Optical Absorption and EPR Studies on Gamma-Ray Irradiated RE3+-Doped Fluorophosphate Glasses
We have studied the effect of γ-ray irradiation on optical absorption, emission and decay characteristics of RE3+ (RE = Sm, Eu and Dy)-doped fluorophosphate glasses. Electron paramagnetic resonance (EPR) study confirms the POHC and PO3 EC defects induced in glasses by the γ-irradiation. The presence of induced defect centers significantly affects the optical and emission properties. The optical band gap values of the studied systems increased after the γ-ray irradiation. The phonon energy and electron–phonon coupling strength of Eu3+-doped fluorophosphate glass were determined from the phonon sideband analysis. The emission intensity of the RE3+ ions increased significantly after the γ-ray irradiation. The intensity parameter, R is the ratio of the intensities of the 5D0 → 7F2/5D0 → 7F1 transitions of Eu3+ ion and Y/B intensity parameter is the ratio of intensities of the 4F9/2 → 6H13∕2/4F9/2 → 6H15/2 transitions of Dy3+ ion reveal that the local environment around the RE3+ ion changed after the γ-ray irradiation in the present system. The lifetime of excited states of RE3+ ions decreased after the γ-ray irradiation due to the formation of defects induced by the γ-ray irradiation. The CIE color coordinates were determined before and after the γ-ray irradiation for the Dy3+-doped glass system.
KeywordsFluorophosphate glasses Gamma-ray irradiation Optical absorption and EPR spectroscopy
This work was partially supported by the New Growth Engine Industry Project of the Ministry of Trade, Industry and Energy, Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (No. 2013R1A1A2063250), and KEPCO Research Institute (KEPRI) and managed by KESRI (Project Number: KEPRI-16-23), South Korea. Dr. Ch. Basavapoornima is thankful to University Grants Commission, New Delhi, for the award of Post-Doctoral Fellowship for Women for the year of 2011–12 (F.15-1/2011–12/PDFWM-2011–12-OB-AND-9964 (SA-II), dt. 1-11-2013).
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