Structural, dielectric and electrocaloric properties of (Ba0.85Ca0.15)(Ti0.9Zr0.1-xSnx)O3 ceramics elaborated by sol-gel method

TL;DR

This study explores how doping with Sn affects the structural, dielectric, and electrocaloric properties of BaCaTiZrSnO ceramics prepared via sol-gel, revealing phase changes, dielectric relaxation, and notable electrocaloric responses.

Contribution

It provides new insights into the effects of Sn doping on the phase structure and electrocaloric properties of BaCaTiZrSnO ceramics, which were not previously characterized.

Findings

Doped ceramics exhibit only tetragonal structure, while undoped shows coexistence of tetragonal and orthorhombic phases.

Sn doping causes a decrease in Curie temperature and reveals dielectric relaxation related to oxygen vacancy hopping.

Electrocaloric responsivity peaks at 0.225×10^-6 K·m/V for x=0.04 Sn doping.

Abstract

Ferroelectric ceramics (Ba0.85Ca0.15)(Ti0.9Zr0.1-xSnx)O3 (x=0.00, 0.02, 0.04, 0.06) were prepared by a sol-gel method. Structural investigation revealed the co-existence of tetragonal (P4mm) and orthorhombic (Pmm2) symmetries at room temperature for the undoped ceramic, while only a tetragonal structure (P4mm) was observed for the doped ceramics. Dielectric measurements indicate a dielectric relaxation process at high temperatures which is essentially related to the hopping of oxygen vacancies. Furthermore, a down shifting of the Curie temperature (TC) with increasing Sn4+ doping rate has been revealed. The temperature profiles of the Raman spectra unveiled the existence of polar nanoregions (PNRs) above the Curie temperature in all ceramics. The ferroelectric properties were found to be related to the microstructure. Electrocaloric effect was investigated in this system that revealed an electrocaloric responsivity of 0.225 10-6 K m/V for the composition with x = 0.04 Sn doping, where other remarkable physical properties were also observed.