Aleksandr Oreshonkov

Russian Academy of Sciences | RAS · Kirensky Institute of Physics; Siberian Branch

Praseodymium sulfate was obtained by the precipitation method and the crystal structure was determined by Rietveld analysis. Pr2(SO4)3 is crystallized in the monoclinic structure, space group C2/c, with cell parameters a = 21.6052 (4), b = 6.7237 (1) and c = 6.9777 (1) Å, β = 107.9148 (7)°, Z = 4, V = 964.48 (3) Å3 (T = 150 °C). The thermal expansi...

Two-dimensional transition metal dichalcogenides (TMDs) with Janus structures are attracting increasing attention due to their emerging superior properties in breaking vertical mirror symmetry when compared to conventional TMDs, which can be beneficial in fields such as piezoelectricity and photocatalysis. The structural investigations of such mate...

The growing families of two-dimensional crystals derived from naturally occurring van der Waals materials offer an unprecedented platform to investigate elusive physical phenomena and could be of use in a diverse range of devices. Of particular interest are recently reported atomic sheets of non-van der Waals materials, which could allow a better c...

In the present work, we report on the synthesis of EuSO4 powders by two different methods using EuS as starting material. The compound EuSO4 contains divalent europium and crystallizes in the orthorhombic crystal system, space group Pnma with parameters close to SrSO4. The compound exhibits near isotropic thermal expansion over the temperature rang...

New noncentrosymmetric alkali rare-earth double borate Rb3SmB6O12 was found in the ternary system Rb2O–Sm2O3–B2O3. The Rb3SmB6O12 powder was prepared by the solid state reaction method at 750 °C for 40 h and the crystal structure was obtained by the Rietveld method. Rb3SmB6O12 crystallized in space group R32 with unit cell parameters a = 13.4874 (3...

This summary is a review on articles published in the Special Issue “Advances in Density Functional Theory (DFT) Studies of Solids” from the section “Materials Simulation and Design” of the MDPI journal Materials. Nowadays, the DFT method is widely used to calculate structural, electronic, optical, vibrational, etc., properties of materials. There...

Cesanite (Ca2Na3(OH)(SO4)3), a rare mineral, has been found in a few places restricted to a geothermal field and caves. We report the new occurrence of cesanite in quite different geological site—within sulfate-rich melt inclusions in chloride segregations from kimberlites of Udachnaya-East pipe (Siberia). Two halite generations: сesanite free and...

In this work, we report on the synthesis, in-depth crystal structure studies as well as optical and magnetic properties of newly synthesized heterometallic quaternary selenides of the Eu+2Ln+3Cu+1Se3 composition. Crystal structures of the obtained compounds were refined by the derivative difference minimization (DDM) method from the powder X-ray di...

A set of new triple molybdates, LixNa1-xCaGd0.5(MoO4)3:Ho3+0.05/Yb3+0.45, was successfully manufactured by the microwave-accompanied sol–gel-based process (MAS). Yellow molybdate phosphors LixNa1-xCaGd0.5(MoO4)3:Ho3+0.05/Yb3+0.45 with variation of the LixNa1-x (x = 0, 0.05, 0.1, 0.2, 0.3) ratio under constant doping amounts of Ho3+ = 0.05 and Yb3+...

Samarium-sodium double sulfate crystalline hydrate NaSm(SO4)2·H2O was obtained by the crystallization from an aqueous solution containing equimolar amounts of ions. The anhydrous salt of NaSm(SO4)2 was formed by a thermally induced release of the equivalent of water from NaSm(SO4)2·H2O. The kinetic parameters of thermal decomposition were determine...

In the present work, we report on the synthesis of Sc2S3, ScCuS2 and BaScCuS3 powders using a method based on oxides sulfidation and modification of their properties. The crystal structures and morphology of the samples are verified by XRD and SEM techniques. Thermal stability has been studied by DTA which has revealed that Sc2S3 decomposes to ScS...

