Table 1. High resolution X-ray diffraction measurements, derived oxidation parameter and average oxidized layer thickness.

Growth Time (min)	Avg. Particle Size by XRD (nm) ± std error	Lattice parameter a by XRD (nm)	Oxidation parameter z FeIII(FeII (1-z)FeIII (1+2z/3)[ ]z/3	Avg. Oxidation layer thickness (nm)
1	7.6 ± 0.2	0.83664 ± 0.00055	0.79	1.5
5	14.5 ± 0.3	0.83772 ± 0.00079	0.6	1.9
10	16.0 ± 0.3	0.83832 ± 0.00018	0.46	1.5
30	16.0 ± 0.3	0.83869 ± 0.00021	0.35	1.1
100	19.4 ± 0.4	0.83895 ± 0.00024	0.26	0.9