Superparamagnetic behaviour and hyperfine interactions in ferrous hydroxide II and green rust I

The existence of a ferrous hydroxide, 2Fe(OH)2, FeOHCl, containing Cl− ions substituted for OH− ions has been confirmed. The 4.4 K spectra of this hydroxide variant and green rust I obtained by oxidation are analysed in terms of a mixture of quantum states and the superparamagnetic behaviour at higher temperatures gives some informations on the particle size distribution and the mechanism of oxidation.