Enrico Cavalli

• University Degree in Chemistry
• Professor (Associate) at University of Parma

In this contribution, we present new NIR-CPL/CD active Yb(III) complexes, which are synthesized by combining two ligands characterized by different types of chirality: central and axial chirality. The ligand bearing central chirality is represented by the neutral trans-N,N′-bis(2-pyridylmethylidene)-1,2-(R,R or S,S) cyclohexanediamine (L), whereas...

LuAG:Dy ³⁺ co-doped Tb ³⁺ transparent ceramics were fabricated and characterized to assess their potentialities as yellow emitting laser materials. The research focused on identifying and characterizing energy-transfer mechanisms from Dy ³⁺ to Tb ³⁺ ions, and vice versa .

The complexes [Eu(bpcd)(tta)], [Eu(bpcd)(Coum)], and [Tb(bpcd)(Coum)] [tta = 2-thenoyltrifluoroacetyl-acetonate, Coum = 3-acetyl-4-hydroxy-coumarin, and bpcd = N,N'-bis(2-pyridylmethyl)-trans-1,2-diaminocyclohexane-N,N'-diacetate] have been synthesized and characterized from photophysical and thermodynamic points of view. The optical and chiroptica...

In this contribution, we present the spectroscopic study of two NIR emitting hydrophobic heteroleptic (R,R)-YbL1(tta) and (R,R)-NdL1(tta) complexes (with tta = 2-thenoyltrifluoroacetonate and L1 = N,N′-bis(2-(8-hydroxyquinolinate)methylidene)-1,2-(R,R or S,S)-cyclohexanediamine), both in methanol solution and embedded in water dispersible and bioco...

Efficient near-infrared circularly polarised luminescence (CPL) between 1400 and 1600 nm of four enantiomer pairs of homo- and heteroleptic complexes have been successfully measured. Utilising inexpensive optics and a commercial...

Multiferroics, showing the coexistence of two or more ferroic orderings at room temperature, could harness a revolution in multifunctional devices. However, most of the multiferroic compounds known to date are not magnetically and electrically ordered at ambient conditions, so the discovery of new materials is pivotal to allow the development of th...

The structure of the potentially scintillating high-pressure phase of β−MgMoO4 (γ−MgMoO4) has been solved by means of high-pressure single-crystal x-ray diffraction. The phase transition occurs above 1.5 GPa and involves an increase of the Mo coordination from fourfold to sixfold accommodated by a rotation of the polyhedra and a concommitant bond s...

Novel chiral Er complexes based on both enantiomers of extended ⁱPrPyBox (2,6‐Bis[4‐isopropyl‐4,5‐dihydrooxazol‐2‐yl)]pyridine) show strong near‐infrared circularly polarized luminescence (CPL) within the 1400 to 1600 nm spectral region under 450 nm irradiation. CPL activity in this region, despite being particularly rare, would open the way to pot...

In this contribution, we present the synthesis, characterization and spectroscopic investigation of the heteroleptic (R,R)-YbL1(tta) and (R,R)-NdL1(tta) complexes (with tta = 2-thenoyltrifluoroacetonate and L1 = N,N′-bis(2-(8-hydroxyquinolinate)methylidene)-1,2-(R,R or S,S)-cyclohexanediamine) in the solid state. The f-f metal-centered NIR luminesc...

Novel chiral Er complexes based on both enantiomers of extended iPrPyBox (2,6‐Bis[4‐isopropyl‐4,5‐dihydrooxazol‐2‐yl)]pyridine) show strong near‐infrared circularly polarized luminescence (CPL) within the 1400 to 1600 nm spectral region under 450 nm irradiation. CPL activity in this region, despite being particularly rare, would open the way to pot...

We report the first example of very efficient NIR Circularly Polarized Luminescence (CPL) (around 970 nm) in water, obtained thanks to the combined use of a chiral Yb complex and of poly lactic‐co‐glycolic acid (PLGA) nanoparticles. [YbL(tta)2]CH3COO (L=N, N’‐bis(2‐pyridylmethylidene)‐1,2‐(R,R+S,S) cyclohexanediamine and tta=2‐thenoyltrifluoroaceto...

