b = 23.504(9) Å, c = 9.884(3) Å, β = 90.01(3)° and Z = 4 in the case of the thioborate, while for the selenoborate the lattice parameters a = 10.513(2) Å, b = 25.021(5) Å, c = 10.513(2) Å, β = 90.10(3)° were determined. X-ray powder patterns are compared to calculated diffraction data obtained from single crystal X-ray structure determination.
Es wird über die beiden Orthothioborate Li3BS3 (Pnma; a = 8,144(1) Å, b = 10,063(2) Å, 6,161(1) Å; Z = 4) und LiSrBS3 (Pnma; a = 7,557(1) Å, b = 9,083(2) Å, c = 7,049(1) Å; Z = 4) berichtet. Die beiden neuen Phasen wurden durch Hochtemperatur-Schmelzreaktion aus den Metallsulfiden, amorphem Bor und Schwefel bei 700°C dargestellt. Beide Verbindungen enthalten isolierte, planare [BS3]3−-Anionen. Die Lithiumionen sind vierfach (Li3BS3) bzw. sechsfach (LiSrBS3) von Schwefel umgeben, das Strontiumion weist eine achtfache Schwefelkoordination auf. Li3BS3 und LiSrBS3 bilden neue A3BX3 bzw. AA′BX3-Strukturtypen.Li3BS3 and LiSrBS3: New Orthothioborates with Trigonal Planar Boron CoordinationWe report on the two new orthothioborates Li3BS3 (Pnma; a = 8.144(1) Å, b = 10.063(2) Å, 6.161(1) Å; Z = 4) and LiSrBS3 (Pnma; a = 7.557(1) Å, b = 9.083(2) Å, c = 7.049(1) Å: Z = 4). The two new phases were prepared by reaction of the metal sulfides, amorphous boron, and sulfur at 700°C. Both compounds contain isolated, planar [BS3]3−-anions. The lithium ions have fourfold (Li3BS3) and sixfold (LiSrBS3) sulfur coordination, the strontium ion shows an eightfold sulfur coordination. The two compounds represent new A3BX3 resp. AA′BX3 structure types.
For the first time perthioborates with trigonal planar coordination of boron were prepared. Na2B2S5 (Pnma, a = 12.545(2) Å, b = 7.441(1) Å, c = 8.271(1) Å, Z = 4) and Li2B2S5 (Cmcm, a = 15.864(1) Å, b = 6.433(1) Å, c = 6.862(1) Å, Z = 4) were obtained by reaction of the metal sulfides with stoichiometric amounts of boron and an excess of sulfur (effective molar ratio M:B:S = 1:1:4) at 600°C (650°C) and subsequent annealing. The non-isotypic structures contain exactly planar [B2S5]2− groups consisting of five-membered B2S3 rings with one additional exocyclic sulfur on each of the boron atoms. The alkaline metal cations are four-coordinate (lithium) and (four + four)-coordinate (sodium) respectively.Na2B2S5 und Li2B2S5: Zwei neue Perthioborate mit planaren 1,2,4-Trithia-3,5-Diborolan-RingenNa2B2S5 (Pnma, a = 12,545(2) Å, b = 7,441(1) Å, c = 8,271(1) Å, Z = 4) und Li2B2S5 (Cmcm, a = 15,864(1) Å, b = 6,433(1) Å, c = 6,862(1) Å, Z = 4) konnten durch Reaktion der Metallsulfide mit amorphem Bor und elementarem Schwefel im Atomverhältnis 1:1:4 bei einer Reaktionstemperatur von 600°C (650°C) dargestellt werden. Die Kristallstrukturen bestehen aus planaren, isolierten [B2S5]2−-Fünfringen, zwischen denen sich die (vier)- (Lithium) bzw. (vier + vier)-fach (Natrium) koordinierten Kationen befinden.
