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Book Chemical Vapor Deposition of Group IVB VB and VIB Elements with Nonmetals

Download or read book Chemical Vapor Deposition of Group IVB VB and VIB Elements with Nonmetals written by Hector O. McDonald and published by . This book was released on 1983 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Information Circular

Download or read book Information Circular written by United States. Bureau of Mines and published by . This book was released on 1983 with total page 754 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Information Circular

Download or read book Information Circular written by and published by . This book was released on 1983 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Spectroscopic Structural and Electrical Characterization of Thin Films Vapor deposited from the Spin crossover Complex Fe phen 2 NCS 2

Download or read book Spectroscopic Structural and Electrical Characterization of Thin Films Vapor deposited from the Spin crossover Complex Fe phen 2 NCS 2 written by Edward Ellingsworth and published by . This book was released on 2015 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin films (~100 nm) have been prepared of the prototypical spin-crossover complex Fe(phen)2(NCS)2 (phen = 1,10-phenanthroline). Initial attempts to prepare these films by direct vapor deposition yielded films of a different material. Through extensive FT-IR, Raman, UV-Vis, and x-ray photoelectron spectroscopy it is shown that these as-deposited films are the ferroin-based tris complex [Fe(phen)3](SCN)2. Structural characterization by AFM and powder XRD reveals them to be smooth and amorphous. When heated, the [Fe(phen)3](SCN)2 films are converted first to Fe(phen)2(SCN)2 and then to a third species postulated to be Fe(phen)(NCS)2 which is likely a one-dimensional coordination polymer. On the other hand, deposition from Fe(phen)2(NCS)2 onto heated substrates produces a mixture of these three materials. The identity of the Fe(phen)2(NCS)2 films is proved by additional spectroscopic, structural, and magnetic characterization. Magnetometry reveals them to remain spin-crossover active albeit with a more gradual and incomplete spin-transition than the bulk material. The films are found to be granular in nature and deep crevices were observed at the grain boundaries. Within the optical microscope, the coloring of the grains is seen to be dependent upon sample orientation. Powder XRD indicates texturing of crystalline domains where the crystallographic c-axis is parallel to the surface normal. This represents a new process for production of Fe(phen)2(NCS)2 films. With the aim of realizing the potential for spin-crossover materials to modulate electrical conduction and vise versa, electrical characterization has been performed as a function of temperature on vertical junction devices incorporating the prepared Fe(phen)2(NCS)2 films. In order to prevent penetration of the top electrode through the cracks and crevices in the organometallic layer, a multiple sequential deposition and annealing process was developed to produce films with a continuous surface topography. A small change in the weak electrical conductivity of these devices appears at the spin transition temperature, demonstrating for the first time in this important material a coupling of the electrical conductivity and magnetic spin state. Here, the HS state has a higher electrical conductivity. Incorporation of LiF interfacial layers between the Fe(phen)2(NCS)2 and the metal electrodes improves conduction slightly but tunneling still appears to be the current-limiting mechanism. Electrical measurements were also performed on devices made with the related complex [Fe(phen)3](SCN)2. Such films were much more conductive - as good as other typical organic semiconductor materials. All together, this work establishes the potential for this family of complexes to be incorporated into thin-film based electrical devices whose operation is based on the spin-crossover effect or otherwise.

