Optimization of Sintering Conditions to Enhance the Dielectric Performance of Gd(3+) and Ho(3+) Codoped BaTiO(3) Ceramics

BaTiO(3) dielectric capacitors, one of the important energy storage devices, play critical roles in storing electricity from renewable energies of water, wind, solar, etc. The synthesis of BaTiO(3) ceramics with weak temperature dependence and a high dielectric constant at room temperature (ε(RT)′) is an urgent problem to meet the miniaturization and large capacity of dielectric capacitors. Doping rare earth elements into BaTiO(3) can solve this problem, but it is still challenging. In this work, we adopt a synergistic strategy of increasing ε(RT)′ and improving the temperature stability by codoping Gd(3+) and Ho(3+), respectively, to address this challenge. By carefully adjusting the synthesis conditions in the solid-state reaction, codoping 7% Gd(3+) and 7% Ho(3+) in BaTiO(3) (BGTH7) ceramics were synthesized. The temperature-dependent dielectric constant reveals that the obtained optimal BGTH7 ceramic satisfies the X7U specification and displays a stable ε′ in the temperature range of −55~125 °C. The optimal BGTH7 ceramic after sintering at 1400 °C for 6 h exhibits a high dielectric constant of 5475 and low dielectric loss (tan δ) of 0.0176, hitherto exhibiting the best performance in X7U ceramics. The findings in this work are conducive to the miniaturization and stabilization of dielectric energy storage devices.