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Multilayer Thin Films (multilayer + thin_film)
Selected AbstractsMultifunctional FeCo/TiN Multilayer Thin Films with Combined Magnetic and Protective Properties,ADVANCED ENGINEERING MATERIALS, Issue 12 2009Christian Klever Abstract Coatings with thicknesses ranging from a few nanometer up to several micrometer produced by physical vapor deposition (PVD) processes have been established in engineering technologies since the early 1980s. In particular, magnetron sputtered wear resistance coatings are industrially established and capable to enhance tool lifetimes significantly. However, in cases where optical inspection of a coating in use is not possible, an intrinsic sensor function of the film would be beneficial. Therefore, the development of wear resistant coatings with an integrated sensor functionality based on the insertion of a magnetoelastic ferromagnetic phase is suggested. In combination with appropriate read-out electronics such a film system would be ready for online monitoring of the coatings' actual state (e.g., strain, temperature, volume loss). This paper focuses on the development of wear resistance coatings which simultaneously supply beneficial mechanical properties as well as ferromagnetic properties optimized for online non-contact read-out applications. Multilayer coatings obtained through alternate stacking of magnetron sputtered TiN and FeCo layers with a nominal total thickness of 1000,nm were produced as a model system meeting the above conditions. The bilayer period was varied down to 2.6,nm while the individual layer thickness ratio tTiN/tFeCo was determined by the deposition rates and maintained constant at a value of about 3/1. The films were vacuum annealed ex situ in a static magnetic field subsequent to the deposition. The constitution of the as-deposited and annealed coatings as well as their mechanical (nanohardness, Young's modulus) and magnetic properties (magnetization hysteresis, frequency-dependent permeability) are described. Finally, the suitability of the coatings for the use in remote-interrogable wear sensor applications is briefly discussed. [source] Multilayer Thin Films by Layer-by-Layer Assembly of Hole- and Electron-Transport Polyelectrolytes: Optical and Electrochemical PropertiesMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 20 2006Kyungsun Choi Abstract Summary: In this paper, we present the synthesis of a series of p-type and n-type semiconducting polyelectrolytes with triarylamine, oxadiazole, thiadiazole and triazine moieties. The synthesized polymeric hole and electron transport materials were examined optically and electrochemically using UV/Vis spectroscopy, PL spectroscopy and CV. Based on the optical and electrochemical data, each of the energy levels were calculated and all values suggested that they were promising hole- (p-type) or electron-transport (n-type) materials for devices. Moreover, the synthesized ionic polymers were suitable for LBL thin film deposition from dilute polymer solutions and the multilayers were fully characterized by UV/Vis, PL spectroscopy and CV. [source] Layer-by-Layer Deposition of Rhenium-Containing Hyperbranched Polymers and Fabrication of Photovoltaic CellsCHEMISTRY - A EUROPEAN JOURNAL, Issue 1 2007Chui Wan Tse Abstract Multilayer thin films were prepared by the layer-by-layer (LBL) deposition method using a rhenium-containing hyperbranched polymer and poly[2-(3-thienyl)ethoxy-4-butylsulfonate] (PTEBS). The radii of gyration of the hyperbranched polymer in solutions with different salt concentrations were measured by laser light scattering. A significant decrease in molecular size was observed when sodium trifluoromethanesulfonate was used as the electrolyte. The conditions of preparing the multilayer thin films by LBL deposition were studied. The growth of the multilayer films was monitored by absorption spectroscopy and spectroscopic ellipsometry, and the surface morphologies of the resulting films were studied by atomic force microscopy. When the pH of a PTEBS solution was kept at 6 and in the presence of salt, polymer films with maximum thickness were obtained. The multilayer films were also fabricated into photovoltaic cells and their photocurrent responses were measured upon irradiation with simulated air mass (AM) 1.5 solar light. The open-circuit voltage, short-circuit current, fill factor, and power conversion efficiency of the devices were 1.2 V, 27.1 ,,A,cm,2, 0.19, and 6.1×10,3,%, respectively. The high open-circuit voltage was attributed to the difference in the HOMO level of the PTEBS donor and the LUMO level of the hyperbranched polymer acceptor. A plot of incident photon-to-electron conversion efficiency versus wavelength also suggests that the PTEBS/hyperbranched polymer junction is involved in the photosensitization process, in which a maximum was observed at approximately 420 nm. The relatively high capacitance, determined from the measured photocurrent rise and decay profiles, can be attributed to the presence of large counter anions in the polymer film. [source] Evaluation of glucose sensitive affinity binding assay entrapped in fluorescent dissolved-core alginate microspheresBIOTECHNOLOGY & BIOENGINEERING, Issue 6 2009Ayesha Chaudhary Abstract The feasibility of dissolved-core alginate-templated fluorescent microspheres as "smart tattoo" glucose biosensors was investigated in simulated interstitial fluid (SIF). The sensor works on the principle of competitive binding and