Investigation on the impedance spectroscopy and electrical conduction mechanism in $\hbox {SrTi}_{1-x}\hbox {V}_{x}\hbox {O}_3$ ($x = 0.00 \le x \le 0.15$) ceramics

Abstract

In this work, vanadium doped $\hbox {SrTiO}_3$ ($\hbox {SrTi}_{1-x}\hbox {V}_x\hbox {O}_3$, $x = 0.00 \le x \le 0.15$) ceramics are prepared via solid state reaction method. All the prepared samples are characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The Rietveld refinement performed on the XRD pattern confirms the cubic crystalline structure with $Pm\overline{3}m$ space group for all the samples. The grain size significantly increases by vanadium doping. The Nyquist analysis, conductivity behavior and scaling behavior of the electrical impedance ($Z''/Z''_{max}$) and modulus ($M''/M''_{max}$) of $\hbox {SrTi}_{1-x}\hbox {V}_x\hbox {O}_3$ ceramics are investigated at different temperatures (400–$500\ ^{\circ }\hbox {C}$) over a wide range of frequency (100 Hz–5 MHz). The results of Nyquist plots reveal that the electrical behavior of $\hbox {SrTi}_{1-x}\hbox {V}_x\hbox {O}_3$ ceramics are due to the contribution of both the grain and grain boundary. The negative temperature of coefficient of resistance (NTCR) behavior is also confirmed in all the investigated samples. Modulus analysis confirms that the relaxation process occurring in all the samples are of non-Debye type. The observed relaxation frequencies follow the Arrehenius equation. Activation energies are calculated for all the samples which indicate that the phenomena of electrical transport is a thermally activated process.