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Influence of oxygen doping and hydration on photostimulated luminescence of CsBr and CsBr:Eu2+

Appleby, G. A. and Kroeber, P. and Zimmermann, J. and Seggern, H. von (2011):
Influence of oxygen doping and hydration on photostimulated luminescence of CsBr and CsBr:Eu2+.
109, In: Journal of Applied Physics, (7), pp. 073510. AIP Publishing LLC, ISSN 00218979,
[Article]

Abstract

Powdered samples of CsBr:O2− and CsBr:Eu2+,O2− with oxygen concentrations ranging from 0.01 to 5.00 mol% have been synthesized and are shown to have photostimulated luminescence (PSL) properties which are strongly influenced by the oxygen concentration. In europium free CsBr:O2−, it was found that weak PSL emission at 460 nm arises from oxygen impurities while with oxygen concentrations higher than 0.05 mol% the emission shifts to the 379 nm emission of the CsBr matrix, which is attributed to the nonexcitability of oxygen agglomerates. The F-center concentration in CsBr:O2− is observed to increase with oxygen concentration, due to an increase in Br-vacancies as charge compensation centers for the O2− ions. In all CsBr:Eu2+ samples studied, intense PSL emission arises only following room temperature hydration in an atmosphere of 99% relative humidity, and it is concluded that the presence of water molecules is essential for the PSL in CsBr:Eu2+. In CsBr:Eu2+,O2− this enhancement effect of PSL intensity is reduced as the oxygen concentration increases above 0.05 mol% due to competition between the Eu2+ and O2− luminescence centers. It was found that the effects of hydration can be partially reversed following exposure to a vacuum while the material is rendered completely PSL inactive following thermal annealing up to 600 °C which is caused by agglomeration of the highly mobile Eu2+ ions and subsequent loss of Eu2+ luminescence.

Item Type: Article
Erschienen: 2011
Creators: Appleby, G. A. and Kroeber, P. and Zimmermann, J. and Seggern, H. von
Title: Influence of oxygen doping and hydration on photostimulated luminescence of CsBr and CsBr:Eu2+
Language: English
Abstract:

Powdered samples of CsBr:O2− and CsBr:Eu2+,O2− with oxygen concentrations ranging from 0.01 to 5.00 mol% have been synthesized and are shown to have photostimulated luminescence (PSL) properties which are strongly influenced by the oxygen concentration. In europium free CsBr:O2−, it was found that weak PSL emission at 460 nm arises from oxygen impurities while with oxygen concentrations higher than 0.05 mol% the emission shifts to the 379 nm emission of the CsBr matrix, which is attributed to the nonexcitability of oxygen agglomerates. The F-center concentration in CsBr:O2− is observed to increase with oxygen concentration, due to an increase in Br-vacancies as charge compensation centers for the O2− ions. In all CsBr:Eu2+ samples studied, intense PSL emission arises only following room temperature hydration in an atmosphere of 99% relative humidity, and it is concluded that the presence of water molecules is essential for the PSL in CsBr:Eu2+. In CsBr:Eu2+,O2− this enhancement effect of PSL intensity is reduced as the oxygen concentration increases above 0.05 mol% due to competition between the Eu2+ and O2− luminescence centers. It was found that the effects of hydration can be partially reversed following exposure to a vacuum while the material is rendered completely PSL inactive following thermal annealing up to 600 °C which is caused by agglomeration of the highly mobile Eu2+ ions and subsequent loss of Eu2+ luminescence.

Journal or Publication Title: Journal of Applied Physics
Volume: 109
Number: 7
Publisher: AIP Publishing LLC
Uncontrolled Keywords: annealing, caesium compounds, charge compensation, doping profiles, europium, F-centres, impurities, oxygen, photoluminescence, powders, solvation, vacancies (crystal)
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Electronic Materials
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 14 Oct 2013 09:18
Official URL: http://dx.doi.org/10.1063/1.3569745
Identification Number: doi:10.1063/1.3569745
Funders: The authors would like to acknowledge financial support from the Deutsche Forschungsgemeinschaft (DFG).
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