Mechanism of Ca-Ba diffusion in lead-free (Ba,Ca)TiO3 piezoelectrics

Abstract

AbstractThe reaction mechanism of BaCO3+CaCO3+TiO2 by solid state methods has been studied in this work using thermal analysis (DSC-TG) from 500 to 1500 °C and in situ X-ray diffraction (XRD) from room temperature to 800 °C. In the mixed powders, the CaO is firstly formed followed by presence of an intermediate Ba2TiO4 phase and finally the formation of CaTiO3, BaTiO3 and/or (Ba,Ca)TiO3, where the presence of CaO or CaTiO3 (CT) has slowed down the formation of BaTiO3 (BT). Raman microscopy of a BT-CT diffusion couple has shown that Ca2+ firstly diffuses into the BT grain boundaries and then into the BT core.