Photovoltaic effect of Sn2P2S6 ferroelectric crystal and ceramics

Abstract

To investigate the photovoltaic effect in Sn2P2S6 ferroelectrics, Sn2P2S6 crystal and ceramic sample that had a high relative density of 95% and a grain size of below I [Lm were fabricated. The steady-state photovoltaic currents under infrared light illumination on both Sn2P2S6 crystal and ceramic sample were observed for the first time. The photovoltaic currents i(pw) on Sn2P2S6 ceramic sample and crystal were 5 and 25 nA/cm, respectively. The difference in the magnitude of the photovoltaic current resulted from the difference in the remanent polarization P-r between the crystal and the ceramic sample. The values of the photovoltaic field E-pv determined from I-V curve for Sn2P2S6 ceramic sample and crystal were 0.2 and 6 V/cm, respectively; these values were several orders lower than that observed on the perovskite-type ferroelectric ceramics. The photovoltaic fields observed in this study were discussed with the conductivity of the crystal and the ceramic sample, in consideration of the figure of merit for the photostriction.