Etude cristallographique du systeme FeSSc2S3 preparations et structures de FeSc2S4 et Fe0.85Sc2.10S4

The crystal structures of FeSc₂S₄ and Fe_0.85Sc_2.10S₄ have been determined by three dimensional X-ray diffraction. The cubic cells, space group Fd3m, have lattice constants $\text{a}\text{= 10,501}\text{A}\text{?}$ for FeSc₂S₄ and $\text{a}\text{= 10,444}\text{A}\text{?}$ for Fe_0.85Sc_2.10S₄. Iron is divalent and scandium trivalent. FeSc₂S₄ is a direct spinel structure, Fe_0.85Sc_2.10S₄ is near a spinel structure. Only 0,5 iron atom is on every 8a position; 0,175 Fe and 1,05 Sc lie on octahedral 16d and 16c site.     

Contribution a l'etude du polymorphisme de Ga2S3: Structure cristalline de Mn0,23Ga1,85S3

The Mn_0.23Ga_1.85S₃ phase belongs to the solid solution $\text{ф}{}_0$, stable at low temperature in the Ga₂S₃MnS system. It is hexagonal superstructure of the wurtzite, with the Ga₂S₃α′ type ($\text{a}\text{= 6.397}\text{A}\text{?}$; $\text{c}\text{= 18.027}\text{A}\text{?}$Z = 6; space groupe P6₁ or P6₅). Its crystal structure has been refined by the least squares method to a final R = 0.06 with 323 independant reflections. This structure is closely related to Ga₂S₃ α described by Hahn and Frank, and differs only by the partial occupation of the vacant metal site of Ga₂S₃ by Mn atoms in statistical disorder.     

Une structure derivee de celle du spinelle la structure de Fe0.76 Yb2.16 S4

Single crystals of so-called “FeYb₂S₄ spinel” were prepared and their crystal structure was solved. The cubic cell, space group Fd3m, has a lattice constant $\text{a}\text{= 10.69}\text{A}\text{?}$. From X-rays determinations, its content is (Fe_0.76 Yb_2.16 S₄) × 8. Iron is divalent and ytterbium is trivalent. Ytterbium is in two series of octahedral sites, which are partially filled : 0.96 Yb and 0.04 ? on every 16d position, 0.12 Yb and 0.88 ? on every 16c position. Only 0.76 iron atom is in every 8a position of the spinel.     

Structure cristalline de Mn0, 4Er4, 6S7

The crystal structure of Mn₀, ₄Er₄, ₆S₇ ($\text{a}\text{= 12,573 (4)}\text{A}\text{?}$, $\text{b}\text{= 11,390 (4)}\text{A}\text{?}$, $\text{c}\text{= 3,777 (4)}\text{A}\text{?}$, 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.     

Structure cristalline du polytype FeGa2S4α 1T

The crystal structure of the low temperature form of α-FeGa₂S₄ 1T (with $\text{a}\text{= 3,654(2)}\text{A}\text{?}$; $\text{c}\text{= 12,056(7)}\text{A}\text{?}$; Z = 1, space groupe P3̄m1) has been refined by a least squares method to a final R = 0.051 with 180 independant reflections. The sulfur stacking sequence in this polytype is…BCBC…Fe atoms occupy the octahedral voids and Ga atoms the tetrahedral voids.     

Synthesis of mercury bismuth sulfide HgBi2S4

The compound HgBi₂S₄ was found to be the only phase present, other than the end members, in mixtures of HgS and Bi₂S₃. The compound is apparently a new structure type with monoclinic symmetry, space group C2, Cm or C2/m $\text{a}\text{=14.179,}\text{b}\text{=4.0555,}\text{c}\text{=13.986}\text{A}\text{?}\text{, β=118°13.8′}$.     

Un compose a structure feuilietee (LaO)4Ag1,5Ga1,5S5

The compound (LaO)₄Ag_{1 · 5}Ga_{1 · 5}S₅ belongs to the quasi-binary La₂O₂SAgGaS₂ system. It undergoes a peritectic decomposition at 1040°C and a order-disorder transition at 750°C. The high temperature variety is tetragonal, with $\text{a}{}_0\text{= 4.18}\text{A}\text{?}$; $\text{c}{}_0\text{= 18.74}\text{A}\text{?}$; Z = 1; space group 1422; it has the same structural type as (CeO)₄Ga₂S₅. The low temperature variety is an orthorhombic superstructure of the preceding one. with a = 17.58 (3 a₀√2); b = 5.90 (a₀√2) and $\text{c}\text{= 18.66}\text{A}\text{?}$ (c₀). The electrical conductivity is mainly of ionic nature. The e.m.f. measurements of a cell Ag/(LaO)₄Ag_{1 · 5}Ga_{1 · 5}S₅/S.C./Pt support this conclusion.     

