Correlating the microstructural and photoluminescence properties of ZnO nanoparticles prepared by ball milling

ZnO nanoparticles (NPs) in the size range 7-40 nm have been synthesized by ball milling technique, and microstructural and photoluminescence properties of the NPs are studied by using varieties of techniques. Our results are compared with those of the commercially procured ZnO nanopowders. X-ray diffraction and high resolution transmission electron microscopy studies reveal a compressive strain in the ZnO NPs. Raman studies show broadening and downshift of the ZnO Raman peaks and appearance of a new mode in the milled NPs. UV-visible absorption spectra of milled NPs show enhanced absorption and blue shift of the peak. Room temperature PL spectra show strong emission bands centered at ~380 nm and ~526 nm, and peak profile and intensity these peaks drastically change with increasing milling time. A correlation of the microstructure and photoluminescence properties of NPs is discussed in the light of the quantum size effect and the strain in the NPs.