FERROELECTRIC DOMAIN-STRUCTURE AND INTERNAL BIAS FIELD IN DL-ALPHA-ALANINE-DOPED TRIGLYCINE SULFATE

Single crystals of ferroelectric triglycine sulfate (TGS) have been grown from solutions containing 10 and 30 mol% of DL-alpha-alanine. Crystal form, domain structure and distribution of internal bias field E(b) in these DL-alpha-alanine-doped triglycine sulfate: (DLATGS) crystals were investigated. Although the crystal form is influenced by the doping, it shows the symmetry of 2/m similar to pure TGS. The intensity and direction of E(b) distinctly depend on the crystal growth sector. The directions of E(b) in matching sectors in both b sides of the seed crystal are opposite to each other. Hence the domain structure has a mirror symmetry normal to the b-axis. These features of DLATGS are plainly explained by considering the chirality of alanine and the already-known properties of LATGS.