BiFeO3 continues to be the most widely studing multiferroic material as a result of its room temperature magnetic and electric ordering. However, many barriers limit the commercial viability of BiFeO3 including high leakage currents and weak magnetoelectric coupling. More recently researchers have looked to doping BiFeO3 with rare earths such as La3+ or Nd3+. Whilst A-site cation size effects and rare earth polarizability have been shown to be important it has not been possible to generate a global understanding of these materials which would allow for predictable design. We have synthesised materials which have allowed us to decouple these two effects allowing us to probe the structure-property effects of A-site doping in BiFeO3. We propose to extend this lab based study to investgate cation displacement and octahedral rotation by neutron diffraction giving an enhanced understanding.