Multiphase superconductivity

T. Ohnishi, and K. Yakushi. Multiphase superconductivity in OO-P-PV/C60 composite doped by alkali metals low-field microwave absorption and SQUID study. Physica C, 264(3-4) 161-171, June 1996. 

Thermal conductivity in the vortex phase and multiphase superconductivity in PrOs4Sbi2... 

In 1988, Cava and co-workers also prepared (88a) a quaternary oxide, Ba/K/Bi/O, and observed superconductivity at -28 K. This compound was the first "non-transition metal" oxide with a Tc above the legendary "alloy record" of 23 K. Further studies indicated (88a) that the optimum composition for "high temperature" superconductivity in this system was Ba0 6K0 4BiO3 x, having a Tc of 30.5 K (Figure 17). The samples were multiphase, and the superconducting fraction varied from 3 to 25%. Superconductivity for the rubidium-substituted compound was observed at -28.6 K. 

Superconductivity in the multiphase quaternary borocarbide system Y-Ni-B-C has been recently reported [141,142], Earlier work on valence fluctuations in ternary borides RENiaB were studied and in the case of YNi4B, a weak but reproducible signal of superconductivity at Tc of 12 K was observed. This is the first report or discovery of a ternary superconducting phase of the elements Y, Ni and B with a high Tc value (Fig. 12.27). 

This discovery generated much frenetic activity worldwide, and in early 1987 a large group at the Universities of Houston and Alabama-Huntsville reported another multiphase mixture with a superconducting transition temperature above 90 K. This was recognized as another breakthrough, as the transition temperature now exceeded 77 K,... 

Ku and Shelton (1980) characterized the crystal structure of a sample Yo.sSco 2RuB2 as LuRuB2-type, Pnma no lattice parameters were given the superconducting transition is at = 8.10-7.73 K. A ternary ScRuBj-alloy appeared to be multiphase with no LuRuB2-type phase see also Sc-Ru-B. For sample preparation, see ScOsBj. 

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