Study of Lead Titanate Based Glass Ceramics with Addition of BaO

Glass samples with composition of (50-X) PbO-X BaO-25 TiO2-25B(2)O(3) (where X = 0, 5, 10 and 15 mol%) were prepared using conventional quenching technique. The amorphous nature of glass samples were confirmed by XRD. The glass transition temperature, T-g and crystallization temperature T-c were determined from the DTA. It has been observed that the addition of BaO enhances the T-g and reduces the T-c. These glass samples were converted to glass ceramics by following two stage heat treatment schedule. The glass ceramic samples were characterized by XRD, SEM and dielectric constant measurements. The dielectric constant for all the glass ceramic samples was observed to be higher than that of corresponding glass samples. Further, with addition of BaO the dielectric constant for glass ceramic samples increases up to 10 mol% of BaO and beyond this concentration it decreases. The XRD results revealed the formation of ferroelectric Lead Titanate as a major crystalline phase in the glass ceramics. This is supported by the SEM results which show rounded crystallites of lead titanate. This explains the enhancement in the dielectric constant. The addition of BaO to the glass contributes to the formation of BaB2O4 and Barium-Titanium-Borate (BTB) phases. Additional phases observed in these glasses include PbB2O4 and PbB2O7. This has been supported by SEM results indicating needle-like crystals in glass ceramic samples containing higher concentration of BaO. The observed hysteresis (P vs. E) loop at room temperature confirmed the ferroelectric nature of these glass ceramics.