Li5B7S13 (C2/c; a = 17,304(2) Å, b = 21,922(3) Å, c = 12,233(2) Å, β = 134,91(1)°; Z = 8 und Li9B19S33 (C2/c; a = 23,669(9) Å, b = 14,361(3) Å, c = 12,237(3) Å, β = 103,77(2)°; Z = 4 wurden durch Reaktion von stöchiometrischen Mengen Lithiumsulfid, Bor und Schwefel bei 750°C (Li5B7S13) und 700°C (Li9B19S33) mit anschließendem Tempern dargestellt. Die Kristallstrukturen bestehen aus sich durchdringenden, polymeren Bor-Schwefel-Anionengerüsten, die durch Eckenverknüpfung von B4S10- und B10S20-Einheiten (Li5B7S13) bzw. B19S36-Einheiten (Li9B19S33) gebildet werden. Dazwischen befinden sich die Lithiumkationen, wobei bei Li9B19S33 eine starke Fehlordnung beobachtet wird.Li5B7S13 and Li9B19S33: Two Lithium Thioborates with Novel Highly Polymeric Anion NetworksLi5B7S13 (C2/c; a = 17.304(2) Å, b = 21.922(3) Å, c = 12.233(2) Å, β = 134.91(1)°; Z = 8) and Li9B19S33 (C2/c; a = 23.669(9) Å, b = 14.361(3) Å, c = 12.237(3) Å, β = 103.77(2)°; Z = 4) were prepared by reaction of stoichiometric amounts of lithium sulfide, boron, and sulfur at 750°C (Li5B7S13) and 700°C (Li9B19S33) with subsequent annealing. The crystal structures consist of interpenetrating, polymeric boron sulfur anion networks which are formed by corner-sharing of B4S10 and B10S20 units (Li5B7S13), or B19S36 units (Li9B19S33). The lithium cations are situated in between with a strong disorder in Li9B19S33.
Na2B2Se7 (I 2/a; a = 11,863(4) Å, b = 6,703(2) Å, c = 13,811(6) Å, β = 109,41(2)°; Z = 4); K2B2S7 (I 2/a; a = 11,660(2) Å, β = 6,827(1) Å, c = 12,992(3) Å, β = 106,78(3)°; Z = 4) und K2B2Se7 (I 2/a; a = 12,092(4) Å, b = 7,054(2) Å, c = 13,991(5) Å, β = 107,79(3)°; Z = 4) wurden durch Reaktion stöchiometrischer Mengen des Metallsulfids (-selenids) mit Bor und Schwefel (bzw. Bordiselenid) bei 600°C mit anschließendem Tempern dargestellt. Die Kristallstrukturen bestehen aus kettenförmigen ([B2S7]2−)n- bzw. ([B2Se7]2−)n-Polyanionen aus spirocyclisch verknüpften B2S3 (B2Se3)-Fünfringen und B2S4(B2Se4)-Sechsringen, zwischen denen sich die neunfach koordinierten Alkalimetallkationen befinden.Na2B2Se7, K2B2S7, and K2B2Se7: Three Perchalcogenoborates with a Novel Polymeric Anion NetworkNa2B2Se7 (I 2/a; a = 11.863(4) Å, b = 6.703(2) Å, c = 13.811(6) Å, β = 109.41(2)°; Z = 4), K2B2S7 (I 2/a; a = 11.660(2) Å, β = 6.827(1) Å, c = 12.992(3) Å, β = 106.78(3)°; Z = 4), and K2B2Se7 (I 2/a; a = 12.092(4) Å, b = 7.054(2) Å, c = 13.991(5) Å, β = 107.79(3)°; Z = 4) were prepared by reaction of stoichiometric amounts of sodium selenide (potassium sulfide) with boron and sulfur or of potassium selenide and boron diselenide, respectively, at 600°C with subsequent annealing. The crystal structures consist of polymeric anion chains of composition ([B2S7]2−)n or ([B2Se7]2−)n formed by spirocyclically connected five-membered B2S3 (B2Se3) rings and six-membered B2S4 (B2Se4) rings. The nine-coordinate alkaline metal cations are situated in between.
