Chemical engineering at morphotropic phase boundary: Interplay with thermally stabilized ultra-high energy storage and electrocaloric response

We have performed systematic investigations on (Ba0·85Ca0.15)-(Ti0·90Zr0.10)O3 [BCTZ] morphotropic phase boundary [MPB] composition co-doped with Mg and Nb [MN]. X-ray diffraction patterns revealed that the synthesized samples crystallized with perovskite phase. Surface morphology, assessed through scanning electron microscopy, emphasizes that the grain size decreases with MN content. Modified Curie-Weiss analysis suggests the relaxor type characteristics of BCTZ-xMN (x = 0.0, 0.025, and 0.05) samples. Recoverable energy density (Wrec) attains maximum value near the ordering temperature. Maximum value of Wrec is found to be ∼54, 77 and 50 mJ/cm3 for x = 0.0, 0.025 and 0.05, respectively, which is an indication of the additional promising features of MPB composition BCTZ-0.025 MN towards energy storage operations. Further, we have calculated maximum entropy change involved in tetragonal to cubic phase transition, at electric field of 16 kV/cm, to be (ΔSmax) ∼ 0.70, 0.75 and 0.22 Jkg−1K−1, corresponding to x = 0.0, 0.025 and 0.05 composition, respectively.