Study of inelastic neutron scattering and by the Raman effect, of the soft mode in the prototype phase of Hg₂Cl₂

Abstract

Preliminary experiments of inelastic neutron scattering confirm the hypothesis that the purely ferroelastic transition in Hg2Cl2 is induced by the condensation of a transversal acoustical model at one * point of the first Brillouin zone in the tetragonal phase. Second-order Raman spectra show that the frequency of the soft mode in the prototype phase is given by the relation nu 2=0.35 (T-184)(cm-1)2.