The effect of solution pH on the misfit of thin electrodeposits of nickel on single-crystal copper substrates

Abstract

Nickel was electrodeposited onto thin (001) single-crystal copper substrates. Deposit thicknesses were in the range 10–500 Å. The misfit, determined by electron diffraction, was measured as a function of thickness for deposits prepared from electrolytes with pH values of 2·4, 3·3 and 5·7. At any given thickness the measured misfit increased with decreasing pH. Transmission electron microscopy confirmed that the epitaxial deposits were initially in a state of relatively high tensile strain. Misfit dislocations were generated to relieve the strain. The relatively high residual strain in deposits plated from high pH solutions, as compared to those plated from low pH solution, is explained in terms of the extent to which codeposited foreign substances prevented dislocation glide.