Chevrel phases
Chevrel phases are chemical compounds of molybdenum with the general form M x Mo 6 Y 8 . Various elements such as calcium , strontium , barium , tin (II), lead (II), gold or lanthanoids are possible as metal M. The counterion Y is always a chalcogenide , either sulfur , selenium or tellurium .
In Chevrel phases, there are isolated molybdenum octahedra, which are surrounded by the chalcogenide atoms. The Mo-Mo bond distances between the individual clusters are 327 pm, within 267–274 pm (each for PbMo 6 S 8 )
The best known Chevrel phase is PbMo 6 S 8 . It is superconducting and has a high critical field strength . The transition temperature is 15 Kelvin with a critical field strength of 60 Tesla .
literature
Erwin Riedel: Modern inorganic chemistry . de Gruyter, Berlin 1999, ISBN 3-11-015672-5