No abstract

The effect of oxygen partial pressure on the phosphorescence of Eu x Y 0.08-x Zr 0.92 O 1. 96 and Dy x Y 0.08-x Zr 0.92 O 1.96 (x = 0.001, 0.005, 0.01, 0.02, 0.05) phosphors was investigated and compared to explore the Ln 3+ (Ln 3+ = Eu 3+ , Dy 3+ ) concentration effect on oxygen quenching using a lifetime-based measurement system equipped with a heatable and pressure controllable chamber. The phosphorescence lifetimes of these two series of phosphors were found to be sensitive to the oxygen partial pressure in high-temperature environments. Surprisingly, the oxygen sensitivity of Dy x Y 0.08-x Zr 0.92 O 1.96 phosphors markedly increases as the Dy 3+ concentration increases, while that of Eu x Y 0.08-x Zr 0.92 O 1.96 phosphors remains nearly constant.Further analysis shows that the oxygen quenching phenomenon is attributable to an oxygen vacancy-induced non-radiative decay reduction. However, the mechanisms of non-radiative decay affected by oxygen vacancies differ, with a charge transfer state (CTS) transition mechanism in Eu x Y 0.08-x Zr 0.92 O 1.96 and a crossrelaxation mechanism in Dy x Y 0.08-x Zr 0.92 O 1.96 phosphors. The CTS measured from the excitation spectrum is found to be independent of the Eu 3+ concentration. In contrast, cross-relaxation is closely related to the Dy 3+ concentration, as demonstrated by the concentration-quenching behaviours of the phosphorescence intensities and lifetimes, and the non-exponential decay curves. The present research was expected to shed light on the development and optimization of oxygen/pressure sensors for high-temperature service.