Water adsorption on phosphorous-carbide thin films

E. BROITMAN , A. FURLAN , G.K. GUEORGUIEV, ZS. CZIGÁNY, A.M. TARDITI, A.J. GELLMAN, S. STAFSTRÖM, L. HULTMAN

SURFACE AND COATINGS TECHNOLOGY

ELSEVIER SCIENCE SA

Año: 2009 vol. 204 p. 1035 - 1039

0257-8972

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 tent to oxidize/hydrolize rapidly when in contact with air. recently, we demostrated that CPx thin films with a fulleren-like structure can be deposited by magnetron sputtering, whreby the structural incorporation of P atoms induces the formation of strongly bent and inter-linked graphene planes. Here, we compare the update of water in fullerene-like phosphorous carbide (FL-CPx) thin films with that in amorphous phosphorous carbide (a-CPx), and amorphous carbide (a-C) thin films. Films of each material were deposited on quartz crystal sustrates by reactive DC magnetron sputtering to a thickness in the range 100-300 nm. The film microstucture was characterized by X-ray photoelectron spectroscopy, and high resolution transmission electron spectroscopy. A quartz crystal microbalance placed in vacuum chamber was used to measure their water adsorption. measurements indicated 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 frame work of density functional theory. Cohesive energy comparition reveals that the energy cost formation for dangling bonds in differents configutations is considerably higher in FL-CPx than for amorphous films. Thus, the model confirms the experimentals results that dangling bonds are less in FL-CPx than in a-CPx and a-C films.