Journal articles: 'Rutile. Thin films. Metallic oxides'

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Jeong, Jaewoo, Nagaphani B. Aetukuri, Donata Passarello, Steven D. Conradson, Mahesh G. Samant, and Stuart S. P. Parkin. "Giant reversible, facet-dependent, structural changes in a correlated-electron insulator induced by ionic liquid gating." Proceedings of the National Academy of Sciences 112, no. 4 (January 12, 2015): 1013–18. http://dx.doi.org/10.1073/pnas.1419051112.

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The use of electric fields to alter the conductivity of correlated electron oxides is a powerful tool to probe their fundamental nature as well as for the possibility of developing novel electronic devices. Vanadium dioxide (VO2) is an archetypical correlated electron system that displays a temperature-controlled insulating to metal phase transition near room temperature. Recently, ionic liquid gating, which allows for very high electric fields, has been shown to induce a metallic state to low temperatures in the insulating phase of epitaxially grown thin films of VO2. Surprisingly, the entire film becomes electrically conducting. Here, we show, from in situ synchrotron X-ray diffraction and absorption experiments, that the whole film undergoes giant, structural changes on gating in which the lattice expands by up to ∼3% near room temperature, in contrast to the 10 times smaller (∼0.3%) contraction when the system is thermally metallized. Remarkably, these structural changes are fully reversible on reverse gating. Moreover, we find these structural changes and the concomitant metallization are highly dependent on the VO2 crystal facet, which we relate to the ease of electric-field–induced motion of oxygen ions along chains of edge-sharing VO6 octahedra that exist along the (rutile) c axis.

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Lee, Han-Seung, Jin-ho Park, Jitendra Kumar Singh, and Mohamed A. Ismail. "Deposition of Coating to Protect Waste Water Reservoir in Acidic Solution by Arc Thermal Spray Process." Advances in Materials Science and Engineering 2018 (2018): 1–13. http://dx.doi.org/10.1155/2018/4050175.

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The corrosion characteristics of 304 stainless steel (SS) and titanium (Ti) coatings deposited by the arc thermal spray process in pH 4 solution were assessed. The Ti-sprayed coating exhibits uniform, less porous, and adherent coating morphology compared to the SS-sprayed coating. The electrochemical study, that is, electrochemical impedance spectroscopy (EIS), revealed that as exposure periods to solution were increased, the polarization resistance (Rp) decreased and the charge transfer resistance (Rct) increased owing to corrosion of the metallic surface and simultaneously at the same time the deposition of oxide films/corrosion on the SS-sprayed surface, while Ti coating transformed unstable oxides into the stable phase. Potentiodynamic studies confirmed that both sprayed coatings exhibited passive tendency attributed due to the deposition of corrosion products on SS samples, whereas the Ti-sprayed sample formed passive oxide films. The Ti coating reduced the corrosion rate by more than six times compared to the SS coating after 312 h of exposure to sulfuric acid- (H2SO4-) contaminated water solution, that is, pH 4. Scanning electron microscope (SEM) results confirmed the uniform and globular morphology of the passive film on the Ti coating resulting in reduced corrosion. On the other hand, the corrosion products formed on SS-sprayed coating exhibit micropores with a net-like microstructure. X-ray diffraction (XRD) revealed the presence of the composite oxide film on Ti-sprayed samples and lepidocrocite (γ-FeOOH) on the SS-coated surface. The transformation of TiO and Ti3O into TiO2 (rutile and anatase) and Ti3O5 after 312 h of exposure to H2SO4 acid reveals the improved corrosion resistance properties of Ti-sprayed coating.

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Kaczmarek, Danuta, Jaroslaw Domaradzki, Damian Wojcieszak, Eugeniusz Prociow, Michal Mazur, Frank Placido, and Steffen Lapp. "Hardness of Nanocrystalline TiO₂ Thin Films." Journal of Nano Research 18-19 (July 2012): 195–200. http://dx.doi.org/10.4028/www.scientific.net/jnanor.18-19.195.

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In this work results of hardness investigations of nanocrystalline TiO2 thin films are presented. Thin films were prepared by low pressure hot target reactive sputtering (LPHTRS) and high energy reactive magnetron sputtering (HERMS). In both processes a metallic Ti target was sputtered under low pressure of oxygen working gas. After deposition by LPHTRS TiO2 thin films with anatase structure were obtained and after additional post-process annealing at 1070 K, these films recrystallized into the rutile structure. Annealing also resulted in an increase of average crystallite size from 33 nm (for anatase) to 74 nm (for rutile). The HERMS process is a modification of the LPHTRS process with the addition of an increased amplitude of unipolar voltage pulses, powering the magnetron. This effectively increases the total energy of the depositing particles at the substrate and allows dense, nanocrystalline (8.7 nm crystallites in size) TiO2 thin film with the rutile structure to be formed directly. The hardness of the films was determined by nanoindentation. The results showed that the nanocrystalline TiO2-rutile thin film as-deposited using HERMS had high hardness (14.3 GPa), while the TiO2-anatase films as-deposited by LPHTRS, were 4-times lower (3.5 GPa). For LPHTRS films recrystallized by additional annealing, the change in thin film structure from anatase to rutile resulted in an increase of film hardness from 3.5 GPa to only 7.9 GPa. The HERMS process can therefore produce the TiO2 rutile structure directly, with hardness that is 2 times greater than rutile films produced by LPHTRS with additional annealing step.

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Asano, Hidefumi, Norihito Koduka, Mikito Sugiyama, and Masaaki Matsui. "Growth and Properties of Half-Metallic Double Perovskite Thin Films." Materials Science Forum 475-479 (January 2005): 2197–202. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.2197.

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Ferromagnetic oxides with ordered double-perovskites Sr2FeMoO6 and Sr2CrReO6 are known to be in a half-metallic ground state with high Curie temperatures Tc, and hence one of the promising materials for spin electronics. This paper reports epitaxial growth and micro-structural, magnetic, and electrical characterization of thin films of these oxides. It is shown that a coherent growth without strain relaxation, which is accomplished by the use of substrate or buffer layers with a small (0.1%) lattice match, is essential to obtain high quality films with both atomically flat surface and high magnetization values expected for their half-metallicity

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Uttiya, Sureeporn, Ornella Cavalleri, Michele Biasotti, Marcella Pani, Maria Maddalena Carnasciali, Daniele Caviglia, Lorenzo Mattera, and Maurizio Canepa. "Mesoporous Titanium Dioxide Thin Films on Quartz via Electrochemical Anodisation Process." Advanced Materials Research 1119 (July 2015): 456–60. http://dx.doi.org/10.4028/www.scientific.net/amr.1119.456.

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Titanium dioxide (TiO2) thin films were prepared by means of electrochemical anodisation or anodic spark deposition (ASD) from thin and flat metallic titanium (Ti) films pre-deposited on high quality quartz substrates by electron beam evaporation. AFM analysis indicates the formation of uniform mesoporous layers and a definite increase about 50% of the film thickness upon anodisation and about 90% upon annealing. Anodised mesoporous TiO2films have been characterized by Raman spectroscopy, which indicates the presence of well-defined peaks related to anatase structure. Phase transformation from anatase to rutile was observed after annealing at temperatures up to 900°C for 3h.

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Guo, Q., S. Lee, and D. W. Goodman. "Vanadium oxides thin films grown on rutile TiO2(110)-(1×1) and (1×2) surfaces." Surface Science 437, no. 1-2 (August 1999): 38–48. http://dx.doi.org/10.1016/s0039-6028(99)00674-3.

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Unal, Ugur, Dan Matsuo, Yasumichi Matsumoto, and Michio Koinuma. "Thermally-induced phase changes in electrophoretically deposited titanate and niobate layered oxides." Journal of Materials Research 17, no. 10 (October 2002): 2644–51. http://dx.doi.org/10.1557/jmr.2002.0384.

