Advanced Materials Research Vol. 832

Abstract: Anodic oxidation of titanium (Ti), zirconium (Zr) and niobium (Nb) foils in fluoride ethylene glycol (EG) added to it 1 H₂O₂ as oxidant was done to produce oxide film with nanostructures at 40 V. Whilst arrays of aligned nanotubes were successfully formed on the surface of Ti and Zr respectively, anodic Nb₂O₅ was found to consist of nanoporous structure with pore size of ~ 20 nm. Despite long nanotubes were formed on both Ti (2 μm) and Zr (3 μm), the surface of the nanotubes suffered from severe dissolution, thinning the wall and collapsing them. Well defined, ordered surface structure of the nanotubes is required as they will be used as template for subsequent deposition of nanoparticles. This was achieved when Ti anodised in 5 ml H₂O₂ fluoride EG. With excess H₂O₂ etching at the surface occur more uniformly forming homogenous surface structure. α-Fe₂O₃ were then electrodeposited on this surface at-3 V from chloride solution and the mode of formation is believed to be due to electrogeneration of base at the surface of the TiO₂.

Abstract: Multi-walled carbon nanotubes (MWNTs) were used to prepare epoxidised natural rubber (ENR) nanocomposites. Our attempt to achieve nanostructures in MWNTs/ENR nanocomposites were formed by incorporating carbon nanotubes in a polymeric solution. Using this technique, nanotubes can be dispersed homogeneously in the ENR matrix with an attempt to increase the mechanical properties of these nanocomposites. The properties of the nanocomposites such as volume resistivity, tensile strength and tensile modulus were studied. Mechanical test results show an increase in the initial modulus for up to 14 times in relation to pure ENR. In addition to mechanical testing, the dispersion state of the MWNTs into ENR was studied by field emission electron microscopy (FESEM) and atomic force microscope (AFM) in order to understand the morphology of the resulting system. According to the present study, application of the physical and mechanical properties of carbon nanotubes to ENR can result in rubber products which have improved mechanical, physical and chemical properties.

Abstract: Abstract. Investigation on the plasma properties is an essential fundamental works in order to precisely control the growth of nanoscale thin film. In the present work, we produced and study the reactive magnetron sputtering plasma in Ar+O₂ ambient using a solid Zn target as sputter source. We evaluate the electron temperature, electron density and ion density using Langmuir probe measurement as a function of O₂ flow rate and working pressure. We found that the electron temperature increased spontaneously with the oxygen flow rate. The electron temperature was almost doubled when O₂ flow rate increased from 0 sccm to 10 sccm. The electron and ion densities increased with the oxygen flow rate between 0 sccm and 5 sccm. However, after 5 sccm of O₂ flow rate which is approximately 11% of O₂/(O₂+Ar) flow rate ratio the electron density decreased drastically. This is due to the electron attachment and the production of negative ion species in Ar+O₂ plasma environment. In addition, we found that the ion flux increase monotonically with the O₂ flow rate thus will increase the ion bombardment effect on the deposited thin film and eventually damage the thin film. Our experimental results suggest that the O₂ flow rate and the working pressure would have a significant influence on ion bombardment effect on deposited thin film.

Abstract: The aim of this paper is to discuss on the roles of plant extract in the synthesis of metallic nanoparticles. Synthesis of metallic nanoparticles has started few decades ago through physical and chemical methods. Recently, green technology through biosynthesis method has drawn great attention compared to the physical and chemical method. Biosynthesis was found to be more energy efficient and able to eliminate the use of hazardous chemicals. The biosynthesis studies involved the application of fungi, bacteria, yeast, algae and plant extract. Plant extract has several advantages since the use of microorganism required stringent control on cell culture. Furthermore, the reaction rate is much faster as compared to that of the microorganism methods. The important compounds in the plant extract are hydroxyl and carbonyl groups. Both functional groups allowed plant extract to act as reducing agent as well as stabilizing agent. Several studies have been carried out to optimize the extraction of these compounds such as plant drying technique, extraction temperature and type of extractions solvent. The common method used to quantify the concentration of reducing agents in the extract is through Folin-Ciocalteu method. Utilization of plant extract not only capable of producing well dispersed monometallic nanoparticles, but also bimetallic nanoparticles. Previous studies revealed that concentration of plant extract has significant effect on particle size and shape as well as particle distribution.

