Abstract:Rare earth oxides Re2O3 (Re=Pr, Nd) doped SrTiO3 ceramics with the formula of [Re0.02Sr0.97(VSr)0.01]TiO3 (Re0.02Sr0.97TiO3: Re-STO) were prepared by a solid state reaction method. The X-ray diffraction (XRD) results indicate that Re-STO ceramics have a single cubic perovskite structure which is similar to that of pure SrTiO3. Scanning electron microscopy (SEM) analysis shows inhomogeneous grain size distribution in Re-STO ceramics with big grains of about 10 μm and small ones of about 1 μm, and the small grains normally exist in grain boundaries and/or triangle grain boundaries among big grains. The dielectric properties of Re-STO ceramics were measured by HP4294 precision impedance analyzer, JJC9906-A breakdown strength testing instrument and FMRL bias voltage testing system, and the energy storage characteristics was evaluated. The results show that the relative dielectric constants of Re-STO ceramics (Pr-STO: εr=1860; Nd-STO: εr=1670), prepared at the optimized sintering temperature of 1350 oC, increase by more than 5 times than that of pure STO ceramics (εr=300 kHz), while the dielectric loss of Re-STO ceramics still remains lower than 0.03 (1 kHz). The breakdown strength Eb of Re-STO ceramics is higher than 15 kV/mm. Under the bias voltage testing conditions used in this study, the εr of Re-STO ceramics changes within ±12%, and the relationship between energy storage density and bias voltage is in good line with quadratic parabola function. Therefore, Re-STO ceramics can be treated as linear dielectrics, which should be very promising for medium/high voltage solid state energy storage applications. Meanwhile, the relationship between the phase structure, microstructure, possible defect structure and the dielectric properties, energy storage characteristics of Re-STO ceramics were also discussed.