Spelling suggestions: "subject:"high/maximumentropy alloys"" "subject:"high/measuredentropy alloys""
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Characteristics of microstructure and mechanical properties in body centered-cubic refractory high/medium entropy alloys / BCC耐熱高・中エントロピー合金が示す組織と力学特性の特徴QIAN, HE 23 March 2022 (has links)
京都大学 / 新制・課程博士 / 博士(工学) / 甲第23891号 / 工博第4978号 / 新制||工||1777(附属図書館) / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 辻 伸泰, 教授 乾 晴行, 教授 安田 秀幸 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM
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Deformation mechanisms of the equiatomic Cr-Co-Ni medium-entropy alloy / 等原子量Cr-Co-Niミディアムエントロピ-合金の塑性変形機構LI, Le 26 September 2022 (has links)
京都大学 / 新制・課程博士 / 博士(工学) / 甲第24231号 / 工博第5059号 / 新制||工||1790(附属図書館) / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 乾 晴行, 教授 田中 功, 教授 安田 秀幸 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM
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Deformation Mechanisms of Single Crystals of FCC Medium Entropy Alloys / 面心立方構造を有する中エントロピー合金単結晶の塑性変形機構Ashif, Equbal 24 September 2021 (has links)
京都大学 / 新制・課程博士 / 博士(工学) / 甲第23508号 / 工博第4920号 / 新制||工||1768(附属図書館) / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 乾 晴行, 教授 安田 秀幸, 教授 辻 伸泰 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM
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Computational Design of Compositionally Complex 3D and 2D SemiconductorsJanuary 2020 (has links)
abstract: The structural and electronic properties of compositionally complex semiconductors have long been of both theoretical interest and engineering importance. As a new class of materials with an intrinsic compositional complexity, medium entropy alloys (MEAs) are immensely studied mainly for their excellent mechanical properties. The electronic properties of MEAs, however, are less well investigated. In this thesis, various properties such as electronic, spin, and thermal properties of two three-dimensional (3D) and two two-dimensional (2D) compositionally complex semiconductors are demonstrated to have promising various applications in photovoltaic, thermoelectric, and spin quantum bits (qubits).3D semiconducting Si-Ge-Sn and C3BN alloys is firstly introduced. Density functional theory (DFT) calculations and Monte Carlo simulations show that the Si1/3Ge1/3Sn1/3 MEA exhibits a large local distortion effect yet no chemical short-range order. Single vacancies in this MEA can be stabilized by bond reformations while the alloy retains semiconducting. DFT and molecular dynamics calculations predict that increasing the compositional disorder in SiyGeySnx MEAs enhances their electrical conductivity while weakens the thermal conductivity at room temperature, making the SiyGeySnx MEAs promising functional materials for thermoelectric devices. Furthermore, the nitrogen-vacancy (NV) center analog in C3BN (NV-C3BN) is studied to explore its applications in quantum computers. This analog possesses similar properties to the NV center in diamond such as a highly localized spin density and strong hyperfine interactions, making C3BN suitable for hosting spin qubits. The analog also displays two zero-phonon-line energies corresponding to wavelengths close to the ideal telecommunication band width, useful for quantum communications.
2D semiconducting transition metal chalcogenides (TMCs) and PtPN are also investigated. The quaternary compositionally complex TMCs show tunable properties such as in-plane lattice constants, band gaps, and band alignment, using a high through-put workflow from DFT calculations in conjunction with the virtual crystal approximation. A novel 2D semiconductor PtPN of direct bandgap is also predicted, based on pentagonal tessellation.
The work in the thesis offers guidance to the experimental realization of these novel semiconductors, which serve as valuable prototypes of other compositionally complex systems from other elements. / Dissertation/Thesis / Doctoral Dissertation Materials Science and Engineering 2020
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