Metal oxide nanorod arrays on monolithic substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Pu-Xian; Guo, Yanbing; Ren, Zheng

A metal oxide nanorod array structure according to embodiments disclosed herein includes a monolithic substrate having a surface and multiple channels, an interface layer bonded to the surface of the substrate, and a metal oxide nanorod array coupled to the substrate surface via the interface layer. The metal oxide can include ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide. The substrate can include a glass substrate, a plastic substrate, a silicon substrate, a ceramic monolith, and a stainless steel monolith. The ceramic can include cordierite, alumina, tin oxide, and titania. The nanorod array structure can includemore » a perovskite shell, such as a lanthanum-based transition metal oxide, or a metal oxide shell, such as ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide, or a coating of metal particles, such as platinum, gold, palladium, rhodium, and ruthenium, over each metal oxide nanorod. Structures can be bonded to the surface of a substrate and resist erosion if exposed to high velocity flow rates.« less

Interface trap and oxide charge generation under negative bias temperature instability of p-channel metal-oxide-semiconductor field-effect transistors with ultrathin plasma-nitrided SiON gate dielectrics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu Shiyang; Nakajima, Anri; Ohashi, Takuo

2005-12-01

The interface trap generation ({delta}N{sub it}) and fixed oxide charge buildup ({delta}N{sub ot}) under negative bias temperature instability (NBTI) of p-channel metal-oxide-semiconductor field-effect transistors (pMOSFETs) with ultrathin (2 nm) plasma-nitrided SiON gate dielectrics were studied using a modified direct-current-current-voltage method and a conventional subthreshold characteristic measurement. Different stress time dependences were shown for {delta}N{sub it} and {delta}N{sub ot}. At the earlier stress times, {delta}N{sub it} dominates the threshold voltage shift ({delta}V{sub th}) and {delta}N{sub ot} is negligible. With increasing stress time, the rate of increase of {delta}N{sub it} decreases continuously, showing a saturating trend for longer stress times, while {delta}N{submore » ot} still has a power-law dependence on stress time so that the relative contribution of {delta}N{sub ot} increases. The thermal activation energy of {delta}N{sub it} and the NBTI lifetime of pMOSFETs, compared at a given stress voltage, are independent of the peak nitrogen concentration of the SiON film. This indicates that plasma nitridation is a more reliable method for incorporating nitrogen in the gate oxide.« less

Pd/Cu-Oxide Nanoconjugate at Zeolite-Y Crystallite Crafting the Mesoporous Channels for Selective Oxidation of Benzyl-Alcohols.

PubMed

Sharma, Mukesh; Das, Biraj; Sharma, Mitu; Deka, Biplab K; Park, Young-Bin; Bhargava, Suresh K; Bania, Kusum K

2017-10-11

Solid-state grinding of palladium and copper salts allowed the growth of palladium/copper oxide interface at the zeolite-Y surface. The hybrid nanostructured material was used as reusable heterogeneous catalyst for selective oxidation of various benzyl alcohols. The large surface area provided by the zeolite-Y matrix highly influenced the catalytic activity, as well as the recyclability of the synthesized catalyst. Impregnation of PdO-CuO nanoparticles on zeolite crystallite leads to the generation of mesoporous channel that probably prevented the leaching of the metal-oxide nanoparticles and endorsed high mass transfer. Formation of mesoporous channel at the external surface of zeolite-Y was evident from transmission electron microscopy and surface area analysis. PdO-CuO nanoparticles were found to be within the range of 2-5 nm. The surface area of PdO-CuO-Y catalyst was found to be much lower than parent zeolite-Y. The decrease in surface area as well as the presence of hysteresis loop in the N 2 -adsoprtion isotherm further suggested successful encapsulation of PdO-CuO nanoparticles via the mesoporous channel formation. The high positive shifting in binding energy in both Pd and Cu was attributed to the influence of zeolite-Y framework on lattice contraction of metal oxides via confinement effect. PdO-CuO-Y catalyst was found to oxidize benzyl alcohol with 99% selectivity. On subjecting to microwave irradiation the same oxidation reaction was found to occur at ambient condition giving same conversion and selectivity.

Metal-oxide-semiconductor devices using Ga2O3 dielectrics on n-type GaN

NASA Astrophysics Data System (ADS)

Lee, Ching-Ting; Chen, Hong-Wei; Lee, Hsin-Ying

2003-06-01

Using a photoelectrochemical method involving a He-Cd laser, Ga2O3 oxide layers were directly grown on n-type GaN. We demonstrated the performance of the resultant metal-oxide-semiconductor devices based on the grown Ga2O3 layer. An extremely low reverse leakage current of 200 pA was achieved when devices operated at -20 V. Furthermore, high forward and reverse breakdown electric fields of 2.80 MV/cm and 5.70 MV/cm, respectively, were obtained. Using a photoassisted current-voltage method, a low interface state density of 2.53×1011 cm-2 eV-1 was estimated. The varactor devices permit formation of inversion layers, so that they may be applied for the fabrication of metal-oxide-semiconductor field-effect transistors.

Enhanced photoelectrochemical activity in all-oxide heterojunction devices based on correlated "metallic" oxides.

PubMed

Apgar, Brent A; Lee, Sungki; Schroeder, Lauren E; Martin, Lane W

2013-11-20

n-n Schottky, n-n ohmic, and p-n Schottky heterojunctions based on TiO2 /correlated "metallic" oxide couples exhibit strong solar-light absorption driven by the unique electronic structure of the "metallic" oxides. Photovoltaic and photocatalytic responses are driven by hot electron injection from the "metallic" oxide into the TiO2 , enabling new modalities of operation for energy systems. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Temperature dependence of single-event burnout in n-channel power MOSFET's

NASA Astrophysics Data System (ADS)

Johnson, G. H.; Schrimpf, R. D.; Galloway, K. F.; Koga, R.

1994-03-01

The temperature dependence of single-event burnout (SEB) in n-channel power metal-oxide-semiconductor field effect transistors (MOSFET's) is investigated experimentally and analytically. Experimental data are presented which indicate that the SEB susceptibility of the power MOSFET decreases with increasing temperature. A previously reported analytical model that describes the SEB mechanism is updated to include temperature variations. This model is shown to agree with the experimental trends.

Superior material qualities and transport properties of InGaN channel heterostructure grown by pulsed metal organic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Ya-Chao, Zhang; Xiao-Wei, Zhou; Sheng-Rui, Xu; Da-Zheng, Chen; Zhi-Zhe, Wang; Xing, Wang; Jin-Feng, Zhang; Jin-Cheng, Zhang; Yue, Hao

2016-01-01

Pulsed metal organic chemical vapor deposition is introduced into the growth of InGaN channel heterostructure for improving material qualities and transport properties. High-resolution transmission electron microscopy imaging shows the phase separation free InGaN channel with smooth and abrupt interface. A very high two-dimensional electron gas density of approximately 1.85 × 1013 cm-2 is obtained due to the superior carrier confinement. In addition, the Hall mobility reaches 967 cm2/V·s, owing to the suppression of interface roughness scattering. Furthermore, temperature-dependent Hall measurement results show that InGaN channel heterostructure possesses a steady two-dimensional electron gas density over the tested temperature range, and has superior transport properties at elevated temperatures compared with the traditional GaN channel heterostructure. The gratifying results imply that InGaN channel heterostructure grown by pulsed metal organic chemical vapor deposition is a promising candidate for microwave power devices. Project supported by the National Natural Science Foundation of China (Grant Nos. 61306017, 61334002, 61474086, and 11435010) and the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 61306017).

