[en] The resolution function of an X-ray triple-crystal diffractometer on a rotating-anode source has been studied both experimentally and theoretically. Three different experimental configurations were used, with perfect germanium, distorted germanium and pyrolytic graphite as monochromator and analyser, leading to changes in the resolution of two orders of magnitude. The results are compared with a Gaussian description of the resolution function and it is found that this describes the width of the central part with an accuracy of better than 25%. The wings of the resolution in the high-resolution mode show the effect of the non-Gaussian resolution elements but these are reproduced by a full numerical convolution theory of the resolution function. (orig.)

[en] A comparative study of the nucleation of In enriched islands in In_0.2Ga_0.8As/GaAs multilayers grown on top of GaAs or AlAs buffers deposited on GaAs substrates with various miscut parameters was performed by using X-ray diffraction, transmission electron microscopy (TEM) and atomic force microscopy (AFM) techniques. Experimental results showed that the evolution of the self-assembly strongly depends on the miscut parameters and the morphology of the buffer/multilayer interface. For the samples with the same nominal strain misfit between the bilayers the nucleation is enhanced for the larger initial miscut on the substrate and the degree of the lateral ordering across the interface is promoted by the morphology of the underlying AlAs buffer layer

[en] A 'hot wall epitaxy' is applied to grow PbTe thin films on sapphire substrates with BaF₂ buffer layer deposited by molecular beam epitaxy (MBE). The microstructural and strain state characteristics of PbTe layer were examined with high resolution X-ray diffraction techniques. The epilayer is composed of two (111)PbTe parallel (0001)Al₂O₃ epitaxially oriented domain variants. The domains are azimuthally rotated and their interfacial directions relative to the substrate are [011-bar]PbTe parallel 21-bar1-bar0Al₂O₃ and [1-bar54-bar]PbTe parallel 21-bar1-bar0Al₂O₃, respectively. Another possible alignment of the domain variant corresponds to 31-bar2-barPbTe parallel 31-bar2-bar0Al₂O₃ orientation. The strain state analysis of PbTe layer points to its relaxation via domain formation and high dislocation density generation in the lattice. Despite the domains formation the measured mobility of electron carriers is approximately 1600 cm²/V s and 30 000 cm²/V s at 300 K and 77 K, respectively. The theoretical analysis of the measured electrical properties indicates that the scattering by acoustic and optical phonons is the factor affecting the conduction process

[en] Structure refinements of CaLaBaCO superconductors having constant nominal cationic charge of +7.25 are reported, using X-Ray powder diffraction (XRPD) data. The cationic charge in the samples is balanced by substituting Ca⁺² for La⁺³ and La⁺³ for Ba⁺². The observed structural changes in this system and their effect on T_c are discussed. (orig.)

[en] X-ray anomalous scattering measured with a high-resolution triple-crystal diffractometer was analysed in terms of different models of microdefects present in the bulk of InP crystal. The observed broadening of the Laue reflections is consistent with the formation of large aggregations of the diffuse intensity including both Huang and Stokes-Wilson regions in comparison with the experimental data revealed that these aggregations consist of vacancy loops occupying predominantly the (111) plane

[en] The Moessbauer spectroscopy, X-ray diffraction and electron microscopy were applied to analyse samples of a Ti-3at% Mo-0.13at%⁵⁷Fe alloy in which phase transitions were induced by various treatments. In the as quenched alloy, two martensitic phases were found to be hcp-α' and orthorhombic α''. An amount of about 8-10% ω-phase (in additon to α' and α'') appeared in a quenched sample which was soaked at 92 kbar for 20 h. For a quenched and cold-worked sample, the X-ray and electron microscopy results were not conclusive whereas the Moessbauer spectrum contained an ω-line with a relative spectral area Asub(ω/A)=0.15. In a cold-worked sample that was aged at 350⁰C for 24 h a metastable phase, known as theta, appeared in addition to the ω-phase. The spectrum of a sample aged at 350⁰C for 3.5 h (not cold-rolled) consists of α', α'' and theta lines

[en] Changes of crystal structure induced by high-pressure soaking (hps) up to 9.2 GPa were studied in Ti with 3 to 35 at.% Mo alloys which were in the as-quenched metastable state. The retained structure was analysed by X-ray diffractography and transmission electron microscopy. It was observed that after application of critical pressure, ω phase appears or its quantity increases in all crystal structures that are observed usually in Ti-base alloys and consisting of α',α' + β + ω,β + ω or β phases. Strong diffuse scattering patterns created by short range order in displacement of atomic rows were observed. The β → α' high-pressure transition was observed first in Ti-base alloys. Analysis of the relative stability of all different structures with regard to hps was performed using detailed on Debye temperature, density of electronic states at Fermi level and other parameters. (orig.)

[en] Reciprocal space mapping in non-coplanar diffraction geometry using a triple-crystal diffractometer is applied to study strained In_0.2Ga_0.8As/GaAs multilayer. The modelling accounts for the measured integrated intensities of the satellites in the simulation of the reciprocal space map to provide compositional profile of In distribution in the nucleated islands on the interfaces. Theoretical approach to calculate the intensity in this unconventional geometry is discussed

No abstract available

[en] First results of an x-ray diffraction study of a newly found substantial reduction in radiation damage by permanent magnetic fields in InSb single crystals during implantation with In⁺ ions are discussed. The data indicate that, in the presence of a permanent magnetic field, there is a decrease in formation of point defects, and in their trend to form clusters. These observations are supported by Rutherford backscattering measurements. A scheme to perform grazing-incidence measurements using a diffractometer equipped with parallel beam optics is presented. (author)