Nanocomposite in the form of a porous matrix SiO2 with average pore size of 320 nm filled with barium titanate nanoparticles in paraelectric cubic phase was obtained. Shift of the stretching vibration of Si-O-Si to higher frequencies caused by increased strengthening of the network in the matrices has been observed. Also demonstrated that decrease in the intensity of the absorption relating to Si-O(H) stretching vibration relative to Si-O(-Si) stretching vibration. Raman scattering spectra demonstrate the presence of both a cubic and a tetragonal ferroelectric crystalline phase in the filler nanoparticles. Thus, the mechanical deformation of nanoparticles in the pores of the matrix can lead to a change in the crystalline phase of the filler. © 2020 Trans Tech Publications Ltd, Switzerland.

The work was funded by Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica-CONCYTEC according to agreement at Sub project 072–2018–FONDECYT–BM–IADT–AV.

Spherical titanium barium nanoparticles with an average size about 100 nm in the tetragonal crystal phase were obtained by peroxide synthesis. To prevent their agglomeration and reduce the toxic effect, the surface of nanoparticles was chemically modified with sodium oleate and chitosan. Influence of surface modification by these compounds on agglomeration of nanoparticles in aqueous solutions, their spectral features, as well as generation of the second optical harmonic were investigated.