Tc Maximum in Solid Solution of Pyrite IrSe2-RhSe2 Induced by   Destabilization of Anion Dimers
  We have established a well-defined dome shape Tc curve in Ir0.94-xRhxSe2 superconductors. The maximum Tconset of 9.6K was obtained at x=0.36, at which the Se-Se separation in the dimer anion is the longest. Simultaneously, the destabilization of Se-Se dimers accompanied by partial elec-tron-transfer from the Ir/Rh to the chalcogenide ions result-ed in the emergence of optimal Tc. 
Jiangang Guo, Yanpeng Qi, Satoru Matsuishi, Hideo Hosono
cond-mat.supr-con cond-mat.mtrl-sci