Synthesis of zinc oxide nanoparticles elaborated by microemulsion method

• Published in: Journal of alloys and compounds 2010-09, Vol.506 (2), p.944-949
• Main Authors: Yıldırım, Özlem Altıntaş, Durucan, Caner
• Format: Article
• Language: English
• Subjects: Calcination; Chemical synthesis; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Materials synthesis; materials processing; Microemulsions; Morphology; Nanoparticles; Nanopowders; Nanoscale materials and structures: fabrication and characterization; Nanostructure; Nanostructured materials; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Photoluminescence; Physics; Semiconductors; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Surfactants; Zinc; Zinc oxide
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2010.07.125

. [Display omitted] ▶ Spherical and rod-like ZnO nanostructures obtained in reverse microemulsion. ▶ Morphological variations for microemulsion products with surfactant amount. ▶ Formation mechanism for ZnO nanosructres in a reverse emulsion system. ▶ Optical properties of the ZnO nanoparticles. Zinc oxide (ZnO) nanoparticles were synthesized by a reverse microemulsion system formed from sodium bis(2-ethylhexyl)sulfosuccinate (Aerosol OT, or AOT):glycerol:n-heptane. The zinc precursor was zinc acetate dihydrate. The formation of ZnO nanoparticles was achieved by calcination of premature zinc glycerolate microemulsion product in air at 300, 400 and 500 °C. The crystal structure and the morphology of the ZnO nanoparticles were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Thermal analysis was employed to reveal structural and chemical changes during calcination. Both surfactant concentrations – AOT – in the initial microemulsion formulation and the calcination temperature influenced the morphology and size of the ZnO nanoparticles. Low surfactant concentrations (5:5:90, AOT:glycerol:n-heptane, wt.%) resulted in formation of spherical ZnO nanoparticles. The average particle size increased from 15 ± 1 to 24 ± 1 nm with calcination temperature, but spherical morphology remained unchanged after all calcination treatments. The microemulsion system containing higher surfactant amount (30:5:65, AOT:glycerol:n-heptane, wt.%) resulted in rod-like ZnO nanostructures after calcination at 300 and 400 °C, with a diameter of 22 ± 3 and 28 ± 1 nm; and with a length of 66 ± 3 and 72 ± 1 nm, respectively. Further increase in the calcination temperature to 500 °C initiated rod-to-sphere shape transformation for the ZnO nanoparticles produced using this particular microemulsion formulation. For all ZnO microemulsion products, the photoluminescence measurements suggested a high defect concentration which increases with calcination temperature.