Ferroelectricity in SbSI

The photoconducting compound SbSI was found to be ferroelectric with a Curie point at 22°C. It has a high spontaneous polarization of $P_s=25\mathrm{}\mu \mathrm{C}/{\mathrm{cm}}^2$ and a small coercive field strength of $E_c=100\mathrm{}$ V/cm at 0°C. The dielectric constant at the Curie point reaches values as high as 50 000. The switching is relatively fast and depends on the applied field according to a power law. It appears that the unusually large field-induced shift in absorption edge in SbSI and its electromechanical behavior can be explained by the fact that the material becomes ferroelectric below room temperature.