Novel Actuator Materials. Monomorphs and Photostrictive Actuators

摘要

Photostriction is the superposition of photovoltaic and piezoelectric effects.Perovskite (Pb,La)(Zr,Ti)O3 ceramics doped with WO3 exhibit large photostriction under irradiation of near-ultraviolet light, and are applicable to remote control actuators. Highlights of the 3.5 years activity include: impurity doping study, polarized light effect and photo-induced mechanical resonance. The photostrictive effects in the PLZT were investigated as a function of B-site impurity doping. Donor doping was found to reduce both the grain size and room-temperature dielectric constant, influencing the photovoltaic effect. WO3 and Ta2O5 doping increase the photovoltaic response, but do not significantly affect the piezoelectric effect using linearly polarized light, angular dependence of the photovoltaic voltage and current on the light-polarization orientation with respect to the spontaneous polarization was observed in the PLZT. This angular dependence was consistent with the symmetry of the poled ceramic. Photo-mechanical resonance of a PLZT bimorph has been successfully induced using chopped UV irradiation, having neither electric lead wires nor electric circuit. The remarkable response speed improvement by 5 orders of magnitude during these 3.5 years could verify the feasibility of these PLZT photostrictive materials for practical actuator applications which are relevant to Army needs.