Vanadium oxides (VOx) are among the most widely used materials that undergo a metal-insulator transition (MIT). A sharp difference in their electrical resistance is observed before and after they reach the transition temperature. A great deal of research is currently underway to apply these materials to various applications. However, vanadium oxides generally have varied phases, and thin films made of these materials often end up with a multi-phase microstructure rather than a single-phase one. Also, these thin films are not as stable as desired. This multi-phase microstructure negatively affects the electrical properties of a thin film; thus, ensuring that a single-phase microstructure is achieved is important. An analysis of those thin films as to how this multi-phase microstructure, if any, is configured is also important. In the present study, I–V measurements were conducted to identify and analyze all VOx phases present in the VO2 thin film and even those that were too small in volume to be detected by using X-ray diffraction (XRD) analysis. The experimental results were further analyzed using a space-charge-limited current model. As a result, at least two other phases, i.e., V5O9 and V2O3, were found to be present in the VO2 thin film.

Flexible electronic devices or stretchable electronic devices have recently attracted increasing attention. Organic semiconductor transistors have been intensively studied for such applications, as for the operation of display pixels and various sensors, and for use in logic circuits consisting of organic semiconductor transistors. When organic thin film transistors (OTFTs) are employed for the operation of display pixels or for use as transparent substrate-based sensors, the properties of the OTFTs may be changed by the light illuminating the OTFT from itself or from the outside, thus degrading circuit stability. In the present study, an OTFT was fabricated on a glass substrate by using pentacene, and light of different wavelengths and intensities was illuminated through the top and the bottom of device to investigate the additional photocurrent flowing through the OTFT. The experimental results showed that the photocurrent in a 100 nm-thick OTFT thin film had a symbatic pattern and that the photocurrent nonlinearly increased with increasing light intensity.

The recent development of electro-optic devices and anticorrosion media has led to the necessity to investigate infrared optical systems with solid-solid interfaces of materials that often have the characteristic of amorphousness. One of the most promising classes of materials for those purposes seems to be the chalcogenide glasses. Chalcogenide glasses, based on the Ge-Sb-Se system, have drawn a great deal of attention because of their use in preparing optical lenses and transparent fibers in the range of 3 similar to 12 um. In this study, amorphous Ge-Sb-Se chalcogenide for application in an infrared optical product design and manufacture was prepared by a standard melt-quenching technique. The results of the structural, optical and surface roughness analysis of high purity Ge-Sb-Se chalcogenide glasses are reported after various annealing processes.

The recent development of electro-optic devices and anticorrosion media has made it necessary investigate infrared optical systems with solid-solid interfaces of materials with amorphous characteristics. One of the most promising classes of materials for these purposes seems to be chalcogenide glasses, which are based on the Ge_Sb_Se system, have drawn much attention because of their use in preparing optical lenses and fibers that are transparent in the range of 3-12 um. In this study, a standard melt-quenching technique was used to prepare amorphous Ge_Sb_Sechalcogenideto be used in the design and manufacture of infrared optical products. The results of structural, optical, and surface roughness analyses of high purity Ge_Sb_Sechalcogenide glasses after various annealing processes reported.

For a single crystal wafer, due to its inherent brittleness, the surface roughness is regarded as the most critical factor in determining the strength of the chip. After a grinding process is applied to the back side, grinding traces can be left on the wafer, depending on the grinding mode. This paper is intended to evaluate the effects of grinding marks on the bending strength of chips quantitatively when the grinding marks are generated by back grinding during the course of the silicon wafer thinning process. To that end, chips were taken from wafers under different grinding conditions and the bending strength of each was then measured, depending on the direction of the bending axis and on the grinding marks. Using the AFM, surface roughness was measured in each grinding condition. In addition, after the bending strength test, the fracture behavior depending on each bending condition was analyzed. In conclusion, when polishing using grit that was less fine than number-2000 grit, the bending strengths of thinned chips were strikingly different depending on the location on the wafer. However, the chips precisely polished had a greater strength than the chips that were ground.

Chalcogenide glasses based on the Ge-Sb-Se system have drawn a great deal of attention because of their use in preparing optical lenses and fibers transparent in the range of 3-12 mu m. In this study, amorphous Ge-Sb-Se chalcogenide for an application in infrared optical product design and manufacture was prepared by a standard melt-quenching technique. Results of the structural analysis and differential scanning calorimetry of high purity Ge-Sb-Se chalcogenide glasses are reported during various annealing processes. An anomaly of crystallization was observed in the DSC result of the chalcogenide glass and the activation energy of Ge18Sb22Se60 calculated by the Ozawa method was approximately 3.2 eV.