Li4−2xSr2+xB10S19 (x ≈ 0,27) und Na6B10S18 wurden aus der Summenformel entsprechenden Mengen Strontiumsulfid und Lithiumsulfid (Natriumsulfid), amorphem Bor und Schwefel bei 700°C in graphitierten Quarzglasampullen dargestellt. Li4−2xSr2+xB10S19 (x ≈ 0,27) kristallisiert monoklin in der Raumgruppe P21/c mit a = 10,919(2) Å, b = 13,590(3) Å, c = 16,423(4) Å, und β = 90,48(2)°, Na6B10S18 tetragonal in der Raumgruppe I41/acd mit a = 14,415(3) Å, c = 26,137(4) Å. Beide Strukturen enthalten supertetraedrische B10S20-Einheiten, die über Tetraederecken zu einem dreidimensionalen polymeren anionischen Raumnetzwerk im Falle des Na6B10S18 bzw. zu eindimensionalen Anionen-Ketten im Falle des Li4−2xSr2+xB10S19 (x ≈ 0,27) verbunden sind. Alle Boratome haben tetraedrische BS4-Koordination (die BS-Abstände variieren von 1,879(5) Å bis 1,951(5) Å (1,875(10) Å bis 1,987(9) Å)). Die Strontium- und Lithium-(Natrium-)Kationen befinden sich in ausgedehnten Kanälen innerhalb des Anionengerüsts.
Farblose, plättchenförmige Kristalle von RbBS3 (P21/c, a=7,082(2) Å, b=11,863(4) Å, c=5,794(2) Å, β=106,54(2)°) entstehen aus einem stöchiometrischen Ansatz von Rubidiumsulfid, Bor und Schwefel bei 600°C und anschließendem Tempern. Die zu RbBS3 isotype Phase TlBS3 (P21/c, a=6,874(3) Å, b=11,739(3) Å, c=5,775(2) Å, β=113,08(2)°) erhält man aus dem Ansatz Tl2S · 2 B2S3. Das nach 7 h bei 850°C erhaltene glasige Produkt wird in einem Zweizonenofen 400 h bei 400350°C ausgelagert. Gelbe Kristalle der Verbindung bilden sich in der wärmeren Ofenzone. Das ebenfalls gelbe Tl3B3S10 (P1, a=6,828(2) Å, b=7,713(2) Å, c=13,769(5) Å, α=104,32(2)°, β=94,03(3)β, γ=94,69(2)°) bildet sich aus stöchiometrischen Mengen von Thalliumsulfid, Bor und Schwefel bei 850°C und anschließendem Tempern.
LiBaBS3 (P21/c; a = 7,577(2) Å, b = 8,713(2) Å, c = 8,687(2) Å, β = 116,22(2)°; Z = 4) und LiBaB3S6 (Cc; a = 15,116(3) Å, b = 8,824(2) Å, c = 8,179(2) Å, β = 117,46(3)°; Z = 4) wurden durch Reaktion stöchiometrischer Mengen der Metallsulfide mit Bor und Schwefel bei 750°C dargestellt. Die Anionenteilstruktur des Orthothioborats LiBaBS3 besteht aus isolierten, planaren [BS3]3−-Anionen. Die Kristallstruktur des Metathioborats LiBaB3S6 enthält [B3S6]3−-Anionen aus B3S3-Sechsringen mit drei exocyclischen Schwefelatomen. Die Metallkationen befinden sich jeweils zwischen den Anioneneinheiten, wobei für Barium eine neunfache, für Lithium eine fünffache (LiBaBS3) bzw. vierfache (LiBaB3S6) Koordination durch Schwefel beobachtet wird. LiBaBS3 and LiBaB3S6: Two New Quaternary Thioborates with Trigonally Coordinated Boron LiBaBS3 (P21/c; a = 7.577(2) Å, b = 8.713(2) Å, c = 8.687(2) Å, β = 116.22(2)°; Z = 4) und LiBaB3S6 (Cc; a = 15.116(3) Å, b = 8.824(2) Å, c = 8.179(2) Å, β = 117.46(3)°; Z = 4) were prepared by reaction of stoichiometric amounts of the metal sulfides, boron, and sulfur at 750°C. The anionic part of the structure of the orthothioborate LiBaBS3 consists of isolated planar [BS3]3− anions. The crystal structure of the metathioborate LiBaB3S6 contains [B3S6]3− anions formed by six-membered B3S3 rings with three exocyclic sulfur atoms. The metal cations are situated between the anion units leading to a ninefold sulfur coordination of the barium atoms and to a fivefold (LiBaBS3) and fourfold (LiBaB3S6) coordination of the lithium atoms.
