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Nanoparticles of GdVO4 doped with Eu3+ and core/shell of GdVO4:Eu3+/GdVO4 are prepared by urea hydrolysis method using ethylene glycol as capping agent as well as reaction medium at 130 °C. Unit cell volume increases when GdVO4 is doped with Eu3+ indicating the substitution of Gd3+ lattice sites by Eu3+. From luminescence study, it is confirmed that there is no particle size effect on emission positions of Eu3+. Optimum luminescence intensity is found to be in 5–10 at. % Eu3+. Above these concentrations, luminescence intensity decreases due to concentration quenching effect. There is an enhancement in luminescence intensity of core/shell nanoparticles. This has been attributed to the reduction in surface inhomogenities of Eu3+ surroundings by bonding to GdVO4 shell. The lifetime for D50 level increases with annealing and core/shell formation.

Sn O 2 : Eu 3 + nanoparticles uniformly dispersed in TiO2 matrix were prepared at 185°C in ethylene glycol. Unlike in SnO2:Eu3+, significant improvement in the exciton mediated energy transfer between SnO2 and Eu3+ ions was observed when SnO2:Eu3+ nanoparticles are dispersed in TiO2 matrix, and this is attributed to effective shielding of surface Eu3+ ions present in SnO2:Eu3+ nanoparticles from the vibrations of stabilizing ligand by TiO2 matrix. Annealing the samples at high temperatures leads to formation of Sn1−xTixO2, without significantly affecting the energy transfer process between Eu3+ ions and semiconductor host.

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Indium oxide and europium/dysprosium doped indium oxide nanoparticles were prepared using a sonochemical technique where indium ethoxide was used as a precursor. The obtained indium oxide nanoparticles were characterized using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) techniques. The band gaps of the particles were estimated using diffuse reflectance spectroscopy. With change in size of particles from 8 to 14 nm, the band gap varied between 4.11 and 3.79 eV. The photoluminescence (PL) spectra of In 2 O 3 nanoparticles showed peaks in visible region characteristic of shallow traps present within the nanoparticles. Weak luminescence was observed in europiumdoped indium oxide nanoparticles,

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