We have synthesized PtxNiy alloy nanodendrites by a thermal decomposition method. The structure and composition of the as-prepared samples were characterized by field-emission transmission electron microscopy (FE-TEM), energy dispersive X-ray (EDX) spectroscopy, and X-ray diffraction (XRD). The growth mode of the PtxNiy alloy samples synthesized as a function of an intended atomic fraction of Ni was likely to be strongly affected by and reduction (or oxidation) potentials and surface energy.
The diamond wire sawing method to produce silicon wafers for the photovoltaic application is still a new and highly investigated wafering technology. This technology, featured as the higher productivity, lower wear of the wire, and easier recycling of the coolant, is expected to become the mainstream technique for slicing the silicon crystals. However, the saw marks on the wafer surface have to be investigated and improved. This paper discusses the removal of saw marks on diamond wire-sawn single crystalline silicon wafer. With a pretreatment step using tetramethyl ammonium hydroxide ((CH3)4NOH, TMAH) and conventional texturing process with KOH solution (1 % KOH, 8 % IPA, and DI water), the saw marks on the surface of the diamond wire-sawn silicon wafers can be effectively removed and they are invisible to naked eyes completely.
ZnO nanoparticles were synthesized by aqueous preparation routes of a precipitation and a hydrothermal process.
In the processes, the powders were formed by mixing aqueous solutions of Zn-nitrate hexahydrate (Zn(NO3)2 · 6H2O) with NaOH aqueous solution under controlled reaction conditions such as Zn precursor concentration, reaction pH and temperature. Single ZnO phase has been obtained under low Zn precursor concentration, high reaction pH and high temperature. The synthesized particles exhibited flakes (plates), multipods or rods morphologies and the crystallite sizes and shapes would be efficiently controllable by changing the processing parameters. The hydrothermal method showed advantageous features over the precipitation process, allowing the precipitates of single ZnO phase with higher crystallinity at relatively low temperatures below 100 o C under a wider pH range for the Zn precursor concentration of 0.1~1 M.
In this study, new composition of orange color pigment was developed by replacing formerly used lead and chromium with environment-friendly elements. TiO2-SnO-ZnO composite was synthesized using the solid state reaction under the reducing atmosphere with the LPG and air mixture gas. The synthesized pigments were characterized by spectrophotometer, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). The colorimetric analysis of pigments exhibited color values ranging from yellow to orange-red. Five different crystalline phases were formed after the heat treatment for 4 and 6 hours. The color of pigments was strongly influenced by the crystalline structure of SnO2, having either cubic or tetragonal structure. The oxidation state study of elements revealed that the color of pigment is getting close to rYR with the increase of Sn 4+ ratio.
In this work, the SiC powders were synthesized through the carbonized matter from the mixture of silica powder and rice husks. The SiC powders, obtained from the carbothermal reduction reaction of silica and carbonized rice husks, were investigated by XRD patterns, XPS, FE-SEM and FE-TEM. In the XRD patterns, the specimens showed clearly very high strong peak of (111) plane near 35 o as well as weak (220) and (311) peak respectively at approximately 60 o and 72 o . Under Ar atmosphere, the power synthesized from the mixture (in case of mixing ratio, 6 : 4) of carbonized rice husks and silica showed mainly cubic SiC crystalline phase showing relatively lower ratio of hexagonal phase without residual carbon in XRD pattern. In the TEM analysis, the specimen, synthesized from carbonized rice husks and silica with mixing ratio of 6 : 4 under Ar atmosphere, showed relatively fine particles under 5 μm and a crystalline SiC phase of (100) diffraction pattern.
Characteristics of SrAl2O4: Eu2+, Dy3+ phosphorescent phosphors synthesized by solid state reaction and polymerized complex method were comparatively analyzed. In order to evaluate thermal stability of SrAl2O4: Eu2+, Dy3+ phosphorescent phosphors at high temperature, phosphorescent properties of SrAl2O4: Eu2+, Dy3+ were investigated with thermal treatment at 1250oC under reducing atmosphere, which was the general heat treatment conditions for ceramic manufacturing process.
The phosphorescent properties of thermally treated SrAl2O4: Eu2+, Dy3+ phosphors synthesized by solid state reaction and polymerized complex method were investigated. The crystal structure and crystallite size were observed through XRD analysis. Microstructure and particle size of thermally treated SrAl2O4: Eu2+, Dy3+ phosphors were analyzed by SEM and PSA. Photoluminescence and afterglow characteristics of thermally treated SrAl2O4: Eu2+, Dy3+ phosphorescent phosphors were measured by spectrofluorometer.
Ceramic pigments, which show good thermal and chemical stabilities, have been applied for various industry with development of digital printing technology. Ceramic inkjet printing has advantages of high efficiency of ink usage and eco-friendly process. Thus, the interest of the ceramic pigments with various function and color including CMYK (cyan, magenta, yellow, black) digital primary color is increasing. Here, we investigated the thermal and chemical stabilities of white ceramic pigment for digital inkjet printing process. The microstructure and crystal structure of MgO, Al2O3, MgAl2O4, CeO2 were analyzed, and the stability with glaze were evaluated. In order to evaluate the applicability for digital inkjet printing, the chemical stability of white ceramic pigments at high temperature was investigated by characterization of the mixed color properties with CMYK ceramic pigments after firing process.
Foam reaction injection molding (FRIM) is a widely used process for manufacturing polyurethane foam with complex shapes. Numerical model for polyurethane foam forming reaction during FRIM process has been intensively investigated by a number of researchers to precisely predict final shapes of polyurethane foams. In this study, we have identified a problem related with a previous theoretical model for polyurethane foam forming reaction. Thus, previous theoretical model was modified based on experimental and computational results.