DTA observation of phase transformation from cubic to tetragonal PbTiO3 inquaternary glass system: PbO-B2O3-TiO2-BaO

Lead titanate, PbTiO3, transforms from paraelectric (cubic) to ferroelectri c (tetragonal) at about 490 degrees C on cooling: If was reported that this phase transformation in a lead titanate glass or gel could not be observed in DTA until the sample was heated to a certain temperature. The origin of the appearance of this ferroelectric anomaly in DTA was investigated for t he quaternary (PbO-B2O3-TiO2-BaO) lead titanate glass and glass ceramics Th e temperature where the ferroelectric anomaly appears on cooling decreased with increasing BaO content in the compositions. For as crystallised sample s the ferroelectric anomaly was not observed on heating but on cooling, whi le for powder samples chemically leached after crystallisation, both an end othermic and exothermic peak due to phase transformation were observed. Thi s fact suggests that the appearance of the ferroelectric anomaly in DTA lar gely depends upon glassy phases surrounding individual PbTiO3 crystals.