Dependence of property, cathode characteristics, thermodynamic stability, and average and local structures on heat-treatment condition for LiNi0.5Mn0.5O2 as a cathode active material for Li-ion battery

LiNi_0.5Mn_0.5O₂ was heat-treated under high oxygen-pressure and Ar-reducing conditions, and then the cathode properties, thermodynamic stability and average and local structures were investigated. From X-ray diffraction and ICP measurements, it was found that the pristine LiNi_0.5Mn_0.5O₂ had a single phase of the layered rock-salt structure although the Ni content was slightly rich compared with the nominal one. These characteristics were kept even after the heat-treatments. Charge–discharge cycle tests clarified that the cycle performance of LiNi_0.5Mn_0.5O₂ was improved by both the reducing and oxidizing treatments. From neutron diffraction and X-ray absorption fine structure measurements, the local distortion around the transition metal, especially Ni, was supposed to be one of the important factors to determine the cathode properties. It was also found that the sample with higher thermodynamic stability exhibited better capacity retention in the discharge–charge cycle tests.     

Optical and adhesive properties of composite silica-impregnated Ca-α-SiAlON:Eu2+ phosphor films prepared on silica glass substrates

The compaction of a Eu-doped Ca-α-SiAlON phosphor powder was performed by electrophoretic deposition (EPD). The effect on the adhesion and optical properties of the silica precursor as both a binder of the powder and a filler of the air voids were evaluated. The adhesion of the silica impregnated composite film to the silica glass substrate was characterized by the tape test. The improvement of the external quantum efficiency was confirmed from the PL spectra measurement after the silica impregnation. The temperature dependence of the external quantum efficiency was also investigated in order to discuss the advantage of using the silica precursor as a binder for high-brightness LED applications.     

Particle morphology, electrical conductivity, crystal and electronic structures of hydrothermally synthesized (Ce,Sr)PO4

We focused on Sr-substituted CePO₄—i. e., (Ce,Sr)PO₄—with the monazite structure and synthesized the orthophosphates hydrothermally. As for the obtained products, we investigated the particle morphologies by SEM and electrical conduction properties by conductivity measurements. In order to estimate the crystal and electronic structures, neutron and synchrotron X-ray diffraction measurements were also carried out. As a result, it was found that (Ce,Sr)PO₄ with a single phase of the monazite structure was successfully prepared by the hydrothermal method and the substitution amount of Sr was almost equal to the nominal one. It was also demonstrated that a powder morphology of the (Ce,Sr)PO₄ depended on the synthetic conditions; i.e, concentrations of cation sources and pH of aqueous solution in the hydrothermal process. The Sr-substituted sample showed much higher conductivities than the unsubstituted one, in the same way as the (Ce,Sr)PO₄ synthesized by other methods reported previously.     

Hyperbranched poly(arylene ether phosphine oxide)s

Summary New AB₂ and A₂B monomers, bis(4-fluorophenyl)-4'-hydroxyphenylphosphine oxide and bis(4-hydroxyphenyl)-4'-fluorophenyl-phosphine oxide were prepared and converted to corresponding hyperbranched poly(arylene ether phosphineoxide)s with hydroxyphenyl and fluorophenyl end functional groups. While the dihydroxy monomer gave a low molecular weight polymer, the difluoro monomer produced a high molecular weight hyperbranched polymer. The glass transition temperature of the obtained polymers was 266°C and 230°C, and 5% weight loss temperature was 491 °C and 391 °C, respectively. The fluorophenyl-terminated hyperbranched polymer was soluble in CHCl₃, but the hydroxyphenyl-terminated polymer was not soluble in CHCl3 even though it has lower molecular weight than the fluorophenyl-terminated polymer, indicating that properties of the hyperbranched polymers markedly depend on end functional groups as well as their molecular weight. Received: 23 August 2000/Revised version: 19 October 2000/Accepted: 31 October 2000     

Joint material of aluminium and stainless steel for welding

Welding of collector pipes, flat heads, dished ends and connector pipes made with high temperature and creep-resistant steels is most often done through a combination of TIG and MMA processes. Progress in MAG techniques and the availability of high-quality welding consumables (solid wires) now also enables MAG welding of the above-mentioned connections. In order to prove the efficiency of such, the results of our own studies are presented in this article. The range of tests applied was similar to those used during standard qualification of welding technologies. Additionally, the economics of welding 16Mo3 steel butt joints using different combinations of welding processes was assessed and compared.     

Microwave synthesis of Fe-doped β-rhombohedral boron

Iron-doped β-rhombohedral boron was synthesized by 28 GHz microwave irradiation on a powder mixture of iron and β-boron. β-Boron strongly absorbs 28 GHz microwaves, and this strong coupling with microwave energy can be used to promote a reaction with iron dopant. The powder mixture was heated to 1800°C within 2 min by microwave irradiation, resulting in the formation of β-rhombohedral boron interstitially doped with iron. The reaction proceeded rapidly without accompanying grain growth. The XRD analysis and the electrical conductivity measurements revealed successful incorporation of iron into two doping sites of β-boron.     

Absorption loss coefficient of the active layer for 1.48-μm bulkand MQW lasers

It is shown that the absorption loss coefficient of the active layer for 1.48-μm bulk lasers is 66 cm^-1 which is between 45 and 107 cm^-1 for 1.3-μm bulk lasers and for 1.55-μm bulk lasers, respectively. It is also described that the absorption loss coefficient of the active layer for 1.48-μm multiple-quantum-well (MQW) lasers is 28 cm^-1 which is about two-fifths of that for 1.48-μm bulk lasers. Therefore, the high slope efficiency of the 1.48-μm MQW lasers is attributed not only to the small optical confinement factor but also to the small absorption loss coefficient of the active layer     

Forward body-bias MOS (FBMOS) dual rail logic using an adiabaticcharging technique with sub -0.6 V operation

A novel logic family for low-voltage adiabatic logic, called forward body-bias MOS (FBMOS) dual rail logic, has been proposed. This technique uses forward body-bias effects to enable non-floating output levels during the entire data valid time without increased transistor count