DOMAIN FORMATION IN THE ORDER-DISORDER PHASE-TRANSITION OF RBSCN

The order-disorder phase transition in RbSCN connected with a head-tail reorientation of the linear SCN molecule is investigated by diffuse neutron scattering techniques. The experiment corroborates earlier findings in the isostructural compound KSCN showing that disordering occurs by the increased formation of antiphase domain boundaries whereas within the bulk of the domains the SCN molecules remain locally in an ordered configuration even at temperatures near the melting point. A comparison with KSCN indicates that the strong asymmetry of the critical behaviour with respect to T(c) is caused by the influence of elastic interactions on the domain morphology.