Dielectric and impedance spectroscopic studies of (Sr_1−xPb_x)TiO₂ glass ceramics with addition of Nb₂O₅

摘要

Glasses were made by melt-quench method in the system [(Sr_1−x Pb _x )O·TiO₂]-[2SiO₂·B₂O₃]-5[K₂O-BaO] (0·0 ≤ x ≤ 0·4) with addition of 1 mol% Nb₂O₅. Perovskite strontium lead titanate in solid solution phase has been crystallized in borosilicate glassy matrix with suitable choice of composition and heat treatment schedule. Addition of 1 mol% of Nb₂O₅ enhances the crystallization of lead strontium titanate phase in the glassy matrix. Scanning electron microscopy (SEM) is performed to study the surface morphology of the crystallites and crystalline interface to the glass. Dielectric properties of these glass ceramics were studied by measuring capacitance and dissipation factor as a function of temperature at a few selected frequencies. Nb₂O₅ doped strontium lead titanate glass ceramic shows a high value of dielectric constant. It is of the order of 10,000 while the dielectric constant of undoped glass ceramic sample is of the order of 500. Complex impedance and modulus spectroscopic techniques were used to find out the contributions of polarization of crystallites and glass crystal interfaces to the resulting dielectric behaviour.