Back-channel-etch amorphous indium-gallium-zinc oxide thin-film transistors: The impact of source/drain metal etch and final passivation

NASA Astrophysics Data System (ADS)

Nag, Manoj; Bhoolokam, Ajay; Steudel, Soeren; Chasin, Adrian; Myny, Kris; Maas, Joris; Groeseneken, Guido; Heremans, Paul

2014-11-01

We report on the impact of source/drain (S/D) metal (molybdenum) etch and the final passivation (SiO2) layer on the bias-stress stability of back-channel-etch (BCE) configuration based amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs). It is observed that the BCE configurations TFTs suffer poor bias-stability in comparison to etch-stop-layer (ESL) TFTs. By analysis with transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS), as well as by a comparative analysis of contacts formed by other metals, we infer that this poor bias-stability for BCE transistors having Mo S/D contacts is associated with contamination of the back channel interface, which occurs by Mo-containing deposits on the back channel during the final plasma process of the physical vapor deposited SiO2 passivation.

Ultraviolet GaN photodetectors on Si via oxide buffer heterostructures with integrated short period oxide-based distributed Bragg reflectors and leakage suppressing metal-oxide-semiconductor contacts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Szyszka, A., E-mail: szyszka@ihp-microelectronics.com, E-mail: adam.szyszka@pwr.wroc.pl; Faculty of Microsystem Electronics and Photonics, Wroclaw University of Technology, Janiszewskiego 11/17, 50-372 Wroclaw; Lupina, L.

2014-08-28

Based on a novel double step oxide buffer heterostructure approach for GaN integration on Si, we present an optimized Metal-Semiconductor-Metal (MSM)-based Ultraviolet (UV) GaN photodetector system with integrated short-period (oxide/Si) Distributed Bragg Reflector (DBR) and leakage suppressing Metal-Oxide-Semiconductor (MOS) electrode contacts. In terms of structural properties, it is demonstrated by in-situ reflection high energy electron diffraction and transmission electron microscopy-energy dispersive x-ray studies that the DBR heterostructure layers grow with high thickness homogeneity and sharp interface structures sufficient for UV applications; only minor Si diffusion into the Y{sub 2}O{sub 3} films is detected under the applied thermal growth budget. Asmore » revealed by comparative high resolution x-ray diffraction studies on GaN/oxide buffer/Si systems with and without DBR systems, the final GaN layer structure quality is not significantly influenced by the growth of the integrated DBR heterostructure. In terms of optoelectronic properties, it is demonstrated that—with respect to the basic GaN/oxide/Si system without DBR—the insertion of (a) the DBR heterostructures and (b) dark current suppressing MOS contacts enhances the photoresponsivity below the GaN band-gap related UV cut-off energy by almost up to two orders of magnitude. Given the in-situ oxide passivation capability of grown GaN surfaces and the one order of magnitude lower number of superlattice layers in case of higher refractive index contrast (oxide/Si) systems with respect to classical III-N DBR superlattices, virtual GaN substrates on Si via functional oxide buffer systems are thus a promising robust approach for future GaN-based UV detector technologies.« less

Metal oxide, Group V-VI chalcogenides and GaN/AlGaN photodetectors

NASA Astrophysics Data System (ADS)

Hasan, Md. Rezaul

In this work, a simple, low-cost and catalyst free one-step solution processing of onedimensional Sb2S3 nanostructures on polyimide substrates was done. This structure demonstrated its potential application as a photoconductor in the UV and visible regime. Using-field emission scanning electron microscopy (SEM), grazing incidence X-Ray diffraction, Raman spectra and transmission electron microscopy measurements, it was shown that the Sb 2S3 films have high crystallinity, uniform morphology and nearstoichiometric composition. Further, using tauc plot, it was found that the films have a direct bandgap of 1.67 eV. MSM photodetectors, fabricated using these films showed a clear photo response in both UV as well as visible wavelength. These devices showed UV on/off ratio as high as 160 under the light intensity of 30 mW/cm2 and a small rise time and fall time of 44 ms 28 ms respectively. The effect of geometry of metal pad and bonding wire orientation of a multi-channel FET on the coupling of THz radiation was studied. The spatial variation images were taken by raster scan with the resolution of 0.07 mm steps in both x and y directions. An effective gate bias, where the effect of noise is minimum and photoresponse is maximum, was used for imaging. By applying VGS =-2.8V and VDS =380mV, the images were taken for all different combinations of activated bonding wires and metal pads. It was observed that, effect of bonding wire orientation is negligible for the large source pad as the radiation is coupled basically between drain and gate pad. Effect of drain bonding wire on coupling depends on the maximum width or diameter of metal pad and the incoming wavelength. In this work, Position of activated Drain pad and orientation of respective bonding wire defined the image tilting angle. Voltage drop across the shorting metal between drain pads, also played a role in increasing the asymmetry by selectively exciting a certain portion of FET Channels more than the other portion

Method of producing homogeneous mixed metal oxides and metal-metal oxide mixtures

DOEpatents

Quinby, Thomas C.

1978-01-01

Metal powders, metal oxide powders, and mixtures thereof of controlled particle size are provided by reacting an aqueous solution containing dissolved metal values with excess urea. Upon heating, urea reacts with water from the solution leaving a molten urea solution containing the metal values. The molten urea solution is heated to above about 180.degree. C. whereupon metal values precipitate homogeneously as a powder. The powder is reduced to metal or calcined to form oxide particles. One or more metal oxides in a mixture can be selectively reduced to produce metal particles or a mixture of metal and metal oxide particles.

Demonstration of an N7 integrated fab process for metal oxide EUV photoresist

NASA Astrophysics Data System (ADS)

De Simone, Danilo; Mao, Ming; Kocsis, Michael; De Schepper, Peter; Lazzarino, Frederic; Vandenberghe, Geert; Stowers, Jason; Meyers, Stephen; Clark, Benjamin L.; Grenville, Andrew; Luong, Vinh; Yamashita, Fumiko; Parnell, Doni

2016-03-01

Inpria has developed a directly patternable metal oxide hard-mask as a robust, high-resolution photoresist for EUV lithography. In this paper we demonstrate the full integration of a baseline Inpria resist into an imec N7 BEOL block mask process module. We examine in detail both the lithography and etch patterning results. By leveraging the high differential etch resistance of metal oxide photoresists, we explore opportunities for process simplification and cost reduction. We review the imaging results from the imec N7 block mask patterns and its process windows as well as routes to maximize the process latitude, underlayer integration, etch transfer, cross sections, etch equipment integration from cross metal contamination standpoint and selective resist strip process. Finally, initial results from a higher sensitivity Inpria resist are also reported. A dose to size of 19 mJ/cm2 was achieved to print pillars as small as 21nm.