The WC-6.5% Co and SHA (Super Hard Alloy) cladding layer was formed on the SPCC plate by electric resistance welding and investigated the microstructure with wear behavior. It was found that the WC-6.5Co cladding layer exhibited compact microstructure with rare defect due to the meted solidification of SHA by electrical joule's heat. Also, the abrasive wear resistance of the cladding layer was significantly improved as compared with fundamental welding structural steel. This study deals with characterizations of microstructure and wear performance of a cladding layer consisted of composite metal powder of fine WC-6.5%Co and Super Hardness Alloy (SHA) by the electric resistance welding. The cladding layer with two different matrixes was observed by using SEM and EPMA. The main matrix was semi-sintered structure which had been bonded with fine WC particles, binder phase of Co and melted SHA by joule heat generation. The other was the imperfect melted SHA surrounded the main matrix. The hardness of main matrix was between 1010 and 1100 HV. The hardness of imperfect melted SHA was between 600 and 670 HV. The rubber wheel abrasion test had been carried out with using silica in dry environment. Also the abrasion test for fundamental welding structure steel (SM490) and D2 under the same wear conditions was performed to confirm the significant improvement of wear performance of the cladding layer. From results of abrasion test, it was found that wear volume showed linearly increase with the increase in an abrasion load, but wear volumes were hardly changed as abrasion speed was increased for all specimens of SM490 and the cladding layer D2. In comparison by wear rate, the cladding layer showed the superior wear performance that was 15 times of SM490 and about 62% of D2. The wear mechanism of SHA was observed as indentation and sliding cutting of abrasion particles, and main matrix were found the intergranular fracture by removal of the binder phase which in turn causes undermining of WC particles and hence, ploughing out of WC particles.

Research in the field of ferroelectric materials has significantly increased in recent years because of exceptional electronic and optical properties. In this study, amorphous materials of potassium niobiate (KNbO3) for an application in an electro-optical product design and manufacture were fabricated by a Win-roller quenching method, and structural and thermal properties were studied through various post-annealing processes. Four anomalies of crystallization were observed in the DTA results of the amorphous KNbO3. The activation energies calculated by the Ozawa method were approximately 164 kJ/mol, 251 kJ/mol, 150 kJ/mol, and 216 kJ/mol. To investigate the process of crystallization structurally, the amorphous KNbO3 was post-annealed and the intermediate phase of K4Nb6O17 was found when heat-treated in the temperature range 550 degrees C to 800 degrees C before the formation of the perovskite KNbO3 phase.

Organic thin-film transistors (OTFTs) are being extensively studied for the next generation electronic devices, which will require cost reduction and flexibility. In this study, OTFTs with a double-gated structure were fabricated and their electric properties depending on main and complementary gate voltages were presented. Not only the drain currents, but also the surface potentials of pentacene films were remarkably modulated in accordance with the complementary gate field. A pMOS d-inverter circuit constructed with conventional and double-gated OTFTs was designed and fabricated, and the gain of the d-inverter measured at V (CG) = 0 V was approximately 2.8.

Porous CeO2-20 wt.%TiO2 composite powders having a homogeneous distribution and nanocrystalline were successfully synthesized by a sol-gel process using titanium iso-propoxide and Ce(NO3)3·6H2O as precursors. The particle sizes of the asreceived porous CeO2-20 wt.%TiO2 composite powders were measured in the range from 0.3 to 10 μm by SEM. As the calcination temperature was increased up to 1050 C, the porous composite powders having pores ranging from 0.1 nm to 3 μm in pore size were obtained. The pore frames of CeO2-20 wt.%TiO2 composite powders were less than 500 nm thick and they were nanocrystalline with a dense structure. From a comparison of the photocatalytic activity, the porous CeO2-20 wt.%TiO2 composite powders calcined at 900 C showed an excellent efficiency for the removal of phenol under UV light. However, in the powders calcined at 600 C, there was a relatively higher photocatalytic activity than that of other powders under visible light. Hence this sample had a strong edge band at a blue-green wavelength range.

