515 results on '"Amorphous films"'
Search Results
452. MOLECULAR CIRCUIT DEVELOPMENT
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MELPAR FALLS CHURCH VA and MELPAR FALLS CHURCH VA
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Research and development was continued on mate rials and techniques suitable for the formation of molecular circuits. Material research concerned semiconductive films of silicon carbide, boron, and cadmium selenide and dielectric films of neodymium oxide. Chemical vapor depositions were successful in producing various types of crystallites and crystalline aggregates of silicon carbide; experiments aimed at obtaining uniform films were continued. Amorphous boron films, deposited by means of electron beam evaporation, proved useful in the study of electron transmission through thin films. This research indicates that amorphous films may possess valuable properties quite distinct from those representative of the crystalline state. An operating clipping circuit based on conduction through a boron film was devised. Investigations of dielectric films were concerned with the characterization of neodymium oxide. Deposition procedures were carefully investigated, and electrical properties evaluated over a wide temperature range. This material shows excellent capabilities for use as a high temperature dielectric. Work on field effect devices continued. Cadmium selenide remains the preferred material for the semiconductor film. The application of a field effect device in a current limiter circuit was studied. more...
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- 1963
453. DEVELOPMENT ON HIGH TEMPERATURE INSULATION MATERIALS. PART II. DEPOSITION AND PROPERTIES OF PYROLYTIC ALUMINUM AND SILICON NITRIDES
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WESTINGHOUSE RESEARCH LABS PITTSBURGH PA, Berg, D., Lewis, D. W., Dakin, T. W., Sestrich, D. E., Esposito, J. N., WESTINGHOUSE RESEARCH LABS PITTSBURGH PA, Berg, D., Lewis, D. W., Dakin, T. W., Sestrich, D. E., and Esposito, J. N. more...
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Pyrolytic aluminum nitride has been deposited on refractory electrical conductors using AlCl3.NH3 as the source material. Effects which pressure, temperature and rate of deposition have on electrical and other properties of deposits have been determined. Density of deposited coatings approach that of the calculated value. However, they still contain residual chlorine, causing electrical properties to fall short of what is expected of dense high purity AlN. Pyrolytic silicon nitride has been prepared from gaseous mixtures of silane and ammonia under varying conditions of temperature and pressure. Adherent, relatively soft, amorphous films have been deposited on substrates heated in the 700 to 800 C range while hard crystalline coatings of Alpha-Si3N4 have been obtained in the vicinity of 1250C. Coatings, which are both hard and amorphous, have been deposited at 1000C and have been characterized by a number of techniques. High temperature dielectric property tests of aluminum and silicon nitrides have indicated good high temperature resistivities with some samples, but considerable variability existed among samples. Measurements on aluminum nitride in particular, have indicated the presence of impurity conduction. Silicon nitride coatings seem to demonstrate more consistently high resistivities which make this material a potentially useful dielectric at 800 to 1000C at low voltages. more...
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- 1967
454. Electrical and Optical Properties of Amorphous Materials
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NORTHERN ILLINOIS UNIV DE KALB DEPT OF PHYSICS, Wood, Charles, NORTHERN ILLINOIS UNIV DE KALB DEPT OF PHYSICS, and Wood, Charles
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Research on Sb2Sn3 is reviewed covering spectroscopic studies of electron states of crystalline and amorphous forms, reflectivity and transmission measurements, photoemission, preparation and characterization of thin amorphous films, and thermopower and photothermopower measurements. Photoconductivity in antimony oxides is also discussed along with the Mossbauer effect of amorphous semiconductors and glasses., See also AD0753903. more...
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- 1973
455. Photoemission from Amorphous Silicon.
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YALE UNIV NEW HAVEN CONN DEPT OF ENGINEERING AND APPLIED SCIENCE, Fisher,Traugott E., Erbudak,Mehmet, YALE UNIV NEW HAVEN CONN DEPT OF ENGINEERING AND APPLIED SCIENCE, Fisher,Traugott E., and Erbudak,Mehmet more...
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Amorphous films were prepared by vapor quenching in ultra-high vacuum. n- and p-type silicon crystals were used as substrates and vapor source. The measurements (performed on clean and cesium covered surfaces) included photoelectric yield, energy distributions of photoelectrons, surface photovoltage, secondary emission with emphasis on elastic reflections, plasmon excitations, and Auger spectra. Information about densities of states, optical transitions, and position of Fermi level was obtained by direct comparison of photoelectric emission from the amorphous film, a silicon crystal, and a metal measured simultaneously. The results were found to depend on the mode of preparation and annealing of disordered films. (Author Modified Abstract), See also AD-719 562. more...
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- 1973
456. Structure, Properties and Radiation Sensitivity of Electrically Bistable Materials. Thermal Stability of As2Se3-As2Te3 Glasses
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FLORIDA UNIV GAINESVILLE ENGINEERING AND INDUSTRIAL EXPERIMENT STATION, Dove, Derek B, Loehman, Ronald E, FLORIDA UNIV GAINESVILLE ENGINEERING AND INDUSTRIAL EXPERIMENT STATION, Dove, Derek B, and Loehman, Ronald E more...
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The report contains some new measurements on the thermal stability of As2Se3-As2Te3 glasses in which multiple crystallization processes have been found by differential scanning calorimetry. Discussion is given of the structure of As2Se3 films by comparing intensity and rdf curves obtained experimentally with theoretical curves derived from a microcrystallite model. The data strongly indicates that a glassy network model is more in accord with the experimental rdf than a microcrystalline model. Continuation of the work on the interaction between As2Se3 and Cu support grids is indicative of the formation of Cu(2-x)Se upon heat treatment. Finally a review article on electron diffraction rdfs of amorphous films prepared for the Physics of Thin Films is included. more...
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- 1972
457. Electrical and Optical Properties of Amorphous Materials
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NORTHERN ILLINOIS UNIV DE KALB DEPT OF PHYSICS, Wood, Charles, NORTHERN ILLINOIS UNIV DE KALB DEPT OF PHYSICS, and Wood, Charles
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Research on Sb2Se3 is reviewed covering spectroscopic studies of electron states of crystalline and amorphous forms, reflectivity and transmission measurements, photoemission, resistivity vs. temperature studies, preparation and characterization of thin amorphous films, and thermopower and photothermopower measurements. Photoconductivity in antimony oxides is also discussed along with the Mossbauer effect of amorphous semiconductors and glasses., See also AD0744698. Sponsored in part by DARPA. more...
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- 1972
458. Electrical and Optical Properties of Amorphous Materials
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NORTHERN ILLINOIS UNIV DE KALB DEPT OF PHYSICS, Wood, Charles, NORTHERN ILLINOIS UNIV DE KALB DEPT OF PHYSICS, and Wood, Charles
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A very significant finding was that the standard method of preparing the amorphous forms of the Group V-VI compounds by vacuum evaporation from the compound is very unreliable from the compositional viewpoint. It appears probable that no data has ever been reported on truly 'Sb2Se3' amorphous films, despite considerable literature on the subject. Several approaches have been taken, or are under development, which have yielded amorphous Sb2Se3 films. Initial Mossbauer studies have shown that the Sb atoms in amorphous SbxSey (x 2, y 3) films differ in environment from the single crystal form and therefore appear to be amorphous rather than microcrystalline. Kramers-Kronig analysis of optical reflectivity data has been used extensively to analyze optical reflectivity data on single crystals and thin films. Highlights in the optical studies to date are: the band gap in Sb2Se3 appears to be due to a direct transition; plasma resonance frequencies can be accurately determined by thermoreflectance data; photon counter techniques show great promise in determining the critical points in band structure. more...
