AN ELECTRON DIFFRACTION STUDY OF SOLIDIFIED MIXTURES OF ARGON AND KRYPTON AND OF ARGON AND NEON

Gaseous mixtures of argon with krypton, and of argon with neon, were condensed on to substrates held at 7°K inside an electron diffraction camera. Diffraction studies of the deposits so formed were subsequently carried out with 50 kv electrons. The argon-krypton mixture crystallized into a single face-centred cubic phase whose lattice parameter depended in a non-linear manner on the atomic concentration of argon in the mixture and was intermediate between the lattice parameters of the two pure components. The argon-neon mixture crystallized into two separate phases, one consisting of crystals of pure neon, the other being very disordered and probably consisting principally of argon. These results are discussed with reference to a theoretical model of binary mixtures proposed by Prigogine and by Scott.