Flux grown crystals of YPO4, GdPO4, LaPO4, CaWO4, CaMoO4, KLa(MoO4)2, GdAl3(BO3)4, and GdTa7O19 activated with Tb3+ have been comparatively characterized by Raman and luminescence spectroscopy in order to investigate the relation between structural and emission properties. Processes like host sensitization, Tb3+- Tb3+ energy transfer, formation of...

A series of Er³⁺‐doped GdPO4 phosphors was synthesized using a conventional solid‐state reaction. The monazite structure (space group P121/n1) of the obtained materials was confirmed using X‐ray diffraction and Fourier transform infrared spectroscopy. Their optical spectra (excitation, emission, absorption, decay curves) were measured at room tempe...

This paper reports the author's point of view on the state of the art concerning the optical spectroscopy of Dy3+-containing materials, based on his personal experience and without claims of completeness, but with the intent to provide useful indications or at least elements for fruitful discussions to the people working on this subject. An overvie...

The luminescence properties of RAl3(BO3)4 (RAB, with R = Pr, Eu, Tb, Dy, Tm, Yb) huntite crystals grown from K2Mo3O10 flux were systematically characterized in order to investigate their excitation dynamics, with particular reference to the concentration quenching that in these systems is incomplete. To this purpose, selected excitation, emission,...

Eu³⁺ doped TiO2 powders were synthesized by solid-state reaction and hydrothermal-assisted sol-gel process. They were characterized by X-ray diffraction, scanning electron microscopy and photoluminescence techniques. Both synthetic procedures yield the pure anatase phase of titania. The excitation and emission spectra and the decay profiles were me...

Tb3+, Eu3+, Tm3+ tri-doped YPO4 powders were synthesized by high-temperature solid-state reaction in order to realize a white-light-emitting single-phase phosphor. Their photoluminescence spectra and time decay curves were measured. Nearly white luminescence was observed under 362 nm excitation for the sample doped with 2% Eu3+, 5% Tb3+ and 2% Tm3+...

The polarized absorption and emission spectra of a KPb2Cl5 (KPC) crystal activated with Ho³⁺ ions have been measured in the 400–4000 nm region. The absorption spectra have been analyzed in the framework of the Judd-Ofelt Theory and the results have been compared with those, contradictory, reported in literature. The emission measurements in near an...

Pr:CaGdAlO4 (Pr:CGA) crystals have been grown and investigated for the first time. A Na+ flux was designed to improve the crystal quality in the Czochralski method growth. The effect of the addition of the Na+ flux on the crystal quality has been investigated, and its beneficial impact on the crystallinity, on the optical homogeneity and on the the...

Green emitting YPO4:Tb3+ and orange-red emitting YPO4:Tb3+, Eu3+ phosphors were prepared by conventional solid-state reaction and characterized in order to develop materials for applications in white light-emitting diodes (w-LED). First, the doping level of singly doped YPO4:Tb3+ was systematically increased in order to obtain the highest green-to-...

We report a high-pressure study of tetragonal scheelite-type CaMoO4 up to 29 GPa. In order to characterize its high-pressure behavior, we have combined Raman and optical-absorption measurements with density-functional theory calculations. We have found evidence of a pressure-induced phase transition near 15 GPa. Experiments and calculations agree i...

We report a high-pressure study of tetragonal scheelite-type CaMoO4 up to 29 GPa. In order to characterize its high-pressure behavior, we have combined Raman and optical-absorption measurements with density functional theory calculations. We have found evidence of a pressure-induced phase transition near 15 GPa. Experiments and calculations agree i...

A rare-earth quantum memory The development of global quantum networks will require chip-scale optically addressable quantum memories for quantum state storage, manipulation, and state swapping. Zhong et al. fabricated a nanostructured photonic crystal cavity in a rare-earth-doped material to form a high-fidelity quantum memory (see the Perspective...

