X‐ray powder diffraction study of the semiconducting alloy Cu2Cd0.5Mn0.5GeSe4

The structure of the semiconducting alloy Cu₂Cd_0.5Mn_0.5GeSe₄ was refined from an X‐ray powder diffraction pattern using the Rietveld method. The present alloy crystallizes in the wurtz‐stannite structure, space group Pmn2₁ (N^o 31), and unit cell parameters values of a = 8.0253(2) Å, b = 6.8591(2) Å, c = 6.5734(2) Å and V = 361.84(2) ų. The structure exhibits a three‐dimensional arrangement of slightly distorted CuSe₄, Cd(Mn)Se₄ and GeSe₄ tetrahedras connected by corners. © 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim     

Crystal structure refinement of CuxAg1‐xInTe2 bulk material determined from X‐ray powder diffraction data using the Rietveld method

The influence of the Cu‐content in the quaternary compounds Cu_xAg_1‐xInTe₂ (0 ≤ x ≤1) on the structural properties of the bulk material was discussed. Bulk ingot materials of Cu_xAg_1‐xInTe₂ solid solutions (x = 0.0, 0.25, 0.50, 0.75 and 1.0) have been synthesized by fusion of the constituent elements in the stoichiometric ratios in vacuum‐sealed silica tubes. The materials compositions were confirmed by using energy dispersive analysis of X‐rays (EDAX). X‐ray powder diffraction measurements were performed for all the prepared samples at 300 K in step scanning mode. The analysis of X‐ray data has indicated that the crystal structure of the prepared materials with different compositions is single‐phase polycrystalline materials corresponding to the tetragonal chalcopyrite structure with space group I 2d. The crystal structural parameters were refined by Rietveld method using the Full Prof program. The refined lattice constants (a and c), anion positional parameter, u, and the determined bond distances and angles were found to vary with composition, x, attaining zero tetragonal distortion at x ≈ 0.75, which corresponds to an ideal tetragonal unit cell. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

X‐ray powder diffraction structural characterization of Ba1‐xEuxTiO3 ternary oxides

The single‐phase Ba_1‐xEu_xTiO₃ (0.1≤x≤0.4) samples have been synthesized by solid state reaction under high pressure and ‐temperature. X‐ray powder diffraction data was determined by MS Modeling using Reflex Powder Indexing technique. The Ba_1‐xEu_xTiO₃ series exhibited an interesting orthorhombic‐tetragonal‐cubic structural transformation as Eu composition increases, the distinct change of the X‐ray diffraction peak profile in the vicinity of 45.5º is characteristic of structural transformation. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,spectroscopic studies and ab‐initio structure determination from X‐ray powder diffraction of bis‐(N‐3‐acetophenylsalicylaldiminato)copper(II)

The synthesis, spectroscopic studies and crystal structure determination from X‐ray powder diffraction have been carried out for bis‐(N‐3‐acetophenylsalicylaldiminato)copper(II). The structure is triclinic, space group P1 with unit cell dimensions a = 11.817(1) Å, b = 12.087(1) Å, c = 9.210(1) Å, α = 102.62(1)°, β = 111.16(1)°, γ = 86.15(1)°, V = 1197.0(2)ų, Z = 2. The structure has been solved by Monte Carlo simulated annealing approach and refined by GSAS package. The final Rp value was 8.68%. The coordination geometry around the copper atom in the complex is intermediate between square‐planar and tetrahedral with two salicylaldimine ligands in trans arrangement. Intermolecular C–H…O hydrogen bonds between molecules related by translation generate infinite chains along [010] direction. The molecular chains are linked via additional C–H…O hydrogen bonds to form a three‐dimensional supramolecular network. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis and X‐ray powder diffraction studies of semiconducting alloys in the system AgCd2‐xZnxGaS4

X‐ray powder technique was used in the investigation of AgCd₂GaS_4–'AgZn₂GaS₄' section to determine the region of AgCd₂GaS₄‐based solubility. It was established that the solid solution forms up to 75 mol.% 'AgZn₂GaS₄'. The refinement of AgCd_0.5Zn_1.5GaS₄ structure was performed. This alloy crystallizes in orthorhombic structure (space group Pmn2₁ ) with unit cell parameters a =0.78772(2), b =0.67221(2), c =0.64019(2) nm, V =0.33899(3) nm³. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Thermal analysis,powder diffraction and spectroscopic investigation of the solid phases of 1‐chloro‐2,2‐dimethylpropane

