Nd3+ and Nb5+ Co-Substitution Inducing a Large Electrocaloric Response in Na0.5Bi0.5TiO3 Lead-Free Ceramics

Nd3+ and Nb5+ co-substituted (Na0.5Bi0.49Nd0.01)Ti1-xNbxO3 lead-free ceramics are synthesized by conventional solid-state reaction method. The X-ray diffraction study revealed that NBNT-Nb-0 (x = 0.00) ceramics exhibit single phase monoclinic crystal with Cc phase while NBNT-Nb-1 (x = 0.00) ceramics exhibited a dual phase with coexistence of monoclinic and tetragonal systems. The temperature-dependence dielectric study revealed the existence of ferroelectric and antiferroelectric transformations in two independent regions. Further temperature-dependent strain vs. electric field measurements strengthen the ferroelectric to antiferroelectric transformation in the present ceramics. The induced electrocaloric effect (ECE) response showed that a significant change in temperature (ΔT) is obtained at 50 kV cm−1 fields: about 0.69 K for NBNT-Nb-0 and 0.81 K for NBNT-Nb-1 ceramics, respectively. The maximum isothermal entropy change (ΔS) is found to be 0.95 and 1.02 Jkg−1 K−1 for NBNT-Nb-0 and NBNT-Nb-1 ceramics obtained at 50 kV cm−1, respectively. The simultaneous presence of ECE response and isothermal change in entropy (ΔS) is an open window for great potential applications in the field of electronic devices.