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Thin films of CsxTi(2−x/4)□x/4O4 (CsTiO), K4Nb6O17 (KNbO), and their proton-exchanged forms, i.e., HxTi(2−x/4)□x/4O4 (HTiO) and H4Nb6O17 (HNbO), were prepared using the electrophoretic deposition technique. The amine- and thiol-intercalated HTiO and HNbO films were prepared by exfoliation of powders in aqueous ethylamine and (mercaptoethyl)amine hydrochloride solutions, respectively. The heat-induced phase transformation of these films was investigated. Evidently, the CsTiO and thiol-intercalated HTiO films underwent phase transformation at relatively high temperatures due to the cations within the interlayer. CsTiO and HTiO films lost their layered structure and transformed, in turn, into the anatase and rutile phases with increasing temperature. However, the intercalated samples exhibited unidentified phases at in-between temperatures, eventually transforming to TiO2. The KNbO film transformed into a layered KNb3O8 structure, while the HNbO lost its layered structure completely to form Nb2O5. Thus, the phase change depended on the modification of the interlayers, and the heat treatment resulted in thin films with new crystal structures for the amine- and thiol-intercalated samples.

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Becker, Martin, Angelika Polity, Davar Feili, and Bruno K. Meyer. "Deposition of tin oxides by Ion-Beam-Sputtering." MRS Proceedings 1494 (2012): 153–58. http://dx.doi.org/10.1557/opl.2012.1650.

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ABSTRACTSynthesis of both p-type and n-type oxide semiconductors is required to develop oxide-based electronic devices. Tin monoxide (SnO) recently has received increasing attention as an alternative p-type oxide semiconductor because it is a simple binary compound consisting of abundant elements. Another phase of the tin oxygen system, SnO2, is of great technological interest as transparent electrodes and as heat-reflecting filters. The preparation of tin oxide thin films has been performed by many different procedures. Radio-frequency (RF) ion-thrusters, as designed for propulsion applications, are also qualified for thin film deposition and surface etching, because different gas mixtures, extraction voltages and RF power can be applied. Tin oxide thin films were grown by ion beam sputtering (IBS) using a 3” metallic tin target. Different aspects of the thin film growth and properties of the tin oxide phases were investigated in relation to flux of oxygen fed into the gas discharge in the ion thruster. Results on thin film growth by IBS will be presented, structural, vibrational and optical properties of the films will be discussed.

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Vook, R. W., T. V. Rao, T. Swirbel, J. Bucci, and W. Meyer. "Thin films for radiation control in boiling water nuclear reactors." Proceedings, annual meeting, Electron Microscopy Society of America 44 (August 1986): 520–21. http://dx.doi.org/10.1017/s0424820100144115.

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Boiling water nuclear reactors (BWR's) experience radioactive film buildup on the inner walls of their out-of-core stainless steel (S.S.) cooling water pipes. These films consist of various oxides of Fe, Cr, and Ni, and contain small amounts of radioactive Co-60. As a result the pipes must be decontaminated or replaced periodically. Efforts are currently being made to passivate these S.S. surfaces so as to reduce the rate of radiation buildup. In the present work, the effects of various protective metallic thin film coatings on the morphology of the radioactive oxide film grown in a simulated BWR test loop are reported.

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Mazur, Michal, Danuta Kaczmarek, Eugeniusz Prociow, Jaroslaw Domaradzki, Damian Wojcieszak, and Jakub Bocheński. "Investigation of structural, optical and electrical properties of (Ti,Nb)Ox thin films deposited by high energy reactive magnetron sputtering." Materials Science-Poland 32, no. 3 (September 1, 2014): 457–64. http://dx.doi.org/10.2478/s13536-013-0195-4.

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AbstractIn this work the results of investigations of the titanium-niobium oxides thin films have been reported. The thin films were manufactured with the aid of a modified reactive magnetron sputtering process. The aim of the research was the analysis of structural, optical and electrical properties of the deposited thin films. Additionally, the influence of post-process annealing on the properties of studied coatings has been presented. The as-deposited coatings were amorphous, while annealing at 873 K caused a structural change to the mixture of TiO2 anatase-rutile phases. The prepared thin films exhibited good transparency with transmission level of ca. 50 % and low resistivity varying from 2 Ωcm to 5×10−2 Ωcm, depending on the time and temperature of annealing. What is worth to emphasize, the sign of Seebeck coefficient changed after the annealing process from the electron to hole type electrical conduction.

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Witit-Anun, N., P. Rakkwamsuk, and Pichet Limsuwan. "Characterization of Anatase and Rutile TiO₂Thin Films Deposited by Two Cathodes Sputtering System." Advanced Materials Research 55-57 (August 2008): 469–72. http://dx.doi.org/10.4028/www.scientific.net/amr.55-57.469.

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Titanium dioxide, TiO2, thin films were deposited on unheated Si (100) wafers by two cathodes sputtering system. However, during the deposition of TiO2 films only one cathode was used. A pure metallic titanium was used as a sputtering target. Argon and oxygen were used as sputtered gas and reactive gas, respectively. TiO2 films were deposited at the argon and oxygen ratio of 1:4 and a total pressure of 5.0 x 10-3 mbar. The distance between the target and the center point of substrate was 12 cm. For each deposition of TiO2 films, the position of substrate was changed every 2 cm on the radial position of the cathode. The deposition time for each deposition was 60 min. The films were characterized by X-ray diffraction (XRD) technique and transmission electron microscopy (TEM). The XRD results and TEM images show that the crystalline rutile TiO2 films can be successfully deposited on an unheated substrate.

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HUANG, D. J., L. H. TJENG, J. CHEN, C. F. CHANG, W. P. WU, A. D. RATA, T. HIBMA, et al. "ELECTRON CORRELATION EFFECTS IN HALF-METALLIC TRANSITION METAL OXIDES." Surface Review and Letters 09, no. 02 (April 2002): 1007–15. http://dx.doi.org/10.1142/s0218625x02001872.

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Spin-resolved photoemission and absorption studies of Fe 3 O 4 and CrO 2 epitaxial thin films have been reviewed to address the relationship between the electron correlation effects and the half-metallic properties of these two materials. Spin-resolved photoemission results suggest that Fe 3 O 4 should be considered as a strongly correlated system, and that Fe 3 O 4 is not a half-metal. Spin-resolved O 1s X-ray absorption measurements on ferromagnetic CrO 2 reveal that the spin polarization of the unoccupied states closest to the Fermi level approaches 100%, confirming the half-metallic ferromagnetic nature of the material. The spin polarization of the main line of the unoccupied states, on the other hand, is found to be only 50%, indicating a very atomic-like behavior of the Cr 3d2 ions.

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Czerwinski, F., and J. A. Szpunar. "Texture in Metallic and Ceramic Films and Coatings." Textures and Microstructures 32, no. 1-4 (January 1, 1999): 107–18. http://dx.doi.org/10.1155/tsm.32.107.

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The properties of films and coatings can be optimized for a variety of applications by modifying their texture. Understanding how the texture in thin films is formed and how it can be controlled during film growth process is one of the most important areas of texture research. Several examples were selected to illustrate how the texture in films and coatings is developed and to explain how various properties of films are affected by texture. In particular, texture development during electrodeposition of Zn-based automobile coatings, Ni and Ni-based layers for magnetic recording as well as Fe and Fe-based wearresistant coatings, is presented. A new area of application of texture research to control the high-temperature oxidation resistance of engineering materials is described. Using experimental data for Ni and Ti, the factors affecting texture formation during growth of ceramic oxides are discussed, with special attention paid to the role of substrate texture. The correlation between the oxide texture, grain boundary structure and diffusion of metal and oxygen ions at high temperatures, is considered.

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Zavadil, K. R., N. R. Armstrong, and C. H. F. Peden. "Reactions at the interface between multi-component glasses and metallic lithium films." Journal of Materials Research 4, no. 4 (August 1989): 978–89. http://dx.doi.org/10.1557/jmr.1989.0978.

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The reactions of vacuum deposited thin films of lithium with various complex glasses have been explored using x-ray photoelectron spectroscopy (XPS). In contrast to lithium reactions with simple glasses such as silica or boron oxides, the reactions are predominantly those of the network modifiers such as sodium, potassium, and magnesium. XPS and x-ray induced Auger lineshapes indicate the migration of the network modifier to the near surface region followed by its reduction. In the case of magnesium, there is evidence for stable alloy formation with unreacted lithium following these migration and reduction steps.

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TIT, NACIR, J. W. HALLEY, and H. B. SHORE. "INVARIANCE OF THE MOBILITY EDGE IN ANODIC TITANIUM OXIDES." International Journal of Modern Physics B 07, no. 01n03 (January 1993): 361–64. http://dx.doi.org/10.1142/s0217979293000767.

