Dysprosium doping induced effects on structural, dielectric, energy storage density, and electro-caloric response of lead-free ferroelectric barium titanate ceramics

This work highlights the influence of dysprosium (Dy) doping on structural, dielectric, ferroelectric, energy storage density (ESD) and the electro-caloric(EC) response of solid state synthesized Ba_1−xDy_xTiO₃ (BDT) ceramics with a composition of x varying from 0 to 0.05. The X-ray diffraction and Raman studies suggest that BDT ceramics exhibited pure perovskite tetragonal phase. Scanning electron microscopy (SEM) analysis evidences that Dy doping causes a significant reduction in grain size. The Ba_0.99Dy_0.01TiO₃ ceramics exhibited enhanced dielectric constant and ferroelectric polarization due to the optimum mobility of domains. The temperature-dependent dielectric studies depict that the tetragonal ferroelectric—cubic paraelectric phase transition temperature (T_c) is shifted from 140 to 80 °C as x varies from 0 to 0.05. Further, BDT ceramics are found to be normal ferroelectric at low composition and is of relaxor type at x = 0.05. The Ba_0.99Dy_0.01TiO₃ ceramics exhibited optimum recoverable ESD of 278 mJ/cm³ and an efficiency (η) of 67% at an electric field of 50 kV/cm. Moreover, the values of ESD and η are stable up to 10⁷ cycles and at different operating temperatures ranging from RT to 70 °C. Besides, the Ba_0.99Dy_0.01TiO₃ ceramics demonstrated an enhanced EC effect with an adiabatic temperature change (ΔT) \(\approx\) $\approx$ 1.92 K in the vicinity of T_c at a field of 50 kV/cm and an EC responsivity (ΔT/E) \(\approx\) $\approx$ 0.38 K m/MV compared to other BT based ceramics.