Fabrication and Characterization of Dielectric ZnCrO Nanopowders and Thin Films for Parallel-Plate Capacitor Applications.

We report here the successful shape-controlled synthesis of dielectric spinel-type ZnCrO nanoparticles by using a simple sol-gel auto-combustion method followed by successive heat treatment steps of the resulting powders at temperatures from 500 to 900 °C and from 5 to 11 h, in air. A systematic study of the dependence of the morphology of the nanoparticles on the annealing time and temperature was performed by using field effect scanning electron microscopy (FE-SEM), powder X-ray diffraction (PXRD) and structure refinement by the Rietveld method, dynamic lattice analysis and broadband dielectric spectrometry, respectively. It was observed for the first time that when the aerobic post-synthesis heat treatment temperature increases progressively from 500 to 900 °C, the ZnCrO nanoparticles: (i) increase in size from 10 to 350 nm and (ii) develop well-defined facets, changing their shape from shapeless to truncated octahedrons and eventually pseudo-octahedra.

Graphene/semi-insulating single crystal CdTe Schottky-type heterojunction X- and γ-Ray Radiation Detectors.

We developed a new concept of X- and γ-ray radiation semiconductor detectors based on a large area graphene/semi-insulating single crystal CdTe Schottky-type heterojunction. These two terminal electronic devices can be easily fabricated by forming a Van der Waals contact between large area chemical vapor deposited graphene and CdTe substrates in air and at room temperature. This approach significantly reduces the fabrication cost and improves the reproducibility and stability of electrical properties.

X-ray topography of subsurface crystal layers.

New capabilities of the Berg-Barrett topographic method are demonstrated using a skew-asymmetric X-ray diffraction scheme for investigating structural changes near the surface of semiconductor materials. Specifying the X-ray extinction depth, the details of defects and strains are revealed with high resolution. Consequently, analysis of structural distortion of layers near the surface after various types of surface processing becomes more complete.

Structure diagnostics of heterostructures and multi-layered systems by X-ray multiple diffraction.

This article presents the results of research on multi-layered heterostructures by a modified calculation technique of multiple X-ray diffraction. The Al In Sb heterostructure and a Zn(Mn)Se/GaAs(001) multi-layered system were used as models to specify conditions for cases of coincidental coplanar three-beam or coincidental noncoplanar four-beam X-ray diffraction. These conditions provide the means for a high-precision determination of lattice parameters and strain anisotropy in layers.

Magnetic and structural changes in the near-surface epitaxial YLaFeO films after high-dose ion implantation.

The method of magnetic force microscopy was used to study the domain structure of various-thickness epitaxial YLaFeO iron-yttrium garnet films modified by high-dose implantation of N nitrogen ions. The results of multi-crystal x-ray diffractometry were analyzed, and a possible defect structure of garnets prior to and after implantation was identified. It was established that the reduction of magnetic losses observed after high-dose ion implantation is accompanied by the essential ordering of magnetic domains on the surface of implanted films.

Direct and inverse problems in x-ray three-crystal triple Laue case interferometry.

We study the mechanisms of forming x-ray moiré images arising under the action of one-dimensional rows of local concentrated forces at the output surface of a triple-crystalline triple Laue case interferometer for the cases of their orientation parallel and perpendicular to the vector of diffraction. The presence of constant phase shift of one of the interfering waves in the interferometer's analyzer results in the diminishing of period, contrast, and area of deformation moiré fringes. It is shown that the area of efficient interaction of phase and deformation moirés depends on both the magnitude of the constant phase shift and the magnitude and character of arrangement of local concentrated forces in rows.