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Temperature-dependent up-conversion luminescence spectra of Er 3+ in lead-free germanate glass have been examined under 800 nm and 980 nm diode laser excitation. Green up-conversion luminescence spectra measured in the 500–580 nm ranges correspond to transitions originating from thermally coupled 2 H 11/2 and 4 S 3/2 levels to 4 I 15/2 ground level of Er 3+ . The relative emission band intensities of 2 H 11/2 → 4 I 15/2 and 4 S 3/2 → 4 I 15/2 transitions of Er 3+ are changed with temperature. The rate of fluorescence intensity ratio varying with temperature was calculated for glass sample excited at 800 nm and 980 nm, respectively. The maximum temperature sensitivity is nearly 20% higher for glass sample pumped at 980 nm than 800 nm. [ABSTRACT FROM AUTHOR]

Abstract: Ln-doped oxychloride lead borate glasses were studied using luminescence spectroscopy. Rare earth ions were limited to trivalent Pr3+, Tm3+, Eu3+ and Er3+. Luminescence spectra were registered, which correspond to 3P0–3H4 and 1D2–3H4 transitions of Pr3+, 1G4–3H5 and 1G4–3F4 transitions of Tm3+, 5D0–7F J (J=0, 1, 2, 3, 4) transitions of Eu3+ and 4S3/2,2H11/2–4I15/2 and 4I13/2–4I15/2 transitions of Er3+. Luminescence decays from the excited states of Ln3+ ions were analyzed in detail. The experimental results indicate that relatively high phonon energy of the host gives important contribution to the excited state relaxation of rare earth ions. [Copyright &y& Elsevier]

Eu 3+ /Gd 3+ co-doped silicate sol–gel powders have been successfully obtained. The effect of high concentration of gadolinium ions on visible emission of europium ions in prepared materials has been studied under different excitation wavelengths. Spectroscopic properties of Eu 3+ and Gd 3+ ions in prepared powders were determined based on excitation and emission measurements as well as luminescence decay analysis. In the visible spectral range the observed emission bands correspond to transitions of trivalent Eu 3+ and Gd 3+ ions. The changes of excitation mechanism of optically active dopants significantly affect the increase of luminescence intensities. The luminescence lifetime for the 5 D 0 level of Eu 3+ ions in examined samples upon excitation at λ exc =273 nm ( 8 S 7/2 → 6 I J transition of Gd 3+ ) is about 12 times longer in comparison to excitation at λ exc =393 nm ( 7 F 0 → 5 L 6 transition of Eu 3+ ). The luminescence intensity coefficient R (Eu 3+ ) was also calculated, and it was found that ratio of the intensity of red to orange emission depends on the excitation wavelength. Based on determined spectroscopic parameters the energy transfer process from Gd 3+ to Eu 3+ ions was confirmed. [ABSTRACT FROM AUTHOR]