Objectives: Using dental Ti implants has become a well-accepted and used method for replacing missing dentition. It has become evident that in many cases peri-implant inflammation develops. The objective was to create and evaluate the antibacterial effect of silver nanoparticle (Ag-NP) coated Ti surfaces that can help to prevent such processes if applied on the surface of dental implants. Methods: Annealing I, Ag ion implantation by the beam of an Electron Cyclotron Resonance Ion Source (ECRIS), Ag Physical Vapor Deposition (PVD), Annealing II procedures were used, respectively, to create a safely anchored Ag-NP layer on 1x1 cm 2 Grade 2 titanium samples. The antibacterial effect was evaluated by culturing Staphylococcus aureus (ATCC 29213) on the surfaces of the samples for 8 hours, and comparing the results to that of glass as control and of pure titanium samples. Alamar Blue assay was carried out to check cytotoxicity. Results: It was proved that silver nanoparticles were present on the treated surfaces. The average diameter of the particles was 58 nm, with a 25 nm deviation and Gaussian distribution, the the filling factor was 25%. Antibacterial evaluation revealed that the nanoparticle covered samples had an antibacterial effect of 64.6% that was statistically significant. Tests also proved that the nanoparticles are safely anchored to the titanium surface and are not cytotoxic. Conclusion: Creating a silver nanoparticle layer can be an option to add antibacterial features to the implant surface and to help in the prevention of peri-implant inflammatory processes. Recent studies demonstrated that silver nanoparticles can induce pathology in mammal cells, thus safe fixation of the particles is essential to prevent them from getting into the circulation.

In this work, the performance of gold nanoislands was investigated for Localized Surface Plasmon Resonance (LSPR) and Surface Enhanced Raman Spectroscopy (SERS) applications. Nanoislands were generated by thermally annealing thin layers of gold (having thickness in the 6-12 nm range), which was previously deposited by vacuum thermal evaporation onto glass substrates. Gold nanoparticles (AuNP) were evaluated based on their plasmonic and SERS performance and morphological properties. Scanning Electron Microscopy (SEM) was used to measure the average particle size and average interparticle distance in order to correlate them with the obtained plasmonic/Raman capabilities. The technological parameters of nanoisland fabrication for optimal performances were also determined.

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It has been shown by the Auger depth profiling technique that the concentration profile at the initially sharp Si/Ge interface in amorphous Si/Ge multilayers shifted but remained still sharp after a heat treatment at 680 K for 100 h. At the same time the fast diffusion of Si resulted in the formation of an almost homogeneous Ge͑Si͒ amorphous solid solution, while there was practically no diffusion of Ge into the Si layer. This is direct evidence on the strong concentration dependence of the interdiffusion coefficient in amorphous Si/Ge system, and it is in accordance with the previous indirect result obtained from the measurements of the decay of the small angle Bragg peaks, as well as with finite difference simulations. © 2001 American Institute of Physics. ͓DOI: 10.1063/1.1331330͔Changes in atomic structures of amorphous semiconductors and their relationships to physical properties are currently of interest due to their useful optical and electronic features.1,2 Since most structural changes are related to atomic diffusion, any real understanding of the structural transformation, homogenization, etc., must be based on the knowledge of the diffusion processes. The study of diffusion in amorphous materials includes some difficulties. One of the main problems is related to the thermal stability of the amorphous phase; the diffusional measurements should be carried out at low temperatures for very short diffusion times in order to avoid structural changes due, e.g., to structural relaxation. Additionally, in amorphous semiconductors the mechanism of diffusion is also not fully understood.3-5 Thus, for example factors controlling the details of diffusional homogenization in amorphous Si/Ge multilayers are still under discussion. First of all the diffusional asymmetry ͑manifested in the strong concentration dependence of the interdiffusion coefficients͒, 6 the significant pore formation during the diffusional mixing, 7 and the possible role of diffusional stresses 8 are the most important factors indicating the need of a better understanding of the previous process.In this article interdiffusion in amorphous Si-Ge multilayered specimens is studied by Auger depth profiling. The primary objective of the present investigation is to observe the predicted asymmetric change of composition caused by the strong concentration dependence of the diffusion coefficients. Experimental results, obtained from small angle x-ray diffraction ͑SAXRD͒ measurements at different average compositions indicated a strong concentration dependence of the chemical diffusion parameters.9,10 Although such a strong concentration dependence inevitably should lead to a significant curvature on the ln(I/I 0 ) ͑I/I 0 is the normalized height of the first order SAXRD peak͒ versus time plots 11 ͑and to oscillatory behavior of the higher order peaks͒, later on the experimentally observed curvature was rather attributed by the same group to the effects of structural relaxation and coupling back effects of stresses of diffusional origin were also excluded....

