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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 diffraction data. The structures are found to belong to orthorhombic space groups Pnma (structure type Ba2MnS3 for EuLaCuSe3 and structure type Eu2CuS3 for EuLnCuSe3, where Ln = Sm, Gd, Tb, Dy, Ho and Y) and Cmcm (structure type KZrCuS3 for EuLnCuSe3, where Ln = Tm, Yb and Lu). Space groups Pnma and Cmcm were delimited based on the tolerance factor t’, and vibrational spectroscopy additionally confirmed the formation of three structural types. With a decrease in the ionic radius of Ln3+ in the reported structures, the distortion of the (LnCuSe3) layers decreases, and a gradual formation of the more symmetric structure occurs in the sequence Ba2MnS3 → Eu2CuS3 → KZrCuS3. According to magnetic studies, compounds EuLnCuSe3 (Ln = Tb, Dy, Ho and Tm) each exhibit ferrimagnetic properties with transition temperatures ranging from 4.7 to 6.3 K. A negative magnetization effect is observed for compound EuHoCuSe3 at temperatures below 4.8 K. The magnetic properties of the discussed selenides and isostructural sulfides were compared. The direct optical band gaps for EuLnCuSe3, subtracted from the corresponding diffuse reflectance spectra, were found to be 1.87– 2.09 eV. Deviation between experimental and calculated band gaps is ascribed to lower d states of Eu2+ in the crystal field of EuLnCuSe3, while anomalous narrowing of the band gap of EuYbCuSe3 is explained by the low-lying charge-transfer state. Ab initio calculations of the crystal structures, elastic properties and phonon spectra of the reported compounds were performed. © 2022 by the authors. Licensee MDPI, Basel, Switzerland. Funding: The research was supported by the Tyumen region within the framework of the grant agreement in the form of a grant to non-profit organizations no. 89-don dated 07.12.2020. This study was supported by the Ministry of Science and Higher Education of the Russian Federation (project no. FEUZ-2020-0054). This work was supported by state assignment of the Ministry of Science and Higher Education of the Russian Federation (Project Reg. No. 720000Ф.99.1.БЗ85АА13000). The work was conducted within the framework of the budget project № 0287-2021-0013 for the Institute of Chemistry and Chemical Technology SB RAS.

The crystal structures of three polymorphs of Rb3ScF6 have been determined through a combination of synchrotron, laboratory X-ray, and neutron powder diffraction, electron diffraction, and multinuclear high-field solid-state NMR studies. The room temperature (RT; α) and medium-temperature (β) structures are tetragonal, with space groups I41/a (Z = 80) and I4/m (Z = 10) and lattice parameters a = 20.2561(4) Å, c = 36.5160(0) Å and a = 14.4093(2) Å, c = 9.2015(1) Å at RT and 187 °C, respectively. The high-temperature (γ) structure is cubic space group Fm3¯ m (Z = 4) with a = 9.1944(1) Å at 250 °C. The temperatures of the phase transitions were measured at 141 and 201 °C. The three α, β, and γRb3ScF6 phases are isostructural with the α, β, and δforms of the potassium cryolite. Detailed structural characterizations were performed by density functional theory as well as NMR. In the case of the β polymorph, the dynamic rotations of the ScF6 octahedra of both Sc crystallographic sites have been detailed. © 2021 American Chemical Society. For DFT calculations, we thank the “Centre de Calcul Scientifique en region Centre” (Orléans, France). We acknowledge the Interface, Confinement, Materials and Nanostructures (Orléans, France) for access to their transmission electron microscope. Financial support from the IR-RMN-THC Fr3050 CNRS for conducting the research is gratefully acknowledged. This study was also financially supported by VEGA-2/0060/18 and ITMS project (code 313021T081, Research & Innovation Operational Programme funded by the ERDF). We thank also Dr. F. Vivet, Dr. F. Fayon, and Dr. D. Massiot for useful discussions.

Pb9R(GeO4)3(VO4)3 (R=Tb, Dy, Ho) apatites were obtained by solid-phase synthesis from the initial oxides of PbO, Tb2O3 (Dy2O3, Ho2O3), GeO2 and V2O5 by sequential annealing (at a temperature of 773-1073 K) in an air atmosphere. Their crystal structure has been determined by X-ray diffraction analysis. The high-temperature heat capacity was measured by differential scanning calorimetry. Based on the experimental dependence of the heat capacity on the temperature, the thermodynamic properties are calculated. Keywords: apatites, solid-phase synthesis, crystal structure, heat capacity, thermodynamic properties. Keywords: apatites, solid-phase synthesis, crystal structure, heat capacity, thermodynamic properties.

Apatite Pb3Bi2(GeO_4)3 was obtained by the solid-phase method from the initial oxides of PbO, Bi2O3 and GeO2 by sequential firing in air at temperatures of 773-1003 K. Its crystal structure has been refined by X-ray diffraction. The high-temperature heat capacity (350-1000 K) of this compound was measured by differential scanning calorimetry. Based on these data, the main thermodynamic functions are calculated. Keywords: apatite bismuth-lead germanate, solid-phase synthesis, high-temperature heat capacity, thermodynamic properties Keywords: apatite bismuth-lead germanate, solid-phase synthesis, high-temperature heat capacity, thermodynamic properties.

Copper-europium germanate CuEu2Ge2O8 was obtained from the initial CuO, Eu2O3 and GeO2 oxides using solid-phase synthesis by annealing in air in the temperature range of 1223-1273 K. Its crystal structure was determined (space group Cm). The influence of temperature on high-temperature heat capacity of the synthesized germanate was studied by the differential scanning calorimetry method. It was found that the dependence of heat capacity on temperature has an extreme value related to a phase transition. The thermodynamic properties were calculated based on the experimental data about heat capacity. Keywords: copper-europium germanate, solid-phase synthesis, crystal structure, thermodynamic properties.

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала. The colorless crystals of 1,3-diethyl-7-hydroxy-5,5,7-trimethy1-2-thioxo-1,2,3,5,6,7-hexahydro-4H-pyrano[2,3-d]pyrimidin-4-one (I) have been crystallized from the solution containing 1,3-diethyl-2-thiobarbituric acid (HDETBA) and equal volumes of concentrated HCl and acetone A possible stoichiometric reaction mechanism has been suggested. The crystal structure of I has been determined by X-ray single crystal analysis. The phase purity of the precipitate has been verified by powder X-ray diffraction analysis. Compound 1 crystallizes in the orthorhombic structure, space group P2(1)2(1)2(1), with cell parameters a = 9.7454(4), b = 11.2225(4), c = 13.9171(5) angstrom, Z = 4, V = 1522.1(1) angstrom(3). The molecules of 1 contain the bicyclic ring constructions new in thiobarbiturates. The molecules of 1 are linked by O-H center dot center dot center dot O hydrogen bonds to infinite molecule chains. The results of mass spectrometric analysis, theoretical studies and IR spectroscopy confirm the structure of I. Using the PASS software, the general pharmacological potential of 1 was analyzed. (C) 2015 Elsevier B.V. All rights reserved.

The conditions for the flux growth of new Mn-Ni oxyborates with the ludwigite structure are reported. Magnetic measurement data for the samples with nickel and manganese predominance are presented. Diamagnetic anomalies of the antiferromagnetic phases are established and analyzed in the framework of a model comprising two antiferromagnetically interacting subsystems, each being antiferromagnetically ordered., 11 figures, 3 tables