DOI:https://doi.org/10.1103/PhysRevLett.7.118
Study of the linear and non-linear properties of AgGaS2 is reported. This compound is an interesting material for non-linear optics infrared and is also important as a representative of a large family of potentially phase-matchable and highly non-linear materials.The non-linear susceptibility (d14 = 1.3 × 10-7 esu) was determined from a phase-matched SHG experiment with a CO2 laser.
Tl3BS3 (1) and Tl3BSe3 (2) were prepared as black crystalline phases by reaction of stoichiometric amounts of the elements at 800–950 °C and subsequent annealing at 400-200 °C. They are the first orthothio- and orthoselenoborates which have been characterized. According to single-crystal structure analyses, they contain trigonal planar BS33− (B-S bond length 1.83 Å) and BSe33− groups (B-Se bond length 1.95 Å). There are two structurally different thallium atoms in the structure with irregular 6 + 1- or 6 + 2-coordination by sulphur (selenium), the inert electron pair at Tl+ showing strong stereochemical activity. The crystal structures of 1 and 2 are isotypic to each other but not isotypic to any other M3AB3 structure. They are monoclinic, space group , with a = 5.444, b = 9.699, , β = 98.13δ for 1; and a = 5.547, b = 10.099, , β = 97.59° for 2, Z = 2. Vibrational spectra, mass spectra and thermoanalytic results for 1 and 2 are reported.
The dependence on wavelength of repetitive-pulse (10 Hz, 8 10 ns) laser-induced damage on beta barium metaborate (BBO) has been investigated. The thresholds of dielectric breakdown in bulk crystal have been found to be 0.3 GW cm 2 at 266 nm, 0.9 GW cm 2 at 355 nm, 2.3 GW cm 2 at 532 nm, and 4.5 GW cm 2 at 1064 nm. Results indicate two-photon absorption at 266 and 355 nm, which helps to produce an avalanche effect that causes breakdown at each of the four wavelengths tested. Neither the BBO refractive indices nor the absorption spectrum change until breakdown occurs.
The dichotomy method for indexing powder diffraction patterns for low-symmetry lattices is studied in terms of an optimization of bound relations used in the comparison of observed data with the calculated patterns generated at each level of the analysis. A rigorous mathematical treatment is presented for monoclinic and triclinic cases. A new program, DICVOL91, has been written, working from the cubic end of the symmetry sequence to triclinic lattices. The search of unit cells is exhaustive within input parameter limits, although a few restrictions for the hkl indices of the first two diffraction lines have been introduced in the study of triclinic symmetry. The efficiency of the method has been checked by means of a large number of accurate powder data, with a very high success rate. Calculation times appeared to be quite reasonable for the majority of examples, down to monoclinic symmetry, but were less predictable for triclinic cases. Applications to all symmetries, including cases with a dominant zone, are discussed.
