The structural properties of liquid and quenched sulphur II

Neutron diffraction experiments over the momentum transfer range 0<Q(AA)^-1<40 have been used to investigate the structural properties of liquid sulphur from 140 degrees C up to 300 degrees C, i.e. from conditions near the melting point of sulphur up to temperatures well above its lambda -transition (T_lambda =159 degrees C), and to study how the structure of sulphur rapidly quenched from different liquid temperatures changes in relation to the corresponding liquid structure. The data have been Fourier transformed to give an accurate pair correlation function g(r) from which absolute numbers and distances of atoms in given molecular configurations may be obtained. The results indicate which molecular bonds are changed in the different solid and liquid states and shed new light on the lambda -transition from a molecular point of view. In particular we show that the number of nearest neighbours probably increases with temperature above the lambda transition. The data on g(r) are also interpreted with recent reverse Monte Carlo calculations.