High pressure synthesis of Cu2GeO4 with hausmannite structure

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 CuOGeO₂ mixtures. The compound has a distorted spinel structure (Hausmannite structure, space group $\text{I}\text{4}{}_1\text{amd}$) with $\text{a}\text{= 5.593}\text{A}\text{?}$, $\text{c}\text{= 9.396}\text{A}\text{?}$, Z = 4.     

Comments on the system Ag2SIn2S3

The high temperature polymorph of AgInS₂ has been found to be orthorhombic with $\text{a}\text{=7.001}$, $\text{b}\text{=8.278}$, $\text{c}\text{=6.698}\text{A}\text{?}$, space group probably Pna2₁ with a distorted wurtzite structure. The phase transition temperature was found to be 620 ± 10°C and the melting point 880 ± 10°C. A new cubic spinel type phase was found at the composition AgIn₅S₈ with $\text{a}\text{=10.827}\text{A}\text{?}$.     

Crystal structure and magnetic properties of Cu4NiSi2S7

The structure of the compound Cu₄NiSi₂S₇ has been determined. It crystallizes in a new, monoclinic distorted sphalerite superlattice with the parameters: $\text{a}\text{= 11.551}\text{A}\text{?}$, $\text{b}\text{= 5.313}\text{A}\text{?}$, $\text{c}\text{= 8.165}\text{A}\text{?}$, β = 98.72°, $\text{V}\text{= 495.2}\text{A}\text{?}{}^3$, Z = 2, space group C2. The analogous compound Cu₄NiGe₂S₇ is isotypic. At a Neél temperature T_N = 20.2 K, Cu₄NiSi₂S₇ becomes antiferromagnetic. The magnetic moment of the paramagnetic phase is 2.6μ_B.     

Preparation of ferrimagnetic SnCr2S4

SnCr₂S₄ has been prepared for the first time. It is hexagonal ($\text{a}\text{= 21.325}\text{A}\text{?}$ and $\text{c}\text{= 3.4690}\text{A}\text{?}$) and ferrimagnetic (T_C = 100 K).     

Macle et structure cristalline de Mn0,75Ga2,17S4

Twins of $\text{Mn}{}_{\mathrm{<mtext>1?</mtext><mtext>x</mtext>}}\text{Ga}{}_{\mathrm{<mtext>2+</mtext><mtext>2</mtext><mtext>3</mtext><mtext>x</mtext>}}\text{S}{}_4$ were used for crystal structure determination. Twinning is explained by a reticular pseudomerihedry. Axis, plane and obliquity of the twin have been determined. Cell dimensions are: $\text{a = b}\text{= 5.456(2)}\text{A}\text{?}$; $\text{c}\text{= 10.220(4)}\text{A}\text{?}$; α = β = γ = 90°; space group 14; Z = 2. The final R value is 0.059. The material is isostructural with CdGa₂S₄.     

Die strukturen des MgAl2S4 und Mg0.830In2.113S4

MgAl₂S₄ crystallizes in the orthorhombic system, space group Pnma (No 62) with the lattice constants: a=1251.1 ± 0.6 pm, b =722.0 ± 0.4 pm, c=592.1 ± 0.4 pm The compound is isotypic to BeAl₂O₄.Mg_0.830In_2.113S₄ forms the spinel structure, space group Fd3m (No 227) with a=1071.9 ± 0.6 pm.     

Phase investigations in the system PbSIn2S3 and the crystal structures of PbIn2S4 and Pb6In10S21

The system PbS-In₂S₃ was examined by differential thermal analysis (DTA), chemical vapour transport (CVT), and X-ray diffraction. Five new phases of compositions closely related to the 1:1 ratio were found and prepared as needle-shaped single-crystals; their crystal data are reported. The structures of PbIn₂S₄ (orthorhombic, Pnma, a=11.688(1), b=3.8528(1), $\text{c}\text{=13.763(1)}\text{A}\text{?}$, Z=4) and Pb₆In₁₀S₂₁ (monoclinic, C2/m, a=27.629(3), b=3.8630(5), $\text{c}\text{=15.705(2)}\text{A}\text{?}$, β=95.9°, Z=2 were solved from 808 resp. 3554 independent reflexions and refined to R=0.116 resp. 0.068. In both structures the In-S coordination polyhedra are distorted octahedra, the Pb-S polyhedra are distorted bicapped trigonal prisms.     

