| Project/Area Number |
63060004
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| Research Category |
Grant-in-Aid for Specially Promoted Research
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| Allocation Type | Single-year Grants |
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| Research Institution | TOKYO METROPOLITAN UNIVERSITY |
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Principal Investigator |
IKEMOTO Isao Tokyo Metropolitan University,Chemistry,Professor, 理学部, 教授 (00011601)
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| Co-Investigator(Kenkyū-buntansha) |
SAITO Gunji Kyoto University,Chemistry,Professor, 理学部, 教授 (40132724)
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| Project Period (FY) |
1988 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥254,000,000 (Direct Cost: ¥254,000,000)
Fiscal Year 1992: ¥20,000,000 (Direct Cost: ¥20,000,000)
Fiscal Year 1991: ¥40,000,000 (Direct Cost: ¥40,000,000)
Fiscal Year 1990: ¥40,000,000 (Direct Cost: ¥40,000,000)
Fiscal Year 1989: ¥69,000,000 (Direct Cost: ¥69,000,000)
Fiscal Year 1988: ¥85,000,000 (Direct Cost: ¥85,000,000)
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| Keywords | Organic Superconductors / radical salt / BEDT-TTF / DMET / unsymmetrical electron donor / conductivity / isotope effect / fullerene / BEDTーTTF / 相転移 / 相移転 |
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| Research Abstract |
1)To develop new superconductors,we investigated mainly on the derivative molecules of an unsymmetrical donor DMET;DMPT,DMMT,DIMET and ETDM.DMPT and DMMT are the derivatives with different side-bones from DMET,and DIMET and ETDM have the same backbone to that of DMET,but a different arrangement of hetero-atoms from that of DMET.Several radical salts of DIMET and ETDM show a metallic behavior at low temperature,so there remains the possibilities that the superconductors based on DIMET or ETDM will be discovered.
2)The fullerene superconductors are also studied. C_<60>M_3 was found to have a transition from metallic phase to a superconducting phase. The doping method with metal azide produced the material (C_<60>K_2Cs_1) which had 100% superconducting volume,so this method was clarified to be efficient for making a good fullerene superconductor. We obtained more reliable coherent lengths for C_<60> superconductors by the aid of the renormalization theory.
3)In the case of BEDT-TTF salts,we
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discovered five superconductors; kappa-(BEDT-TTF)_2Cu(NCS)_2(Tc=10.4K), kappa'-(BEDT-TTF)_2Cu_2(CN)_3(Tc=3.8K), kappa-(BEDT-TTF)_2Cu(CN)[N(CN)_2](Tc=11.2K), alpha-(BEDT-TTF)_2NH_4(SCN)_4(Tc=0.8K), alpha-(BEDT-TTF)_2KHg(SCN)_4(Tc=0.1-0.2K). In addition, we observed a new superconducting phase (Tc=2k) in beta(BEDT-TTF)_2I_3. In these salts we studied the isotropic effect on Tc, substituting the CH_2 groups of the donor molecules by ^<13>CH_2 and by CD_2. The deuterated salt of kappa-(BEDT-TTF)_2Cu(CN)[N(CN)_2] recorded the highest Tc(12.3K)among the ambient pressure TTF-based organic superconductors.In the process of this investigation we proposed a molecular and crystal designing for superconductor.Namely,"big and thin anion which forms two-dimensional anion layer gives the high Tc salts."We have also derived a new molecular and crystal design by finding the structural correlations between the opening of the anion layer and the donor packing pattern and the one between Tc and the conduction volume of the donor layer.Employing not only BEDT-TTF but also newly prepared donor molecules,we have obtained the new superconductors and a number of metallic salts down to liquid He temperature.Further research for the high Tc organic superconductors is currently under way. Less
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