Crystal‐field properties of Fe in brucite Mg(OH)₂

Abstract

Abstract Samples of brucite Mg(OH) 2 containing iron are investigated using 57 Fe Mößbauer spectroscopy. The values of the isomer shift and the quadrupole splitting, measured at room temperature, are IS = 1.15 mm/s relative to metallic iron and QS = 2.94 mm/s. From these values, iron is deduced to be in a high spin divalent state. From the magnitude of the QS it is inferred that the ground state associated with the crystal‐field splitting of the 3d levels for Fe 2+ in the trigonally distorted oxygen octahedron is a singlet, in agreement with the results of calculations of this splitting. It is argued that this may lead to an increase of the trigonal distortion and provide an explanation of the anomaly in the c/a lattice parameter ratio observed in Fe(OH) 2 in comparison with other compounds forming the brucite structure.