Ultrafast synthesis of anatase TiO₂ microspheres doped with rare-earth by one-step microwave method

Using a one-step microwave method without any further calcination, various rare-earth (Re) ions doped anatase titania microspheres were synthesized successfully in less than 10 min. TiCl₄ aqueous solution and rare-earth salt solution are used as reactant, and ethanol was used as solvent. Anatase titania microspheres doped with rare-earth ions including Ce(IV), Sm(III), Tm(III) and Tb(III) were obtained without using any template or surfactant. The scanning electron microscopy images show that the particles have well-defined spherical shapes with a relatively narrow size distribution. X-ray diffraction and Raman spectra demonstrate the crystalline phase of the particles to be anatase. The energy-dispersive spectroscopy spectra and elemental mapping identify rare earth elementals distribute in the microspheres uniformly. The valence state of rare-earth in the samples was determined by X-ray photoelectron spectroscopy spectra. The studies provide a super-rapid method to prepare rare earth doped crystalline TiO₂ microspheres, which are useful materials for optical, biological and environmental applications.