A new electrochemical oxygen separation pump was developed by using c-axis-oriented La_9.66Si_5.3B_0.7O_26.14 (c-LSBO), which has high oxide-ionic conductivity (>10⁻³ S cm⁻¹) up to 300°C. Interfacial resistance between the electrode and c-LSBO was investigated to realize the full potential of LSBO as an oxygen separation material. The formation of a Sm-doped CeO₂ (SDC) thin film (thickness: 300 nm) between the electrode and c-LSBO was effective for suppressing the interfacial resistance. Furthermore, a mixed conductive La_0.6Sr_0.4Co_0.78Ni_0.02Fe_0.2O_3−δ (LSCFN) was applied to the electrode for enhancing the oxygen reduction/evolution activity on the electrode. The LSCFN/SDC/c-LSBO symmetric cell showed an oxygen permeation flux of 3.5 mL cm⁻² min⁻¹ (1.0 A cm⁻²) at 600°C under an applied DC voltage of 1.5 V; this value was 67 times that of Pt/c-LSBO. This oxygen pump based on the LSCFN/SDC/c-LSBO symmetric cell would find promising application in oxygen separation at intermediate temperatures. Further reduction of the interfacial resistance and polarization resistance of the electrode may decrease the operating temperatures to below 400°C.

In this study, mullite fibrous porous ceramics (MFPCs) were fabricated by freeze-drying wetted bodies formed using vacuum filtration. The effects of freezing temperatures on the microstructure and mechanical properties were investigated. The investigations revealed that freeze-drying could effectively stop silica sol migration and obtain a uniform porous ceramic microstructure in which the binder covered the fiber surfaces and bonded the fibers at nodes. Owing to the homogeneous microstructure, the compressive strength of the obtained MFPCs with open porosity of 85.4% was more than 2.0 MPa, and there were two elastic regimes and one plastic regime in the stress–strain curve of the MFPCs, moreover, which revealed that the MFPCs fractured step by step under compression. In addition, the freezing temperatures affected the properties of the MFPCs because of the formation of plates derived from the binder.

A large quantity of MgAl-layered double hydroxide (LDH) nanoparticle was successfully obtained from a single batch from high concentration (as high as 1 M) of metal salts solution. LDH were obtained by the precipitation at room temperature under ambient pressure and subsequent aging. The phase purity, crystallinity, anion composition, and morphology (shape and size of the LDH crystals) were investigated to characterize the products. Chloride type MgAl LDH with well-defined platy shapes of the lateral size of 50 nm was obtained with the very high efficiency (approximately 10 g from the 160 mL of the starting solution).

All-solid-state Li-ion battery is expected as the post Li-ion battery because of its high reliability and safety. However, the biggest issue for the all-solid-state Li-ion battery is the interfacial resistance between electrode and electrolyte rather than the bulk ionic conductivity of the solid electrolyte. In order to reduce the interfacial resistance, we recently adopted a new concept, “single-phase all-solid-state battery”, which is made of a single material. In principle, single-phase all-solid-state battery has low interfacial resistance between the solid electrolyte and electrodes, because the solid electrolyte and electrodes are same material. Here, the electrochemical properties of single-phase all-solid-state battery based on Li_1.5Cr_0.5Ti_1.5(PO₄)₃ and the effect of Li₃BO₃ additive as flux to Li_1.5Cr_0.5Ti_1.5(PO₄)₃ are shown. The pellet of Li_1.5Cr_0.5Ti_1.5(PO₄)₃ with Li₃BO₃ additive showed higher density by filling the voids of Li_1.5Cr_0.5Ti_1.5(PO₄)₃. As the result of the low electronic conductivity of Li₃BO₃, the overpotential was increased. However, the electron leakage was suppressed. On the other hand, the operation voltage and the reversible capacity were improved due to the high lithium-ionic conductivity of Li₃BO₃. It was found that Li₃BO₃ additive is useful for the improvement of the single-phase battery.

