Nanocomposites and nanomaterials 

Luminescent properties of opal and opal - active dielectric nanocomposites, infiltrated by C6H9EuO6xH2O 
Moiseyenko V.N., Golochalov D.O., Gavrilyak V.R. 
Physics, Electronics and Computer Systems Department, Oles Honchar Dnipro National University. Prospect Gagarina, 72, Dnipro-49010, Ukraine. 
E-mail: vnmois@ukr.net 

The photoluminescence spectra of rare-earth compounds have been the subject of extensive studies [1], which have suggested that europium (Eu3+) and terbium (Tb3+) are promising materials for filling opal pores. 
We obtained photoluminescence spectra of the (111) growth surface of an opal photonic crystal as well as the opal - active dielectric nanocomposites whose pores were filled with europium (III) acetate hydrate (C6H9EuO6xH2O). The regularities of the changes in the characteristics of the europium (III) acetate hydrate photoluminescence spectra in the pores of thin-film and bulk opals, as well as the opal - active dielectric nanocomposites, were studied. Infiltration was carried out by dipping the opals into a water solution of C6H9EuO6 x H2O (99.9% trace metals basis). The excitation of the samples was carried out in the "reflection" geometry from the (111) plane by the radiation of a semiconductor laser with λex = 405 nm. For measurements a double monochromator of the DFS-12 spectrometer was used. 
In the measured spectra the radiative transitions in the energy spectrum of Eu3+ 5D0 → 7F0, 7F1, and 7F2 were observed at wavelength 580 nm, 592 nm and 619 nm respectively. The displacement of the photoluminescence spectra of europium (III) acetate hydrate in the pores of opal and nanocomposites in the long-wave region at 3.5 nm is revealed. The dependence of the intensities of the bands in the spectrum on the position of the stop-band is established. An increase (in 5 times) of the luminescence intensities for the bands located at the boundary of the thin-film opal stop-band was observed. The decrease in the photoluminescence spectra intensity of europium (III) acetate hydrate in the pores of certain nanocomposites (opal - Bi2TeO5, opal - NaBi(MoO4)2, opal - TeO2) concerning its spectra in the pores of opal was revealed. At the same time an increase of the intensity of all bands in 1.5 times for the nanocomposite opal - Bi12SiO20 was observed. 

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