EFFECT OF Zno-TeO2 GLASS DOPING ON STRUCTURAL AND DIELECTRIC PROPERTIES OF BiFeO3 PREPARED BY SOLID STATE METHOD

Abstract

Impurity phase formation and large leakage current values have been major problems for technological applications of multiferroic BiFeO₃ compounds. In this study, excess amount of Bi was added to compensate the loss of Bi in the samples during sintering. Zinc tellurite (ZT) glass added BiFeO₃ samples was prepared by conventional solid state method with the composition of (1-x)BiFeO₃ - (x)ZnO-TeO₂ (x = 0, 0.03, 0.05, 0.10) samples. XRD analysis showed that the addition of 2 mol% excess amount of Bi to BiFeO₃ has suppressed the formation of secondary phases such as Bi₂Fe₄O₉ during sintering. No secondary phase peaks were observed in ZT glass added samples. SEM images showed that the grain morphology changed from angular faceted in BiFeO₃(with 2 mol% excess) to rounded grains in ZT glass was added samples. Dielectric properties of samples were measured in the frequency range of 100 Hz to 1 MHz at room temperature. The dielectric constant of ZT glass added BiFeO₃ has improved due to increased grain boundary resistance and oxygen vacancies as a result of ZT glass addition. The insulating ZT glass reduced grain to grain contact at the grain boundary resulting in reduced dielectric loss at higher ZT glass addition.