Water adsorption on phosphorous-carbide thin films
2009 (English)In: Surface & Coatings Technology, ISSN 0257-8972, Vol. 204, no 6-7, 1035-1039 p.Article in journal (Refereed) Published
Amorphous phosphorous-carbide films have been considered as a new tribological coating material with unique electrical properties. However, such CPx films have not found practical use until now because they tend to oxidize/hydrolyze rapidly when in contact with air. Recently, we demonstrated that CPx thin films with a fullerene-like structure can be deposited by magnetron sputtering, whereby the structural incorporation of P atoms induces the formation of strongly bent and inter-linked graphene planes. Here, we compare the uptake of water in fullerene-like phosphorous-carbide (FL-CPx) thin films with that in amorphous phosphorous-carbide (a-CPx), and amorphous carbon (a-C) thin films. Films of each material were deposited on quartz crystal substrates by reactive DC magnetron sputtering to a thickness in the range 100-300 nm. The film microstructure was characterized by X-ray photoelectron spectroscopy, and high resolution transmission electron microscopy. A quartz crystal microbalance placed in a vacuum chamber was used to measure their water adsorption. Measurements indicate that FL-CPx films adsorbed less water than the a-CPx and a-C ones. To provide additional insight into the atomic structure of defects in the FL-CPx and a-CPx compounds, we performed first-principles calculations within the framework of density functional theory. Cohesive energy comparison reveals that the energy cost formation for dangling bonds in different configurations is considerably higher in FL-CPx than for the amorphous films. Thus, the modeling confirms the experimental results that dangling bonds are less likely in FL-CPx than in a-CPx and a-C films.
Place, publisher, year, edition, pages
2009. Vol. 204, no 6-7, 1035-1039 p.
Phosphorous carbide; Dangling bonds; Water adsorption; Density functional theory
Engineering and Technology
IdentifiersURN: urn:nbn:se:liu:diva-52884DOI: 10.1016/j.surfcoat.2009.06.003OAI: oai:DiVA.org:liu-52884DiVA: diva2:285773