Ag6B10S18 wurde als neues Thioborat aus Ag2S, Bor und Schwefel bei 700°C mit anschließendem Tempern bei 580–460°C dargestellt. Die orange‐gelbe Verbindung kristallisiert monoklin, Raumgruppe C2/c, mit a = 21,663(8), b = 21,639(8), c = 16,572(5) Å, ß = 129,40(4)°, Z = 8, drönt. = 2,948 g · cm⁻³. Wie die vollständige Röntgenstrukturanalyse zeigt, enthält Ag6B10S18 im anionischen Teil B10S20‐„Supertetraeder”, die aus zehn parallelen, über Ecken verknüpften BS4‐Tetraedern bestehen; die B10S20‐Gruppen sind über Ecken schichtartig zu (B10S16S4/2⁶⁻)ⁿ = (B10S18⁶⁻)n‐Polyanionen verbunden. Die mittlere BS‐Bindungslänge beträgt 1,915 Å. Die Elektronendichte im Bereich der Ag⁺‐Ionen zeigt eine dynamische fehlgeordnete Anordnung, die durch eine Verteilung der 6 Ag⁺‐Ionen der asymmetrischen Einheit auf 18 partiell besetzte Punktlagen beschrieben werden kann. Damit sind die strukturellen Voraussetzungen für Ag⁺‐Ionenleitung gegeben. Das IR‐Spektrum zeigt BS‐Valenzschwingungen bei 610, 640, 685, 735 und 760 cm⁻¹.
The boron–oxygen compound LiB3O5 is recognized as a new nonlinear-optical crystal. This follows theoretical calculations of the second-harmonic generation (SHG) coefficients using the anionic group theory and the complete neglect of differential overlap approximation to obtain the localized wave functions of component groups. An optically perfect single crystal with space group Pna21, grown at the Fujian Institute of Research on the Structure of Matter by the high-temperature flux method, is found to be transparent from 160 nm to 2.6 μm. It has a SHG coefficient comparable with that of β-BaB2O4 as well as two other outstanding advantages: a high damage threshold of 25 GW/cm2 (at 1.064 μm, 0.1 nsec) and a wide acceptance angle of 25 mrad for θ ≠ 90° and 95 mrad for θ = 90° with a 6-mm-long crystal.
The thioborates M3B3S6 (M = Na1,2, K1,2, Rb) and LiSrB3S6 were prepared from stoichiometric amounts of the metal sulfides, boron and sulfur. The crystal data for the isotypic M3B3S6, (M = Na, K, Rb) compounds are: space group R3c; a = 15.118(1), 15.520(5), 15.813(4) Å; c = 7.512(1), 8.424(3), 8.804(1) Å (hexagonal). The crystal data for the first quarternary thioborate LiSrB3S6 are: space group Cc; a = 14.933(6), b = 8.703(4), c = 7.866(3) Å, β = 116.76(3)°. All four metathioborates contain isolated B3S23- anions which form B3S3 rings with three exocyclic sulfur atoms.
The orthothioborates Na3BS3, K3BS3 and Rb3BS3 were prepared from the metal sulfides, amorphous boron and sulfur in solid state reactions at temperatures between 923 and 973 K. In a systematic study on the structural cation influence on this type of ternary compounds, the crystal structures were determined by single crystal X-ray diffraction experiments. Na3BS3 crystallizes in the monoclinic space group C2/c (No. 15) with a = 11.853(14) Å, b = 6.664(10) Å, c = 8.406(10) Å, β = 118.18(2)° and Z = 4. K3BS3 and Rb3BS3 are monoclinic, space group P21/c (No. 14) with a = 10.061(3) Å, b = 6.210(2) Å, c = 12.538(3) Å, β = 112.97(2) and a = 10.215(3) Å, b = 6.407(1) Å, c = 13.069(6) Å, β = 103.64(5)°, Z = 4. The potassium and rubidium compounds are not isotypic. All three compounds contain isolated [BS3]3- anions with boron in a trigonal-planar coordination. The sodium cations in Na3BS3 are located between layers of orthothioborate anions, in the case of K3BS3 and Rb3BS3 stacks of [BS3]3- entities are connected via the corresponding cations. X-ray powder patterns were measured and compared to calculated ones obtained from single crystal X-ray structure determinations.
