Structure of the hydrated pyrochlore NaW2O6· nH2O.

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The Bragg Institute, Australian Nuclear Science and Technology Organisation
The pyrochlore NaW206.2H20 is of interest due to its ion exchange capabilities and application to the separation of radioactive Cs and Sr from Intermediate Level Liquid Waste. The material was hydrothermally synthesised and subsequently examined using variable temperature powder neutron diffraction to determine the structure and positions of H20 in the lattice. Neutron diffraction was essential to determine the location of the water within the pyrochlore lattice. A previous neutron diffraction study by Slade[1] of pyrochlore-type antimonic acid exchanged with D20 found interstitial oxygen atoms present as a mixture of H20 and H30+ in the M2062‘ framework. Analysis of the powder neutron diffraction patterns of NaW2O5.2H2O collected using the Medium Resolution Powder Diffractometer (l\/IRPD) at ANSTO's HIFAR facility was performed with the software package RlETlCA[2]. The refinements show an ordered 1 H20 molecule to be present with the 0(2) on a 32e site and the H(1) 48f site. Details of the structure will be presented and the structure of this material will be I compared with that of other hydrated pyrochlores. © The Authors
Physical copy held by ANSTO Library at DDC 539.7217/2
ANSTO, Neutron guides, Radioisotopes, Pyrochlore, Liquid wastes, Ion exchange, Neutron diffraction
Thorogood, G. J., Kennedy, B. J., & Luca, V. (2006). Structure of the hydrated pyrochlore NaW2O6· nH2O. Paper presented at the Eighth International Conference on Neutron Scattering ICNS 2005: "Neutrons for structure and dynamics - a new era", Sydney Convention & Exhibition Centre, Sydney, Australia, 27 November-2 December 2005. In Final Programme and Abstract Book, (pp. 192).