Thin Film Complementary Metal Oxide Semiconductor (CMOS) Device Using a Single-Step Deposition of the Channel Layer

PubMed Central

Nayak, Pradipta K.; Caraveo-Frescas, J. A.; Wang, Zhenwei; Hedhili, M. N.; Wang, Q. X.; Alshareef, H. N.

2014-01-01

We report, for the first time, the use of a single step deposition of semiconductor channel layer to simultaneously achieve both n- and p-type transport in transparent oxide thin film transistors (TFTs). This effect is achieved by controlling the concentration of hydroxyl groups (OH-groups) in the underlying gate dielectrics. The semiconducting tin oxide layer was deposited at room temperature, and the maximum device fabrication temperature was 350°C. Both n and p-type TFTs showed fairly comparable performance. A functional CMOS inverter was fabricated using this novel scheme, indicating the potential use of our approach for various practical applications. PMID:24728223

Photochemical Hydrogen Doping Induced Embedded Two-Dimensional Metallic Channel Formation in InGaZnO at Room Temperature.

PubMed

Kim, Myeong-Ho; Lee, Young-Ahn; Kim, Jinseo; Park, Jucheol; Ahn, Seungbae; Jeon, Ki-Joon; Kim, Jeong Won; Choi, Duck-Kyun; Seo, Hyungtak

2015-10-27

The photochemical tunability of the charge-transport mechanism in metal-oxide semiconductors is of great interest since it may offer a facile but effective semiconductor-to-metal transition, which results from photochemically modified electronic structures for various oxide-based device applications. This might provide a feasible hydrogen (H)-radical doping to realize the effectively H-doped metal oxides, which has not been achieved by thermal and ion-implantation technique in a reliable and controllable way. In this study, we report a photochemical conversion of InGaZnO (IGZO) semiconductor to a transparent conductor via hydrogen doping to the local nanocrystallites formed at the IGZO/glass interface at room temperature. In contrast to thermal or ionic hydrogen doping, ultraviolet exposure of the IGZO surface promotes a photochemical reaction with H radical incorporation to surface metal-OH layer formation and bulk H-doping which acts as a tunable and stable highly doped n-type doping channel and turns IGZO to a transparent conductor. This results in the total conversion of carrier conduction property to the level of metallic conduction with sheet resistance of ∼16 Ω/□, room temperature Hall mobility of 11.8 cm(2) V(-1) sec(-1), the carrier concentration at ∼10(20) cm(-3) without any loss of optical transparency. We demonstrated successful applications of photochemically highly n-doped metal oxide via optical dose control to transparent conductor with excellent chemical and optical doping stability.

Preparation of uniform nanoparticles of ultra-high purity metal oxides, mixed metal oxides, metals, and metal alloys

DOEpatents

Woodfield, Brian F.; Liu, Shengfeng; Boerio-Goates, Juliana; Liu, Qingyuan; Smith, Stacey Janel

2012-07-03

In preferred embodiments, metal nanoparticles, mixed-metal (alloy) nanoparticles, metal oxide nanoparticles and mixed-metal oxide nanoparticles are provided. According to embodiments, the nanoparticles may possess narrow size distributions and high purities. In certain preferred embodiments, methods of preparing metal nanoparticles, mixed-metal nanoparticles, metal oxide nanoparticles and mixed-metal nanoparticles are provided. These methods may provide tight control of particle size, size distribution, and oxidation state. Other preferred embodiments relate to a precursor material that may be used to form nanoparticles. In addition, products prepared from such nanoparticles are disclosed.

95 MeV oxygen ion irradiation effects on N-channel MOSFETs

NASA Astrophysics Data System (ADS)

Prakash, A. P. G.; Ke, S. C.; Siddappa, K.

2003-09-01

The N-channel metal oxide semiconductor field effect transistors (MOSFETs) were exposed to 95 MeV oxygen ions, in the fluence range of 5 x 10(10) to 5 x 10(13) ions/cm(2). The influence of ion irradiation on threshold voltage (V-TH), linear drain current (I-DLin), leakage current (I-L), drain conductance (g(D)), transconductance (g(m)), mobility (mu) and drain saturation current (I-DSat) of MOSFETs was studied systematically for various fluence. The V-TH of the irradiated MOSFET was found to decrease significantly after irradiation. The interface (N-it) and oxide trapped charge (N-ot) were estimated from the subthreshold measurements and were found to increase after irradiation. The densities of oxide-trapped (DeltaN(it)) charge in irradiated MOSFETs were found to he higher than those of the interface trapped charge (DeltaN(ot)). The I-DLin and I-Dsat of MOSFETs were also found to decrease significantly after irradiation. Studies on effects of 95 MeV oxygen ion irradiation on g(m), g(D) and mu show a degradation varying front 70 to 75% after irradiation. The mobility degradation coefficients for N-it(alpha(it)) and N-ot(alpha(it)) were estimated. The results of these studies are presented and discussed.

Sub-0.5 V Highly Stable Aqueous Salt Gated Metal Oxide Electronics

PubMed Central

Park, Sungjun; Lee, SeYeong; Kim, Chang-Hyun; Lee, Ilseop; Lee, Won-June; Kim, Sohee; Lee, Byung-Geun; Jang, Jae-Hyung; Yoon, Myung-Han

2015-01-01

Recently, growing interest in implantable bionics and biochemical sensors spurred the research for developing non-conventional electronics with excellent device characteristics at low operation voltages and prolonged device stability under physiological conditions. Herein, we report high-performance aqueous electrolyte-gated thin-film transistors using a sol-gel amorphous metal oxide semiconductor and aqueous electrolyte dielectrics based on small ionic salts. The proper selection of channel material (i.e., indium-gallium-zinc-oxide) and precautious passivation of non-channel areas enabled the development of simple but highly stable metal oxide transistors manifested by low operation voltages within 0.5 V, high transconductance of ~1.0 mS, large current on-off ratios over 107, and fast inverter responses up to several hundred hertz without device degradation even in physiologically-relevant ionic solutions. In conjunction with excellent transistor characteristics, investigation of the electrochemical nature of the metal oxide-electrolyte interface may contribute to the development of a viable bio-electronic platform directly interfacing with biological entities in vivo. PMID:26271456

Photochemical metal organic deposition of metal oxides

NASA Astrophysics Data System (ADS)

Law, Wai Lung (Simon)

