Structural phase transition in ferroelectric glycine silver nitrate

The structural investigation of the ferroelectric phase transition in glycine silver nitrate has revealed that the transition at Tc=218K is due to the displacement of the Ag+ ions from the plane made by the carboxyl oxygens of glycine zwitterions coordinated to it. Since the transition takes place between two ordered structures the thermal anomaly at TcTc is very weak, the transition enthalpy and transition entropy were found to be ΔH=6.6J/mol and the transition entropy ΔS=0.03JK−1mol−1 respectively. These crystals are held together by a network of hydrogen bonds. In order to study these interactions the Raman spectrum of GSN was recorded and discussed in the light of ferroelectricity in glycine complexes in general.