Single crystals of YVO4 and YPO4 doped with Sm³⁺ have been grown by the flux growth method. Their polarized absorption spectra, the luminescence spectra and the emission decay profiles have been measured at room temperature. The absorption spectra have been analyzed in the frame of the Judd-Ofelt Theory, and the evaluated radiative branching ratios...

The room temperature absorption spectra of Dy3+-doped GdVO4 and Ca3Sc2Ge3O12 crystals have been measured and analysed in the framework of the Judd-Ofelt Theory. The calculated intensity parameters have then been correlated with the intensities of the emission bands in the yellow and blue region. The analysis has then been extended to a number of ho...

The luminescence properties of Tb(3+) in CaWO4 crystals are investigated under a hydrostatic pressure of up to 200 kbar, i.e. across scheelite-to-fergusonite phase transition. It is shown that the typical blue ((5)D3) and green ((5)D4) emissions in this material are progressively quenched at room temperature as pressure is increased. This quenching...

The relations between the crystal lattice parameters and the properties of the constituting ions in a group of 109 compounds with the general formula MXO4 (M stands for a divalent, trivalent or tetravalent metal, and X=V, P, As, Si) having the zircon-type structure are considered in the present paper. It was shown that both a and c lattice paramete...

Laser slope and threshold properties have been investigated in Nd stoichiometric crystal powders as a function of pump wavelength and pump beam size. Above a given pumped area, the laser slope and the threshold pump energy per unit area are invariant and the known theoretical expressions are well fulfilled. Likewise, the size of the stimulated emis...

Y3Al5O12 (YAG) transparent ceramics doped with Pr3+ have been obtained by vacuum sintering of spray dried commercial powders and characterized by XRD and SEM techniques. A comprehensive spectroscopic investigation has then been carried out including: absorption spectra and decay time measurements in the visible-IR spectral region and x-ray and VUV...

A systematic investigation of the luminescence spectroscopy of Y(P,V)O4:Bi3+ is presented. The emission spectra and the decay curves are measured as a function of the host morphology, composition, temperature, excitation wavelength, and doping concentration. On this basis, the nature of the excited states and the radiative and non-radiative relaxat...

The luminescence properties of the yellow pigment BiMg2VO6 are revisited and those of BiMg2PO6, BiMg2VO6:Pr3+ and BiMg2VO6:Eu3+ are described. It is shown that the undoped systems exhibit broad band emission in the green or orange spectral regions, but only upon UV or near UV excitation. In contradiction with a previous report, we found that the bl...

Yttrium aluminum garnet (YAG)-based ceramics represent a valuable alternative to single crystals as active media in laser devices for specific applications. In this connection, the 1.5–1.65 µm emission channel of Er3+-doped YAG is of particular importance for the realization of diode pumped solid state lasers operating in the so-called ‘eye-safe’ r...

Photoluminescence spectra of CaWO4 doped with Pr3+ and Tb3 obtained at high hydrostatic pressures up to 315 kbar applied in a diamond anvil cell (DAC) are presented. The intensities of the luminescence from the 3P0 state of PO+ and from the D-5(3) state of Pr3+ decreased with increasing pressure. At pressures greater than 50 kbar, the D-1(2) <-> H-...

Transparent YAG ceramics doped with different concentrations of Tm3+ have been fabricated by solid state reactive sintering and their spectroscopic properties have been thoroughly investigated. Absorption, emission and fluorescence decay measurements have been carried out in different experimental conditions in order to obtain information about the...

YAG transparent ceramics singly doped with Er3+ and codoped with Yb3+ and Er3+ have been produced by vacuum sintering of the commercial powders. Prior to sintering powders have been spray dried, linear and cold isostatic pressed and finally calcinated at 600 °C. Their structural and morphological properties have been characterized by X-ray diffract...

The luminescence properties of YPO4 phosphors activated with 2% Sm3+ and variable concentrations of Bi3+ (from 0 to 5%) have been investigated. Steady state emission and decay time measurements clearly evidence an increment of the emission performance as the Bi3+ content increases up to 2.5%. Quantum yield measurements provide quantitative confirma...

