Dielectric properties and relaxation behaviors of Ba doped Sr0.97Sm0.02TiO3 ceramics in different sintering atmospheres

The BaxSr0.97−xSm0.02TiO3 (x=0-0.4) ceramics in different sintering atmosphere were prepared by conventional solid-state reaction methods. The effect of different atmosphere on the dielectric properties of BaxSr0.97−xSm0.02TiO3 ceramics was investigated. The giant permittivity was obtained for BaxSr0.97−xSm0.02TiO3 ceramics sintered in nitrogen especially for x=0.2, which exhibited a weak temperature- and frequency- dependent giant permittivity (>104) as well as a low dielectric loss (mostly <0.05) over a broad temperature range from 20 to 300 °C. Based on the relaxation behaviors, XPS Spectrum and complex- impedance analysis of ceramics in different sintering atmosphere, the giant permittivity and low dielectric loss were due to the existence of the giant defect dipoles [Ti4+·e -Vo..- e·Ti4+] generated by the fully ionized oxygen vacancies and Ti3+ ions, while the defect dipoles (VSr,,−Vo..) and interfacial polarization caused the dielectric relaxation of the ceramics sintered in air or O2.