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We present a theoretical investigation to explain the electronic and optical properties of anodic rutile TiO2 thin films of different thicknesses (ranging from 5nm to 20nm). There is experimental evidence that the observed gap state at 0.7eV below the edge of conduction-band is due to an oxygen vacancy. For this reason, oxygen vacancies are used as defects in our model. A comparison of the calculated bulk-photoconductivity to photospectroscopy experiment reveals that the films have bulk-like transport properties with a bandgap Eg = 3.0eV. On the other hand, a fit of the surface density of states to the scanning tunneling microscopy (STM) experiment on the (001) surfaces has suggested a surface defect density of 5% of oxygen vacancies. To resolve this discrepancy, we calculated the dc-conductivity where localization effects are included. Our results show an impurity band formation at about pc = 9% of oxygen vacancies. We concluded that the studied films have defect densities below the threshold of impurity band formation. As a consequence the gap states seen in STM are localized (i.e: the oxygen vacancies are playing the role of trapping centers, deep levels) and the mobility edge is invariant.

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Rouxinol, F. Paulo, B. Cláudio Trasferetti, Richard Landers, and Mário A. Bica de Moraes. "Hot-filament metal oxide deposition (HFMOD): a novel method for depositing thin films of metallic oxides." Journal of the Brazilian Chemical Society 15, no. 2 (April 2004): 324–26. http://dx.doi.org/10.1590/s0103-50532004000200026.

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Shin, Woosuck, Akihiro Tsuruta, Toshio Itoh, Takafumi Akamatsu, and Ichiro Terasaki. "High Temperature Electrical Properties of Co-Substituted La4BaCu5O13+δ Thin Films Fabricated by Sputtering Method." Materials 14, no. 10 (May 20, 2021): 2685. http://dx.doi.org/10.3390/ma14102685.

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The high-temperature conductivity of the perovskite oxides of a La4BaCu5O13+δ (LBCO) thin film prepared by RF sputtering deposition and thermal annealing has been studied. While the bulk LBCO compound was metallic, the LBCO film deposited on a Si substrate by sputtering and a post annealing process showed semiconductor-like conduction, which is considered to be due to the defects and poor grain connectivity in the LBCO film on the Si substrate. The LBCO film deposited on a SrTiO3 substrate was of high film quality and showed metallic conduction. When the cation site Cu was substituted by Co, the electrical conductivity of the LBCO film increased further and its temperature dependence became smaller. The transport properties of LBCO films are investigated to understand its carrier generation mechanism.

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Bozovic, Ivan, and J. N. Eckstein. "Analysis of Growing Films of Complex Oxides by RHEED." MRS Bulletin 20, no. 5 (May 1995): 32–38. http://dx.doi.org/10.1557/s0883769400044870.

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The majority of sophisticated ultra-high-vacuum (UHV) systems for deposition of thin films, such as molecular beam epitaxy (MBE) machines, contain some kind of electron diffraction apparatus which is used to scrutinize the surface structure of the film while it is grown. Reflection high energy electron diffraction (RHEED) is probably the most frequently employed configuration. An excellent introduction to RHEED, including a treatment of electron diffraction, reciprocal-space description, reflection from imperfect surfaces, etc., was recently published in the MRS Bulletin by Lagally and Savage. Hence, we will not review these basics here. Rather, we will assume the reader to be familiar with that article, and will refer to it as LS.The materials discussed in LS include Si, Ge on Si, and GaAs. The applications of MBE for synthesis of semiconductor thin films and heterostructures are widely recognized. MRS has recently bestowed its greatest honor, the Von Hippel Award, to Alfred Y. Cho for his pioneering work on MBE synthesis of GaAs and its application to new devices.In contrast, here we focus on complex oxides—cuprates, titanates, manganates, etc. This is a relatively new area of application for both MBE and RHEED. Actually, it was only after the discovery of high-temperature superconductivity (HTS) that many MBE systems were designed and built specifically for metallic oxide deposition. More recently, some of these machines have also been employed to synthesize other interesting oxides, for example, ferroelectrics and ferromagnets. In all these studies, RHEED has been the principal diagnostic tool and source of information about the growing film surface.

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Kohno, H., T. Arai, Y. Araki, and R. Wilson. "High Accuracy Analysis of BPSG Thin Films on Silicon Wafers by X-Ray Wafer Analyzer." Advances in X-ray Analysis 37 (1993): 229–34. http://dx.doi.org/10.1154/s0376030800015731.

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The wafer analyzer has been used to fulfil many applications needs in the semiconductor industry. The prominent features of the XRF method for the semiconductor industry are:analysis of many types of films, e.g., oxides, silicides and metallic alloys, and simultaneous analysis of film thickness and compositions.In the past, the analysis results of BPSG (Boron-doped Phospho-Silicate Glass) films, with thicknesses greater than 4000 Å, were reported. With the recent increased demand for larger scale and higher quality semiconductor devices (larger than 64 Mbit), more accurate analysis with high precision has been required.

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Eom, C. B., R. J. Cava, R. M. Fleming, J. M. Phillips, R. B. vanDover, J. H. Marshall, J. W. P. Hsu, J. J. Krajewski, and W. F. Peck. "Single-Crystal Epitaxial Thin Films of the Isotropic Metallic Oxides Sr1-xCaxRuO3 (0 le x le 1)." Science 258, no. 5089 (December 11, 1992): 1766–69. http://dx.doi.org/10.1126/science.258.5089.1766.

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Kanu, Sapna Shrestha, and Russell Binions. "Thin films for solar control applications." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 466, no. 2113 (October 9, 2009): 19–44. http://dx.doi.org/10.1098/rspa.2009.0259.

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The excessive use of heating systems in cold climates and air conditioning systems in hotter climates is resulting in the extensive use of electricity in order to maintain such systems. This in turn leads to the greater use of fossil fuels and higher emissions of carbon dioxide and other pollutant gases. The growing amount of carbon dioxide emissions is contributing to the problem of global warming, hence increasing the need for alternative technologies to heating and air conditioning systems. One such alternative is the production of thin films which can be used as window glazing coatings to construct ‘smart windows’. These windows have the greatest use within constant climates. In cold climates, windows with high solar transmittance and low thermal emittance are needed; this allows sunlight into the building to brighten the room but stops heat from escaping thus warming the room. In constantly hot climates, materials that are transparent in the visible region but reflective in the infrared, such as thin metallic coatings, can be used to ensure that the inside of the building remains cool. These solar control coatings, however, pose a problem in varying climates such as in northern and central Europe. For these cases, materials that have altering properties owing to external surroundings could be the solution. These ‘chromatic’ materials include several categories, such as photochromic glasses and polymers, thermochromic metal oxides and electrochromic materials. This review will begin with a discussion as to the chemistry behind the solar control coatings and chromic materials including ambient radiation and the ideal of a black-body object. It will then look in depth at each class of these chromic materials considering experimental results and theoretical insight as well as production techniques and applications.

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Mohammadi, M. R., Mohammad Ghorbani, and Derek J. Fray. "Influence of Secondary Oxide Phases on Microstructural and Gas Sensitive Properties of Nanostructured Titanium Dioxide Thin Films." Advanced Materials Research 47-50 (June 2008): 41–44. http://dx.doi.org/10.4028/www.scientific.net/amr.47-50.41.

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A systematic comparison of single and binary metal oxide TiO2, TiO2-Ga2O3, TiO2-Er2O3 and TiO2-Ta2O5 gas sensors with nanocrystalline and mesoporous microstructure, prepared by solgel route, was conducted. The gas sensitivity was increased by secondary phase introduction into TiO2 film via two mechanisms, firstly through the inhibition of anatase-to-rutile transformation, since the anatase phase accommodates larger amounts of adsorbed oxygen, and secondly through the retardation of grain growth, since the higher surface area provides more active sites for gas molecule adsorption. The binary metal oxides exhibited a remarkable response towards low concentrations of CO and NO2 gases at low operating temperature of 200°C, resulting in increasing thermal stability of sensing films as well as decreasing their power consumption. The calibration curves revealed that all sensors followed the power law ( B gas A S ] [ = ) (where S is sensor response, coefficients A and B are constants and [gas] is gas concentration). The response magnitude of the sensors obtained in this work is superior to TiO2-based sensors reported in previous studies.

