Synthesis and NMR studies of ~(17)O enriched AM_2O_8 phases

摘要

This paper describes synthetic routes to produce highly ~(17)O enriched samples of the negative thermal expansion materials ZrW_2O_8 and ZrMo_2O_8. In the case of ZrW_2O_8 enriched samples can be produced either via enriched Zr~(17)O_2 and W~(17)O_3, which have themselves been characterised by both X-ray diffraction and solid state ~(17)O NMR, or via the hydrated material ZrW_2O_8 centre dot xH_2~(17)O. In the case of ZrMo_2O_8 energy dispersive in-situ diffraction experiments have shown that cubic ZrMo_2O_8 can be directly hydrated to form an enriched sample of ZrMo_2O_7(OH)_2 centre dot 2H_2O which can subsequently be transformed back to enriched cubic ZrMo_2O_8. ~(17)O NMR data of enriched ZrW_2O_8 materials are reported.