Detection of a Pd–Ni interlayer at the Pd/Ni interface of an epitaxial Pd film on cube textured nickel ()

We studied the microstructure of a Pd overlayer deposited on a cube textured Ni(0 0 1) substrate using synchrotron X-ray scattering. We find the existence of an epitaxial Pd–Ni interlayer between the epitaxial Pd layer and the Ni substrate. The Pd–Ni interlayer, which is compressively strained in a manner similar to the Pd overlayer, seemingly acts to relieve the strain at the Pd/Ni interface caused by the Pd–Ni lattice mismatch. The Ni mosaic distribution of our samples is multiply spiked with a rocking angle spread of ∼16°, which reconciles the previously reported observation of saw tooth peaks on top of a Gaussian distribution for a similarly prepared Pd on Ni specimen. The observed sharpening of the mosaic distributions for the Pd(0 0 2) grains (full-width at half-maximum (FWHM)=1.95°) and for the (0 0 2) grains of Pd–Ni interlayer (FWHM=3.0°) indicates that the Pd and Pd–Ni(0 0 2) layers conform to the surface morphology instead of to the (0 0 1) crystallographic planes of Ni-substrate grains.