Nanosized MnFe2O4 phase with diameters in the range 13.7 to 100 nm were produced by calcination and sintering treatments in the system zNb2O5 · (50 – z)MnO · 50Fe2O3 with z having values between 0 and 20. Nb5+ ions are believed to give rise to vacancies in the Mn2+ sites, which break up the coupling of ferrimagnetically active oxygen polyhedra. The Curie temperature decreases as the size of the MnFe2O4 phase is reduced. This is explained on the basis of a decrease in the number of exchange pairs of the type Mn2+–Fe3+. The coercivity increases with a decrease in the size of the ferrimagnetic phase. This is believed to arise due to a decrease in saturation magnetization as the size of the MnFeO4 phase is reduced.

Composites containing micron-sized lead zirconate titanate and nanometer-sized lead sulfide in a glass matrix were prepared using a sol-gel technique. The PbS size ranged from 3.5 to 15.3 nm. It was possible to pole some of these nanocomposites. The measured values of saturation polarization, remanent polarization, and coercive field showed an increase as the PbS particle size was enhanced. The composites exhibited improvement in the piezoelectric and pyroelectric behavior as compared to that of the base glass-ceramic.

Glasses in the NiO–TiO2 system in the composition range 15 to 25 mol% of NiO have been synthesized by the sol-gel technique by heat treatment of the precursor sol at 500°C. The glass structure is built up by crosslinking of two units, namely TiO6 octahedron and NiO3 triangle. Glassy structure is confirmed at a microscopic level by scanning electron microscopy. An increase in the values of peak-to-peak width of electron paramagnetic resonance with increasing concentration of Ni2+ is attributed to an enhanced interaction between neighboring paramagnetic Ni2+ ions.

Sol-gel-derived films containing BaTiO3 crystallites have been grown on suitable substrates using a precursor composition in the system Li2O-BaO-TiO2. Silver particles of diameters in the range 4.9 to 16.2 nm have been synthesized within these films by ion exchange and reduction technique. Electrical resistivities are found to vary from ∼102 to 105 ohm-cm, depending on the silver particle diameter. A low activation energy, approximately a few millielectron volts, is found to characterize the electrical properties of most of the samples. A quantum size effect is invoked to explain the results.