Effects of Sm₂O₃ addition on the dielectric and energy storage properties of BaTiO₃ ceramics

BaTiO₃ (BTO) is the most widely used dielectric material for capacitors. However, the use of pure BTO ceramics in capacitors is limited because of the extensive changes in the dielectric properties associated with the phase transition at the Curie temperature (T_c), which results in low dielectric characteristics at room temperature (RT). The properties of BTO ceramics, such as RT dielectric properties, dielectric breakdown strength (DBS), and temperature and electrical field stability, can be modulated by adding the dopants. In this work, we studied the changes in the dielectric properties and energy storage performance of BTO ceramics with the addition of Sm₂O₃. BTO ceramics were synthesized via a solid-state route, and varying amounts (0.25, 0.5, 1.0, and 2.5 mol%) of Sm₂O₃ were doped. An increase in Sm₂O₃ content led to a reduction in tetragonality and induced grain growth. As tetragonality is reduced and grain growth realized, the T_c is lowered, thereby increasing the dielectric constant at RT. Furthermore, the stability of the dielectric properties under an applied electric field improves with increasing Sm₂O₃ content. Comparative analysis of the hysteresis characteristics (polarization–electric field; P–E) with varying Sm₂O₃ contents revealed a minimal change in saturation polarization (P_s), while remanent polarization (P_r) decreased from 9.3 to 6.1 µC/cm², exhibiting a slender P–E loop. Additionally, with increasing Sm₂O₃ content, the DBS increased. Sm₂O₃-doped BTO ceramics decreased P_r by approximately 3.2 μC/cm² compared to pure BTO, and the DBS increased from 8 to 10 kV/mm with the addition of Sm₂O₃. Consequently, owing to the increased DBS and decreased P_r, the energy storage density increased from 0.29 to 0.46 J/cm³. Thus, Sm₂O₃-doped BTO ceramics exhibited a higher energy storage density of over 160% compared to pure BTO. Simultaneously, it showed an energy storage efficiency of over 90%. This confirms the potential of Sm₂O₃-doped BTO ceramics as capacitors for high-energy storage density applications.