Effects of Al2O3 on the piezoelectric properties of Pb(Mn1/3Nb2/3)O3-PbZrO3-PbTiO3 ceramics

Piezoelectric properties of Al2O3-doped Pb(Mn1/3Nb2/3)O3-PbZrO3-PbTiO3 ceramics were investigated. The constituent phases, microstructure, electromechanical coupling factor, dielectric constant, piezoelectric charge and voltage constants were analyzed. Diffraction peaks for (002) and (200) planes were identified by X-ray diffractometer for all the specimens doped with Al2O3. The highest sintered density of 7.8 g/cm3 was obtained for 0.2 wt% Al2O3-doped specimen. Grain size increased by doping Al2O3 up to 0.3 wt%, and it decreased by more doping. Electromechanical coupling factor, dielectric constant, piezoelectric charge and voltage constants increased by doping Al2O3 up to 0.2 wt%, and it decreased by more doping. This might result from the formation of oxygen vacancies due to defects in O2 − ion sites and the substitution of Al3+ ions.