fluorescence resonance energy transfer. The sensor consists of multilayer thin film coated alginate microspheres incorporating dye-labeled glucose receptor and competing ligand within the partially dissolved alginate core. In this study, different approaches for the sensing and detection chemistry were studied, and the response of encapsulated reagents was compared with the solution-phase counterparts. The glucose sensitivity of the encapsulated TRITC-Con A/FITC-dextran (500,kDa) assay in DI water was estimated to be 0.26%/mM glucose while that in SIF was observed to be 0.3%/mM glucose. The glucose sensitivity of TRITC-apo-GOx/FITC-dextran (500,kDa) assay was estimated to be 0.33%/mM glucose in DI water and 0.5%/mM glucose in SIF and both demonstrated a response in the range of 0,50,mM glucose. Therefore, it is hypothesized that the calcium ion concentration outside the microsphere (in the SIF) does not interfere with the response sensitivity. The sensor response was observed to exhibit a maximum response time of 120,s. The system further exhibited a sensitivity of 0.94%/mM glucose with a response in range of 0,50,mM glucose, using near-infrared dyes (Alexa Fluor-647-labeled dextran as donor and QSY-21-conjugated apo-GOx as acceptor), thereby making the sensor more amenable to in vivo use, when implanted in scattering tissue. Biotechnol. Bioeng. 2009; 104: 1075,1085. © 2009 Wiley Periodicals, Inc. [source] Growth and characterisation of Zn:LiNbO3/Mg:LiNbO3 multilayer thin films grown by liquid phase epitaxyCRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2006H. J. Lee Abstract 1, 3 and 5 mol% ZnO doped LiNbO3 film and 2 mol% MgO doped LiNbO3 multilayer films were grown on the LiNbO3 (001) substrate by liquid phase epitaxy (LPE) method with a Li2O-V2O5 system. We examined the optical transmission spectra of the Zn:LiNbO3 by Fourier Transform-Infrared Spectrophotometer (FT-IR). The crystallinity and the lattice mismatch between the Zn:LiNbO3 film and Mg:LiNbO3 film was confirmed by x-ray rocking curve (XRC) and observed the ZnO and MgO distribution in the cross-section of the multilayer thin films by electron probe micro analyzer (EPMA). Furthermore, the surface morphology of the films was observed using atomic force microscopy (AFM). (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Anomalous Oxidation States in Multilayers for Fuel Cell ApplicationsADVANCED FUNCTIONAL MATERIALS, Issue 16 2010James M. Perkins Abstract Significant recent interest has been directed towards the relationship between interfaces and reports of enhanced ionic conductivity. To gain a greater understanding of the effects of hetero-interfaces on ionic conductivity, advanced analytical techniques including electron microscopy (TEM/STEM), electron energy loss spectroscopy (EELS), and secondary ion mass spectrometry (SIMS) are used to characterize CeO2/Ce0.85Sm0.15O2 multilayer thin films grown by pulsed laser deposition. High quality growth is observed, but ionic conductivity measured by impedance spectroscopy and 18O tracer experiments is consistent with bulk materials. EELS analysis reveals the unusual situation of layers containing only Ce(IV) adjacent to layers containing both Ce(III) and Ce(IV). Post oxygen annealing induced oxygen diffusion and mixed oxidation states in both layers, but only in the vicinity of low angle grain boundaries perpendicular to the layers. The implications of the anomalous behavior of the Ce oxidation states on the design of novel electrolytes for solid oxide fuel cells is discussed. [source] Layer-by-Layer Deposition of Rhenium-Containing Hyperbranched Polymers and Fabrication of Photovoltaic CellsCHEMISTRY - A EUROPEAN JOURNAL, Issue 1 2007Chui Wan Tse Abstract Multilayer thin films were prepared by the layer-by-layer (LBL) deposition method using a rhenium-containing hyperbranched polymer and poly[2-(3-thienyl)ethoxy-4-butylsulfonate] (PTEBS). The radii of gyration of the hyperbranched polymer in solutions with different salt concentrations were measured by laser light scattering. A significant decrease in molecular size was observed when sodium trifluoromethanesulfonate was used as the electrolyte. The conditions of preparing the multilayer thin films by LBL deposition were studied. The growth of the multilayer films was monitored by absorption spectroscopy and spectroscopic ellipsometry, and the surface morphologies of the resulting films were studied by atomic force microscopy. When the pH of a PTEBS solution was kept at 6 and in the presence of salt, polymer films with maximum thickness were obtained. The multilayer films were also fabricated into photovoltaic cells and their photocurrent responses were measured upon irradiation with simulated air mass (AM) 1.5 solar light. The open-circuit voltage, short-circuit current, fill factor, and power conversion efficiency of the devices were 1.2 V, 27.1 ,,A,cm,2, 0.19, and 6.1×10,3,%, respectively. The high open-circuit voltage was attributed to the difference in the HOMO level of the PTEBS donor and the LUMO level of the hyperbranched polymer acceptor. A plot of incident photon-to-electron conversion efficiency versus wavelength also suggests that the PTEBS/hyperbranched polymer junction is involved in the photosensitization process, in which a maximum was observed at approximately 420 nm. The relatively high capacitance, determined from the measured photocurrent rise and decay profiles, can be attributed to the presence of large counter anions in the polymer film. [source] | ||||||||||