共查询到20条相似文献,搜索用时 31 毫秒
1.
E. V. Selezneva I. P. Makarova V. V. Grebenev V. A. Komornikov 《Crystallography Reports》2018,63(2):178-185
The structure of (K0.967(NH4)0.033)3H(SO4)2 crystals, belonging to the K3H(SO4)2–(NH4)3H(SO4)2–H2O salt system, has been investigated by X-ray structural analysis. The room-temperature characteristics of the atomic structure of these crystals are found to be as follows: sp. gr. C2/c, Z = 4, a = 14.7025(4) Å, b = 5.6859(2) Å, c = 9.7885(3) Å, and R/wR = 0.021/0.030%. The thermal and optical properties of (K,NH4)3H(SO4)2 and K3H(SO4)2 single crystals have been investigated and compared in a temperature range of 295–500 K. 相似文献
2.
The crystal structure of the new compound Rb2[Ti(VO2)3(PO4)3] obtained by hydrothermal synthesis in the RbCl-TiPO4-V2O5-B2O3-H2O system (a = 13.604(2) Å, c = 9.386(2) Å, sp. gr. P6cc, Z = 4, ρcalcd = 3.32 g/cm3) has been studied by X-ray diffraction (Xcalibur-S-CCD diffractometer, R = 0.038). It is shown that the isotypism of Rb2[Ti(VO2)3(PO4)3] and Cs2[Ti(VO2)3(PO4)3] is caused by the flexibility of a mixed anionic framework composed of phosphorus tetrahedra, vanadium five-vertex polyhedra, and titanium octahedra (bases of the crystal structures of these compounds). The topological correlations between the structures of titanium-vanadyl phosphates and benitoite and beryl silicates are analyzed. 相似文献
3.
V. A. Komornikov A. M. Grechikhina V. V. Grebenev I. S. Timakov O. B. Zajnullin V. G. Zinoviev 《Crystallography Reports》2018,63(5):806-811
Proton-conducting composites xCs4(HSO4)3(H2PO4) + (1–x)AlPO4 in the composition range x = 0.9–0.5 have been obtained. Their transport properties are studied by impedance spectroscopy. The dependences of the phase composition of the materials on the component ratio are investigated by X-ray diffraction analysis. The spatial phase distribution in the materials is analyzed using scanning electron microscopy. 相似文献
4.
M. V. Sukhanov E. R. Gobechiya Yu. K. Kabalov V. I. Pet’kov 《Crystallography Reports》2008,53(6):974-980
New lithium-niobium and lithium-tantalum phosphates Li1/4 M 7/4(PO4)3(M = Nb, Ta) are synthesized by the solid-phase method. The compounds prepared are characterized using electron microprobe analysis, X-ray powder diffraction, and IR spectroscopy. The crystal structure of the Li1/4Ta7/4(PO4)3 phosphate is determined from the X-ray powder diffraction data (the Rietveld method) and belongs to the framework type. The framework of the structure consists of TaO6 and LiO6 vertex-shared octahedra and PO4 tetrahedra. The isostructural phosphates Li1/4 M 7/4(PO4)3 crystallize in the trigonal crystal system (space group R \(\bar 3\) c, Z = 6) and belong to the NaZr2(PO4)3 structure type. 相似文献
5.
E. R. Gobechiya Yu. K. Kabalov S. V. Tomilin A. N. Lukinykh A. A. Lizin A. I. Orlova 《Crystallography Reports》2005,50(3):374-378
The crystal structure of the high-temperature β modification of synthetic orthophosphate KU2(PO4)3 was refined from powder X-ray diffraction data by the Rietveld method: sp. gr. \(R\bar 3c\), the unit-cell parameters a= 9.113(1) Å and c= 24.997(1) Å. The isotropic refinement converged to R wp = 6.15, R B = 2.14, R F = 3.52, and S = 0.42. It was confirmed that β-KU2(PO4)3 belongs to the structure type of sodium zirconium phosphate containing an actinide atom in a sixfold (octahedral) coordination formed by oxygen atoms, which is unusual for orthophosphates. The principal interatomic distances and bond angles in the structure are reported. 相似文献
6.
