I'm trying to understand a bit more about high temperature superconductors. I'm familiar with BCS theory and a little bit about high temp superconductors, but I'm still confused about a bunch of stuff Why exactly is copper oxide used in high temperature superconductors? Why is this specific compound of copper used? What properties does it have that makes it so special? If we took a step down the periodic table to silver would it all of a sudden set high temp superconductors back to only working at 30K instead of the 130K copper oxide affords us? I know the valence electrons in both molecules are the same, but there are other factors that come into play lower down the periodic table. The only real reason I can think of right now is because it's cheap. If anyone could shed some light on this (and tell me where I'm wrong in any of the statements I've already made) it would be great Edit: Had a couple questions answered already, my only real question now is could anyone tell me the relationship between the substance used and the temperature required for superconductivitiy?