Eu-doped Y 2 O 3 phosphor films produced by electrostatic-assisted chemical vapor deposition
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Eu-doped Y2O3 phosphor films produced by electrostatic-assisted chemical vapor deposition K.L. Choya) Department of Materials, Imperial College of Science, Technology and Medicine, Prince Consort Road, London SW7 2BP, United Kingdom
J.P. Feist and A.L. Heyes Department of Mechanical Engineering, Imperial College of Science, Technology and Medicine, Prince Consort Road, London SW7 2BP, United Kingdom
B. Su Department of Materials, Imperial College of Science, Technology and Medicine, Prince Consort Road, London SW7 2BP, United Kingdom (Received 17 November 1998; accepted 23 March 1999)
Europium-doped yttrium oxide (Y2O3 :Eu) thermographic phosphor films were deposited on Ni-alloy substrates using a novel and cost-effective electrostatic-assisted chemical vapor deposition (EACVD) technique. The thermoluminescence properties were studied under irradiation by an ultraviolet laser. It was found that crystallized Y2O3 :Eu films could be deposited at a temperature as low as 550 °C. Annealing of the as-deposited films at higher temperatures (>1000 °C) improved the luminescence properties due to further crystallization processes. The correlation of the lifetime decay and temperature change of the films showed that the EACVD-deposited films are suitable for use in phosphor thermometry for high-temperature applications. I. INTRODUCTION
Y2O3 :Eu is one of a group of materials, known as thermographic phosphors, whose luminescent properties are temperature-sensitive and which can be used to measure surface temperatures by applying a thin coat of phosphor to the substrate surface and observing its luminescence when illuminated with ultraviolet light. Y2O3 :Eu shows sensitivity at relatively high temperatures and is, therefore, one of the phosphors which could potentially be used in the hostile high-temperature environments such as gas turbines.1–3 Current phosphor-based thermometry takes advantage of three different temperature dependent effects: observation of line shifts,4 intensity ratios,5 or lifetime decays of particular emission lines.1–3 The latter has been proven suitable for high-temperature applications with Y2O3 : Eu using the strong emission line at 611 nm whose lifetime follows an exponential decay, the time constant of which, decreases over the temperature range 550–1010 °C.1,3 It is essential to fabricate a reliable phosphor film onto turbine components for use in a hostile combustion environment. Several methods have been investigated for the fabrication of Y2O3 :Eu films. Chemical binders can be used to prepare phosphor paint and produce gooda)
Address all correspondence to this author. e-mail: [email protected] J. Mater. Res., Vol. 14, No. 7, Jul 1999
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quality films for use in a development test (not inservice) at temperatures up to around 1000 °C. Other techniques, such as chemical vapor deposition,6 pulsedlaser ablation,6 and physical vapor deposition (PVD) (e.g., radio frequency sputtering and electron-beam
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