Formation of lead titanate glass-ceramics from borate glasses

Glass-ceramics containing lead titanate as a primary phase can be formed from glasses in the ternary PbO-TiO₂-B₂O ₃ and the four component PbO-BaO-TiO₂-B₂O₃ systems. Formation of lead titanate as the sole crystalline phase occurs within a relatively small compositional region in these systems. Addition of BaO to the glass does not result in the formation of solid solution (Pb,Ba)TiO₃ crystals. Barium-free PbTiO₃ forms in the four component glasses, while the BaO contributes to formation of BaB₂O₄. Other phases observed in these glasses include PbB₂O₄ and PbB₂O₇. Crystal clamping can occur in more refractory glasses, which results in a shift in the peak positions in the x-ray diffraction pattern for the lead titanate phase