ZnO/TiO2 nanocomposites with several ratio of the components were prepared by sol-gel method using titanium isopropoxide and titanium butoxide as titania precursors. Phase formation and photocatalytic activity of ZnO/TiO2 nanocomposites depend on ratio of the components and calcination temperature. The photocatalytic activity in dependence on calcination temperasture, phase composition was determined by degradation of methylene blue solution under Hg lamp and solar light imitating illumination. The highest photocatalytic activity showed ZnO/TiO2 nanocomposites containing 99 mol.% ZnO and 50 mol% ZnO when hexagonal ZnTiO3 phase was formed. ZnO/TiO2 nanocomposites exhibited enhanced photoactivity under solar light with respect to Hg lamp irradiation.
The formation of high temperature composites in W-C-B system from fine-grained powders in dependence on the ratio of components by using reactive spark plasma sintering was studied. The mixture of W2C and C nanoparticles was used as tungsten and carbon precursors. The W2C and carbon mixture with different ratio of components was prepared by reduction of WO3 in presence of CH4 in nitrogen inductively coupled plasma. The specific surface area of the mixture was in the range of 36-42 m 2 /g in dependence on the content of carbon. The W2C and carbon particles were mixed mechanically with amorphous boron and densified using the spark plasma sintering technique at 1500-1700 °C and pressure of 30 MPa for 4 minutes. The sintered bodies contained WB2 and B4C phases. The ratio of phase depends on the content of the components in the raw mixture.
Microwave assisted and molten salts synthesis were extended for preparation of ceria (10 mol%; 15 mol%) stabilized zirconia and their parameters and sinterability were compared with that of particles prepared by the sol-gel combustion method. As-prepared powders by using microwave assisted and sol-gel combustion synthesis contained single tetragonal ZrO2 phase but powders prepared by molten salts combustion method contained two ceria-stabilized tetragonal phases with different content of ceria. The crystallite size of the as-prepared zirconia phases was in the range of 3.2-9.4 nm and the average particles size is in the range of 7.6-24.6 nm depending on the synthesis method. Additional calcination of the powders up to 1000 °C led to increase of crystallite size in the range of 19-25 nm and decrease of specific surface area in the range of 18-21 m 2 /g and partial formation of monoclinic phase of ZrO2. Bulk materials with fine-grained microstructure (0.8-1.6 µm) and density in the range of 95.2-97.2 % were obtained by spark plasma sintering at 1280-1310 °C during 3 min. Nanoparticles prepared by microwave assisted synthesis showed better sinterability and higher density.
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