A multifrequency EPR study of Fe2+ and Mn2+ ions in a ZnSiF6·6H2O single crystal at liquid-helium temperatures

A liquid-helium temperature study of Fe2+ and Mn2+ ions has been carried out on a single crystal of Fe2+-doped ZnSiF6·6H2O at 5-35 K at 170, 222.4 and 333.2 GHz. The spectra are found to be an overlap of two magnetically inequivalent Fe2+ ions, as well as that of an Mn2+ ion. From the simulation of the EPR line positions for the Fe2+ (d6, S = 2) ion the spin-Hamiltonian parameters were estimated for the two inequivalent Fe2+ ions at the various temperatures. From the relative intensities of lines the absolute sign of the fine-structure parameters have been estimated. In addition, the fine-structure and hyperfine-structure spin-Hamiltonian parameters for the Mn2+ ion, present as impurity at interstitial sites, were estimated from the hyperfine allowed and forbidden line positions. The particular virtues of such a single-crystal study vs. that on powders are noted.