Effect of charge compensation change on the crystal structure, grain growth behavior, and dielectric properties in the La2O3-doped BaTiO3 system with MnCO3 addition

Abstract

The effect of MnCO 3 additions on crystal structure, grain growth behavior, and dielectric properties were studied in the La 2 O 3 -doped BaTiO 3 system. La 2 O 3 -doped BaTiO 3 powders were prepared by conventional solid-state reaction routes and then after the addition of MnCO 3 , the powder compacts were sintered at 1250 ℃ in air. The tetragonality (c/a) of the samples increased with the amount of up to 0.5 mol% MnCO 3 and then decreased above 0.5 mol%. The 3D grain shape became more spherical polygons with increasing amounts of MnCO 3 . The grain growth behavior changed from suppressed growth to abnormal grain growth and finally normal grain growth with increasing amounts of MnCO 3 when the powder compacts were sintered. The correlation between the grain growth behavior and the grain shape change is discussed from the perspective of two-dimensional nucleation grain growth theory. Further, the dielectric properties are discussed in terms of the crystal structure, microstructural control, and charge compensation. • Grain growth behavior and crystal structure were investigated in La-doped BaTiO 3 with added MnCO 3 . • The tetragonality changed depending on the formation of oxygen vacancies and Ti-site replacement. • The grains of the sintered samples changed to a more spherical shape with the addition of MnCO 3 . • The critical driving force for growth steadily decreased with an increasing amount of MnCO 3 . • The dielectric properties could be controlled by altering the microstructure, tetragonality, and charge compensation.