European Journal of Solid State and Inorganic Chemistry最新文献

Preparation, characterization by X-ray diffraction, IR absorption, DTATG analysis, and ab-initio crystal structure determination are reported for anhydrous lithium cyclohexaphosphate Li₆P₆O₁₈. It crystallizes in a monoclinic cell (space group P2₁/n N^o14, Z=2) with a = 7.9911(3)Å, b = 17.0319(6)Å, c = 5.3208(2)Å and β = 99.433(1)°. X-ray powder diffraction data were fitted by Rietveld method leading to R_Bragg = 0.034. The crystal structure of Li₆P₆O₁₈ is built up from P₆O₁₈ ring anions, with 1 internal symmetry. Six lithium coordination polyhedra (two pseudo square pyramids and four tetrahedra) share common edges and corners as to form Li₆O₁₆ groups. These cationic groups build up a layer in the (1 0 1¯) plane showing large distorted hexagonal tunnels and interconnect the P₆O₁₈ rings in a three dimensional way.

A calcining at 300°C and sintering process were proposed to obtain a pure perovskite phase Pb(Fe_1/2 Nb_1/2)O₃ from a 4PbO/Nb₂O₅/Fe₂O₃ mixture, which is calcined at 300°C for several days and sintered at various temperatures for 2h; the resultant powder was air quenched. The X-ray powder diffraction pattern of the sintered sample is carefully analyzed to identify intermediate phases. The effects of calcining at 300°C and sintering on obtaining PFN are based on the deformation of Pb₅Fe₄Nb₄O₂₁. A reaction mechanism for the calcining cycle of Pb(Fe_1/2 Nb_1/2)O₃ is proposed.

T6he study of the subsolidus phase equilibrium in Cu-Sb-O system was started using samples with compositions laying, at room temperature, in the CuO-Sb₂O₃ subsystem. Isothermal and non-isothermal experiments were performed to analyze the system in the 500–1000°C range. At high temperatures (over 500°C) the system transforms in a quaternary one: CuO-Cu₂O-Sb₂O₃-Sb₂O₅ as Sb₂O₃ undergoes oxidation to Sb₂O₄ and Sb₂O₅ and Cu₂O₃ reduces to Cu₂O. The formation of the CuSb₂O₆ and Cu₄SbO_4.5 binary compounds is reported. The calculations of mass variation and atomic composition modifications lead to a quaternary oxide representation of the subsolidus phase equilibrium.

The structure of Li₇N₂I has been redetermined from neutron diffraction data using the high resolution powder diffractometer (HRPD) at the spallation source ISIS, UK. The title compound crystallizes in the space group F4¯3m (No.216), a=1038.797(1) pm with eight formula units per unit cell. The Li₇N₂I-structure comprises a cationic Li₁₃N₄^staggered+ framework which is built of monocapped octahedra. While all Li atoms at the vertices are shared between two neighbouring units, the capping metal atom is shared by four octahedra. The Li₁₃N₄^staggered+ network is closely related to the B₂X₆ octahedral framework observed in the pyrochlore structure. Large voids in the structure are occupied by iodide and a Li⁺T ion pair. There is evidence that the nonsphericity of the Li⁺I⁻ dipole induces a complicated Lidisorder in the Li-N framework.

Spray pyrolysis process has been used to deposit highly transparent and conducting films of tin doped indium oxide onto glass substrates. The electrical, optical and structural properties have been investigated as a function of various deposition parameters namely dopant concentrations, temperature and nature of substrates. X-ray diffraction patterns have shown that deposited films are polycrystalline without second phases and have preferred orientation [400]. Indium tin oxide layers with small resistivity value around 7.10⁻⁵Ω.cm and transmission coefficient in the visible and near IR range of about 85–90 % have been easily obtained.

The structure of monoaquabis(pyridine)bis(saccharinato)copper(II), [Cu(H₂O)(py)₂(sac)₂], has been investigated by X-ray diffraction and infrared spectroscopy. The complex crystallizes in the orthorhombic space group I bat2 with the following unit cell parameters: a = 9.4874(7), b = 21.545(1), c = 13.164(1) Å, V= 2690.8(4) ų, D_c = 1.491 g cm⁻³, Z = 4, R = 0.025, wR = 0.036. The structure consists of individual [Cu(H₂O)(py)₂(sac)₂] molecules. The copper atom is bonded to two pyridine and two saccharinato nitrogen atoms as well as to the water oxygen atom forming a distorted square pyramid. The copper atom lying on a twofold rotation axis is 0.2209(7) Å above the basis square plane formed by the four nitrogen atoms. The bond distances in the coordination polyhedron are: Cu-N11 2.032(2) Å, Cu-N21 2.040(2) Å, Cu-OW1 2.177(2) Å. The N-Cu-N angles amount 88.67(8)° and 89.97(8)° as well as 167.36(9) and 167.69(8)°, while the values of the OW1-Cu-N angles are 96.16(6)° and 96.32(6)°. The FT infrared spectral features in the region of the OH, OD, CO and SO₂ stretching vibrations are discussed and correlated with the data obtained by X-ray diffraction.

A brief overview on two novel spray pyrolysis techniques developed recently in our laboratory, i.e. Electrostatic Spray Deposition (ESD) and Flame-Assisted Ultrasonic Spray Pyrolysis (FAUSP), is presented in this paper. Alcoholic solutions of metal salts or alkoxides are used as precursor solutions. Both techniques have been successfully applied to synthesize electroceramic materials including semiconductor TiO₂, ionic conductor ZrO₂, and mixed electronic-ionic conductor LiMn₂O₄. ESD is usually used for the fabrication of thin films with various morphologies, while FAUSP is used for the production of fine powders.

The sequence of phase transitions in the system La₂O₃-MO(MCO₃)Mn₂O₃, (M=Ca, Sr, Ba, Cd) and the span range of La_1−xM_xMnO_3±δ solid solutions formed were studied. It is demonstrated that interaction begins at 650°C due to formation of divalent metal manganites. Just simultaneously as a result of oxidation-reduction processes and structural transformations the synthesis of small quantities of solid solutions takes place, which is kinetically favoured in the case of smaller divalent metal cations. The chemical transformation finishes at 1200°C. The values of x at all systems are near 0,35. The absence of CdMnO₃ composition in the system CdO-MnO is proved.

The title compound has been prepared by hydrothermal synthesis and its crystal structure was determined by single crystal X-ray diffraction: space group P2₁/m, a = 4.8890(2), b = 14.3857(5), c = 7.9017(3) Å, β = 90.134(4)°, wR₂ = 0.123, R = 0.045. Cu²⁺ has two different coordination polyhedra: an elongated square pyramidal [CuFO₄] and square planar [CuO₄] coordination in a 2:1 ratio. Edge-sharing double-pyramids and [CuO₄] squares form zig-zag chains interconnected by [ZnO₄] and [PO₄] tetrahedra to form an open anionic framework structure whose channels are occupied by the K⁺ ions.

The structure of CrVMoO₇ has been refined from high-resolution X-ray powder diffraction data. The unit cell is triclinic (space group P1¯) with a=5.531(1)Å, b=6.585(1)Å, c=7.864(1)Å, α=96.143(6)°, β=89.847(6)° and γ=101.942(6)°. A two-step refinement yields R_p=8.7% in the first step (pattern matching) and in the second step (structure refinement)as well. The crystal structure of the compound is isotypic to FeVMoO₇. The distortion of the coordination polyhedra has been discussed within the framework of the bond valence concept and effective coordination numbers.