Dielectric properties of ferroelectric ceramic Bi₆Ti₃Fe_2-хNi_хO₁₈ with the Aurivillius phase structure

Abstract

A family of new solid solutions Bi₆Ti₃Fe_2-xNi_хO₁₈ by conventional ceramic technology where x = 0; 0.1; 0.2; 0.3; and 0.4 was obtained. The temperature dependence of the dielectric constant at a frequency of 1 kHz in the temperature range from 25 to 400 °C was studied. A pronounced maximum was observed that is associated with a structural phase transition. A deviation from the Curie-Weiss law near the phase transition point was found, due to the diffusion of the transition and is explained by the Smolensky-Isupov model. Based on this model, the concentration dependences of the diffuseness parameter and the volume of the critical nucleus of the polar phase were determined.

Keywords:

• Ferroelectric ceramics
• phase transition
• Känzig volume
• temperature coefficient of permittivity
• Aurivillius phase