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Start date: 2020Subject: search.filters.subject.Annealing temperature

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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
    ;
    Promros, Nathaporn
    ;
    Chaleawpong, Rawiwan
    ;
    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.