Effects of reducing atmosphere on the luminescence of Eu3+-doped yttria-stabilized zirconia sensor layers in thermal barrier coatings

Abstract

The use of Eu3+-doped yttrium-stabilized zirconia (YSZ) as an embedded layer in thermal barrier coatings for luminescence temperature sensing has previously been demonstrated in air. In this work the effects of exposure to reducing atmospheres on the luminescence spectra and luminescence lifetime as a function of temperature are reported. No effect of reducing atmosphere, down to oxygen partial pressures() of <10-11 ppm, on either the Eu 3+ luminescence spectrum or the luminescence lifetime up to 900°C are seen although the overall luminescence intensity is decreased. The insensitivity of the temperature dependence of the luminescence lifetime to oxygen partial pressure indicates that Eu3+-doped YSZ based temperature sensors can be used with confidence in reducing as well as in air atmospheres. The results also suggest that the charge transfer mechanism responsible for the temperature dependence of the luminescence lifetime is unaffected by the oxygen vacancies introduced by reduction. © 2008 The American Ceramic Society.