Investigation in the VUV range of the excitation efficiency of the Tb3+ ion luminescence in Y3 (Alx, Gay)5O12 host lattices
1995; Elsevier BV; Volume: 4; Issue: 6 Linguagem: Inglês
10.1016/0925-3467(95)00024-0
ISSN1873-1252
AutoresAlexandre Mayolet, W. Zhang, E. Simoni, J.C. Krupa, Patrick Martin,
Tópico(s)Lanthanide and Transition Metal Complexes
ResumoVUV excitation spectra of the visible luminescence of Tb3+ activated Y3(Alx, Gay)5O12 compounds and their diffuse reflectance spectra are presented. The crystal field strength, the absorption threshold of the matrix and the external quantum efficiency (Qext) associated with the different excitation mechanisms (4f8 → 4f7 5d transitions in the activator or interband transitions in the host) decrease when the gallium concentration increases. Such variations are ascribed to an increase of the oxidizing character of the host matrix along with the gallium concentration. The decrease of the external quantum efficiency (Qext) is discussed in terms of a trivalent rare-earth ion (RE3+) configurational coordinate model and related to the intervention of the photoionized state [RE3+ → RE4+ + e−]. The non radiative relaxation rate increases when this state is stabilized.affd
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