Giant dielectric and low voltage varistor behaviors of Ba-doped Bi1/2Na1/2Cu3Ti4O12 ceramics

Bi1/2−xNa1/2−xBa2xCu3Ti4O12 (x = 0, 0.025, 0.05, 0.075) polycrystalline ceramics are prepared by a modified Pechini method. Effect of Ba doping on the dielectric and nonlinear electrical behaviors are investigated in detail. All the samples exhibit giant dielectric effect and nonlinear electrical behavior. Compared with Bi1/2Na1/2Cu3Ti4O12 ceramics, the permittivity drops down and the nonlinear electrical behavior shifts to low voltage area by Ba doping. The permittivity reduces from 20,004 to 7,006 at 1 kHz. The breakdown voltage and nonlinear coefficient values decrease to 10.8 V/mm and 1.5, respectively. Additionally, the electrostatic barrier height drops down to 0.66 eV. Giant dielectric response and nonlinear electrical behavior can be interpreted in terms of internal barrier layer capacitors model. These results imply that Ba substitution can adjust the dielectric and nonlinear electrical behaviors of Bi1/2Na1/2Cu3Ti4O12 ceramics, which is a promising candidate for low voltage varistor materials.