Defect engineering in rare-earth-doped SrTiO3 ceramics: Route to colossal capacitance material up to X9R capacitor standard

With the advent of the electronic information era, capacitors have become a hot research topic due to their economic and strategic significance. Such microelectronic components play an irreplaceable role in important fields such as scientific research and military industries. Therefore, there is an urgent need to develop dielectric materials capable of withstanding more demanding conditions. In this work, a defect engineering method was incorporating Tm3+ rare earth ions into strontium titanate were proposed, resulting in a colossal dielectric permittivity, low dielectric loss, and excellent frequency and temperature stability. For the sample with x=0.01, the dielectric permittivity exceeds 345,804, the dielectric loss is below 0.011, and the dielectric permittivity variation within the temperature range from -55 to 200°C is less than 15%, which meets the ELA X9R capacitor standard (X: -55 °C, 9: +200 °C, R: Δεr ≤ ± 15%). The excellent performance is ascribed to the electron pinning defect dipole effect (EPDD) and internal barrier layer capacitor effect (IBLC), which is verified by XPS and impedance spectra. A deeper understanding of these mechanisms could help to reveal the origin of the colossal capacitance and thus contribute to the design of materials with colossal capacitance.