Papers by Author: Abdul Hadi

Abstract: Nanocrystalline cerium dioxide (CeO2) has been successfully synthesized by mechanochemical technique at 12, 24, 36, 48 and 60 hours milling times. The starting materials, hydrated cerium carbonate and sodium hydroxide, were mixed in a weight ratio of 4:1 and were milled in a planetary ball mill with ball to powder ratio of 10:1. The high energy impact forces provided by the milling media caused collision of starting materials and allowed the chemical reaction to occur thus produced nanocrystalline cerium dioxide. The products were characterized using a battery of characterization methods, including thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and gas adsorption-desorption measurement. The nanocrystalline CeO2 with 6.7 nm of crystallite size and specific surface area of 66.66 m2/g was obtained when the sample was milled for 60 hrs and they annealed in air at 350 oC. The result showed that the crystallinity of nanocrystalline CeO2 decreased with increasing milling time.

Abstract: Cerium dioxide (CeO2) nanoparticles were synthesized by a novel mechanochemical process. The precursors of Ce2(CO3)3.xH2O and NaOH were mixed at a weight ratio of 4 to 1. The mixtures were milled using a planetary ball mill with ball to powder ratio of 10:1. The products were then characterized using a battery of characterization methods, including X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and gas adsorption-desorption measurement. The as-prepared particles were largely amorphous with an average specific surface area of about 119.94 m2/g. Nanocrystalline CeO2 with crystallite size of 4.5 nm was obtained when the sample was annealed in air at 350 oC. The heat treatment results showed that the crystallinity of nanocrystalline CeO2 increased with increasing annealing temperature.

Abstract: Nanocrystalline CeO2 has been synthesized at room temperature using water-in-oil (w/o) microemulsion technique. The structure and properties of the nanocrystalline CeO2 were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and gas adsorption desorption measurement. XRD results showed the synthesized CeO2 has a face centered cubic structure with crystallite size of about 5.2 nm. TEM observation also indicated the presence of nanometer sized particles of CeO2. Coarser particles were also observed due to agglomeration. Gas adsorption desorption isotherms showed the behavior of fine particles with mesoporous structure.