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- 1970
459. LOW TCC CAPACITORS FOR CIRCUIT APPLICATIONS
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HARRY DIAMOND LABS WASHINGTON D C, Isler,William E., Kitchman,Lester A., HARRY DIAMOND LABS WASHINGTON D C, Isler,William E., and Kitchman,Lester A.
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To meet requirements for temperature-stable components, an investigation into the temperature-dependence of capacitor dielectrics was undertaken. A review is given of the Gevers-du Pre theory of amorphous dielectrics, and its findings are examined for applicability to amorphous films of silicon monoxide (SiO). Films of SiO were deposited onto borosilicate glass substrates at rates ranging from 54 to 133 A/min. The values of the TCC showed a strong dependence upon the deposition rate; both negative and positive values were obtained--the former for the slower rates of deposition. All the TCC data agreed qualitatively with the Gevers-du Pre theory, which suggests that the negative TCC's are due to large expansion coefficients and low film densities obtained at slow deposition rates. The results of the present study also suggest that zero TCC's are possible and should occur at a rate near 68 A/min. (Author) more...
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- 1969
460. SPECIFIC HEAT AND HEAT OF CRYSTALLIZATION OF AMORPHOUS GERMANIUM.
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HARVARD UNIV CAMBRIDGE MASS DIV OF ENGINEERING AND APPLIED PHYSICS, Chen,H. S., Turnbull,D., HARVARD UNIV CAMBRIDGE MASS DIV OF ENGINEERING AND APPLIED PHYSICS, Chen,H. S., and Turnbull,D.
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The specific heat and heat of crystallization of vapor- and electro-deposited amorphous germanium were measured with a differential scanning calorimeter. The excess specific heat of the amorphous germanium over that of crystalline phase increased linearly with temperature over the temperature range from 215 to 460K. The heat of crystallization of the amorphous films was found to be about 2.75 k cal/gm-atom. The interpretation of the results in terms of the structure is discussed. The specific heat of crystalline germanium was also measured for the temperature range from 215 to 700K. (Author) more...
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- 1969
461. SUPPRESSION OF THE SEMICONDUCTOR-METAL TRANSITION IN VANADIUM OXIDES.
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RENSSELAER POLYTECHNIC INST TROY N Y, Kennedy,T. N., Mackenzie,J. D., RENSSELAER POLYTECHNIC INST TROY N Y, Kennedy,T. N., and Mackenzie,J. D.
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V2O3 and V2O4 films have been sputtered by a radio-frequency technique onto relatively cold substrates. The films were amorphous according to x-ray diffraction. Their electrical resistivities at-100C corresponded to that of the respective high temperature phases of the crystals. However, unlike the crystalline solids, the amorphous films did not exhibit the so-called semiconductor-metal transition. At 25C, because of the absence of this transition, the conductivity of amorphous V2O4 is almost four orders of magnitude greater than that of the crystal. (Author) more...
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- 1968
462. DEVELOPMENT ON HIGH TEMPERATURE INSULATION MATERIALS. PART I PYROLYTIC DEPOSITION OF ALUMINUM AND SILICON NITRIDES.
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WESTINGHOUSE RESEARCH LABS PITTSBURGH PA, Berg, D., Lewis, D. W., Dakin, T. W., Sestrich, D. E., Esposito, J. N., WESTINGHOUSE RESEARCH LABS PITTSBURGH PA, Berg, D., Lewis, D. W., Dakin, T. W., Sestrich, D. E., and Esposito, J. N. more...
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Aluminum nitride has been deposited on molybdenum, tungsten, and graphite by passing vapors of the AlCl3 NH3 complex over the hot substrates. Microstructure and density measurements indicate that the deposited material has a porosity of 20%. This and the presence of residual amounts of chlorine probably account for the high temperature electrical properties of the coating being poorer than expected of high purity aluminum nitride. Molybdenum substrates, when completely covered with these coatings are protected for oxidation by air at least up to 700 C. Pyrolytic silicon nitride has been prepared using SiF4 2NH3, SiCl4+NH3 and SiH4+NH3 as source materials. The gaseous mixture of silane and ammonia has been the most thoroughly studied and appears to be the most promising. Very adherent, relatively soft, amorphous films have been deposited on substrates heated in the 750 to 800 C range. Very hard crystalline coatings of Si3N4 were obtained in the 1100-1200 C range. These films have high spectral emissivity and provide oxidation protection for molybdenum substrates. more...
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- 1966
463. The growth, structure and properties of sputtered barium titanate thin films
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Newman, Robert M. and Newman, Robert M.
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The design and construction of a sputtering system for the deposition of barium titanate thin films is described. The growth and structure of barium titanate films deposited on a variety of substrates including amorphous carbon fi1ms, potassium bromide single crystals, and polycrystalline gold films has been studied. Films deposited on all substrates at room temperature were amorphous. Polycrystalline titanate films were formed on polycrystalline and amorphous substrates at temperatures above 450°C while films with a pronounced texture could be expitaxially deposited on single crystal potassium bromide above a temperature of only 200°C. Results of dielectric measurements made on the films are reported. Amorphous films were highly insulating (resistivities ~1014 ohm.cm with dielectric constants of between 10 and 20. more...
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- 1972
464. The growth, structure and properties of sputtered barium titanate thin films
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Newman, Robert M. and Newman, Robert M.
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The design and construction of a sputtering system for the deposition of barium titanate thin films is described. The growth and structure of barium titanate films deposited on a variety of substrates including amorphous carbon fi1ms, potassium bromide single crystals, and polycrystalline gold films has been studied. Films deposited on all substrates at room temperature were amorphous. Polycrystalline titanate films were formed on polycrystalline and amorphous substrates at temperatures above 450°C while films with a pronounced texture could be expitaxially deposited on single crystal potassium bromide above a temperature of only 200°C. Results of dielectric measurements made on the films are reported. Amorphous films were highly insulating (resistivities ~1014 ohm.cm with dielectric constants of between 10 and 20. more...
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- 1972
465. The growth, structure and properties of sputtered barium titanate thin films
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Newman, Robert M. and Newman, Robert M.
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The design and construction of a sputtering system for the deposition of barium titanate thin films is described. The growth and structure of barium titanate films deposited on a variety of substrates including amorphous carbon fi1ms, potassium bromide single crystals, and polycrystalline gold films has been studied. Films deposited on all substrates at room temperature were amorphous. Polycrystalline titanate films were formed on polycrystalline and amorphous substrates at temperatures above 450°C while films with a pronounced texture could be expitaxially deposited on single crystal potassium bromide above a temperature of only 200°C. Results of dielectric measurements made on the films are reported. Amorphous films were highly insulating (resistivities ~1014 ohm.cm with dielectric constants of between 10 and 20. more...
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- 1972
466. One-shot pair distribution functions of thin films using lab-based x-ray sources
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Bylin, Johan, Kapaklis, Vassilios, Pálsson, Gunnar K., Bylin, Johan, Kapaklis, Vassilios, and Pálsson, Gunnar K.
