Er,Yb:ZrO2/Eu:Y2O3 core/shell assemblies as potential temperature sensors in explosions

Abstract

We have recently demonstrated the use of nanophase Eu:Y2O3 and Eu:ZrO2 as temperature sensors in explosions. Our previous measurements have shown that each of these materials is suitable for a certain temperature range – Eu:Y2O3 covers the range from about 500 K to about 900 K, and Eu:ZrO2 the range from about 800 K to about 1300 K. In order to have one material that can cover a wider range of temperatures, we have prepared core/shell assemblies of these host materials with different dopants. Here we report on the synthesis and characterization of core/shell assemblies consisting of Er,Yb:ZrO2 cores and Eu:Y2O3 shells. The Er,Yb:ZrO2 core is synthesized via forced hydrolysis and the Eu:Y2O3 shell is synthesized via homogeneous precipitation. Subsequently, these core/shell assemblies are heated for 3 h in a furnace and for 10 s by a pyroprobe at various temperatures. Temperature-induced phase changes in the materials lead to changes in the optical spectra, which can then be correlated with temperature. The Er,Yb:ZrO2 core emits upconverted light in the red and green spectral range when excited with 970 nm, while the Eu:Y2O3 shell emits in the red spectral range when excited with 532 nm. These spectra can be measured separately allowing us to determine temperatures over a wide range.