Abstract
Rare-earth (Pr3+, Tb3+, Er3+) doped silica xerogels were studied by x-ray absorption spectroscopy and x-ray diffraction. A change of the local environment around rare-earth ions upon xerogel densification at 900–950°C and co-doping with aluminum ions was determined from the rare-earths L3-edge EXAFS signals. The densification process induces a decrease of the coordination number and a compression and deformation of the first coordination shell, composed of oxygen atoms. The second coordination shell, composed of silicon and/or aluminum ions, also experiences some modification, which is attributed mainly to a shortening of the shell radius. No evidence of clustering of rare-earth ions upon densification was observed. X-ray diffraction data on Tb-doped gels confirm the EXAFS results.
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Rocca, F., Armellini, C., Ferrari, M. et al. X-Ray Absorption and Diffraction Studies of Pr3+, Tb3+ and Er3+-Activated Silica Gels. Journal of Sol-Gel Science and Technology 26, 267–271 (2003). https://doi.org/10.1023/A:1020715619229
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DOI: https://doi.org/10.1023/A:1020715619229