Effect of long term, high temperature aging on luminescence from Eu-doped YSZ thermal barrier coatings

The use of the luminescence from europium doped yttria-stabilized zirconia thermal barrier coatings for non-contact thermometry has been previously studied up to 850 °C [Choy, K.L. et al., Surface Engineering, 16 [6] (2000) 496] and 1150 °C [M.M. Gentleman and D.R. Clarke, Surface and Coatings Technology, 188–189 (2004) 93]. In this contribution we examine the effect of long-term, high temperature aging and martensitic phase transformation on both the details of the luminescence spectrum and the temperature-dependent lifetime of the luminescence. It is found that even after prolonged aging, the wavelength of the 5D0 → 7F2 emission peak shifts only very slightly with increasing percentage of transformation to the monoclinic phase. Preliminary data suggests that the effect on the decay lifetime up to 1150 °C is very slight, expressed in a slight shift of the onset of thermal quenching to lower temperatures; the slope of the characteristic decay time-constant versus temperature appears relatively unaffected.