Structure and high temperature dielectric properties of Dy and Al co-doped CaTiSiO₅ ceramics

The CaTiSiO₅-based ceramics show promise as dielectric materials for high-temperature MLCC due to their excellent temperature stability which is expected to be improved by co-doping at the A/B sites. In this study, the Dy and Al co-doped CaTiSiO₅ ceramics (Ca_1−xDy_xTi_1−xAl_xSiO₅, x = 0, 0.005, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08) were fabricated by the conventional solid-state method. The effects of Dy and Al co-doping on the phase structures, dielectric properties and impedance characteristics, were investigated in detail. CaTiSiO₅-based ceramics transformed to the paraelectric phase and achieved excellent temperature stability of permittivity by Dy and Al doping, which results from the long-range disorder in the arrangement of Ti displacements within the octahedral chain. Components with x = 0.01 showed linear dielectric response under the electric field. It obtained a high and stable dielectric constant in a wide temperature range (ε_r = 52, TCC ≤ ± 180 ppm/°C over the temperature range from − 55 to 300 °C), low loss (tanδ < 0.07), high breakdown strength (∼ 516 kV/cm) and high DC resistance (ρ = 3.8 × 10¹⁰ Ω cm at 300 °C).