Noelia Benito

Ag+ release inhibition from ZrCN–Ag coatings by surface agglomeration mechanism : structural characterization

New multifunctional materials based on well-established materials to which functional properties are added, such as antibacterial performance, have become a relevant research topic, in order to meet the requirements of today’s technological advances. This paper reports the results of a detailed structural and chemical characterization study of ZrCN–Ag coatings produced by reactive magnetron sputtering, as well as the release of silver after immersion in a simulated body fluid (Hank’s balanced salt solution), which mimic the material behaviour within the human body. The chemical composition was evaluated by electron probe microanalysis, x-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy, whereas the structure was assessed by Raman spectroscopy and x-ray diffraction. The material exhibits a homogeneous distribution of the elements throughout the films, with a (C + N)/Zr ratio of around 1.3 and 15 at% of silver. A mixture of amorphous (a-C and CNx) and crystalline phases (ZrCN) was identified. In addition, the silver was detected to be released in less than 0.7% of the total silver in the films, occurring during the first two hours of immersion; no further release was evidenced after this period of time. (Some figures may appear in colour only in the online journal)

Ag-Ti(C,N)-based coatings for biomedical applications : influence of silver content on the structural properties

Ag–TiCN coatings were deposited by dc reactive magnetron sputtering and their structural and morphological properties were evaluated. Compositional analysis showed the existence of Ag–TiCN coatings with different Ag/Ti atomic ratios (ranging from 0 to 1.49). The structural and morphological properties are well correlated with the evolution of Ag/Ti atomic ratio. For the samples with low Ag/Ti atomic ratio (below 0.20) the coatings crystallize in a B1-NaCl crystal structure typical of TiC0.3N0.7. The increase in Ag/Ti atomic ratio promoted the formation of Ag crystalline phases as well as amorphous CNx phases detected in both x-ray photoelectron spectroscopy and Raman spectroscopy analysis. Simultaneously to the formation of Ag crystalline phases and amorphous carbon-based phases, a decrease in TiC0.3N0.7 grain size was observed as well as the densification of coatings.

In-depth multi-technique characterization of chromium–silicon mixed oxides produced by reactive ion beam mixing of the Cr/Si interface

The great interest of mixed metal–silicon oxides lies in their suitability, among other applications, as optical coatings with an adjustable refractive index. In this paper we investigate a new method to obtain chromium and silicon mixed oxides. Using as starting point a metallic chromium film deposited on a silicon substrate by magnetron sputtering, we induce the formation of mixed oxides using reactive ion beam mixing by bombarding the Cr/Si interface with oxygen. We have varied the ion fluence (between 5 × 1016 and 1 × 1018 ions cm−2) at a fixed implantation energy of 80 keV in order to modify the final composition of the coating. The composition profiles have been obtained with Rutherford backscattering spectroscopy (RBS), by changing the He energy from 3.035 up to 3.105 MeV, and with elastic recoil detection analysis using a time of flight configuration (ERDA-ToF). Results have been compared with those obtained from secondary ion mass spectrometry (SIMS) depth profiles and Monte Carlo TRIDYN simulations. Concentration depth profiles (CDP) have been also measured using X-ray photoelectron spectroscopy (XPS) and simultaneous Ar+ bombardment, as well as angle-resolved X-ray photoelectron spectroscopy (ARXPS). All the obtained depth profiles agree remarkably well with cross-section transmission electron microscopy (TEM) observations made on the sample implanted at the highest fluence.