Photoluminescence spectra and luminescence kinetics of pure CaMoO(4) and CaMoO(4) doped with Ln(3+) (Ln = Pr or Tb) are presented. The spectra were obtained at high hydrostatic pressure up to 240 kbar applied in a diamond anvil cell. At ambient pressure undoped and doped samples exhibit a broad band emission extending between 380 and 700 nm with a...

a b s t r a c t The luminescence properties of CaMoO 4 :Pr 3 þ have been investigated in different experimental conditions in order to obtain information on the excitation and de-excitation pathways of this system. The structure of the emission spectrum depends on different factors: excitation conditions, doping level, temperature, etc. In addition...

Steady state and time resolved emission measurements of CaWO4 doped with Pr3+ have been carried out as a function of hydrostatic pressure in the 1-315 kbar range. The increase of pressure induces several effects: a progressive red shift of the spectral features and a decrement of the decay times of both 3P0 and 1D2 emitting levels, the decrease of...

Single crystals of YPO4:Tb3+(1%) have been grown from Pb2P2O7 flux and their emission dynamics have been characterized by steady state and time resolved optical spectroscopy. The investigation has then been extended to green emitting phosphors with composition Y0.95−xTb0.05BixPO4 (x=0, 0.0025, 0.005, 0.01, 0.025), synthesized by the Pechini sol–gel...

The luminescence properties of CaTiO3 both singly and doubly doped with Bi3+ and Pr3+ have been measured in different experimental conditions in order to investigate the de-excitation processes active in these materials and in particular to understand the mechanism responsible for the significant increment of the red emission observed in the codope...

The luminescence properties of CaTiO(3) both singly and doubly doped with Bi(3+) and Pr(3+) have been measured in different experimental conditions in order to investigate the de-excitation processes active in these materials and in particular to understand the mechanism responsible for the significant increment of the red emission observed in the...

Steady state and time resolved luminescence measurements of CaMoO(4) doped with Pr(3+) as a function of hydrostatic pressure in the 1-175 kbar range are presented. It has been observed that with increasing pressure the spectral features shift towards lower energies, the decay times of both (3)P(0) and (1)D(2) emitting levels become shorter and the...

The luminescence properties of K(1/2)Bi(1/2)TiO(3):Pr(3+) and Na(1/2)Bi(1/2)TiO(3):Pr(3+) powders are investigated in the temperature range 10-600 K. The experimental data are interpreted on the basis of metal-to-metal charge transfer processes and by considering Bi(3+)-to-Pr(3+) sensitization effects.

The electronic structure of the Tm3+ in YAl3(BO3)4 crystals has been investigated by means of low temperature absorption and emission spectroscopy in the 5000–30,000 cm−1 range. The assignment of the lines composing the observed manifolds to transitions between the Stark levels of Tm3+ is complicated by the presence of extra features having differe...

The structural characteristics and optical spectra of Y(P,V)O4:Dy3+phosphors obtained by solid state reaction, sol–gel and hydrothermal routes have been investigated and compared. The luminescence features of these materials show a complicate dependence on the composition, synthetic method and excitation conditions. The emission performance depends...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Single crystals of Ba2NaNb5O15 doped with Pr3+ have been grown from sodium tetraborate flux. Their emission properties have been measured as a function of the doping level under different excitation and temperature conditions. The experimental observations have been accounted for by considering the effects of the crystal structure, of the doping me...

We demonstrate that Zeeman ground-state spin levels in Nd3+:YVO4Nd3+:YVO4 provides the possibility to create an efficient ΛΛ- system for optical pumping experiments. The branching ratio R in the ΛΛ-system is measured experimentally via absorption spectroscopy and is compared to a theoretical model. We show that R can be tuned by changing the orient...

Single crystals of CaWO(4) and CaMoO(4) doped with Tb(3+) have been grown by the flux growth method. Their luminescence properties have been investigated in the 10-600 K temperature range under different experimental conditions. In spite of very similar spectra at low temperature upon excitation at 365 nm, the crystals show a very different behavio...

