Articles you may be interested in Symmetry determination on Pb-free piezoceramic 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 using convergent beam electron diffraction method

In this investigation we have studied how the presence of a liquid phase affects the grain morphology and grain growth kinetics in Alz03 at 1800°C using the growth of both matrix grains and large spherical single-crystal seeds growing into the matrix. The growth rates of the matrix grains were found to decrease in the following order: undoped AI2O3, A1203 with anorthite, Al2o3 with anorthite and MgO, and AI2O3 with MgO. Except for the samples doped with MgO alone, the matrix grains were faceted and appeared tabular in polished sections. In samples containing anorthite both with and without MgO, the single-crystal seeds exhibit basal facets with continuous liquid films and slow growth in the (0001) relative to all other crystallographic directions. When only MgO is added, the growth of the single-crystal seeds was not isotropic; however, no faceting was observed. We discuss how anisotropic growth rates caused by the anorthite additions can stimulate discontinuous grain growth in &03.

Barium titanate precursors with Ba/Ti ratios ranging from 2: 1 to 1 : 9 were prepared by controlled hydrolysis of mixed barium and titanium species in an alcohol medium. Details of the synthesis and characterization of the resultant products are given. Amorphous powders precipitated by hydrolysis from ethanol solutions of barium and titanium alkoxides crystallize to singleor two-phase 1 : 2 and 1 : 5 compounds at =700°C. These compounds transform at higher temperatures to other known crystalline phases, the 1 : 5 phase being maintained metastably to =lloooc.