Multilayers of hydrogenated ultrathin (3 nm) amorphous a-Si and a-Ge layers prepared by sputtering have been studied by atomic force microscopy (AFM) and transmission electron microscopy (TEM) to check the influence of annealing on their structural stability. The annealed multilayers exhibit surface and bulk degradation with formation of bumps and craters whose density and size increase with increasing hydrogen content and/or annealing temperature and time. Bumps are due to the formation of H2 bubbles in the multilayer. The craters are bumps blown up very likely because of too high a gas pressure inside. The release of H from its bonds to Si and Ge occurs within cavities very likely present in the samples. The necessary energy is supplied by the heat treatment and by the recombination of thermally generated carriers. Results by energy filtered TEM on the interdiffusion of Si and Ge upon annealing are also presented

a b s t r a c t Composition depth profiles of d.c.-plated and pulse-plated Fe-Ni alloys have been investigated with the reverse depth profile analysis method. When d.c. plating is applied, the mole fraction of iron near the substrate is higher than during steady-state deposition since iron is preferentially deposited beside nickel and the achievement of the steady-state deposition condition takes time. The steady-state composition was achieved typically after depositing a 90-nm-thick alloy layer. In the pulse-plating mode, samples with nearly uniform composition could be obtained at a duty cycle of 0.2 or smaller, and a continuous change in the composition profile could be seen as a function of the duty cycle above this value. A constant sample composition was achieved with pulse-plating in a wide peak current density interval. The composition depth profile was also measured for a wide range of Fe 2+ concentration. The different characteristics of the composition depth profile as a function of the deposition mode can be explained mostly in terms of mass transport effects. The elucidation of the results is fully in accord with the kinetic models of anomalous codeposition and with the assumption of the superposition of a stationary and a pulsating diffusion layer. The results achieved help to identify the conditions for the deposition of ultrathin magnetic samples with uniform composition along the growth direction.

It is shown that the well-known blue-shift of the fundamental absorption edge in as-deposited compositionally modulated amorphous Si/Ge and As 6 Se 94 /Se 80 Te 20 multilayers (with periods of 4-8 nm) is further enhanced due to the thermal or laser-induced intermixing of adjacent layers.The laser-induced intermixing process, as supported by experiments and model calculations, can be attributed to both the local heating and photo-effects in As 6 Se 94 /Se 80 Te 20 multilayers, while only the thermal effects were observed for Si/Ge multilayers. Structural transformations, based on this enhanced interdiffusion, provides good capability for spatially patterning optoelectronic devices and digital information recording. a) Corresponding author.

In order to explore the possible surfactant effect of Ag on the formation of electrodeposited multilayers, Co/Cu(Ag) multilayers were prepared by this technique and their structure and giant magnetoresistance (GMR) were investigated. The multilayers were deposited from a perchlorate bath with various amounts of Ag + ions in the solution for incorporating Ag atoms into the multilayer stack. Without Ag addition, secondary neutral mass spectroscopy (SNMS) indicated a well-defined composition modulation of the undermost Co/Cu bilayers. However, already at an Ag content as low as 1.8 at.% incorporated, SNMS showed a deterioration of the periodic multilayer structure. In agreement with the SNMS results, superlattice satellites were visible in the X-ray diffraction (XRD) patterns of the multilayers with up to 0.3 at.% Ag. The satellites were, however, very faint even for multilayers without Ag addition, indicating that the multilayers have high interface roughness and/or poor periodicity. In the absence of Ag and at the smallest Ag content investigated by XRD, a strong central multilayer peak and the weak superlattice satellites were complemented by weak diffraction maxima from non-periodic Co and Cu domains. In the Co/Cu(Ag) multilayer containing about 25 at.% Ag, i.e., nearly as much as Cu, XRD found a separate Ag(Cu) phase. In spite of the imperfect layered structure, a multilayer-type GMR behavior was observed in all samples up to about 10 at.% Ag incorporated in the multilayer stack. The GMR magnitude increased for Ag contents up to about 1 at.%, which implies that a small amount of Ag may have a beneficial effect through a slight modification of the layer growth and/or interface formation. However, for higher Ag contents beyond this level, the GMR was reduced in line with the structural degradation revealed by XRD and SNMS. For the highest Ag contents (above about 10 at.%), the GMR exhibited a behavior characteristic of a granular magnetic alloy, in agreement with the results of the structural study. One of the major obstacles hindering the realization of a high giant magnetoresistance (GMR) in electrodeposited (ED) ferromagnetic/non-magnetic (FM/NM) multilayers is that the nonmagnetic spacer layer cannot be electrodeposited as pinhole-free for layer thicknesses which are required to achieve high GMR and an oscillatory GMR behavior. 1 Sputtered Co/Cu multilayers 2-4 exhibit an oscillatory GMR and a room-temperature GMR of about 50% and 20% at about 1 and 2 nm Cu layer thicknesses, respectively. At these particular spacer thicknesses, a strong antiferromagnetic (AF) exchange coupling exists between the adjacent magnetic layers. It gives rise then to a large GMR effect since the AF coupling ensures an antiparallel alignment of the magnetizations of the neighboring magnetic layers in zero magnetic field. For spacer thicknesses between these so-called AF maxima, the exchange coupling is predominantly ferromagnetic. Thus, due to the parallel alignment of the layer magnetizations even in zero magnetic field, no GMR eff...