Cerium doped strontium titanate with stable high permittivity and low dielectric loss

High permittivity materials continue to arouse considerable interest due to their applications in the field of high performance capacitors. However it is still a challenge to make material both with stable high permittivity and low dielectric loss. Here, the Sr_1-3x/2Ce_xTiO₃ (SCT) ceramics are synthesized via solid-state reaction process and sintering in air. The sample (x = 0.01) exhibits a high permittivity of ∼7000 and low dielectric loss of ∼0.007 at room temperature and 1 kHz. Moreover, the dielectric properties are stable over a very broad temperature and frequency range. Further investigations reveal that the high permittivity is related to the defect chemistry caused by the trace Ce ions doping. The Ti³⁺ ions substitute the Ti⁴⁺ ions lead to the Ti-O octahedral off-center, which make a certain contribution to improve the permittivity. The low dielectric loss is owing to the fact that the defects are more likely to be in the form of defect clusters in the Ce doped SrTiO₃ monophase solid solutions. The appropriate defect chemistry design suppresses the dielectric loss relaxation peak of Sr_1-xCe_xTiO₃ (x = 0.01) caused by the motion of oxygen vacancies.