Application of new thermopiezoelectric effect to thermo- and piezoelectret records

It was originally shown that partially clamped piezoelectric crystals decrease the symmetry of their polarization response to thermal or elastic excitation. As a result any ordinary piezoelectric material (such as /spl alpha/-quartz) and even materials that are pyroelectric perpendicularly to their unique polar axis (such as Y-cut tourmaline) acquire the polar (vectorial) electric response on scalar thermal influence. In connection with this effect we discovered Y-surface thermoinduced electric charges on LiTaO/sub 3/ crystals which manifest themselves through electrooptical patterns. A "thermoelectret" effect is likely to be applied as reversible thermoinduced records. Our recent study uncovered a simple stress-induced method to produce well-defined and reversible records on Y-LiTaO/sub 3/ plates that can be ascribed to a "piezoelectret" nature.