Solid state phase transformation of BaB₂O₄ during the isothermal annealing process

Abstract

Solid-state phase transformation of BaB₂O₄ during the isothermal annealing process for both β to α and α to β were investigated using a platinum crucible. For the β-phase crystal at the α-phase stable temperature (> 925 °C), the β phase transforms to the α phase perfectly below the melting temperature of 1100 °C. Meanwhile, for the α-phase crystal at the β-phase stable temperature (< 925 °C), the α phase transforms to the β phase perfectly above 800 °C. There is some difference in phase transformation behaviour between bulk-shape crystals and the powder, caused by thermal stress.