The mixed tris-cyclopentadienyl tetrahydrofuranato samarium complex bis-(cyclopentadienyl) methylcyclopentadienyl tetrahydrofuranato samarium (I) was synthesized by reaction of (C5H5)2SmCl with methyl cyclopentadienyl sodium in THF. [(C5H5)2(C5H4CH3)(C4H8O)Sm] (I) was characterized by elemental analyses—IR spectra and MS spectra. The structure of [(C5H5)2(C5H4CH3)(C4H8O)Sm] (I), which has two slightly different independent molecules per asymmetric unit, has been elucidated through complete X-ray analysis. The crystals are monoclinic, with a = 12.791(3) Å, b = 10.467(2) Å, c = 26.108(5) Å, β = 98.22(2)°, and space group Cc, R = 0.0381 for 2103 observed-reflection with I ≥ 3σ(I). 相似文献
7.
The crystal structure of synthetic manganese sodium borophosphate hydrate Na(H2O)[Mn(H2O)2(BP2O8)] was refined based on X-ray diffraction data. The compound was prepared by soft hydrothermal synthesis in the MnCl2-Na3PO4-B2O3-H2O system. The unit-cell parameters are a= 9.602(1) Å, c= 16.037(3) Å, sp. gr. P6522, Z= 6, D x = 2.57 g/cm3. The water molecules were found to be statistically distributed in the channels of the mixed anionic paraframework consisting of (BO4) and (PO4) tetrahedra and [MnO4(H2O)2] octahedra. The hydrogen atoms of the water molecules coordinated to the Mn2+ cations were located and their positional and thermal parameters were refined. The crystal-chemical features of borophosphates of the general formula A x M(H2O)2(BP2O8)(H2O) are considered. 相似文献
8.
E. V. Selezneva I. P. Makarova V. V. Grebenev I. A. Malyshkina V. A. Komornikov N. D. Gavrilova R. Chitra R. R. Choudhury 《Crystallography Reports》2018,63(4):553-562
The structure of (K1–x(NH4)x)3H(SO4)2 crystals with a low ammonium concentration and the behavior of their thermal, optical, and dielectric properties in a temperature range of 275–500 K have been investigated to clarify the influence of doping on the phase transition kinetics. An examination of unit-cell parameters of (K1 – x(NH4)x)3H(SO4)2 single crystals has confirmed the existence of a superprotonic phase transition at a temperature of ≈450K. The conducting properties of single-crystal and polycrystalline samples have been studied. 相似文献
9.
V. Y. Stadnyk M. O. Romanyuk M. R. Tuzyak V. Y. Kurlyak V. M. Gaba 《Crystallography Reports》2008,53(6):1039-1043
The influence of uniaxial mechanical pressure σ m ≤ 150 bar on the spectral (300–800 nm) dependence of the birefringence Δn i of (NH4)2SO4 crystals is studied. The dispersion Δn i (λ) is shown to be normal and greatly increases when approaching the absorption edge. Uniaxial pressure changes the value of dispersion dΔn i /dλ but not its character. It is found that the simultaneous action of pressures σ x ~ σ y ~ 560 bar results in the occurrence of a uniaxial isotropic state. Piezoelectric constants of the crystals are estimated. 相似文献
10.
The crystal structure of new manganese potassium copper vanadate KCuMn3(VO4)3, which was prepared by the hydrothermal synthesis in the K2CO3–CuO–MnCl2–V2O5–H2O system, was studied by X-ray diffraction (R = 0.0355): a = 12.396(1) Å, b = 12.944(1) Å, c = 6.9786(5) Å, β = 112.723(1)°, sp. gr. C2/c, Z = 4, ρcalc = 3.938 g/cm3. A comparative analysis of the crystal-chemical features of the new representative of the alluaudite family and related structures of minerals and synthetic phosphates, arsenates, and vanadates of the general formula A(1)A(1)′A(1)″A(2)A(2)′M(1)M(2)2(TO4)3 (where A are sites in the channels of the framework composed of MО6 octahedra and TО4 tetrahedra) was performed. A classification of these structures into subgroups according to the occupancy of A sites is suggested. 相似文献
11.
The crystal structure of two borophosphates, Rb(Al,Fe)[BP2O8(OH)] (a = 9.381(6), b = 8.398(5), c = 9.579(6) Å, β = 102.605(10)°, sp. gr. P21/c) and K(Fe,Al)[BP2O8(OH)] (a = 5.139(2), b = 8.065(4), c = 8.290(4)Å, α = 86.841(8)°, β = 80.346(8)°, γ = 86.622(8)°, sp. gr. P \(\bar 1\)), obtained by hydrothermal synthesis in the AlCl3: FeCl3: K3PO4(Rb3PO4): B2O3: H2O system has been established using X-ray diffraction (Bruker Smart diffractometer, T = 100 K). Hydrogen atoms are located and their coordinates and thermal parameters are refined. It is shown that the polymorphism of the [BP2O8(OH)]4? borophosphate anion has a morphotropic nature and is related to the substitutions both in the cationic part of the structure and in the octahedral position of the anionic mixed framework. The synthesis of new isotypic triclinic compounds under hydrothermal conditions is predicted. 相似文献
12.
