Particle and crystallite sizes extracted from the SEM and XRD measurements, respectively, of the α-Fe nanoparticles obtained by reduction at different temperatures and hydrogen pressures.

Temperature (°C)	Particle size (nm)	Crystallite size (nm)	Hydrogen pressure (bar)
390	215 ± 37	263 ± 46	100
310	96 ± 47	133 ± 12	100
270	67 ± 2	79 ± 1	100
210	47 ± 5	41 ± 1	530