# 4 element super conductor without oxygen and iron

I am trying to find a list with super conductors. In particular I am searching for a superconductor, that consists of 4 elements none of which is Oxygen.

The reason I rejected Oxygen, is because(from the kinematic factor) the maximum energy from scattering with the Oxygen is about $730 keV$.

Therefore-unfortunately-I have to reject YBCO superconductors.

In particular I have to analyse an RBS spectrum of a supposed 4-element well known super conductor.

I can't find any 4-element-superconductor without oxygen. Is there anyone, or it might be the case where the sample is bad described?

Just for reference the RBS spectrum is

EDIT

I also tested iron based superconductors, but it seems that I need a heavier element. For instance a superconductor containing $Ba, K, Fe, As$ has the following RBS spectrum

The analysis indicates that the superconductors consists of 4 elements which are

• Bi(28.5%)
• Sr(28.4%)
• Cu(28.2%)
• K(14.8%)

Does a superconductor like that really exists? I mean OK about Bismuth or Copper or even Strontium...How about Potassium? The combination of those doesn't seem right to me...

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A very cursory search found Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$. I guess looking at the Pnictides in general could be good bet –  Lagerbaer Nov 29 '13 at 15:59
@Lagerbaer: Thank you very much for your comment! I've used your superconductor, but it appears that iron-based are not suitable... It must be a heavier element... –  Thanos Nov 30 '13 at 10:13