Effects of sintering condition on giant dielectric and nonlinear current-voltage properties of Na1/2Y1/2Cu3Ti3.975Ta0.025O12 ceramics

Abstract

The effects of sintering conditions on the microstructure giant dielectric response and electrical properties of Na1/2Y1/2Cu3Ti3.975Ta0.025O12 (NYCTTaO) were studied. A single phase of Na1/2Y1/2Cu3Ti4O12 and a high density (>98.5%) were obtained in the sintered NYCTTaO ceramics. First杙rinciples calculations were used to study the structure of the NYCTTaO. Insulating grain boundaries (i朑Bs) and semiconducting grains (semi朑s) were studied at different temperatures using impedance and admittance spectroscopies. The conduction activation energies of the semi朑s and i朑Bs were Eg ? 0.1 and Egb ? 0.6 eV respectively. A large dielectric constant (?? ? 2.43�89 ? 104) and low loss tangent (tan? ? 0.046�021) were achieved. When the sintering temperature was increased from 1070 to 1090 ?C the mean grain size slightly increased while ?? showed the opposite tendency. Furthermore the breakdown electric field (Eb) increases significantly. As the sintering time increased from 5 to 10 h the mean grain size did not change whereas ?? and Eb increased. Variations in the dielectric response and non杔inear electrical properties were primarily described by the intrinsic (Egb) and extrinsic (segregation of Na� Cu� Ta� and O杛ich phases) properties of the i朑Bs based on the internal barrier layer capacitor effect. ? 2023 The Authors