The bismuth triborate (BiB 3 O 6 ; BIBO) single crystal has been studied by Brillouin and Raman spectroscopy. directions has been analyzed. The influence of birefringent and optical activity of BIBO crystal on some acoustic phonons has been discussed. The Raman spectra of the crystal in different scattering geometries have been recorded in the 50-1500 cm -1 spectral range at room temperature. The number and symmetry of Raman active modes was determined on the basis of site symmetry group analysis.

The aim of this article is to investigate the effect of nanoparticle clustering on the mobility of nanoparticles in nanocomposites, using spectroscopic methods (Brillouin and Raman). Special attention is paid to the effect of particle clustering on photocuring kinetics. The model system was poly(2-hydroxyethyl acrylate) filled with fumed nanosilica in concentration range encompassing the percolation threshold. Results obtained from Brillouin spectroscopy show substantial changes in the sound velocity and the attenuation coefficient with increasing filler content. The damping of acoustic waves reaches the maximum at the percolation threshold ($15 wt %), which is related to changes in the mechanism of acoustic wave propagation. The formation of the cocontinuous silica phase strongly affects the curing kinetics of the monomer/silica system: the polymerization rate is the highest at a silica content corresponding to the percolation threshold. These results correlate well with the results of AFM surface roughness analysis. V C 2013Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39895.

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In this paper we report the elastooptic constants pig of strontium 1an-thanum aluminate, SrLaΑlO4 and strontium lanthanum gallate SrLaGaO4 single crystals, which were determined at room temperature using TriIlouin scattering method. In order to investigate the elastooptic constants of SrLaAlO4 and SrLaGaO4 single crystals, a substitution method proposed by Cummins and Schoen, and developed by Nelson and Lax was used. The obtained results are also discussed in terms of the nature defects which might arise in these crystals during growth process.