Effect of donor doping in B sites on the electrocaloric effect of BaTi1−xNbxO3 ceramics

Abstract

This paper demonstrates the effect of donor doping in B sites on the electrocaloric effect (ECE) in BaTi_1−xNb_xO₃ (x = 0–0.01) ferroelectric ceramics. The Nb substitution for Ti does not affect the formation of the perovskite structure, while it obviously inhibits the grain growth in sintering process. The donor doping of Nb controls the ferroelectric phase transition more efficiently than equivalent substitutions in either the A or B sites. It lowers the phase transition temperature about one order of magnitude faster than an equivalent substitution, so the ECE ΔT_max shifts accordingly. Nb doping also diffuses the phase transition, so that the ECE ΔT_max reduces and the peak becomes much wider. When compared with BaTiO₃, the ΔT_max of BaTi_0.994Nb_0.006O₃ drops one third, while the full width at half maximum increases two fold, indicating a better refrigeration capacity.