Effect of fabrication routes on the microstructure, the dielectric and ferroelectric properties of the Mn-doped BaTiO3 ceramics

The effect of fabrication routes on the microstructure, the dielectric and ferroelectric properties of the Mn-doped BaTiO3 ceramics was systematically studied in the present study. It can be concluded that the ways of doping manganese into BaTiO3 matrix had a strong impact on the obtained ceramics. Doping manganese after the calcination of BaTiO3 (BT + Mn) would inhibit the grain growth and cause the hexagonal BaTiO3 when sintered at 1,400 A degrees C in the air. While doping manganese at the initial stage [BaTi(1-x)MnxO3], no hexagonal BaTiO3 is detected in the same sintering temperature. As the macroscopic properties, the dielectric properties showed permittivity diffusion with the frequency in the temperature range of -10 to 150 A degrees C only in the ceramics fabricated by the former route (BT + Mn). Moreover, the dielectric relaxation process disappeared after aging treatment only in the ceramics fabricated by the later route [BaTi(1-x)MnxO3]. The ferroelectric properties showed strong aging effect in the sample fabricated by the latter route [BaTi(1-x)MnxO3] both with fine grain and coarse grain, while the sample fabricated by the former route (BT + Mn) showed slight aging phenomenon ever after aging at room temperature for 10 days. The electrostrain also showed big difference within different samples: The recoverable electrostrain were 0.11 % (BT + Mn) and 0.21 % [BaTi(1-x)MnxO3] at the same sintering temperature of 1,320 A degrees C and aging in the room temperature for 10 days. Such results were analyzed from the viewpoint of the differences in solubility of manganese and the consequent manganese-oxygen vacancy defect dipoles in the different fabrication routes.