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論文 / 著書情報 Article / Book Information 論文 / 著書情報 Article / Book Information 題目(和文) Title(English) Exploration of new iron pnictide superconductors utilizing high pressure synthesis 著者(和文) 村場善行 Author(English) Yoshinori Muraba 出典(和文) 学位:博士(工学), 学位授与機関:東京工業大学, 報告番号:甲第9505号, 授与年月日:2014年3月26日, 学位の種別:課程博士, 審査員:細野 秀雄,阿藤 敏行,須崎 友文,平松 秀典,松石 聡 Citation(English) Degree:Doctor (Engineering), Conferring organization: Tokyo Institute of Technology, Report number:甲第9505号, Conferred date:2014/3/26, Degree Type:Course doctor, Examiner:,,,, 学位種別(和文) 博士論文 Type(English) Doctoral Thesis Powered by T2R2 (Tokyo Institute Research Repository) Exploration of new iron pnictide superconductors utilizing high pressure synthesis Yoshinori Muraba Department of Materials Science and Engineering Interdisciplinary Graduate School of Science and Engineering Tokyo Institute of Technology 2014 Contents Chapter 1 1 General introduction 1.1. Background of present study.........................…...................................................................1 1.1.1. Histroy of superconductor....................................................................................................1 1.1.2. Crystal structures of iron-based superconductors...............................................................3 1.1.3. Superconductivity induced by various doping modes..........................................................4 1.1.4. Generic phase diagrams......................................................................................................6 1.1.5. Electronic structures............................................................................................................7 1.1.6. Comparison between Fe-based and Cu-based Superconductivity.......................................8 1.1.7. Relation between structure in FeAs layer and superconducting temperature...................10 1.2. Objectives and outline ........................................................................................................14 References...................................................................................................................................18 Figures and Tables.....................................................................................................................27 Chapter 2 35 High-pressure synthesis of the indirectly electron-doped 122 iron superconductor Sr1−xLaxFe2As2 with a maximum Tc = 22 K 2.1. Introduction ........................................................................................................................35 2.2. Experimental procedures ...................................................................................................36 2.3. Results and discussion.........................................................................................................36 2.3.1. XRD and Rietveld refinement.............................................................................................37 2.3.2. Electron transport property................................................................................................39 2.3.3. Electron phase diagram.....................................................................................................41 2.4. Summary..............................................................................................................................43 References...................................................................................................................................44 Figures.........................................................................................................................................46 Chapter 3 52 Hydrogen in layered iron arsenides: Indirect electron doping to induce superconductivity 3.1. Introduction.........................................................................................................................52 3.2. Experimental procedures....................................................................................................53 3.3. Results and discussion.........................................................................................................56 3.3.1. XRD and Rietveld refinement........................................................................................... 56 3.3.2. TG-MS measurement........................................................................................................ 56 3.3.3. NPD and Rietveld refinement............................................................................................57 3.3.4. Electric, magnetic and thermodynamic properties............................................................57 3.3.5. Electronic structure calculation.........................................................................................58 3.3.6. CaFeAsH1-xFx......................................................................................................................60 3.4. Summary..............................................................................................................................61 References...................................................................................................................................62 Figures.........................................................................................................................................65 Chapter 4 75 Enhancing the three-dimensional electronic structure in 1111-type iron arsenide superconductors by H-substitution 4.1. Introduction.........................................................................................................................75 4.2. Experimental procedures...................................................................................................76 4.3. Results..................................................................................................................................78 4.3.1. Crystal structure................................................................................................................ 78 4.3.2. Superconducting Properties.............................................................................................. 79 4.3.3. Electronic structures..........................................................................................................80 4.4. Disucussion...........................................................................................................................81 4.5. Summary..............................................................................................................................84 References...................................................................................................................................86 Figures.........................................................................................................................................88 Chapter 5 96 La-substituted CaFeAsH superconductor with Tc = 47 K 5.1. Introduction.........................................................................................................................96 5.2. Experimental procedures....................................................................................................96 5.3. Results and discussion.......................................................................................................98 5.3.1. XRD and Rietveld refinement...........................................................................................98 5.3.2. Elemental analysis..............................................................................................................99 5.3.3. Electron transport property..............................................................................................100 5.3.4. Electron phase diagram...................................................................................................101 5.4. Summary............................................................................................................................104 References.................................................................................................................................105 Figures.......................................................................................................................................108 Chapter 6 112 General conclusions Acknowledgements..........................................................................................................117 Publication list...................................................................................................................120 Presentation list.................................................................................................................122 Chapter 1 General Introduction 1.1 Back ground of study 1.1.1 Histroy of superconductor Figure 1-1 shows the history of representative superconductors and the development of the superconducting temperatures (Tc). Superconductivity was firstly discovered by Kamerlingh Onnes in 1911,1 which was achieved in elemental Hg at ~4.2 K by the observation of the zero resistance. Then, he also demonstrated that many simple elements, such as Sn, Pb and so on exhibit superconductivity below 10 K.2 Today, it has been confirmed that more than 30 species of simple elements show the superconductors at ambient pressure. In addition, many 3-6 intermetallic compounds, especially containing Nb, exhibit comparatively high Tc. The Tc gradually increased with further studies of intermetallic compounds and reached to ~25 K in 6 Nb3Ge in 1973. Their superconductive properties
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