Experimental and Theoretical Investigations of Electromagnetic Radiation Emission from Soft and Hard PZT Ceramics

Abstract

Electromagnetic radiation (EMR) signals from soft (SP 5A) and hard (SP 4) PZT ceramics under the influence of alternating electric fields have been investigated. The 180° oscillations of dipoles present in the piezoelectric ceramics give rise to EMR voltage signals. The soft PZT shows higher EMR signals as compared to the hard PZT which is due to the ease in the movement of dipoles in the soft PZT because of the existing vacancies which is its characteristic feature. On the other hand, the hard PZT having no vacancies does not allow that much free movement of dipoles under the effect of the external stimulus. The EMR signals have been measured using the non-contact detection technique in which an annular antenna made up of copper was placed around the samples to obtain the EMR signals which were measured during the application of an alternating electric field on the samples. The effect of frequency has been experimentally explored and it has been observed that the EMR signal increases with the increase in the frequency of the applied alternating electric field due to the increase in the frequency of oscillations of the dipoles. When the EMR voltage is measured with increasing distance from the sample, it shows the decaying pattern which matches the pattern with which electromagnetic radiations fall off with distance. The results from the analytical model are in agreement with the experimental results. These materials and measurement technique show their potential for wireless sensing applications using piezoelectric materials which have the potential to replace the currently used wired sensors.