Mössbauer investigation of iron-doped triglycine sulphate

Abstract

A Mössbauer investigation of iron-doped triglycine sulphate (tgs) has been made in order to investigate the changes occurring at the iron nuclei as the properties of tgs change with temperature. Variations in the Mössbauer spectra at temperatures above the normal Curie point for undoped tgs (49 °C) have been correlated with the behaviour of polarisation-voltage hysteresis loops for the iron-doped material. The loops persist above T_c and continue to show asymmetry up to 60 °C. Above this temperature an anomalous increase in Mössbauer quadrupole splitting occurs. On cooling the specimens from 60 °C to below 49 °C the loops reappear but show no bias; bias is gradually restored over a period of hours. Similarly, the quadrupole splitting does not decrease immediately the temperature is lowered, but only after a similar period of time has elapsed. These results are discussed and possible mechanisms for the internal bias field are suggested.