Synthesis and NMR studies of 17O enriched AM2O 8 phases

Abstract

This paper describes synthetic routes to produce highly 17O 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 17O 2 and W 17O 3, which have themselves been characterised by both X-ray diffraction and solid state 17O NMR, or via the hydrated material ZrW 2O 8⋅ xH 2 17O. 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⋅2H 2O which can subsequently be transformed back to enriched cubic ZrMo 2O 8. 17O NMR data of enriched ZrW 2O 8 materials are reported.