Influence of current density on microstructure and dielectric properties during the flash sintering of strontium titanate ceramics

•Dense SrTiO3 ceramics with small grains and outstanding dielectric properties were prepared by flash sintering at 1145 °C.•A new change rule was found in the current density dependence of density for SrTiO3 ceramics.•The avalanche multiplier model was innovatively introduced to understand the origin of flash sintering.