The order-disorder phase transition in RbSCN connected with a head-tai
l reorientation of the linear SCN molecule is investigated by diffuse
neutron scattering techniques. The experiment corroborates earlier fin
dings in the isostructural compound KSCN showing that disordering occu
rs by the increased formation of antiphase domain boundaries whereas w
ithin the bulk of the domains the SCN molecules remain locally in an o
rdered configuration even at temperatures near the melting point. A co
mparison 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.