Mohd Mahadi Halim

Morphological and structural characterization of single-crystal ZnO nanorod arrays on flexible and non-flexible substrates

Summary We report a facile synthesis of zinc oxide (ZnO) nanorod arrays using an optimized, chemical bath deposition method on glass, PET and Si substrates. The morphological and structural properties of the ZnO nanorod arrays were investigated using various techniques such as field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) measurements, which revealed the formation of dense ZnO nanorods with a single crystal, hexagonal wurtzite structure. The aspect ratio of the single-crystal ZnO nanorods and the growth rate along the (002) direction was found to be sensitive to the substrate type. The lattice constants and the crystallite size of the fabricated ZnO nanorods were calculated based on the XRD data. The obtained results revealed that the increase in the crystallite size is strongly associated with the growth conditions with a minor dependence on the type of substrate. The Raman spectroscopy measurements confirmed the existence of a compressive stress in the fabricated ZnO nanorods. The obtained results illustrated that the growth of high quality, single-crystal ZnO nanorods can be realized by adjusting the synthesis conditions.

Theoretical studies on mechanical and electronic properties of s-triazine sheet

Abstract Mechanical and electronic properties of s-triazine sheet are studied using first-principles calculations based on density functional theory. The in-plane stiffness and bulk modulus for s-triazine sheet are found to be less than that of heptazine. The reduction can be related to the nature of the covalent bonds connecting the adjacent sheets and the number of atoms per unit cell. The Poisson’s ratio of s-triazine sheet is half the value to that of graphene. Additionally, the calculated values of the two critical strains (elastic and yielding points) of s-triazine sheet are in the same order of magnitude to that for heptazine which was calculated using MD simulations in the literature. It is also demonstrated that s-triazine sheet can withstand larger tension in the plastic region. These results established a stable mechanical property for s-triazine sheet. We found a linear relationship of bandgap as a function of bi-axial tensile strain within the harmonic elastic region. The reduced steric repulsion of the lone pairs (px-, py-) causes the pz-like orbital to shift to high energy, and consequently an increase in the bandgap. We find no electronic properties modulation of the s-triazine sheet under electric field up to a peak value of 10 V/nm. Such noble properties may be useful in future nanomaterial applications.

Effects of atoms and molecules adsorption on electronic and magnetic properties of s-triazine with embedded Fe atom: DFT investigations

Abstract We employ first-principles calculations to study the mechanical, geometrical, electronic and magnetic properties of Fe atom embedded s-triazine () system under the influence of external environment. Our results show that the binding energy of can be modulated by an applied tensile deformation and perpendicular electric field. The non-magnetic semiconducting property of pure s-triazine sheet () is found to change upon embedding of Fe atom in the porous site of the sheet. It is revealed that the system exhibit half-metallic electronic character with a magnetic moment in the order similar to that of an isolated Fe atom. Furthermore, electronic and magnetic properties of the systems are preserved up to a maximum value of 10 V/nm in electric field strength and 6% tensile strain. Interestingly, we find that the half-metallic electronic character can be tuned into semiconductor via adsorption of atoms and molecules into the system. The magnetic moment of with adsorbed atoms/molecules is also modified. Our findings may serve as a guide for future applications of structures in spintronics devices.