Journal of the Japan Society of Powder and Powder Metallurgy

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Metal oxides have been prepared with high temperature annealing for a long time. However, metal oxides are synthesized in nature at ordinary temperature and atmospheric pressure. In this study, learning from nature, metal oxides were synthesized at room temperature. This study focuses on “Formation and two-dimensional patterning of particle self-assembled structure”, “Synthesis of ceramics in aqueous solution and their two-dimensional patterning”, “Microstructure control and crystal face control of ceramics”, “Gas and odor sensors with highly active crystal faces”, and “Molecular sensors for detection of environmental toxin or cancer marker”. In particular, concept of crystal growth control and nanostructure control of metal oxides was proposed. The two-dimensional patterning of ceramic nanostructured films and particle self-assembled structure was achieved. In addition, a dendritic structure of tin oxide with metastable {101} crystal facets was developed in aqueous solution. They were applied to chemical sensors and gas sensors.

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Synchrotron X-ray multiscale tomography is a 3D imaging technique that integrates microtomography and nanotomography, enabling high spatial resolution analysis across a broad field of view. This approach allows for tracking 3D microstructural changes at multiple length scales in processes such as powder compaction, sintering, and ceramic microfracture. The heterogeneity, complexity, diversity, and hierarchical nature of powder compacts give rise to various defect types that influence product quality, reliability, and lifespan. In spark plasma sintering, defect formation and elimination are influenced by applied external stress, while internal stresses generated during differential and constrained sintering also play a critical role. Furthermore, the intricate subsurface crack networks formed by Vickers indentation highlight how heterogeneous microstructures contribute to toughening mechanisms.

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