The melt method is used for synthesizing monodispersed spherical silica nanoparticles Gd_ x -Si_ y O_ z :Eu^3+. The particle diameter is 450 nm, and the standard deviation does not exceed 5%. The nanoparticles have a line luminescence spectrum with a dominant band at 614 nm. The effect of a constant magnetic field up to 15 T on the intensity and shape of the luminescence spectra of Eu^3+ ions is studied. It is shown that the obtained material has a stable photoluminescence, the intensity of which does not depend on the magnetic field in the entire studied range. The synthesized nanoparticles Gd_ x Si_ y O_ z : Eu^3+ are promising for use as a contrast agent for magnetic resonance tomography and luminescent marker.

Nanocomposite thermoelectrics based on Bi_0.45Sb_1.55Te_2.985 solid solution of p -type conductivity are fabricated by the hot pressing of nanopowders of this solid solution with the addition of SiO_2 microparticles. Investigations of the thermoelectric properties show that the thermoelectric power of the nanocomposites increases in a wide temperature range of 80–420 K, while the thermal conductivity considerably decreases at 80–320 K, which, despite a decrease in the electrical conductivity, leads to an increase in the thermoelectric efficiency in the nanostructured material without the SiO_2 addition by almost 50% (at 300 K). When adding SiO_2, the efficiency decreases. The initial thermoelectric fabricated without nanostructuring, in which the maximal thermoelectric figure of merit ZT = 1 at 390 K, is most efficient at temperatures above 350 K.