Book Physical vapor deposition and thermal stability of hard oxide coatings

Download or read book Physical vapor deposition and thermal stability of hard oxide coatings written by Ludvig Landälv and published by Linköping University Electronic Press. This book was released on 2019-04-26 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: The state-of-the-art tools for machining metals are primarily based on a metal-ceramic composite (WC-Co) coated with different combinations of carbide, nitride, and oxide coatings. Combinations of these coating materials are optimized to withstand specific wear conditions. Oxide coatings, mainly α-Al2O3, are especially desired because of their high hot-hardness, chemical inertness with respect to the workpiece, and their low friction. The search for possible alloy elements, which may facilitate the deposition of such oxides by means of physical vapor deposition (PVD) techniques, has been the goal of this thesis. The sought alloy should form thermodynamically stable or metastable compounds, compatible with the temperature of use in metal cutting application. This thesis deals with process development and coating characterization of such new oxide alloy thin films, focusing on the Al-V-O, Al-Cr-Si-O, and Cr-Zr-O systems. Alloying aluminum oxide with iso-valent vanadium is a candidate for forming the desired alloys. Therefore, coatings of (Al1-xVx)2O3, with x ranging from 0 to 1, were deposited with reactive sputter deposition. X-ray diffraction showed three different crystal structures depending on V-metal fraction in the coating: α-V2O3 rhombohedral structure for 100 at.% V, a defect spinel structure for the intermediate region, (63 - 42 at.% V), and a gamma-alumina-like solid solution at lower V-content, (18 and 7 at.%), were observed, the later was shifted to larger d-spacing compared to the pure γ-Al2O3 sample obtained if deposited with only Al-target. Annealing the Al-rich coatings in air resulted in formation of V2O5 crystals on the surface of the coating after annealing to 500 °C for 42 at.% V and 700 °C for 18 at.% V metal fraction respectively. The highest thermal stability was shown for pure γ-Al2O3-coating which transformed to α-Al2O3 after annealing to 1100° C. Highest hardness was observed for the Al-rich oxides, ~24 GPa. The hardness then decreases with increasing V-content, larger than 7 at.% V metal fraction. Doping the Al2O3 coating with 7 at.% V resulted in a significant surface smoothening compared to the binary oxide. The measured hardness after annealing in air decreased in conjunction with the onset of further oxidation of the coatings. This work increases the understanding of this complicated material system with respect to possible phases formed with pulsed DC magnetron sputtering deposition as well as their response to annealing in air. The inherent difficulties of depositing insulating oxide films with PVD, requiring a closed electrical circuit, makes the investigation of process stability an important part of this research. In this context, I investigated the influence of adding small amount of Si in Al-Cr cathode on the coating properties in a pulsed DC industrial cathodic arc system and the plasma characteristics, process parameters, and coating properties in a lab DC cathodic arc system. Si was chosen here due to a previous study showing improved erosion behavior of Al-Cr-Si over pure Al-Cr cathode without Si incorporation in the coating. The effect of Si in the Al-Cr cathode in the industrial cathodic arc system showed slight improvements on the cathode erosion but Si was found in all coatings where Si was added in the cathode. The Si addition promoted the formation of the B1-like metastable cubic oxide phase and the incorporation led to reduced or equal hardness values compared to the corresponding Si-free processes. The DC-arc plasma study on the same material system showed only small improvements in the cathode erosion and process stability (lower pressure and cathode voltage) when introducing 5 at.% Si in the Al70Cr30-cathode. The presence of volatile SiO species could be confirmed through plasma analysis, but the loss of Si through these species was negligible, since the coating composition matched the cathode composition also under these conditions. The positive effect of added Si on the process stability at the cathode surface, should be weighed against Si incorporation in the coating. This incorporation seems to lead to a reduction in mechanical properties in the as-deposited coatings and promote the formation of a B1-like cubic metastable oxide structure for the (Al,Cr)2O3 oxide. This formation may or may not be beneficial for the final application since literature indicates a slight stabilization of the metastable phase upon Si-incorporation, contrary to the effect of Cr, which stabilizes the α-phase. The thermal stability of alloys for metal cutting application is crucial for their use. Previous studies on another alloy system, Cr-Zr-O, had shown solid solution, for Cr-rich compositions in that material system, in the sought corundum structure. The thermal stability of α-Cr0.28Zr0.10O0.61 coating deposited by reactive radio frequency (RF)-magnetron sputtering at 500 °C was therefore investigated here after annealing in vacuum up to 870 °C. The annealed samples showed transformation of α-(Cr,Zr)2O3 and amorphous ZrOx-rich areas into tetragonal ZrO2 and bcc-Cr. The instability of the α-(Cr,Zr)2O3 is surprising and possibly related to the annealing being done under vacuum, facilitating the loss of oxygen. Further in situ synchrotron XRD annealing studies on the α-Cr0.28Zr0.10O0.61 coating in air and in vacuum showed increased stability for the air annealed sample up to at least 975 °C, accompanied with a slight increase in ex-situ measured nanohardness. The onset temperature for formation of tetragonal ZrO2 was similar to that for isothermally vacuum annealing. The synchrotron-vacuum annealed coating again decomposed into bcc-Cr and t-ZrO2, with an addition of monoclinic–ZrO2 due to grain growth. The stabilization of the room temperature metastable tetragonal ZrO2 phase, due to surface energy effects present with small grains sizes, may prove to be useful for metal cutting applications. The observed phase segregation of α-(Cr,Zr)2O3 and formation of tetragonal ZrO2 with corresponding increase in hardness for this pseudobinary oxide system also opens up design routes for pseudobinary oxides with tunable microstructural and mechanical properties.

