Norlida Kamarulzaman

Sol-Gel Synthesis of Highly Stable Nano Sized MgO from Magnesium Oxalate Dihydrate

A sol-gel method was used to synthesize a highly stable form of MgO from magnesium oxalate dihydrate. The sol-gel products were characterized using simultaneous thermogravimetric analysis (STA), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and UV-Visible light spectroscopy (UV-Vis). From the XRD analysis, all the MgO samples showed a single face-centered cubic phase. FESEM micrographs showed a crystallite size ranging from 10 nm to 59 nm. The size of the MgO crystallites increased with increasing temperatures. The crystallite size of the MgO is still relatively small, that is, below 100 nm even when the precursor was calcined at a higher temperature of 950 °C and a longer time of 36 h. Such results indicated that the growth of the crystallites is slow for this route of synthesis. The morphologies of the MgO samples are varied from the all spherical of the lower temperature to the more cubic shape with less agglomeration of the higher calcined samples. The band gap energy of the MgO samples also increased with temperature.

Synthesis and Battery Studies of Sodium Cobalt Oxides, NaCoO2 Cathodes

Sodium based batteries presented a new and promising battery system. This work attempted to develop NaCoO2 material using a new sol-gel method. The characterization of this sodium based material was done by using Thermogravimetric Analysis (TGA), X-Ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM). Cyclic voltammetry showed that the material exhibit reversible oxidation and reduction peaks which meant that a sodium based battery was possible for this material. Electrochemical charge-discharge profile was performed to study the voltage plateaus exhibited by the material. It showed discharge plateaus of between 3.2 to 2.3 V and another plateau at 0.6 V.

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

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

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.

Effects of the absorption behaviour of ZnO nanoparticles on cytotoxicity measurements

ZnO absorbs certain wavelengths of light and this behavior is more pronounced for nanoparticles of ZnO. As many toxicity measurements rely on measuring light transmission in cell lines, it is essential to determine how far this light absorption influences experimental toxicity measurements. The main objective was to study the ZnO absorption and how this influenced the cytotoxicity measurements. The cytotoxicity of differently sized ZnO nanoparticles in normal and cancer cell lines derived from lung tissue (Hs888Lu), neuron-phenotypic cells (SH-SY5Y), neuroblastoma (SH-SY5Y), human histiocytic lymphoma (U937), and lung cancer (A549) was investigated. Our results demonstrate that the presence of ZnO affected the cytotoxicity measurements due to the absorption characteristic of ZnO nanoparticles. The data revealed that the ZnO nanoparticles with an average particle size of around 85.7nm and 190nm showed cytotoxicity towards U937, SH-SY5Y, differentiated SH-SY5Y, and Hs888Lu cell lines. No effect on the A549 cells was observed. It was also found that the cytotoxicity of ZnO was particle size, concentration, and time dependent. These studies are the first to quantify the influence of ZnO nanoparticles on cytotoxicity assays. Corrections for absorption effects were carried out which gave an accurate estimation of the concentrations that produce the cytotoxic effects.

Solid Solutions of LiCo1-xNixO2(x=0,0.1,...,0.9) Obtained via a Combustion Synthesis Route and Their Electrochemical Characteristics.

Pure, single-phase and layered materials with good cation ordering are not easy to synthesize. In this work, solid solutions of (x = 0, 0.1, …, 0.9) are synthesized using a self-propagating combustion route and characterized. All the materials are observed to be phase pure giving materials of hexagonal crystal system with R-3m space group. The RIR and R factor values of stoichiometries of (x = 0.1, 0.2, 0.3, 0.4, and 0.5) show good cation ordering. Their electrochemical properties are investigated by a series of charge-discharge cycling in the voltage range of 3.0 to 4.3 V. It is found that some of the stoichiometries exhibit specific capacities comparable or better than those of LiCoO2, but the voltage plateau is slightly more slopping than that for the LiCoO2 reference material.

Evaluation of the electrochemical capacity of spinel Li1.0348Mn1.9152Fe0.0494O4 compound from combined X-ray diffraction and particle size distribution measurements

A cathode material of the form Li1.0348Mn1.9152Fe0.0494O4 was prepared by a sol-gel method for lithium ion batteries. The synthesized material was found to have a pure cubic spinel structure of Fd3¯m

Surface Modification of Polyvinylidenefluoride-Trifluoroethylene Film Using Argon Gas Plasma

Fd\overline{3}m