Meducin F , Redfern S A T , Le Godec Y , Stone H J , Tucker M G , Dove M T , Marshall W G , American Mineralogist , 89 (2004) p.981-986, Study of cation order-disorder in MgAl2O4 spinel by in situ neutron, diffraction up to 1600 K and 3.2 GPa, Sample at T = 1507 K and P = 3.2 GPa, inversion parameter x = .633