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1.
The single‐phase Ba1‐xEuxTiO3 (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 Ba1‐xEuxTiO3 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) 相似文献
2.
Aditya M. Vora 《Crystal Research and Technology》2007,42(3):286-289
Indium intercalated MoSe2 single crystals i.e. InxMoSe2 (0 ≤ x ≤ 1) are grown by direct vapour transport technique. These crystals are structurally characterized by X‐ray diffraction, by determining their lattice parameters ‘a’ and ‘c’ and X‐ray density. The Hall effect and thermoelectric power measurements shows that InxMoSe2 (0 ≤ x ≤ 1) are p‐type in nature. The direct and indirect band gap measurements are also undertaken on these semiconducting materials. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
3.
The thermal decomposition of freeze‐dried Li‐Mn(II)‐Fe(III)‐formate precursors was investigated by means of DTA, TG and mass spectroscopy. By the thermal treatment of the prefired precursors between 400 and 1000°C, single phase solid solutions LixMn1+xFe2–2xO4 (0 ≤ x ≤ 1) with cubic spinel structure were obtained. To get single phase spinels, special conditions concerning the temperature T and the oxygen partial pressure p(O2) during the synthesis are required. Because of the high reactivity of the freeze‐dried precursors, in comparison with the conventional solid state reaction, the reaction temperature can be lowered by 200°C. The cation distribution and the properties of the Li‐Mn‐ferrites were studied by chemical analysis, X‐ray powder diffraction and magnetization measurements. It was found that for high substitution rates, almost all lithium occupies the tetrahedral coordinated A‐sites of the spinel lattice AB2O4, while at small x‐values, lithium ions are distributed over the tetrahedral and octahedral sites. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
4.
Single crystals of CdGa2(1‐x)Cr2xSe4 compounds for 0 ≤ x ≤ 1 have been grown by using the chemical vapor transport technique in a closed system. The transporting agent was CdCl2 in a proportion of 0.75 mg/cc of capsule. The starting material was previously synthetized. The structural characterization on the crystals were done by powder x‐ray diffraction studies. The results show three different phases for various Cr concentration ranges: spinel structure for x ≥ 0.7, rombohedral for 0.6 ≥ x ≥ 0.5 and tetragonal for 0.4 ≥ x ≥ 0. That is, the chromium dilution in the CdCr2Se4 compound by Ga atoms produces very significant changes in the structural atomic arrangement. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
5.
Substituted barium hexaferrites, BaFe12‐2xZnxTixO19 (0 ≤ x ≤ 2), have been synthesized by thermal decomposition of freeze‐dried acetate precursors. Decomposition and phase formation were investigated by means of thermal analysis, XRD and IR spectroscopy. The initially amorphous decomposed precursor reacts to the substituted hexaferrite via a spinel‐like maghemite (γ‐Fe2O3) and Zn/Ti containing spinel ferrites. The synthesis method allows a decrease of the reaction temperature and time, necessary for producing a single phase hexaferrite. At relative low reaction temperatures, the substitution rate x shows remarkable differences at different iron sublattices. For x ≤ 0,8 this selective substitution results in an increase of magnetization as x grows. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
6.
The mixed oxide (Gd1‐xYx)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 Gd1.841Y0.159O3 (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. YbBa2Cu3O7‐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) 相似文献
7.
Z. K. Heiba M. Bakr Mohamed M. A. Abdelslam L. H. Fuess 《Crystal Research and Technology》2011,46(3):272-276
The mixed rare earth oxide (Dy1‐xErx)2O3 (0.0 ≤ x ≤ 1.0) were synthesized by a sol–gel process. X‐ray and neutron diffraction data were collected and crystal structure and microstructure analyses were performed using Rietveld refinement method. All samples were found to have the same crystal structure and formed solid solutions over the whole range of x. Preferential cationic distribution is found for all samples but with different extent with Dy3+ preferring the 8b among the two non‐equivalent sites 8b and 24d of the space group Ia3. The lattice parameter is found to vary linearly with the composition x and a systematic variation is found in the r.m.s microstrain . Magnetization measurements were done in the temperature range 5‐300 K and a behavior in accordance with Curie‐Weiss law was found. Anomalous concentration dependence is found in magnetic susceptibility which is ascribed to the concentration dependence of effective crystal field combined with the contribution of 4I15/2 and 6H15/2 manifold at elevated temperature. The effective magnetic moments μeff is found to decrease linearly with composition parameter x, except for sample x=0.5 where the magnetization is enhanced. The Curie‐Weiss paramagnetic temperatures indicated antiferromagnetic interaction. These magnetic results are discussed in view of the cationic distribution. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
8.
