A comparative study on the effect of Cr3+, Fe3+and Ni2+substitution on the dielectric, ferroelectric and electrocaloric response of BST ceramics

A comparative study on the influence of different 3d transition metal ions (Cr3+, Fe3+ and Ni2+) on the structural, dielectric, ferroelectric and electrocaloric response of BST ceramics is reported in the present work. Conventional solid-state reaction method was adopted for preparing the samples. A pure perovskite phase with tetragonal structure was confirmed by X-ray diffraction (XRD) analysis. Tetragonality was found to be decreased with the substitution of transition metal ions except in Cr3+ substituted sample. The dielectric behavior was investigated as a function of temperature (30 degrees C-150 degrees C) at different frequencies. Dielectric constant (e) data was fitted with Power Law above Tc and diffused phase behavior was observed in the samples. P-E loops were recorded at different applied electric fields and temperatures. Improvement in ferroelectric properties (Pr = 10.56 mu C/cm2, Ec = 2.40 kV/cm and Pr/Pmax = 0.53) was observed for Cr-substituted sample. Indirect method based on Maxwell's entropy-polarization relationship was employed to evaluate the electrocaloric effect (ECE) for all the samples. The value of ATmax was found to be maximum for (1.113K) for Cr substituted samples. The results show that Cr substituted BST are suitable for use in capacitor, memory devices and new generation solid-state cooling devices.