Effects of Cr-Doping on Structural and Optical Properties of ZnO Nanoparticles

The synthesis method, structural and optical properties of sol-gel derived Zn1-xCrxO (0 <= x <= 0.06) nanoparticles has been reported. Rietveld refinement of X-ray diffraction pattern shows that all the samples are in single phase having wurtzite structure. It also confirms that Cr-ions are well incorporated into host lattice without changing the wurtzite structure of ZnO host lattice. X-ray diffraction and transmission electron microscopy observations showed the nanocrystalline nature of the samples. UV-Vis measurements show that the band gap is blue shifted in lower Cr-concentration and red shifted in higher Cr-concentration. This may be attributed due to the Burstein-Moss effect that prevails throughout this range of doping and sp-d exchange interaction which plays a significant role for higher Cr-concentration.