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Title: Photoluminescence and cathodoluminescence of BaAl2O4:Eu2+ and undoped BaAl2O4: evidence for F-centres
Authors: den Engelsen, D
Fern, GR
Ireland, TG
Yang, F
Silver, J
Issue Date: 27-Jul-2020
Publisher: Optical Society of America
Citation: den Engelsen, D., Fern, G.R., Ireland, T.G., Yang, F. and Silver, J. (2020) 'Photoluminescence and cathodoluminescence of BaAl2O4:Eu2+ and undoped BaAl2O4: evidence for F-centres', Optical Materials Express, 2020, 10(8): 1962 - 1980. doi: 10.1364/OME.10.001962.
Abstract: © Copyright 2020 The Author(s). In this article the photoluminescence (PL) and cathodoluminescence (CL) of undoped BaAl2O4 and BaAl2O4 doped with 500 ppm and 3 mol% Eu2+ is described. The most important results from the CL measurements are: (1) Undoped BaAl2O4 manifested intrinsic CL at 460 nm, which increased at low temperature and did not change significantly upon exposure to the e-beam; (2) Doping BaAl2O4 with Eu2+ changed the character of the intrinsic luminescence band: it became more sensitive to temperature variations and the band experienced a blue shift to ∼425 nm; (3) electron beam (e-beam) exposure of Ba0.97Eu0.03Al2O4 at low temperature increased the 425 nm band strongly while the Eu2+ emission at ∼500 nm decreased by about 70%. The Eu2+ emission band was symmetric, indicating that BaAl2O4:Eu has changed to the P6322 phase upon e-beam exposure at low temperature; (4) We have identified the 460 nm band in undoped BaAl2O4 and the 425 nm band in BaAl2O4:Eu2+ with F-centre luminescence, corresponding to the F-centre emission in α-Al2O3. The evidence for the assignment of the 425 nm band in BaAl2O4:Eu2+ is the spectacular increase of the spectral radiance at 425 nm by e-beam exposure at 200 keV and low temperature. A preliminary model is presented that explains the results. The PL from BaAl2O4:Eu2+ quenched at the rather low temperature of 140°C; this observation is explained in terms of thermal ionization of the Eu2+ ion.
Other Identifiers: ORCID iD: Daniel den Engelsen; Terry G. Ireland
Appears in Collections:Wolfson Centre for Sustainable Materials Development and Processing
Dept of Mechanical and Aerospace Engineering Research Papers

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