Browsing by Author "LII, KH"

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AM3(P2O7)2 (A = ALKALINE-EARTH METALS - M = FE, CO, NI) - DIPHOSPHATES CONTAINING INFINITE CHAINS OF EDGE-SHARING MO6 OCTAHEDRA
(1993-09-29)
LII, KH
;
SHIH, PF
;
CHEN, TM
;
應用化學系
;
Department of Applied Chemistry
Diphosphates of the stoichiometry AM3(P2O7)2 (A = alkaline-earth metals; M = Fe, Co, Ni) have been synthesized and structurally characterized by single-crystal X-ray diffraction. Crystal data: CaNi3(P2O7)2, monoclinic, P2(1)/c, a = 7.330(3) angstrom, b = 7.589(3) angstrom, c = 9.400(3) angstrom, beta = 11 1.90(3)-degrees, V = 485.1(3) angstrom3, Z = 2, and R = 0.026; CaCo3(P2O7)2, as above except a = 7.394(l) angstrom, b = 7.6266(9) angstrom, c = 9.444(2) angstrom, beta = 11 1.73(2)-degrees, V = 494.7(l) angstrom3, and R = 0.035; SrFe3(P2O7)2, as above except a = 7.553(l) angstrom, b = 7.7477(8) angstrom, c = 9.5796(8) angstrom, beta = 112.11(1)-degrees, V = 519.4(l) angstrom3, and R = 0.029. The three compounds are isostructural, consisting of zigzag infinite chains of MO6 octahedra sharing either trans or skew edges. The infinite chains arc connected by P2O7 groups to form a three-dimensional architecture with channels parallel to the b axis. Alkaline-earth metals are located in sites within the channels. The following isostructural compounds have also been prepared: AM3(P2O7)2 (A = Sr, Ba; M = Ni, Co) and BaFe3(P2O7)2. A magnetic susceptibility study on SrFe3(P2O7)2 indicates that the material is paramagnetic with an effective magnetic moment of 5.07 mu(B) per Fe between 300 and 26 K. Below this temperature the magnetic susceptibility increases sharply to a maximum at 6 K and then decreases rapidly. Mossbauer spectra also confirm the presence of Fe(II).
CRYSTAL-STRUCTURE AND MAGNETIC-PROPERTIES OF A VANADIUM(IV) PYROPHOSPHATE - RB2V3P4O17
(1990-04-01)
LII, KH
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WANG, YP
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CHNEG, CY
;
WANG, SL
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KU, HC
HYDROTHERMAL SYNTHESIS AND CRYSTAL-STRUCTURES OF BA2FE3H(PO4)2(P2O7)2 AND BA2V3H(PO4)2(P2O7)2
(1993-10-01)
DVONCOVA, E
;
LII, KH
;
LI, CH
;
CHEN, TM
;
應用化學系
SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF SODIUM VANADYL(IV) ORTHOPHOSPHATE NAVOPO4
(1991)
LII, KH
;
LI, CH
;
CHEN, TM
;
WANG, SL
;
應用化學系
A new sodium vanadyl(IV) orthophosphate NaVOPO4 has been synthesized by solid-state and hydrothermal method and characterized by single-crystal X-ray diffraction and magnetic susceptibility. It crystallizes in the monoclinic space group P2(1)/c with a = 6.524(1), b = 8.455(4), c = 7.119(1), beta = 115.29(1)-degrees, Z = 4, R = 0.027, and is structurally similar to the triclinic analog LiVOPO4. The structure can be described as close-packed infinite chains of trans-corner-sharing VO6 octahedra with the holes around each chain filled with Na and P atoms. These infinite chains have alternating short and long V - O bonds and are similar to those found in beta-VOPO4. The Na atom has six close oxygen neighbors at distances of 2.268 to 2.511 angstrom.