Tb3+/Eu3+ co-doped silica xerogels prepared via low-temperature sol-gel method and their luminescence properties

Silica xerogels doubly-doped with Eu3+ and Tb3+ ions were prepared via low-temperature sol-gel method. The structural properties were determined based on X-ray diffraction analysis. The optical properties were studied based on excitation and emission spectra as well as luminescence decay analysis and the Tb3+ → Eu3+ energy transfer was registered. Upon direct excitation of Tb3+ ions the characteristic transitions from the 5D4 state of Tb3+ and from the 5D0 state of Eu3+ were registered. This is a direct proof that energy transfer from Tb3+ to Eu3+ in silica xerogels was occurred. Furthermore, the luminescence decay analysis from the 5D0 excited states of Eu3+ upon excitation of Tb3+ at λexc = 351 nm wavelength were also carried out. The luminescence lifetime from the 5D0 state of Eu3+ after excitation at 351 nm is long-lived in comparison to excitation at 393 nm and increased by 24%.