Auto-reduction in inert helium (99.999% UHP), flowed through an oxygen/moisture trap (Matheson, MTRP-0019-XX) at a flow rate of 50 cm 3 min -1 , was studied at 723 K (0.167 K s -1 ) until the XANES spectra stopped changing (sample dependent, up to 2 h). For the oxidation treatment, the sample was held in oxygen (21 kPa in balance He) at a total flow of 50 cm 3 min -1 while increasing the temperature from ambient to 723 K (0.167 K s -1 ) and holding at temperature for up to 2 h.