Annealing Effects on the Structural and Optical Properties of ZnO Nanostructures

Abstract

ZnO nanostructures were synthesized by a proteic sol-gel method, using zinc nitrate hexahydrate and gelatin as precursors. Size and shape evolution of ZnO nanostructures were achieved by annealing temperature in the range 250-1000 ºC. The crystalline structure, morphology and optical properties of the ZnO nanoparticles were characterized by X-Ray Diffraction (XRD), Raman Spectroscopy (RS), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and room temperature Photoluminescence (PL). The result of structural characterization shows the formation of platelets and nanorods in the micro-scale and ZnO nanostructures with high quality hexagonal wurtzite crystal. Sharp peaks in RS after annealing temperature, related to wurtzite structure, were observed corroborating with XRD and TEM measurements. Room temperature PL spectra showed two contribution bands which peaked at ~380 nm, originating from the recombination of free excitons, and ~520 nm corresponding to the impurities and structural defects, like oxygen vacancies and zinc interstitial. The effects of annealing temperature in the structural and optical properties are detailed and the results compared among the experimental techniques. The high quality of the samples obtained by an alternative organic precursor method opens a low-cost route to technological applications of zinc oxide.

Dehydration of 1,5‐Pentanediol over ZrO2‐ZnO Mixed Oxides

“…The ZrO 2 sample showed peaks at 149, 273, 319, 465, and 647 cm −1 , and peak positions are matched to the reported values for tetragonal‐ZrO 2 . For 50Zr50Zn, additional bands appear at 100, 441, and 604 cm −1 can be attributed to hexagonal ZnO . The intensity of these bands was raised with increasing Zn content indicating 30Zr70Zn and ZnO samples have a higher proportion of ZnO compared to 50Zr50Zn.…”

Synthesis of ZnO Nanoparticles by the Sol-Gel Protein Route: A Viable and Efficient Method for Photocatalytic Degradation of Methylene Blue and Ibuprofen

“…The sol-gel protein synthesis was similar to that used by Etcheverry et al, 15 performed with 1 g of zinc nitrate (Zn(NO 3 ) 2 .6H 2 O, Sigma-Aldrich, Manaus, Brazil) as an organometallic compound, added to 2 g of commercial gelatin for the gelatinization. The ratio of the metal precursor and gelatin mass was 1:2, homogenized in 200 mL of aqueous KOH (Sigma-Aldrich, Manaus, Brazil) solution for 50 min.…”

“…Analyzing XRD measurements it was also possible to estimate the average crystallite size of ZnO by the Scherrer equation, 15 obtaining the value of 21.1 nm for the heat treatment at temperature of 1000 °C.…”

“…In the sol-gel protein route these steps occur when some of the constituents of the gelatin bind to the metal. 15 The sol-gel protein route, in addition to being environmentally friendly and low cost, makes use of progressively increasing supports, viscosity and elasticity, creating a 3D structure to support metal particles and the unwanted components of these supports are easily eliminated with increasing temperature. 15 In this study it is possible to see the efficiency of zinc oxide, prepared by sol-gel protein route, in the degradation of a solution of dye and of a drug when synthesized via sol-gel protein.…”

Synthesis and characterization of single phase ZnO nanostructures via solvothermal method: influence of alkaline source

“…All these methods produce similar nanocrystalline structures based on different conditions. These conditions may arise from the precursor and alkaline sources used, temperature variation, reaction time for nucleation of the nanoparticles as well as the calcination temperatures [28][29][30]. It should be noted that some of the methods employed in fabricating these nano-sized particles require complex processes and sophisticated equipment.…”