Effects of PbO and SrO contents on crystallization and dielectric properties of PbO-SrO-Na_2O-Nb_2O_5-SiO_2 glass-ceramics system

摘要

PbO-SrO-Na_2O-Nb_2O_5-SiO_2 glass-ceramics were prepared via roll-quenching followed by controlled crystallization from 700 deg C to 900 deg C. The effects of PbO and SrO contents on crystallization and dielectric properties were investigated. The results show that Pb_2Nb_2O_7, Sr_2Nb_2O_7 and their solid solutions crystallize at 700 deg C, NaNbO_3 is the primary phase at 800 deg C, Pb_2Nb_2O_7 disappears and PbNb_2O_6 forms at 900 deg 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 (approx 600) are found in samples with 6.0 mol percent SrO annealed at 900 deg C for 3 h. The dielectric-temperature characteristics of the samples show stability over the range from -60 deg C to 180 deg C, except the sample without SrO heated at 900 deg C.