Functional Materials and Devices

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Authors: Abdul Hadi, Iskandar Idris Yaacob, Lee Seok Ling
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.
Authors: N. Kancono, H.B. Senin
Abstract: Charge transfer complexes (CTC) can be readily introduced into materials by cohydrolysis-copolymerisation of bis-silylated ter-thiophenes as precursors with TMOS and TEOS in the presence of TCNQ. CTC formation is shown in the visible spectrum of the xerogel by the band at 850 nm characteristic of the TCNQ·- radical anion. Vibrational spectra have shown that strong vibration of C≡N bond at 2184, 2120 and 1595 cm-1 as peaks characteristics of CTC. The CTC bands are weak and the complex is easily destroyed by washing with acetone, which removes the TCNQ. The gelification effect of the charge transfer complexes on the hybrid materials of 2,5’’- bis(trime thoxysilyl)terthiophene/TCNQ/ TMOS showed that the peak with distance of more than 11.68 Å, formed by precursors and matrices, as a lamellar structure. The birefringence of xerogel BTS3T in presence of alkoxysilane showed that the value is near the detection limit of 0.1 – 0.4 x 10-3, which is weaker than BTS3T / THF with the birefringence value of 4.5 x 10-3.
Authors: C.K. Tan, Azlan Abdul Aziz, Hassan Zainuriah, F.K. Yam, C.W. Lim, A.Y. Hudeish
Abstract: The Current-Voltage-Temperature (I-V-T) characteristics of single layer deposition, consisting of Zr, Ti, or Cr/p-GaN Schottky diodes were determined in the temperature range 27- 100oC. Sputtering method was used for deposition of these metals on p-GaN. Analysis of the measured characteristics at room temperature allows the determination of the electrical parameters, the saturation current Io and the ideality factorη. The barrier heights and effective Richardson coefficients were determined through activation energy plot. It was found that pinning of Fermi level occurred for these metal contacts on p-GaN with the carrier concentration of 5.6x 1017 cm-3, where the Schottky barrier heights of Zr, Ti, or Cr/p-GaN are determined to be in the same range (~0.87eV).
Authors: Shahrum Abdullah, Muhamad Rasat Muhamad, K.A. Sekak
Abstract: The effects of Indium doped on Porous Silicon Nanostructure (PSN) have been studied. The Electroluminescence studies on Indium-doped porous silicon nanostructure (In:PSN) are presented. The main objective of this paper is study the EL effects of Indium doping on PSN. Porous silicon nanostructure layers have been formed by anodically etching unpolished p-type Si [100] wafer with surface resistivity of 1-10 ohm cm-1 in Hydroflouric (HF) solution at 1:1 ratio of Ethanol. Indium (In) was doped on PSN using cathodic electrodeposition composed of InCl3 and ethanol electrolythe. A diode structure has been fabricated comprising semi-transparent Au/In:PSN/p-Si substrate/Al ohmic contact electrode to observe the EL spectra. The In:PSN device shows increasing on EL and PL Intensity as well as blue-shift EL and PL spectrum is observed. Possible reasons for the enhancement will be discussed. Technological application of PSN as a light emitter would have significant impact on numerous technologies such as display panels or integrated circuits with optoelectronic devices (IO) on board and sensors.
Authors: Ismail Zainol, Mohamad Ibrahim Ahmad, Fadzil Ayad Zakaria, Anita Ramli, Haslan Fadli Ahmad Marzuki, Azlan Abdul Aziz
Abstract: The cure process and the mechanical properties of liquid polymethylmethacrylate grafted natural rubber (LMG30) modified epoxy have been studied. Addition of LMG30 significantly increased the fracture toughness and the impact strength of the epoxy resin. The fracture toughness increased up to 22 fold (17.3 MNm-3/2) when modified with 5 phr LMG30. The glass transition temperature however, decreases as the rubber content increases. The SEM analysis shows uniform dispersion of rubber particles within the epoxy matrix with average particle size between 0.4 to 0.8 0m in diameter.
Authors: Azizah Hanom Ahmad, Ri Hanum Yahaya Subban, R. Zakaria, A.M.M. Ali
Abstract: A series of experiment has been carried out to study the electrochemical performances of lithium primary cells using different cathode materials. The cathode material was made of metal oxide, electrolyte, activated carbon, and PVdF with a wt. ratio of 60: 20:10:10. PVdF was added as a binder. The metal oxides used are MnO2 and V2O5. The anode was made up of lithium metal and LiI-Li2WO4-Li3PO4 compound is used as an electrolyte. In this work the open circuit voltage (OCV) of Li/MnO2 and Li/V2O5 obtained is about 3.0 V and 3.2 V respectively. This shows that LiI-Li2WO4-Li3PO4 compound is lithium ion conductor. Lithium cell showed better performance at 100º C than at room temperature. Among these two types of cells investigated, cell Li/V2O5 worked better than the Li/MnO2 cell at room temperature and at 100°C as this cell exhibits the longest continuous discharge time and the highest OCV.
Authors: Z.H.Z Abidin, K. Ramesh, R.M. Taha, R. Puteh, A.K. Arof
Abstract: The corrosion protection property of the coating consisting of acrylic resin mixed with curcumin and dammar was investigated by immersing in 3% NaCl solution using potential - time measurement. The investigation was performed until corrosion occurred at the coating and substrate interface. As the coating degraded the penetration of electrolyte, the potential value of the coated sample decreases to a value of – 0.65 V. In this study the coating with pigment volume concentration of KC30% can withstand against corrosion by 3% NaCl solution.
Authors: Surina Othman, F.K. Yam, Abu Hassan Haslan, Hassan Zainuriah
Abstract: In this study, we investigated the contact characteristics of bi-layer thin films, Ag (200nm)/Ti (100nm) on Si-doped n-type Al0.27Ga0.73N film grown on sapphire substrate. The contacts were annealed at different temperatures (400°C-800°C) for 10 min in N2 ambient. The effects of cryogenic cooling immediately after heat treatment for improving ohmic behavior (I-V linearity) of the samples were reported. Specific contact resistivity, ρc, was determined using transmission line method (TLM) via current-voltage (I-V) measurements. Scanning electron microscopy (SEM) measurements were carried out on the as-deposited, annealed (N), and annealed-and-cryogenically (N+C) treated contacts where the surface morphology of each of these conditions were compared. In addition, measurement of the samples by atomic force microscopy (AFM) was taken in order to characterize the surface morphology.
Authors: S.A. Mohamad, M.H. Ali, Z.A. Ibrahim, A.K. Arof
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.
Authors: Z.H.Z Abidin, R.M. Taha, R. Puteh, A.K. Arof
Abstract: In this work, lawsonia pigment obtained from Henna leaves was mixed with acrylic resin and a mixture of acrylic and dammar resins (RD50%) to form two paint systems BC30% and BDP30%. The two paint systems were characterized by potential-time measurements, impact resistance, glass transition temperature (Tg) and cross hatch tests.

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