Although metallic glasses have excellent and unique mechanical properties such as high strength, elastic modulus and hardness, they exhibit a poor ductility for the industrial use. Especially in the relaxed metallic glass due to processing or insufficient cooling rate during a manufacturing process, mechanical embrittlement occurs drastically. Therefore, controlling of the relaxation state in metallic glass has been widely evolved by thermal and physical processes. The authors have reported that the less relaxed state can be recovered (rejuvenated) using a thermal process and the rejuvenated metallic glasses actually exhibit the mechanical softening with improved plasticity. Recently, the gradient distribution of rejuvenated structure can be obtained in the cylindrical metallic glass sample using the newly developed asymmetric heat treatment equipment. In such the unique structure, the shear band angle is sensitive to the relaxation state (i.e., amount of local free volume), which develops the formation and propagation of shear band in a very complex manner during the deformation process. As a result, an intrinsic work hardening and an improvement of plastic strain in metallic glass are observed. The results provide a novel way to control the relaxation state functionally and beneficial information on the industrial application of metallic glasses.

Solidification microstructure in Fe-based Fe-X-based metallic glasses (X = Cu, Ag, Au, Pd, Pt, Rh, Ir, Ru, Os, Re, Hg) (X is a noble metallic element) with liquid phase separation (LPS) was categorized. Only Fe-Cu-based and Fe-Ag-based metallic glasses with liquid phase separation were reported among Fe-X-based alloys. Fe-P-C-Ag immiscible metallic glasses which showed liquid-phase separation were designed using the alloy parameters of mixing enthalpy, the ground state diagrams constructed by the Materials Project, and Calculation of Phase Diagrams (CALPHAD). Macroscopically separated ribbons composed of FCC-Ag entangled ribbons and Fe-P-C metallic glass ribbons were obtained by a melt-spinning method. The formation mechanism of the macroscopically separated ribbons in Fe-P-C-Ag immiscible metallic glasses is described with LPS behavior and melt-spinning process in this study.

The effect of self-assembled barium titanate (BT) aggregates in polyvinylidene fluoride (PVDF) matrix on the α‐β phase transition was investigated. The self-assembled BT/PVDF composites were prepared with and without dispersant in the self-assembled process. The addition of dispersants increased the average secondary particle area (S) of the BT particles and promoted the BT/PVDF/BT hetero-interface. FT-IR showed that the α‐β phase transition of the composites enhanced with increasing S. The Cole-Cole plot was estimated the existence of orientation polarization and interface polarization. According to these results, we proposed a BT/PVDF/BT hetero-interface model based on the double Schottky barrier model.

Tantalum oxide nanoparticles were synthesized by a thermal CVD method using tantalum (V) ethoxide as a raw material for photocatalytic applications. Their characteristics were compared with those synthesized by a conventional hydrolysis method using same raw material. The CVD process with a set temperature of 700°C produced the nanoparticles with single crystal, small average particle size (APS) of 13 nm and necking at the edge of each nanoparticle, giving high specific surface area (SSA) of 46.5 m²/g. Computational fluid dynamics revealed that the nanoparticles were formed in the carrier gas at 530-610°C and 15 kPa in the reactor. On the other hand, conventional hydrolysis method with calcination temperature of 800°C offered the lump of tantalum oxide nanoparticles with strong aggregation, much larger APSs (32 nm) and much lower SSAs (10.1 m²/g). Evaluation of photocatalytic water splitting activities under ultraviolet irradiation (λ > 200 nm) for both the nanoparticle loaded with RuO₂ as a co-catalyst showed the stable stoichiometric decomposition of H₂O into H₂ and O₂. The CVD-derived nanoparticles gave higher decomposition rate by ≈58% than that synthesized by the hydrolysis method, which was contributed to higher SSA due to characteristics of nanoparticles necking only at the edges.

This study investigated the conditions for zeolite synthesis from waste concrete powder (WCP) using the hydrothermal synthesis method. The WCP was prepared by milling the waste concrete using pot mill equipment. The synthesis conditions, i.e., the heating time, heating temperature, and NaOH solution concentration were varied. Furthermore, hydrochloric acid-treated WCP (WCP-HCl), which is removed the calcium component, was prepared to examine the effectiveness of acid treatment in the zeolite synthesis. The zeolite synthesis was investigated using X ray diffraction (XRD) and scanning electron microscopy (SEM). Analcime-type zeolite was synthesized using WCP and WCP-HCl. The requirements of synthesis conditions for analcime were as follows: heating time above 12 h, heating temperature above 433 K, and NaOH solution concentration above 2 mol/L. With a progressive increase in the concentration of the NaOH solution from 5 to 7 mol/L, analcime could be synthesized at NaOH concentrations below 4 mol/L, while cancrinite was synthesized at NaOH concentrations exceeding 5 mol/L. The peak intensity of analcime and cancrinite of WCP-HCl showed high value in comparison to the WCP. Thus, the effectiveness of the HCl treatment of WCP was confirmed from the XRD patterns.