共查询到20条相似文献,搜索用时 46 毫秒
1.
M. Meot-Meyer G. Venturini B. MaLaman J. Steinmetz B. Roques 《Materials Research Bulletin》1984,19(9):1181-1186
New ternary stannides are reported : RE2Rh3Sn5 (RE = Y, Gd, Tb, Dy, Ho). Y2Rh3Sn5 has been studied by single - crystal X-ray diffraction analysis. Its structure is of a new type with space group Cmc21 and Z = 4 : a = 4,387(2), b = 26,212(4), , Dx = 8,71 Mgm?3, μ(AgKα) = 17 mm?1, F(000) = 1851, R = 0,045 for 478 independant reflexions (Rw = 0,046). This structure is characterized by a tridimensionnal lattice of RhSn covalent bonds with two very different sites for yttrium. Y2Rh3Sn5 is diamagnetic and semimetallic according to its electrical properties. 相似文献
2.
New ternary stannides are reported: RE1+xRh2Sn4?x, 0 ? x ? 0,5 (RE = La ? Sm). NdRh2Sn4 has been characterized by single - crystal X-ray diffraction analysis. Its structure is of a new type with space group Pnma and Z = 4: a = 18,535(3), b = 4,463(1), , Dx = 9,16 g.cm?1, μ(AgKα) = 13,6 mm?1, F(000) = 1300, R = 0,040 for 496 independent reflexions (Rw = 0,047). One of the tin sites can be partly occupied by rare earths atoms. The structure types of NdRh2Sn4 and Y2Rh3Sn5 are closely related. LaRh2Sn4 does not exhibit superconductivity above 1.4 K. 相似文献
3.
The following new oligomeric selenidogermanates (III) have been prepared and structurally characterized: Na6Ge2Se6: monoclinic, space group (No. 14) a = 836.7(5) pm, b = 1192.4(8) pm, c = 815.8(5) pmβ = 118.63(15)°.The compound is isotypic to K6Sn2Te6, essential structure elements are [Ge2Se6]6? anions.Na8Ge4Se10: triclinic, space group P1? (No. 2) a = 707.4(5) pm, b = 809.8(5) pm, c = 1065.7(6) pmα = 73.44(15)°, β = 70.84(15)°, ?= 81.73(15)°Two Ge2Se6 octahedra are connected by a common edge forming a six-membered cyclic [(GeSe2)4Se2]8? anion. 相似文献
4.
The structural properties of a new ternary germanide of manganese and palladium Pd~12Mn~4Ge8 have been investigated. The crystal structure has been determined by single-crystal X-ray diffraction analysis : R = 0.084 for 1027 independent reflexions. The structure is of a new type with one formula unit in an orthorhombic unit cell of space group Pnma, having the dimensions : , , . It is closely related to the Fe2P, Co2P and Fe2As type structures. Pd~12Mn~4Ge8 is ferromagnetic. 相似文献
5.
The crystal structure of Mn0, 4Er4, 6S7 (, , , γ = 105,45°, space group B2/m, Z = 2) has been refined by a least square method to a final R = 0,045, with 1431 independant reflections. The octahedral positions are occupied either by Er and Mn atoms or by Er atoms only and the prismatic sites by Er atoms. 相似文献
6.
M. Meyer G. Venturini B. Malaman J. Steinmetz B. Roques 《Materials Research Bulletin》1983,18(12):1529-1535
LuMnGe2 has been studied by single - crystal X-ray diffraction analysis. The structure is of a new type with space group Cmmm and Z = 12: a = 5.466(2), b = 18.519(7), , Dx = 9.03 Mg m?3, μ(AgKα) = 31 mm?1, F(000) = 1919, R = 0.030 for 593 independant reflexions (Rw = 0.034). The LuMnGe2 structure type had been predicted and completes a large structural family TT′Si(Ge)2 where T = Nb, Ti, Zr, Hf, Sc, Lu and T′ = Cr, Mn, Re, Fe, Co, where ScMnGe2 is another new member, isostructural with TiMn(Fe)Si2 相似文献
7.
The ionic conductivity of polycrystalline samples of three lithium germanates: Li4GeO4, Li2GeO3, and Li2Ge7O15, has been determined using a c techniques and complex plane analysis. Conductivities at 400°C are 8.7 × 10?5, 1.5 × 10?5, and respectively. The conductivity of Li4GeO4 rises appreciably in the range 700–750°C. 相似文献
8.
Abdelhamid Boudjada 《Materials Research Bulletin》1980,15(8):1083-1090
Monophosphate hydrogen copper monohydrate : CuHPO4,H2O is monoclinic, space group . The unit cell parameters are : a = 8.63(6), b = 6.35(3), , β = 94.14(6°) and Z = 4. The crystal structure has been determined with 1249 independent reflexions and refined to a final R value of 2.9%. The crystal is built up of PO4 tetrahedron and CuO6 octahedron deformed by Jahn-Teller effect which are linked to form a three dimensional network.Based on the inter-ionic distances between CuII and O2? in the recently determined structures of monoarsenates or phosphates, we give a value for the effective ionic radius of copper II. 相似文献
9.
The cell is orthorhombic, a = 8.051(3); b = 8.169(3); ; Z = 8; space groupe Pnam, dcalc = 7.2; dobs = 7.1; μ = 897 cm?1. R = 0.065 for 1636 reflections.The anion Sn2Se4?3 is formed by two SnSe4 tetrahedra, which have a common edge. Two kinds of thallium atoms are observed, with different coordinations. 相似文献
10.
