Nor Fadilah Chayed

Bio: Nor Fadilah Chayed is an academic researcher from Universiti Teknologi MARA. The author has contributed to research in topics: Band gap & Magnesium. The author has an hindex of 6, co-authored 21 publications receiving 165 citations.

Elucidation of the highest valence band and lowest conduction band shifts using XPS for ZnO and Zn0.99Cu0.01O band gap changes

Abstract: ZnO and Zn0.99Cu0.01O nanostructures were prepared by a simple sol–gel method. The band gaps of the materials were systematically studied based on the dependence of the dimensions of the nanostructures as well as the presence of a dopant material, Cu. ZnO and Zn0.99Cu0.01O nanostructures were found to exhibit band gap widening whilst substitution of Cu in the lattice of ZnO caused its band gap to narrow with respect to the pure ZnO materials. In order to understand the phenomenon of band gap change, structural, spectroscopic, particle size and morphological studies were done. The band gap change occurring when the materials were in the nanostructured phase was proven to be mainly due to the downward shift of the valence band. Interestingly, when the band gaps of the pure ZnO and Cu doped ZnO were compared, the band gap changes were due to different shifts of the valence bands.

Band Gap Energies of Magnesium Oxide Nanomaterials Synthesized by the Sol-Gel Method

Abstract: In this work, the band gap energies of magnesium oxide (MgO) were investigated to see if calcination time affects the band gap energies of the MgO. MgO nanomaterials have been prepared by a sol-gel method. MgO precursors produced were calcined at a temperature of 600 °C for 24 hours and 48 hours. The structural characterization of samples is achieved using X-Ray Diffraction (XRD) and the morphology as well as particle size of MgO were examined by Field Emission Scanning Electron Microscopy (FESEM). UV-Vis NIR spectroscopy was used to determine the band gap energies of the materials. From the results, the band gap energy of the MgO with a longer heating time exhibited a higher value.

Optical Band Gap Energies of Magnesium Oxide (MgO) Thin Film and Spherical Nanostructures

Abstract: Magnesium oxide (MgO) is one of the metal oxides which has unique properties and has great potential applications in industry. In this work, MgO was synthesized by using a sol‐gel and solid state methods. The precursor of MgO was annealed at the temperature of 600 °C for 1 hour and 800 °C for 24 hours for sol‐gel method. For solid state method, magnesium acetate was annealed at the temperature of 800 °C for 24 hours. These samples were characterized by using X‐Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). TEM micrographs show the morphology of the samples of the sol‐gel method are thin film nanostructures whereas sample of the solid state method is spherical shape. The band gap energies of the samples were measured using UV‐Vis NIR Spectrophotometer. The band gap values of the samples were calculated and it was found that there is a difference of band gap energies between samples employing different synthesis route.

Handbook on physical properties of semiconductors

Abstract: Magnesium Oxide (MgO).- Zincblende Magnesium Sulphide (?-MgS).- Zincblende Magnesium Selenide (?-MgSe).- Zincblende Magnesium Telluride (?-MgTe).- Zinc Oxide (ZnO).- Wurtzite Zinc Sulphide (?-ZnS).- Cubic Zinc Sulphide (?-ZnS).- Zinc Selenide (ZnSe).- Zinc Telluride (ZnTe).- Cubic Cadmium Sulphide (c-CdS).- Wurtzite Cadmium Sulphide (w-CdS).- Cubic Cadmium Selenide (c-CdSe).- Wurtzite Cadmium Selenide (w-CdSe).- Cadmium Telluride (CdTe).- Cubic Mercury Sulphide (?-HgS).- Mercury Selenide (HgSe).- Mercury Telluride (HgTe).

Fabrication of MgO nanostructures and its efficient photocatalytic, antibacterial and anticancer performance.

Abstract: Magnesium oxide (MgO) nanostructures were prepared using microwave-assisted (M 1) and hydrothermal (M 2) methods and characterized by XRD, SEM and FT-IR. It exhibits cubic structure with an average crystallite size of 20 nm (M 1) and 14 nm (M 2) and the lattice strain (W H plot) is 0.0017 (M 1), 0.0037 (M 2). It's spherical and rods like structures are confirmed through SEM and TEM. The vibrational stretching mode of Mg O is 439 (M 1) and 449 cm−1 (M 2). The optical bandgap is estimated as 5.93 eV (M 1) and 5.85 eV (M 2) through UV–Vis spectra. The fluorescence spectrum shows emission peaks at 414 and 437 (M 1) and 367 and 385 nm (M 2). The photodegradation studies of MgO nanostructures were assessed by monitoring the decolorization of methylene blue and Congo red dyes in aqueous solution under sunlight irradiation. The antibacterial activities of M 1 and M 2 are investigated against the gram-negative (Escherichia coli, Shigella flexneri, Salmonella typhi, Proteus mirabilis, Aeromonas hydrophila and Vibrio cholera) and gram-positive (Bacillus subtilis and Rhodococcus rhodochrous) bacteria. The zone of inhibition of 24 (M 1) and 25 mm (M 2) indicates high antibacterial activity towards the gram negative bacterium A. hydrophila. Confocal laser scanning microscopic (CLSM) analysis was utilized for understanding the variation in antibacterial activity between different orientations of MgO nanostructures. The cytotoxicity assay confirmed that the prepared nanostructures are non – toxic to normal healthy RBC's. In-vitro anticancer efficiency (IC50) of MgO nanostructures against human lung cancer cell line (A549) was investigated.