Ferroelectricity in Glycine Silver Nitrate

Glycine silver nitrate, N${\mathrm{H}}_2$C${\mathrm{H}}_2$COOH·AgN${\mathrm{O}}_3$, is ferroelectric below -55°C. At -195°C the spontaneous polarization is 0.55×${10}^{-6\mathrm{}}$ coulomb/${\mathrm{cm}}^2$, and the coercive field is 740 v/cm. The transition appears to be of second order. A differential thermal analysis does not reveal a specific heat anomaly. No dielectric anomalies appear between 4°K and -55°C. The spontaneous polarization here, as in triglycine sulfate and isomorphs, is attributed to disturbance of the planarity of the glycine ion by the crystalline field.