L. N. Dem'yanets

Chemistry and Kinetics of ZnO Growth from Alkaline Hydrothermal Solutions

Special features (polar growth and nonstoichiometry) of ZnO single crystals grown on seed plates of various crystallographic orientations in the ZnO–KOH–H2O and ZnO–KOH–LiOH–H2O hydrothermal systems are analyzed. The growth proceeds via the interaction of ZnO2-2 anions with crystal surfaces, and its rate depends on the atomic structure and electric charge of the surface. The mechanism underlying the influence of Li+ ions on polar ZnO growth is considered. Partial replacement of Zn2+ by Li+ decreases the positive charge on the (0001) face and hinders the attachment of ZnO2-2 anions. The incorporation of Li ions into the (0001¯) face decreases its negative charge and accelerates growth in the [0001¯] direction.

Hydrothermal Synthesis of K2ZrSi6O15 , K2ZrSi3O9 , K2ZrSi2O7, and ZrSiO4 in the System KOH–ZrO2–SiO2–H2O

The phase relations in the KOH–ZrSiO4–H2O, KOH–ZrO2(cr)–SiO2–H2O, and KOH–ZrO2(nanocr)–SiO2–H2O systems were studied at 400°C, 0.1 GPa, and KOH concentrations from 2 to 46 wt %. The crystallization fields of K2ZrSi6O15, K2ZrSi3O9, K2ZrSi2O7, and ZrSiO4 were located. The potassium zirconosilicates have open-framework structures made up of corner-shared ZrO6 octahedra and SiO4 tetrahedra. The composition of the crystallizing silicates is shown to depend on the nature of the starting Zr- and Si-containing materials.

One-dimensional SnF2 single crystals in the inner channels of single-wall carbon nanotubes: I. Preparation and basic characterization

One-dimensional (1D) SnF2 single crystals have been obtained by crystallization from melt in the inner channels of single-wall carbon nanotubes (SWCNTs). SWCNTs with an inner diameter of 1.02–1.4 nm, synthesized by electric-arc discharge and chemically purified, were used for incorporation. The synthesized 1D SnF2 single crystal-SWCNT composites are basically characterized by X-ray diffraction, energy-dispersive analysis, electron microscopy, and chemical analysis. The characteristic motifs of tin cation distribution in the SWCNT inner channel confirm the formation of SnF2 single crystals.

Zinc oxide single crystals: Influence of temperature and orientation of crystals on their mechanical properties

AbstractZinc oxide single crystals are grown hydrothermally and their microhardness is measured on different {hkil} faces in the temperature range from liquid nitrogen temperature to 900°C. The coefficient K1C of fracture roughness and the surface energy γ of fracture are estimated. The (0001) plane of a positive monohedron is characterized by the maximum hardness and plasticity over the whole temperature range studied. The shape of indenter prints and dislocation rosettes on the planes of monohedra, hexagonal prisms, and the pyramid are studied. The indenter print on the basal plane has an isotropic shape, whereas on the planes of prisms and the pyramid the prints indicate the first-kind anisotropy of mechanical properties. The first-kind anisotropy coefficient k equal to Hmax/Hmin increases with an increase in the temperature for the

Phase Relations in the Systems LiOH–GeO2–H2O and LiOH–SiO2–H2O at 500°C and 0.1 GPa

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Lasing in low-dimensional ZnO objects: Interrelation between the crystallite morphology and feedback formation mechanisms

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Hydrothermal crystallization in the systems LiOH-MO2-GeO2-H2O (M = Ti, Sn) at 500°C and 0.1 GPa:Li2Ti[5]Ge[4]O5 and Li2Ge[6]Ge2[4]O6 phase relations

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