Diagnostics of the volume distribution of conductivity in solids by electroacoustic methods

The principles underlying the use of the acoustic probe and electrostriction methods for the nondestructive measurement of the volume distribution of the electric field intensity and charge density in solids are discussed. Acoustic probing consists of recording an electric signal generated by a charge or polarized sample under the action of a mechanical pulse causing a compression wave. The electrostriction method is based on recording an acoustic signal in the surface of an electrified sample which is affected by an electric pulse. Analysis shows that the two methods are equivalent as regards their physical basis and information provided. The fields of application of these two methods are shown to be somewhat different. Acoustic probing is more correct and technically simple when high-ohmic materials with a long charge relaxation time are under investigation. As an example, the study of diffusion in the nitric-acid-polyethylene system is considered