Multiferroics and in particular BiFeO3 have recieved alot of interest. The potential of multiferroic materials to be incorporated into many devices such as sensors and memory devices make them highly topical. BiFeO3 is of particular interest since it exhibits both room temperature antiferromagnetic ordering (TN ~ 350 oC) and ferroelectric ordering (Tc ~ 825 oC). More recently the incorporation of Dy has been shown to enhance the magnetic properties of BiFeO3 materials. Increasing Dy content results in a composition driven first order phase transition from rhombohedral to an alternative symmetry proposed as orthorhombic. However the symmetry of this later phase is subject to debate in the literature. It is proposed to conduct powder neutron diffraction experiments with the aim of elucidating the structural effects of Dy incorporation into the BiFeO3 lattice.