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Abouarab, Hanan, Amal Kassry, and Iman El-Mahallawi. "Structural, Optical and Microstructural Properties of TiNi Thin Films before and after Oxidation." Key Engineering Materials 835 (March 2020): 193–99. http://dx.doi.org/10.4028/www.scientific.net/kem.835.193.

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The deposition of composites with tailored optical properties is investigated. This would employ structures consisting of combined metallic and oxides nature. A thin layer of TiNi is obtained by using RF magnetron sputtering on a stainless-steel substrate, followed by oxidation at 400°C and 800°C for four and one hours, respectively. The optical properties of the thin films were characterized by optical spectrophotometer, and Fourier Transform Infrared Spectroscopy (FTIR). The morphology, topography, and structure were studied by scanning electron microscope (SEM), atomic force microscope (AFM), and X-ray diffraction (XRD). The results show that TiO2 has been produced through the oxidation process of the sputter-deposited TiNi thin film at high oxidation temperature. The TiNi thin films showed a significant improvement in optical properties after oxidation, as the absorbance increased, and the emittance was reduced. This work introduces oxidized TiNi thin films as candidates for solar selective absorber.

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Pansila, P. Pungboon, Nirun Witit-Anun, and Surasing Chaiyakun. "Effect of Oxygen Partial Pressure on the Morphological Properties and the Photocatalytic Activities of Titania Thin Films on Unheated Substrates by Sputtering Deposition Method." Advanced Materials Research 770 (September 2013): 18–21. http://dx.doi.org/10.4028/www.scientific.net/amr.770.18.

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Titania (TiO2) thin films have been deposited using d.c. reactive unbalance magnetron sputtering on unheated substrate by various different oxygen partial pressures while working pressure and sputtering power were kept constant. A pure metallic titanium disk was used for sputtering target in atmospheric of the mixture gases between argon and oxygen. The X-ray diffraction (XRD) and atomic force microscopy (AFM) were used for characterization of characteristics structure and surface morphologies of the films, respectively. The optical transmission of the films were measured by spectrophotometer. The photocatalytic activities of the films were investigated from measurement of methylene blue degradation by using absorbance value after UV irradiation for 6 hr. The results show that the crystalline structures of the films showed the presence of single-anatase phase and mixed-anatase/rutile phase of TiO2 thin films. The surface morphology and photocatalytic activities of the films depend on oxygen partial pressure that grains size, surface roughness and thickness of the films were deceased when increasing oxygen partial pressure due to poisoning phenomenon and the high reactive gases. In addition, it was found that all TiO2 thin films were deposited by different oxygen partial pressure exhibit a good transparentness. Moreover, it was found that the TiO2 thin films deposited by used low oxygen partial pressure and single-anatase phase exhibited the best photocatalytic activity.

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Molina, J., C. Zúñiga, M. Moreno, W. Calleja, P. Rosales, R. Ambrosio, F. J. De la Hidalga, et al. "Physical and electrical characterization of TiO2 particles after high temperature processing and before and after ultraviolet irradiation." Canadian Journal of Physics 92, no. 7/8 (July 2014): 832–37. http://dx.doi.org/10.1139/cjp-2013-0603.

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In this work, rutile-phase TiO2 particles (r-TiO2, about 360 nm in size) are embedded within a silicon oxide matrix using different concentration ratios of r-TiO2 with respect to SiO2:H2O, so that suspensions of mixed TiO2:SiO2 oxides were obtained and analyzed. These TiO2:SiO2 suspensions were deposited on previously-cleaned crystalline silicon and quartz substrates so that thin films of TiO2:SiO2 were obtained. All films were then exposed to relatively high-temperature thermal treatments in nitrogen and different characterization techniques were used to determine their physical and electrical properties before and after ultraviolet (UV) irradiation. Before high thermal treatment, X-ray diffraction patterns show that the main diffraction peaks for the obtained TiO2:SiO2 films correspond to the crystalline phase of rutile-TiO2. Infrared analyses before and after thermal treatment show significant changes in the chemical bonding of the final films relative to the temperatures used during annealing. Also, UV–visible spectra provide a constant optical band gap for the films, independent of different TiO2 concentrations as expected. On the other hand, atomic-force microscopy measurements before and after UV irradiation show an appreciable difference in the grain size and surface morphology of the resulting TiO2:SiO2 oxides annealed at 1000 °C. Finally, photoelectrical I–V properties were obtained for all TiO2:SiO2 films by depositing ultrathin titanium stripes on top of the photoactive material and then, measuring the total current flowing through the metal electrode before and after UV irradiation. From these last measurements, a detectable increase in the I–V slope (lower resistance of the titanium stripe) is found for all samples during UV exposure, thus making this device to act as a simple photoresistor based on r-TiO2 particles.

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Vahl, Alexander, Salih Veziroglu, Bodo Henkel, Thomas Strunskus, Oleksandr Polonskyi, Oral Cenk Aktas, and Franz Faupel. "Pathways to Tailor Photocatalytic Performance of TiO2 Thin Films Deposited by Reactive Magnetron Sputtering." Materials 12, no. 17 (September 3, 2019): 2840. http://dx.doi.org/10.3390/ma12172840.

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TiO2 thin films are used extensively for a broad range of applications including environmental remediation, self-cleaning technologies (windows, building exteriors, and textiles), water splitting, antibacterial, and biomedical surfaces. While a broad range of methods such as wet-chemical synthesis techniques, chemical vapor deposition (CVD), and physical vapor deposition (PVD) have been developed for preparation of TiO2 thin films, PVD techniques allow a good control of the homogeneity and thickness as well as provide a good film adhesion. On the other hand, the choice of the PVD technique enormously influences the photocatalytic performance of the TiO2 layer to be deposited. Three important parameters play an important role on the photocatalytic performance of TiO2 thin films: first, the different pathways in crystallization (nucleation and growth); second, anatase/rutile formation; and third, surface area at the interface to the reactants. This study aims to provide a review regarding some strategies developed by our research group in recent years to improve the photocatalytic performance of TiO2 thin films. An innovative approach, which uses thermally induced nanocrack networks as an effective tool to enhance the photocatalytic performance of sputter deposited TiO2 thin films, is presented. Plasmonic and non-plasmonic enhancement of photocatalytic performance by decorating TiO2 thin films with metallic nanostructures are also briefly discussed by case studies. In addition to remediation applications, a new approach, which utilizes highly active photocatalytic TiO2 thin film for micro- and nanostructuring, is also presented.

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Portinha, Anibal, Vasco Teixeira, Joaquim Carneiro, Rachel Newton, and H. Fonseca. "Structural Characterization of Sputtered Composite Stabilized ZrO₂ Thin Films." Materials Science Forum 514-516 (May 2006): 1150–54. http://dx.doi.org/10.4028/www.scientific.net/msf.514-516.1150.

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Zirconia (ZrO2) exhibits three different polymorphic phases as a function of the thermal and pressure conditions (cubic, tetragonal and monoclinic). The use of zirconia coatings at high temperatures requires it to be stabilized at room temperature in order to maintain the high temperature phases when subjected to thermal cycles. For this purpose, this work reports different ways to stabilize ZrO2 coatings produced by DC reactive magnetron sputtering. We have produced stabilized ZrO2 coatings by doping with other metallic and rare earth oxides (Y2O3 and Gd2O3), depositing nanostructured ZrO2 crystallites in an amorphous Al2O3 matrix and using a ZrO2/Al2O3 nanolaminated structure. A comparative study of the coatings produced is presented along with their structural stabilization using different approaches. For the doped coatings the tetragonal or cubic phases were obtained as a function of the dopant percentage and for the nanostructured and nanolayered structures the stabilization mechanism is related to the constraining of the zirconia nanocrystallites and the capacity to maintain its size under certain value.

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Peng, Bin, Ren-Ci Peng, Yong-Qiang Zhang, Guohua Dong, Ziyao Zhou, Yuqing Zhou, Tao Li, et al. "Phase transition enhanced superior elasticity in freestanding single-crystalline multiferroic BiFeO3 membranes." Science Advances 6, no. 34 (August 2020): eaba5847. http://dx.doi.org/10.1126/sciadv.aba5847.

