C60, as in a buckyball?  Caging 3 potassium atoms? C60 doped with potassium is known to be a superconductor below 18K [1], but that&#x27;s not &quot;high temperature&quot;.<p>[1] <a href="http:&#x2F;&#x2F;scifun.chem.wisc.edu&#x2F;chemweek&#x2F;buckball&#x2F;buckball.html" rel="nofollow">http:&#x2F;&#x2F;scifun.chem.wisc.edu&#x2F;chemweek&#x2F;buckball&#x2F;buckball.html</a>