Atomic ordering in Bi4Ge3O12 melt by reverse Monte Carlo simulations

A three-dimensional structure model which well reproduces experimental structure functions for molten Bi4Ge3O12 and agrees with the results of EXAFS experiments has been constructed by reverse Monte Carlo simulations. From the model atomic configuration the partial atomic distribution functions, the partial coordination numbers and distances of molten Bi4Ge3O12 have been extracted. It has been found that, on an atomic scale, molten Bi4Ge3O12 may well be described as an assembly of disconnected GeO4 tetrahedra dispersed in a medium of weakly correlated Bi and O atoms. The structural differences between molten and crystalline Bi4Ge3O12 have also been discussed in an attempt to clarify the reasons that make the process of pure Bi4Ge3O12 crystals growth from the melt difficult.