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Title: Mechanisms of optical losses in the {sup 5}D{sub 4} and {sup 5}D{sub 3} levels in Tb{sup 3+} doped low silica calcium aluminosilicate glasses

Trivalent Tb-doped materials exhibit strong emission in the green and weak emission in the UV-blue levels. Usually, this behavior is attributed to the cross relaxation (CR) process. In this paper, the luminescence properties of Tb{sup 3+}-doped low silica calcium aluminosilicate glasses are analyzed for UV (λ{sub exc} = 325 nm) and visible (488 nm) excitations. Under 325 nm excitation, the intensity of green luminescence increases proportionally to Tb{sup 3+} concentration. However, the blue luminescence intensity is strongly reduced with the increase of concentration from 0.5–15.0 wt. %. In the case of 488 nm excitation, a saturation behavior of the green emission is observed at intensities two orders of magnitude smaller than expected for bleaching of the ground state population. Using a rate equation model, we showed that this behavior can be explained by an excited state absorption cross section two orders of magnitude larger than the ground state absorption. The blue emission is much weaker than expected from our rate equations (325 nm and 488 nm excitation). We concluded that only the CR process cannot explain the overall feature of measured luminescence quenching in the wide range of Tb{sup 3+} concentrations. Cooperative upconversion from a pair of excited ions ({sup 5}D{sub 3}:{sup 5}D{sub 3} or {sup 5}D{sub 3}:{sup 5}D{submore » 4}) and other mechanisms involving upper lying states (4f5d, charge transfer, host matrix, defects, etc.) may play a significant role.« less
Authors:
; ; ;  [1] ; ; ;  [2]
  1. Instituto de Física de São Carlos, Universidade de São Paulo, P.O. Box 369,13560-970 São Carlos, SP (Brazil)
  2. Departamento de Física, Universidade Estadual de Maringá, Av. Colombo 5790, 87020-900 Maringá, PR (Brazil)
Publication Date:
OSTI Identifier:
22413030
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 5; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ABSORPTION; ALUMINIUM SILICATES; CALCIUM COMPOUNDS; CONCENTRATION RATIO; DOPED MATERIALS; EXCITATION; EXCITED STATES; GLASS; GROUND STATES; LUMINESCENCE; PHOTOLUMINESCENCE; QUENCHING; REACTION KINETICS; RELAXATION; SILICA; TERBIUM IONS; ULTRAVIOLET RADIATION; VISIBLE RADIATION