In this work, Er(3+) and Tm(3+)-doped LiLa(9)(SiO(4))(6)O(2) crystals have been grown from an Li(2)MoO(4) flux in the 1360-940 °C temperature range. Optical absorption spectra have been measured to obtain the experimental oscillator strengths of the transitions from the ground state to the excited levels. Judd-Ofelt calculations have been performed...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

a b s t r a c t We will provide a method to place the levels of all trivalent lanthanides with respect to the top of the valence band and bottom of the conduction band in oxides containing transition metal complexes. The method will be applied to CaTiO 3 , YVO 4 , LaVO 4 , CaNb 2 O 6 , YNbO 4 , CaWO 4 , YTaO 4 , and LaTaO 4 , but in prin-ciple can...

Evidence of a positive optical gain has been observed in an Er3+-doped LuVO4 crystal in a pump and probe experiment. The radiative transition from the S-4(3/2) (H-2(11/2)) level to the I-4(13/2) metastable level of the Er3+ ion gives rise to an intense emission centred at 850 nm. The S-4(3/2)(H-2(11/2)) level of Er3+ ions is populated with high pow...

Transparent single crystals of erbium-doped LaVO4 in form of platelets having an average size 0.5×2×2mm3 were obtained by the flux method using Pb2V2O7 as the solvent. Inductively coupled plasma (ICP) measurement revealed that the actual Er/La=0.3% molar ratio in the crystals is lower than Er/La=1% nominal molar ratio due to significant difference...

Visible optical properties of two crystalline fibers (KY3F10 and LiLuF4) doped with Dy3+ have been investigated. In particular, the room-temperature absorption spectra have been analyzed using the Judd–Ofelt theory and the intensity parameters have been obtained. A criterion suitable for determining the proper choice of the dopant composition to ta...

a b s t r a c t Single crystals of Ba 2 NaNb 5 O 15 (BNN) singly doped with Sm 3 + , Eu 3 + , Tb 3 + or Dy 3 + have been grown by means of the flux growth method. Their visible emission and excitation spectra and the decay profiles of the luminescence have been measured at room temperature. All spectral features are significantly inhomogeneously br...

Positive optical gain around 5 cm ^-1 (∼21 dB / cm ) has been observed in Er ³⁺ -doped Ba ₂ NaNb ₅ O ₁₅ single crystal using a pump and probe experimental setup. High power laser pulses at 532 nm have been used as the pump source in order to strongly populate the ⁴ S _3/2(<s...

A comparative study concerning the electronic structure of the Mn5+ ion in the Li3PO4, Ca2PO4Cl, Sr5(PO4)3Cl host lattices has been carried out in the framework of the exchange charge model. The crystal field parameters have been evaluated using the structural data as the only input information. The 10 K absorption spectra of the investigated compo...

The excited state dynamics Y 1−xDyxPO4 (x=0.005−0.1) single crystals have been investigated as a function of the temperature and of the concentration. When x=0.005 the 4F9/2 emission decays exponentially with time constant of the order of 480–500 μs. For higher doping levels the curves are non exponential, indicating that energy transfer processes...

Photoluminescence and time resolved photoluminescence spectra of Y V O4 doped with Pr3+ obtained at high hydrostatic pressure up to 76 kbar applied in a diamond anvil cell are presented. At pressures lower than 60 kbar the steady state emission spectra consist of sharp lines peaking between 600 and 625 nm, related to 1D23→H4 transition in Pr3+ and...

Single crystals of Dy3+-doped YPO4 have been grown from Pb2P2O7 flux and investigated by optical spectroscopy techniques. The energy level scheme of the active ion has been deduced from the low temperature spectra and reproduced by means of a crystal-field calculation. The room temperature absorption spectra have been analysed in the framework of t...

LiLa9(SiO4)6O2 (LLS) crystals activated with Nd3+ have been grown from a lithium molybdate flux. Their absorption and emission spectra and fluorescence decay profiles have been measured at different temperatures. The spectra are affected by a significant inhomogeneous broadening as a consequence of the partial disorder of the crystal structure. The...

