Reactive-templated grain growth of Bi_1/2(Na,K)_1/2TiO₃: Effects of formulation on texture development

In this paper we report the effects of formulation on texture development for the "reactive-templated grain growth" (RTGG) of Bi_1/2(Na,K)_1/2TiO₃ (BNKT). The solids formulation for BNKT was systematically varied by prereacting to well-defined alkali and bismuth titanates (Na₂Ti₃O₇ (N₂T₃), K₂Ti₂O₅ (K₂T₂), and Bi₂Ti₄O₁₁ (B₂T₄)). Use of these precursors in different BNKT formulations determined that the amount of expansion associated with reacting dry-pressed compacts at 600-800°C could be influenced by formulation. Lotgering factors (F_00l) derived from Θ/2Θ X-ray diffraction scans indicated that the formulation route strongly affected the {00l} texture development in tape-cast and sintered specimens. Prereacting alkali carbonates with TiO₂ to form N₂T₃ and K₂T₂ inhibited texture development in RTGG-processsed BNKT. However, when Bi₂O₃ was prereacted to form B₂T₄, the measured F_00l increased from 0.5 to 0.7.