Book Thin Films by Chemical Vapour Deposition

Download or read book Thin Films by Chemical Vapour Deposition written by C. E. Moroșanu and published by . This book was released on 1990 with total page 724 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Noncrystalline Semiconductors

Download or read book Noncrystalline Semiconductors written by and published by . This book was released on 1987 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Electrochromic Properties of Vanadium Pentoxide Nanostructured Thin Films

Download or read book Electrochromic Properties of Vanadium Pentoxide Nanostructured Thin Films written by Afaf Almoabadi and published by . This book was released on 2015 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT Electrochromic Properties of Vanadium Pentoxide Nanostructured Thin Films Afaf Almoabadi The focus of this work is the improvement of the electrochromic properties of vanadium pentoxide thin films in order to expand its use. Indeed, because of its rather poor electrochromic properties, until now, vanadium pentoxide has only been used as a storage material in an electrochromic device, in conjunction with tungsten oxide, molybdenum oxide etc. To this purpose, vanadium pentoxide thin films were prepared under different conditions and characterized by using optical and electrochemical methods. Films were deposited on indium tin oxide (ITO) substrates by dip-coating at both room- and sub-zero temperature (-100C) and porosity in the sol-gel prepared vanadium pentoxide film was created by using templating methods. The morphology, optical and electrochromic properties of the macro- and mesoporous films, prepared in the presence of structure-directing agents such as polystyrene microspheres and triblock copolymer, have been compared with those of dense films. By using various methods to remove the template material, it was shown that the morphology of the vanadium pentoxide film can be controlled and new nanostructures can be created. The transformation of the lamellar into a nanorod structure, observed when the film is heated at 425-500◦C for several hours, resulted in the development of an elegant method for the synthesis of vanadium oxide nanostructures. The electrochromic performance of the nanorods prepared through the thermal treatment was found to be superior to that of the vanadium pentoxide with the layered structure, especially in the near-infrared region, demonstrating their potential for electrochromic applications. The structure, morphology, optical and electrochromic properties of dense and porous vanadium oxide films, coated at low temperature were also determined and compared to those of the corresponding films, deposited under room-temperature conditions. The results indicated that in the films coated at -100C, a residual compressive stress exists that originates from a non-uniformity in depth of the film, most probably, due to the formation of micro voids during the deposition. The micro voids are preserved during the heat-treatment of the films. The "micro void" morphology was found to account for the considerably improved electrochromic properties of the sub-zero dip-coated films. Low-temperature coated films, heated at 4500C for several hours, undergo the transformation from a layered to a highly uniform nanorod structure with important potential optoelectronic applications. The overall aim of this work is thus to evaluate how the morphology of vanadium pentoxide thin films is instrumental in obtaining a material with a high lithium ion intercalation capacity. With an appropriate morphology, the performance of vanadium oxide as electrochromic material and as cathode in lithium ion batteries can be improved significantly. For this purpose, both layered (dense and porous) and nanorod films were prepared and characterized. Scanning electron microscopy, cyclic voltammetry and electrical impedance spectroscopy measurements were used for the characterization of the different V2O5 films.

Book Physics Briefs

Download or read book Physics Briefs written by and published by . This book was released on 1993 with total page 1058 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book The Structural and Optical Properties of Hydrogenated Amorphous Carbon a C H Thin Films Deposited Using a Direct Current plasma Enhanced Chemical Vapour Deposition DC PECVD Technique

Download or read book The Structural and Optical Properties of Hydrogenated Amorphous Carbon a C H Thin Films Deposited Using a Direct Current plasma Enhanced Chemical Vapour Deposition DC PECVD Technique written by Suriani Abu Bakar and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Structural and Optical Properties of Amorphous AsxSe100 x Films Prepared by Plasma enhanced Chemical Vapour Deposition

Download or read book Structural and Optical Properties of Amorphous AsxSe100 x Films Prepared by Plasma enhanced Chemical Vapour Deposition written by Robert Callaerts and published by . This book was released on 2000 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book INIS Atomindex

Download or read book INIS Atomindex written by and published by . This book was released on 1995 with total page 682 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Acta Physica Academiae Scientiarum Hungaricae

Download or read book Acta Physica Academiae Scientiarum Hungaricae written by and published by . This book was released on 1980 with total page 470 pages. Available in PDF, EPUB and Kindle. Book excerpt: