Unusual quasi-two-dimensional crystals of a regular triangular shape, self-formed in the process of obtaining a coordination polymer based on phenazine and silver, are described and studied. X-ray diffraction studies were carried out, the interplanar distance was determined, and the spectra of Raman scattering were obtained. A mechanism is proposed that can cause the appearance of triangular crystals from nuclei of hexagonal symmetry.

Thick β-Ga2O3 homoepitaxial films have been grown on (2¯01) commercial substrates by mist-CVD with gallium acetylacetonate precursor for the first time. The growth rate of about 2 μm/h has been reached, which is unavailable for any other known epitaxial technique. The layer is characterized by the constant thickness and reasonable structure quality due to low stressed interface.

Gallium Oxide is a prospective ultra-wide band -gap semiconductor for high -voltage electronics. Bulk beta-Ga2O3 crystals can be utilized as substrates for device structures. The biggest challenge encountered is to grow low defect density wafers with high crystal perfection. In this work a boule with a diameter of about 20 mm and a height of 20 mm was grown by Czochralski method. The separate plates with dimensions of approx. (10 x 5 x 3) mm3 were cleaved out from the crystal along the (100) cleavage planes. XRD investigation demonstrated that the crystal is a monoclinic single -phase structure which is characterized by broad rocking curves. The etch pits density revealed by selective wet etching appeared to be high and was estimated as 2 & sdot; 107 cm - 2. The series of post-growth heat treatments was applied to eliminate these drawbacks. Annealing at 1100 degrees C during 5 h had the most effect on the crystal structure. Namely, its coherent-domain-size value increased over 400 nm, domain misorientation dropped below the arcminute. The crystal developed higher stoichiometry and higher crystalline perfection. Annealing at the same temperature, but for duration of 11 h dramatically worsen all the parameters of the crystal in combination with its fragmentation in smaller-sized domains. The etch pits density finally decreased 40 -fold and took a value of 5 & sdot; 105 cm - 2.

Thick (3- Ga 2 O 3 homoepitaxial films have been grown on (201) commercial substrates by mist-CVD with gallium acetylacetonate precursor for the first time. The growth rate of about 2 mu m/h has been reached, which is unavailable for any other known epitaxial technique. The layer is characterized by the constant thickness and reasonable structure quality due to low stressed interface.

•Gallium Oxide (β-Ga2O3) crystals are utilized as substrates for high-power devices.•Thermal annealing was applied to enhance the perfection of bulk (100) β-Ga2O3 crystals.•Annealing led to increase in coherent-domain-size value and decrease in domain misorientation.•Annealing led to development a higher stoichiometry and higher crystalline perfection.•Annealing decreased etch pits density 40-fold.

Selective wet etching technique was applied to commercial ((2) over bar 01) beta-Ga2O3 single crystal substrates. Some etching recipes allowed us to reveal sharp etch pits on the surface of the substrates. The geometric shape, orientation and density of etch pits were investigated in as-delivered specimens. An observation of mutual location of the etch pits indicates the likely formation low-angle grain boundaries that can form upon heating. Selective wet etching technique was applied to commercial ((2) over bar 01) beta-Ga2O3 single crystal substrates. Some etching recipes allowed us to reveal sharp etch pits on the surface of the substrates. The geometric shape, orientation and density of etch pits were investigated in as-delivered specimens. An observation of mutual location of the etch pits indicates the likely formation low-angle grain boundaries that can form upon heating.

The tribological and mechanical tests of bulk substate crystals of gallium oxide beta-polymorph grown by the EFG technique were carried out. The correlation of coefficient of friction and wear coefficient with hardness is discussed. It is shown that the smooth, epi-ready surface of ((2) over bar 01) Ga2O3 samples has an extremely low resistance to abrasion by a sapphire ball. At the same time, the surface of the beta-Ga2O3 wafer that has not undergone a complete post-growth processing cycle has high mechanical properties. It is pointed out that this difference can be due to deformation defects, which are entered into the subsurface layers during the mechanical impact on the semiconductor material.

A set of LiFePO4 samples has been studied by small-angle X-ray scattering (SAXS). Using the technique of artificial neural networks, the shape of SAXS curves has been reconstructed taking into account the hardware function. Estimates of homogeneitiessizes and shapes in the studied LiFePO4 samples have been obtained.

A set of LiFePO4 samples has been explored with the help of small-angle x-ray scattering (SAXS). Using the technique of artificial neural networks the shape of SAXS curves has been rebuilt considering the hardware function. The estimations of homogeneities sizes and shapes in the studied LiFePO4 samples have been obtained.

A new method for growth of Au-catalyzed lateral Ga(In)AsP nanostructures in a quasi-closed volume from a vapor source under semi-equilibrium conditions has been studied. Varied time-temperature conditions and nucleation modes were examined. It was found that lateral nanostructures elongated in the [1 (1) over bar0] direction are formed on a (100) GaAs substrate at about 500 degrees C. Raising the growth temperature is accompanied by a significant change of the morphology of the nanostructures. The modified surface has a random textured structure with predominant pyramidal faceting. Changes in the alloy composition of the nanostructures were studied.