YTa{sub 7}O{sub 19} (YHT), Nd:YTa{sub 7}O{sub 19} (Nd:YHT), Nd:LaTa{sub 7}O{sub 19} (Nd:LHT) and NdTa{sub 7}O{sub 19} (NHT) single crystals have been grown by spontaneous nucleation from high-temperature solutions using K{sub 2}Mo{sub 3}O{sub 10}-B{sub 2}O{sub 3} as a flux and structurally characterized by X-ray diffraction techniques. The effect o...

The spectral properties of LaVO4, GdVO4 and LuVO4 crystals doped with Ce3+, Pr3+, Eu3+ or Tb3+ have been investigated in order to determine the position of the energy levels relative to the valence and conduction bands of the hosts along the trivalent and divalent lanthanide series. Pr3+ and Tb3+ ground state levels are positioned based on the elec...

Photoluminescence and time-resolved photoluminescence spectra of YVO4 doped with Pr3+ obtained at high hydrostatic pressure up to 76 kbar applied in a diamond anvil cell are presented. At pressures lower than 60 kbar the steady state emission spectra consist of sharp lines related to the transition in Pr3+. At pressures above 68 kbar the Pr3+ emiss...

The red phosphor CaTiO3 : Pr3+ is known to show a persistent luminescence in the red spectral region upon irradiation in the UV. Although a number of studies have been dedicated to the enhancement of the afterglow efficiency in this perovskite by varying the preparation method, the chemical composition or the particle size, no clear explanation of...

A comparative study concerning the electronic structure of the Mn 5+ ion in the Li 3 PO 4 , Ca 2 PO 4 Cl, Sr 5 (PO 4) 3 Cl host lattices has been carried out in the framework of the exchange charge model. The crystal field parameters have been evaluated using the structural data as the only input information. The 10 K absorption spectra of the inve...

LiLa9(SiO4)6O2 (LLS) crystals activated with Er3+ have been grown by the flux growth method. Their apatite structure has been characterized by single-crystal X-ray diffraction. The absorption and emission spectra have been measured in the visible and NIR regions. They are affected by a significant inhomogeneous broadening making these crystals inte...

The luminescence properties of KLa(MoO 4) 2 (KLM) single crystals doped with Pr 3+ have been measured in the 10–600 K temperature range in order to investigate the mechanisms involved in the radiationless processes. At variance with previously studied scheelite-like molybdates activated with Pr 3+ , no effects attributed to the formation of interva...

Single crystals of K2NdNb5O15 (KNdN) and Nd3+-doped K2LaNb5O15 (Nd:KLN) were grown by means of the flux growth technique. X-ray diffraction studies indicate that they belong to the tetragonal tungsten–bronze niobates family. The 10 and 298 K absorption and emission spectra and the luminescence decay curves were measured and discussed in the light o...

The luminescence properties of Tb 3+ doped into KLa(MoO 4) 2 crystals are presented. The intensity dependence of the emission fea-tures from 5 D 3 and 5 D 4 levels was investigated in the temperature range 10–600 K. The decay profiles of 5 D 3 emission have been analyzed using Inokuti–Hirayama model for an energy transfer process in the absence of...

We present spectral hole-burning measurements on the 879 nm, 4I9∕2→4F3∕2 transition in Nd3+:YVO4. We observe antiholes in the spectrum along with long lived spectral holes, which demonstrates optical pumping between the ground state Zeeman levels. The spectral holes are narrow (homogeneous linewidth of 63 kHz) at 2.1 K with a 300 mT applied magneti...

Single crystals of K2NdNb5O15 (KNdN) and Nd3+-doped K2LaNb5O15 (Nd:KLN) were grown by means of the flux growth technique. X-ray diffraction studies indicate that they belong to the tetragonal tungsten–bronze niobates family. The 10 and 298K absorption and emission spectra and the luminescence decay curves were measured and discussed in the light of...

Single crystals of MWO4 (M=Mg, Zn, Cd) and MgMoO4 doped with Cr3+ have been grown by the flux growth method. Their optical spectra have been systematically measured and assigned on the basis of the classical Ligand Field Theory. The exchange charge model of the crystal field has then been applied to calculate the crystal field parameters (CFPs) and...

