Mohd Nor Asiah

An investigation on the formation of carbon nanotubes by two-stage chemical vapor deposition

High density of carbon nanotubes (CNTs) has been synthesized from agricultural hydrocarbon: camphor oil using a one-hour synthesis time and a titanium dioxide sol gel catalyst. The pyrolysis temperature is studied in the range of 700-900°C at increments of 50°C. The synthesis process is done using a custom-made two-stage catalytic chemical vapor deposition apparatus. The CNT characteristics are investigated by field emission scanning electron microscopy and micro-Raman spectroscopy. The experimental results showed that structural properties of CNT are highly dependent on pyrolysis temperature changes.

Memristive Behavior of TiO2 Nanostructures Grown at Different Substrate Positioning by Immersion Method

In this paper, the physical characteristics and memristive behavior of TiO2 nanostructures grown at different substrate positioning by wet chemical solution were investigated. TiO2 thin film as a seed layer for TiO2 nanostructures growth was first deposited on ITO-coated substrate by RF magnetron sputtering method. TiO2 nanostructures were then grown by immersing the TiO2 thin film/ITO/glass sample in 10M NaOH solution at 80 °C while studying the effect of the substrate position to the nanostructure growth and thus its memristive behavior. Characterization on the growth morphology of TiO2 nanostructures was observed using scanning electron microscopy (FESEM). The current-voltage (I-V) measurement of the device was investigated for its memristive behavior. Different growth morphology of TiO2 nanostructures was observed at different substrate positioning. It was found that sample immersed with TiO2 layer facing down the vessel result in the formation of TiO2 nanowires and exhibit better memristive behavior.

Effect of TiO2 Seed Layer Thickness to the Growth of TiO2 Nanostructures by Immersion Method for Memristive Device Application

TiO2 nanostructures were successfully grown on TiO2 thin film by solution-based method at low temperature. TiO2 thin film as a seed layer for the nanostructures growth was deposited on ITO substrate by RF magnetron sputtering method at 40 and 60 nm thicknesses. Then the TiO2 nanostructures were synthesized on the samples by keeping them floating with TiO2 layer facing down the vessel in 10M NaOH solution at 80°C for 45 min. Effect of seed layer thickness to the growth of TiO2 nanostructure and its memristive behaviour were investigated. Surface morphology and current-voltage measurement for its memristive behaviour were measured by FESEM image and Keithley 4200 semiconductor characterization system. It was found that 60 nm-TiO2 thin film result in the formation of dandelion-like morphology of TiO2 nanowires and gives better memristive behavior with larger switching loops when positive voltage was applied to the sample.

Effect of Hydrothermal Growth Temperature on the Morphology and Structural Properties of Synthesized TiO2 Nanowires

Titanium dioxide nanowires have successfully prepared by hydrothermal method. The effect of hydrothermal growth temperature on the morphology and structural properties of TiO2 nanowires have been investigated. It was observed that at low temperature of 100 °C, the formation of nanowires was at early stage, while hydrothermal treatment at 130 °C showed the TiO2 precursor acquired enough energy for formation of the nanowires. Increased the temperature to 200 °C was formed the bundle of nanowires in microsize. The diameter of nanowires increased as the temperature increased. The TiO2 nanowires produced at temperature of 150 °C and annealed at 500 °C showed highest crystallinity with anatase phase.

Electrical and Structural Properties of TiO2 Thin Film Prepared at Different Annealing Temperatures by Sol-Gel Spin-Coating Method

Titanium Dioxide (TiO2) thin films have been prepared on glass substrates by using sol-gel method and spin-coating technique. The samples have been annealed at temperatures of 350°C ~ 500oC. The electrical and structural properties of the thin films due to the changes of annealing treatment process were investigated by 2 point probes I-V measurement and X-ray Diffraction (XRD) respectively. The result show that resistivity of the thin film decreased with annealing temperatures. XRD characterization indicates crystalline structure of TiO2 thin films improved as annealed at higher temperatures.