D.I. Savytskii M. Berkowski L.O. Vasylechko J. Fink‐Finowicki A.O. Matkovskii 《Crystal Research and Technology》2000,35(1):53-63
For La1‐xNdxGaO3 crystals the La‐Nd substitution leads to decrease of spontaneous strains and for composition with x≈0.32 the six possible twin states of orthorhombic phase (m3mFmmm) may be degenerated in three twin states inhered in m3mF4/mmm species when a distorted perovskite pseudocell becomes tetragonal. The {110} and {112} reflection twins and axial twins with compositional planes close to (211) and (21‐1) (S‐walls) were identified in La1‐xNdxGaO3 (x=0.07, 0.12, 0.20) solid solutions crystals. All observed twins are typical for crystals with GdFeO3 type perovskite‐like structure. It has been shown that for x≤0.2 and x≥0.5 orientations of S‐walls weakly depend on La/Nd ratio, whereas in the range of 0.2<x<0.5 they depend strongly on the solid solution composition. The tilt angle between two twin states across twin boundary in La1‐xNdxGaO3 (x<0.6) solid solutions is smaller than that between two twins in pure LaGaO3 or NdGaO3. 相似文献
9.
Copper iron oxides, Cu1‐xFe2+xO4 (0 ≤ x ≤ 0.5), have been synthesized by thermal oxidation of copper ‐ iron mixtures. In this process, the phase formation and the phase stability were investigated as function of the temperature (800°C – 1200°C) and the oxygen partial pressure (1.013 x 101 – 1.013 x 105 Pa). The phase formation starts with the reaction of the metallic components to simple oxides (Fe3O4, Fe2O3, CuO). From these simple oxides, the formation of complex oxides requires a minimum temperature of 800°C. The synthesis of single phase spinel compounds Cu2+1‐2x Cu1+xFe2+xO4±δ is realized for 0.1 ≤ x ≤ 0.5, using specific temperature – p(O2) – conditions for a given value of x. Remarkably, to achieve our goal, we found that the increase of x implies that of the reaction temperature and/or a decrease of the p(O2) in the reaction gas stream. Besides, a single phase spinel CuFe2O4 does not exist in the temperature / p(O2)‐field investigated. Using the results of XRD ‐ phase analysis, T ‐ p(O2) – x – diagrams were constructed. These diagrams allow the prediction of phase compositions expected for different synthesis conditions. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
10.
J. H. Yu J. H. Kim D. S. Park T. S. Jeong C. J. Youn K. J. Hong 《Crystal Research and Technology》2010,45(10):1050-1056
Zn1‐xCdxO layers were deposited on the sapphire substrate using the radio‐frequency magnetron co‐sputtering system. The grown Zn1‐xCdxO layers were carried out in the post‐annealing treatment for 1 min at the 800 °C oxygen‐ambient by the rapid thermal annealing (RTA) method. X‐ray diffraction (XRD) experiment shows that the Zn1‐xCdxO layers are changed from the single phase of the hexagonal structure at 0≤x ≤0.08 to the double phase of hexagonal‐and‐cubic structure at x =0.13. Thus, the maximum Cd‐composition ratio with the hexagonal structure was found out to be x =0.08. Also, the crystallinity of Zn1‐xCdxO layers at x =0.13 was remarkably improved by the RTA annealing treatment. This crystal quality improvement was thought to be associated with the relaxation of the compressive strain remaining in the Zn1‐xCdxO layers. Therefore, the results of XRD and transmittance lead that the crystal quality of the Zn1‐xCdxO layers forming the hexagonal ZnO phase is better than that forming the cubic CdO phase. Consequently, the reliable formation and the crystallinity of the Zn1‐xCdxO layers were achieved by using the RTA method of short‐time thermal‐annealing at the high temperature. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
11.
