Total scattering and reverse Monte Carlo study of the 105 K displacive phase transition in strontium titanate

We report a study of the displacive phase transition in SrTiO using neutron total scattering with analysis by the reverse Monte Carlo method. The resultant configurations have been analysed in terms of bond distance and bond angle distribution functions, and using recently developed methods based on geometric algebra (GA). The resultant picture is that the short-range order in SrTiO closely follows the long-range order, with very little disorder in the high-temperature phase. This result is in contrast to similar work carried out on the displacive phase transition in quartz (Tucker et al 2000 J. Phys.: Condens. Matter. 12 L723-30). The differences between these two systems arises from the fact that there are many more Rigid Unit Modes in quartz, a point that is quantified by the GA analysis.