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1.
E. L. Belokoneva A. G. Ivanova S. Yu. Stefanovich O. V. Dimitrova V. S. Kurazhkovskaya 《Crystallography Reports》2004,49(4):603-613
Crystals of new rare earth borates of the composition Ln[B6O9 (OH)3] (Ln = Sm-Lu), sp. gr. R3c are synthesized under hydrothermal conditions. Their crystal structures are determined on single crystals with Ln = Ho, Gd without preliminary determination of their chemical formulas. The polar anionic framework of the crystals consists
of BO3 triangles and BO4 tetrahedra and has wide channels along the threefold axis of the structure, which are similar to the channels along the a, b, and c axes in cubic Li4[B7O12]Cl boracite with Li conductivity. Rare earth atoms are arranged in the structure over the cubic F pseudolattice, whereas
the analogous positions in Li boracites are filled with Cl anions. The squared optical nonlinearity of the new crystals is
comparable with the nonlinearity of quartz, whereas the electrical conductivity in borates at 300°C exceeds 10−6 S/cm.
__________
Translated from Kristallografiya, Vol. 49, No. 4, 2004, pp. 681–691.
Original Russian Text Copyright ? 2004 by Belokoneva, Ivanova, Stefanovich, Dimitrova, Kurazhkovskaya. 相似文献
2.
Binary zirconium orthophosphates R1/3Zr2(PO4)3 and M1/4Zr2(PO4)3, where R = Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu; M = Th, U, have been synthesized and studied by IR spectroscopy [structural family of NaZr2(PO4)3 (NZP)]. Vibrational analysis for the PO4 tetrahedron and investigation of symmetry relations among trigonal NZP phases showed that ordering of lanthanide atoms in structures of NaZr2(PO4)3 type with space group R
c leads to symmetry reduced to P
c. The lanthanide atoms occupy the 2b sites. The phosphorus atoms occupy two independent sites: 6f with C
2 symmetry and 12g with C
1 symmetry. Factor group analysis admits that the IR spectrum can contain eight v3 bands and two v1 bands of the stretching vibrations of the PO4 ions. The M atoms of actinides occupy statistical positions in the structure, and space group R
c is retained.Original Russian Text Copyright © 2004 by V. S. Kurazhkovskaya, D. M. Bykov, and A. I. Orlova__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 6, pp. 1013–1019, November–December, 2004. 相似文献
3.
4.
E. Yu. Borovikova D. A. Ksenofontov Yu. K. Kabalov V. S. Kurazhkovskaya S. Yu. Stefanovich I. V. Korchemkin E. A. Asabina 《Crystallography Reports》2012,57(4):514-520
A complex study of the synthetic CsMgPO4 phosphate with a ??-tridymite structure type is performed. It is found that CsMgPO4 is an unstable phase. At room temperature in air, it absorbs water and turns into the CsMgPO4 · 6H2O crystal hydrate. The transformation of cubic CsMgPO4 · 6H2O into orthorhombic CsMgPO4 proceeds upon heating to 150°C by the pattern of the first-order phase transition with the dehydration of the specimen. 相似文献
5.
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
6.
E.A. Asabina D.A. Rusakov V.S. Kurazhkovskaya 《Journal of solid state chemistry》2010,183(9):1980-1984
The incorporation possibilities of different alkali elements into crystalline phosphates A1−xA′xHf2(PO4)3 (A=Li, Na, K, Rb, Cs) were studied, the formation regions of kosnarite solid solutions were determined. Na0.5K0.5Hf2(PO4)3 crystal structure was studied by powder X-ray diffraction, and the distribution of alkali metals in kosnarite structure was found out. The phosphate crystallizes in the space group R3?c, with a=8.7295(1) Å, c=23.2023(4) Å, V=1531.24(4) Å3, Z=6; Rwp=6.15, Rp=4.43. The concentration region knowledge of the kosnarite phase existence and peculiarities of their phase formation in the A1−xA′xM2(PO4)3 (M=Ti, Zr, Hf) systems allow us to choose phosphate matrice compositions suitable for solidification of reprocessing wastes of spent U-Pu nuclear fuels. 相似文献
7.
V. I. Pet’kov I. A. Shchelokov V. S. Kurazhkovskaya N. V. Orekhova M. M. Ermilova G. F. Tereshchenko 《Russian Journal of Inorganic Chemistry》2008,53(7):993-999
Complex phosphates of titanium, chromium, and metals(2+) of the general formula M0.5(1 + x )Cr x Ti2 ? x (PO4)3 (M = Mg, Ca, Mn, Ni, Sr, Ba, and Pb) were synthesized. Their phase formation was studied by means of X-ray powder diffraction, electron probe microanalysis, differential thermal analysis, and IR spectroscopy. Individual phases and solid solutions crystallizing in kosnarite and langbeinite structure types were identified; their crystallographic parameters were calculated. The catalytic properties of phosphates Ca0.5(1 + x )Cr x Ti2 ? x (PO4)3 in methanol conversion were studied. 相似文献
8.
Albina I. Orlova Victoria S. Kurazhkovskaya Miguel A. Salvadó Sergei A. Khainakov 《Journal of solid state chemistry》2003,173(2):314-318
A potassium iron zirconium phosphate, K2FeZrP3O12, was synthesized by thermal treatment of a material obtained by the sol-gel method, mixing two aqueous solutions, the first containing KCl, FeCl3 and ZrOCl2, and the second, H3PO4. The crystal structure was refined using powder X-ray diffraction data. The unit cell is cubic, a=10.0554(3) Å, space group P213. This compound is the first iron zirconium phosphate described with a langbeinite-type structure. 相似文献
9.
Kazantsev G. N. Orlova A. I. Zharinova M. V. Samoilov S. G. Pet'kov V. I. Kurazhkovskaya V. S. 《Russian Journal of Applied Chemistry》2004,77(3):369-375
A series of framework phosphates with varied ratio of cations Na5-2x
B
x
IIZr(PO4)3, BII = Mg, Ca, Sr, Ba (0 x 2) and Na5-3x
Fe
x
Zr(PO4)3 (0 x 1.33) were synthesized and studied under heating. The coefficients of thermal expansion along crystal axes
a
and
c
were calculated, and their dependences on the cationic composition (nature and concentration) and on the occupancy of out-of-framework structural positions were established. 相似文献
10.
V. I. Pet’kov I. A. Shchelokov E. A. Asabina V. S. Kurazhkovskaya D. A. Rusakov K. V. Pokholok B. I. Lazoryak 《Russian Journal of Inorganic Chemistry》2006,51(12):1855-1863
New complex phosphates of titanium, iron, and alkaline-earth metals have been synthesized. X-ray powder diffraction, differential thermal analysis (DTA), and IR spectroscopy are used to study phase formation in the series of M0.5(1+x)FexTi2?x (PO4)3 (M = Mg, Ca, Sr, Ba) phosphates. Individual compounds and solid solutions are found to crystallize in the NaZr2(PO4)3 and K2Mg2(SO4)3 structure types. Their crystal parameters are calculated. CaFeTi(PO4)3 is studied using Mössbauer spectroscopy. Its structure is refined by the Rietveld method: space group $R\bar 3$ c, Z = 6, a = 8.5172(1), Å, c = 21.7739(4) Å, V = 1367.91(4) Å3. 相似文献