Derivatives of the perovskite NaNbO3 are currently being studied as benign replacements for piezoelectric Pb(Zr,Ti)O3. In order to understand the structure-composition-property relationships in such materials (for example K, Li or Ag-doped NaNbO3) it is necessary to understand the short range as well as the 'crystallographic' (long-range) structure. In this experiment we will collect data suitable for PDF analysis (via RMC modelling) on specifically selected, doped variants of NaNbO3. The data obtained will complement our ongoing studied by conventioanl crystallography, solid state NMR and electrical measurements in order to build a comprehensive picture of the complex structural behaviour of these materials and its relationship to their physical properties.