Microstructural and photoluminescence properties of CTAB/PVP capped ZnO nanocrystals

• Published in: Optik (Stuttgart) Vol. 130; pp. 955 - 962
• Main Authors: Kalita, Amarjyoti, Kalita, M.P.C.
• Format: Journal Article
• Language: English
• Published: Elsevier GmbH 01.02.2017
• Subjects: Luminescence; Nanocrystalline materials; Optical materials and properties; Rietveld refinement; Semiconductors; Structural; X-ray techniques; Rietveld refinement; Semiconductors; Nanocrystalline materials; Luminescence; Structural; Optical materials and properties; X-ray techniques
• ISSN: 0030-4026; 1618-1336
• DOI: 10.1016/j.ijleo.2016.11.034

ZnO nanocrystals of crystallite size 30nm are synthesized using cetyl trimethyl ammonium bromide (CTAB)/polyvinylpyrrolidone (PVP) as capping agent. Capping by CTAB/PVP is confirmed using Fourier transform infrared spectroscopic measurements. Rietveld refinement and Williamson-Hall methods of X-ray diffraction pattern analysis are applied to gather microstructural information such as crystal phase, lattice parameters, lattice volume, crystallite size, lattice strain, stress and energy density of the nanocrystals. Band gaps obtained from UV–vis absorbance measurements are found to be the same (3.13eV) for both CTAB and PVP capped nanocrystals. For the PVP capped ZnO nanocrystals, broad photoluminescence centered at 538nm (green) is observed with less intensity as compared to the signature UV emission of ZnO. On the contrary, CTAB capped nanocrystals exhibit broad emission in the visible region centered at 556nm (yellowish green) which has intensity nearly equal to the UV emission. The observed visible emissions in the CTAB and PVP capped nanocrystals are attributed to oxygen antisite defect and singly ionized oxygen vacancy, respectively. Thus, CTAB and PVP can be used to obtain ZnO nanocrystals of same crystallite size and band gap exhibiting different defect states and luminescence properties.