Initial stages of ion-induced interfacial mixing in the Ag-Pd system

Structural and electronic properties ofAg−Pdsuperlattices

“…As stated in the introduction, other studies found interdiffusion to be negligible below 200°C. 13,16,[18][19][20][21] However, this also implies that the heterostructures are not uniform across the whole surface and/or across the whole depth. In order to observe several peaks, part of the heterostructure must have a slightly different sequence of layers, but still be uniform and crystalline enough to give a diffraction peak.…”

“…[7][8][9][10] Heterostructures built from alternating layers of deposited Ag and Pd have been studied experimentally in the past few years using x-ray diffraction (XRD), synchrotron-radiation induced photoelectron spectroscopy (SR-PES), atomic force microscopy, scanning tunneling microscopy (STM) and many other techniques. [11][12][13][14][15][16][17][18][19][20][21] At room temperature Ag and Pd have been described as growing layer by layer on each other. Standard properties are still controversial, as both metals have been observed to grow on the other with their own lattice parameter as well as pseudo-morphically.…”

“…14,15,22 In superlattices, root-mean-squared interface roughness can be lowered to about 1 atomic layer 21 but interdiffusion occurs above 200°C. 13,16,[18][19][20][21] Much is known about thick multilayers of Ag and Pd, about the epitaxial growth of the metals on each other, and about their interdiffusion and alloy formation. The Ag/ Pd system looks like the ideal superlattice: perfectly layered when grown at room temperature and without any interdiffusion.…”

Demixing processes in AgPd superlattices

“…The AgPd system is one of the most studied alloy systems, showing very different phases, either in the bulk and in thin films at equilibrium, or in epitaxial Ag-Pd multilayers: in the bulk, Ag and Pd are fully miscible and form ordered phases over the whole composition range [6], while an Ag concentration close to 90% is often reported at the surface of AgPd alloys [7][8][9][10] and demixing in AgPd thin films grown on Ru is observed upon annealing [5]. Strikingly, while Ag and Pd seem to present a strong tendency to order at equilibrium, Ag-Pd superlattices grown at room temperature show sharp interfaces [11][12][13][14].…”

“…Strikingly, while Ag and Pd seem to present a strong tendency to order at equilibrium, Ag-Pd superlattices grown at room temperature show sharp interfaces [11,12,13,14].…”