We have prepared some new highly crystalline mixed-metals oxides using mild hydrothermal reaction conditions. Some of these are doped niobates, related to the important lead-free electroceramics, and others are new, metastable phases. In order to resolve the structures of these materials we require powder neutron diffraction measurements. We will also study how the materials collapse into more stable solids at elevated temperatures. This will enable us to relate the structures of the solids to the reaction conditions used in their synthesis, with the aim of developing some fine control in the synthesis of complex materials. This work is part of an EPRSC-funded programme (2008-2011) and will form part of a Warwick DTA PhD student now in here final year.