DC Bias Field Dependence on High-Power Characteristics of PbTiO_3-Pb(Mg_(1/3)Nb_(2/3))O_3 Electrostrictive Ceramics

摘要

The mechanical quality factor Q_m of a normal ferroelectric ceramic vibrator decreases and heat is given off when the vibrator is continuously driven at a high level of vibration stress under a resonant mode. The irreversible motions of ferroelectric non-180° domain walls in the ferroelectric ceramic vibrator cause this unfavorable behavior. The effect of ferroelectric domain structure under the vibration stress on electromechanical characteristics was studied using relaxor ferroelectric electrostrictive (1 - x)PbTiO_(3-x)Pb(Mg_(1/3)Nb_(2/3))O_3 (x = 1.00, 0.95, 0.90) ceramics. The Q_m of the paraelectric Pb(Mg_(1/3)Nb_(2/3))O_3 ceramics was consistently higher than 5000 at a high stress level under a dc bias field. This Q_m is much larger than that of typical hard lead zirconate titanate (PZT) ceramics. The Pb(Mg_(1/3)Nb_(2/3))O_3 ceramics show a considerably large piezoelectric d_31 constant which is comparable to that of hard PZT ceramics. The electrostrictive ceramics are therefore superior electromechanical vibrator materials for high-power devices.