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We demonstrate the feasibility of obtaining accurate pair distribution functions of thin amorphous films down to 80 nm, using modern laboratory-based x-ray sources. The pair distribution functions are obtained using a single diffraction scan (one-shot) without the requirement of additional scans of the substrate or of the air. By using a crystalline substrate combined with an oblique scattering geometry, most of the Bragg scattering of the substrate is avoided, rendering the substrate Compton scattering the primary contribution. By utilizing a discriminating energy filter, available in the latest generation of modern detectors, we demonstrate that the Compton intensity can further be reduced to negligible levels at higher wavevector values. We minimize scattering from the sample holder and the air by the systematic selection of pixels in the detector image based on the projected detection footprint of the sample and the use of a 3D printed sample holder. Finally, x-ray optical effects in the absorption factors and the ratios between the Compton intensity of the substrate and film are taken into account by using a theoretical tool that simulates the electric field inside the film and the substrate, which aids in planning both the sample design and measurement protocol. more...
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467. Study of decagonal approximant and γ-brass-type compounds in Al-Cr-Fe thin films
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Demange, V., Ghanbaja, J., Beeli, C., Machizaud, F., Dubois, J.M., Demange, V., Ghanbaja, J., Beeli, C., Machizaud, F., and Dubois, J.M.
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This paper reports the preparation conditions and structure characteristics of Al-Cr-Fe very thin films (10-30 nm) obtained by the flash evaporation technique. The films are either amorphous or crystallized, depending on the thickness of the sample and temperature of the substrate. Annealing of amorphous films leads to crystallization of intermetallic phases that are all linked with quasicrystals. In particular, we have identified by transmission electron microscopy the following structures: body-centered-cubic (bcc) γ-brass phase, monoclinic λ-Al13(Cr,Fe)4 phase, and orthorhombic O1-phase, all of them already observed in this system, together with four new structures, i.e., a face-centered-cubic (fcc) γ-brass phase (superstructure of the bcc phase), monoclinic λ′-phase (related to the λ-phase) and two orthorhombic phases (1/1/; 1/1) and (1/0; 2/1) approximants of the decagonal phase). In this study, we point out the occurrence of twin defects of the λ-Al13(Cr,Fe)4 phase. Films prepared directly in the crystalline state comprise the O1 approximant. Electron energy loss spectroscopy measurements show that all films are not oxidized except for the presence of a native oxide layer that forms in ambient atmosphere with a thickness that cannot exceed 0.3 nm. Optical properties were investigated and show that films need to be large enough (>30 nm) to reproduce the properties of bulk alloys. Finally, contact angle wetting measurements reveal that the presence of such films on a substrate, even at very low thickness, considerably decreases the wetting behavior by water more...
468. Spectroscopic study of the photo-fixation of SO2 on anatase TiO2 thin films
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Topalian, Zareh, Niklasson, Gunnar A., Granqvist, Claes Göran, Österlund, Lars, Topalian, Zareh, Niklasson, Gunnar A., Granqvist, Claes Göran, and Österlund, Lars
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Photo-induced SO2 fixation on anatase TiO2 films was studied by in situ Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). The TiO2 films were prepared by reactive DC magnetron sputtering and were subsequently exposed to 50 ppm SO2 gas mixed in synthetic air and irradiated with UV light at substrate temperatures between 298 and 673 K. Simultaneous UV irradiation and SO2 exposure between 373 and 523 K resulted in significant sulfur deposits on crystalline TiO2 films as determined by XPS, whereas amorphous films contained negligible amounts of S. At substrate temperatures above 523 K, the S deposits readily desorbed from TiO2. The oxidation state of sulfur successively changed from S4+ for SO2 adsorbed on crystalline TiO2 films at room temperature without irradiation to S6+ for films exposed to SO2 at elevated temperatures with simultaneous irradiation. In situ FTIR was used to monitor the temporal evolution of the photo-induced surface reaction products formed on the TiO2 surfaces. It is shown that band gap excitation of TiO2 results in photo-induced oxidation of SO2 to form sulfide and sulfate ions, which at elevated temperatures become coordinated to the TiO2 lattice through interactions with O vacancies to form and species. These species makes the surface acidic, which is manifested in weak adherence of stearic acid. The films show good chemical stability as evidenced by sonication experiments. This suggests that photo-induced surface treatment in reactive sulfur gases may be interesting for fabrication of oleophobic and anti-greasing coatings. more...
469. Magneto-Optical properties of amorphous Fe-B-Nbthin films
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Masood, Ansar, Tamaki, T., Ström, Valter, Belova, Lyubov, Rao, K. V., Masood, Ansar, Tamaki, T., Ström, Valter, Belova, Lyubov, and Rao, K. V.
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Optically highly transparent, soft ferromagnetic thin films of Fe-B-Nb alloy grown on quartz by Pulse Laser Deposition (PLD) were investigated for structural, optical and magneto-optical properties. All deposited films revealed fully amorphous structure with very uniform thickness and surface morphology. Optical transmittance of 8 and 11nm thick films were found more than 60% over the entire visible regime (400-700nm). Verdet constant (V) and saturation Faraday rotation angle (θf) of studied films were increased linearly as a function of wavelength (λ) and considered appreciably high as compared to the reported magneto-optic materials, for example, 11nm thick film showed θf = 11.8deg/μm and V=21.4deg/Oe cm at λ=611nm. The combination of optical and magneto-optical properties with state of art fabrication process makes this kind of amorphous films interesting for optical telecommunication technology., Qc 20120906 more...
470. QUADRATIC OPTICAL NONLINEARITY OF AN AMORPHOUS HETEROJUNCTION
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AGAPOV A.Y., ZHITKOV P.M., FAVSTOV V.G., SHEVTSOV V.M., AGAPOV A.Y., ZHITKOV P.M., FAVSTOV V.G., and SHEVTSOV V.M.
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It has been shown experimentally, in the particular case of second-harmonic generation in a multilayer planar optical waveguide, that an amorphous heterojunction can have a significant quadratic nonlinearity. The possibility of "constructing" nonlinear media from ultrathin amorphous films is demonstrated. more...
471. Spectral Photosensitization of Optical Anisotropy in Solid Poly(Vinyl Cinnamate) Films
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Kozenkov V.M., Spakhov A.A., Belyaev V.V., Chausov D.N., Chigrinov V.G., Kozenkov V.M., Spakhov A.A., Belyaev V.V., Chausov D.N., and Chigrinov V.G.
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The possibility and features of formation of sensitized photoinduced optical anisotropy in amorphous films of poly(vinyl cinnamate) and its derivative poly(vinyl-4-metoxicinnamate) under the action of polarized light (including light that is not absorbed by polymer macromolecules themselves) have been investigated. It is found that the effect of induced optical anisotropy is based on the transfer of electron excitation energy from donor (sensitizer) molecules to acceptor molecules and is observed in the course of phototopochemical biomolecular cyclization reaction of cinnamate fragments in polymer macromolecules. The detected photoinduced anisotropy in solid films of poly(vinyl cinnamate) and its derivative poly(vinyl-4-metoxicinnamate) ensures sensitized photo-orientation of low-molecular thermotropic liquid crystals. © 2018, Pleiades Publishing, Ltd. more...
472. The energetics of the semiconducting polymer-electrode interface for solution-processed electronics
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Bao, Qinye, Fabiano, Simone, Andersson, Mattias, Braun, Slawomir, Sun, Zhengyi, Crispin, Xavier, Berggren, Magnus, Liu, Xianjie, Fahlman, Mats, Bao, Qinye, Fabiano, Simone, Andersson, Mattias, Braun, Slawomir, Sun, Zhengyi, Crispin, Xavier, Berggren, Magnus, Liu, Xianjie, and Fahlman, Mats more...
