O'Neill, H. S. C. and James, M. and Dollase, W. A. and Redfern, S. A. T. (2005) Temperature dependence of the cation distribution in CuAl2O4. European Journal of Mineralogy, 17. pp. 581-586. DOI https://doi.org/10.1127/0935-1221/2005/0017-0581
![]() |
PDF
Temp_-_Redfern.pdf Restricted to Registered users only Download (453kB) |
Abstract
The temperature dependence of the cation distribution in CuAl2O4 spinel has been determined from 600 to 1100°C on quenched specimens by powder X-ray diffraction, and from room temperature to 1000°C by in-situ high-temperature powder neutron diffraction. The results, in agreement with earlier work, show that CuAl2O4 is a largely normal spinel, which is already highly disordered at 600°C, the lowest temperature at which the cation distribution is inferred to be in equilibrium, with an inversion parameter, x, at this temperature of 0.35 ± 0.005 from the neutron diffraction experiments. Increasing temperature to 1000°C only causes a modest increase in x, to 0.40 ± 0.005. This somewhat unusual behaviour may be ascribed to local distortions from the Jahn-Teller effect in both octahedrally and tetrahedrally coordinated Cu2+. Thermodynamically, the ordering may be described either with a large entropy of disordering, or alternatively, with a large and positive quadratic term in the enthalpy of disordering. The Jahn-Teller effect produces no long-range distortion of the structure, which has cubic symmetry (space group Fd–3m) under all investigated conditions
Item Type: | Article |
---|---|
Uncontrolled Keywords: | 2005 AREP 2005 P IA49 |
Subjects: | 03 - Mineral Sciences |
Divisions: | 03 - Mineral Sciences |
Journal or Publication Title: | European Journal of Mineralogy |
Volume: | 17 |
Page Range: | pp. 581-586 |
Identification Number: | https://doi.org/10.1127/0935-1221/2005/0017-0581 |
Depositing User: | Sarah Humbert |
Date Deposited: | 25 Aug 2010 10:40 |
Last Modified: | 23 Jul 2013 09:59 |
URI: | http://eprints.esc.cam.ac.uk/id/eprint/1765 |
Actions (login required)
![]() |
View Item |