Structure and Dielectric Properties of Re 0.02 Sr 0.97 TiO 3 ( Re = La , Sm , Gd , Er ) Ceramics for High‐Voltage Capacitor Applications

Rare–earth‐doped strontium titanate ceramics yielding the formula Re 0.02 Sr 0.97 TiO 3 ( Re – ST , Re  = La, Sm , Gd , Er ) were prepared by solid‐state reaction route. All Re – ST ceramics had single cubic perovskite structure similar to pure SrTiO 3 ( ST ). The grain size of Re – ST ceramics dramatically decreased to 1–10 μm, depending on different rare‐earth elements, as compared to ~30 μm of pure ST . The relative dielectric constant of Re – ST ceramics (ε r  = 2750–4530 at 1 kHz) showed about 10–15 times higher than that of pure ST (ε r  = 300 at 1 kHz), whereas the dielectric loss of Re – ST ceramics still remained lower than 0.03 (at 1 kHz) at room temperature. Under 0–1.63 × 10 6  V/m bias electric field testing conditions, the ε r of Re – ST ceramics at room temperature changed within 14%. The P – E results indicated that the Re – ST ceramics were linear dielectrics. Together with their relatively high breakdown strength ( E b  > 1.4 × 10 7  V/m), the Re – ST ceramics could be very promising for high‐voltage capacitor applications. Meanwhile, the temperature stability of the ε r of Re – ST ceramics was evaluated in a temperature range of −60°C–200°C.