Interface structure dependent step free energy and grain growth behavior of core/shell grains in (Y, Mg)-doped BaTiO3 containing a liquid phase

Abstract

The grain growth behavior of 92BaTiO(3)-3Y(2)O(3)-3MgO-2SiO(2) (mol.%) containing a liquid phase has been systematically investigated with respect to oxygen partial pressure (P-O2). Bi-layer samples, where a pre-sintered polycrystalline sample is coupled with a single crystal of pure BaTiO3, were heat-treated under an atmosphere ranging from wet H-2 (P-O2 similar to 10(-13)-10(-14) atm) to air (P-O2 similar to 0.2 atm) simulating industrial conditions. The single crystal provided a significantly larger driving force for grain growth than matrix grains, permitting an elaborate analysis. Considering the bi-layer sample as a single system, a clear shift of grain growth behavior was observed: (pseudo) normal grain growth (NGG), delayed abnormal grain growth (AGG), and stagnant grain growth (SGG), as the atmosphere became more oxidizing. The shift was accompanied by structural change of solid/liquid interfaces and grain boundaries and successfully explained by the step free energy effect, emphasizing the validity of interface control in BaTiO3 with a solid/liquid interface.