The Influence of the Firing Temperatures on the Phase Evolution, Microstructure, Dielectric and Strain Responses of BCTS Ceramics Prepared by the Solid State Combustion Technique

Abstract

© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. In this report, the influence of the firing temperatures on the phase evolution, microstructure, dielectric and strain responses of (Ba0.945Ca0.055)(Ti0.91Sn0.09)O3(BCTS) lead-free piezoelectric ceramics is investigated. BCTS ceramics are prepared with the solid state combustion technique with glycine as the fuel. Pure BCTS powders, with a perovskite structure, are obtained by calcining at 1150°C for 2h. The particle morphology of the BCTS powders exhibits a rounded shape and large agglomerated forms in all samples. The average particle size increases from 158 to 223nm when the calcination temperature is increased from 1050 to 1250°C. The XRD results of the sintered samples show they all have a single perovskite structure. The Rietveld refinement analysis indicates that the BCTS ceramics sintered at 1400°C have the orthorhombic (O), tetragonal (T), and rhombohedral (R) phases coexisting while the O+T phases coexist in the other samples. The average grain size, density, dielectric constant (at Tc), %strain, and d33* increase when the sintering temperature is increased up to 1400°C and then, reduced in values. At the optimum sintering temperature (1400°C), BCTS ceramic show multi phases (O+T+R), good crystalline morphology, the highest density (98%), an excellent dielectric constant (ε(lunate)c≅16252), and a good d33* value (866pm/V).