ESR spectroscopic study on the incorporation of Fe(III) into Li2O-Al2O3-B2O3 glasses

Abstract

The X band ESR spectra at 77 and 300 K of Li2O—Al2O3—B2O3 glasses investigated comprize four resonances, which can be assigned to Fe3+ ions brought into the samples by the raw materials, mainly by alumina. Signals at g' = 3, 2.3, 2.07 are due to Fe3+ ions incorporated into an autonomous FexOy phase or respective cluster-like precursors. The amplitude of the g' ≈ 4.3 signal typical for the Fe3+ ion in oxidic glasses corresponds with the Li2O content of the glasses. This indicates that the Fe(III)/∑ Fe ratio is mainly influenced by the ability of the Li+ ion to stabilize [FeO4/2]- , i.e., four-fold coordinated Fe(III) can only be stabilized if the Li+ content of the glasses is sufficiently large.