Dielectric properties and microstructure of magnesium-doped Ba1+k(Ti1−xCax)O3−x+k ceramics

The dielectric properties and microstructure of magnesium-doped Ba1+k(Ti1−xCax)O3−x+k ceramics have been investigated. When Ba1+k(Ti1−xCax)O3−x+k ceramics, 0≤x≤0.02, 0≤k≤0.01, sintered in pure nitrogen, it behaves as undoped barium titanate. In this study, microstructure, electrical resistivity and dielectric characteristics of magnesium-doped Ba1+k(Ti1−xCax)O3−x+k ceramics with various k and x value and magnesium concentration are studied systematically. Moreover, the effects of Ba/Ti ratio on microstructure and dielectric properties were studied. The results show that Magnesium-doped Ba1+k(Ti1−xCax)O3−x+k was more difficult to sinter than ceramic Ba1+k(Ti1−xCax)O3−x+k. Ca and Mg co-doped BaTiO3 has the poorest electrical resistivity properties compared to Ca- or Mg-doped BaTiO3. When temperature is higher than 100 °C, the curve of temperature dependence of dielectric loss warps upwards markedly, which is caused by migration of oxygen vacancies. Ba/Ti ratio had an important impact on the Curie temperature.