Structural and modulus spectroscopy studies of Bi0.5(Na0.8K0.2)0.5TiO3 nano-polycrystalline ceramic

Abstract

Nano-polycrystalline Bi0.5(Na1−xKx)0.5TiO3 ceramic with x\u2009=\u20090.20 (BNKT-2.0) was synthesized by using the solid-state mixed oxide method. We have taken the stoichiometric ratios using the formula 0.175Na2CO3\u2009+\u20090.25Bi2O3\u2009+\u20090.05K2CO3\u2009+\u2009TiO2\u2009→\u2009Bi0.5 (Na0.8K0.2)0.5TiO3\u2009+\u20090.25CO2. Densified BNKT-2.0 ceramic was obtained at the sintering temperature of 1163 °C for 2.30 h. The influence of K+ ion substitution in BNT ceramic on structural and modulus properties was examined. XRD studies revealed a single-phase rhombohedral structure of the material with an average crystallite size of 56 nm. SEM analysis indicated polycrystalline spherical grains with the size of 1.37 μm. Modulus spectroscopy analysis showed that the continuous dispersion exhibited with an increase in frequency indicating long-range mobility of charge carriers. The activation energy of BNKT was estimated to be 0.56 eV. The non-Debye type relaxation process is observed in the sample; it is due to the hopping of mobile charges between oxygen vacancies at high temperatures. The scaling behavior of the sample was studied by plotting M /M max Vs log10 (f/fmax) at various temperatures. These results specify that Bi0.5(Na0.8K0.2)0.5TiO3 ceramic would be a promising lead-free material for active electrical devices like supercapacitors, thermistors, and transducers.