For 10 points, name these devices that lack electrical resistance.
One type of these devices includes perovskites. An alloy of lead and bismuth was not recognized as one of these until the discovery of the Meissner Effect. Cooper pairs are involved the BCS Theory that describes how another type of these devices work. Those (*) Type I devices exhibit perfect diamagnetism, and can only work below a low critical temperature. For 10 points, name these devices that lack electrical resistance.
One type of these devices includes perovskites. An alloy of lead and bismuth was not recognized as one of these until the discovery of the Meissner Effect.
{superconductors} [prompt on {superconductivity}]