This thesis pertains to the study of the deposition of metal oxide thin films via the process of Photochemical Metal Organic Deposition (PMOD). In this process, an amorphous metal organic precursor thin film is subjected to irradiation under ambient conditions. Fragmentation of the metal precursor results from the photoreaction, leading to the formation of metal oxide thin films in the presence of oxygen. The advantage of PMOD lies in its ability to perform lithography of metal oxide thin film without the application of photoresist. The metal organic precursor can be imaged directly by photolysis through a lithography mask under ambient conditions. Thus the PMOD process provides an attractive alternative to the conventional VLSI fabrication process. Metal carboxylates and metal acetylacetonates complexes were used as the precursors for PMOD process in this thesis. Transition metal carboxylate and metal acetylacetonate complexes have shown previously that when deposited as amorphous thin films, they will undergo fragmentation upon photolysis, leading to the formation of metal oxide thin films under ambient conditions. In this thesis, the formation of main group metal oxides of aluminum, indium and tin, as well as the formation of rare-earth metal oxides of cerium and europium by PMOD from its corresponding metal organic precursor will be presented. The nature of the photoreactions as well as the properties of the thin films deposited by PMOD will be investigated. Doped metal oxide thin films can also be prepared using the PMOD process. By mixing the metal precursors prior to deposition in the desired ratio, precursor films containing more than one metal precursor can be obtained. Mixed metal oxide thin films corresponding to the original metal ratio, in the precursor mixture, can be obtained upon photolysis under ambient conditions. In this thesis, the properties of doped metal oxide thin films of europium doped aluminum oxide as well as tin doped indium oxide thin

An oxidized liquid metal-based microfluidic platform for tunable electronic device applications.

PubMed

Li, Guangyong; Parmar, Mitesh; Lee, Dong-Weon

2015-02-07

Easy movement of oxidized Galinstan in microfluidic channels is a promising way for the wide application of the non-toxic liquid metal. In this paper, two different surface modification techniques (physical and chemical) are reported, which dramatically improve the non-wetting characteristics of oxidized Galinstan in the microfluidic channel. In the physical technique, normal paper textures are transferred to the inner wall of polydimethylsiloxane (PDMS) channels and four types of nanoparticles are then coated on the surface of the wall for further improvement of the non-wetting characteristics. Highest advancing angle of 167° and receding angle of 151° are achieved on the paper-textured PDMS with titanium oxide (TiO2) nanoparticles. In the chemical technique, three types of inorganic acids are employed to generate dual-scale structures on the PDMS surface. The inner wall surface treated with sulfuric acid (H2SO4) shows the highest contact angle of 167° and a low hysteresis of ~14° in the dynamic measurement. Creating, transporting, separating and merging of oxidized Galinstan droplets are successfully demonstrated in the fabricated PDMS microfluidic channels. After optimization of these modification techniques, the potential application of tunable capacitors and electronic filters is realized by using liquid metal-based microfluidic devices.

Effects of growth temperature on the properties of InGaN channel heterostructures grown by pulsed metal organic chemical vapor deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yachao; Zhou, Xiaowei; Xu, Shengrui

Pulsed metal organic chemical vapor deposition (P-MOCVD) is introduced into the growth of high quality InGaN channel heterostructures. The effects of InGaN channel growth temperature on the structural and transport properties of the heterostructures are investigated in detail. High resolution x-ray diffraction (HRXRD) and Photoluminescence (PL) spectra indicate that the quality of InGaN channel strongly depends on the growth temperature. Meanwhile, the atomic force microscopy (AFM) results show that the interface morphology between the InGaN channel and the barrier layer also relies on the growth temperature. Since the variation of material properties of InGaN channel has a significant influence onmore » the electrical properties of InAlN/InGaN heterostructures, the optimal transport properties can be achieved by adjusting the growth temperature. A very high two dimension electron gas (2DEG) density of 1.92 × 10{sup 13} cm{sup −2} and Hall electron mobility of 1025 cm{sup 2}/(V⋅s) at room temperature are obtained at the optimal growth temperature around 740 °C. The excellent transport properties in our work indicate that the heterostructure with InGaN channel is a promising candidate for the microwave power devices, and the results in this paper will be instructive for further study of the InGaN channel heterostructures.« less

Low temperature processed complementary metal oxide semiconductor (CMOS) device by oxidation effect from capping layer.

PubMed

Wang, Zhenwei; Al-Jawhari, Hala A; Nayak, Pradipta K; Caraveo-Frescas, J A; Wei, Nini; Hedhili, M N; Alshareef, H N

2015-04-20

In this report, both p- and n-type tin oxide thin-film transistors (TFTs) were simultaneously achieved using single-step deposition of the tin oxide channel layer. The tuning of charge carrier polarity in the tin oxide channel is achieved by selectively depositing a copper oxide capping layer on top of tin oxide, which serves as an oxygen source, providing additional oxygen to form an n-type tin dioxide phase. The oxidation process can be realized by annealing at temperature as low as 190 °C in air, which is significantly lower than the temperature generally required to form tin dioxide. Based on this approach, CMOS inverters based entirely on tin oxide TFTs were fabricated. Our method provides a solution to lower the process temperature for tin dioxide phase, which facilitates the application of this transparent oxide semiconductor in emerging electronic devices field.

Extracting metals directly from metal oxides

DOEpatents

Wai, Chien M.; Smart, Neil G.; Phelps, Cindy

1997-01-01

A method of extracting metals directly from metal oxides by exposing the oxide to a supercritical fluid solvent containing a chelating agent is described. Preferably, the metal is an actinide or a lanthanide. More preferably, the metal is uranium, thorium or plutonium. The chelating agent forms chelates that are soluble in the supercritical fluid, thereby allowing direct removal of the metal from the metal oxide. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is selected from the group consisting of .beta.-diketones, halogenated .beta.-diketones, phosphinic acids, halogenated phosphinic acids, carboxylic acids, halogenated carboxylic acids, and mixtures thereof. In especially preferred embodiments, at least one of the chelating agents is fluorinated. The method provides an environmentally benign process for removing metals from metal oxides without using acids or biologically harmful solvents. The chelate and supercritical fluid can be regenerated, and the metal recovered, to provide an economic, efficient process.

Extracting metals directly from metal oxides

DOEpatents

Wai, C.M.; Smart, N.G.; Phelps, C.

1997-02-25

A method of extracting metals directly from metal oxides by exposing the oxide to a supercritical fluid solvent containing a chelating agent is described. Preferably, the metal is an actinide or a lanthanide. More preferably, the metal is uranium, thorium or plutonium. The chelating agent forms chelates that are soluble in the supercritical fluid, thereby allowing direct removal of the metal from the metal oxide. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is selected from the group consisting of {beta}-diketones, halogenated {beta}-diketones, phosphinic acids, halogenated phosphinic acids, carboxylic acids, halogenated carboxylic acids, and mixtures thereof. In especially preferred embodiments, at least one of the chelating agents is fluorinated. The method provides an environmentally benign process for removing metals from metal oxides without using acids or biologically harmful solvents. The chelate and supercritical fluid can be regenerated, and the metal recovered, to provide an economic, efficient process. 4 figs.

Low Temperature Processed Complementary Metal Oxide Semiconductor (CMOS) Device by Oxidation Effect from Capping Layer

PubMed Central

Wang, Zhenwei; Al-Jawhari, Hala A.; Nayak, Pradipta K.; Caraveo-Frescas, J. A.; Wei, Nini; Hedhili, M. N.; Alshareef, H. N.