Based on temperature dependent photoconductivity, excitation, and emission measurements we have established the absolute location of 4f energy levels of Pr 3+ , Eu 2+ and Tb 3+ doped in LaVO 4 . In combination with an empirical model describing a systematic and material independent variation of the 4f ground states of tri-and divalent lanthanides t...

Single crystals of Ba2NaNb5O15 (BNN) activated with Ho3+ and Tm3+ have been grown by the 'flux growth' technique. The absorption spectra, the visible emission properties and the decay curves of the excited states have been measured at 10 and 298 K. The room temperature absorption spectra have been analysed by means of the Judd–Ofelt theory and the...

The excitation and emission properties of Pr3+ and Tb3+ ions doped into YNbO4 (hereafter YNB) and CaNb2O6 (hereafter CNB) have been studied as a function of the temperature in the 10–600 K range. The observed quenching of the luminescence from the 3P0 (Pr3+) and 5D3 (Tb3+) states has been related to an electron transfer process from the trivalent r...

The absorption and emission spectra of Tm3+- and Ho3+-doped Ba2NaNb5O15 crystals have been measured in the 1.5–2 μm region. The lifetimes of the lowest excited states have been measured at 10 and at 298 K. The cross sections of the (Tm) 3F4 ↔ 3H6 and (Ho) 5I7 ↔ 5I8 transitions have been estimated and used to determine the (Tm) 3F4 → (Ho) 5I7 energy...

Reaction of phenylisothiocyanate with different aromatic amines allowed the synthesis of compounds containing the thiourea moiety. By reacting silver bis(triphenylphosphine)nitrate with suitable ligands belonging to this family of sulphurated compounds, three new complexes have been afforded. Ligands and complexes were characterized also by X-ray d...

The luminescence of Nd(3+) ions in Nd(x)Y(1-x)Al(3)(BO(3))(4) (Nd:YAB) single crystals has been investigated as a function of the neodymium concentration in order to evidence the relation between the structural and spectroscopic properties in this nonlinear laser system. The analysis of the experimental data allowed us to individuate four different...

RE:YAl 3(BO 3) 4 (RE = Yb, Er) and RETa 7O 19 (RE = Y, Nd, La) single crystals have been obtained using K 2Mo 3O 10 based flux by spontaneous nucleation as well as dipping seeded high-temperature solution growth. Their composition and physical characteristics were compared in light of the growth conditions. It was found that the average RE segregat...

The excited state dynamics of the Pr 3+ in oxide lattices is revisited in the light of the 'virtual recharge' model. The connection between the quenching of the blue-green emission from the 3 P 0 level and the formation of a Pr 3+ to metal intervalence charge-transfer state (IVCTS) is discussed on the basis of new experimental evidences. Updated in...

The quenching of the luminescence originating from the excited states 3P0 and 1D2 of Pr3+ and 5D3 and 5D4 of Tb3+ has been studied in oxide crystals containing closed shell transition metal ions, such as titanates, vanadates, niobates, and tantalates. It has been shown that the emission from these excited states can be quenched by an intervalence c...

Flux grown YAl3(BO3)4 (YAB) crystals doped with Tm3+ have been characterised by optical spectroscopy techniques. The absorption and emission spectra in the UV-VIS-NIR region have been measured at 10 and 298 K. The visible emission decay profiles have been measured at room temperature. The low temperature spectra have been used to obtain the energy...

We report on crystal growth and fluorescence characterization of Yb3+ doped NdPO4 single crystals. From the analysis of fluorescence decay curves, the temperature dependence of Nd3+→Yb3+ and Nd3+←Yb3+ energy transfer processes has been obtained. We have found that the dominant process is strongly temperature dependent, this leading to a temperature...

Nd3+:YTa7O19 and Nd3+:LaTa7O19 crystals were grown by spontaneous nucleation using a K2Mo3O10–B2O3 flux. The absorption and emission spectra were measured at 10 and 300 K. The low temperature spectra evidence the presence of non-equivalent optical centres, whose origin is discussed on the basis of the structural data. The room temperature spectra s...