INOR 1032 |
| Values of 'Weighted Harmonic Mean Electronegativity (WHME)'for the best-ranked copper-oxide-based high-Tc superconductors were observed to be concentrated in a narrow range between 4.7 to 4.9 [eV] creating a peak in a figure for Tc versus WHME [1]. The definition of WHME is χWH=n[∑(ωi/χi)]-1where n=∑ωi. After 17 years, inclusion of data for more recently discovered superconductors shows that the same trend still holds and also that the low-Tc superconductors and non-superconductors are essentially outside this critical range. What is interesting is that this range is close to the work function of copper metal. Therefore, it seems that the copper oxide structure with the necessary additional elements together creates in harmony a kind of metallic character. Copper metal itself is not superconductive, but it seems that the work function of the copper-oxide-based structure needs to be at the same level as that for the metal copper. This point will be discussed. In designing superconductors, the WHME approach is convenient as a systematic guideline so that one can narrow down the choice of elements to add next for a possible improvement. Also, C60-based superconductors are showing a trend indicating where it is heading. The WHME approach appears to be effective for both inorganic and organic superconductive materials. Reference:[1] S.Ichikawa, J.Phys.Chem., 93, 7302 (1989). |
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General
1:30 PM-4:10 PM, Thursday, 14 September 2006 Moscone Center -- Room 304, Oral
Division of Inorganic Chemistry |