2015-01-01

In this report, both p- and n-type tin oxide thin-film transistors (TFTs) were simultaneously achieved using single-step deposition of the tin oxide channel layer. The tuning of charge carrier polarity in the tin oxide channel is achieved by selectively depositing a copper oxide capping layer on top of tin oxide, which serves as an oxygen source, providing additional oxygen to form an n-type tin dioxide phase. The oxidation process can be realized by annealing at temperature as low as 190°C in air, which is significantly lower than the temperature generally required to form tin dioxide. Based on this approach, CMOS inverters based entirely on tin oxide TFTs were fabricated. Our method provides a solution to lower the process temperature for tin dioxide phase, which facilitates the application of this transparent oxide semiconductor in emerging electronic devices field. PMID:25892711

Ultralow power complementary inverter circuits using axially doped p- and n-channel Si nanowire field effect transistors.

PubMed

Van, Ngoc Huynh; Lee, Jae-Hyun; Whang, Dongmok; Kang, Dae Joon

2016-06-09

We have successfully synthesized axially doped p- and n-type regions on a single Si nanowire (NW). Diodes and complementary metal-oxide-semiconductor (CMOS) inverter devices using single axial p- and n-channel Si NW field-effect transistors (FETs) were fabricated. We show that the threshold voltages of both p- and n-channel Si NW FETs can be lowered to nearly zero by effectively controlling the doping concentration. Because of the high performance of the p- and n-type Si NW channel FETs, especially with regard to the low threshold voltage, the fabricated NW CMOS inverters have a low operating voltage (<3 V) while maintaining a high voltage gain (∼6) and ultralow static power dissipation (≤0.3 pW) at an input voltage of ±3 V. This result offers a viable way for the fabrication of a high-performance high-density logic circuit using a low-temperature fabrication process, which makes it suitable for flexible electronics.

Coaxial metal-oxide-semiconductor (MOS) Au/Ga2O3/GaN nanowires.

PubMed

Hsieh, Chin-Hua; Chang, Mu-Tung; Chien, Yu-Jen; Chou, Li-Jen; Chen, Lih-Juann; Chen, Chii-Dong

2008-10-01

Coaxial metal-oxide-semiconductor (MOS) Au-Ga2O3-GaN heterostructure nanowires were successfully fabricated by an in situ two-step process. The Au-Ga2O3 core-shell nanowires were first synthesized by the reaction of Ga powder, a mediated Au thin layer, and a SiO2 substrate at 800 degrees C. Subsequently, these core-shell nanowires were nitridized in ambient ammonia to form a GaN coating layer at 600 degrees C. The GaN shell is a single crystal, an atomic flat interface between the oxide and semiconductor that ensures that the high quality of the MOS device is achieved. These novel 1D nitride-based MOS nanowires may have promise as building blocks to the future nitride-based vertical nanodevices.

Metal oxide-polymer composites

NASA Technical Reports Server (NTRS)

Wellinghoff, Stephen T. (Inventor)

1997-01-01

A method of making metal oxide clusters in a single stage by reacting a metal oxide with a substoichiometric amount of an acid in the presence of an oxide particle growth terminator and solubilizer. A method of making a ceramer is also disclosed in which the metal oxide clusters are reacted with a functionalized polymer. The resultant metal oxide clusters and ceramers are also disclosed.

Metal oxide-polymer composites

NASA Technical Reports Server (NTRS)

Wellinghoff, Stephen T. (Inventor)

1994-01-01

A method of making metal oxide clusters in a single stage by reacting a metal oxide with a substoichiometric amount of an acid in the presence of an oxide particle growth terminator and solubilizer. A method of making a ceramer is also disclosed in which the metal oxide clusters are reacted with a functionalized polymer. The resultant metal oxide clusters and ceramers are also disclosed.

Time-resolved XAFS spectroscopic studies of B-H and N-H oxidative addition to transition metal catalysts relevant to hydrogen storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bitterwolf, Thomas E.

2014-12-09

Successful catalytic dehydrogenation of aminoborane, H 3NBH 3, prompted questions as to the potential role of N-H oxidative addition in the mechanisms of these processes. N-H oxidative addition reactions are rare, and in all cases appear to involve initial dative bonding to the metal by the amine lone pairs followed by transfer of a proton to the basic metal. Aminoborane and its trimethylborane derivative block this mechanism and, in principle, should permit authentic N-H oxidative attrition to occur. Extensive experimental work failed to confirm this hypothesis. In all cases either B-H complexation or oxidative addition of solvent C-H bonds dominatemore » the chemistry.« less

Comparison between the effects of positive noncatastrophic HMB ESD stress in n-channel and p-channel power MOSFET's

NASA Astrophysics Data System (ADS)

Zupac, Dragan; Kosier, Steven L.; Schrimpf, Ronald D.; Galloway, Kenneth F.; Baum, Keith W.

1991-10-01

The effect of noncatastrophic positive human body model (HBM) electrostatic discharge (ESD) stress on n-channel power MOSFETs is radically different from that on p-channel MOSFETs. In n-channel transistors, the stress causes negative shifts of the current-voltage characteristics indicative of positive charge trapping in the gate oxide. In p-channel transistors, the stress increases the drain-to-source leakage current, probably due to localized avalanche electron injection from the p-doped drain.

Metal-Free Functionalization of N,N-Dialkylanilines via Temporary Oxidation to N,N-Dialkylaniline N-Oxides and Group Transfer

PubMed Central

2015-01-01

A simple set of protocols for the controlled elaboration of anilines is reported allowing access to a diverse array of aminophenols, aminoarylsulfonates, alkylated anilines, and aminoanilines in 29–95% yield in a single laboratory operation from easily isolable, bench-stable N,N-dialkylaniline N-oxides. The introduction of new C–O, C–C, and C–N bonds on the aromatic ring is made possible by a temporary increase in oxidation level and excision of a weak N–O bond. PMID:24992642

Oxidative Modulation of Voltage-Gated Potassium Channels

PubMed Central

Sahoo, Nirakar; Hoshi, Toshinori

2014-01-01

Abstract Significance: Voltage-gated K+ channels are a large family of K+-selective ion channel protein complexes that open on membrane depolarization. These K+ channels are expressed in diverse tissues and their function is vital for numerous physiological processes, in particular of neurons and muscle cells. Potentially reversible oxidative regulation of voltage-gated K+ channels by reactive species such as reactive oxygen species (ROS) represents a contributing mechanism of normal cellular plasticity and may play important roles in diverse pathologies including neurodegenerative diseases. Recent Advances: Studies using various protocols of oxidative modification, site-directed mutagenesis, and structural and kinetic modeling provide a broader phenomenology and emerging mechanistic insights. Critical Issues: Physicochemical mechanisms of the functional consequences of oxidative modifications of voltage-gated K+ channels are only beginning to be revealed. In vivo documentation of oxidative modifications of specific amino-acid residues of various voltage-gated K+ channel proteins, including the target specificity issue, is largely absent. Future Directions: High-resolution chemical and proteomic analysis of ion channel proteins with respect to oxidative modification combined with ongoing studies on channel structure and function will provide a better understanding of how the function of voltage-gated K+ channels is tuned by ROS and the corresponding reducing enzymes to meet cellular needs. Antioxid. Redox Signal. 21, 933–952. PMID:24040918

