Investigation of microstructure and dielectric properties of LaMnO3 doped BaTiO3 ceramics

Abstract

The microstructure and dielectric properties of LaMnO3 (LM) doped BaTiO3 (BT) ceramics have been investigated. By adding LM, (1–x)BT-xLM (x = 0–0.5) ceramics keep in a single-phase solid-solution state, but gradually transform from tetragonal structure to pseudocubic one, and much denser microstructure is obtained. As for dielectric properties, when x ≤ 0.1, the Curie temperature of BT-LM shifts to a lower temperature and the permittivity maximum is lowered with the increase of LM content, which are attributed to the introduction of La2O3 and the degradation of tetragonality, respectively. When x > 0.1, BT–LM presents a typical relaxation behavior. Colossal permittivity appears as x reaches 0.4, which is related to large number of giant electron-pinned defect-dipoles ( $${\text{Mn}}^{4 + } \cdot 2e - V_{\text{O}}^{ \cdot \cdot }$$ ) and existence of grain-boundary segregation. Detailed analyses show that 0.5BT–0.5LM possesses the highest permittivity maximum (41,683) and widest temperature range (– 42 to 300 °C) with permittivity larger than pure BT at 100 kHz. Therefore, 0.5BT–0.5LM can be a very promising candidate as colossal permittivity material.