Abstract
Three commonly used ferroelectric actuator and sensor materials, namely polyvinylidene fluoride copolymers, lead zirconate titanate piezoceramics (PZT), and lead magnesium niobate-lead titanate relaxors (PMN-PT) at low PT content, are characterized with respect to temperature and driving field amplitude. It is shown that changes in the response and loss with the driving field amplitude are mainly caused by irreversible process and hysteresis effect in the materials, which are different from a nonlinear process. To analyze the driving field amplitude dependence of the response of a piezoelectric material, a representation is proposed which divides the material response behavior into three regions with increased driving field amplitude: 1) a linear response region, 2) a region with increased response sensitivity, nonlinearity and hysteresis, and 3) a saturation and depoling region. Based on this, the operating field limit is clearly defined for different materials and different applications. For ferroelectric relaxor materials, since the magnitude of the field induced piezoelectric coefficients depends on both the dielectric constant and the polarization level, a material with a smaller difference between the temperatures of depolarization and dielectric constant maximum will yield higher piezoelectric constants. In addition, the relaxor materials exhibit large nonlinear effects which may be useful in smart materials and structures.
Get full access to this article
View all access options for this article.