Study Trapped Charge Distribution in P-Channel Silicon-Oxide-Nitride-Oxide-Silicon Memory Device Using Dynamic Programming Scheme

NASA Astrophysics Data System (ADS)

Li, Fu-Hai; Chiu, Yung-Yueh; Lee, Yen-Hui; Chang, Ru-Wei; Yang, Bo-Jun; Sun, Wein-Town; Lee, Eric; Kuo, Chao-Wei; Shirota, Riichiro

2013-04-01

In this study, we precisely investigate the charge distribution in SiN layer by dynamic programming of channel hot hole induced hot electron injection (CHHIHE) in p-channel silicon-oxide-nitride-oxide-silicon (SONOS) memory device. In the dynamic programming scheme, gate voltage is increased as a staircase with fixed step amplitude, which can prohibits the injection of holes in SiN layer. Three-dimensional device simulation is calibrated and is compared with the measured programming characteristics. It is found, for the first time, that the hot electron injection point quickly traverses from drain to source side synchronizing to the expansion of charged area in SiN layer. As a result, the injected charges quickly spread over on the almost whole channel area uniformly during a short programming period, which will afford large tolerance against lateral trapped charge diffusion by baking.

Studies on the InAlN/InGaN/InAlN/InGaN double channel heterostructures with low sheet resistance

NASA Astrophysics Data System (ADS)

Zhang, Yachao; Wang, Zhizhe; Xu, Shengrui; Chen, Dazheng; Bao, Weimin; Zhang, Jinfeng; Zhang, Jincheng; Hao, Yue

2017-11-01

High quality InAlN/InGaN/InAlN/InGaN double channel heterostructures were proposed and grown by metal organic chemical vapor deposition. Benefiting from the adoption of the pulsed growth method and Two-Step AlN interlayer, the material quality and interface characteristics of the double channel heterostructures are satisfactory. The results of the temperature-dependent Hall effect measurement indicated that the transport properties of the double channel heterostructures were superior to those of the traditional single channel heterostructures in the whole test temperature range. Meanwhile, the sheet resistance of the double channel heterostructures reached 218.5 Ω/□ at 300 K, which is the record of InGaN-based heterostructures. The good transport properties of the InGaN double channel heterostructures are beneficial to improve the performance of the microwave power devices based on nitride semiconductors.

Heat and mass transfer enhancement of nanofluids flow in the presence of metallic/metallic-oxides spherical nanoparticles

NASA Astrophysics Data System (ADS)

Qureshi, M. Zubair Akbar; Ali, Kashif; Iqbal, M. Farooq; Ashraf, Muhammad; Ahmad, Shazad

2017-01-01

The numerical study of heat and mass transfer for an incompressible magnetohydrodynamics (MHD) nanofluid flow containing spherical shaped nanoparticles through a channel with moving porous walls is presented. Further, another endeavour is to study the effect of two types of fluids, namely the metallic nanofluid (Au + water) and metallic-oxides nanofluid (TiO2 + water) are studied. The phenomena of spherical metallic and metallic-oxides nanoparticles have been also mathematically modelled by using the Hamilton-Crosser model. The influence of the governing parameters on the flow, heat and mass transfer aspects of the problem is discussed. The outcome of the investigation may be beneficial to the application of biotechnology and industrial purposes. Numerical solutions for the velocity, heat and mass transfer rate at the boundary are obtained and analysed.

Enhanced mobility in vertically scaled N-polar high-electron-mobility transistors using GaN/InGaN composite channels

NASA Astrophysics Data System (ADS)

Li, Haoran; Wienecke, Steven; Romanczyk, Brian; Ahmadi, Elaheh; Guidry, Matthew; Zheng, Xun; Keller, Stacia; Mishra, Umesh K.

2018-02-01

A GaN/InGaN composite channel design for vertically scaled N-polar high-electron-mobility transistor (HEMT) structures is proposed and demonstrated by metal-organic chemical vapor deposition. In a conventional N-polar HEMT structure, as the channel thickness (tch) decreases, the sheet charge density (ns) decreases, the electric field in the channel increases, and the centroid of the two-dimensional electron gas (2DEG) moves towards the back-barrier/channel interface, resulting in stronger scattering and lower electron mobility (μ). In this study, a thin InGaN layer was introduced in-between the channel and the AlGaN cap to increase the 2DEG density and reduce the electric field in the channel and therefore increase the electron mobility. The dependence of μ on the InGaN thickness (tInGaN) and the indium composition (xIn) was investigated for different channel thicknesses. With optimized tInGaN and xIn, significant improvements in electron mobility were observed. For a 6 nm channel HEMT structure, the electron mobility increased from 606 to 1141 cm2/(V.s) when the 6 nm thick pure GaN channel was replaced by the 4 nm GaN/2 nm In0.1Ga0.9N composite channel.

Fabrication of 4H-SiC n-channel IGBTs with ultra high blocking voltage

NASA Astrophysics Data System (ADS)

Yang, Xiaolei; Tao, Yonghong; Yang, Tongtong; Huang, Runhua; Song, Bai

2018-03-01

Owing to the conductivity modulation of silicon carbide (SiC) bipolar devices, n-channel insulated gate bipolar transistors (n-IGBTs) have a significant advantage over metal oxide semiconductor field effect transistors (MOSFETs) in ultra high voltage (UHV) applications. In this paper, backside grinding and laser annealing process were carried out to fabricate 4H-SiC n-IGBTs. The thickness of a drift layer was 120 μm, which was designed for a blocking voltage of 13 kV. The n-IGBTs carried a collector current density of 24 A/cm2 at a power dissipation of 300 W/cm2 when the gate voltage was 20 V, with a differential specific on-resistance of 140 mΩ·cm2.

Powerful Oxidizing Agents for the Oxidative Deintercalation of Lithium from Transition Metal Oxides

DTIC Science & Technology

1989-08-16

22217 11 TITLE dnrcluae Sec’.r/ 2 ’als.rit,catC Powerful Oxidizing Agents for the Oxidative Deintercalation of Lithium from Transition Metal Oxides...0 d dlentity by block number) FIELD GROUP SUB GROUP Oxidizing Agents, Lithium Oxides I - Deintercalation 19 AbS*RA?, trne on-tsxes~e it necessary...anid enit’y oy 010ck .1Uf~oer. N02+ andMoF6 are shown to be powerful oxidizing agents for the deintercalation of lithium from Li~oO2 an 62Ct . The

Spin-on metal oxide materials for N7 and beyond patterning applications

NASA Astrophysics Data System (ADS)

Mannaert, G.; Altamirano-Sanchez, E.; Hopf, T.; Sebaai, F.; Lorant, C.; Petermann, C.; Hong, S.-E.; Mullen, S.; Wolfer, E.; Mckenzie, D.; Yao, H.; Rahman, D.; Cho, J.-Y.; Padmanaban, M.; Piumi, D.

