Growth and ferroelectric properties of l-, d-, and dl-methionine-doped triglycine sulfate crystals

Single crystals of triglycine sulfate (TGS) doped with l-, d-, and dl-methionine have been prepared. Doping effects on the crystal morphology, the ferroelectric domain structure, and the generation of internal bias field Eb were investigated. These effects were compared with each other and also compared with those of alanine-doped crystals. Though l-methionine-doped crystals show the asymmetric morphology analogous to l-alanine-doped crystals, these two crystals are distinct from each other in their domain structure and the generation of Eb. It was ascertained that the asymmetry caused by l- and d-methionine are mutually reversed in the b-axis. For the doping of racemic mixture dl-methionine, we could recognize the overlap of doping effects caused by the both enantiomers of methionine.