Enhanced aging behaviors and electric thermal stabilities in 0.75BiFeO3-0.25BaTiO3 piezoceramics by Mn modifications

Lead-free 0.75BiFeO(3)-0.25BaTiO(3) (0.75BF-0.25BT) ceramics have been extensively studied because of their high Curie temperature. The aging behavior and thermal stability of piezoceramics play decisive roles in their device applications. In this work, effects of Mn doping on the phase structure, aging behavior, and thermal stability of 0.75BF-0.25BT ceramics were characterized and related mechanisms were investigated. With the increase in Mn content, the typical rhombohedral phase of 0.75BF-0.25BT ceramics changed to the coexistence of pseudo-cubic and rhombohedral phases. Mn modification enhanced the aging behavior and thermal stability of ceramics obviously. The aging rates of d(33) and k(p) for 0.75BF-0.25BT ceramics with 1.0 mol% Mn are 1.3% and 1.1%, respectively, which are only 1/4 those values for the undoped ceramics. The variation of epsilon(r) of 0.75BF-0.25BT ceramics with 1.0 mol% Mn is half of undoped ceramics under 500 degrees C. The depoling temperature of 0.75BF-0.25BT ceramics with 1.0 mol% Mn was 450 degrees C, which is about 200 degrees C higher than that of undoped ceramics. The enhanced aging behavior results from the decreased defect concentrations, and the better thermal stability is owing to the significantly improved poling state due to the enhanced resistivity, large grain size, and decreased crystal distortion by Mn modification. These results reflect that a proper amount of Mn doping is an effective way to enhance the aging behavior and electric thermal stability.

Automated summary

Mn doping has a significant impact on the phase structure, aging behavior, and thermal stability of 0.75BF-0.25BT ceramics, leading to reduced aging rates and enhanced thermal stability. This is due to the decreased defect concentrations and improved poling state resulting from Mn modification.