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The semiconductor-electrode interface impacts the function and the performance of (opto-)electronic devices. For printed organic electronics the electrode surface is not atomically clean leading to weakly interacting interfaces. As a result, solution-processed organic ultra-thin films on electrodes typically form islands due to de-wetting. It has therefore been utterly difficult to achieve homogenous ultrathin conjugated polymer films. This has made the investigation of the correct energetics of the conjugated polymer-electrode interface impossible. Also, this has hampered the development of devices including ultra-thin conjugated polymer layers. Here, we report Langmuir-Shäfer-manufactured homogenous mono- and multilayers of semiconducting polymers on metal electrodes and track the energy level bending using photoelectron spectroscopy. The amorphous films display an abrupt energy level bending that does not extend beyond the first monolayer. Our findings provide new insights of the energetics of the polymer-electrode interface and opens up for new high-performing devices based on ultra-thin semiconducting polymers. more...
473. Growth mechanisms and near-interface structure in relation to orientation of MoS2 sputtered thin films
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Moser, J., Lévy, F., Moser, J., and Lévy, F.
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The growth of sputter-deposited MoS2 thin films is investigated by high-resolution transmission electron microscopy. Pure high-temperature grown films are compared with H2O-contaminated films and amorphous annealed films. In the first case, the films are oriented. They have a first interface layer with crystallites having their (002) planes parallel with the substrate. The subsequent growth leads to the already described lamellar structure, with flakes perpendicular to the substrate. This structure can be explained in terms of a local branching process during crystal growth. The orientation relations between the crystallites in the parallel layer and the lamellae are determined. The local structure at the root of the lamellae, as well as at the interface, is investigated by image calculation. Water contamination in the plasma is shown to result in an amorphization of the interfacial region, followed by lamellar growth. Amorphous films annealed under vacuum do not show a lamellar structure, but have isotropic crystallization. In each of these cases, the mechanism determining the film structure is different more...
474. Microstructure and electrical conductivity of YSZ thin films prepared by pulsed laser deposition
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Heiroth, S., Lippert, Th, Wokaun, A., Döbeli, M., Heiroth, S., Lippert, Th, Wokaun, A., and Döbeli, M.
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Yttria-stabilized zirconia (YSZ) is the most common solid electrolyte material used e.g. in ceramic fuel cells. Thin films of YSZ were deposited on c-cut sapphire single crystals by pulsed laser deposition using a KrF excimer laser focused on a polycrystalline 8 mol% Y2O3-stabilized ZrO2 target. Depending on the substrate temperature and the oxygen background pressure during deposition, different microstructures are obtained. XRD and high-resolution SEM revealed the formation of dense amorphous films at room temperature. At 600°C preferentially (111) oriented polycrystalline films consisting of densely agglomerated nm-sized grains of the cubic phase resulted. Grain size and surface roughness could be controlled by varying the oxygen background pressure. RBS and PIXE evidenced congruent transfer only for a low number of pulses, indicating a dynamical change of the target stoichiometry during laser irradiation. The in-plane ionic conductivity of the as-deposited crystalline films was comparable to bulk YSZ. The conductivity of initially amorphous YSZ passes a maximum during the crystallization process. However, the relative changes remain small, i.e. no significant enhancement of ionic conductivity related to the formation of a nanocrystalline microstructure is found more...
475. Orientation of rapid thermally annealed lead zirconate titanate thin films on (111) Pt substrates
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Brooks, Keith G., Reaney, Ian M., Klissurska, Radosveta, Huang, Y., Bursill, L., Setter, N., Brooks, Keith G., Reaney, Ian M., Klissurska, Radosveta, Huang, Y., Bursill, L., and Setter, N.
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The nucleation, growth, and orientation of lead zirconate titanate thin films prepared from organometallic precursor solutions by spin coating on (111) oriented platinum substrates and crystallized by rapid thermal annealing was investigated. The effects of pyrolysis temperature, post-pyrolysis thermal treatments, and excess lead addition are reported. The use of post-pyrolysis oxygen anneals at temperatures in the regime of 350-450 °C was found to strongly affect the kinetics of subsequent amorphous-pyrochlore-perovskite crystallization by rapid thermal annealing. The use of such post-pyrolysis anneals allowed films of reproducible microstructure and textures [both (100) and (111)] to be prepared by rapid thermal annealing. It is proposed that such anneals and pyrolysis temperature affect the oxygen concentration/average Pb valence in the amorphous films prior to annealing. Such changes in the Pb valence state then affect the stability of the transient pyrochlore phase and thus the kinetics of perovskite crystallization more...
476. Crystal reorientation and wear mechanisms in MoS2 lubricating thin films investigated by TEM
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Moser, J., Lévy, F., Moser, J., and Lévy, F.
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MoS2 thin films are sputter-deposited in different conditions in order to obtain well-defined microstructures. They are submitted to ball-on-disk wear tests at moderate loads (0.7 GPa). Cross sections of wear tracks are observed by transmission electron microscopy (TEM). Sliding induces the formation and the wear of a lubricating buffer layer between the film and the sliding ball. This buffer layer shows strong crystal reorientation, suggesting the presence of intergranular motion. Initially amorphous films crystallize during the sliding test. The film's intrinsic failure mechanisms appear to be more determinant for the sliding lifetime than the properties of the interface more...
477. Depozice a charakterizace tenkých vrstev systému Ge-As-S
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Pálka, Karel, Janíček, Petr, Kubíčková, Michaela, Pálka, Karel, Janíček, Petr, and Kubíčková, Michaela
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Tato diplomová práce se zabývá přípravou a charakterizací tenkých amorfních vrstev chalkogenidových skel systému GexAs30-xS70 (kde x = 0, 4, 8, 12, 16) připravených metodou vakuového napařování a metodou spin-coating. Byl studován vliv temperace a expozice UV zářením na změnu optických parametrů, složení a strukturu tenkých vrstev., This diploma thesis deals with preparation and characterization of GexAs30-xS70 (where x = 0, 4, 8, 12, 16) thin amorphous chalcogenide films deposited by spin-coating and vacuum thermal evaporation method. The effects of annealing and exposure to UV radiation on the change of optical parameters, composition and thin film structure were studied., Fakulta chemicko-technologická, Dokončená práce s úspěšnou obhajobou more...
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- 2017
478. Adsorption of Xyloglucan onto Cellulose Surfaces of Different Morphologies : An Entropy-Driven Process
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Benselfelt, Tobias, Cranston, Emily D., Ondaral, Sedat, Johansson, Erik, Brumer, Harry, Rutland, Mark W., Wågberg, Lars, Benselfelt, Tobias, Cranston, Emily D., Ondaral, Sedat, Johansson, Erik, Brumer, Harry, Rutland, Mark W., and Wågberg, Lars more...
