Pressureless all-solid-state sodium-ion battery consisting of sodium iron pyrophosphate glass-ceramic cathode and β″-alumina solid electrolyte composite

In recent years, the expansion of demand for lithium ion batteries has resulted in soaring prices of the constituent resources. From the viewpoint of safety, studies on all-solid-state batteries are actively being carried out. In this study, we succeeded in driving all-solid-state batteries derived from nontoxic oxide glasses at room temperature without requiring scarce resources such as lithium and cobalt. The main structure of the ceramic batteries with a simple structure in which Na₂FeP₂O₇ crystallized glass and β″-alumina solid solution are joined by pressureless cofiring at 550°C. During the crystallization of Na₂O-Fe₂O₃-P₂O₅ glass, fusion with the β″-alumina solid solution is achieved. Reversible charge and discharge of 80 mAh/g were achieved at room temperature. It is not necessary to apply pressure during cell preparation or the use of the batteries. Furthermore, the strong junction at the cathode and electrolyte interface does not peel off during charge and discharge over a long period of 623 cycles. Ex situ X-ray photoelectron spectroscopy revealed partial Fe⁴⁺ induction and a reversible charge and discharge reaction even after overcharging to 9 V. It was demonstrated that Na₂FeP₂O₇ is very stable against overcharging to 9 V.     

Prediction of cutting forces and machining error in ball end milling of curved surfaces -II experimental verification

This paper presents the results of a series of experiments performed to examine the validity of a theoretical model for evaluation of cutting forces and machining error in ball end milling of curved surfaces. The experiments are carried out at various cutting conditions, for both contouring and ramping of convex and concave surfaces. A high precision machining center is used in the cutting tests. In contouring, the machining error is measured with an electric micrometer, while in ramping it is measured on a 3-coordinate measuring machine. The results show that in contouring, the cutting force component that influences the machining error decreases with an increase in milling position angle, while in ramping, the two force components that influence the machining error are hardly affected by the milling position angle. Moreover, in contouring, high machining accuracy is achieved in “Up cross-feed, Up cut” and “Down cross-feed, Down cut” modes, while in ramping, high machining accuracy is achieved in “Left cross-feed, Downward cut” and “Right cross-feed, Upward cut” modes. The theoretical and experimental results show reasonably good agreement.     

Pervaporation of methanol–water mixture by poly(γ-methyl L-glutamate) membrane and synergetic effect of their mixture on diffusion rate

The pervaporation behaviors of methanol–water by poly(γ-methyl L -glutamate) (PMLG) membrane at non-steady- and steady-state permeation were investigated. The values of t_1/2 (time required to reach a half value of steady-state permeation flux) for methanol and water changed and did not change with the component in feed, respectively. Both of the average diffusion coefficients for methanol–and water–PMLG from the mixture changed exponentially with the sorption amount of methanol by the synergetic effect on diffusion. The difference in behavior of non-steady and steady state diffusion was explained by whether D_o (diffusion coefficient at zero penetrant concentration) was influenced by the concentration distribution of penetrant in PMLG membrane.     

XAFS Analysis for Niobium Carbide Particle Growth on Silica Support During Preparation Process

SiO₂-supported NbC catalysts were prepared by using temperature-programmed reactions (TPR). XAFS analysis confirmed that Nb₂O₅ was reduced to NbO₂ in the first TPR stage and converted into NbC in the second TPR stage. Nb particles grew only in the second TPR stage. Formation of highly dispersed NbC particles on SiO₂ surfaces was achieved.     

Improvement of ageing properties of rubber films prepared from radiation-vulcanized natural rubber latex

Radiation-vulcanization of natural rubber latex (NRL) with n-butyl acrylate gives a higher tensile strength for films obtained after casting. The ageing properties of radiation-vulcanized natural rubber in the presence of various antioxidants have been investigated. In order to find out suitable antioxidants for radiation-vulcanized natural rubber latex (RVNRL) films, extraction of the gel fraction was carried out in xylene with 1 wt.-% antioxidant and air bubbling. Antioxidants which give less reduction in gel fraction due to oxidative degradation during extraction are effective for ageing tests of RVNRL films. It was found that tris(nonylated phenyl) phosphite (Nonflex TNP) and 2,5-di-tert-amylhydroquinone (Antage DAH), among 12 different antioxidants tested, were the most effective antioxidants for RVNRL films.     

Conditions for growth of AlN single crystals in Al–Sn flux

In this study, we investigated the Al–Sn flux system and its growth conditions to obtain AlN single crystals. AlN single crystals of a size of 50 μm were successfully grown using an Al–Sn melt under nitrogen gas pressure. The growable region of the AlN crystals was established using a pressure‐temperature diagram. The required nitrogen gas pressure for the growth of the AlN crystals was found to decrease with increasing temperature, and AlN was grown at 0.1 MPa nitrogen pressure above 1300°C. By investigating the AlN yield with various Al concentrations, we confirmed that the Al component in the Al–Sn melt facilitated nitrogen dissolution. Finally, scanning electron microscopy analysis showed that the obtained AlN particles showed good morphology.