Raman spectroscopic study of tris-sarcosine calcium chloride in the antiferroelectric phase

The polarized Raman spectra of (CH₃NHCH₂COOH)₃CaCl₂ (TSCC) have been obtained applying hydrostatic pressure in the paraelectric, ferroelectric and in the pressure-induced antiferroelectric phase. The phase transition between the paraelectric or the ferroelectric and the antiferroelectric phase appears to be of first order. No cell doubling could be observed in the antiferroelectric phase. The space group $\text{P2}{}_1\text{a (C}{}^5{}_{\mathrm{2h}}\text{)}$ for TSCC in this phase is compatible with our experimental results. The pressure-dependence of the Raman-active soft mode is discussed qualitatively.