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2018 Fiscal Year Research-status Report

Development of new high Tc superconductors through internal and external dual-direction doping of carbon superatoms

Research Project

Project/Area Number 18K18724
Research InstitutionOsaka Prefecture University

Principal Investigator

プラシデス コスマス  大阪府立大学, 工学(系)研究科(研究院), 教授 (90719006)

Project Period (FY) 2018-06-29 – 2020-03-31
KeywordsSuperconductivity / Molecular nanocarbons / Endohedral fullerene / Dual doping / Magnetism
Outline of Annual Research Achievements

Endohedral lithium-ion encapsulated fullerene (Li+@C60) is a commercially available emerging endohedral fullerene, whose electronic properties, structures and potential applications have been recently attracting considerable interest. Following this, neutral Li@C60 has been the next intriguing target because the existence of neutral lithium metal atom inside the fullerene cage represents the creation of a “super hydrogen atom”. However, the reported preparation of neutral Li@C60 is inefficient and time consuming. We have now achieved a facile, reliable, and efficient synthesis of neutral Li@C60 by chemical reaction using an easily available reducing agent, decamethylferrocene. With solid samples produced with this method in hand, we performed X-ray, Raman, and EPR studies. We found that Li@C60 obtained by chemical reduction contains a high proportion of radical monomer species (Li+@C60(-)) due to smaller formation yield of EPR silent dimerized (Li@C60)2. We believe that not only the new synthetic procedure for production but also the properties investigation undertaken contribute greatly to the understanding of this unique family of endohedral metallofullerenes, incorporating both Li+@C60 and Li@C60. As such the results achieved in this research will be of urgent nature and broad interest to the scientific community as they are of direct relevance to materials chemists and scientists, researchers working on functional molecular materials and to the extended pi-electron based molecular carbon community.

Current Status of Research Progress
Current Status of Research Progress

1: Research has progressed more than it was originally planned.

Reason

Superconductors have no electrical resistance and carry electricity without losing energy. The development of new materials in order to achieve transition temperatures to zero-resistance as high as possible is at the extreme forefront of current challenges in materials science. C60 superconductors played leading role in materials research in the last 30 years achieving a robust zero-resistance state at record temperatures and surviving at extremely high magnetic fields. But they have reached their upper limit. Here we are facing the challenge of surpassing the past performance of C60 superconductors. We are targetting to achieve this by developing the uncharted field of high-symmetry superatomic carbon frameworks with metal ions inside the cages and using unprecedented mechanisms of electronic control by dual-direction internal and external electron doping. This is a challenging proposal because there are simply no systems of this type created before and, if and when made, theory predicts superb performance. Currently we have achieved the first milestone of producing and characterizing in the bulk the parent neutral lithium endohedral C60 fullerene - this constitutes the starting material, the synthon of our eventual targets and confirms that we are progressing at an excellent pace for this research.

Strategy for Future Research Activity

Our research plan follows two complementary procedures: (i) to develop the new synthetic chemistry needed, and (ii) to combine it with advanced structural and physical property measurements and feedback from theory. The research will include: [1] Synthesis of dual-direction-doped A+n[Li+@C60(n+1)-] phases (A = alkali metal; n = 1-6). This will define the full range of valences and electronic ground states in C60 cages dually-electron-doped internally and externally. [2] Physical control of structure and properties. Application of pressure will be used to drive insulator-to-metal transitions and trigger the emergence of superconductivity out of non-superconducting A+n[Li+@C60(n+1)-] precursors away from half filling of the conduction band. [3] Electronic and magnetic ground states in the new materials. The strong interplay between crystal and electronic structure requires the use of many advanced experimental techniques at both ambient and elevated pressures. We have the expertise to employ the full range of experimental techniques to investigate crystal structure (synchrotron X-ray & neutron diffraction), electronic structure (magnetometry, transport properties, specific heat) and dynamics (NMR/muSR/EPR & IR/Raman spectroscopy) throughout the project duration. The integrated study of structure and electronic properties in the normal and superconducting states will be the basis for theoretical understanding of the new metallic/superconducting ground states.

Causes of Carryover

The research started after the beginning of the financial year 2018 and at the beginning utilized pre-existing resources in the applicant's laboratory. Moreover, the emphasis of the project was initially (as described originally in the proposal) to isolate and purify (Li@C60)2. This was achieved by optimizing the bulk synthesis and purification of the neutral (Li@C60)2 dimer from the monomeric ionic precursor, (Li@C60)(PF6) targeting the availability of the material in large-quantities to allow full exploratory synthesis. This part of the work was successful and was achieved with resources well within our budget. The next steps involve more elaborate physical characterization as a function of temperature as well as the utilization of high pressure to enhance the properties. This will require significant resources including those carried over.

