Effects of electron beam current density and temperature on peak height ratios Dj/D0 for cathodoluminescence of Ln2O2S:Eu |
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Authors: | Jungsik Bang Billie Abrams |
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Affiliation: | a Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611-6400, USA b Department of Materials Science and Engineering, Hongik University, 72-1 Sangsu-Dong, Mapo-Gu, Seoul 121-791, Republic of Korea c Sandia National Laboratories, P.O. Box 5800-1421, Albuquerque, NM 87185, USA |
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Abstract: | The change in the initial and steady state (∼0 and 5 s after initiation of electron beam irradiation) peak heights from the 5D2⇒7F3, 5D1⇒7F3 and 5D0⇒7F2 cathodoluminescent transitions from Eu3+ have been studied for Ln2O2S:Eu3+ (Ln=La, Gd) phosphors. Specifically, the intensity ratio of these transitions, designated as 5D1/5D0, increased and then decreased for both La2O2S:Eu3+ (0.1 mole%) and Gd2O2S:Eu3+ (0.4 mole%), as the current density was changed from 10 towards a 1000 μA/cm2. These effects were shown to be consistent with feeding from the higher 5D2 excited state to the lower energy 5D1 excited state, resulting in an increase of the 5D1/5D0 ratio at low current densities. At higher current densities, energy was funneled from the 5D1-5D0 states, resulting in a decrease of the 5D1/5D0 ratio. These effects of feeding versus funneling were dependent on both the Eu3+ concentration and current density, and changed with time (i.e., approached a steady state after ∼5 s) due to increased activator interactions from induced internal electric fields. The magnitude of thermal quenching versus interaction quenching was investigated using changes of the peak height ratios of 5D2/5D0 and 5D1/5D0. |
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Keywords: | Cathodoluminescent Ln2O2S:Eu3+ 5D1/5D0 Current density Thermal quenching |
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