Refinement of Ammonium Perrhenate Structure Using a Pseudo-Spin Model for the Ammonium Ion Orientation
Abstract
A new Rietveld refinement of previously reported powder neutron diffraction data on ND4ReO4 taken over a wide range of temperatures [Powell, Brown, Harnden & Reid (1993). Acta Cryst. B49, 463-468] is reported. Rigid-body constraints are applied to the cation geometry and occupation of a second cation orientation at higher temperatures is permitted. The resulting structure at higher temperatures is to be preferred to the previous structure with a single cation orientation and supports the pseudo-spin theory of cooperative disordering without a phase transition.
- Publication:
-
Acta Crystallographica Section B
- Pub Date:
- February 1997
- DOI:
- 10.1107/S0108768196011160
- Bibcode:
- 1997AcCrB..53...76S