University of Khartoum

5D3→7FJ emission of Tb doped sol–gel silica

5D3→7FJ emission of Tb doped sol–gel silica

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Title: 5D3→7FJ emission of Tb doped sol–gel silica
Author: Seed Ahmed, Hassan Abdelhalim Abdellhah
Abstract: Amorphous silica samples doped with 0.1 and 1 mol% of terbium (Tb) were synthesized by the sol–gel method. In addition to the green light associated with 5D4-7FJ transitions of Tb3þ, the sample containing 0.1 mol% also emitted blue light as a result of 5D3-7FJ transitions during photoluminescence (PL) measurements. As a result of concentration quenching this blue emission was not observed for the samples doped with the higher concentration (1 mol%). However the blue 5D3 -7FJ emission was observed in the 1 mol% doped samples during cathodoluminescence (CL) measurements. Since a rough calculation indicated that the excitation rate in the CL system where the blue emission is observed may be similar to a laser PL system under conditions where the blue emission is not observed, the difference is attributed to the nature of the excitation sources. It is suggested that during the CL excitation incident electrons can reduce non-luminescent Tb4þ ions in the silica, substituting for Si4þ ions, to the excited (Tb3þ)* state and that these are responsible for the blue emission, which does not occur during PL excitation
URI: http://khartoumspace.uofk.edu/123456789/21567


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