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

The dielectric properties and microstructure of magnesium-doped Ba 1+k (Ti 1-x Ca x )O 3-x+k ceramics have been investigated. When Ba 1+k (Ti 1-x Ca x )O 3-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 ofmagnesium-doped Ba 1+k (Ti 1-x Ca x )O 3-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 Ba 1+k (Ti 1-x Ca x )O 3-1+k was more difficult to sinter than ceramic Ba 1+k (Ti 1-x Ca x )O 3-x+k . Ca and Mg co-doped BaTiO 3 has the poorest electrical resistivity properties compared to Ca- or Mg-doped BaTiO 3 . 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.