Suppression of switchable polarization in KDP by ionizing radiation

Abstract

Switching curves were obtained from ${\mathrm{KH}}_{2}{\mathrm{PO}}_{4}$ single crystals exposed to x-ray radiation for various time intervals, up to 8 h. The applied electric field was varied between 370 and 740 V/cm, as well. The temperature was held constant at 99 K. The switching curves were fit to a three-parameter nucleation and growth model based on the original works by Johnson and Mehl, and independently by Avrami. The two dynamic parameters, characteristic time ${t}_{c},$ and effective domain wall dimensionality $n,$ produced values consistent with unirradiated studies, however, they did not show any clear dependancy on exposure time. The switchable polarization $P$ decreased with increasing exposure time. A simple exponential decay is used to describe $P$ as a function of exposure time. The rate coefficient $k$ for the exponential, decreases with increasing electric field.