Dielectric Properties of Niobate Glass Ceramics of PbO-SrO-Na₂O-Nb₂O₅-SiO₂ System with Partial Substitution of K⁺ for Na⁺

Abstract

Substitution of K₂O for Na₂O content was performed for ferroelectric glass ceramics in the PbO-SrO-Na₂O-Nb₂O₅-SiO₂ system, in which a conventional melt quenching method was adopted for the parent glass production in order to investigate its effect on the crystallization process and associated dielectric properties. Phase identification combined with differential thermal analysis results show that the crystalline phase was compressed by the substitution of potassium ions. The hysteresis loop results demonstrate that by increasing the substitution of K⁺ for Na⁺, the maximal polarization was decreased while both the remanent polarization and coercive electric field increase. It is also noted that increasing the content of K⁺ could also reduce the dielectric constant of the glass ceramic system; the dielectric constant demonstrated a decrease from 775 to 299, meanwhile, the dielectric loss increased from 0.013 to 0.021 when 50 mol.% Na⁺ was replaced by K⁺. Additionally, leakage current results show that as more sodium ions are replaced by potassium ions, the leakage current increased and the resistivity decreased.