Enhanced energy storage properties of dysprosium doped strontium titanate ceramics

Dysprosium doped strontium titanate ceramics of formula DyxSr1−1.5xTiO3 (Dy-STO), where x=0, 0.01, 0.02, 0.03, and 0.04, were prepared by solid state reaction route. The effect of dysprosium doping amount on structure and dielectric properties of Dy-STO ceramics was investigated. All ceramics are pure cubic perovskite structure, and the lattice parameter decreases with dysprosium doping amount. Scanning electronic microscope (SEM) results show that the grain size is ~30 μm for pure strontium titanate ceramic, while lowered to less than 10 μm after doping dysprosium. Strongly enhanced dielectric constant (εr=3200 at 1 kHz) is obtained for Dy-STO ceramics with x=0.02, i.e. over 10 times that of pure strontium titanate ceramic (εr=300 at 1 kHz). Furthermore, the εr shows very stable characteristic under 0~1.92 kV/mm applied bias electric fields. In virtue of low dielectric loss (tan δ<0.03 at 1 kHz) and high breakdown strength (Eb>14 kV/mm), the Dy-STO ceramics are very promising for high voltage capacitors with enhanced energy storage density.