Synthesis and NMR studies of 17O enriched AM2O8 phases

This paper describes synthetic routes to produce highly 17O enriched samples of the negative thermal expansion materials ZrW2O8 and ZrMo2O8. In the case of ZrW2O8 enriched samples can be produced either via enriched Zr17O2 and W17O3, which have themselves been characterised by both X-ray diffraction and solid state 17O NMR, or via the hydrated material ZrW2O8⋅xH217O. In the case of ZrMo2O8 energy dispersive in-situ diffraction experiments have shown that cubic ZrMo2O8 can be directly hydrated to form an enriched sample of ZrMo2O7(OH)2⋅2H2O which can subsequently be transformed back to enriched cubic ZrMo2O8. 17O NMR data of enriched ZrW2O8 materials are reported.