EPR investigation of manganese ions in B2O3?11a0 glass matrix

• Published in: Journal of Optoelectronics and Advanced Materials 2007-03, Vol.9 (3), p.629-632
• Main Authors: Toderas, M, Ardelean, I
• Format: Article
• Language: English
• ISSN: 1454-4164

Glasses of the xMn0?(100-x)[3B2O3?BaO] system, with 0.55)(5.50 mol% were prepared and investigated by EPR measurements. Information concerning the structural details of the vitreous matrix revealed by Mn2+ paramagnetic ions distribution on different structural units building the network and coordination were obtained. EPR absorption spectra due to Mn2+ ions were detected for all the investigated samples. The distribution of the Mn2+ ions on several structural units of vitreous matrix revealed by EPR spectra structure depends on the MnO content. In the low concentration range isolated Mn2+ ions were identified in sites of slightly tetragonally distorted octahedral symmetry. They give rise the absorption centered at gar showing a resolved hyperfine structure up to 5 mol% MnO. There are also isolated Mn2+ ions in sites of heavily distorted octahedral symmetry but with strong crystalline fields giving rise to absorption at geff Their intensity is small enough comparatively with those centered at ger k. 2.0 indicated a relatively low concentration of Mn 2+ ions involved in such structural units. In the high concentration range, 10 5. x 5. 50 mol% the progressive clustering of Mn 2+ ions was evidenced by the evolution of the corresponding absorption line at geff Its line-width depends on concentration showing a dipolar broadening within 0.5 x 5 10 mol% and superexchange narrowing for x 10 mol%.