Effects of PbO and SrO contents on crystallization and dielectric properties of PbO–SrO–Na2O–Nb2O5–SiO2 glass–ceramics system

PbO–SrO–Na2O–Nb2O5–SiO2 glass–ceramics were prepared via roll-quenching followed by controlled crystallization from 700 °C to 900 °C. The effects of PbO and SrO contents on crystallization and dielectric properties were investigated. The results show that Pb2Nb2O7, Sr2Nb2O7 and their solid solutions crystallize at 700 °C, NaNbO3 is the primary phase at 800 °C, Pb2Nb2O7 disappears and PbNb2O6 forms at 900 °C. The dielectric properties of the glass–ceramics formed through controlled crystallization has a strong dependence on the phase compositions that were developed during heat treatment. The highest dielectric constants (∼600) are found in samples with 6.0 mol% SrO annealed at 900 °C for 3 h. The dielectric–temperature characteristics of the samples show stability over the range from −60 °C to 180 °C, except the sample without SrO heated at 900 °C.