  • Research Products

    (14 results)

All 2019 2018 Other

All Int'l Joint Research (3 results) Journal Article (2 results) (of which Int'l Joint Research: 2 results,  Peer Reviewed: 2 results) Presentation (8 results) (of which Int'l Joint Research: 7 results,  Invited: 6 results) Remarks (1 results)

  • [Int'l Joint Research] University of Liverpool(英国)

    • Country Name
      UNITED KINGDOM
    • Counterpart Institution
      University of Liverpool
  • [Int'l Joint Research] Aristotle University of Thessaloniki(ギリシャ)

    • Country Name
      GREECE
    • Counterpart Institution
      Aristotle University of Thessaloniki
  • [Int'l Joint Research] Bursa Technical University(トルコ)

    • Country Name
      TURKEY
    • Counterpart Institution
      Bursa Technical University
  • [Journal Article] Structural and electronic properties of the overexpanded quaternary superconducting fulleride K0.25Rb0.25Cs2.5C602019

    • Author(s)
      Okur H. Esma、Prassides Kosmas
    • Journal Title

      Journal of Physics and Chemistry of Solids

      Volume: 131 Pages: 44~49

    • DOI

      10.1016/j.jpcs.2019.03.017

    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Reactivity of Solid Rubrene with Potassium: Competition between Intercalation and Molecular Decomposition2018

    • Author(s)
      Zhang Jiliang、Whitehead George F. S.、Manning Troy D.、Stewart David、Hiley Craig I.、Pitcher Michael J.、Jansat Susanna、Prassides Kosmas、Rosseinsky Matthew J.
    • Journal Title

      Journal of the American Chemical Society

      Volume: 140 Pages: 18162~18172

    • DOI

      10.1021/jacs.8b11231

    • Peer Reviewed / Int'l Joint Research
  • [Presentation] Quantum magnetism in fully-frustrated all-carbon π-electron systems2019

    • Author(s)
      Kosmas Prassides
    • Organizer
      The 99th Annual Meeting 2019 of Checmical Society Japan
    • Int'l Joint Research / Invited
  • [Presentation] Pressure evolution of Sm valence in (Sm1-xCax)2.75C60 fullerides2019

    • Author(s)
      Naoya Yoshikane, Kosmas Prassides
    • Organizer
      The 99th Annual Meeting 2019 of Checmical Society Japan
  • [Presentation] Carbon-based molecular materials as new electronic materials platforms2018

    • Author(s)
      Kosmas Prassides
    • Organizer
      International Workshop on New Materials and Crystal Growth
    • Int'l Joint Research / Invited
  • [Presentation] Emergent Electronic Phenomena in All-Carbon π-Electron Systems2018

    • Author(s)
      Kosmas Prassides
    • Organizer
      Gordon Research Conference (GRC), "Conductivity and Magnetism in Molecular Materials"
    • Int'l Joint Research / Invited
  • [Presentation] Towards the Assembly of Charged Analogues of Endohedral Metallofullerenes from Bowl-shaped π-Electron Molecular Units2018

    • Author(s)
      Zhanqiang Xu, Kosmas Prassides
    • Organizer
      Gordon Research Conference (GRC), "Conductivity and Magnetism in Molecular Materials"
    • Int'l Joint Research
  • [Presentation] Superconductivity and Magnetism in all-Carbon π-electron Systems2018

    • Author(s)
      Kosmas Prassides
    • Organizer
      12th International Conference on Materials and Mechanisms of Superconductivity and High Temperature Superconductors (M2S-2018)
    • Int'l Joint Research / Invited
  • [Presentation] Unconventional superconductivity and quantum magnetism in π-electron molecular systems2018

    • Author(s)
      Kosmas Prassides
    • Organizer
      2018 European Materials Research Society (E-MRS) Fall meeting
    • Int'l Joint Research / Invited
  • [Presentation] Emergent Electronic Phenomena in All-Carbon π-Electron Molecular Systems2018

    • Author(s)
      Kosmas Prassides
    • Organizer
      The 8th TOYOTA RIKEN International Workshop on Organic Semiconductors
    • Int'l Joint Research / Invited
  • [Remarks] Electronic Functional Materials Laboratory

    • URL

      http://mtr1.osakafu-u.ac.jp/prassides-lab/

URL: 

Published: 2019-12-27  

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