RAMAN-SCATTERING STUDY OF [N(CD3)4]2ZNCL4 UNDER HYDROSTATIC-PRESSURE

Raman spectra were measured for [N(CD3)4]2ZnCl4 over the pressure range 1-2000 bar. The influence of pressure was studied for the ZnCl4 bending modes and the 24 cm-1 phonon peak. The pressure dependence of these modes was interpreted having regard to the phase transitions predicted by the temperature-pressure diagram. The pressure dependence of all the recorded spectra highlights a critical behaviour at about 500 bar which does not correspond to any phase transition in the diagram. This phenomenon was interpreted by consideration of the modulation characteristics.