| Summary: | 碩士 === 國立東華大學 === 物理學系 === 99 === The Bi2Sr1-xTa2O9: Eux3+ orange-red phosphors were prepared by solid-state reaction. Only Bi2SrTa2O9 diffraction peaks were found by the X-ray power diffraction (XRD). The emission properties of the Bi2Sr1-xTa2O9: Eux3+ phosphors were measured by photoluminescence at the wave length of 353 nm. Three main peaks at 579, 590, 616 nm were found in the photoluminescence spectra which can be attributed to the transition of 5D0-7DJ (J=0-2) of Eu3+. Their electronic properties are critical issues yet to be understood. In this study, X-ray absorption (XAS) and emission (XES) spectroscopy are utilized to examine the electronic structure of the Eu3+-doped Bi2SrTa2O9 system. While no significant change in the electronic structure is observed around the Bi and Ta sites, variation around the Eu and Sr atoms is observed, along with even more significant changes in the O 2p states in the conduction band. The presence of the newly formed hole states distributed over the O 2p states in the conduction band is strongly correlated with the emission intensity. The results and analyses demonstrate that Eu can be introduced to tailor the Eu-O hybridized states within the conduction band, suggesting that Eu is critically involved in light emission in the these UV-induced orange-red emitting LED materials.
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