The pressure-temperature phase diagram of Sm2Ge2O7 was determined up to 80 kbar and 1400°C. In this pressure-temperature range only two phases were found. The B″ triclinic phase synthetised at atmospheric pressure is stable up to 40 kbar and at higher pressures appears the H phase which is a new type of structure in the rare earth digermanate series. The lattice parameters of the H phase were determined on small single crystals which were grown with water as mineralizer. The symmetry of the H phase is hexagonal with a space group P 6/m m m. The cell parameters of H-Sm2Ge2O7 are and . The measured density is 7,01 g/cm3 and therefore the cell contains twenty seven Sm2Ge2O7 units. The calculated density is 7,16 g/cm3. The X-ray diffraction pattern of H-Gd2Ge2O7 previously obtained can be indexed with similar parameters and . 相似文献
11.
The structure of the compound Cu4NiSi2S7 has been determined. It crystallizes in a new, monoclinic distorted sphalerite superlattice with the parameters: , , , β = 98.72°, , Z = 2, space group C2. The analogous compound Cu4NiGe2S7 is isotypic. At a Neél temperature TN = 20.2 K, Cu4NiSi2S7 becomes antiferromagnetic. The magnetic moment of the paramagnetic phase is 2.6μB. 相似文献
12.
New quaternary oxides are reported : M2Ga2Fe2O9 (M = In,Sc). In2Ga2Fe2O9 has been studied by single-crystal X-ray diffraction analysis. Its structure is a new type with space group Pba2 and , b = 7.2176(2), , Dx = 6.05 g.cm?3, μ(AgKα) = 9mm?1, F(000) = 757.1, R = 0.037 for 420 independant reflexions (Rw = 0.037). The indium are heptahedrally coordinated by seven oxygen atoms and the iron and gallium atoms by five oxygen atoms at the apices of a trigonal bipyramid. 相似文献
13.
Geneviève Vetter Francine Queyroux Jean-Claude Gilles 《Materials Research Bulletin》1978,13(3):211-216
Our crystallochemistry investigation of the Bi2O3 - SnO2 binary in the range of compositions between 60 and 75 SnO2 moles percent, brings new evidence of the compound Bi2Sn2O7. It has a tetragonal structure (, ), related to the pyrochlore structure.From this study arises a new problem about the influence of Bi3+ ion on the doubling of the crystalline parameters. 相似文献
14.
A series of isotypic silicates of composition RE2M[SiO4]2 (OH) with RE = La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, and M = Al3+, Fe3+ has been synthesized under hydrothermal conditions. Lattice constants of two members as determined from single crystal X-ray diffraction data are: La2Al[SiO4]2 (OH) (La2Fe[SiO4]2 (OH)) , , , gb = 112.4 (112.5°), , Z=4. 相似文献
15.
(CH3NH3)2CdBr4 and Cs2CdBr4 are two compounds with a tetrahedral CdBr4-coordination. Their room temperature structures are determined. (CH3NH3)2CdBr4: monoclinic, , , , , β = 96.194(11) °, z = 4. Cs2CdBr4: orthorhombic, Pnma, , , , z = 4. 相似文献
16.
M.T. Averbuch-Pouchot 《Materials Research Bulletin》1981,16(4):407-411
NH4HSO4·NH4H2PO4 is monoclinic with Z = 2 and the following unit cell dimensions : a = 7.723(5), b = 7.540(5), , β = 101.32(5)°. Crystal structure of this salt has been solved with a final R value 0.028. As in the corresponding potassium salt PO4 and SO4 tetrahedra are randomly distributed.A complete hydrogen bonding pattern is given. 相似文献
17.
Un nouveau sulfure de molybdène : Mo3S4, isostructural de Mo3Se4, a été préparé. Sa maille cristallographique est rhomboédrique : a = 6, re A ; α = 91°34 ; Z = 2 ; groupe spatial R3?. Sa structure est caractérisée par un motif Mo6S8 constitué d'un cluster octaédrique Mo6 ( et 2, 86 Å) inscrit dans un cube déformé de soufre. 相似文献
18.
Mg2PN3 has been prepared by reaction in solid state between Mg3N2 and P3N5. It crystallizes with orthorhombic symmetry, space group Pna21, with unit cell parameters a = 9.759 (5), b = 5.635 (3), . Its structure is related to the wurtzite type with Mg and P atoms ordered. It is the first example of PN4 tetrahedra in a normal tetrahedral structure. 相似文献
19.
The prompt recrystallization of the tetragonal phyllophosphate HUP, (UO2)[HPO4] · 4H2O, when rinsed with distilled water at ambient temperature, has been studied by TEM, SEM and SAD. In course of the rinsing process, to remove excess phosphorous acid, HUP underwent an orthorhombic phase change, which produced two orthorhombic phases O1 and O2. O1 has , , and 001 absent for l odd. O2 has , and no systematic absent reflections. O1 and O2 are metastable and by spinodal decomposition modulate into monoclinic phases through a string of intermediate and disordered phases with the β-angle increasing from 90.0° (orthorhombic phases) to 91.3(3)°, 95(2)° and 97.7(2)° for M2.2, M2.1, and M1.1 respectively, where M1.1 is the monoclinic derivative (, , β = 97.7(3)°) of O1 and M2.1 (, , β = 95(2)°) together with M2.2 (, , β = 91.3(3)°) are the derivatives of O2. The crystallographic b axis could not be determined. All the abovementioned phases exhibit a striking epitaxial relationship which presumably gives the clue to the fact that these phase findings are at variance with X-ray findings given in literature. It is suggested that the phases are isomeric polymorphs of HUP. 相似文献
20.
Copper(II)metagermanate, CuGeO3, decomposes at high pressure to rutile-type GeO2 and Cu2GeO4. Very small single crystals of Cu2GeO4 can be obtained by direct high pressure synthesis from CuOGeO2 mixtures. The compound has a distorted spinel structure (Hausmannite structure, space group ) with , , Z = 4. 相似文献