Although the binary Al–Ir cubic quasicrystalline approximant has been expected to be a narrow-gap semiconductor, it has not yet been produced because the presence of Al site vacancies causes excess hole doping. We suggest that high-pressure synthesis (HPS) can effectively reduce these vacancies. In this work, we investigated how HPS affected the structural and thermoelectric properties of an Al–Ir quasicrystalline approximant, finding that the sample made by HPS had a larger Seebeck coefficient than a sample made by conventional spark plasma sintering (SPS). Further, applying high pressure increased the lattice constant and measured Al composition by increasing the number of Al atoms in the Ir₁₂ icosahedral cluster. These results show that HPS suppressed vacancies in the cluster, which doubled the dimensionless figure of merit zT.

 

This Paper was Originally Published in Japanese in J. Thermoelec. Soc. Jpn. 16 (2020) 139–143.

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An increased number of vacant houses have been found in Spain and Japan in recent years, specifically in de-growth areas. This article explores the extent to which these two countries have promoted policies and tax systems to counteract this phenomenon. According to existing research, tax systems sometimes work as factors that encourage the increase of vacant houses. However, the systems in the two countries in question are dissimilar. We apply the divergence perspective for developing housing system typologies, and analyse vacant housing policy measures from the administrative perspective of Japan’s centralised unitary and Spain’s decentralised unitary state.

As a result, while the Spanish taxation system may expect housing owners to circulate their properties in the real estate market, the duty schemes in Japan encourage homeowners to build or to hold onto their houses. Moreover, the recent vacant housing policies of both countries seem to actively decentralise taxation authorities, disclose information on vacant properties and take advantage of vacant spaces. More generally, vacant housing control in Spain is relevant to countries with decentralisation or even a federal system, which can control housing vacancy levels by the power of local governments. By contrast, the Japanese method of

applies to East Asian and socialist countries, where national governments can promptly implement policies. Moreover, the policy promoting a nationwide vacant house bank would help to mitigate information asymmetry.

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Although the binary Al-Ir cubic quasicrystalline approximant (QCA) has been expected to be a narrow gap semiconductor， it does not realize due to large amount of aluminum sites vacancies leading to excess hole doping. We suggest that a high-pressure synthesis (HPS) is effective to reduce vacancies. In this work, effects of HPS on structural and thermoelectric properties were investigated for an Al-Ir QCA. We found that the Seebeck coefficient of a sample made by HPS has a larger value compared to that sintered by using conventional spark plasma sintering (SPS). Further， the lattice constant and the analyzed aluminum composition increased as high pressure applied due to increasing the number of Al atoms in the Ir-12 icosahedral cluster. These results indicate that HPS suppressed vacancies in the cluster leading to a 2 times higher value of zT.

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This study aims to make clear the vacancy controllability of inverse opal structure fabricated by patterned and repeated dip-coating The process consists of two steps of coating The first one is fabrication of sacrificial particles assembly, silica in this case The second one is fabrication of nano-particles for shell-structure around the sacrificial particles After these processes, silica particles were selectively dissolved to fabricate inverse opal or porous structures It was made clear that vacancy of inverse opal can be controlled by changing particle diameter We also demonstrate the fabrication of patterned inverse opal structure by using hydrophilic/hydrophobic patterned substrate

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MgO, Mg₂SiO₄, and MgO/Mg₂SiO₄ nanostructures were synthesized, and their luminescence properties were investigated. The morphological and structural properties of the MgO nanostructures were also characterized. Sponge-like MgO particles with layered nanosheet structures were synthesized by thermally annealing MgCl₂ in air. The MgO nanostructures exhibited a cathodoluminescence emission peak at 5.2 eV with a small peak at 2.4 eV. The Mg₂SiO₄ and MgO/Mg₂SiO₄ nanostructures were also synthesized by annealing MgCl₂ with CaSi₂. Mg₂SiO₄ domains were formed on the surface of the MgO particles. Two main emission peaks were observed for the MgO/Mg₂SiO₄ nanostructures—one at approximately 5.2 eV and another in the range of 2.4–3.4 eV. Compared to MgO, the photoluminescence characteristics of the MgO/Mg₂SiO₄ nanostructures were modified, and the emission peaks were shifted. The formation of Mg₂SiO₄ with MgO expanded the visible–ultraviolet emission regions from 2.4 to 3.4 eV under cathode-ray excitation, followed by a shift from 2.1 to 2.0 eV under photo excitation.

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In challenging a direct observation of the vacancy in crystalline silicon, we have carried out low-temperature ultrasonic measurements down to 20 mK. The longitudinal elastic constants of non-doped and B-doped crystalline silicons, which were grown by a floating zone (FZ) method in commercial base, reveal the elastic softening proportional to the reciprocal temperature below 20 K. The applied magnetic fields turn the elastic softening of the B-doped FZ silicon to a temperature-independent behavior, while the fields up to 16 T do not affect the elastic softening of the non-doped FZ silicon. We present a plausible scenario for this result. Namely the vacancy with the non-magnetic charge state V⁰ in the non-doped silicon and the magnetic V⁺ in the B-doped silicon is responsible for the low-temperature softening of the shear elastic constants (C₁₁−C₁₂)⁄2 and C₄₄, which can be described in terms of the quadrupole susceptibility due to the Jahn–Teller effect.

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This study focuses on electrochemical potential control and fabrication methods for various metal complexes and polycyclic aromatic hydrocarbons at solid–liquid interfaces, particularly using electrochemical scanning tunneling microscopy (EC-STM) and atomic force microscopy (AFM). The in situ observation of molecular assemblies and understanding of the phase transition dynamics and ligand exchange reactions at the molecular and/or submolecular levels provide information on functional molecular design and surface engineering. In addition, ionic liquids electrochemistry is summarized from the viewpoint of single-crystal electrochemistry.

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