Piezoelectric properties of BZT-BCT ceramics obtained by mechanosynthesis and their dependence on processing parameters

Abstract

High purity phases of x(BaZr0.2Ti0.8O3) - (1-x)(Ba0.7Ca0.3TiO3) with different stoichiometry were obtained by mechanosynthesis process. Stoichiometry values were selected to achieve the presence of morphotropic phase boundaries (MPBs). The phase formation was monitored by X-ray diffraction, showing fully reaction of the oxides used as precursors after a milling time of 120 minutes. Only a small quantity of BaCO3 was detected, which was eliminated by heating the powder at 900 ºC/1h before the sintering process. The size of crystal domains and cell parameters were characterized by X-ray diffraction using Rietveld refinement. Additionally, microstructural features were analyzed by scanning and transmission electron microscopy. The ceramic powders were consolidated by uniaxial pressing and conventionally sintered in a furnace and by hot pressing at temperatures ranging from 1400 to 1500 °C. The dependence of the piezoelectric and dielectric properties on the sintering temperature and pre-heating treatment of the powders was studied. Piezoelectric coefficient (d33) was measured for different poling conditions and piezo response force microscopy (PFM) was also used to characterize the local piezoelectric behavior of the synthesized materials.