2017-04-01

There is a growing interest in new spin on metal oxide hard mask materials for advanced patterning solutions both in BEOL and FEOL processing. Understanding how these materials respond to plasma conditions may create a competitive advantage. In this study patterning development was done for two challenging FEOL applications where the traditional Si based films were replaced by EMD spin on metal oxides, which acted as highly selective hard masks. The biggest advantage of metal oxide hard masks for advanced patterning lays in the process window improvement at lower or similar cost compared to other existing solutions.

AlGaN channel field effect transistors with graded heterostructure ohmic contacts

NASA Astrophysics Data System (ADS)

Bajaj, Sanyam; Akyol, Fatih; Krishnamoorthy, Sriram; Zhang, Yuewei; Rajan, Siddharth

2016-09-01

We report on ultra-wide bandgap (UWBG) Al0.75Ga0.25N channel metal-insulator-semiconductor field-effect transistors (MISFETs) with heterostructure engineered low-resistance ohmic contacts. The low intrinsic electron affinity of AlN (0.6 eV) leads to large Schottky barriers at the metal-AlGaN interface, resulting in highly resistive ohmic contacts. In this work, we use a reverse compositional graded n++ AlGaN contact layer to achieve upward electron affinity grading, leading to a low specific contact resistance (ρsp) of 1.9 × 10-6 Ω cm2 to n-Al0.75Ga0.25N channels (bandgap ˜5.3 eV) with non-alloyed contacts. We also demonstrate UWBG Al0.75Ga0.25N channel MISFET device operation employing the compositional graded n++ ohmic contact layer and 20 nm atomic layer deposited Al2O3 as the gate-dielectric.

AlGaN/GaN metal-oxide-semiconductor high electron mobility transistors using Sc2O3 as the gate oxide and surface passivation

NASA Astrophysics Data System (ADS)

Mehandru, R.; Luo, B.; Kim, J.; Ren, F.; Gila, B. P.; Onstine, A. H.; Abernathy, C. R.; Pearton, S. J.; Gotthold, D.; Birkhahn, R.; Peres, B.; Fitch, R.; Gillespie, J.; Jenkins, T.; Sewell, J.; Via, D.; Crespo, A.

2003-04-01

We demonstrated that Sc2O3 thin films deposited by plasma-assisted molecular-beam epitaxy can be used simultaneously as a gate oxide and as a surface passivation layer on AlGaN/GaN high electron mobility transistors (HEMTs). The maximum drain source current, IDS, reaches a value of over 0.8 A/mm and is ˜40% higher on Sc2O3/AlGaN/GaN transistors relative to conventional HEMTs fabricated on the same wafer. The metal-oxide-semiconductor HEMTs (MOS-HEMTs) threshold voltage is in good agreement with the theoretical value, indicating that Sc2O3 retains a low surface state density on the AlGaN/GaN structures and effectively eliminates the collapse in drain current seen in unpassivated devices. The MOS-HEMTs can be modulated to +6 V of gate voltage. In particular, Sc2O3 is a very promising candidate as a gate dielectric and surface passivant because it is more stable on GaN than is MgO.

Metal oxide films on metal

DOEpatents

Wu, Xin D.; Tiwari, Prabhat

1995-01-01

A structure including a thin film of a conductive alkaline earth metal oxide selected from the group consisting of strontium ruthenium trioxide, calcium ruthenium trioxide, barium ruthenium trioxide, lanthanum-strontium cobalt oxide or mixed alkaline earth ruthenium trioxides thereof upon a thin film of a noble metal such as platinum is provided.

Methods for synthesizing metal oxide nanowires

DOEpatents

Sunkara, Mahendra Kumar; Kumar, Vivekanand; Kim, Jeong H.; Clark, Ezra Lee

2016-08-09

A method of synthesizing a metal oxide nanowire includes the steps of: combining an amount of a transition metal or a transition metal oxide with an amount of an alkali metal compound to produce a mixture; activating a plasma discharge reactor to create a plasma discharge; exposing the mixture to the plasma discharge for a first predetermined time period such that transition metal oxide nanowires are formed; contacting the transition metal oxide nanowires with an acid solution such that an alkali metal ion is exchanged for a hydrogen ion on each of the transition metal oxide nanowires; and exposing the transition metal oxide nanowires to the plasma discharge for a second predetermined time period to thermally anneal the transition metal oxide nanowires. Transition metal oxide nanowires produced using the synthesis methods described herein are also provided.

Characterization of Interface State in Silicon Carbide Metal Oxide Semiconductor Capacitors

NASA Astrophysics Data System (ADS)

Kao, Wei-Chieh

Silicon carbide (SiC) has always been considered as an excellent material for high temperature and high power devices. Since SiC is the only compound semiconductor whose native oxide is silicon dioxide (SiO2), it puts SiC in a unique position. Although SiC metal oxide semiconductor (MOS) technology has made significant progress in recent years, there are still a number of issues to be overcome before more commercial SiC devices can enter the market. The prevailing issues surrounding SiC MOSFET devices are the low channel mobility, the low quality of the oxide layer and the high interface state density at the SiC/SiO2 interface. Consequently, there is a need for research to be performed in order to have a better understanding of the factors causing the poor SiC/SiO2 interface properties. In this work, we investigated the generation lifetime in SiC materials by using the pulsed metal oxide semiconductor (MOS) capacitor method and measured the interface state density distribution at the SiC/SiO2 interface by using the conductance measurement and the high-low frequency capacitance technique. These measurement techniques have been performed on n-type and p-type SiC MOS capacitors. In the course of our investigation, we observed fast interface states at semiconductor-dielectric interfaces in SiC MOS capacitors that underwent three different interface passivation processes, such states were detected in the nitrided samples but not observed in PSG-passivated samples. This result indicate that the lack of fast states at PSG-passivated interface is one of the main reasons for higher channel mobility in PSG MOSFETs. In addition, the effect of mobile ions in the oxide on the response time of interface states has been investigated. In the last chapter we propose additional methods of investigation that can help elucidate the origin of the particular interface states, enabling a more complete understanding of the SiC/SiO2 material system.

Metal Oxide Thin Film Transistors on Paper Substrate: Fabrication, Characterization, and Printing Process

NASA Astrophysics Data System (ADS)

Choi, Nack-Bong

Flexible electronics is an emerging next-generation technology that offers many advantages such as light weight, durability, comfort, and flexibility. These unique features enable many new applications such as flexible display, flexible sensors, conformable electronics, and so forth. For decades, a variety of flexible substrates have been demonstrated for the application of flexible electronics. Most of them are plastic films and metal foils so far. For the fundamental device of flexible circuits, thin film transistors (TFTs) using poly silicon, amorphous silicon, metal oxide and organic semiconductor have been successfully demonstrated. Depending on application, low-cost and disposable flexible electronics will be required for convenience. Therefore it is important to study inexpensive substrates and to explore simple processes such as printing technology. In this thesis, paper is introduced as a new possible substrate for flexible electronics due to its low-cost and renewable property, and amorphous indium gallium zinc oxide (a-IGZO) TFTs are realized as the promising device on the paper substrate. The fabrication process and characterization of a-IGZO TFT on the paper substrate are discussed. a-IGZO TFTs using a polymer gate dielectric on the paper substrate demonstrate excellent performances with field effect mobility of ˜20 cm2 V-1 s-1, on/off current ratio of ˜106, and low leakage current, which show the enormous potential for flexible electronics application. In order to complement the n-channel a-IGZO TFTs and then enable complementary metal-oxide semiconductor (CMOS) circuit architectures, cuprous oxide is studied as a candidate material of p-channel oxide TFTs. In this thesis, a printing process is investigated as an alternative method for the fabrication of low-cost and disposable electronics. Among several printing methods, a modified offset roll printing that prints high resolution patterns is presented. A new method to fabricate a high resolution

Evaluation of metal/indium-tin-oxide for transparent low-resistance contacts to p-type GaN.