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The temperature-dependence of xyloglucan (XG) adsorption onto smooth cellulose model films regenerated from N-methylmorpholine N-oxide (NMMO) was investigated using surface plasmon resonance spectroscopy, and it was found that the adsorbed amount increased with increasing temperature. This implies that the adsorption of XG to NMMO-regenerated cellulose is endothermic and supports the hypothesis that the adsorption of XG onto cellulose is an entropy-driven process. We suggest that XG adsorption is mainly driven by the release of water molecules from the highly hydrated cellulose surfaces and from the XG molecules, rather than through hydrogen bonding and van der Waals forces as previously suggested. To test this hypothesis, the adsorption of XG onto cellulose was studied using cellulose films with different morphologies prepared from cellulose nanocrystals (CNC), semicrystalline NMMO-regenerated cellulose, and amorphous cellulose regenerated from lithium chloride/dimethylacetamide. The total amount of high molecular weight xyloglucan (XGHMW) adsorbed was studied by quartz crystal microbalance and reflectometry measurements, and it was found that the adsorption was greatest on the amorphous cellulose followed by the CNC and NMMO-regenerated cellulose films. There was a significant correlation between the cellulose dry film thickness and the adsorbed XG amount, indicating that XG penetrated into the films. There was also a correlation between the swelling of the films and the adsorbed amounts and conformation of XG, which further strengthened the conclusion that the water content and the subsequent release of the water upon adsorption are important components of the adsorption process., QC 20161005 more...
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- 2016
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479. Continuously operating biosensor and its integration into a hermetically sealed medical implant
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Birkholz, Mario, Glogener, Paul, Glös, Franziska, Basmer, Thomas, Theuer, Lorenz, Birkholz, Mario, Glogener, Paul, Glös, Franziska, Basmer, Thomas, and Theuer, Lorenz
- Abstract
An integration concept for an implantable biosensor for the continuous monitoring of blood sugar levels is presented. The system architecture is based on technical modules used in cardiovascular implants in order to minimize legal certification efforts for its perspective usage in medical applications. The sensor chip operates via the principle of affinity viscometry, which is realized by a fully embedded biomedical microelectromechanical systems (BioMEMS) prepared in 0.25-μm complementary metal-oxide-semiconductor (CMOS)/BiCMOS technology. Communication with a base station is established in the 402-405 MHz band used for medical implant communication services (MICS). The implant shall operate within the interstitial tissue, and the hermetical sealing of the electronic system against interaction with the body fluid is established using titanium housing. Only the sensor chip and the antenna are encapsulated in an epoxy header closely connected to the metallic housing. The study demonstrates that biosensor implants for the sensing of low-molecular-weight metabolites in the interstitial may successfully rely on components already established in cardiovascular implantology., Funding details: 16SV3934, BMBF, Bundesministerium für Bildung und Forschung more...
- Published
- 2016
- Full Text
- View/download PDF
480. Continuously operating biosensor and its integration into a hermetically sealed medical implant
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Birkholz, Mario, Glogener, Paul, Glös, Franziska, Basmer, Thomas, Theuer, Lorenz, Birkholz, Mario, Glogener, Paul, Glös, Franziska, Basmer, Thomas, and Theuer, Lorenz
- Abstract
An integration concept for an implantable biosensor for the continuous monitoring of blood sugar levels is presented. The system architecture is based on technical modules used in cardiovascular implants in order to minimize legal certification efforts for its perspective usage in medical applications. The sensor chip operates via the principle of affinity viscometry, which is realized by a fully embedded biomedical microelectromechanical systems (BioMEMS) prepared in 0.25-μm complementary metal-oxide-semiconductor (CMOS)/BiCMOS technology. Communication with a base station is established in the 402-405 MHz band used for medical implant communication services (MICS). The implant shall operate within the interstitial tissue, and the hermetical sealing of the electronic system against interaction with the body fluid is established using titanium housing. Only the sensor chip and the antenna are encapsulated in an epoxy header closely connected to the metallic housing. The study demonstrates that biosensor implants for the sensing of low-molecular-weight metabolites in the interstitial may successfully rely on components already established in cardiovascular implantology., Funding details: 16SV3934, BMBF, Bundesministerium für Bildung und Forschung more...
- Published
- 2016
- Full Text
- View/download PDF
481. Příprava a charakterizace tenkých vrstev Al2O3
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Němec, Petr, Schwarz, Jiří, Karhánek, Milan, Němec, Petr, Schwarz, Jiří, and Karhánek, Milan
- Abstract
Tato práce se zabývá přípravou a charakterizací amorfních ultratenkých vrstev oxidu hlinitého (Al2O3) deponovaných pomocí elektronového svazku (EB-PVD). Sleduje topografii, složení a optické vlastnosti připravených tenkých vrstev v závislosti na jejich tloušťce a depozičních podmínkách s cílem nalézt co nejtenčí kontinuální vrstvu Al2O3. Zejména byl sledován vliv rychlosti depozice a prostředí v depoziční komoře (přítomnost či nepřítomnost O2). Povrchová hrubost připravených vrstev Al2O3 byla sledována pomocí AFM (atomic force microscopy). Topografie deponovaných vrstev byla studována skenovací elektronovou mikroskopií. Chemické složení vrstev bylo stanoveno pomocí SEM-EDX (scanning electron microscopy-energy dispersive X-ray spectroscopy). Optické vlastnosti (index lomu, extinkční koeficient), tloušťky a procentuální zastoupení dutin v těchto vrstvách byly určeny analýzou elipsometrických dat. Amorfní charakter připravených vrstev Al2O3 byl potvrzen pomocí XRD (X-ray diffraction)., This work deals with the fabrication and characterization of ultra thin films of amorphous alumina (Al2O3) which were prepared using electron beam deposition (EB-PVD). Topography, composition and optical properties of fabricated thin films were investigated depending on their thickness and deposition conditions aimed to find the thinnest continuous film of Al2O3. The influence of deposition rate under vacuum or background gas environment (O2) was studied. The surface roughness of Al2O3 thin films was investigated by AFM (atomic force microscopy). The topography of deposited layers was studied by scanning electron microscopy. The chemical composition of the films was determined via SEM-EDX (scanning electron microscopy-energy dispersive X-ray spectroscopy). Optical properties (refractive index, extinction coefficient), thicknesses and the percentage of voids in the films were evaluated through the analysis of ellipsometric data. Amorphous character of fabricated Al2O3 films was confirmed by XRD (X-ray diffraction)., Fakulta chemicko-technologická, Dokončená práce s úspěšnou obhajobou more...
- Published
- 2016
482. In Situ Formation of Efficient Cobalt-Based Water Oxidation Catalysts from Co2+-Containing Tungstate and Molybdate Solutions
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Zhang, B., Wu, X., Li, F., Yu, F., Wang, Y., Sun, Licheng, Zhang, B., Wu, X., Li, F., Yu, F., Wang, Y., and Sun, Licheng
- Abstract
Replacing rare and expensive noble-metal catalysts with inexpensive and earth-abundant ones is of great importance to split water either electrochemically or photoelectrochemically. In this study, two amorphous cobalt oxide catalysts (Co-W film and Co-Mo film) with high activity for electrocatalytic water oxidation were prepared by fast, simple electrodeposition from aqueous solutions of Na2WO4 and Na2MoO4 containing Co2+. In solutions of Na2WO4 and Na2MoO4, sustained anodic current densities up to 1.45 and 0.95mA cm-2 were obtained for Co-W film at 1.87V versus a reversible hydrogen electrode (RHE) and Co-Mo film on fluorine-doped tin oxide (FTO) substrates at 1.85V versus RHE. For the Co-W film, a much higher current density of 4.5mA cm-2 was acquired by using a stainless-steel mesh as the electrode substrate. Significantly, in long-term electrolysis for 13h, the Co-W film exhibited improved stability in cobalt-free buffer solution in comparison with the previously reported Co-Pi film., Funding Details: 21476043, NSFC, National Natural Science Foundation of ChinaQC 20160218 more...
