The actual occupancy of the two available cation sites by luminescent Eu3+ ions, in the cubic bixbyite-type structure of nanocrystalline sesquioxides, has been investigated by Eu-151 Mossbauer spectroscopy and magnetic susceptibility measurements. It was found that one fourth of the europium ions is in the more symmetric site C-3i and three fourths in the less symmetric site C-2; the distribution is random. In the series of the Eu-doped sesquioxides Sc2O3, Lu2O3, Y2O3 and Eu2O3, the covalency of the Eu-O bond and the Eu site distortion increase with the difference in ionic radii between europium and the cation of the host compound. The magnetic susceptibility has been analyzed as sum of the contributions of the free Eu3+ ion, of the crystal-field effect and of the exchange interaction between europium ions.
Distribution of Eu3+ dopant ions in C3i and C2 sites of the nanocrystalline Sc2O3:Eu phosphor
BETTINELLI, Marco Giovanni;SPEGHINI, Adolfo
2008-01-01
Abstract
The actual occupancy of the two available cation sites by luminescent Eu3+ ions, in the cubic bixbyite-type structure of nanocrystalline sesquioxides, has been investigated by Eu-151 Mossbauer spectroscopy and magnetic susceptibility measurements. It was found that one fourth of the europium ions is in the more symmetric site C-3i and three fourths in the less symmetric site C-2; the distribution is random. In the series of the Eu-doped sesquioxides Sc2O3, Lu2O3, Y2O3 and Eu2O3, the covalency of the Eu-O bond and the Eu site distortion increase with the difference in ionic radii between europium and the cation of the host compound. The magnetic susceptibility has been analyzed as sum of the contributions of the free Eu3+ ion, of the crystal-field effect and of the exchange interaction between europium ions.
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