Dielectric, modulus and impedance analysis of (Ba_0.9Bi_0.1)(Ti_0.9Al_0.1)O₃ ceramics

Polycrystalline (Ba_0.9Bi_0.1)(Ti_0.9Al_0.1)O₃ (BBTA) ceramic is synthesized by solid state reaction method. XRD studies confirm the formation of single phase composition. Detailed studies of dielectric and impedance properties of the material in the wide range of frequency (20–2 MHz) and temperature (225–400 °C) shows that dielectric properties are strongly temperature and frequency dependent. The circle centers of Cole–Cole plots between ε′ and ε″ is located on the ε′ axis, confirming the monodispersive nature of the relaxation processes for hopping electrons. The plots of Z″ and M″ are disperated with increase in frequency at different temperature, which proves the dielectric relaxation. The value of non-exponential parameter β can be determined by the full width-at-half-maximum of M″/M″ _max spectrum (β = 1.14), indicating that the relaxation process for the sample is Debye-type relaxation phenomena in agreement with the observation from complex permittivity spectrum. The ac conductivity can be explained by the non-overlapping small polaron tunneling model.