Spectroscopic Properties of Nanophase Eu-Doped ZrO₂ and Its Potential Application for Fast Temperature Sensing Under Extreme Conditions

Abstract

Luminescent nanophase europium-doped ZrO2 precursors are subjected to pyroprobe heating with nominal heating rates of 20 000 °C/s for 1 and 10 s to various temperatures. When heated above the crystallization temperature, the material forms tetragonal and monoclinic polymorphs. Optical spectroscopy is used to measure the excitation spectra, fluorescence spectra, and fluorescence lifetimes of the heated samples. These optical signatures are evaluated for their potential as temperature indicators for short heating events. The fluorescence lifetimes and the intensity ratio of two fluorescence peaks appear to be promising temperature indicators. The fluorescence intensity ratio of two peaks at about 591 and 592 nm of the tetragonal polymorph decreases linearly with temperature and the peak position increases linearly with temperature between about 800 and 1300 K. The fluorescence lifetimes of both polymorphs increase with temperature. As the temperature reaches about 1000 K for the tetragonal phase and 1200 K for the monoclinic phase, the fluorescence lifetime starts to decrease again.