Abstract: In recent decades, a new magnetic sensor based on magnetoresistance effect is highly researched and developed intensively. GMR material has great potential as next generation magnetic field sensing devices. It has also good magnetic and electric properties, and high potential to be developed into various applications of electronic devices such as: magnetic field sensor, current measurements, linear and rotational position sensor, data storage, head recording, and non-volatile magnetic random access memory. GMR material can be developed to be solid state magnetic sensors that are widely used in low field magnetic sensing applications. A solid state magnetic sensor can directly convert magnetic field into resistance, which can be easily detected by applying a sense current or voltage. Generally, there are many sensors for measuring the low magnetic field, such as: fluxgate sensor, Hall sensor, induction coil, GMR sensor, and SQUID sensor. Compared to other low magnetic field sensing techniques, solid state sensors have demonstrated many advantages, such as: small size (<0.1mm2), low power, high sensitivity (~0.1Oe) and good compatibility with CMOS technology. The thin film of GMR is usually prepared using: sputtering, electro deposition or molecular beam epitaxy (MBE) techniques. But so far, not many researchers reported the manufacture of thin film of GMR by dc-Opposed Target Magnetron Sputtering (dc-OTMS). In this paper, we inform the development of GMR thin film with sandwich and spin valve structures using dc-OTMS method. We have also developed organic GMR with Alq3 as a spacer layer.
Abstract: Addition of power plant ash particles, classified as cenosphere and precipitator fly ashes, and bottom ash, to Al foams resulted in different foamabilities and foam structures. These distinctions arise from a difference in physical and chemical characteristics of ash particles. The cenosphere fly ash is hollow, whilst the precipitator fly ash is dense. The bottom ash is also dense with irregular shape. The major chemical constituents of these ashes are SiO2, CaO, Al2O3 and Fe2O3. It is found that the improvement in foam expansion and structure is obtained from the addition of precipitator fly ash or bottom ash particles. The addition of cenosphere fly ash, however, leads to a decrease in foamability and non-uniform foam structure.
Abstract: In this research work, physical and optical properties on glass prepared from rice husk ash (RHA) doped with MnO2 glasses were in investigated. RHA was sintered at 1,000 °C and use as a silica source for glass production. The glass sample were prepared and doped with different concentrations of MnO2 ranging from 0.0 to 1.0 mol%. The results are shown that the colors of glass samples were altered from colorless to brown with increasing of MnO2 concentration. Refractive index and density were increased with increasing MnO2 concentration. The absorption peaks at 440 nm were obtained for all Mn doped glasses.
Abstract: Titania (TiO2) thin films have been deposited using d.c. reactive unbalance magnetron sputtering on unheated substrate by various different oxygen partial pressures while working pressure and sputtering power were kept constant. A pure metallic titanium disk was used for sputtering target in atmospheric of the mixture gases between argon and oxygen. The X-ray diffraction (XRD) and atomic force microscopy (AFM) were used for characterization of characteristics structure and surface morphologies of the films, respectively. The optical transmission of the films were measured by spectrophotometer. The photocatalytic activities of the films were investigated from measurement of methylene blue degradation by using absorbance value after UV irradiation for 6 hr. The results show that the crystalline structures of the films showed the presence of single-anatase phase and mixed-anatase/rutile phase of TiO2 thin films. The surface morphology and photocatalytic activities of the films depend on oxygen partial pressure that grains size, surface roughness and thickness of the films were deceased when increasing oxygen partial pressure due to poisoning phenomenon and the high reactive gases. In addition, it was found that all TiO2 thin films were deposited by different oxygen partial pressure exhibit a good transparentness. Moreover, it was found that the TiO2 thin films deposited by used low oxygen partial pressure and single-anatase phase exhibited the best photocatalytic activity.
Abstract: The new Y257 superconductor in YBaCuO family was synthesized by standard solid state reaction. The Y257 samples were measured the critical temperature (Tc) by the four-probes method that found at 90 K. The XRD technique and FULLPROF program were used to determine the lattice parameters, space group and phase compositions. It was found that the Y257 exhibited in both of superconducting and non-superconducting phase. The Pmmm space group was fit well on superconducting phase with the lattice parameters as a=3.8108 Å, b=3.8544 Å and c=26.4967 Å. The non-superconducting phase exhibited in two space groups of Pccm (a=12.9770 Å, b=20.54780 Å and c=11.3530 Å) and Im-3m (a= 18.2104 Å, b=18.2104 Å and c=18.2104 Å). The peritectic temperature at 976.73°C was measured by differential thermal analysis.
Abstract: The new superconductors of Y-based compound, Y7Ba11Cu18Oy(Y7-11-18), has been discovered by solid state reaction with the different ratios of raw materials. All obtained samples were analyzed and characterized by XRD and the FULLPROF program. The lattice parameters of Y7-11-18 were a=3.8268 Å, b=3.8810 Å and c= 69.8794 Å. The Y7-11-18 showed the sharp transition curve of resistivity (ρ) at the critical temperature (Tc) =94 K. The doping of Y2BaCuO5 (Y211) showed that the higher Y211, the lower Tc and c lattice parameter. The SEM and EDX micrographs showed the grain size about 1-5 μm and without impurities. The DTA analysis resulted the decreasing of peritectic temperature from 962.74 °C by the higher Y211 contents.
Abstract: A green pigments based on a Cr2O3-Al2O3-V2O5-TiO2 composition have been synthesized and the ability of these pigments used with ceramic glazes to confer high solar reflectance has also been studied. Cr2O3 is the host component and the adding mixtures of Al2O3, V2O5 and TiO2 as the guest components. The composition denoted by T1 composes of Cr2O3, TiO2, Al2O3 and V2O5 are 80, 4, 14 and 2 wt%, respectively, gives near infrared solar reflectance of 82.8%. T1 green pigments were prepared for ceramic cool tile roofs (denoted by T1 cool roof). The comparison study on the effectiveness of T1 ceramic cool roofs and a commercial ceramic cool tile roofs (denoted by C cool roof) show that the T1 cool roof has given a better result by keeping the tested room about 4 °C cooler.
Abstract: Ag/ZnO powders were synthesized through a precipitation method, using poly(ethylene oxide)-block-poly(propylene oxide) as stabilizer. X-ray diffraction patterns of all prepared powders showed a mixed phase of Ag and ZnO. The existence of metallic Ag on the surface of all prepared ZnO powders was confirmed by X-ray photoelectron spectroscopy. Their photocatalytic activities were investigated through the degradation of a methylene blue solution under blacklight illumination. The Ag/ZnO prepared from the Zn2+ solution containing 7 mol% of Ag+ had the highest photocatalytic activity and this also showed better photocatalytic activity than a commercial ZnO powder.
Abstract: ZnO and La-doped ZnO nanoparticles were synthesized by precipitation method by using Zn (CH3COO)22H2O, (CH2)6N4, (PEO)128-(PPO)54-(PEO)128 and LaCl3H2O as zinc source, precipitating agent, capping agent and dopant, respectively. The calcined samples exhibited a hexagonal wurtzite structure. The smallest particle size of pure ZnO nanoparticles of about 88 nm was obtained when 0.7 mmol (PEO)128-(PPO)54-(PEO)128 was used. The particle size of La-doped ZnO nanoparticles increased when La concentrations increased. The La-doped ZnO nanoparticles showed the energy band gap between 3.159-3.222 eV.