ROLE OF IRON IN CALCIUM PHOSPHATE GLASSES

Some physical properties okf phosphate glasses con‐taining up to about 26 mol% Fe2O2 were studied. Pronounced changes in properties were observed at compositions containingabout 6, 10, and 13 mol% Fe2O3. The X‐ray diffraction spectra of devitrified (heat‐treated) samples showed new compounds near these compositions. Electron spin resonance and optical studies confirmed the presence of Fe3+ and Fe2+ in both 4‐ and 6‐coordination. An increase in total iron in these samples was associated with a decrease in the ratios Fe2+ 4‐coordinated/Fe3+ 6‐coordinated 6‐coordinated and Fe3+ 4‐coordinated/Fe3+ 6‐coordinated up to about 2.0 mol% Fe2O3, as shown by the intensity of the optical absorption bands at about 2.0 and 1.0 μm and by the intensity of the ESR lines at g⋍4.2 and 2.0, respectively. Samples containing up to 4.3 mol% Fe2O3 showed an increase in Fe3+ concentration and a decrease in Fe2+ concentration after gamma irradiation. The electrical conductivity and activation energy decreased sharply with increasing Fe2O3 content. Copyright © 1969, Wiley Blackwell. All rights reserved