Structural transformations in natural gels according to resonance methods data

摘要

The natural gels of alumo-ferri-sulphate-phosphate composition were studied by means of the Moessbauer spectroscopy, EPR and NMR'H. The investigation of the temperature dependences of the obtained spectra allowed one to establish two intervals in which the structural transformations of gels take place: 213...233 K and 383...423 K. The structural changes depend on the iron content. With the increase of iron content, its role increases, too. In gels containing iron more than 30%, the ferrigels are formed, which transform to hematite after annealing of samples at 1270 K. 10 refs., 7 figs., 2 tabs. (Atomindex citation 27:003976)