H. Kim-Chauveau E. Frayssinet B. Damilano P. De Mierry L. Bodiou L. Nguyen P. Vennéguès J.-M. Chauveau Y. Cordier J.Y. Duboz R. Charash A. Vajpeyi J.-M. Lamy M. Akhter P.P. Maaskant B. Corbett A. Hangleiter A. Wieck 《Journal of Crystal Growth》2012,338(1):20-29
We present the growth optimization and the doping by the metal organic chemical vapor deposition of lattice-matched Al0.82In0.18N bottom optical confinement layers for edge emitting laser diodes. Due to the increasing size and density of V-shaped defects in Al1?xInxN with increasing thickness, we have designed an Al1?xInxN/GaN multilayer structure by optimizing the growth and thickness of the GaN interlayer. The Al1?xInxN and GaN interlayers in the multilayer structure were both doped using the same SiH4 flow, while the Si levels in both layers were found to be significantly different by SIMS. The optimized 8×(Al0.82In0.18N/GaN=54/6 nm) multilayer structures grown on free-standing GaN substrates were characterized by high resolution X-ray diffraction, atomic force microscopy and transmission electron microscopy, along with the in-situ measurements of stress evolution during growth. Finally, lasing was obtained from the UV (394 nm) to blue (436 nm) wavelengths, in electrically injected, edge-emitting, cleaved-facet laser diodes with 480 nm thick Si-doped Al1?xInxN/GaN multilayers as bottom waveguide claddings. 相似文献
12.
N. M. Gasanly 《Crystal Research and Technology》2003,38(11):962-967
The linewidths of Raman‐active intralayer compressional modes in GaS1‐xSex layered mixed crystals (0 ≤ x ≤ 1) have been measured in the 10‐300 K temperature range to study the anharmonic effect as a function of compositional variation and temperature. It was found that the anharmonicity increases with an increase in substitutional disorder. The cubic (three‐phonon) processes with energy conservation is responsible for the anharmonic contribution to the broadening of the intralayer phonon lines with temperature. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
13.
I. V. Bodnar V. F. Gremenok W. Schmitz K. Bente Th. Doering 《Crystal Research and Technology》2004,39(4):301-307
The (CuInSe2)x(2ZnSe)1‐x and (CuInTe2)x(2ZnTe)1‐x solid solution crystals prepared by Bridgman method and chemical vapor transport have been studied. The nature of the crystalline phases, the local structure homogeneity and composition of these materials have been investigated by X‐ray diffraction (XRD) and Electron Probe Microanalysis (EPMA) methods. The analysis revealed the presence of chalcopyrite‐sphalerite phase transition between 0.6 ≤ X ≤ 0.7. Lattice constants, value of σ position parameter and bond length between atoms were also calculated. It was found that the lattice parameters exhibit a linear dependence versus composition. The transmission spectra of solid solution crystals in the region of the main absorption edge were studied. It was established that the optical band gap of these materials changes non‐linearly with the X composition. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
14.
A. A. Wronkowska A. Wronkowski . Skowroski F. Firszt 《Crystal Research and Technology》2010,45(6):625-633
Spectroscopic ellipsometry in the infrared spectral range 250‐5000 cm‐1 is used for analysis of the dielectric response of Zn1‐x‐yBexMgySe and Zn1‐x‐yBexMnySe crystals grown by a high‐pressure Bridgman method. Ellipsometric spectra display features in the spectral range 390‐500 cm‐1 associated with BeSe‐type phonon modes. In the optical spectra of Zn1‐x‐yBexMgySe crystals both BeSe‐type and MgSe‐type lattice absorption bands are detected. The MgSe‐like modes are located at approximately 300 cm‐1. The complex dielectric functions can be reproduced using a model with two or three and one or two classical damped oscillators corresponding to the BeSe‐like and the MgSe‐like transverse‐optical phonon modes, respectively. The frequencies of longitudinal‐optical phonons have been derived from the dielectric loss functions. A red‐shift of the BeSe‐like phonons frequencies with a mean rate 0.42 cm‐1 (0.50 cm‐1) per mole percent of Mg (Mn) incorporated to the alloy has been found for examined concentration range x, y ≤ 0.25. A noticeable damping the intensities of BeSe‐type modes with increasing fraction of Mg and Mn dopant is observed in comparison to the strengths of BeSe‐type modes in Zn1‐xBexSe crystals. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
15.
