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.