Doped Oxides for High-Temperature Luminescence and Lifetime Thermometry

The measurement of high temperatures in oxides and oxide-based structures in practical applications often presents challenges including steep thermal gradients, the presence of flames or chemically aggressive environments, and the transparency or translucency of most oxides. For turbine engines, oxide coatings are of great commercial importance, and the rapid motion of parts prohibits contact thermometry. Luminescence thermometry offers a number of advantages for measuring temperature in such systems and has been the subject of ongoing study for many years. Recent work on rare-earth-doped thermal barrier coatings, environmental barrier coatings, and related oxides has demonstrated the feasibility of luminescence thermometry to temperatures well in excess of 1000 degrees C. The luminescent properties of these materials and the analytical techniques used to extract reproducible temperature measurements from the measured luminescence are reviewed.