Investigation of relaxation processes in nonequilibrium states of quench-condensed copper films with hydrogen Impurities at temperatures below 5 K

Relaxation processes in the nonequilibrium state of quench-condensed polycrystalline films of copper with hydrogen impurities are investigated. Films of thickness 50–250 Å were condensed under hydrogen pressures PH2=3.10−6−1.10−4 Torr on a substrate cooled by liquid helium to temperatures 1.4−2.5 K. The resistivity of the films was measured in situ, and electron diffraction patterns were recorded. The films exhibited high (nonequilibrium) values of hydrogen concentration (up to ∼30 at.%) and were in the labile state. It is shown that a transition of the films to a more equilibrium state is accompanied by a considerable displacement of hydrogen impurities at temperatures ≤5 K. The corresponding structural relaxation in the films is exhibited in the form of alternating increase and decrease in the crystallite lattice parameters, accompanied by large nonuniform deformation of the crystallites. The nature of observed relaxation processes in the nonequilibrium state bears the features of spinodal decomposition. The effect of two-dimensional nature and inhomogeneous (granular) structure on the mode of decomposition of inhomogeneous state of the films is considered.

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