Effect of V₂O₅–TeO₂ Glass Addition on Dielectric Properties of CaCu₃Ti₄O₁₂ Ceramics Prepared by Solid State Method

Abstract

CaCu₃Ti₄O₁₂ (CCTO) is well known to have colossal dielectric constant in the range of 10⁵. However, CCTO has considerably high dielectric loss values (tanδ > 0.1) at room temperature and 1 kHz. In this work, addition of glass to CCTO was suggested in order to improve its dielectric properties. The effect of V₂O₅–TeO₂ (VT) glass addition on microstructure and dielectric properties of CCTO ceramics were investigated. Dielectric measurements were carried out for (1 − x) CCTO-(x) V₂O₅–TeO₂ (x = 0, 0.03, 0.05, 0.10) samples in the frequency range of 10²–10⁶ Hz using impedance spectrometer. Electron micrographs showed that low melting VT glass addition facilitated the grain growth of CCTO. As VT glass amount increased, dielectric constant decreased. The drop, though within reasonable values (~10⁵), may related to the presence of grain boundary glassy phase which itself has low dielectric constant. However, the dielectric loss of the composite has decreased after VT glass addition. The low melting V₂O₅–TeO₂ glass aided in liquid phase sintering and improved the grain boundary resistance which resulted in decreased leakage currents.