Static Displacements and Short-Range Order in Ni-14 at. % Ir Alloy

In this paper, we are proposing a novel method to estimate static displacements of atoms caused by size effects in fcc substitutional binary polycrystalline solid solutions. Fourier transforms of static displacements of the atoms on every considered shell were calculated using the equations that include dynamical matrix and Fourier transform of interatomic forces. Short-range order parameters on the first seven shells of Ni-14 at. % Ir alloy have been identified from X-ray diffuse scattering intensity by accounting microscopic static displacements of atoms on a particular shell. Pairwise interatomic potentials on the considered shells and critical temperature of disorder-order phase transition were calculated using values of short-range order parameters.

A Study of Defects in InAs/GaSb Type-II Superlattices Using High-Resolution Reciprocal Space Mapping

In this paper, he study of defects in InAs/GaSb type-II superlattices using high-resolution an x-ray diffraction method as well as scanning (SEM) and transmission (TEM) electron microscopy is presented. The investigated superlattices had 200 (#SL200), 300 (#SL300), and 400 (#SL400) periods and were grown using molecular beam epitaxy. The growth conditions differed only in growth temperature, which was 370 °C for #SL400 and #SL200, and 390 °C for #SL300. A wings-like diffuse scattering was observed in reciprocal space maps of symmetrical (004) GaSb reflection. The micrometer-sized defect conglomerates comprised of stacking faults, and linear dislocations were revealed by the analysis of diffuse scattering intensity in combination with SEM and TEM imaging. The following defect-related parameters were obtained: (1) integrated diffuse scattering intensity of 0.1480 for #SL400, 0.1208 for #SL300, and 0.0882 for #SL200; (2) defect size: (2.5–3) μm × (2.5–3) μm –#SL400 and #SL200, (3.2–3.4) μm × (3.7–3.9) μm –#SL300; (3) defect diameter: ~1.84 μm –#SL400, ~2.45 μm –#SL300 and ~2.01 μm –#SL200; (4) defect density: 1.42 × 106 cm−2 –#SL400, 1.01 × 106 cm−2 –#SL300, 0.51 × 106 cm−2 –#SL200; (5) diameter of stacking faults: 0.14 μm and 0.13 μm for #SL400 and #SL200, 0.30 μm for #SL300.

Estimation of the Critical Temperatures of Order-Disorder Phase Transitions in Cu-Au Alloys Using Short-Range Order Parameters

An expression for calculating the critical temperature of order-disorder transition in face-centered cubic alloys is developed with accounting of pairwise interatomic potential in the first eleven shells. Obtained expression was applied for the estimation of critical temperatures at Cu3Au, CuAu, and CuAu3alloys in comparison with experimental data from phase diagram of Cu-Au system. Magnitudes of the pairwise interatomic potential in considered alloys was computed using values of the short-range order parameters which were experimentally obtained from X-ray diffuse scattering intensity. In this computation, the Krivoglaz-Clapp-Moss approximation and Cowley equations were applied.

A neutron diffuse scattering study of PbZrO3and Zr-rich PbZr1–xTixO3

A combined neutron diffuse scattering study and model analysis of the antiferroelectric crystal PbZrO3is described. Following on from earlier X-ray diffuse scattering studies, supporting evidence for disordering of oxygen octahedral tilts and Pb displacements is shown in the high-temperature cubic phase. Excess diffuse scattering intensity is found at theMandRpoints in the Brillouin zone. A shell-model molecular dynamics simulation closely reproduces the neutron diffuse scattering pattern. Both in-phase and antiphase tilts are found in the structural model, with in-phase tilts predominating. The transition between disordered and ordered structure is discussed and compared with that seen in Zr-rich PbZr1−xTixO3.

Rapid Estimation of the Height-Height Correlation Functions from the Synchrotron X-Ray and AFM Study of very Thin SnO2/α-Al2O3(0001) FILM

For the defective semiconductor SnO2 thin film epitaxially grown on sapphire, height-height correlation functions are evaluated from x-ray scattering and atomic force mi-croscopy(AFM) by a quick method. The small value [Formula: see text] implies that the interfaces are fairly well correlated. This is consistent with the well-defined oscillation in the longitudinal diffuse scattering intensity.