Dielectric and ferroelectric properties of Nb-doped Ba_0.8Sr_0.2TiO₃ ceramics

Ferroelectric and dielectric properties were investigated for Ba_0.8Sr_0.2Ti_(1−5/4x)Nb _x O₃ ceramics with different Nb₂O₅ concentrations. The relations between the ceramic structures and those properties were discussed. The Ba_0.8Sr_0.2TiO₃ doping with 0.01mol% Nb₂O₅ appears to have a strong ferroelectric effect and better dielectric properties. The max permittivity (ɛ _max) is up to 7,521.3 and Ba_0.8Sr_0.2Ti_(1−5/4x)Nb _x O₃ ceramics has higher permittivity even at room temperature. The permittivity presents broadened curves at large temperature ranges, which suggests a non Curie–Weiss behavior near the transition temperature. The diffuse phase transition coefficient (δ) for Ba_0.8Sr_0.2Ti_(1−5/4x)Nb _x O₃ doping with 0.01mol% Nb₂O₅ reaches 0.098, and its P–E loop expresses a diffusing curve. The remanent polarization (2P _r) and coercive field are 31.3 μC/cm² and 10 kV/cm, respectively. The P–E loop presents a diffusing curve, which is relative to the relaxor characteristic.