Luminescence of Eu3+/Gd3+ co-doped silicate sol–gel powders.

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]