The effect of Sm and Nb on impedance spectroscopy and high frequency modulus, complex modulus, conductivity studies of BaTiO3-Li0.5Fe2.5O4 ceramics.

The Sm and Nb substituted 90% of BaTiO 3 -10% of Li 0.5 Fe 2.5 O 4 are synthesized using solid state preparation method. The X-ray diffraction, the frequency dependent of impedance, complex impedance at different temperatures, Nyquist plots at different temperatures, the variation of modulus and conductivity with high frequency region between 1 MHz and 3.2 GHz at 30 °C of composites were studied. The impedance of composites decreases steeply beyond 100 kHz and impedance value of 90BLF increases with increase in the concentration of Sm and Nb in BLF. The real and complex impedance changes with frequency. As temperature increases the real part of impedance of composites decreases and beyond certain frequencies, the impedance decreases sharply and merge at 10 MHz. As temperature increases the complex impedance Z″ max peaks shifted towards higher frequency i.e peak frequency f max increases with increase in temperature. The impedance curve of composites identified by exhibits single semi circle represents type of relaxation described by Debye model. The relaxation time (τ) of composites decreases with the increase in temperature. Beyond frequency 3 GHz, the modulus of composites exhibits complex behavior and the complex modulus (M″) peaks exhibits jumping behavior could be explained by Debye-type relaxation. The conductivity peak of 90BLF composites are shifted towards higher frequency with the increase in concentration of Sm and Nb in it due to the substitution of Nb and Sm in 90BLF. • The complex impedance (Z″) peaks shifted towards higher frequency with increasing temperature. • The radius of the semicircles decreases with increasing temperature due to temperature dependence of relaxation. • The relaxation time (τ) of composites decreases with increase in temperature. • The activation energy of composites increases with increase Sm and Nb. • The complex modulus (M″) peaks of all the composites exhibits jumping behavior. [ABSTRACT FROM AUTHOR]