Sputtering, physical alloys

R. Behrisch, ed., "Sputtering by Particle Bombardment II Sputtering of Alloys and Compound, Electron and Neutron Sputtering, Surface Topography," in Topics in Applied Physics, Vol. 52, Springer-Vedag, Berlin, 1983. 

When Y 1, (12.26) reduces to NA/NB = r, which is the same result as inert-gas ion sputtering of alloy AB. On a physical basis, this is because, with high sputtering yield Y, very few of the implanted atoms are retained in the material. 

Synthesis of metallic nanoparticles proceeds in many ways they can be divided into physical and chemical. Physical methods include inert gas condensation, arc discharge, ion sputtering, and laser ablation. The main idea behind these methods is condensation of solid particles from the gas phase, the substrate for nanoparticle generation being pure metals (or their mixtures/alloys in the case of complex particle composition). Chemical methods, in turn, include various methods utilizing... 

Physical vapor deposition (PVD). This class of deposition refers to evaporation and sputtering processes performed in vacuum chambers. The material of interest comes from a solid source that is either heated (evaporation) or etched using plasma (sputtering) yielding a vapor that condenses on the substrate to form the electrode. Multiple sources can be used at once to form alloys. PVD processes usually lead to polycrystalhne films. 

Many studies carried out with bimetallic materials show that Pt-Ru is today one of the best options to oxidize methanol. Thus, a simple way to prepare active Pt-Ru catalysts involves the deposition of metallic nanoparticles from a suspention onto the carbon microparticles by the method known as formic acid method [24]. Considering that the crystal structures of Pt and Ru are different, Pt being fee and Ru hep, the final crystal structure of the alloy depends on the composition. For Ru atomic fractions up to 0.6-0.7, the two metals form solid solutions in which Ru atoms replace Pt lattice points in the fee structure. The opposite situation, Pt atoms replacing Ru atoms in the hep structure is found for Ru atomic fractions higher than about 0.7. However, the crystal structure seems to depend also on the physical state of the material. When nanoparticles are prepared by reduction of ionic metal species, there is at least one report [25] claiming that the fee stmeture prevails up to 80 at.%Ru. On the other hand in sputtered films the hep structure is predominant even at low Ru fractions [26]. 

Physical vapor deposition (PVD) is a technique for making thin films at low temperatures and is widely used in planar technology in electronics. It consists of evaporating or sputtering a solid, such as a metal, an alloy, or a mixture of solids, in a vacuum and condensing the compound on the substrate to be covered. In certain variations the vapor is reacted with gases introduced in the vacuum. That variation is reactive evaporation or reactive sputtering. The product can be a polycrystalline deposit or a powder. 

Significant progress has been made over the last decade in the manufacturing of thin membranes. The thickness of the thinnest laminated membranes which are commercially available is usually limited to 15 pm. Thinner membranes (1 pm < 5 < 10 pm) can be obtained by sputtering palladium or its alloys over adequate substrates (physical vapor... 

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