N. I. Sorokin 《Crystallography Reports》2017,62(3):416-418
The ionic conductivity σ of KMgCr(MoO4)3 crystal has been investigated in a temperature range of 575–932 K by impedance spectroscopy in the frequency range of (5–5) × 105 Hz. Ternary molybdate was obtained from the initial MgMoO4 and KCr(MoO4)2 reagents by solid-phase technique in air at 923–973 K for 200 h. The temperature dependence σ(T) of a ceramic sample exhibits a jump of σ by a factor of about 4 at 833 ± 5 K, which is caused by the first-order phase transition. The σ value above the phase-transition temperature reaches 6 × 10–4 S/cm (932 K) at an ion-transport activation enthalpy of 0.84 ± 0.05 eV. The most likely carriers in KMgCr(MoO4)3 are K+ cations. 相似文献
13.
The crystal structure of the (Al,V)4(P4O12)3 solid solution, obtained in the single-crystal form by hydrothermal synthesis in the Al(OH)3-VO2-NaCl-H3PO4-H2O system, has been solved by X-ray diffraction analysis (Xcalibur-S-CCD diffractometer, R = 0.0257): a = 13.7477(2) Å, sp. gr. I \(\bar 4\)3d, Z = 4, and ρcalcd = 2.736 g/cm3. It is shown that the crystal structure of the parent cubic Al4(P4O12)3 modification can formally be considered an archetype for the formation of double isosymmetric tetraphosphates on its basis. 相似文献
14.
L. B. Serezhkina A. V. Vologzhanina E. O. Prudnikova V. N. Serezhkin 《Crystallography Reports》2010,55(5):780-785
Compound [UO2(C5H12N2O)5](ClO4)2 is synthesized and characterized by thermogravimetry, IR spectroscopy, and X-ray diffraction. The compound crystallizes in the monoclinic crystal system; a = 15.2985(9) Å, b = 26.9676(15) Å, c = 20.6962(11) Å, β = 100.697(1)°, space group P21/c, Z = 8, and R = 0.0445. Discrete [UO2(C5H12N2O)5]2+ groups belonging to the AM 5 1 crystal chemical group of uranyl complexes (A = UO 2 2+ and M 1=C5H12N2O) are uranium-containing structural units of the crystals. 相似文献
15.
G. V. Kiriukhina O. V. Yakubovich O. V. Dimitrova A. S. Volkov 《Crystallography Reports》2016,61(5):796-804
The crystal structure of Rb2Mn3(H2O)2[P2O7]2, a new phase obtained in the form of single crystals under hydrothermal conditions in the MnCl2–Rb3PO4–H2O system, is determined by X-ray diffraction (Xcalibur-S-CCD diffractometer, R = 0.0270): a = 9.374(2), b = 8.367(2), c = 9.437(2) Å, ß = 99.12(2)°, space group P21/c, Z = 2, Dx = 3.27 g/cm3. A correlation between the unit-cell parameters and the size of cations forming the crystal structures of isostructural A2M3(H2O)2[P2O7]2 diphosphates (A = K, NH4, Rb, or Na; M = Mn, Fe, Co, or Ni) is revealed. It is shown that, due to the topological similarity, the structures of diphosphates and orthophosphates of the farringtonite structural type can undergo mutual transformations. 相似文献
16.
A. I. Orlova S. G. Samoĭlov G. N. Kazantsev V. Yu. Volgutov D. M. Bykov A. V. Golubev E. Yu. Borovikova 《Crystallography Reports》2009,54(3):431-438
Zirconium phosphate Zr3(PO4)4 has been synthesized by the sol-gel technique and investigated using X-ray powder diffraction, IR spectroscopy, and differential scanning calorimetry. It has been established that the symmetry of the unit cell, R \(\bar 3\) c, which is characteristic of the NaZr2(PO4)3 (NZP) family, is lowered to P \(\bar 3\) c. The behavior of the zirconium phosphate during heating has been examined using high-temperature X-ray diffraction at temperatures ranging from 25 to 575°C. It has been revealed that the structure of the zirconium phosphate is hardly subjected to expansion due to heating in the temperature ranges 25–125°C (α a < 1 × 10?6 K?1, α c < 1 × 10?6 K?1, Δα < 1 × 10?6 K?1) and 325–575°C (α a = ?1.4 × 10?6 K?1, α c < 1 × 10?6 K?1, Δα < ?2.4 × 10?6 K?1). In the temperature range 125–325°C, the synthesized compound undergoes a second-order phase transition (upon heating), which is accompanied by the contraction of the structure along all crystallographic directions. Upon cooling in the range from 75 to 25°C, the phase transition is accompanied by the expansion of the structure. 相似文献
17.