Crystalline hydrate of double cesium europium sulfate [CsEu(H2O)3(SO4)2]·H2O was synthesized by the crystallization from an aqueous solution containing equimolar amounts of 1Cs+:1Eu3+:2SO42− ions. Anhydrous salt CsEu(SO4)2 was formed as a result of the thermal dehydration of the crystallohydrate. The unusual effects observed during the thermal dehy...

Free access link: https://authors.elsevier.com/c/1cqD45pgla2EO Complex sulfides BaDyCuS3, BaHoCuS3 and BaYbCuS3 were synthesized in a flow of sulfiding gases (CS2, H2S) at 900оC from standard solutions of lanthanide and copper nitrates, as well as from the same standard Ba(OH)2 solution. The crystal structures of BaDyCuS3, BaHoCuS3 and BaYbCuS3 we...

A double holmium-silver sulfate was obtained for the first time. The temperature intervals for the formation and stability of the compound were determined by differential scanning calorimetry. The crystal structure of AgHo(SO4)2 was determined by Rietveld method. The X-ray diffraction (XRD) analysis showed that the compound crystallizes in the mono...

The traditional way for determination of molecular groups structure in crystals is the X-Ray diffraction analysis and it is based on an estimation of the interatomic distances. Here, we report the analysis of structural units in Y2O2SO4 using density functional theory calculations of electronic properties, lattice dynamics and experimental vibratio...

In order to synthesize single crystals of europium-silver double sulfate monohydrate, a hydrothermal reaction route was used. It was found that the crystallization cannot be performed under standard conditions. The compound AgEu(SO4)2·H2O crystallizes in the trigonal crystal system, space group P3221 (a = 6.917(1), c = 12.996(2) Å, V = 538.53(17) Å...

BaLaCuS3 powder was prepared by sulphidation method. The shape of powder particles is irregular and place in the range of 10–100 μm. The electronic, elastic and vibrational properties were evaluated with the use of DFT method. According to the electronic band structure calculation the BaLaCuS3 is a direct wide band gap semiconductor with Edg = 2.0...

Solid solutions of oxysulfides (RE 0.95 Ln 0.05) 2 O 2 S (RE ¼ La, Y; Ln ¼ Ho, Tm) were obtained by hydrogen reduction of the co-precipitated sulfates followed by sulfidation of the reaction products. The crystal chemical characteristics of the obtained compounds were refined by the Rietveld method. Morphological certification of particles in the d...

Solid daughter phases in fluid and salt melt inclusions in minerals provide important clues to characterization of mineral‐forming processes. The analysis of the fluid inclusions often requires the exposure of the daughter minerals. Rinneite (K3NaFeCl6), which is a hygroscopic mineral, decomposes in air and cannot thus be identified by conventional...

AgGd(MoO 4) 2 :Ho 3+ /Yb 3+ double molybdates with five concentrations of Ho 3+ and Yb 3+ were synthesized by the microwave employed sol-gel based process (MES), and the crystal structure variation, concentration effects, and spectroscopic characteristics were investigated. The crystal structures of AgGd 1-x-y Ho x Yb y (MoO 4) 2 (x = 0, 0.05; y =...

3.65 Å-phase (or hydroxide-perovskite), MgSi(OH)6, is a representative of dense hydrous magnesium silicates (DHMS) with maximum water content (up to ∼35 wt.% H2O) and thus is of interest as one of the largest repositories of water among all the known hydrous phases. Sample of 3.65 Å-phase, grown in DIA-type multianvil apparatus, was studied by Rama...

The phase relations in the subsolidus region of the Tl2MoO4−Bi2(MoO4)3−Hf(MoO4)2 system were studied with the "intersecting cuts" method. The formation of the novel ternary molybdate Tl5BiHf(MoO4)6 is found in this ternary system. The compound has a phase transition at Tpt = 731 K (ΔH = −3.15 J/g) and melts at Tm = 871 K (ΔH = −41.71 J/g), as deter...

Single crystals of SmAl3(BO3)4 were synthesized by the group growth on seeds method. The crystal structure was solved using a single-crystal experiment and the purity of the bulk material was proved by the Rietveld method. This borate crystallizes in the monoclinic C2/c space group with unit-cell parameters a = 7.2386 (3), b = 9.3412 (5), c = 11.10...

