Studies on Thermal Migration of Eu Ion Doped into TiO2 Nanoparticles

概要

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The location of the Eu ion in the TiO2 lattice was investigated as a function of sintering temperature using X-ray photoelectron spectroscopy (XPS), to clarify the role of the Eu ion in TiO2 nanoparticles synthesized by the simple sol–gel method. The crystalline structure as well as the average crystallite size were evaluated using X-ray diffraction (XRD), and the direct observation of nanoparticles was carried out using atomic force microscopy (AFM). A model was proposed in which, in the as-synthesized gel state, the Eu ion occupies the core part of a nanoparticle, and with increasing sintering temperature, it migrates toward the particle shell to finally reach the surface at high sintering temperatures above 900 °C, at which sufficient thermal energy is provided to allow the Eu ion to migrate to the surface of the nanoparticles, resulting in the formation of Eu2Ti2O7 with a pyrochlore structure and an abrupt decrease in the photoluminescence (PL) intensity of the Eu ion.
2008-06-25