Our systematic studies on quaternary thioborates containing both a comparably small alkali metal ion and a large alkaline earth cation lead to the two new crystalline phases KBa4(BS3)3 and K4Ba11(BS3)8S. The former consists of isolated BS3 units and the corresponding counter-ions while in the latter BS33- and S2- anions coexist. In both compounds boron is found in a trigonal-planar coordination, in the case of K4Ba11(BS3)8S the additional sulfide anions are located inside an octahedron built of six barium cations. The two compounds were prepared in solid state reactions from the metal sulfides, amorphous boron and sulfur. Evacuated carbon coated silica tubes were used as reaction vessels since temperatures up to 870 K were applied. KBa4(BS3)3 crystallizes in the monoclinic space group C 2/c (no. 15) with a = 14.299(6) Å, b = 8.808(3) Å, c = 13.656(5) Å, β = 98.72(4)°, and Z = 4, while for K4Ba11(BS3)8S the trigonal space group R3c (no. 167) was found with a = 18.146(3) Å, c = 25.980(7) Å, and Z = 6. X-ray powder patterns are compared to calculated diffraction data obtained from single crystal X-ray structure determination, in the case of K4Ba11(BS3)8S vibrational spectra were recorded.
Preparation schemes for high-purity vitreous B2S3 (v-B2S3) with a S:B ratio of 1.478 ± 0.032 are described. Preparation schemes reported in the literature are shown by very sensitive FT-IR measurements to yield v-B2S3 with significant oxygen contamination. Through extreme care taken in carbonizing silica reaction tubes and through the use of very high purity starting materials, oxygen contamination of less than 1% has been achieved. The IR spectrum for very pure v-B2S3 contains only two absorption bands.
The “subsolidus” phase relations at room temperature in the system CaO-B2O3-BaO are investigated. Specimens of various compositions were prepared from appropriate ratios of CaCO3, B2O3, and BaCO3, and fired from 780° to 1040°C according to their melting points. There are three ternary compounds in this system. The crystal structures of these compounds were determined by X-ray diffraction (XRD). CaBa2(BO3)2 and Ca5Ba2B10O22 are monoclinic structures. The lattice constants a= 14.221 Å, b= 4.569 Å, c= 11.926 A, β= 99.947°, and V= 763.4 å3 for CaBa2(BO3)2 and a= 15.714 å, b= 6.184 å, c= 10.204 å, β= 93.954°, and V= 989.29 å3 for Ca5Ba2B10O22 are obtained. The third compound, CaBa2(B3O6)2, is isostructural with the high form of BaB2O4 with lattice constants a= 7.167 å and c= 35.298 å. Powder second harmonic generation efficiencies of these ternary compounds were measured using a homemade apparatus.
What properties determine an effective nonlinear optical (NLO) material? These are reviewed and summarized for recently described borate compounds—materials that have proven to be superior to other commonly used NLO materials for UV applications. The Figure shows the arrangement of [B2O5] and [NbO6] groups within the unit cell of CsNbOB2O5.