Table S1 Main crystallographic parameters of monoclinic ReAl3(BO3)4 compounds. Table S2 Main parameters of processing and refinement of the SmAl3(BO3)4 sample. Table S3 Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2). Table S4 The main bond lengths (Å) of compound SmAl3(BO3)4. Figure S1 Difference X-...

Free access link: https://authors.elsevier.com/c/1aZyl3IWkbyXKh Abstract: New ternary molybdate NaPbLa(1-x-y)(MoO4)3:xEr3+ ,yYb3+ (x = y = 0, x = 0.05 and y = 0.35, 0.4, 0.45 and 0.5) phosphors were successfully fabricated by the MSG (microwave sol-gel) method, and the microstructural and spectroscopic properties were characterized. The crystal s...

The oxidation process of samariumoxysulfide was studied in the temperature range of 500–1000 °C. Our DTA investigation allowed for establishing the main thermodynamic (∆Hºexp = −654.6 kJ/mol) and kinetic characteristics of the process (Ea = 244 kJ/mol, A = 2 × 1010). The enthalpy value of samarium oxysulfate (ΔHºf (Sm2O2SO4(monocl)) = −2294.0 kJ/mo...

In the present study, the unit cell parameters and atomic coordinates are predicted for the Pbcm orthorhombic structure of Si(oP32) modification. This new allotrope of silicon is mechanically stable and stable with respect to the phonon states. The electronic structure of Si(oP32) is calculated for LDA and HSE06 optimized structures. The band gap v...

The crystal structure of YAl3(BO3)4 is obtained by Rietveld refinement analysis in the present study. The dynamical properties are studied both theoretically and experimentally. The experimental Raman and Infrared spectra are interpreted using the results of ab initio calculations within density functional theory. The phonon band gap in the Infrare...

New triple tungstate phosphors NaPbLa(WO 4) 3 :Yb 3+ /Ho 3+ (x = Yb 3+ /Ho 3+ = 7, 8, 9, 10) are successfully fabricated by microwave assisted sol-gel synthesis and their structural and frequency upconversion (UC) characteristics are investigated. The compounds crystallized in the tetragonal space group I4 1 /a and the NaPbLa(WO 4) 3 host have unit...

The process of high-temperature oxidation of EuS in the air was explored in the temperature range of 500-1000 °C. The oxidation reaction enthalpy was determined (ΔH0exp=―1718.5 kJ/mol). The study of oxidation products allowed to establish the mechanism of EuS oxidation with oxygen. At 500-600 °C, EuS is oxidized to a mixture of Eu3+-containing comp...

Low frequency Raman spectra of (Pb[Formula: see text]La[Formula: see text](Zr[Formula: see text]Sn[Formula: see text]Ti[Formula: see text]O 3 ceramic samples have been studied near cubic to antiferroelectric phase transition at about 200 ∘ C. A set of low frequency soft modes were observed restoring below the transition point, in addition to the kn...

RbEu(MoO4)2 is synthesized by the two-step solid state reaction method. The crystal structure of RbEu(MoO4)2 is defined by Rietveld analysis in space group Pbcn with cell parameters a = 5.13502(5), b = 18.8581(2) and c = 8.12849(7) Å, V = 787.13(1) Å3, Z = 4 (RB = 0.86%). This molybdate possesses its phase transition at 817 K and melts at 1250 K. T...

Rigorous peer-review is the corner-stone of high-quality academic publishing. The editorial team greatly appreciates the reviewers who contributed their knowledge and expertise to the journal’s editorial process over the past 12 months. In 2018, a total of 478 papers were published in the journal, with a median time to first decision of 14 days and...

Eu2(SO4)3 was synthesized by chemical precipitation method and the crystal structure was determined by Rietveld analysis. The compound crystallizes in monoclinic space group С2/с. In the air environment, Eu2(SO4)3 is stable up to 670 °C. The sample of Eu2(SO4)3 was examined by Raman, Fourier-transform infrared absorption and luminescence spectrosco...

