Model MDFs related to sulfobelitic systems: Studies by Fe-57 Mossbauer and electrical impedance techniques

New studies of the MDF-processibility of particular components of potential sulfobelitic clinkers in combination with hydroxypropylmethyl cellulose (hpmc) and/or polyphosphates (poly-P) are presented. The involvement of Al/Fe, P and C atoms in chemical cross-links within amorphous AFm -like reaction products in several subsystems of a complex sulfobelitic clinker/polymer system is examined by (i) Fe-57 Mossbauer spectroscopy (to investigate Fe-atom local environments) and (ii) electrochemical impedance measurements (to characterize conductivity variations). Fe-III atoms are octahedrally coordinated by oxygens in their first coordination sphere, with some replacement of H atoms by C or P atoms in the second coordination sphere, forming cross-links of the type Al/Fe - O - C/P in hydrated products. Impedance spectra were typical of electronically- insulating materials functioning as solid electrolytes, with conductivity values depending on polymer/gel composition as well as on temperature. Copyright (C) 1997 Elsevier Science Ltd.