Papers by Author: S.A. Mohamad

Abstract: This paper discusses the dependence of microstructure and mechanical properties of sintered biphasic calcium phosphate (BCP) on sintering temperature and compacting pressure of BCP dense bodies. BCP nanopowders were prepared via hydrothermal method using eggshell as the calcium source, followed by compaction into circular disc shape at various pressure and sintered pressureless in air at various sintering temperatures. X-ray diffraction analysis of nanopowders revealed the existences of hydroxyapatite (HA) as the main phase, with β-tricalcium phosphate (β-TCP) and calcium pyrophosphate (CPP) as the second phases. Morphological evaluation by scanning electron microscopy showed BCP exhibited uniform microstructure at low temperature and coalescence of pores and exaggerated grain growth at increasing temperature. Mechanical strength tests shown by compression strength and Vickers’ hardness test revealed an increase of strength with increasing temperature of up to 1100°C, after which it dropped. Mechanical strength also proved to be better with higher compacting pressure.

Abstract: Crystalline thin of zinc selenide have been electrochemically deposited on conducting substrates of indium tin oxide, ITO glass. Initial investigation with voltammetry was done and shows that the zinc selenide films were stable towards oxidation. The best deposition potential obtained was at -0.95 V vs. Ag /AgCl while at lower deposition potentials, the films do not form well. Energy Dispersive Analysis and X-Ray spectrum indicate that the films deposited at 65oC and -0.95 V vs. Ag/AgCl have nearly stoichiometric Zn: Se ratio.

Abstract: Electrodeposition of ZnTe thin films by controlled potential method from aqueous solutions on ITO were done to investigate characteristics suitable as a window material in solar cells technology. The influence deposition of potential towards the Zn:Te ratio and the crystallinity are discussed. The electrodeposited films were investigated by using X-Ray Diffraction and Energy Dispersive Analysis of X-Ray. The Te content decreases at higher deposition potentials.

Abstract: The properties of ZnSe/PEO junction photoelectrochemical cells have been studied under dark and illuminated conditions. ZnSe was electrodeposited onto an indium tin oxide (ITO) glass and the polymer film of PEO-chitosan: NH4I (+I2) was placed over it followed by another ITO glass. The polymer film was prepared by the solution cast technique. The open circuit voltage (Voc) of the fabricated cells was between 300 mV to 400 mV. In the dark the device operates as a diode while under illumination it operates as a photoelectrochemical cell.