The CuFeO₂ powders have been synthesized by the microwave hydrothermal reaction at different reaction temperatures. The pure rhombohedral phase for CuFeO₂ has been formed and confirmed by the X-ray diffraction (XRD). The microstructure and morphology for all CuFeO₂ samples have been scanned by the Transmission Electronic Microscope (TEM). Various scales of grains for powders have been found spanning from several nanometers to hundreds of nanometers, and even few scales are over 1 µm for some grains. The average grain sizes for all powders have been calculated basing on the XRD patterns to show the changing of grain sizes with the temperature. The distributions of the grain size have also been studied by counting grain numbers from the TEM images. Based on the above results, the mechanism of grain growth has been analyzed and found to be the classical Ostwald ripening.

To determine whether neutrinoless double-beta decay occurs is an enormous challenge in particle physics. For this purpose, developing a highly transparent liquid scintillator that contains a candidate isotope at high concentration is required. In this work, ¹⁰⁰Mo was selected as the isotope and surface-modified nanoparticles were applied. AMoO₄ alkaline earth molybdates (A = Ca, Sr, and Ba) were synthesized with a subcritical hydrothermal method so that they were well dispersed in organic solvents. The crystalline phase of the nanoparticles was confirmed with X-ray diffraction measurements. The particle size of SrMoO₄ nanoparticles was found to be the smallest from a transmission electron microscope examination. The SrMoO₄ nanoparticles were incorporated in liquid scintillators, resulting in high transparency and efficient scintillation. In conclusion, liquid scintillators loaded with organic modified SrMoO₄ nanoparticles were successfully developed.

Inorganic surface modification was performed using a SiO₂ sol–gel technique to mitigate the fouling of alumina microfiltration membranes. A positively charged alumina membrane was coated with SiO₂ to generate a negative charge, and as a result, electrostatic repulsion prevented the serious adsorption (or deposition) of model foulants on the membrane. Upon the formation of the SiO₂ layer, small changes in the surface morphology, pore size, and surface roughness were detected. In particular, as the pore size decreased, the pure water permeability gradually decreased. When the membrane fouling was accelerated with model foulants, the highest normalized flux level and the lowest flux decline ratio (%) were observed in the smallest SiO₂-coated microfiltration membrane (0.1 M SiO₂). In summary, the SiO₂ coating contributed to the optimization of the antifouling properties of the ceramic membranes, although the pore size was reduced.

This paper presents the comparative performance of ordinary Portland cement and metakaolin-based geopolymer blocks for strontium immobilization. The geopolymer solidified blocks had better leaching resistance in deionized water, sulfuric acid, magnesium sulfuric and acetic acid buffer solutions than the cemented blocks. Meanwhile, the geopolymer solidified blocks exhibited lower compressive strength loss after freeze-thaw cycles and high-temperature tests. The more dense and compact structure of the geopolymer specimens is more beneficial for the retention of the strontium radionuclide. Most of the strontium radionuclide within the geopolymer and cement solidified blocks may be incorporated into the amorphous gels. It could be concluded that the metakaolin based-geopolymer matrix exhibited much better solidification performance and appeared to be more suitable for radioactive waste immobilization.

Electronic structures and optical properties of CuMgVO₄ and AgMgVO₄ with optimized structures were investigated using the generalized gradient approximation proposed by Perdew-Burke-Ernzerhof and the Heyd-Scuseria-Ernzerhof hybrid functional. From the energy band calculation, we found that CuMgVO₄ and AgMgVO₄ have indirect band gaps. The upper valence band is mainly composed of fully occupied Cu 3d (Ag 4d) states, and the lower is mainly comprises O 2p states. The conduction band can be divided into two regions because of the crystal-field splitting by the interaction between the V 3d and the O 2p states. The optical properties of CuMgVO₄ and AgMgVO₄ were predicted from the complex dielectric function, ε(ω) = ε₁(ω) + iε₂(ω). The static dielectric constants were estimated from the real part of the dielectric functions, ε₁(ω). The imaginary part of the dielectric functions, ε₂(ω), demonstrated optical anisotropy, with the component along the z (y) direction being larger than the others for CuMgVO₄ (AgMgVO₄) in the wavelength range of visible light. The absorption coefficient I(ω) was also calculated from the dielectric function.