Infrared studies on some ferroelectric compounds of glycine

The infrared absorption spectra of monoglycine nitrate, diglycine nitrate, triglycine sulphate, their deuterated and ¹⁵N (glycine and HNO₃) substituted analogs have been investigated at room temperature and at liquid N₂ temperature. These data have been utilized to suggest the nature of the binding between the polyatomic units in the respective crystal lattices. Based on these studies a plausible switching mechanism in the ferroelectric phase of diglycine nitrate is proposed. The data on triglycine sulphate are consistent with the reported crystal structure and the proposed switching mechanism. There is no indication of any phase transition in monoglycine nitrate between room temperature and liquid N₂ temperature.