| Abstract
| - The sol−emulsion−gel method is used for the preparation of Eu2O3-doped and -coated TiO2 nanocrystals.Here, we report the control of the crystal phase composition and crystallite size as a function of the temperatureof heating and surface coating. A significantly higher anatase phase (100%) has been obtained at 800 °Cheated sample, and this anatase phase is stable up to 22 nm size. Due to surface coating of TiO2 nanocrystalsby Eu2O3, we obtained 27% anatase phase at 1000 °C heated sample, which is new observation in this study.The lattice volume decreases with decreasing the particle size for anatase particle and a nonlinear sizedependency of lattice parameters is obtained at size <10 nm. However, the lattice volume increases withdecreasing the particle size in rutile phase. Again, we obtained that the lattice strain of doped (tensile) sampleis different from coated (compressive) sample. The mechanism related to morphology control for doped andcoated (TiO2:Eu) nanoparticles is proposed and discussed. The growth mechanism is different for coated anddoped (orientated attachment) nanocrystals. It is also found that photoluminescence properties of Eu3+ ionsare sensitive to the crystal structure which is again controlled by the surface coating and temperature ofheating. The emission intensity of the peak at 614 nm (5D0 → 7F2) for Eu3+ ions for coated TiO2 nanocrystalsis greater than doped sample.
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