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Tham khảo tài liệu 'solar collectors and panels theory and applications part 9', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 232 Solar Collectors and Panels Theory and Applications band CTB from O-Ti to Eu3 ions. It requires a perfect lattice of TiO2 for charges transfer in order to avoid space charge regions and e-h recombination. So the crystallinity of the TiO2 lattice is to have a pronounced effect on the PL process which should be further investigated. Fig. 6. a XRD patterns and b the corresponding crystallite size D and lattice strain e for the TiO2 Eu nanoparticles on the hydrothermal temperature Based on the Williams and Hall Equation D increases from 7.3 nm to 11.8 nm and e decreases from 38.25 X 10 -3 to 14.82 X 10 -3 for the TiO2 Eu samples when increasing the hydrothermal temperature Fig. 6 . The growth of crystallite and the decrease in lattice strain indicating that the crystallinity of the nanoparticles has been enhanced and that various structural defects such as small displacement of atoms neighboring non-uniform strain and residual stress of the lattice have been gradually eliminated. These defects were reasonably supposed to influence the PL performance. Fig. 7. The TEM images of a Eu3 TiO2-120 b Eu3 TiO2-180 c Eu3 TiO2-240 d HRTEM of Eu3 TiO2-240 Fast-Fourier Transformed diffractogram of Eu3 TiO2-240 inset The morphology of the nanoparticles changes from polyhedron to rod-like with Eu3 doping Fig. 7 which implies that the Eu3 doping plays an important effect on the crystallographic orientation of TiO2 nanocrystal. Eu3 hinders the growth of specific facets of anatase TiO2 based on the oriented attachment mechanism Ghosh Patra 2007 . The similar case was 233 Titanium Dioxide Nanomaterials Basics and Design Synthesis and Applications in Solar Energy Utilization Techniques also observed in Er3 -doped TiC 2. And HRTEM of a representative rod also shows its anatase structure and the corresponding FFT diffractogram demonstrate its single crystal nature Fig. 7d . Fig. 8. a The excitation spectrum of Eu3 TiC2-240 Ầem 612 nm b the emission spectra Ầex 394 nm of the TiC2 Eu3 .