By the substitution of one methyl group in Neopentane C(CH₃)₄ with a methylchlorid group the globular sphere is expanded in 1‐chloro‐2,2‐dimethylpropane (CH₃)₃C(CH₂Cl). With the aid of DSC measurements, X‐ray powder diffraction, ¹H NMR and ³⁵Cl NQR measurements two orientationally disordered (plastic) phases were established. The low temperature structure was solved and a structural model of phase II is proposed. A mechanism to describe the reorientation in the different phases is given as well as a connectivity scheme between the phases is discussed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Ba2.2Ca0.8Mg4F14, a new “solid solution stabilized” matrix for an intense blue phosphor

Barium calcium magnesium fluoride (Ba₂(Ba_xCa_1‐x)Mg₄F₁₄, x=0.19‐0.26) has been synthesized at 850 °C from precursors prepared by the solution precipitation method. Single crystals with composition of Ba_2.200(2)Ca_0.800(2)Mg₄F₁₄were obtained after prolonged heating. Lattice parameters from single crystal data are a = 12.4203(8) and c = 7.4365(5) Å [tetragonal, space group P4₂/mnm (No. 136)]. They increase with increasing barium concentration within a given stability window. The structure is built of a network of MgF₆ octahedra forming a pyrochlore related channel system and isolated fluorine ions. Within the channels, heavy alkaline earth ions are located. The wide channel is filled with off‐center positioned barium ions. The channel with a narrow cross section hosts both ions, Ca²⁺and Ba²⁺. The structure is isotypic with Pb₃Nb₄O₁₂F₂ but has a different coordination around Ba/Ca and Pb, respectively. Doped with ∼1% Eu(II), the compound shows intense blue luminescence under UV activation. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Thermal expansion and structural properties of (CuAlTe2)1–x(CuAlSe2)x solid solutions

Investigations of the thermal expansion of (CuAlTe₂)_1–x(CuAlSe₂)_x solid solutions in the temperature range from 100 to 800 K have been carried out for the first time. It has been demonstrated that the thermal expansion coefficient α_L grows considerably in the temperature range from 100 to 300 K, whereas the temperature dependence above 300 K is rather weak. The isotherms of composition dependence of the thermal expansion coefficient α_L for 100, 293, 500 and 800 K were constructed, and it was found that linear relations could express them. The Debye temperatures θ_D , the average mean‐square dynamic displacements , the average root‐mean‐square amplitudes of thermal vibration RMS , the anion position parameter u using S. C. Abrahams & J. L. Bernstein (u_AB ) and J. E. Jaffe & A. Zunger (u_JZ ) models were calculated. The composition dependence of microhardness H using the phenomenological theory was also calculated, and it was discovered that this dependence has a non‐linear character with a maximum of 383 kg/mm² at x=0.67. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

X‐ray diffraction analysis of powder and thin film of (Gd1‐x Yx)2O3 prepared by sol‐gel process

The mixed oxide (Gd_1‐xY_x)₂O₃ (0.0 ≤ x ≤ 1.0) were synthesized, as powder and thin film, by a sol‐gel process. X‐ray diffraction data were collected and crystal structure and microstructure analysis were performed using Rietveld refinement method. All samples were found to have the same crystal system and formed solid solutions over the whole range of x. The cationic distribution, Gd³⁺ and Y³⁺, over the two non‐equivalent sites 8b and 24d of the space group Ia3 is found to be random for all values of (x). The lattice parameter is found to vary linearly with the composition (x). Replacing Gd³⁺ and Y³⁺ by each other introduces a systemic decrease in the x‐coordinate of cation position (24d) and slight changes in the oxygen coordinates. Crystallite size and microstrain analysis is performed along different crystallographic directions and anisotropic changes are found with the composition parameter (x). The average crystallite size ranges from 75 to 149 nm and the r.m.s strain from 0.027 to 0.068 x10^‐2. Textured Gd_1.841Y_0.159O₃ (400) buffer layers, with a high degree of alignment in both out‐plane and in‐plan, are successfully grown on cube textured Ni (001) tape substrates by sol–gel dip coating process. The resulting buffer layers are crack‐free, pinhole‐free, dense and smooth. YbBa₂Cu₃O_7‐x (YbBCO) thin film could be (00l) epitaxially grown on the obtained buffer layer using sol–gel dipping technique. (© 2007 WILEY ‐VCH Verlag GmbH & Co. KGaA, Weinheim)