Papers by Keyword: Field Emission Scanning Electron Microscopy (FESEM)

Abstract: A series of single carbon source and metal oxide assisted carbon source were prepared by mechanochemical process followed by carbothermal reduction which obtained via the reaction between activated carbon (AC) from rubber wood sawdust (Havea brasiliensis) and CuO precussor. Microstructure of the single AC and CuO assisted AC (CuO-AC) has been studied using Field Emission Scanning Electron Microscopy (FESEM). The products were further characterized using X-ray diffraction (XRD) and thermal analysis (TG and DTA). A significant difference of the microstructure between AC and CuO-AC samples were observed in FESEM micrograph. The micrograph of single AC in indicates porous structure with numerous pores present due to dehydration of volatile matters. Milling process and reduction of CuO by AC has contributed to the increasing formation of porous structure with nanopore size ranging from 100-200 nm. TG and DTA results revealed that single AC and CuO-AC have a significant difference in thermal decomposition and stability. Doping of CuO to AC has affected the exothermic and endothermic reaction of the samples. These were further being clarified by X-ray diffraction where phase analysis is studied. It was found that the addition of CuO to AC brought a significant increase in the degree of crystallinity which is accompanied by mechanochemical process followed by carbothermal reduction to produce Cu. Incomplete reduction also cause the formation of Cu₂O. Production of CuO-AC were successfully characterized and revealed the potential enhancement for waste treatment.

Abstract: Mechanochemical process was conducted to synthesis a series of metal oxide doped biomass carbon source followed by carbothermal reduction which obtained via the reaction between activated carbon (AC) and CuO precursor. Microstructure of single AC and CuO-doped activated carbon was conducted using Field Emission Scanning Electron Microscopy (FESEM). Thermal behavior was studied using thermogravimetric analyser and Differential Scanning Calorimetry (TGA and DSC) and crystallinity phase was analysed using X-ray diffraction (XRD). The results indicated that mechanochemical process and carbothermal reduction to synthesis CuO-doped AC have a significant effect in term of surface morphology, thermal decomposition and crystallinity. A significant difference of the surface morphology between AC and CuO-AC samples were observed. TGA/DSC analysis revealed that doping of CuO to AC has affected the exothermic and endothermic reaction of the samples. Doping of CuO to AC also brought a significant increase in the degree of crystallinity due to the carbothermal reduction of CuO into Cu. Production of CuO-doped AC was successfully characterized and revealed the potential enhancement for waste treatment.

Abstract: This study was done to investigate the microstructures of nanocrystalline cellulose (NCC) after hydrolysis with mineral acid concentrated. The optimum NCC was achieved through acid hydrolysis and the NCC was used as a reinforcement in nitrile butadiene rubber composites. The Field Emission Scanning Microscopy (FESEM) was used to study the structures and surfaces of the NCC and composites produced. The NCC that was synthesis from microcrystalline cellulose (MCC) found to be more individual and agglomerated due to hydrogen bonding between the NCCs, the more individual NCC produced would create more surface area to be bonded with NBR as a reinforcement. More surface area of NCC was good to create physical bonding with NBR and increase mechanical performance of composites. The NCCs in NBR composite found to form agglomeration caused by different properties that exhibited by both materials. This can restrict and reduce the performance of composite produced. A combination of these materials can be used as a reinforcement but need more attention on the modification to make these materials more compatible. Further research can be done to find the best way to prevent agglomeration between these both materials.

Abstract: Composite cathode La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ-SDC carbonates (LSCF-SDCC) for applications of low temperature solid oxide fuel cell (LTSOFC) were developed. LSCF-SDCC were mixed using high energy ball milling technique via dry and wet milling method followed by calcinations at 700, 750 and 800 °C. The findings reveal that different calcinations temperature and milling techniques gives effects to the composite cathodes powder. Clear peak intensity demonstrate from wet milling technique as confirm via XRD analysis indicates that crystalline structure has been improved. FESEM investigation demonstrate the presence of large particles in the resultant powder resulting from the increased calcination temperature. LSCF-SDCC composite cathodes powder produced via wet milling technique have good fine fraction and demonstrates good crystallite structure to be served as cathode of LTSOFC compared to dry milling technique.