An increasing interest in investigations of chalcogenide glasses has been observed in recent years. This interest is due to their specific properties and to the possibilities for their applications in different fields of science. The optical devices, on the basis of the photo-induced phase transition between amorphous and crystalline states in chalcogenide glasses, are possible candidates for the micro- and nano-electronics. Here, we analyzed the basic physical properties of samples of Ge-As-Se and As-Se chalcogenide glasses for planning a of chalcogenide aspheric lens. Differentiated differential thermal analysis/thermogravimetry (differentiated DTA/TG) revealed that the activation energies of the crystallizations of Ge(10)As(40)Se(50) and As(40)Se(60) were approximately 3.6 eV and 3.3 eV, respectively.

Organic thin-film transistors and inverters were fabricated with screen-printed electrodes. The screen printing ink was formulated with silver nanoparticles for high conductivity and carbon black for a high work function. Under optimum fabrication conditions, a pattern as small as 30 mu m could be fabricated. The field effect mobility p was calculated to be 7 x 10(-2) cm(2) V-1 s(-1) from the organic thin-film transistor. For this transistor, the ratio of silver nanoparticles to carbon black for screen-printed electrodes was 30 to 70 wt %. (C) 2009 The Japan Society of Applied Physics

Friction stir welding is a relatively new solid state joining process. A6061-T6 and A5052-H32 aluminium alloy has gathered wide acceptance in the fabrication of light weight structures requiring a high strength to weight ratio and good corrosion resistance. This friction stir process uses a non-consumable tool to generate frictional heat in the abutting surfaces. The welding parameters such as tool rotational speed, welding speed, etc., and tool pin profile play a major role in deciding FSP zone formation in A6061-T6 and A5052-H32 aluminium alloy. Three different tool pin profiles have been used to fabricate the dissimilar butt joints. The formation of friction stir processed zone has been analysed macroscopically. Tensile properties of the joints have been evaluated and correlated with the friction stir processed zone formation.

In a plasma display panel (PDP) as one very successful technology, a MgO thin film is used to protect the dielectric layer of an AC PDP due to its large secondary electron emission coefficient resulting in a lower firing voltage. In this study, we deposited an MgO film using a plasma-enhanced chemical vapor deposition method and identified the characteristics of the MgO film by observing its preferred orientation and surface shape in terms of substrate type and deposition variables. MgO films with good morphology and a (200) preferred orientation were obtained on Si(100), Pt/Ti/SiO(2)/Si(100), and glass substrates when the deposition temperature is approximately 270. Pt/MgO/ITO/glass and Pt/MgO/ITO/PET capacitors were fabricated and their electric properties were measured for a low temperature application such as in a flexible display.

This study deals with characterizations of microstructure and wear performance of a cladding layer, product on 1.9 mm-thick mild steel plate by the electric resistance welding, of composite metal powder of Coarse WC-6.5%Co and high carbon alloy (SHA). The cladding layer was examined and tested for microstructural features, chemical composition, hardness, and bondability. The cladding layer have two different matrix were observed by an optical microscope and EPMA. The one was the coarse WC-6.5Co structure. The other was the melted SHA with surrounding the WC-6.5Co structure. The hardness of WC-6.5Co was 1210HV. The hardness of SHA was 640HV.

Organic light-emitting devices (OLEDs) with tris-(8-hydroxyquinoline)aluminum (Alq3), which is typically a green emitter, have been studied by many researchers because of their potential for facilitating the development of flexible electronics. In this paper, the luminance characteristics, current, capacitance, and dispersion factor for degraded OLEDs, which were obtained by applying various bias currents (0.5≤IBias≤9 mA), are studied. The current dependences of lifetime were divided at approximately 2 mA, and they represented nearly linear behaviors but had different slopes in a logarithmic plot of lifetime versus ubias current. With OLEDs emitting, the anomaly of capacitance, as shown in the capacitance–voltage curve, occurred because of two factors, polarization in the bulk of organic materials and the interface between the metal and organic layers. In decayed OLEDs that had lower bias currents of less than 2 mA, it was found that the degradation of luminance was related to both the decrease in polarization and to the lowering of the injection barrier.

Classical finite element programs are not well suited to the design of composite structures, because they are primarily analysis tools and need much time for the data input and as well as for the interpretation of the results. The aim of this paper is to develop a program which allows very fast analyses and reanalyses for design process, thanks to a fast reanalysis method with changes of data and conditions. Speed in the analysis is obtained by simplification of the analysed structure and limitations in its geometrical generality and improvements in numerical methods. The use of the program is made easy with interactive user-friendly facilities.