13C NMR investigations of the ferroelectric phase transition of tris-sarcosine calcium chloride

¹³C NMR spectra were measured for tris-sarcosine calcium chloride (TSCC) crystals in the paraelectric phase (at temperatures of ? 300 and 150 K) and in the ferroelectric phase (at temperatures of 119 K) by double-resonance techniques with proton decoupling. The ferroelastic single crystals were rotated around their three crystallographic axes to derive the tensors of magnetic shielding for the different carboxylic carbon atoms. There is no change of the eigenvalues and eigenvectors of the tensors at the phase transition. The results are consistent with the interpretation of former EPR data.