Size variation of Tb-doped Gd₂O₃ nanoparticles studied by X-ray excited luminescence and diffraction

Post-fabrication heat treatment has been found as an effective means for controlling the size distribution of Tb-doped Gd₂O₃ nanoparticles. Variations in the electronic structure and structural order of these doped quantum dots are investigated by using the techniques of X-ray excited luminiscence and diffraction. From room temperature to 1000°C X-ray powder diffraction of this nanoparticle system shows a three-stage transition from featureless data to that of the bulk crystalline structure with increasing particle size. However, substantial changes found in the X-ray excited luminescence are not directly related to the crystalline structure of the nanoparticles. These observations also indicate that bulk-like crystalline phase of the quantum dot material is not a necessary condition for generating the X-ray induced optical effects which are useful for some technological applications.