Studies of the crystal structure of triglycine sulfate in connection with its ferroelectric phase transition

Abstract

The crystal structure of triglycine sulfate has been refined at 19°C and 37°C in the ferroelectric phase and at 57°C in the paraelectric phase, by using the data collected by a four-circle automatic diffractometer. Positions of 14 hydrogen atoms out of the 17 have been determined and those of the non-hydrogen atoms refined at 19°C, with the discrepancy factor R of 0.046. Refinement of the structures at 37°C and 57°C was made for non-hydrogen atoms, resulting in the R factor of 0.074 in both cases. The split atom method was used for the determination of the 57°C structure. Obtained results have established that the ferroelectric phase transition of TGS is of the order-disorder type.