The tribological experiment applied to the gallium oxide wafer led to changes in its structure which can reduce the single crystal perfection. The effect of mechanical wear on the subsurface layers of the β-Ga2O3 single crystal wafers applied to the (2‾01) plane is studied. A decrease in crystallinity within a mosaic structure appearing in the worn samples is revealed with a help of ω-scan analysis, performed by XRD. SEM analysis of the wear track relief of the worn samples showed an emergence of the lamellas framed by domain walls as a result of single crystal splitting.

α-Ga2O3/α-Cr2O3 heterostructures with a corundum structure were obtained by chloride vapor phase epitaxy and magnetron sputtering. The structural, electrical conductive and photoelectrical properties of the obtained samples were studied. It was established that the α-Ga2O3/α-Cr2O3 heterostructures exhibits weak rectifying properties and in comparison with α-Ga2O3 films has a higher response speed when exposed to ultraviolet radiation.

Unusual quasi-two-dimensional crystals of a regular triangular shape, self-formed in the process of obtaining a coordination polymer based on phenazine and silver, are described and studied. X-ray diffraction studies were carried out, the interplanar distance was determined, and the spectra of Raman scattering were obtained. A mechanism is proposed that can cause the appearance of triangular crystals from nuclei of hexagonal symmetry.

The results of using a hybrid technology for the synthesis of ultrafine carbon powder material in an amorphous state are considered. Different modes of hybrid technology are proposed, including mechanochemical synthesis in a ball mill and the process of self-propagating sustainable combustion in a natural atmosphere to produce carbon powder materials (CPM) in an amorphous state. Using X-ray diffraction methods: diffractometric, radiographic, and small-angle X-ray scattering, heterogeneities of the CPM structure were studied. Areas of structural heterogeneity having a flat shape and containing up to 10 graphene-like layers are revealed.

An indium-phosphide InP sample subjected to the pore-generation procedure and then doped with S atoms is studied by the methods of X-ray diffraction analysis (XRD) and small-angle X-ray scattering (SAXS) (with Cu K α1 -radiation). The XRD data demonstrate that the sample consists of (coherent) aligned homogeneous components. A point detector is used to obtain, in the anomalous transmission mode by Borrmann, a set of SAXS curves at sample positions varied by azimuthal rotations. The SAXS data are used to simulate a 2D SAXS pattern for the sample under study, which makes it possible to determine the long-distance translation symmetry and, consequently, the presence of a superstructure. The interplanar distances in the superstructure in the directions (110) and (1 0) of the InP lattice are found to be ~260 and 450 nm, respectively. The symmetry group of the superstructure is determined as C 2 v in the (001) plane of the sample lattice.

The paper is devoted to the growth of thin SiC films by the method of substitution of atoms on macro-and mesoporous substrates of p-and n-type silicon of (100) orientation. On the mesoporous Si (100) substrates polycrystalline 3C-SiC films were formed, the crystallite size determined from XRD patterns was 27.5 nm. The obtained structures are studied by the methods of scanning electron and atomic-force microscopy, micro-Raman spectroscopy and X-ray diffraction analysis. (C) 2018 The Electrochemical Society.

AbstractAn indium-phosphide InP sample subjected to the pore-generation procedure and then doped with S atoms is studied by the methods of X-ray diffraction analysis (XRD) and small-angle X-ray scattering (SAXS) (with Cu K _α1-radiation). The XRD data demonstrate that the sample consists of (coherent) aligned homogeneous components. A point detector is used to obtain, in the anomalous transmission mode by Borrmann, a set of SAXS curves at sample positions varied by azimuthal rotations. The SAXS data are used to simulate a 2D SAXS pattern for the sample under study, which makes it possible to determine the long-distance translation symmetry and, consequently, the presence of a superstructure. The interplanar distances in the superstructure in the directions (110) and (1 0) of the InP lattice are found to be ~260 and 450 nm, respectively. The symmetry group of the superstructure is determined as C _2 v in the (001) plane of the sample lattice.

The small-angle X-ray scattering in calomel (univalent mercury chloride Hg 2 Cl 2 ) single crystals at low temperatures has been investigated. Data on the size of superstructural ferroelectric domains have been obtained for the first time. Lang measurements with anomalous X-ray transmission have made it possible to trace the temperature dynamics of crystal lattice of the high-temperature D 4 h phase of Hg 2 Cl 2 from 300 K to the Curie temperature (186 K) and the formation of ferroelastic domains in the temperature range of 186–100 K. The lowering of paraphase symmetry in the closest vicinity of the phase transition temperature is indicative of tricritical point transition.