The garnet-type Li₇La₃Zr₂O₁₂ (LLZ)-based oxides have attracted attention as a solid electrolyte for next-generation all-solid-state lithium secondary batteries because of its relatively high ionic conductivity and high chemical stability toward Li metal. Producing densified garnet-type solid electrolytes at rather lower sintering temperature is an important target, which can prevent not only the lithium loss (controlling chemical stoichiometry) but also make it more compatible with cathode electrode materials. The use of sintering additives for enhancing the densification and microstructure of high ionic conductive garnet-type solid electrolytes is reviewed. Sintering additives can modify the grain and grain boundary, both contributing to the improving of the chemical and electrochemical properties of garnet-type solid electrolytes.

The dispersibility and wettability of the powder can be possible to measure by pulse NMR. The characteristic is being able to measure with good reproducibility in a short time without diluting. As a concrete measurement example of dispersibility, we compared with the particle size distribution measurement depending on the dispersion time on low concentration carbon nanotubes. Which was about 0.02%. Next, we compared the graphene dispersion sample from 10% to 50% by pulse-NMR and diluted sample by laser diffraction measurement. In the example of comparing the results in the diluted state have good correlation. However, in the case of different concentrations, there was no correlation. In addition, as a concrete evaluation example of wettability, surface treatment of powder was performed, and the difference in wettability to pure water and hexane were compared. Furthermore, an example was shown in which the wettability to the resin was also compared. Although it only shows simple applications, we think this valuation method has a high potential by the user’s idea.

With the recent remarkable development of information and communication technology, the “Fourth Industrial Revolution” is just about to take place. The fourth industrial revolution brings about a drastic change in manufacturing through cyber-physical systems. The cyber-physical system is referred to as the digital twin. The use of the digital twin will be indispensable in the trend toward high-mix low-volume production and mass customization. Undoubtedly, computer simulation will play an important role in the construction of the digital twin. The digital twin-based manufacturing will be used in powder products exactly. To construct the digital twin of the powder process, the Discrete Element Method will be employed, herein a highly efficient computational model, a computational model with high reproducibility of realistic phenomena, and reflection from the real world are required. In addition to developing computational models, analysis of big data in cyberspace and development of surrogate models are necessary as well. From the background, this paper aims to show my latest studies regarding the core technologies for the digital twin.

Vanadium dioxide, VO₂, undergoes the phase transition from monoclinic to tetragonal with property change from semiconductor to metal, respectively, at about 68°C. Metallic tetragonal structure reflects infrared light, and semiconducting monoclinic structure transmits it, leading to the thermochromic smart window. On the other hand, the phase transition temperature is slightly higher than the room temperature and can be lowered by tungsten or the other metal cation doping. Furthermore, VO₂ nanoparticles with lower transition temperature and particle size less than 100 nm is essential for the smart window because the light scattering can be dramatically suppressed by reducing the particle size to obtain a high transparency. In this study, we tried to control the particle size and the phase transition temperature of VO₂ nanoparticles by the microemulsion method from the molecular-designed precursors. The resultant VO₂ particles were characterized by XRD, DSC, SEM. Primary particle size of the resulting VO₂ nano-particles was estimated to be 37 nm with average aggregation size of about 200 nm. The phase transition temperature for the W doped VO₂ was 24°C. As a result, we successfully synthesized the VO₂ nanoparticles for smart window with controlled particle size and phase transition temperature by microemulsion method.

After preparing SiO₂-BaTiO₃ particles with core–shell structure using metal alkoxide method, we attempted to prepare a homogeneous BaTiO₃ coating layer by molecular design of a BaTiO₃ precursor solution used in the coating process. The molecular design was achieved by controlling the steric hindrance of the metal alkoxide. The molecular design effect on the coating process was investigated using transmission electron microscopy (TEM) and energy-dispersive X-ray spectrometry (EDS) with a scanning electron microscope (SEM). Results show that the coating process comprised the wettability of the alkoxide precursor solution to the core particles and the chemical reactivity of the alkoxide precursor solution. Additionally, we inferred the wettability of the alkoxide precursor solution as a major factor affecting the coating process.