No abstract

No abstract

No abstract

EPR and magnetic susceptibility measurements on x MnO ·(100-x)[70 TeO 2·25 B 2 O 3·5 SrF 2] glasses, within 0.1 ≤ x ≤ 50 mol% were performed. The number of isolated Mn 2+ ions, participating at the g ≈ 4.3 resonance increases up to 1 mol% MnO and after that decreases to nil for 10 mol% MnO . The number of Mn 2+ ions participating at the g ≈ 2.0 resonance increases when the MnO content rises. From line-width composition dependence of these glasses, for x > 3 mol%, the manganese ions participate in the superexchange magnetic interaction. Magnetic measurements revealed both Mn 2+ and Mn 3+ valence states as simultaneously present in the vitreous matrix and these ions are involved in negative superexchange interactions, being antiferromagnetically coupled.

The Cr 2 O 3 content influence on the structure of 70 TeO 2·25 B 2 O 3·5 SrO glasses, was investigated by infrared and Raman spectroscopies. The results show that BO 3 and BO 4 are among the main structural units in the investigated glasses, together with TeO 3 and TeO 4 units. The presence of chromium ions located in the glass network is well evidenced in the IR and Raman spectra.