Voltage breakdown strength and energy density of ceramic SrTiO₃ at cryogenic temperatures from 295 K to 77 K

The low-temperature dependence of the DC dielectric breakdown strength (EBD) and the energy storage density (W) of capacitors, fabricated from high purity polycrystalline strontium titanate, were investigated in the temperature range from 295 K to 77 K. Test samples were constructed with a process similar to that used for multilayer ceramic capacitors (MLCCs). The permittivity, loss tangent, leakage current, and breakdown strength were measured as a function of temperature and voltage. Weibull statistical analysis was used to quantify breakdown distributions. Despite electric-field suppression of permittivity, breakdown strength increased significantly with decreasing temperatures, leading to enhanced energy density. The breakdown field increased from approximately 440 kV/cm at 295 K to 770 kV/cm at 77 K, while the corresponding energy density rose from 2.1 J/cm³ to 4.9 J/cm³, respectively. Possible mechanisms for the increase in breakdown voltage with decreasing temperatures are discussed.