- Published
- 2015
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483. Magnetic properties of amorphous Fe93Zr7 films : Effect of light ion implantation
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Zamani, A., Moubah, R., Ahlberg, M., Stopfel, H., Arnalds, U. B., Hallén, Anders, Hjörvarsson, B., Andersson, G., Jönsson, P. E., Zamani, A., Moubah, R., Ahlberg, M., Stopfel, H., Arnalds, U. B., Hallén, Anders, Hjörvarsson, B., Andersson, G., and Jönsson, P. E. more...
- Abstract
The Curie temperature (Tc) of amorphous FeZr alloys can be greatly enhanced by doping with light elements. In this investigation, ion implantation is used to dope Fe93Zr7 thin films with H, He, B, C, and N. Extended X-ray absorption fine structure measurements confirm that the amorphous structure is preserved upon implantation for all samples, except for the N-implanted sample which is partially crystallized. The Curie temperature increases from 124 K for the pristine FeZr sample to about 400 K for the (FeZr)B0.11 sample. The increase of Tc is proportional to the increase in the average Fe-Fe distance, which allows us to conclude that the dominant cause of the Tc enhancement of amorphous Fe93Zr7 upon doping is a volume effect., QC 20150528 more...
- Published
- 2015
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484. Recombination and thin film properties of silicon nitride and amorphous silicon passivated c-Si following ammonia plasma exposure
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Wan, Yimao, McIntosh, Keith R., Thomson, Andrew F., Cuevas, Andres, Wan, Yimao, McIntosh, Keith R., Thomson, Andrew F., and Cuevas, Andres
- Abstract
Recombination at silicon nitride (SiNx) and amorphous silicon (a-Si) passivated crystalline silicon (c-Si) surfaces is shown to increase significantly following an ammonia (NH₃) plasma exposure at room temperature. The effect of plasma exposure on chemical structure, refractive index, permittivity, and electronic properties of the thin films is also investigated. It is found that the NH₃ plasma exposure causes (i) an increase in the density of Si≡N₃ groups in both SiNx and a-Si films, (ii) a reduction in refractive index and permittivity, (iii) an increase in the density of defects at the SiNx/c-Si interface, and (iv) a reduction in the density of positive charge in SiNx. The changes in recombination and thin film properties are likely due to an insertion of N–H radicals into the bulk of SiNx or a-Si. It is therefore important for device performance to minimize NH₃ plasma exposure of SiNx or a-Si passivating films during subsequent fabrication steps. more...
- Published
- 2015
485. Sputter deposition of transition-metal carbide films - A critical review from a chemical perspective
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Jansson, Ulf, Lewin, Erik, Jansson, Ulf, and Lewin, Erik
- Abstract
Thin films based on transition-metal carbides exhibitmany interesting physical and chemical properties making them attractive for a variety of applications. The most widely used method to produce metal carbide films with specific properties at reduced deposition temperatures is sputter deposition. A large number of papers in this field have been published during the last decades, showing that large variations in structure and properties can be obtained. This review will summarise the literature on sputter-deposited carbide films based on chemical aspects of the various elements in the films. By considering the chemical affinities (primarily towards carbon) and structural preferences of different elements, it is possible to understand trends in structure of binary transition-metal carbides and the ternary materials based on these carbides. These trends in chemical affinity and structure will also directly affect the growth process during sputter deposition. A fundamental chemical perspective of the transition-metal carbides and their alloying elements is essential to obtain control of the material structure (from the atomic level), and thereby its properties and performance. This review covers a wide range of materials: binary transition-metal carbides and their nanocomposites with amorphous carbon; the effect of alloying carbide-based materials with a third element (mainly elements from groups 3 through 14); as well as the amorphous binary and ternary materials from these elements deposited under specific conditions or at certain compositional ranges. Furthermore, the review will also emphasise important aspects regarding materials characterisation which may affect the interpretation of data such as beam-induced crystallisation and sputter-damage during surface analysis. more...
- Published
- 2013
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486. Enhanced thermal stability and electrical behavior of Zn-doped Sb2Te films for phase change memory application
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Shen, Xiang, Wang, Guoxiang, Wang, R. P., Dai, Shixun, Wu, Liangcai, Chen, Yimin, Xu, Tiefeng, Nie, Qiuhua, Shen, Xiang, Wang, Guoxiang, Wang, R. P., Dai, Shixun, Wu, Liangcai, Chen, Yimin, Xu, Tiefeng, and Nie, Qiuhua more...
- Abstract
Zn-doped Sb₂Te films are proposed to present the feasibility for phase-change memory application. Zn atoms are found to significantly increase crystallization temperature of Zn x (Sb₂Te)1−x films and be almost linearly with the wide range of Zn-doping concentration from x = 0 to 29.67 at.%. Crystalline resistances are enhanced by Zn-doping, while keeping the large amorphous/crystalline resistance ratio almost constant at ∼10⁵. Especially, the Zn 26.07 (Sb₂Te)73.93 and Zn 29.67 (Sb₂Te)70.33 films exhibit a larger resistance change, faster crystallization speed, and better thermal stability due to the formation of amorphous Zn-Sb and Zn-Te phases as well as uniform distribution of Sb₂Te crystalline grains. more...
- Published
- 2013
487. Improved phase-change characteristics of Zn-doped amorphous Sb₇Te₃ films for high-speed and low-power phase change memory
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Wang, Guoxiang, Shen, Xiang, Nie, Qiuhua, Wang, R. P., Wu, Liangcai, Lu, Yegang, Dai, Shixun, Xu, Tiefeng, Chen, Yimin, Wang, Guoxiang, Shen, Xiang, Nie, Qiuhua, Wang, R. P., Wu, Liangcai, Lu, Yegang, Dai, Shixun, Xu, Tiefeng, and Chen, Yimin more...
- Abstract
The superior performance of Zn-doped Sb₇Te₃ films might be favorable for the application in phase change memory. It was found that Zn dopants were able to suppress phase separation and form single stable Sb2Te crystal grain, diminish the grain size, and enhance the amorphous thermal stability of Sb₇Te₃ film. Especially, Zn 30.19(Sb₇Te₃)69.81 film has higher crystallization temperature (∼258 °C), larger crystallization activation energy (∼4.15 eV), better data retention (∼170.6 °C for 10 yr), wider band gap (∼0.73 eV), and higher crystalline resistance. The minimum times for crystallization of Zn 30.19(Sb₇Te₃)69.81 were revealed to be as short as ∼10 ns at a given proper laser power of 70 mW. more...
- Published
- 2013
488. A grain boundary phase transition in Si-Au
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Ma, Shuailei, Asl, Kaveh Meshinchi, Tansarawiput, Chookiat, Cantwell, Patrick R., Qi, Minghao, Harmer, Martin P., Luo, Jian, Ma, Shuailei, Asl, Kaveh Meshinchi, Tansarawiput, Chookiat, Cantwell, Patrick R., Qi, Minghao, Harmer, Martin P., and Luo, Jian more...