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The integration of ferroic oxide thin films into advanced flexible electronics will bring multifunctionality beyond organic and metallic materials. However, it is challenging to achieve high flexibility in single-crystalline ferroic oxides that is considerable to organic or metallic materials. Here, we demonstrate the superior flexibility of freestanding single-crystalline BiFeO3 membranes, which are typical multiferroic materials with multifunctionality. They can endure cyclic 180° folding and have good recoverability, with the maximum bending strain up to 5.42% during in situ bending under scanning electron microscopy, far beyond their bulk counterparts. Such superior elasticity mainly originates from reversible rhombohedral-tetragonal phase transition, as revealed by phase-field simulations. This study suggests a general fundamental mechanism for a variety of ferroic oxides to achieve high flexibility and to work as smart materials in flexible electronics.

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Mardare, Cezarina C., Michael Spiegel, Alan Savan, and Alfred Ludwig. "Investigation of Thin Coatings from Mn-Co-Fe System Deposited by PVD on Metallic Interconnects for SOFC Applications." Materials Science Forum 595-598 (September 2008): 797–804. http://dx.doi.org/10.4028/www.scientific.net/msf.595-598.797.

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Ternary Mn-Co-Fe metallic thin films were deposited by RF-magnetron co-sputtering on SiO2/Si wafers and on ZMG232L (Hitachi Metals®), a special ferritic stainless steel for Solid Oxide Fuel Cell applications. The deposition was followed by heat treatment in an oxidizing atmosphere in order to convert the metallic thin films to (Mn,Co,Fe)3O4 spinel oxides. Coated and uncoated steel samples were analyzed after 1 h heat treatment in order to confirm the presence of the spinel structure on top of the steel, as well as to investigate and characterize the growth of oxides, namely (Mn,Cr)3O4 and Cr2O3, at the internal steel/coating interface. From Grazing Incidence X-ray Diffraction (GI-XRD) investigations together with Energy Dispersive X-ray analysis – Scanning Electron Microscopy and Time of Flight – Secondary Ions Mass Spectroscopy sputtering depth profiling the presence of well adherent (Mn,Co,Fe)3O4 coatings with approximately 500 nm thickness and a grain size of about 150 nm was confirmed. After the preparation annealing, some samples were heat-treated in simulated cathodic atmospheres at 800 °C for 500 h in order to assess the stability of the coatings. GI-XRD spectra still showed the presence of the protective coatings, however sputtering depth profile analysis indicated the presence of Cr on the surface.

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30

Shirzadi, A. A., and E. R. Wallach. "Novel Method for Diffusion Bonding Superalloys and Aluminium Alloys (USA Patent 6,669,534 B2, European Patent Pending)." Materials Science Forum 502 (December 2005): 431–36. http://dx.doi.org/10.4028/www.scientific.net/msf.502.431.

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A novel method for diffusion bonding metallic alloys with stable surface oxide films (e.g. nickel and cobalt base superalloys and aluminium alloys) has been developed. The stable oxides on the faying surfaces of these alloys are replaced, prior to the bonding process, with a very thin metallic layer and/or less stable oxides, using a proprietary non-chemical oxide removal method based on the use of gallium. This new method is very rapid and neither requires the use of any sophisticated equipment nor is a costly process. Bonding is then readily achieved by either solid-state or transient-liquid-phase (TLP) diffusion bonding. Using this method, bonds in nickelbase and cobalt-base superalloys with “virtually invisible” bond interfaces and bonds in aluminium alloys with strengths as high as those of the parent alloys can be produced.

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Zhou, X. W., D. A. Murdick, B. Gillespie, J. J. Quan, Haydn N. G. Wadley, Ralf Drautz, and David Pettifor. "Atomic Assembly of Thin Film Materials." Materials Science Forum 539-543 (March 2007): 3528–33. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.3528.

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The atomic-scale structures and properties of thin films are critically determined by the various kinetic processes activated during their atomic assembly. Molecular dynamics simulations of growth allow these kinetic processes to be realistically addressed at a timescale that is difficult to reach using ab initio calculations. The newest approaches have begun to enable the growth simulation to be applied for a wide range of materials. Embedded atom method potentials can be successfully used to simulate the growth of closely packed metal multilayers. Modified charge transfer ionic + embedded atom method potentials are transferable between metallic and ionic materials and have been used to simulate the growth of metal oxides on metals. New analytical bond order potentials are now enabling significantly improved molecular dynamics simulations of semiconductor growth. Selected simulations are used to demonstrate the insights that can be gained about growth processes at surfaces.

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32

Lim, Byung-Wook, Young-Jun Lee, Joo-Hyung Kim, Hyeon-Taek Jeong, Tae-Won Ha, Eun-Mi Kim, Gi-Seok Heo, Young-Baek Kim, Hyeon-Ju Kim, and Ho-Saeng Lee. "Effect of Oxygen on the Structural/Electrical Properties of NIZO Films on Transparent Flexible Substrates." Journal of Nanoscience and Nanotechnology 15, no. 10 (October 1, 2015): 7522–25. http://dx.doi.org/10.1166/jnn.2015.11149.

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Thin film transparent oxides have attracted considerable attention over the last few decades for transparent electronic applications, such as flat panel displays, solar cells, touch-pads, and mobile devices. Metallic doped InZnO (IZO) films have been suggested for the transparent layer exhibiting semiconducting or metallic properties because of its controllable mobility and excellent electrical properties, but they show a degradation of the electrical performance under bending conditions. This study assessed Ni doped IZO (NIZO) films as a flexible transparent electrode on different flexible transparent substrates for flexible electronic applications. Thin NIZO films were deposited on cellulose, PES and glass substrates using a sputtering system with a single NIZO target (In2O3 73.8/ZnO 15.7/NiO 10.5 mol.%) at room temperature. During deposition of the NIZO films, the total flow rate of the carrier gas was maintained using a regulating system. The effects of the oxygen content in the carrier gas on the structural, electrical and optical properties of the thin films deposited on flexible substrates was characterized. The results highlight the feasibility of the transparent NIZO oxide layer on flexible substrates as a flexible electrode with a relatively high sheet resistance, which is strongly related to the crystallographic structure and oxygen content during the film deposition process.

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Zhang, Kai, Kai Du, Hao Liu, X. G. Zhang, Fanli Lan, Hanxuan Lin, Wengang Wei, et al. "Manipulating electronic phase separation in strongly correlated oxides with an ordered array of antidots." Proceedings of the National Academy of Sciences 112, no. 31 (July 20, 2015): 9558–62. http://dx.doi.org/10.1073/pnas.1512326112.

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The interesting transport and magnetic properties in manganites depend sensitively on the nucleation and growth of electronic phase-separated domains. By fabricating antidot arrays in La0.325Pr0.3Ca0.375MnO3 (LPCMO) epitaxial thin films, we create ordered arrays of micrometer-sized ferromagnetic metallic (FMM) rings in the LPCMO films that lead to dramatically increased metal–insulator transition temperatures and reduced resistances. The FMM rings emerge from the edges of the antidots where the lattice symmetry is broken. Based on our Monte Carlo simulation, these FMM rings assist the nucleation and growth of FMM phase domains increasing the metal–insulator transition with decreasing temperature or increasing magnetic field. This study points to a way in which electronic phase separation in manganites can be artificially controlled without changing chemical composition or applying external field.

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Rao, R. A., and C. B. Eom. "Epitaxial arrangements of thin films and heterostructures of copper oxide based isotropic metallic oxides for use as barriers in SNS junctions." Materials Science and Engineering: B 56, no. 2-3 (November 1998): 117–22. http://dx.doi.org/10.1016/s0921-5107(98)00242-6.

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Li, Huaping. "Electronically Pure Single Chirality Semiconducting Single-Walled Carbon Nanotube for Large Scale Electronic Devices." MRS Advances 2, no. 02 (2017): 83–88. http://dx.doi.org/10.1557/adv.2017.15.

