Biswas, Kaushik and Sontakke, Atul D and Sen, Ranjan and Annapurna, K (2012) Luminescence properties of dual valence Eu doped nano-crystalline BaF2 embedded glass-ceramics and observation of Eu2+ -> Eu3+ energy transfer. Journal of Fluorescence, 22 (2). pp. 745-752. ISSN 1053-0509

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Europium doped glass ceramics containing BaF2 nano-crystals have been prepared by using the controlled crystallization of melt-quenched glasses. X-ray diffraction and transmission electron microscopy have confirmed the presence of cubic BaF2 nano-crystalline phase in glass matrix in the ceramized samples. Incorporation of rare earth ions into the formed crystalline phase having low phonon energy of 346 cm-1 has been demonstrated from the emission spectra of Eu3+ ions showing the transitions from upper excitation states 5DJ (J = 1, 2, and 3) to ground states for the glass-ceramics samples. The presence of divalent europium ions in glass and glass-ceramics samples is confirmed from the dominant blue emission corresponding to its 5d-4f transition under an excitation of 300 nm. Increase in the reduction of trivalent europium (Eu3+) ions to divalent (Eu2+) with the extent of ceramization is explained by charge compensation model based on substitution defect mechanisms. Further, the phenomenon of energy transfer from Eu2+ to Eu3+ ion by radiative trapping or reabsorption is evidenced which increases with the degree of ceramization. For the first time, the reduction of Eu3+ to Eu2+ under normal air atmospheric condition has been observed in a BaF2 containing oxyfluoride glass-ceramics system.

Item Type: Article
Uncontrolled Keywords: Glasses, Transparent oxyfluoride glass ceramics, Optical probe, Eu-Luminescence
Subjects: Glass
Divisions: Glass
Depositing User: Mrs Chandana Patra
Date Deposited: 15 Nov 2011 12:01
Last Modified: 30 Jan 2013 12:17

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