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Silver-europium double sulfate AgEu(SO4)2 was obtained by solid-phase reaction between Ag2SO4 and Eu2(SO4)3. The crystal structure of AgEu(SO4)2 was determined by Monte Carlo method with simulated annealing, and after that, it was refined by the Rietveld method from X-ray powder diffraction data. The compound crystallizes in the triclinic symmetry,...

Anhydrous chlorides - CaCl2, and KCaCl3 (chlorocalcite) were identified as mineral inclusions in halite from the Siberian Large Igneous Province at the contact of magmatic intrusions and evaporates. Chlorocalcite was also found as daughter mineral in polyphase hypersaline inclusions. While Raman spectra of KCaCl3 (chlorocalcite) in natural inclusio...

Crystal structure of LaF3 single crystal is refined in tysonite-type trigonal unit cell P-3c1 using density functional theory calculations and Raman spectroscopy. It is shown that trigonal structure with P-3c1 space group is more energy-efficient than hexagonal structure with space group P63cm. Simulated Raman spectra obtained using LDA approximati...

Raman spectra of (NH4)3TiF7 within spectral range 10–3,400 cm−1 at temperatures 8–370 K are recorded, which revealed 2 phase transitions at temperatures T1 = 355 K and T2 = 283 K. First principles calculations of lattice dynamics and assignment of the observed lines to specific vibrational types are performed. The first phase transition is classifi...

Link for free download up to February 09, 2018: https://authors.elsevier.com/c/1WFxby3Zws41v . New noncentrosymmetric double borate Rb3EuB6O12 was designed and synthesized by the solid state reaction method, and its crystallographic parameters were obtained by Rietveld analysis. This borate crystallizes in the trigonal space group R32 with cell pa...

The crystal structure of new monoclinic molybdate BaSm2(MoO4)4 is refined in monoclinic unit cell C2/m with cell parameters a = 5.29448 Å, b = 12.7232 Å, c = 19.3907 Å, β = 91.2812°, V = 1305.89 ų. The crystal structure consists of the SmO8 square antiprism joined with each other by the edges forming a 2D layer perpendicular to the c-axis. MoO4 te...

BiB3O6 crystal has been characterized by Raman spectroscopy. Polarized low-frequency spectra have been obtained. Temperature measurements have been carried out in range 7–350 K. Raman spectra have been numerically simulated with lady software package. The results of experiment confirmed the contribution of the Bi³⁺ ions and BO4 groups in nonlinear...

Two ammonium oxofluorovanadates, (NH4)3VO2F4 and (NH4)3VOF5, have been investigated by temperature-dependent infrared and Raman spectroscopy methods to determine the nature of phase transitions (PT) in these compounds. Dynamics of quasioctahedral groups was simulated within the framework of semi-empirical approach, which justified the cis-conformat...

Ternary scheelite-type molybdate NaSrLa(1-x-y)(MoO4)3:xEr³⁺,yYb³⁺ (x = y = 0, x = 0.1 and y = 0.2, x = 0.05 and y = 0.45, x = 0.2 and y = 0) phosphors were successfully synthesized by the microwave sol-gel method for the first time. Well-crystallized particles formed after the heat-treatment at 900 °C for 16 h showed a fine and homogeneous morpholo...

CaGd2(MoO4)4:Ho3+/Yb3+ phosphors doped by Ho3+ and Yb3+ (Ho3+ = 0 and 0.05, and Yb3+ = 0, 0.35, 0.40, 0.45 and 0.50) were successfully synthesized by the microwave sol-gel method. The synthesized particles, being formed after heat-treatment at 900 °C for 16 h, showed a well crystallized morphology. All compounds are (3 + 2)D incommensurately modula...

Gadolinium manganese sulfide solid solutions are investigated by infrared and Raman spectroscopy. Longitudinal optical–transverse optical splitting of the manganese–sulfur bond vibration is observed in vibrational spectra. The Raman spectra contain modes that are prohibited in crystal structure of alpha phase of manganese sulfide, which are associa...

