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|Title:||<smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="metricconverter"> Luminescence efficiency of Eu<sup>+3 in </sup>Y<sub>2</sub>O<sub>3</sub>: The effect of reduction of particle size and incorporation of trace hetero-cations in the Y<sub>2</sub>O<sub>3</sub> lattice </smarttagtype>|
|Keywords:||Y<sub>2</sub>O<sub>3</sub>:Eu<sup>+3 </sup>red phosphor|
|Abstract:||The effect of incorporation of trace (Al<sup>+3</sup>, B<sup>+3</sup>) in the Y<sub>2</sub>O<sub>3 </sub>lattice on the luminescence efficiency of<b> </b>Y<sub>2</sub>O<sub>3</sub>:Eu<sup>+3 </sup>red phosphor has been investigated. It is observed that such incorporation causes an enhancement of <sup>5</sup><i>D</i><sub>0</sub>→<sup>7</sup><i>F</i><sub>2</sub> red luminescence efficiency as well as the associated excitation efficiency of Eu<sup>+3</sup>. It is concluded that there occurs a change in the polarity of the host rather than the site symmetry of Eu<sup>+3 </sup>due to incorporation of the hetero cations. Calculation of the Judd-Ofelt parameters gives similar results. In another study, to observe the effect of reduction of particle size on the luminescence efficiency of the Y<sub>2</sub>O<sub>3</sub>:Eu<sup>+3</sup>, the change in luminescence efficiency of the phosphor with the reduction particle size and the stability of the different efficiencies with the elapse of time have been investigated. The samples with particle size below 100 nm showed a significant loss in luminescence efficiency and a change in their excitation profile with time. IR studies showed that although the freshly prepared samples were almost free from contaminated water, on ageing in air at room temperature, they absorb the latter. A phenomenon of hydration induced coupling of the excitonic state of Y<sub>2</sub>O<sub>3</sub> with one of its F<sub>u</sub> modes, has been detected in the case of the aged samples which susequently introduces newer non-radiative channels in the system causing a decrease in the luminescence efficiency of the phosphor. Because of larger surface to volume ratio, the effect is most pronounced in nanocrystalline samples.|
|ISSN:||0975-1041 (Online); 0019-5596 (Print)|
|Appears in Collections:||IJPAP Vol.47(11) [November 2009]|
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