Dy3+:Al2O3 and (Dy3++Cr3+): Al2O3 Films for Temperature Sensor Applications Derived by Thermal CVD and Sol-Gel Techniques

Abstract

Optical surface temperature measurements can be accomplished using thermographic phosphors (TP). These TPs can be deposited using CVD or sol-gel techniques, both techniques not being used often for this purpose. In this work dysprosium doped alumina films α-Al2O3:Dy and alumina films co-doped with dysprosium and chromium α-Al2O3:M (M:=Dy3+, Cr3+) were prepared by both techniques for TP applications and the results were compared. Diketonates of Dy, Cr and Al were used for film preparation. The phosphorescence decay lifetime of the Dy3+-transitions show strong temperature dependency in a temperature range from 1100 to 1500 K while the phosphorescence lifetime of Cr3+:Al2O3 (ruby) varies sufficiently in the temperature range from 298 up to 800 K. Thus, Cr3+-doped Al2O3 films are useful as thermographic phosphor coating for lower temperatures than Dy3+-doped films, while, co-doped films are temperature sensitive in the full temperature range from 298 up to 1500 K.