New noncentrosymmetric rare earth borate Rb3NdB6O12 is found in the ternary system Rb2O–Nd2O3–B2O3. The Rb3NdB6O12 powder was fabricated by solid state synthesis at 1050 K for 72 h and the crystal structure was obtained by the Rietveld method. Rb3NdB6O12 crystallized in space group R32 with unit cell parameters a = 13.5236(4), c = 31.162(1) Å, Z =...

This work is devoted to the complex research of temperature phase transitions in CsScF4 crystal. Crystal structure was solved and refined at different temperatures by Rietveld method. Structural phase transitions were investigated by spectroscopic methods some of them for the first time: Brillouin spectroscopy, Raman spectroscopy, IR absorption spe...

The vibrational spectroscopy has been applied to investigate the structure the BiB3O6 (BIBO) crystal. Based on the experimental results, the total set of phonons mode of the polarized Raman spectra was proposed. To verify the obtained experimental data have been performed theoretical calculation in software package LADY.

The vibrational spectroscopy investigation of phase transitions in NdF3 crystal is reported. Spectra were obtained in temperature range from 300 to 10 K. It has been shown that, down to 10 K, the trigonal tysonite structure of NdF3 trifluoride remains stable.

The total set of polarized Raman spectra have been obtained at room temperature, and an assignment of observed modes based on the lattice dynamics simulation and polarization selection rules is proposed. An LO-TO splitting of A1 Raman bands have been observed.

Triple molybdate NaCaLa(1-x-y)(MoO4)3:xEr³⁺,yYb³⁺ (x = y = 0, x = 0.05 and y = 0.45, x = 0.1 and y = 0.2, x = 0.2 and y = 0) phosphors were successfully synthesized for the first time by the microwave sol-gel method. Well-crystallized particles formed after heat treatment at 900 °C for 16 h showed a fine and homogeneous morphology with particle siz...

MnGeO3 single-crystal samples have been synthesized by optical zonal melting and spontaneous crystallization. X-ray crystal analysis showed the first sample to be a two-phase one with phase ratio as follows: 17% – monoclinic C2/c, and 83% – orthorhombic Pbca; the phase ratio of the second sample was unknown. Raman spectra have been produced for the...

The structural phase transition in the Pr 3 Sb 5 O 12 crystal has been studied using Raman spectros-copy. The phase transition is accompanied by the recovery of the soft mode below T = 735 K, which is associated with the displacements of the oxygen and antimony atoms.

Infrared absorption spectra of a Nd0.5Ho0.5Fe3(BO3)4 crystal in the spectral range of 30–1700 cm–1 have been measured at temperatures from 6 to 300 K. The experimental spectra have been analyzed based on the semiempirical calculation of the lattice dynamics and the analysis of correlation diagrams of borate complexes. No changes associated with str...

Raman spectroscopy investigation of phase transition in Pr3Sb5O12 crystal is reported. Spectra were obtained in temperature range from 300 to 800 K. Soft mode restoration has been found below 735 K, that allows to attribute structural phase transition as displacive.

The structural phase transition in the Pr3Sb5O12 crystal has been studied using Raman spectroscopy. The phase transition is accompanied by the recovery of the soft mode below T = 735 K, which is associated with the displacements of the oxygen and antimony atoms.

CaGd2(MoO4)4:Er3+/Yb3+ phosphors with the doping concentrations of Er3+ and Yb3+ (x = Er3+ + Yb3+, Er3+ = 0.05, 0.1, 0.2, and Yb3+ = 0.2, 0.45) have been successfully synthesized by the microwave sol–gel method, and the crystal structure refinement and upconversion photoluminescence properties have been investigated. The synthesized particles, bein...

CaLa2-x(MoO4)4:Ho3+/Yb3+ phosphors with the doping concentrations of Ho3+ and Yb3+ (x = Ho3+ + Yb3+, Ho3+ = 0.05; Yb3+= 0.35, 0.40, 0.45 and 0.50) have been successfully synthesized by the microwave sol-gel method. The modulated and averaged crystal structures of CaLa2-x(MoO4)4:Ho3+/Yb3+ molybdates have been found by Rietveld method, and the upconv...