Quenching of cathodoluminescence from Eu3+-doped La2O2S

Quenching of the cathodoluminescent (CL) efficiency of La2O2S:Eu3+ prepared by combustion reaction was investigated by measuring the temporal dependence of the CL intensities. While the emission intensity corresponding to the 5D0⇒7F2 electronic transition of Eu3+ did not change at a low current density (e.g., 65 μA/cm2), it decayed over the first 5 s of irradiation at a high current density (e.g., 500 μA/cm2). In addition, the difference between the initial and steady-state emission intensities increased as the current density increased. Based on thermal quenching data for the 5D0⇒7F2 transition, the quenching observed at high current densities was only partially explained by electron-beam heating. In addition to changes in intensity, the ratio of the CL intensities from the 5D1 transition (5D1⇒7F3) and the 5D0 transition (5D0⇒7F2) (designated 5D1/5D0) also decreased with increasing current density during the first ∼5 s of electron irradiation. Based upon measurement of the Auger electron peak energies, i...