Abstract: The unlimited applications of nanoparticles in human life are increasing day by day. Nanoparticles have drawn attention among researchers from academia to industry due to its large specific surface area, high chemical reactivity, physical affinity and interesting optical, electrical and magnetic properties. These properties of nanoparticles stimulate researchers to reduce particle sizes from few sub micrometers to nanometer levels. The successful application of nanoparticles depends on the simplicity of the methods for its cost effective synthesis. Since the very beginning of nanoscience, development of simple, low cost and high yielding methods has been a challenging task. Various approaches were proposed for the commercial production of nanomaterials from solid state. However, chemical method which is complicated and expensive showed limited success in the synthesis of controlled structure nanoparticles from rare-earth solid compounds. Among all the approaches, high energy ball milling with surfactant has been widely exploited for the synthesis of various nanomaterials, nanograins, nanocomposites from solid state. Self-assembled structures of surfactants provide a valuable tool for the controlled formation of nanostructure. In this process, the dispersion and enhanced grinding of particles are achieved in the reaction centers that reside in the microstructure of surfactants. In high-energy ball milling, plastic deformation, cold-welding and fracture are predominant factors which lead to a change in particle shape, size. These result in the formation of fine and dispersed particles. Stirred ball mill grinding is advantageous for nanoparticle production over other fine grinding techniques owing to its easy operation, simple construction, high size reduction rate and relatively low energy consumption. The aim of this systematic review is to represent the basic concept and applications of mechanical milling in the surfactant assisted synthesis of various nanomaterial, nanocomposite and nanocarbon materials.

Abstract: ZnO thin films have been prepared sol gel dip coating method using zinc acetate dehydrate (Zn(CH₃COO)₂·2H₂O, Merck) as cation source, 2-methoxyethanol (C₃H₈O₂, Merck) as solvent and monoethanolamine, MEA (C₂H₇NO, R&M) as sol stabilizer. Film deposition was performed by dip-coating technique at a fixed deposition rate on Corning 7740 glass substrate. The effect of sol concentration on the properties of the thin films is discussed. The effect of the sol concentration on produced ZnO films was found to be significant. X-ray analysis showed that thin films were preferentially orientated along the c-axis direction of the crystal. Besides, the films had a transparency of greater than 80% in the visible region for sol–gels with a zinc content of up to 0.8 M and exhibited absorption edges at ~375 nm.

Abstract: Nanocrystalline zinc oxide (ZnO) thin films have been obtained by the sol gel process. A stable and homogeneous solution was prepared by dissolving zinc acetate dehydrate as a starting material in a solution of 2-methoxyethanol and monoethanolamine (MEA). The molar concentration of zinc acetate was fixed at 0.6 mol/L while the molar ratio of MEA to zinc acetate was kept at 1:1. The films were deposited by various deposition speeds by dip-coating on glass substrates, and subsequently transformed into nanocrystalline pure ZnO films after a thermal treatment. Various deposition speeds were selected as the parameter to optimize the thin films quality. The structural and optical properties of the ZnO films were studied by X-ray diffraction (XRD), UV-Vis-NIR spectroscopy, respectively. The electrical properties of the ZnO thin films were characterised by dc 2 probing system and power supply (Advantest R6243). It was found that the deposition speed affects the resultant properties of ZnO thin films.

Abstract: The intercalation of herbicide, 2,4,5-tricholorophenoxybutyrate (TBA) , into zinc-aluminium-layered double hydroxide (ZAL) for the formation of a new nanocomposite ZAT, was accomplished via anion exchange method. Due to the intercalation of TBA with ZAL interlayer domain, basal spacing expanded from 8.9Å in the ZAL to 23.3 Å in the ZAT. The percentage loading of TBA in the ZAT is 45.5 % (w/w). The FTIR spectra of the nanocomposite shows resemblance peaks of the TBA and Zn-Al-layered double hydroxide indicating the inclusion of TBA into the layered double hydroxide. Surface area of the resulting nanocomposite increased from 1.3 to 15.6 m²g^-1 with the nitrogen adsorption-desorption of type IV, indicating the mesopore type of material.

Abstract: Lead titanate thin films were successfully prepared using a simple sol-gel method. In the present study extra Pb excess was not taken into consideration in such a way that the ratio of Pb:Ti is 1:1. Different molar concentration (0.1, 0.2, 0.3, 0.4, and 0.5) involved in this study and it was found that the solutions increased in acidic level by the increment of molar concentration that being measured by pH and conductivity meter (JENWAY-3540). It also indicated that the solutions were electrically resistive at low concentration which might due to the existence of lead and oxygen ionic bonding. The solutions were then deposited onto cleaned glass substrate by spin coating technique indeed to have better thin film homogeneity at room temperature. The prepared thin films were characterized on electrical property considering the resistivity measured by solar simulator (BUKOH KEIKI EP-2000). After that structural and physical property of thin films were observed by atomic force microscopy (Park System, XE-100).

Abstract: Previous studies have shown that lead titanate (PbTiO₃) with its full potential brings out the ferroelectric property provided by its perovskite structure. It was predicted that from origination to become a modified lead titanate is most preferable, i.e. lead zirconium titanate (PZT). In the present study, PbTiO₃ thin films were made through a simple sol-gel method by using spin coating technique. The deposition of thin films was at constant rate, 100rpm/s and took about 25s to complete. The fabricated thin films were then annealed at different temperature. After that, the films thickness measurement was taken by surface profiler (KLA Tencor) and characterization on dielectric property comprised at different anneal temperature. This feature indicates the power loss that will be taken into account under ac condition. The measurement of thin films was executed at 1Hz to 1MHz by using impedance spectroscopy analyzer (Solartron S1 1260A-1296) and electrical part was measured by solar simulator (BUKOH KEIKI EP-2000).