An investigation of crystalline ferric thiocyanate

Abstract

In 1961, while at the Chalk River Research Establishment, Canada, working on Mössbauer powder absorption spectra of many iron compounds, Duncan J. F. Duncan, unpublished work. (1961) observed an unexpected result for ferric thiocyanate. Spectra of a sample supplied by the City Chemical Co. of New York were taken regularly over a period of seven months. The spectra were used to determine the two Mössbauer parameters, the quadrupole splitting, (ΔEq), and the isomer shift, (δ). The initial values for both parameters were unexpectedly high but dropped markedly, within approximately six weeks, to quite constant lower values. Neither the values found, nor the change with time, could be readily explained on the basis of previous understanding of either the material or the experimental method. A sample of ferric thiocyanate was prepared by Christie at V.U.W. and Mössbauer spectra of this material, while still fresh, were taken at Bell Telephone Laboratories U.S.A. in 1964. This sample was re-examined approximately 13 months later by Christie, on the V.U.W. Mössbauer spectrometer in Wellington, together with other aged and fresh samples. High initial values of both the quadrupole splitting, and the isomer shift, similar to those of Duncan's earlier study, were found. Also a marked drop in the parameters' values was found on examination of the same sample after the intervening period.