N. M. Gasanly 《Crystal Research and Technology》2010,45(5):525-528
The optical properties of the TlInS2xSe2(1‐x)mixed crystals (0.25 ≤ x ≤ 1) have been investigated through the transmission and reflection measurements in the wavelength range of 400–1100 nm. The optical indirect band gap energies were determined by means of the analysis of the absorption data. It was found that the energy band gaps decrease with the increase of selenium atoms content in the TlInS2xSe2(1‐x)mixed crystals. The transmission measurements carried out in the temperature range of 10–300 K revealed that the rates of change of the indirect band gaps with temperature are γ = –9.2×10–4 eV/K, –6.1×10–4 eV/K, –4.7×10–4 eV/K and –5.6×10–4 eV/K for TlInS2, TlInS1.5Se0.5, TlInSSe and TlInS0.5Se1.5 crystals, respectively. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
16.
Abu Bakr El‐Bediwi 《Crystal Research and Technology》2005,40(7):688-691
Using x‐ray diffractometry, double bridge method and dynamic resonance technique structure, electrical resistivity, elastic modulus, internal friction and thermal diffusivity of Pb63‐xSn30Sb7Cux [x=0 or x≤2.5] quaternary melt spun alloys have been investigated. Adding Cu to PbSn30Sb7 decreases electrical resistivity, elastic modulus and internal friction. The PbSn30Sb7Cu1 melt spun alloy has better properties as bearing alloy, such as low electrical resistivity, high elastic modulus and adequate internal friction, compared with the Pb88Sn10Cu2 alloy used for automotive applications (FIAT Normalizzazione). That means, it has good properties as lead free (non‐toxic) bearing alloy. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
17.
J. Castro J. Naranjo L. Durn L. Melndez J. R. Fermin J. Cendros C. A. Durante Rincn 《Crystal Research and Technology》2006,41(10):946-949
Ingots of the CuAlxGa1‐xSe2 (0 ≤ x ≤ 1) alloys system were prepared by direct fusion of the stoichiometric mixture of the elements. The analysis of X‐ray Powder Diffraction data showed the presence of one single phase with chalcopyrite tetragonal structure at room temperature for all the studied compositions. The lattice parameters, a and c, and the bond lengths were calculated. The phase transition temperatures were obtained by the onset method from Differential Thermal Analysis measurements performed on samples sealed in evacuated quartz ampoules. Fusion or transition enthalpies were determined from the area of the corresponding DTA peak. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
18.
The influence of the Cu‐content in the quaternary compounds CuxAg1‐xInTe2 (0 ≤ x ≤1) on the structural properties of the bulk material was discussed. Bulk ingot materials of CuxAg1‐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) 相似文献
19.
ESR and optical absorption of Cu2+ were measured in xNa2O(100?x)B2O3 (1 ≤ x ≤ 75), x ZnO(100?x)B2O3 (46 ≤ x ≤ 64) and x Pb(100?x)b2O3 (20 ≤ x ≤ 75) glasses, where x is expressed in mol.%. Spin hamiltonian parameters and ligand field absorption energy changed abruptly in the regions of 15 ≤ x ≤ 23 and 37 ≤ x ≤ 55 in the soda system, while both parameters were hardly dependent upon the glass composition in zinc and lead systems. The magnitude of micro-environmental fluctuation of Cu2+-complexes in the glasses was estimated qualitatively and correlated with the distribution of the strength of π-bonding between cupric ion and oxygen in the glass. Typical network modifiers and intermediates behaved differently, especially in the composition region of invert glass; the large deformation of the coordination sphere of Cu2+ in lead glasses due to the stronger PbO bond resulted in the large distribution of . The situation was reverse in the case of soda glasses. 相似文献
20.
N. M. Gasanly 《Crystal Research and Technology》2010,45(11):1141-1144
The optical properties of TlInS2xSe2(1‐x)mixed crystals (0.25 ≤ x ≤ 1) have been studied at room temperature through the transmittance and reflectivity measurements in the wavelength range of 400–1100 nm. The spectral dependence of the refractive index for all compositions of studied crystals were obtained. The dispersion of the refractive index is discussed in terms of the Wemple–DiDomenico single‐effective‐oscillator model. The compositional dependencies of refractive index dispersion parameters: oscillator energy, dispersion energy and zero‐frequency refractive index were revealed. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献