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The flash sintering process has been regarded as a noble method to densify ceramic materials. The distinctive feature of the flash sintering is the reduced sintering time which is caused by the electric field. In this study, flash sintering of the hydroxyapatite bioceramics was carried out at temperatures of 900–1200°C and electric fields of 500–1200 V/cm. Dense sintered sample was prepared in a short time within 10 seconds. Electric field required for flashing became reduced as the furnace temperature increased. Abrupt rise of the sample temperature of up to 120°C was observed when the flash occurred. The incubation time for flashing became shorter with increasing temperature and electric field. The flashing was found to occur at lower temperature and lower electric field in vacuum than in air. Microstructure of the flash sintered sample was not different from that of conventionally sintered sample. [ABSTRACT FROM AUTHOR]

Systematic statistical analysis of the microstructural changes in 3 mol% yttria-stabilized zirconia was performed after flash sintering by alternating current (AC). The micrographs in the gauge section of the specimen were identical to those from DC flash sintered samples while no evident electrode effect was present for AC flash sintered samples. However, finite element modeling revealed a temperature gradient from the surface to the volume of the sintered body. Microstructure gradients, across the width of gauge section, were revealed for the AC flash sintered sample. Classical grain growth models due to Joule heating were insufficient in justifying the microstructural evolution under the simulated temperature distribution. Bimodal grain diameter distributions in flash sintered samples were observed. Therefore, it is proposed that faster grain growth mechanisms activated on a fraction of the grains by electric field/current occurred during flash sintering, and is responsible for the instantaneous grain growth. [ABSTRACT FROM PUBLISHER]

Abstract: Three-dimensional Mn3O4 nanostructures were synthesized by a soft chemistry templating process using a block copolymer as the structure-directing agent. This material has a unique structure of intertwining nanowires which are grown from faceted Mn3O4 particles and aligned spatially perpendicular to or along each facet. The magnetic measurements of such nanostructured films show clear signs of magnetic shape anisotropy, indicating that this templating synthesis approach could be a promising method to develop Mn3O4 nanostructures with desired anisotropic properties through dimensionality control. [Copyright &y& Elsevier]

BaTiO3 nanoparticles were synthesized by combustion spray pyrolysis using a 1:1 molar ratio of oxidizer and fuel. To prepare solution precursor, Ba(NO3)2, TiO(NO3)2, CH6N4O, and NH4NO3 with the molar ratio of 1:1:4:2.75 were mixed in distilled water with 10% ethyl alcohol. A 0.01 M solution was ultrasonically sprayed into a quartz tube heated at 800 °C. The number concentration of droplets was decreased and large particles were removed by passing the droplets through a metal screen filter. The synthesized particles were well crystallized tetragonal BaTiO3. The median diameter of BaTiO3 was 60 nm. [Copyright &y& Elsevier]