Effect of Co-Doping Holmium and Cerium on Relaxor Characteristics of BaTiO ₃ -based Ceramics

Barium titanate (BaTiO 3 , BT) is widely used in a multitude of dielectric applications, including capacitors, sensors, and energy storage devices. Co-doping in BT has a dramatic influence on the electrical properties which can be attributed to the crossover from the ferroelectric state to the relaxor state. The relaxor state is triggered by structural disorder, leading to localized fields that interfere with long-range polar order for various cation substitutions and quantities. Here, we investigate the effect of co-doping in BT with rare-earth elements (Ho and Ce) using solid-state synthesis to establish the dopant-property relationship. Structural characterization via X-ray diffraction (XRD) confirmed that all co-doped compositions have a phase pure, pseudo-cubic perovskite phase. Meanwhile, temperature-dependent dielectric measurements showed that the system exhibited a diffuse phase transition along with a high dielectric constant [Formula: see text] and a low dielectric loss (tan [Formula: see text]0.015) at the Curie temperature [Formula: see text]. With an increase in dopant concentration, a maximum diffusivity (± 15% of permittivity consistent between 44-77[Formula: see text]C) was observed at a composition with 5 mol% Ho and 5 mol% Ce in BT. The compounded effect of rare-earth element substitution along introduction with Ti vacancies causes a transition to relaxor behavior along with high dielectric constant, comparable to pure BT. This result represents a significant improvement as compared to prior studies on BT or RE-doped-BT ceramics which show that the compositional modifications to induce relaxor behavior typically suppress the dielectric constant.