ELECTRON-SPIN-RESONANCE OF FE3-TEO2-FE( CENTERS IN ALPHA)

Two prominent Fe3+ centres were observed by ESR in alpha-TeO2:Fe singl e crystals. One of them exhibits C-2 symmetry (Fe3+(C-2) centre) and t he other one exhibits C-1 symmetry and also superhyperfine interaction s with two hydrogens (Fe3+-2H-V-o(C-1) centre). The Fe3+(C-2) centre i s believed to be an interstitial Fe3+ ion; the nature of its superhype rfine interaction with neighbouring Te nuclei contributes to this assi gnment. The Fe3+-2H-V-o(C-1) centre is attributed to a substitutional Fe3+ ion with two neighbouring hydrogens and a local oxygen vacancy.