The effect of copper(II) on the Formation of Magnetite from Colloidal Iron (II) Hydroxide

The rate of self‐decomposition of iron(II) hydroxide doped with various amounts (0–6 atomic%) of Cu(II) was determined in the absence of oxygen at the temperature range of 30 to 50°C. The maximum rate and the minimum activation energy were observed at 1% Cu/Fe. The result was attributed to the two simultaneous actions of Cu2+, i.e., the distortion effect on coordination complex of Fe2+ by Cu2+ to ease the structural transformation to magnetite and the hindering effect on magnetite formation revealed consequently in the growth of Fe(OH)2 crystals. Both effects were proved by X‐ray diffraction and election‐microscopic observations.