Waves In Pyroelectrics

摘要

The propagation of waves in an infinite pyroelectric medium is studied in this paper. The governing equations for the pyroelectrics are written in three versions which are (1) the version containing heat flow, (2) the stiffened version and (3) the compact version. The results obtained by using versions (1), (2) and (3) are the same. Four characteristic wave velocities are found, three being analogous to those of elastic waves and the fourth wave, which is predominantly a temperature disturbance, corresponding to the heat pulse known as the second sound. It is found that all the velocities and attenuation coefficients are related to the wave normal and the material constants. The effect of the electric properties on the wave propagation is considered, which indicates that the temperature wave is not sensitive to pyroelectricity and piezoelectricity in the discussed case. The effects of relaxation time x are estimated by several different values, and the results indicate that x has very little effect on the mechanical velocities; whereas it plays a large role on the velocity and attenuation of temperature wave. The effects of the terms containing x on the attenuation are researched in detail in one-dimensional case for clarity.