Effects of Mn-Addition on the Microstructure and Ferroelectric Properties of High-Temperature CaBi₂Nb₂O₉ Ceramics

High temperature ferroelectric ceramics CaBi₂Nb₂O₉ + x wt% MnCO₃ (CBNO-x) are prepared by conventional sintering method. The microstructures and ferroelectric properties are studied. The Mn-added CBNO-based ceramics have a single Aurivillius phase structure. Nearly isotropic grains are obtained and the grains become larger with the increase of MnCO₃ addition. The Curie temperature T _c decreases slightly with the increase of MnCO₃ addition. The relative dielectric constant, dielectric loss, and the P-E hysteresis loop measurements indicate that Mn ions creates "soft" and "hard" doping effects simultaneously. Superior polarization performance (2P _r of 3.0 μC/cm² and 2E _c of 40.2 kV/cm) is obtained for the CaBi₂Nb₂O₉-0.375 wt% MnCO₃ ceramics.