Photoluminescence of Pr3+, Sm3+ and Dy3+: SiO2-Al2O3-LiF-GdF3 glass ceramics and Sm3+, Dy3+: GeO2-B2O3-ZnO-LaF3 glasses

In this paper, we present the absorption and photoluminescence properties of Pr3+, Sm3+ and Dy3+-doped transparent oxyfluoride alumino-silicate glass ceramics and Sm3+ and Dy3+-doped oxyfluoride germanate glasses. The X-ray diffraction (XRD) and differential thermal analysis (DTA) profiles of these glasses have been carried out, to confirm their structure and thermal stability. These glasses or glass ceramics have shown strong emission and absorption bands in visible and near-infrared (NIR) region. From the measured absorption spectra, Judd-Ofelt (J-O) intensity parameters (Ω2, Ω4 and Ω6) have been calculated for all the studied ions. Compared to Pr3+, Sm3+ and Dy3+ doped glasses, their respective glass ceramics have shown stronger emissions due to LiGdF4 crystalline phase in alumino-silicate glass ceramics. For Pr3+ doped glass and glass ceramic, emission bands centered at 527 nm(3P0→3H5), 610 nm(3P0→3H6), 640 nm(3P0→3F2), 678 nm(3P1→3F3), 702 nm(3P0→3F3) and 721 nm(3P0→3F4) have been observed with 445 nm(3H4→3P2) excitation wavelength. Of them, 640 nm(3P0→3F2) has shown bright red emission. Emission bands of 4G5/2→6H5/2 (562 nm), 4G5/2→6H7/2 (598 nm), 4G5/2→6H9/2 (644 nm) and 706 nm(4G5/2→6H11/2) for the Sm3+: glass and glass ceramic, with excitation at 6H5/2→4F7/2 (402 nm) have been recorded. Of them, 4G5/2→6H7/2 (598 nm) has shown a bright orange emission. With regard to the Dy3+: glass and glass ceramic, a bright fluorescent yellow emission at 576 nm(4F9/2→6H13/2) and blue emission at 485 nm(4F9/2→6H15/2) have been observed, apart from 4F9/2→6H11/2 (662 nm) emission transition for glass ceramic with an excitation at 388 nm(6H15/2→4I13/2+4F7/2) wavelength. For germanate glasses, emission bands of 4G5/2→6H5/2 (564 nm), 4G5/2→6H7/2 (601 nm), 4G5/2→6H9/2 (644 nm) and 705 nm(4G5/2→6H11/2) for the Sm3+: glass, with an excitation at 6H5/2→4F7/2 (401 nm) have been recorded. Of them, 4G5/2→6H7/2 (601 nm) has shown a bright orange emission. With regard to the Dy3+: glass, a bright fluorescent yellow emission at 576 nm(4F9/2→6H13/2) and blue emission at 482 nm(4F9/2→6H15/2) have been observed, apart from 4F9/2→6H11/2 (661 nm) emission transition with an excitation at 386 nm(6H15/2→4I13/2+4F7/2) wavelength. The stimulated emission cross-sections of all the emission bands of Pr3+, Sm3+ and Dy3+: glasses and glass ceramics have been computed based on their measured full-width at half maxima (FWHM, Δλ) and measured lifetimes (τm).