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Green synthesis and optimized annealing tempserature effects on zinc oxide nanoparticles using mango peel extract
(2026-01-01)
Wirunchit, Supamas
;
Sakulpeeb, Natchayaporn
;
Meedech, Woradech
;
Chutipaijit, Sutee
;
Koetniyom, Wantana
This study presents the green synthesis of zinc oxide nanoparticles (ZnO-NPs) using mango peel extract (MgE) as a natural reducing and stabilizing agent. Phytochemical extraction was performed with deionized water, ethanol, and methanol for 1 h to 5 h, with deionized water at 4 h yielding the highest flavonoid content. Using zinc nitrate as a precursor, 25 mL of MgE successfully facilitated the synthesis of ZnO-NPs (ZnO-25MgE). It was found that annealing temperature at 400°C for 6 h produced pure ZnO. The obtained nanoparticles were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and field emission scanning electron microscopy (FE-SEM). XRD confirmed the crystalline structure with an average size of 6.67 nm, while FT-IR and FE-SEM analyses revealed Zn–O vibrations, residual organics, and nanoscale morphology. Thermogravimetric analysis (TGA) indicated the appropriate annealing temperature for the removal of organics. For comparison, chemically synthesized ZnO was also characterized, and its antibacterial activity was assessed via disc diffusion against Escherichia coli and Staphylococcus aureus. The results demonstrated notable inhibition, highlighting the potential of biosynthesized ZnO-NPs for antimicrobial applications.
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Impact of annealing temperature and carbon doping on the wetting and surface morphology of semiconducting iron disilicide formed via radio frequency magnetron sputtering
(2020-09-01)
Charoenyuenyao, Peerasil
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Promros, Nathaporn
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Chaleawpong, Rawiwan
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Borwornpornmetee, Nattakorn
;
Sittisart, Pattarapol
Iron disilicide (FeSi<inf>2</inf>) films were formed onto Si(111) substrates via radio-frequency magnetron sputtering at room temperature (RT) and 560 °C. The effects of annealing temperature and carbon (C) doping concentration on the physical properties of FeSi<inf>2</inf> films were investigated. For annealing conditions, the crystallinity of the unannealed FeSi<inf>2</inf> films was enhanced after annealing. The surface of unannealed FeSi<inf>2</inf> films consisted of many small crystallites, which were clustered after annealing at 500 °C. The root mean square roughness (R<inf>rms</inf>) of the unannealed FeSi<inf>2</inf> films increased from 0.94 nm to 5.32 nm after air-annealing at 500 °C. The surface of the unannealed FeSi<inf>2</inf> films exhibited an average contact angle (θ<inf>CA</inf>) of 102.35°, which decreased to 41.70° after annealing at 500 °C. For C-doping conditions, the X-ray diffraction patterns for the undoped and C-doped FeSi<inf>2</inf> revealed β(202/220) and β(404/440) peaks. The undoped FeSi<inf>2</inf> film surfaces presented many small grains with grain boundaries, where the C-doped FeSi<inf>2</inf> films displayed a finer surface. R<inf>rms</inf> of the undoped FeSi<inf>2</inf> film surface was 15.71 nm, which decreased to 10.59 nm for 3.0 at.% C-doped FeSi<inf>2</inf> films. The average θ<inf>CA</inf> of the undoped FeSi<inf>2</inf> films was 108.35°, and this reduced slightly to 103.65° for 3.0 at.% C-doped films. Based on the obtained results, it was shown that the as-formed FeSi<inf>2</inf> and FeSi<inf>2</inf> films after annealing at 100 and 300 °C formed at T<inf>sub</inf> of RT, together with the undoped and C-doped FeSi<inf>2</inf> films formed at T<inf>sub</inf> of 560 °C, could potentially be employed for hydrophobic coating applications.
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The influence of annealing temperature on structural properties of zinc oxide nanoparticles synthesized by precipitation method
(2017-01-01)
Chaithanatkun, Natpasit
;
Onlaor, Korakot
;
Tunhoo, Benchapol
In the present work, the precipitation method was used to prepare zinc oxide nanoparticles in the presence of zinc nitrate and potassium hydroxide as zinc precursor and hydroxide precursor, respectively. The influence of annealing temperature on the structural, morphological, and vibrational properties of zinc oxide nanoparticles was studied by X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), Fourier transform Raman spectroscopy (FT-Raman), and Fourier transform infrared spectroscopy (FT-IR) techniques. The effects of annealing temperature on the crystallite size of zinc oxide nanoparticles were investigated. The XRD results represented that the zinc oxide nanoparticles exhibited high crystallinity of hexagonal wurtzite crystal structure. The average crystallite size of nanoparticles increased from 25 nm to 31 nm with an increase in annealing temperature from 600°C to 800°C. The SEM images showed that the prepared zinc oxide nanoparticles in this present work were spherical in shape and had the larger size with increasing annealing temperature. FT-Raman and FT-IR spectra confirmed that the quality of Zn-O vibrational mode was stronger at higher annealing temperature.
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Transparent light-guided plates based on TiO2/Rhodamine6G composite thin films
(2016-11-25)
Mekprasart, Wanichaya
;
Pecharapa, Wisanu
Transparent light-guided plates for solar cell application from nano-titanium dioxide (TiO<inf>2</inf>), rhodamine 6G (R6G) and poly methyl methacrylate (PMMA) composite films were prepared by spin coating technique on glass substrates. Effects of the annealing temperatures and times on the formation of the TiO<inf>2</inf> crystalline film that acted as an initial model for the light-scattered layer in solar concentrators were investigated. Physical and morphological properties of the TiO<inf>2</inf> film were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and atomic force microscope (AFM). After the annealing process, TiO<inf>2</inf> films obviously formed in the anatase phase with the enlarged crystallite size and the high rough surface by the increase of the annealing temperature and the treating time. Meanwhile, the optical properties of the TiO<inf>2</inf> thin films were analyzed via a UV–Vis spectrophotometer. The transparency of the film was significantly affected by the annealing temperature and the aging time. Moreover, the light scattering performance of the TiO<inf>2</inf> layer cooperated with Rhodamine6G in the PMMA matrix as the preliminary model of light-guide plate was investigated by fluorescence spectra. Strong light emission from the light-guide plate could be significantly enhanced by the existence of the TiO<inf>2</inf> crystalline layer acting as the scattering film. Optimized performance of the planar light-guide plate incorporated with Rhodamine6G dye and the light-scattered TiO<inf>2</inf> layer was obtained from the film annealed at 500 °C for 5 h.

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