A. U. Sheleg E. M. Zub A. Ya. Yachkovskii L. F. Kirpichnikova 《Crystallography Reports》2004,49(6):1028-1031
[(CH3)2NH2]5Cd3Cl11 crystals are grown by the method of isothermal evaporation from saturated aqueous solutions containing dimethylamine and cadmium chlorides, [(CH3)2NH2]Cl and CdCl2.5H2O. The crystal grown are studied by the X-ray diffraction method. It is established that the crystals are orthorhombic with the unit-cell parameters at room temperature a = 18.115 ± 0.004 Å, b = 11.432 ± 0.002 Å, and c = 15.821 ± 0.003 Å. The unit-cell parameters a, b, and c of the [(CH3)2NH2]5Cd3Cl11 crystals are measured as functions of temperature in the temperature range 100–320 K. The data obtained were used to determine the thermal expansion coefficients along the main crystallographic axes. The temperature curves of the unit-cell parameters and thermal expansion coefficients showed pronounced anomalies in the vicinity of the temperatures T 1 = 120, T 2 = 150, and T 3 = 180 K corresponding to the phase transitions in the [(CH3)2NH2]5Cd3Cl11 crystals. The crystals are also characterized by a pronounced anisotropy of thermal expansion. 相似文献
18.
M. P. Orlova D. B. Kitaev M. L. Spiridonova N. V. Zubkova Yu. K. Kabalov A. I. Orlova 《Crystallography Reports》2005,50(6):918-922
Cadmium cerium orthophosphate Cd0.5Ce2(PO4)3 is synthesized by precipitation from aqueous solutions. The structure refinement from powder X-ray diffraction data is preceded by the sample preparation and structure solution. The refinement is carried out by the Rietveld method (ADP-2 diffractometer, Cu Kα radiation, Ni filter, 15° < 2θ < 120°, 2θ-scan step 0.02°, counting time 10 s per step). All calculations are carried out using the WYRIET program (version 3.3) within the sp. gr. P21/n. The structure is refined with anisotropic displacement parameters for cations and isotropic displacement parameters for oxygen atoms. 相似文献
19.
V. I. Pet’kov V. S. Kurazhkovskaya A. I. Orlova M. L. Spiridonova 《Crystallography Reports》2002,47(5):736-743
Double phosphates of zirconium and metals with an oxidation degree of +2 of the composition M0.5Zr2(PO4)3 (M = Mg, Ca, Mn, Co, Ni, Cu, Zn, Sr, Cd, and Ba) are synthesized and characterized by X-ray diffraction methods and IR spectroscopy. The crystal structures of all the compounds are based on three-dimensional frameworks of corner-sharing PO4-tetrahedra and ZrO6-octahedra. Phosphates with large Cd2+, Ca2+, Sr2+, and Ba2+ cations octahedrally coordinated with oxygen atoms form rhombohedral structures (space group R3), whereas phosphates with small tetrahedrally coordinated Mg2+, Ni2+, Cu2+, Co2+, Zn 2+, and Mn2+-cations are monoclinic (space group P21/n). The effect of various structure-forming factors on the M0.5Zr2(PO4)3 compounds with a common structural motif but different symmetries are discussed. 相似文献
20.
L. B. Serezhkina E. V. Peresypkina N. A. Neklyudova A. V. Virovets 《Crystallography Reports》2010,55(5):769-772
The synthesis and X-ray diffraction study of compound Rb2[(UO2)2(C2O4)3], which crystallizes in the monoclinic crystal system, are performed. The unit cell parameters are as follows: a = 7.9996(6) Å, b = 8.8259(8) Å, c = 11.3220(7) Å, β = 105.394(2)°, and V = 770.7(1) Å3; space group P21/n, Z = 2, and R 1 = 0.0271. [(UO2)2(C2O4)3]2? layers belonging to the AK 0.5 02 T 11 crystal chemical group of uranyl complexes (A = UO 2 2+ , K 02 = C2O 4 2? , and T 11 = C2O 4 2? ) are uranium-containing structural units of the crystals. The layers are connected with outer-sphere rubidium cations by electrostatic interactions. 相似文献