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Abstract Carbon nanotube thin film transistors (TFTs) with characteristics resembling those of TFTs constructed on amorphous silicon, low-temperature polycrystalline silicon and metal oxides were fabricated on (6,5) single chirality single-walled carbon nanotube (SWCNT) thin film deposited from electronically pure semiconducting (6,5) single chirality single-walled carbon nanotube (SWCNT) ink. This ink was extracted in industrial scale from raw SWCNTs produced using high pressure carbon monoxide conversion, and deposited on pretreated substrates to form uniform and consistent (6,5) HiPCO SWCNT thin film using solution process. The (6,5) HiPCO SWCNT thin films were characterized as pure semiconductor without metallic impurities showing classic nonlinear current-bias curves in Schottky-type diodes. Both N-type and P-type (6,5) HiPCO SWCNT TFTs were fabricated with femto Ampere off-current and ION/IOFF ratio of 108 by depositing SiNx and HfO2 dielectrics on the top of (6,5) HiPCO SWCNT thin films, respectively. The (6,5) HiPCO SWCNT inverter with voltage gain of 52 was also demonstrated by wire-bonding one P-type HiPCO SWCNT TFT to one N-type HiPCO SWCNT TFT.

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Pappas, S. D., S. Grammatikopoulos, Panagiotis Poulopoulos, D. Trachylis, M. J. Velgakis, Efstathios I. Meletis, W. Schommers, and C. Politis. "Growth, Structure and Optical Properties of CuNi-Oxide Films for Nanophotonics and Photovoltaics." Journal of Nano Research 25 (October 2013): 61–66. http://dx.doi.org/10.4028/www.scientific.net/jnanor.25.61.

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Cu and Ni from CuNi metallic targets (composition 20-80 and 46-54 at.%) are deposited on Corning glass, quartz and the native oxide of Si (100) wafers by direct current magnetron sputtering in a high vacuum chamber (base pressure 5 x 10-5 mbar). The CuNi films, with thickness 40 200 nm, are post annealed at temperatures 400 - 500 °C in a furnace under atmospheric air in order to be fully oxidized. The structure of the films is studied by x-ray diffraction experiments. Phase separation of the oxides is evident. The optical properties are studied via ultraviolet-visible light absorption spectroscopy. The spectra of CuNi-oxide films are compared with the spectra of the pure CuO and NiO films. Features originating from both CuO and NiO are detected in the spectra of the CuNi-oxide thin films.

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37

Koshtyal, Yury, Ilya Mitrofanov, Denis Nazarov, Oleg Medvedev, Artem Kim, Ilya Ezhov, Aleksander Rumyantsev, Anatoly Popovich, and Maxim Yu Maximov. "Atomic Layer Deposition of Ni-Co-O Thin-Film Electrodes for Solid-State LIBs and the Influence of Chemical Composition on Overcapacity." Nanomaterials 11, no. 4 (April 2, 2021): 907. http://dx.doi.org/10.3390/nano11040907.

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Nanostructured metal oxides (MOs) demonstrate good electrochemical properties and are regarded as promising anode materials for high-performance lithium-ion batteries (LIBs). The capacity of nickel-cobalt oxides-based materials is among the highest for binary transition metals oxide (TMOs). In the present paper, we report the investigation of Ni-Co-O (NCO) thin films obtained by atomic layer deposition (ALD) using nickel and cobalt metallocenes in a combination with oxygen plasma. The formation of NCO films with different ratios of Ni and Co was provided by ALD cycles leading to the formation of nickel oxide (a) and cobalt oxide (b) in one supercycle (linear combination of a and b cycles). The film thickness was set by the number of supercycles. The synthesized films had a uniform chemical composition over the depth with an admixture of metallic nickel and carbon up to 4 at.%. All samples were characterized by a single NixCo1-xO phase with a cubic face-centered lattice and a uniform density. The surface of the NCO films was uniform, with rare inclusions of nanoparticles 15–30 nm in diameter. The growth rates of all films on steel were higher than those on silicon substrates, and this difference increased with increasing cobalt concentration in the films. In this paper, we propose a method for processing cyclic voltammetry curves for revealing the influence of individual components (nickel oxide, cobalt oxide and solid electrolyte interface—SEI) on the electrochemical capacity. The initial capacity of NCO films was augmented with an increase of nickel oxide content.

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38

Chang, Jeng-Kuei, Chiung-Hui Huang, Wen-Ta Tsai, I.-Wen Sun, and Po-Yu Chen. "Oxidation of Metallic Mn Thin Films Prepared in Butylmethylpyrrolidinium Bis(trifluoromethylsulfony)imide Ionic Liquid and the Pseudo-Capacitive Performance of the Anodized Oxides." ECS Transactions 6, no. 25 (December 19, 2019): 165–74. http://dx.doi.org/10.1149/1.2943235.

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39

Munasinghe Arachchige, Hashitha M. M., Dario Zappa, Nicola Poli, Nanda Gunawardhana, Nuwan H. Attanayake, and Elisabetta Comini. "Seed-Assisted Growth of TiO2 Nanowires by Thermal Oxidation for Chemical Gas Sensing." Nanomaterials 10, no. 5 (May 13, 2020): 935. http://dx.doi.org/10.3390/nano10050935.

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Herein, we report the catalyst assisted growth of TiO2 one-dimensional (1D) nanowires (NWs) on alumina substrates by the thermal oxidation technique. RF magnetron sputtering was used to deposit a thin Ti metallic layer on the alumina substrate, followed by an Au catalytic layer on the Ti metallic one. Thermal oxidation was carried out in an oxygen deficient environment. The optimal thermal growth temperature was 700 °C, in a mixture environment composed by Ar and O2. As a comparison, Ti films were also oxidized without the presence of the Au catalyst. However, without the Au catalyst, no growth of nanowires was observed. Furthermore, the effect of the oxidation temperature and the film thickness were also investigated. SEM, TEM, and EDX studies demonstrated the presence of Au nanoparticles on top of the NWs, indicating that the Au catalyst drove the growth process. Raman spectroscopy revealed the Rutile crystalline phase of TiO2 NWs. Gas testing measurements were carried out in the presence of a relative humidity of 40%, showing a reversible response to ethanol and H2 at various concentrations. Thanks to the moderate temperature and the easiness of the process, the presented synthesis technique is suitable to grow TiO2 NWs for many different applications.

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Jo, Euije, Dongwan Kim, and Jae-Young Leem. "Facile Synthesis of ZnO Thin Films at Low Temperatures Using an Additive-Free Electrochemical Oxidation Method." Korean Journal of Metals and Materials 58, no. 9 (September 5, 2020): 645–52. http://dx.doi.org/10.3365/kjmm.2020.58.9.645.

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Because of their simplicity and low equipment costs, various oxidation methods can be used to create metal oxides, but they still require long processing times and/or high temperatures. In this study, a new electrochemical oxidation (ECO) method, which oxidizes metal in DI water with a constant flowing current to both the cathode and anode, was developed to overcome the disadvantages of conventional oxidation methods. The mechanism of the ECO method is discussed. Metallic Zn films were oxidized by the ECO method in DI water for 1 h. The DI water temperature was varied from 30 to 90 <sup>o</sup>C to determine the optimal temperature for the ECO process. Increasing the temperature of the DI water led to distinct surface changes in the disk-shaped Zn plate. The intensity of diffraction peaks from the ZnO (002) plane gradually increased from 31.67 to 2806.48. The structural and optical properties of the ZnO thin film were enhanced as the temperature of the DI water approached 90 <sup>o</sup>C, which means that a high-quality ZnO thin film was synthesized using the ECO method at lower temperatures and shorter processing time compared with established oxidation methods. These results confirm the ECO method can be useful for the low-cost fabrication of transparent and flexible optoelectronic devices.

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Koo, B. R., J. W. Bae, and H. J. Ahn. "Improved Long-Term Stability of Transparent Conducting Electrodes Based on Double-Laminated Electrosprayed Antimony Tin Oxides and Ag Nanowires." Archives of Metallurgy and Materials 62, no. 2 (June 1, 2017): 1275–79. http://dx.doi.org/10.1515/amm-2017-0192.

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AbstractWe fabricated double-laminated antimony tin oxide/Ag nanowire electrodes by spin-coating and electrospraying. Compared to pure Ag nanowire electrodes and single-laminated antimony tin oxide/Ag nanowire electrodes, the double-laminated antimony tin oxide/Ag nanowire electrodes had superior transparent conducting electrode performances with sheet resistance ~19.8 Ω/□ and optical transmittance ~81.9%; this was due to uniform distribution of the connected Ag nanowires because of double lamination of the metallic Ag nanowires without Ag aggregation despite subsequent microwave heating at 250°C. They also exhibited excellent and superior long-term chemical and thermal stabilities and adhesion to substrate because double-laminated antimony tin oxide thin films act as the protective layers between Ag nanowires, blocking Ag atoms penetration.

