title: The influence of hydrogen contamination on the structural stability of CoSn under compression.
abstract: The binary CoSn compound has a unique ground state large-void crystal structure, whose stability under pressure has recently been examined. Whereas theoretical results predicted a series of phase transformations, the room temperature experiments did not observe any structural change. We suggest that the large void of a CoSn-type structure could contain natural impurities such as hydrogen, which can influence the thermodynamic stability of a CoSn system and explain the unusual disagreement between the theoretical and experimental results. Based on first-principles calculations we reveal that the contamination of CoSn by hydrogen only results in a subtle change of structural parameters and the equation of state of CoSn, but drastically increases the stability of the CoSn-type phase in comparison with the high-pressure phases predicted earlier. We argue that the hardly detectable natural impurities of light elements in porous compounds like CoSn are able to change the phase equilibria.
authors.affiliation: Theory and Modeling Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping S-581 83, Sweden.
authors.forename: A S
authors.initials: AS
authors.lastname: Mikhaylushkin
mesh_terms: D003035:Cobalt / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D008968:Molecular Conformation; D056004:Molecular Dynamics Simulation; D017971:Tin Compounds / Q000737:chemistry*
chemical_list: D017971:Tin Compounds; D003035:Cobalt; D006859:Hydrogen