Ordered CoSn-type ternary phases in Co3Sn3-xGex

CoSn is the prototype compound of the B35 structure, which has long been of interest due to its rarity and unusually low packing density. We report the synthesis and properties of the solid solution Co3Sn3-xGex for 0 <= x <= 2, in order to clarify the conditions necessary to stabilize such a phase. By taking advantage of the chemical differences between the two crystallographically inequivalent Sn sites in the structure, we observe ordered ternary phases, nominally Co3SnGe2 and Co3Sn2Ge. The electron count and unit cell configuration remain unchanged from CoSn; these observations thus help to clarify some ambiguities about the stabilizing forces in this crystal structure. All compounds are normal metals with room temperature conductivities ranging from 5 to 50 mu Omega cm and are weakly paramagnetic. (C) 2012 Elsevier B.V. All rights reserved.