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42

Nowak, Piotr, Wojciech Maziarz, Artur Rydosz, Kazimierz Kowalski, Magdalena Ziąbka, and Katarzyna Zakrzewska. "SnO2/TiO2 Thin Film n-n Heterostructures of Improved Sensitivity to NO2." Sensors 20, no. 23 (November 29, 2020): 6830. http://dx.doi.org/10.3390/s20236830.

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Thin-film n-n nanoheterostructures of SnO2/TiO2, highly sensitive to NO2, were obtained in a two-step process: (i) magnetron sputtering, MS followed by (ii) Langmuir-Blodgett, L–B, technique. Thick (200 nm) SnO2 base layers were deposited by MS and subsequently overcoated with a thin and discontinuous TiO2 film by means of L–B. Rutile nanopowder spread over the ethanol/chloroform/water formed a suspension, which was used as a source in L–B method. The morphology, crystallographic and electronic properties of the prepared sensors were studied by scanning electron microscopy, SEM, X-ray diffraction, XRD in glancing incidence geometry, GID, X-ray photoemission spectroscopy, XPS, and uv-vis-nir spectrophotometry, respectively. It was found that amorphous SnO2 films responded to relatively low concentrations of NO2 of about 200 ppb. A change of more than two orders of magnitude in the electrical resistivity upon exposure to NO2 was further enhanced in SnO2/TiO2 n-n nanoheterostructures. The best sensor responses RNO2/R0 were obtained at the lowest operating temperatures of about 120 °C, which is typical for nanomaterials. Response (recovery) times to 400 ppb NO2 were determined as a function of the operating temperature and indicated a significant decrease from 62 (42) s at 123 °C to 12 (19) s at 385 °C A much smaller sensitivity to H2 was observed, which might be advantageous for selective detection of nitrogen oxides. The influence of humidity on the NO2 response was demonstrated to be significantly below 150 °C and systematically decreased upon increase in the operating temperature up to 400 °C.

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Singh, Girjesh, S. B. Shrivastava, Deepti Jain, Swati Pandya, and V. Ganesan. "Effect of Molarity of Precursor Solution on Nanocrystalline Zinc Oxide Thin Films." Defect and Diffusion Forum 293 (August 2009): 99–105. http://dx.doi.org/10.4028/www.scientific.net/ddf.293.99.

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During the last two decades, the use of transparent conducting films of non-stoichiometric and doped metallic oxides for the conversion of solar energy into electrical energy has assumed great significance. A variety of materials, using various deposition techniques, has been tried for this purpose [1-3]. Among these various materials, zinc oxide (ZnO) is one of the prominent oxide semiconductors suitable for photovoltaic applications because of its high electrical conductivity and optical transmittance in the visible region of the solar spectrum [4]. Furthermore, thin films of ZnO have shown good chemical stability against hydrogen plasma, which is of prime importance in a-Si:H-based solar-cell fabrication. Thus, zinc oxide can serve as a good candidate for replacing SnO2 and indium tin oxide (ITO) films in Si:H-based solar cells. One of the outstanding features of ZnO is its large excitonic binding energy, i.e. 60meV, leading to the existence of excitons at room temperature and even at higher temperatures [5-8]. These unique characteristics have generated a wide range of applications of ZnO. For example, gas sensors [9], surface acoustic devices [10], transparent electrodes and solar cells. Many techniques are used for preparing the transparent conducting ZnO films, such as RF sputtering [11], evaporation [12], chemical vapour deposition [13], ion beam sputtering [14] and spray pyrolysis [15–18]. Among these, the spray pyrolysis technique has attracted considerable attention due to its simplicity and large-scale production combined with low-cost fabrication. By using this technique, one can produce large-area coatings without any need for ultra-high vacuum. Thus, the capital cost and the production cost of high-quality zinc oxide semiconductor thin films are lowest among all other techniques. In the present work, we have synthesized ZnO films by using the spray pyrolysis technique. A number of films have been prepared by changing the molarity of the precursor solution. The prepared films have been characterized with regard to their structural, morphological and electrical properties.

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Guillén, Cecilia, and José Herrero. "Structural Changes Induced by Heating in Sputtered NiO and Cr2O3 Thin Films as p-Type Transparent Conductive Electrodes." Electronic Materials 2, no. 2 (March 29, 2021): 49–59. http://dx.doi.org/10.3390/electronicmat2020005.

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NiO and Cr2O3 are transition metal oxides with a partially filled d electron band that supports p-type conduction. Both are transparent to the visible light due to optical absorption beginning at wavelengths below 0.4 μm and the creation of holes by metal vacancy defects. The defect and strain effects on the electronic characteristics of these materials need to be established. For this purpose, NiO and Cr2O3 thin films were deposited on unheated glass substrates by reactive DC sputtering from metallic targets. Their structural, morphological, optical and electrical properties were analyzed comparatively in the as-grown conditions (25 °C) and after heating in air at 300 °C or 500 °C. The cubic NiO structure was identified with some tensile strain in the as-grown conditions and compressive strain after heating. Otherwise, the chromium oxide layers were amorphous as grown at 25 °C and crystallized into hexagonal Cr2O3 at 300 °C or above also with compressive strain after heating. Both materials achieved the highest visible transmittance (72%) and analogous electrical conductivity (~10−4 S/cm) by annealing at 500 °C. The as-grown NiO films showed a higher conductivity (2.5 × 10−2 S/cm) but lower transmittance (34%), which were related to more defects causing tensile strain in these samples.

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Sharma, Yogesh, Pankaj Misra, Shojan P. Pavunny, and Ram S. Katiyar. "Unipolar resistive switching behavior of high-k ternary rare-earth oxide LaHoO3 thin films for non-volatile memory applications." MRS Proceedings 1729 (2015): 23–28. http://dx.doi.org/10.1557/opl.2015.92.

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ABSTRACTRare-earth oxides have attracted considerable research interest in resistive random access memories (ReRAMs) due to their compatibility with complementary metal-oxide semiconductor (CMOS) process. To this end we report unipolar resistive switching in a novel ternary rare-earth oxide LaHoO3 (LHO) to accelerate progress and to support advances in this emerging densely scalable research architecture. Amorphous thin films of LHO were fabricated on Pt/TiO2/SiO2/Si substrate by pulsed laser deposition, followed by sputter deposition of platinum top electrode through shadow mask in order to elucidate the resistive switching behavior of the resulting Pt/LHO/Pt metal-insulator-metal (MIM) device structure. Stable unipolar resistive switching characteristics with interesting switching parameters like, high resistance ratio of about 105 between high resistance state (HRS) and low resistance state (LRS), non-overlapping switching voltages with narrow dispersion, and excellent retention and endurance features were observed in Pt/LHO/Pt device structure. The observed resistive switching in LHO was explained by the formation/rupture of conductive filaments formed out of oxygen vacancies and metallic Ho atom. From the current-voltage characteristics of Pt/LHO/Pt structure, the conduction mechanism in LRS and HRS was found to be dominated by Ohm’s law and Poole-Frenkel emission, respectively.

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List, F. A., L. Heatherly, D. F. Lee, K. J. Leonard, and A. Goyal. "Oxidation of carbon on nickel-based metallic substrates: Implications for high-temperature superconductor coated conductors." Journal of Materials Research 20, no. 3 (March 1, 2005): 765–73. http://dx.doi.org/10.1557/jmr.2005.0103.

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Adhesion of thin films of epitaxial oxides to nickel-based metallic substrates is important for the successful development of high-temperature superconductor coated conductors. Detachment of epitaxial oxide buffer layers at the oxide/metal interface during either oxide growth or subsequent processing renders the conductor useless. In this study, thermal desorption spectroscopy (TDS) has been used to identify and understand one of the causes of buffer layer detachment, oxidation of carbon at the oxide–metal interface to form carbon monoxide. Results of TDS indicate that on the surface of a bare nickel-based alloy substrate, the rate of carbon oxidation depends on both the supply of carbon from the substrate and the supply of oxygen from the vapor. Sulfur at the surface of the alloy substrate reduces the rate of carbon oxidation. The effectiveness of various treatments of the bare substrate to eliminate CO formation and epitaxial oxide detachment has been demonstrated. TDS provides both a means to evaluate the kinetics of the oxidation reaction and a tool to assess the need and effectiveness of a substrate oxidation treatment.

