Mossbauer spectroscopic studies of thermal decomposition products of hexacyanoferrate(II) complexes

Abstract

The Mossbauer spectra of hexacyanoferrates(II) of alkaline earth metals (Mg, Ca, Sr, Ba) and of La, Ti, Zr, Th, VO²⁺ and UO<img src='http://www.niscair.res.in/jinfo/equation40.gif' border=0> exhibit single line (δ = -0.08-0.20 mms^-1) at room temperature. Uranyl hexacyanoferrate(II), however, exhibits a large line width (Γ= 0.53 mms^-1) probably due to unresolved quadrupole splitting suggesting some interaction of UO<img src='http://www.niscair.res.in/jinfo/twoplustwo.gif' border=0> with [Fe(CN)₆]^4-. In general, δ values show decreasing trend with increasing charge on the outer cations. Thermogravimetric studies upto 600ᵒC 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 offerrites, oxides and carbide (Fe₃C) along with iron metal may be formed as end products.