Observation of lattice melting at the ferroelastic phase transition inNa2CO3

Abstract
A neutron powder diffraction study of the m=2 ferroelastic phase transition at 755 K in Na2 CO3 is presented, showing the first occurrence of ideal lattice melting. A detailed analysis of the profile of the diffraction peaks shows a striking broadening which develops close to Tc, consistent with recent theoretical predictions for this type of transition.