High energy storage performance of Ca0.15(Sr0.6Ba0.4)0.85Nb2-Ta O6 relaxor ferroelectric ceramics

A series of lead-free Ca 0.15 (Sr 0.6 Ba 0.4 ) 0.85 Nb 2- x Ta x O 6 (CSBNT x ) unfilled tetragonal tungsten bronze (TTB) ferroelectric ceramics were fabricated via a traditional solid-state reaction process by substituting Ta 5+ for Nb 5+ in B sites to enhance relaxor behavior. The introduction of Ta 5+ , which has a strong refractory character, resulted in pronounced grain size reduction and improvement of the breakdown strength. The distortion of the BO 6 octahedral lattice promoted the movement of the relaxor transition peak toward lower temperatures. The weakening of the covalency of the B–O bond destroyed the ferroelectric domain structure, resulting in a more slender P - E hysteresis loop, ultimately improving the efficiency at higher ratios of Ta. Finally, a relatively good recoverable energy-storage density of 1.42 J/cm 3 and a high energy storage efficiency of 81.9% were obtained for Ca 0.15 (Sr 0.6 Ba 0.4 ) 0.85 Nb 1.4 Ta 0.6 O 6 . Optimal charging-discharging performance, with a discharge time of τ 0.9 = 69 ns, a current density ( C D ) of 1110.9 A/cm 2 , and a power density ( P D ) of 94.43 MW/cm 3 , was achieved in CSBNT 0.6 ceramics.