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Shao, Jian, Hao Liu, Kai Zhang, Yang Yu, Weichao Yu, Hanxuan Lin, Jiebin Niu, et al. "Emerging single-phase state in small manganite nanodisks." Proceedings of the National Academy of Sciences 113, no. 33 (August 1, 2016): 9228–31. http://dx.doi.org/10.1073/pnas.1609656113.

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In complex oxides systems such as manganites, electronic phase separation (EPS), a consequence of strong electronic correlations, dictates the exotic electrical and magnetic properties of these materials. A fundamental yet unresolved issue is how EPS responds to spatial confinement; will EPS just scale with size of an object, or will the one of the phases be pinned? Understanding this behavior is critical for future oxides electronics and spintronics because scaling down of the system is unavoidable for these applications. In this work, we use La0.325Pr0.3Ca0.375MnO3 (LPCMO) single crystalline disks to study the effect of spatial confinement on EPS. The EPS state featuring coexistence of ferromagnetic metallic and charge order insulating phases appears to be the low-temperature ground state in bulk, thin films, and large disks, a previously unidentified ground state (i.e., a single ferromagnetic phase state emerges in smaller disks). The critical size is between 500 nm and 800 nm, which is similar to the characteristic length scale of EPS in the LPCMO system. The ability to create a pure ferromagnetic phase in manganite nanodisks is highly desirable for spintronic applications.

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Sahana, M. B., and S. A. Shivashankar. "Metalorganic chemical vapor deposition of highly oriented thin film composites of V2O5 and V6O13: Suppression of the metal–semiconductor transition in V6O13." Journal of Materials Research 19, no. 10 (October 1, 2004): 2859–70. http://dx.doi.org/10.1557/jmr.2004.0394.

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Thin films of vanadium oxides were grown on fused quartz by metalorganic chemical vapor deposition using vanadyl acetylacetonate as the precursor. Growth at temperatures ⩾560 °C results in composites of strongly (00l)-oriented V2O5 and V6O13. The dominant phase of the film changes from V2O5 to V6O13, and back to V2O5, as the growth temperature is raised from 560 to 570 °C, then to 580 °C, as evidenced by x-ray diffraction and Rutherford backscattering analyses. This reentrant-type growth trend was interpreted on the basis of the small difference in the free energy of formation of V2O5 and V6O13 and the presence of metal–oxygen bonds in the precursor. In contrast with single-crystalline V6O13, the film predominantly composed of highly oriented single-crystalline platelets of V6O13 did not undergo the semiconductor–metal transition at −123° K, despite the connectivity being well above the percolation threshold. Instead, a semiconductor-to-semiconductor transition was observed in this film, which is explained in terms of the observed relaxation of the edges of all the platelets of metallic V6O13 to semiconducting V2O5.

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Afonin, Nikolay N., and Vera A. Logacheva. "МОДЕЛИРОВАНИЕ ВЗАИМОДИФФУЗИИ И ФАЗООБРАЗОВАНИЯ В ТОНКОПЛЕНОЧНОЙ ДВУХСЛОЙНОЙ СИСТЕМЕ ПОЛИКРИСТАЛЛИЧЕСКИХ ОКСИДОВ ТИТАНА И КОБАЛЬТА." Kondensirovannye sredy i mezhfaznye granitsy = Condensed Matter and Interphases 21, no. 3 (September 26, 2019): 358–65. http://dx.doi.org/10.17308/kcmf.2019.21/1157.

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Предложена модель, развивающая теорию Даркена взаимной диффузии в бинарной системе с неограниченной растворимостью, на случай реакционной взаимодиффузии в двухслойной системе, состоящей из поликристаллических фаз оксидов двух металлов и содержащей подвижные и неподвижные компоненты в каждой из фаз. В рамках модели проведён численный анализ экспериментальных концентрационных распределений титана и кобальта в тонкоплёночной системе TiO2-x–Co1-yO, полученных методом резерфордовского обратного рассеяния, при отжиге в вакууме. Анализ выявил доминирующую роль диффузии подвижного кобальта в фазу TiO2-x по сравнению с диффузией подвижного титана в фазу Co1-yO и область локализации образования фаз сложных окси-дов в окрестности межфазной границы TiO2-x–Co1-yO. REFERENCES Chebotin V. N. Fizicheskaya khimiya tverdogo tela [Physical chemistry of a solid body]. M.: Khimiya Publ., 1982, 320 p. (in Russ.) Tretyakov Yu. D. Tverdofaznye reaktsii [Solid phase reactions]. M.: Khimiya Publ., 1978, 360 p. (in Russ.) Afonin N. N., Logacheva V. A. Interdiffusion and phase formation in the Fe–TiO2 thin-fi lm system. Semiconductors, 2017, v. 51(10), pp. 1300–1305. https://doi.org/10.1134/S1063782617100025 Afonin N. N., Logacheva V. A. Cobalt modifi cation of thin rutile fi lms magnetron-sputtered in vacuum technical. Technical Physics, 2018, v. 63(4), pp. 605–611. https://doi.org/10.1134/S1063784218040023 Kofstad P. Nonstoichiometry, diffusion, and electrical conductivity in binary metal oxides. Wiley-Interscience, 1972, 382 p. Smigelskas A. D., Kirkendall E. O. Zinc Diffusion in alpha brass. Trans. AIME, 1947, v. 171, pp. 130–142. Chambers S. A., Thevuthasan S., Farrow R. F. C., Marks R. F., Thiele J. U., Folks L., Samant M. G., Kellock A. J., Ruzycki N., Ederer D. L., Diebold U. Epita xial growth and properties of ferromagnetic co-doped TiO2 anatase. Appl. Phys. Lett., 2001, v. 79, pp. 3467–3469. https://doi.org/10.1063/1.1420434 Matsumoto Y., Murakami M., Shono T., Hasegawa T., Fukumura T., Kawasaki M., Ahmet P., Chikyow T., Koshihara S., Koinumaet H. Room-temperature ferromagnetism in transparent transition metal-doped titanium dioxide. Science, 2001, v. 291, pp. 854–856. https://doi.org/10.1126/science.1056186 Darken L. S. Diffusion, mobility and their interrelation through free energy in binary metallic systems. Trans. AMIE, 1948, v. 175, pp. 184–190. Samarsky A. A. [Theory of difference schemes]. M.: Nauka Publ., 1977, 656 с. (in Russ.) Afonin N. N., Logacheva V. A., Gerasimenko Yu. A., Dolgopolova E. A., Khoviv A. M. Interaction of cobalt and titanium with thin fi lms of their oxides during vacuum annealing // [Condensed Matter and Interphase], 2013, v. 15 (3), p. 232-237. URL: https://journals.vsu.ru/kcmf/article/view/902/984 (in Russ.)

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Stokstad, R. G., P. M. Jacobs, I. Tserruya, L. Sapir, and G. Mamane. "The dependence of heavy-ion-induced adhesion on energy loss and time." Journal of Materials Research 1, no. 2 (April 1986): 231–33. http://dx.doi.org/10.1557/jmr.1986.0231.

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The ability of heavy-ion beams to enhance the adhesion of thin metallic films to substrates has been studied as a function of projectile species. Measurements of the adhesion enhancement of a thin gold film to substrates of tantalum and silicon (with native oxides) have been made for beams of 12C, 16O, 28Si, 35Cl, and 58Ni at 2.85 MeV/nucleon. The threshold dose required to pass the Scotch tape peel test was found for the Au-Ta system to be D th (cm−2) = 1017 (dE / dx)−3±0.2 where dE/dx is the electronic stopping power (MeV mg−1 cm−2) of the ion in Au. For the Au-Si system, Dth = 6×1018 (dE/dx)−4.1±0.3. The steep dependence of D th on dE/dx found here is in contrast with an earlier measurement for the Au-Ta system by Tombrello et al. The adhesion enhancement was observed to decrease with time after the bombardment in a manner suggesting that diffusion of atoms through the gold film is important. The possible importance of small concentrations of extraneous atoms at the interface is discussed.

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Journal articles on the topic 'Rutile. Thin films. Metallic oxides'

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