Synthesis and characterisation of ZnO nanostructures

Abstract

Istraživanja provedena u ovom radu bila su usmjerena na sintezu i karakterizaciju nanostrukturiranih čestica ZnO. Hidrotermički postupak odabran je kao jednostavan, reproducibilan i ekološki prihvatljiv postupak sinteze čestica ZnO. Kao izvori Zn2+ iona poslužile su Zn(NO3)2·6H2O i ZnCl2 soli, a kao otapalo upotrijebljena je voda uz dodatak 25% otopine NH3. Sinteze su provedene pri temperaturi, T = 160 °C u vremenu od 2, 4 i 24 sata. Nakon izolacije i sušenja u vakuumu, dobiveni bijeli talozi karakterizirani su sljedećim mjernim tehnikama: infracrvenom spektroskopijom (FT-IR), ultraljubičastom/vidljivom spektroskopijom (UV/Vis), pretražnom mikroskopijom s emisijom elektrona s pomoću polja (FE-SEM), energijski razlučujućom rendgenskom spektrometrijom (EDS) te rendgenskom difrakcijom (XRD). Prema FE-SEM rezultatima svi sintetizirani uzorci su u formi štapića heksagonske strukture koji su izgrađeni od osnovnih građevnih jedinica-kristalita sfernog oblika i nanometarskih dimenzija. XRD rezultatima je, za sve sintetizirane uzorke, potvrđena čista heksagonska vurcitna struktura ZnO što je omogućilo određivanje strukturnih parametara kristalne rešetke i volumena jedinične ćelije. Iz UV/Vis spektara određena su optička svojstva čestica ZnO te su izračunate vrijednosti energijskog procijepa, Ebg.Synthesis and characterization of nanostructured ZnO particles were the focus of investigations in this work. The hydrothermal route was chosen as a simple, reproducible and environmental friendly synthesis procedure of ZnO formation. Zn(NO3)2·6H2O and ZnCl2 salts were used as precursors and water as a solvent. 25% NH3 solution was used to adjust pH of solution. The temperature of the synthesis was, T = 160 °C and duration time was 2, 4 and 24 hours. The white vacuum dried precipitates were characterized by following techniques: infrared spectroscopy (FT-IR), ultraviolet/visible spectroscopy (UV/Vis), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectrometry (EDS), and X-ray diffraction (XRD). FE-SEM results have shown that all samples are in the form of hexagonal rods made of the basic building blocks - spherical crystallites of nanometer dimensions. The hexagonal wurtzite structure of ZnO was confirmed for all samples according to the XRD results. The structural parameters and the unit cell volume were calculated. Optical properties of ZnO particles were determined from the UV/Vis spectroscopy measurements and band gap values, Ebg were calculated for all prepared samples