Preparation,properties and crystal structure of TlV5S8

A new sulfide of vanadium and thallium TlV₅S₈ has been prepared. It has monoclinic symmetry with space group C2 and cell dimensions: $\text{a}\text{= 17.465}\text{A}\text{?}$, $\text{b}\text{= 3.301}\text{A}\text{?}$, $\text{c}\text{= 8.519}\text{A}\text{?}$ and β = 103.94°. The structure can be described as a 3D framework made up of infinite layers and double chains which consist of VS₆ octahedra sharing faces and edges. Large rectangular tunnels host the thallium atoms. The compound shows metallic behavior.     

Etude structurale des phases Sc5,5Nb1,5O12 et Sc5,5Ta1,5O12. Ordre des cations dans les composes (A,B)7O12 de type Y6UO12

New phases Sc_5,5Nb_1,5O₁₂ and Sc_5,5Ta_1,5O₁₂ were prepared. Their structure is rhombohedral (space group R3, Z = 1) ($\text{a}\text{= 6,080}\text{A}\text{?}\text{α = 99°16}$ (niobate), $\text{a}\text{= 6,084}\text{A}\text{?}\text{α = 99°18}$ (tantalate). Many (A,B)₇O₁₂ ternary oxides have the same fluorite-related structure, the distortion from the cubic lattice depending upon ordering of cations on non-equivalent atomic positions. A sensitive influence of the degree of ordering is observed in the vibrational spectra of those phases.     

Preparation,properties and crystal structure of TlxV6S8

A new sulfide of vanadium and thallium Tl_xV₆S₈ (x = 0.52±0.2) has been prepared. Its unit cell has hexagonal symmetry, space group P₆₃ and dimensions: $\text{a}\text{= 9.187(7)}\text{A}\text{?}$, $\text{c}\text{= 3.298(4)}\text{A}\text{?}$, z = 1. The structure is characterize by infinite triple rutile chains along the $\text{c}$ axis containing short V-V (2.860 Å) distances. The compound shows metallic behavior.     

Un nouveau sulfure de molybdene : Mo3S4 preparation,proprietes et structure cristalline

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 ($\text{Mo}\text{}\text{Mo}\text{= 2, 69}\text{A}\text{?}$ et 2, 86 Å) inscrit dans un cube déformé de soufre.     

Etude d'un nouveau germaniure ternaire : Pd∼12Mn∼4Ge8, de structure apparentee aux types Fe2P,Co2P ET Fe2As

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 : $\text{a}\text{= 6.910 (1)}\text{A}\text{?}$, $\text{b}\text{= 3.146 (1)}\text{A}\text{?}$, $\text{c}\text{= 16.504 (4)}\text{A}\text{?}$. It is closely related to the Fe₂P, Co₂P and Fe₂As type structures. Pd_～12Mn_～4Ge₈ is ferromagnetic.     

The preparation,crystal structures and properties of the potassium vanadium sulfides KXV5S8 (0.5≦x≦0.7)

The crystal structures of the potassium vanadium sulphides K_0.7V₅S₈ and K_0.5V₅S₈ (=KV₁₀S₁₆) have been determined. K_0.7V₅S₈ has a C-centered monoclinic unit cell of dimensions $\text{a}\text{=17.499(3)}\text{A}\text{?}$, $\text{b}\text{=3.2986(6)}\text{A}\text{?}$, $\text{c}\text{=8.489(1)}\text{A}\text{?}$, ß=103.98(1)°, spacegroup C2/m; isomorphous with TIV₅S₈; K_0.5V₅S₈ has essentially the same structure, but due to ordering of the K atoms, the monoclinic b-axis is doubled, thus forming a superstructure. The cell parameters are: $\text{a}\text{=17.462(4)}\text{A}\text{?}$, $\text{b}\text{=6.556(2)}\text{A}\text{?}$, $\text{c}\text{=8.4595(9)}\text{A}\text{?}$, ß=103.86(1)°, spacegroup P2. The structures are characterized by a three-dimensional framework of VS₆ octahedra with channels in which the K atoms are situated. Both compounds exhibit metallic behaviour.