High-temperature impedance, modulus spectroscopy and conductivity study of Nd modified barium stannate titanate electroceramics

Abstract

Polycrystalline (Nd_2x/3Ba_1-x)(Ti_0.95Sn_0.05)O₃ namely NBTS electroceramics with different concentrations of Nd doping i.e., x = 0.00-1.5 mol % are prepared by conventional solid-state reaction method. Structural characterization reveals that NBTS ceramics are single phase tetragonal structure that belongs to P4mm space group. Highly dense microstructures are observed in FE-SEM micrographs. Impedance, modulus, and conductivity studies are done at 350–500 ^°C. Typical negative temperature coefficient resistance (NTCR) behavior confirms in the Nyquist study. The detailed study of Nyquist plots suggests that grain resistance (R_g) and grain boundary resistance (R_gb) are strongly affected by the applied temperature and Nd-doping in the NBTS ceramics. Imaginary part of electrical impedance (Z″) and modulus (M″) as a function of frequency confirms relaxation in NBTS ceramics at high temperatures. The activation energy observed in imaginary impedance and modulus spectra may be attributed to oxygen vacancies (OVs). The scaling behavior of impedance and modulus spectra suggest that temperature dependence of relaxation processes exists in the sample. These studies suggest that NBTS ceramics are potential candidates for future power electronics applications at high temperatures.