Crystallization of a PbO‐BaO‐TiO ₂ ‐Al ₂ O ₃ ‐SiO ₂ Glass

Abstract

The phase development, microstructure development, and Curie temperature of PbO‐BaO‐TiO 2 ‐Al 2 O 3 ‐SiO 2 glass‐ ceramics were investigated by X‐ray diffractometry, electron microscopy, and dilatometry. The primary crystalline phase was perovskite titanate, which exhibited bulk nucle‐ ation. When the samples were heated at low temperatures, the Curie inversion was hindered and cubic perovskite was obtained. Increased heating temperature/time resulted in tetragonal perovskite. Growth of a surface layer due to the crystallization of the secondary crystalline phase PbO‐ Al 2 O 3 ‐2SiO 2 resulted in the coexistence of coarse and fine perovskite particles. The increase in the relative number of coarse‐to‐fine perovskite particles with the heating temperature/time was the major factor responsible for increased spontaneous deformation and higher Curie temperature of the perovskite phase. Substitution of barium for lead in the lead titanate phase probably occurred and is explained by the use of SiO 2 instead of B 2 O 3 as the glass former in the present study.