The IR spectra of xCs2S+(1−x)B2S3 glasses and polycrystals are reported for the first time. Glasses can be continuously formed by quenching between two stainless steel plates out to x∼0.60. Single-phase polycrystals appear to form at x=0.33, 0.50, and 0.75. The IR spectrum of c-Cs2S:2B2S3 (x=0.33) shows that this phase consists of the dithioborate group having equal numbers of three- and four-co-ordinated borons similar to that of c-Rb2S:2B2S3. The Li, Na, and K dithioborate phases, however, consist solely of tetrahedral borons. The IR spectrum of c-Cs2S:B2S3, the meta-thioborate phase (x=0.50), shows that this phase consists of four-membered ring meta-thioborate groups, Cs2B2S4, with two non-bridging and two bridging sulfurs. Contrasting this behavior, the IR spectra of c-M2S:B2S3, with M=Na, K and Rb, shows that these phases are solely comprised of six-membered ring meta-thioborate groups, M3B3S6. For the polycrystal with x=0.75, c-Cs3BS3, the IR spectrum indicates that this phase consists of trigonal ortho-thioborate groups, Cs3BS3, similar to those of the Li, Na, K, and Rb phases. The IR spectra of glassy B2S3 has been shown by previous work to consist of equal fractions of isolated `loose' trigonal groups and six-membered thioboroxyl ring groups. With the addition of Cs2S to B2S3 in the low-alkali region (x<0.5) and similar to the behavior of the Na, K, and Rb thioborate glasses, the absorption band of the tetrahedral borons at ∼600–750 cm−1 reaches a maximum in intensity at x∼0.3. Tetrahedral borons appear to form initially from the loose trigonal groups, similar in behavior to the other alkali thioborate glasses. The IR glasses in the high-alkali region, x>0.5, resemble those of the other thioborate glasses where the fraction of the meta-thioborate groups decreases in preference to the formation of ortho-thioborate groups. Quite surprisingly, there is no IR spectral evidence of the formation of the four-membered ring Cs meta-thioborate groups in the glasses, even though this structure is observed in the polycrystals in this series.
A theoretical model suitable for calculating absorption edges of inorganic nonlinear optical (NLO) crystals is introduced. This model is proved to be useful to elucidate the relationship between electronic structures of NLO-active groups and macroscopic properties of absorption edges on the UV side of most of the inorganic nonlinear optical crystals. A systematic calculation of absorption edges on the UV side for several important inorganic NLO crystals is carried out by means of DV-SCM-X method and all calculated results are in good agreement with experimental data. These inorganic NLO crystals include LiB3O5(LBO), -BaB2O4(BBO), KB5, KDP, Na2SbF5, Ba2TiSi2O8, iodate and NaNO2. The calculated energy level structures of LiB3O5 and -BaB2O4 crystals are compared with the measured XPS spectra. The unusual transparent spectra of KB5 and KDP crystals are partly explained from the microstructure point of view. The effect of lone electron pair in iodate and NaNO2 crystals on their absorption edges are discussed. All these results show that Anionic Group Theory of Nonlinear Optical Crystals is useful to evaluate the absorption edges of the inorganic nonlinear optical crystal and is a powerful tool in a Molecular Engineering approach to search for new nonlinear optical materials.
Efficient second‐harmonic generation (SHG) at 5300 Å has been achieved with KDP and LiNbO 3 crystals when Nd‐glass lasers of high radiance and narrow bandwidth were used. With KDP and a diffraction‐limited laser system having a 19 Å bandwidth, 15 J of radiant energy at 5300 Å were obtained with a 51% energy‐conversion efficiency. Since the harmonic light pulse was narrower than the fundamental pulse, the peak‐power‐conversion efficiency was 70%. The peak power in the green was 1.0 GW. The ratio of harmonic‐fundamental pulse duration increased as SHG increased into the saturation region as expected. For LiNbO 3 , the relatively large dependence of phase‐matching angle on wavelength limits the maximum SHG efficiency to several percent when broad‐band lasers are used. With LiNbO 3 , therefore, a laser system was used having mode selectors which limited the bandwidth to less than 0.5 Å while the beam divergence was 1.5 mrad. In this case 21% energy conversion and 33% peak‐power conversion were obtained with a fundamental flux density of only 2 MW/cm<sup>2</sup> inside the crystal. The values found for the elements of the nonlinear dielectric tensor, corrected for the random multimode nature of the laser, are d 36 (KDP) = (1.1±0.1)×10<sup>-9</sup> esu and d 31 (LiNbO 3 ) = (17±6)×10<sup>-9</sup> esu. At low conversions a laser beam with fluctuations due to random multimoding is expected to give as much as twice the harmonic produced by a single‐mode laser. At high conversions in the saturation region this ``doubling'' does not occur as verified by our measurements.