Abstract: 1¹/₄Cr¹/₂Mo³/₄Si (T11) and 2¹/₄Cr1Mo (T22) grade steels are extensively used in critical parts of sub-critical thermal power plants like superheater, reheater tubes or headers. The tubes are designed to last for a very long time in service. These tubes are exposed to hot flue gas on the outer side and consequently, the inner side heats the steam passing through the tube. The outlet temperature of the steam ranges from 500-550°C. Therefore, not only the temperature on the outer side is much higher than the steam outlet but also the environment which the tube faces is extremely corrosive thereby leading to hot corrosion/ fireside corrosion. Some parts of the tubes are also exposed to fly ash coming from the combustion of coal leading to the formation of deposits on the tubes. In the present work, the tubes are cut and taken out during overhaul shutdowns and they are characterized by X-Ray Diffraction (XRD) for the likely phases that are formed on the surface of the fireside corroded layer. The deposits/scales are also qualitatively characterized. The cross-sections of the tubes are used for characterization of fireside corroded product layers using Optical Microscopy and Field Emission Scanning Electron Microscopy (FESEM) coupled with Energy Dispersive X-Ray Spectroscopy (EDS). This work will be extended further to develop rate laws and rate mechanisms of the corrosion product layers formed on the service exposed tubes.

Abstract: ZnO nanostructures with different morphology were successfully prepared via a hexamethylendiamine-assisted hydrothermal synthesis route by only adjusting reaction temperature. The prepared ZnO samples were characterized by powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and high resolution TEM (HRTEM). Results indicated that uniform flake-like ZnO nanoparticles with a similar thickness of about 70 nm and flower-like ZnO nanostructures assembled by prism-like nanorods were prepared at 120 °C and 180 °C, respectively. Possible mechanisms for the formation of ZnO with different morphologies were discussed. The photocatalytic properties of the as-prepared flake-like ZnO nanoparticles and flower-like ZnO nanostructures were studied.

Abstract: The paper presents the fabrication of Si₃N₄ nanowires prepared on Si substrate by plasma-enhanced chemical vapor deposition (PECVD) technology. The nanowires were formed using silane (SiH₄) and nitrogen (N₂) as reactive gases under the action of Fe catalysts. They are characteristics of superlong straight and flexural types observed by field emission scanning electron microscopy (FESEM). The former with a length of 3.96 mm has smooth surface and uniform diameter resulting from an orientation growth process, while the latter is 5.20 mm formed by two nanowires twisted together with a squeezing growth way. A growth model has been developed for the formation of the nanowires, and the growth mechanism of the nanowires has been discussed. The straight and flexural Si₃N₄ nanowires can be used as nano-scaled bridge, spring, and cantilever in the fabrication of nano-machine systems.

Abstract: The experiment discusses the issue of high-energy implant to the resist thickness and how the resist etched away during implantation process. The resist that is use as a mask or material to block the dopant ion such as Phosphorous, Boron or Arsenic introduces into silicon substrate. It is a common practice by all semiconductor industrial players to use photoresist as their protection on desired area in which purposely set as non-implanted area. The research benefits the engineer on determine the sufficient photoresist thickness for specific implant energy.

Abstract: We report the growth of well-aligned RuO2/R-TiO2 heteronanostructures on sapphire (100) substrates by reactive magnetron sputtering using Ti and Ru metal targets under different conditions. The surface morphology and structural properties of the as-deposited heteronanostructures were characterized using field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and selected-area electron diffractometry (SAED). The FESEM micrographs and XRD patterns indicated the growth of vertically aligned RuO2(001) nanotubes and twinned V-shaped RuO2(101) nanowedges (NWs) on top of R-TiO2 nanorods under different sputtering pressures. TEM and SAED characterizations of the V-shaped RuO2 NWs showed that the NWs are crystalline RuO2 with twin planes of (101) and twin direction of [ 01] at the V-junction.

Abstract: Silver nanoparticle thin films were deposited on glass substrates by electrostatics spray deposition. Electrostatic spray condition was optimized by varying distance between nozzle and substrate between 20 mm and 60 mm, deposition time was fixed at 5 minute. The surface morphology and optical properties of films were carried out by using Atomic Force Microscope (AFM), Field Emission Scanning Electron Microscopy (FE-SEM) and UV-Vis Spectrophotometer. The results is indicate that the surface morphology of silver nanoparticle thin film show the grain size of film near around 100 nm at distance between nozzle and substrate of 60 mm and the RMS roughness decreases from 9.59 nm to 2.35 nm when distance between nozzle and substrate was increased from 20 mm to 60 mm. The optical absorption spectra showed the main absorption peak at 436 nm. When the distance between the nozzle and the substrate raise, decrease in absorption has been observed.