Ferroelectricity in Tetramethylammonium-Trichloro-Mercurate

Tetramethylammonium-trichloro-mercurate, [N${\left(\mathrm{C}{\mathrm{H}}_3\right)}_4$]·Hg${\mathrm{Cl}}_3$, is ferroelectric between -80° and +200°. Above 200° it decomposes without showing a Curie point. At room temperature the spontaneous polarization is about 1.2 μcoul/${\mathrm{cm}}^2$, the coercive field 3 kv/cm and the dielectric constant 60.