MOSSBAUER SPECTROSCOPIC STUDIES OF THERMAL-DECOMPOSITION PRODUCTS OF HEXACYANOFERRATE(II) COMPLEXES

The Mossbauer spectra of hexacyanoferrates(II) of alkaline earth metals (Mg, Ca, Sr, Ba) and of La, Ti, Zr, Th, VO2+ and UO22+ exhibit single line (delta = -0.08-0.20 mms-1) at room temperature. Uranyl hexacyanoferrate(II), however, exhibits a large line width (F = 0.53 mms-1) probably due to unresolved quadrupole splitting suggesting some interaction of UO22+ with [Fe(CN)6]4-. In general, delta values show decreasing trend with increasing charge on the outer cations. T hermogravimetric studies upto 600-degrees-C show constant weight in the range 52.0-80% except for Mg hexacyanoferrate(II) which gave 30.3% residue. An attempt has been made to identify the intermediate and end products by Mossbauer spectroscopy. It is suggested that in most cases, a mixture of ferrites, oxides and carbide (Fe3C) along with iron metal may be formed as end products.