Shear Piezoelectric and Dielectric Properties of $${\hbox {LiNbO}}_{3}$$ LiNbO 3 , PMN-PT and PZT-5A at Low Temperatures

Abstract

We have measured the low-temperature shear piezoelectric and dielectric constants of single-crystal lithium niobate ( $$\hbox {LiNbO}_{3}$$ ) and lead magnesium niobate–lead titanate (PMN-PT), and of ceramic lead zirconium titanate (PZT-5A) transducers between room temperature and 78 mK. The piezoelectric and dielectric coefficients $$d_{15}$$ and $$K^{\sigma }_{15}$$ all decrease with temperature, although the total change in $$d_{15}$$ is only about 7% for $$\hbox {LiNbO}_3$$ . The values of $$d_{15}$$ for PZT-5A and PMN-PT are much larger at room temperature but decrease much more rapidly, by factors of 4 for PZT-5A and 10 for PMN-PT. For $$\hbox {LiNbO}_3$$ , $$d_{15}$$ is constant below 50 K, but in both PZT-5A and PMN-PT $$d_{15}$$ continues to decrease nearly linearly to the lowest temperatures. The behavior of the dielectric constant of each material mirrors that of $$d_{15}$$ , reflecting their common ferroelectric origins. The piezoelectric voltage constants $$g_{15}$$ are similar in the three materials and are only weakly temperature dependent. For actuator applications where large displacements are needed, PMN-PT and PZT-5A have much larger $$d_{15}$$ values than $$\hbox {LiNbO}_3$$ , but this advantage essentially disappears at low temperatures and $$\hbox {LiNbO}_3$$ is a better choice in many applications. For sensor applications where $$g_{15}$$ determines a transducer’s output voltage, the three materials have similar sensitivity for high-frequency applications like ultrasonics. At low frequencies, however, they are less sensitive as voltage sensors and the use of charge or current amplifiers is preferable.