- Abstract
A grain boundary transition from a bilayer to an intrinsic (nominally clean) boundary is observed in Si-Au. An atomically abrupt transition between the two complexions (grain boundary stabilized phases) implies the occurrence of a first-order interfacial phase transition associated with a discontinuity in the interfacial excess. This observation supports a grain-boundary complexion theory with broad applications. This transition is atypical in that the monolayer complexion is absent. A model is proposed to explain the bilayer stabilization and the origin of this complexion transition. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. more...
- Published
- 2012
489. A grain boundary phase transition in Si-Au
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Ma, Shuailei, Asl, Kaveh Meshinchi, Tansarawiput, Chookiat, Cantwell, Patrick R., Qi, Minghao, Harmer, Martin P., Luo, Jian, Ma, Shuailei, Asl, Kaveh Meshinchi, Tansarawiput, Chookiat, Cantwell, Patrick R., Qi, Minghao, Harmer, Martin P., and Luo, Jian more...
- Abstract
A grain boundary transition from a bilayer to an intrinsic (nominally clean) boundary is observed in Si-Au. An atomically abrupt transition between the two complexions (grain boundary stabilized phases) implies the occurrence of a first-order interfacial phase transition associated with a discontinuity in the interfacial excess. This observation supports a grain-boundary complexion theory with broad applications. This transition is atypical in that the monolayer complexion is absent. A model is proposed to explain the bilayer stabilization and the origin of this complexion transition. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. more...
- Published
- 2012
490. Te-based chalcogenide films with high thermal stability for phase change memory
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Wang, Guoxiang, Shen, Xiang, Nie, Qiuhua, Chen, Fen, Wang, Xunsi, Fu, Jing, Chen, Yu, Xu, Tiefeng, Dai, Shixun, Zhang, Wei, Wang, Rongping, Wang, Guoxiang, Shen, Xiang, Nie, Qiuhua, Chen, Fen, Wang, Xunsi, Fu, Jing, Chen, Yu, Xu, Tiefeng, Dai, Shixun, Zhang, Wei, and Wang, Rongping more...
- Abstract
This study reports on the synthesis of tellurium-based chalcogenide films that have high thermal stability for phase change memory application. Several Te-based chalcogenide alloys of In-Bi-Te, Ag-Bi-Te, In-Sb-Te, Sn-Sb-Te, Zn-Ge-Te, and Ga-Ge-Te are reported. Their thermal, optical, and electrical properties are investigated. The results show that Bi-Te-based films have a higher crystallization temperature and greater activation energy compared with the other Sb-Te-based and Ge-Te-based films. Especially, In₂.₈Bi₃₆.₆Te₆₀.₆film exhibits high crystallization temperature (252 °C) and great activation energy (5.16 eV), showing much improved amorphous thermal stability. A relatively wider optical band gap (0.674 eV) of thermal annealed In₂.₈Bi₃₆.₆Te₆₀.₆film is obtained. In addition, it also has a higher amorphous/crystalline resistance ratio of about 10⁵, implying that current consumption could be low in the phase-change memory operation. more...
- Published
- 2012
491. Structural evolution of Ge 2 Sb 2 Te 5 films under the 488 nm laser irradiation
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Fu, Jing, Shen, Xiang, Xu, Yinsheng, Wang, Guoxiang, Nie, Qiuhua, Lin, Changgui, Dai, Shixun, Xu, Tiefeng, Wang, Rongping, Fu, Jing, Shen, Xiang, Xu, Yinsheng, Wang, Guoxiang, Nie, Qiuhua, Lin, Changgui, Dai, Shixun, Xu, Tiefeng, and Wang, Rongping more...
- Abstract
Ge 2Sb 2Te 5 films were locally crystallized by a tightly focused laser beam and the structural evolution was studied by Raman scatting. The marks recorded by a broad range of laser power were studied by optical microscope. Raman spectra of films with irradiation power of 0.1 mW and 1 mW were consistent with those of films annealed at 140°C and 400°C, respectively. It reveals that both the cubic and hexagonal crystalline phases have been achieved under the irradiation of 488 nm laser in amorphous Ge 2Sb 2Te 5 films. Specifically, the appearance of a new band of ∼141 cm -1 in films with irradiation power larger than 1.25 mW confirms that the over-irradiation causes the segregation of Te crystalline phase in films. more...
- Published
- 2012
492. A grain boundary phase transition in Si-Au
- Author
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Ma, Shuailei, Asl, Kaveh Meshinchi, Tansarawiput, Chookiat, Cantwell, Patrick R., Qi, Minghao, Harmer, Martin P., Luo, Jian, Ma, Shuailei, Asl, Kaveh Meshinchi, Tansarawiput, Chookiat, Cantwell, Patrick R., Qi, Minghao, Harmer, Martin P., and Luo, Jian more...
- Abstract
A grain boundary transition from a bilayer to an intrinsic (nominally clean) boundary is observed in Si-Au. An atomically abrupt transition between the two complexions (grain boundary stabilized phases) implies the occurrence of a first-order interfacial phase transition associated with a discontinuity in the interfacial excess. This observation supports a grain-boundary complexion theory with broad applications. This transition is atypical in that the monolayer complexion is absent. A model is proposed to explain the bilayer stabilization and the origin of this complexion transition. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. more...
- Published
- 2012
493. A grain boundary phase transition in Si-Au
- Author
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Ma, Shuailei, Asl, Kaveh Meshinchi, Tansarawiput, Chookiat, Cantwell, Patrick R., Qi, Minghao, Harmer, Martin P., Luo, Jian, Ma, Shuailei, Asl, Kaveh Meshinchi, Tansarawiput, Chookiat, Cantwell, Patrick R., Qi, Minghao, Harmer, Martin P., and Luo, Jian more...
- Abstract
A grain boundary transition from a bilayer to an intrinsic (nominally clean) boundary is observed in Si-Au. An atomically abrupt transition between the two complexions (grain boundary stabilized phases) implies the occurrence of a first-order interfacial phase transition associated with a discontinuity in the interfacial excess. This observation supports a grain-boundary complexion theory with broad applications. This transition is atypical in that the monolayer complexion is absent. A model is proposed to explain the bilayer stabilization and the origin of this complexion transition. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. more...
- Published
- 2012
494. Highly amorphous Fe90Zr10 thin films, and the influence of crystallites on the magnetism
- Author
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Korelis, Panagiotis T., Liebig, Andreas, Björck, Matts, Hjörvarsson, Björgvin, Lidbaum, Hans, Leifer, Klaus, Wildes, A. R., Korelis, Panagiotis T., Liebig, Andreas, Björck, Matts, Hjörvarsson, Björgvin, Lidbaum, Hans, Leifer, Klaus, and Wildes, A. R. more...
- Abstract
A method for depositing highly amorphous, iron-rich Fe100-xZrx thin films on to room temperature substrates is presented. The method involves co-depositing Fe and Zr on to an amorphous AlZr layer. Experimental proof that the structures are completely amorphous is given by transmission electron microscopy and polarized neutron reflectometry. The reflectometry measurements also give an indication of the impact that Fe crystallite impurities have on the magnetic structure and properties of amorphous FeZr. The results are consistent with previous investigations on bulk samples, which showed that crystalline impurities make the magnetic structure more non-collinear. more...