The second harmonic of a Nd laser has been produced in LiIO 3 in a phase matching direction of 30° to the c axis with high conversion efficiency. The nonlinear optical coefficient t 31 is among the highest so far reported for phase matchable substances using λ = 1.06 μ. LiIO 3 can be grown from water solutions with excellent optical quality.
Proustite (Ag<sub>3</sub>AsS<sub>3</sub>), a new acentric crystal for optical mixing, has been synthesized as large transparent single crystals. It is uniaxial, having point group symmetry 3m. Proustite transmits from 0.6 to 13 μm, and has a large negative birefringence (n<sub>0</sub> - n<sub>E</sub> ∼ 0.2). Using second-harmonic generation from a 1.152-μm laser, we estimate the nonlinear coefficients to be |d<sub>22</sub><sup> P </sup>|=50|d<sub>36</sub><sup> KDP </sup>| and |d<sub>31</sub><sup> P </sup>|=30|d<sub>36</sub><sup> KDP </sup>| . New optical mixing possibilities arise from the exceptionally wide range of processes that can be phase-matched and the large nonlinear coefficients.
Li6+2x[B10S18]Sx (x≈2), a novel thioborate-sulfide double salt, was prepared from the elements by reaction at 750° C in a graphitized sealed tube, and single crystals were obtained by annealing at 550-500°C. The crystal structure (space group C2/c, a=20.996(5), b=21.157(4), , β= 128.53(1) °) contains a well-defined polymeric thioborate network of composition position [B10S186−]n consisting of a system of edge-sharing adamantanoid macro-tetrahedra. Two rigid symmetry-related interpenetrating networks of this kind form large channels in which a strongly disordered system of lithium and sulfide ions (10Li+ and 2 S2− per formula unit) is observed. The dynamic behaviour of the lithium ions in the crystalline compound was investigated from the temperature and frequency dependence of the 7Li NMR spectra.
The dependence on wavelength of repetitive-pulse (10 Hz, 8-10 ns) laser-induced damage on beta barium metaborate (BBO) has been investigated. The thresholds of dielectric breakdown in bulk crystal have been found to be 0.3 GW/cm(2) at 266 nm, 0.9 GW/cm(2) at 355 nm, 2.3 GW/cm(2) at 532 nm, and 4.5 GW/cm(2) at 1064 nm. Results indicate two-photon absorption at 266 and 355 nm, which helps to produce an avalanche effect that causes breakdown at each of the four wavelengths tested. Neither the BBO refractive indices nor the absorption spectrum change until breakdown occurs.
Efficient generation of high-power difference-frequency radiation, continuously tunable over the range of 4.4-5.7 mu m, has been achieved by mixing the Nd :YAG laser and Nd :YAG pumped infrared dye-laser outputs in LiIO 3 . Peak pulse powers as high as 550 kW with an average power output of 45 mW were obtained around 4.9μm.
This paper presents a detailed study of the optimum design parameters for the LiNbO 3 parametric oscillator. Theoretical and experimental studies of the optical parametric oscillator (OPO) threshold parameters and of linewidth control are presented. Consideration is given to practical factors that limit OPO performance such as laser beam quality and crystal damage mechanisms. In addition, stable single axial mode operation is reported.
The author reports the stable generation of 0.2-W average power IR
pulses around 3.2 μm from the KTP parametric oscillator pumped by the
Nd:YAG laser at 1.064 μm. In addition, improved Sellmeier's
equations, which correctly predict almost all of the nonlinear
experiments thus far reported, are presented, together with the absolute
values of d <sub>31</sub> and d <sub>32</sub>
- Miller R. C.
- Hammershmidt A.