Preparation of LaPO4 with Different Morphologies and Fluorescence Properties by Sol-Gel Spin-Coating Method

Lanthanum Phosphate (LaPO4) nanostructures thin films have been successfully synthesized by sol-gel spin coating technique from lanthanum nitrate and ammonium phosphate in ammonia solution. The procedure starting with formation of homogenous and transparent solution followed with annealing to form the LaPO4 nanostructures thin films. The films were annealed at different temperature to study its effect to the surface morphology and optical properties of the films. The phosphate particles are having near-spherical to rod-like nanostructures with an average size about 15 nm. The morphology is retained even the annealing temperature is increased. Furthermore, photoluminescence (PL) characterization of LaPO4 also was reported. The effect of annealing temperature was discussing detail. The intensity as well as optical brightness is highly dependent on anneal temperature. Fourier transform infra red spectra of films obtained are similar to the previous synthesis of phosphate. Thus, confirmed the formation of LaPO4 on the glass substrate.

Solvothermal Synthesized of TiO2 Microspheres and their Characterization

In this paper, we have successfully synthesized TiO2 microsperes by solvothermal method using titanium (IV) isopropoxide as titanium source and ethanol as a solvent. The solution was thermally treated at relatively low temperature of 150 °C for 3 hours. The as-prepared and annealed of TiO2 microsphere were characterized using FESEM, XRD and Raman spectroscopy. The diameter of the microspheres was 1-6 µm. The X-ray diffraction and Raman spectroscopy studies show that the microspheres has anatase phase.

A Comparative Study of TiO2 Nanocoated Mild Steel Surface Properties between Short and Long Sputtering Time of RF Magnetron

TiO2 nanocoated mild steel surface has been successfully prepared via 100 watt of RF magnetron sputtering by using TiO2 target and sputtering condition was performed in 80sccm argon gas. The studied was done in comparing the surface properties of TiO2 nanocoated mild steel between short term and long term sputtering time at 5 and 60 minutes, respectively. From the results, we have found that the long-term sputtering time producing good surface coating with lower surface roughness at 0.033 nm with thickness in nanometer scale is 169 nm via AFM. Through Auger study revealed that the coating attributed Ti and O elements at energy of 383.48 eV and 483.44 eV, respectively. It was also showed that the intensity of that element high at about 100k a.u. in long-term compared to 55k a.u. short-term of sputtering time. It is thus showed that producing coating depends upon manipulation of parameter in RF magnetron sputtering.

Preparation of LaPO4 Nanostructure Thin Films Using Successive Layer-by-Layer

Thins films of lanthanum phosphate (LaPO4) were fabricated on glass substrate using successive layer by layer (LbL) assembly method subsequent with furnace annealing. Lanthanum Phosphate (LaPO4) thin films were prepared through sol gel and spin coating technique from lanthanum nitrate and ammonium phosphate in ammonia solution. The surface morphology of films was studied through Atomic Force Microscopy (AFM). The images of LaPO4 films had a RMS roughness below 50 nm and showed some aggregates. With increasing layers of LaPO4, thus the surface roughness become thickest starts with range 13.926 nm to 33.020 nm. Two peaks, 448 and 465 nm is located in a blue-violet spectrum area.

Investigation of Stress and Electrical Properties of Air-Annealed and Oxygen-Annealed Aluminium-Doped Zinc Oxide Nanorod Arrays

In this research, we prepared aluminium (Al)-doped ZnO nanorod arrays on the glass substrate using sonicated sol-gel method. These nanorod arrays were annealed at 500 °C in air and oxygen environment using thermal furnace. Field emission scanning electron microscopy (FESEM) image reveals that nanorod arrays were deposited vertically aligned on the substrate. The stress characteristics of air-annealed and oxygen-annealed Al-doped ZnO nanorod arrays were investigated using Raman spectroscopy and X-ray diffraction (XRD) measurement. The electrical properties of the samples were investigated using two-probe current-voltage (I-V) measurement system. The results show that annealing atmospheres greatly influenced the stress and electrical properties of the nanorod arrays.