- Published
- 2010
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495. The effect of deposition energy on the microstructure and mechanical properties of high speed steel films prepared using a filtered cathodic vacuum arc
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Pagon, A. M., Partridge, J. G., Hubbard, P, Taylor, M. B., McCulloch, Dougal G, Doyle, Edward Dermot, Latham, K, Bradby, Jodie, Borisenko, K. B., Li, G, Pagon, A. M., Partridge, J. G., Hubbard, P, Taylor, M. B., McCulloch, Dougal G, Doyle, Edward Dermot, Latham, K, Bradby, Jodie, Borisenko, K. B., and Li, G more...
- Abstract
Energetic deposition of high speed steel (HSS) films has been performed using a filtered cathodic vacuum arc system fitted with a AISI M2 HSS cathode. The mechanical properties and microstructure of the films were investigated as a function of the deposition energy. The stoichiometry and microstructure of the deposited films were different to that of the cathode and a dependence on the deposition energy was found. Films deposited at low deposition energies (<100 eV) exhibited reduced concentrations of Mo and W and a smaller average crystallite size than the M2 HSS cathode. These films were found to be significantly harder than the M2 HSS cathode, possibly due to their smaller average crystallite size. A HSS film consisting of an amorphous phase with isolated crystals of bcc Fe was produced using high deposition energy and the deposition rate was found to decrease, likely due to sputtering. more...
- Published
- 2010
496. Local setting of magnetic anisotropy in FeCoSiB thin films by means of indirect ion implantation
- Author
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Martin, N., McCord, J., Gerber, A., Strache, T., Gemming, T., Mönch, I., Schäfer, R., (0000-0003-3893-9630) Fassbender, J., Quandt, E., Schultz, L., Martin, N., McCord, J., Gerber, A., Strache, T., Gemming, T., Mönch, I., Schäfer, R., (0000-0003-3893-9630) Fassbender, J., Quandt, E., and Schultz, L. more...
- Abstract
The magnetic anisotropy direction and strength of amorphous FeCoSiB thin films was modified locally by masked ion implantation without alteration of the magnetic materials structure and the intrinsic magnetic properties of the ferromagnetic film. The changes were introduced by local ion implantation in a SiO2 covering and protection layer, inducing additional stress-induced magnetic anisotropy to the magnetostrictive ferromagnetic layer. Hybrid hysteresis curves combining switching and rotational processes were measured and the underlying local variation of magnetic anisotropy was confirmed by magnetic domain observations. A good agreement between the calculated stress distribution and the experimentally obtained magnetic data was found. The described indirect method, relying purely on magneto-elastics, introduces a new path to the creation or alteration of magnetic properties subsequent to magnetic film preparation in structured magnetic samples without introducing any structural changes to the ferromagnetic layers. more...
- Published
- 2009
497. Local stress engineering of magnetic anisotropy in soft magnetic thin films
- Author
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Martin, N., McCord, J., Gerber, A., Strache, T., Gemming, T., Mönch, I., Farag, N., Schäfer, R., (0000-0003-3893-9630) Fassbender, J., Quandt, E., Schultz, L., Martin, N., McCord, J., Gerber, A., Strache, T., Gemming, T., Mönch, I., Farag, N., Schäfer, R., (0000-0003-3893-9630) Fassbender, J., Quandt, E., and Schultz, L. more...
- Abstract
The magnetic anisotropy of amorphous thin films was modified laterally by masked ion irradiation without alteration of the intrinsic magnetic properties. The changes were introduced by local ion implantation in a protection layer, causing additional stress-induced magnetic anisotropy in the magnetostrictive layer. The underlying local variation of magnetic anisotropy was modelled and confirmed experimentally. The described method, relying purely on magneto-elastics, introduces a new path to the alteration of magnetic properties subsequent to magnetic film preparation. With the use of the resulting artificial magnetization patterns it is possible to tailor the ferromagnetic thin film structure used in magneto-electronic applications. more...
- Published
- 2009
498. Local setting of magnetic anisotropy in FeCoSiB thin films by means of indirect ion implantation
- Author
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Martin, N., McCord, J., Gerber, A., Strache, T., Gemming, T., Mönch, I., Schäfer, R., (0000-0003-3893-9630) Fassbender, J., Quandt, E., Schultz, L., Martin, N., McCord, J., Gerber, A., Strache, T., Gemming, T., Mönch, I., Schäfer, R., (0000-0003-3893-9630) Fassbender, J., Quandt, E., and Schultz, L. more...
- Abstract
The magnetic anisotropy direction and strength of amorphous FeCoSiB thin films was modified locally by masked ion implantation without alteration of the magnetic materials structure and the intrinsic magnetic properties of the ferromagnetic film. The changes were introduced by local ion implantation in a SiO2 covering and protection layer, inducing additional stress-induced magnetic anisotropy to the magnetostrictive ferromagnetic layer. Hybrid hysteresis curves combining switching and rotational processes were measured and the underlying local variation of magnetic anisotropy was confirmed by magnetic domain observations. A good agreement between the calculated stress distribution and the experimentally obtained magnetic data was found. The described indirect method, relying purely on magneto-elastics, introduces a new path to the creation or alteration of magnetic properties subsequent to magnetic film preparation in structured magnetic samples without introducing any structural changes to the ferromagnetic layers. more...
- Published
- 2009
499. Removal of carbon films by oxidation in narrow gaps: Thermo-oxidation and plasma-assisted studies
- Author
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Tanarro, Isabel, Ferreira, J. A., Herrero, Víctor J., Tabarés, Francisco L., Gómez-Aleixandre, C., Tanarro, Isabel, Ferreira, J. A., Herrero, Víctor J., Tabarés, Francisco L., and Gómez-Aleixandre, C. more...
- Abstract
The removal of hard amorphous hydrogenated carbon (a-C: H) films from narrow gaps simulating the macro-brush structures present in controlled fusion devices has been investigated. Films with thickness of 50-150 nm were generated through plasma assisted chemical vapor deposition (PACVD) in glow discharges of CH4/He on Si and stainless steel plates. The deposited plates were then arranged to form sandwich structures building narrow gaps and were subject to erosion by exposure to O2/He plasmas and to thermal oxidation by O2 and by a NO2/N2 (1:1) mixture. In the plasma etching experiments, the deposited layers were only partially removed by the plasma at the side wall gap surfaces, but were efficiently removed at the bottom of the gap. In the thermo-oxidation experiments, the deposited films were effectively and homogeneously removed with oxigen at 670 K and with the NO2/N2 mixture at T > 570 K. more...
- Published
- 2009
500. Modification of Atomic Structure of Thin Amorphous V2O 5 Films under UV Laser Irradiation
- Author
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Cheremisin, A. B., Loginova, S. V., Velichko, A. A., Putrolaynen, V. V., Pergament, A. L., Grishin, Alexander, Cheremisin, A. B., Loginova, S. V., Velichko, A. A., Putrolaynen, V. V., Pergament, A. L., and Grishin, Alexander more...
- Abstract
Influence of ultra-violet radiation of the KrF laser (wave length 248 nm, pulse duration 20 ns) on atomic structure of amorphous vanadium pentoxide thin films, prepared by the pulsed laser deposition method, is studied. Calculations of the short-range order characteristics (radii and diffusiveness of coordination spheres, coordination numbers) were performed by the Finbak -Warren method. It is established that minimal structure unit of amorphous V 2O5 film before and after irradiation is a strongly deformed oxygen octahedron. Distortions of tetragonal pyramids in the initial and modified film are different. Also, oxygen deficiency in a tetragonal pyramid is observed., QC 20141015 more...
- Published
- 2008
- Full Text
- View/download PDF
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