PubMed

Hou, Wenting; Stark, Christoph; You, Shi; Zhao, Liang; Detchprohm, Theeradetch; Wetzel, Christian

2012-08-10

In search of a better transparent contact to p-GaN, we analyze various metal/indium-tin-oxide (ITO) (Ag/ITO, AgCu/ITO, Ni/ITO, and NiZn/ITO) contact schemes and compare to Ni/Au, NiZn/Ag, and ITO. The metal layer boosts conductivity while the ITO thickness can be adjusted to constructive transmission interference on GaN that exceeds extraction from bare GaN. We find a best compromise for an Ag/ITO (3 nm/67 nm) ohmic contact with a relative transmittance of 97% of the bare GaN near 530 nm and a specific contact resistance of 0.03 Ω·cm2. The contact proves suitable for green light-emitting diodes in epi-up geometry.

PbSe Nanocrystal Solids for n- and p-Channel Thin Film Field-Effect Transistors

NASA Astrophysics Data System (ADS)

Talapin, Dmitri V.; Murray, Christopher B.

2005-10-01

Initially poorly conducting PbSe nanocrystal solids (quantum dot arrays or superlattices) can be chemically ``activated'' to fabricate n- and p-channel field effect transistors with electron and hole mobilities of 0.9 and 0.2 square centimeters per volt-second, respectively; with current modulations of about 103 to 104; and with current density approaching 3 × 104 amperes per square centimeter. Chemical treatments engineer the interparticle spacing, electronic coupling, and doping while passivating electronic traps. These nanocrystal field-effect transistors allow reversible switching between n- and p-transport, providing options for complementary metal oxide semiconductor circuits and enabling a range of low-cost, large-area electronic, optoelectronic, thermoelectric, and sensing applications.

Observations of the Kondo effect and its coexistence with ferromagnetism in a magnetically undoped metal oxide nanostructure

NASA Astrophysics Data System (ADS)

Sapkota, Keshab R.; Maloney, F. Scott; Wang, Wenyong

2018-04-01

In this work, we report unusual observations of Kondo effect and coexistence of Kondo effect and ferromagnetism in indium tin oxide (ITO) nanowires that were synthesized without incorporating any magnetic impurities. The temperature-dependent resistivity (ρ -T ) data exhibited an upturn below 80 K and then tended to saturate below 10 K. The ρ -T and magnetoresistance data were analyzed using the n -channel Kondo model, and from the obtained values of S =1 and n ˜1 , the nanowires were expected to be an underscreened Kondo system. A model was also proposed to explain the formation of localized S =1 spin centers in the ITO nanowires. This work could provide insights into the understanding of spin-related novel phenomena in metal oxide nanostructures.

Thin film hydrous metal oxide catalysts

DOEpatents

Dosch, Robert G.; Stephens, Howard P.

1995-01-01

Thin film (<100 nm) hydrous metal oxide catalysts are prepared by 1) synthesis of a hydrous metal oxide, 2) deposition of the hydrous metal oxide upon an inert support surface, 3) ion exchange with catalytically active metals, and 4) activating the hydrous metal oxide catalysts.

Positive and negative gain exceeding unity magnitude in silicon quantum well metal-oxide-semiconductor transistors

NASA Astrophysics Data System (ADS)

Hu, Gangyi; Wijesinghe, Udumbara; Naquin, Clint; Maggio, Ken; Edwards, H. L.; Lee, Mark

2017-10-01

Intrinsic gain (AV) measurements on Si quantum well (QW) n-channel metal-oxide-semiconductor (NMOS) transistors show that these devices can have |AV| > 1 in quantum transport negative transconductance (NTC) operation at room temperature. QW NMOS devices were fabricated using an industrial 45 nm technology node process incorporating ion implanted potential barriers to define a lateral QW in the conduction channel under the gate. While NTC at room temperature arising from transport through gate-controlled QW bound states has been previously established, it was unknown whether the quantum NTC mechanism could support gain magnitude exceeding unity. Bias conditions were found giving both positive and negative AV with |AV| > 1 at room temperature. This result means that QW NMOS devices could be useful in amplifier and oscillator applications.

Metal-interconnection-free integration of InGaN/GaN light emitting diodes with AlGaN/GaN high electron mobility transistors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Chao; Cai, Yuefei; Liu, Zhaojun

2015-05-04

We report a metal-interconnection-free integration scheme for InGaN/GaN light emitting diodes (LEDs) and AlGaN/GaN high electron mobility transistors (HEMTs) by combining selective epi removal (SER) and selective epitaxial growth (SEG) techniques. SER of HEMT epi was carried out first to expose the bottom unintentionally doped GaN buffer and the sidewall GaN channel. A LED structure was regrown in the SER region with the bottom n-type GaN layer (n-electrode of the LED) connected to the HEMTs laterally, enabling monolithic integration of the HEMTs and LEDs (HEMT-LED) without metal-interconnection. In addition to saving substrate real estate, minimal interface resistance between the regrownmore » n-type GaN and the HEMT channel is a significant improvement over metal-interconnection. Furthermore, excellent off-state leakage characteristics of the driving transistor can also be guaranteed in such an integration scheme.« less

Surface Preparation and Deposited Gate Oxides for Gallium Nitride Based Metal Oxide Semiconductor Devices

PubMed Central

Long, Rathnait D.; McIntyre, Paul C.

2012-01-01

The literature on polar Gallium Nitride (GaN) surfaces, surface treatments and gate dielectrics relevant to metal oxide semiconductor devices is reviewed. The significance of the GaN growth technique and growth parameters on the properties of GaN epilayers, the ability to modify GaN surface properties using in situ and ex situ processes and progress on the understanding and performance of GaN metal oxide semiconductor (MOS) devices are presented and discussed. Although a reasonably consistent picture is emerging from focused studies on issues covered in each of these topics, future research can achieve a better understanding of the critical oxide-semiconductor interface by probing the connections between these topics. The challenges in analyzing defect concentrations and energies in GaN MOS gate stacks are discussed. Promising gate dielectric deposition techniques such as atomic layer deposition, which is already accepted by the semiconductor industry for silicon CMOS device fabrication, coupled with more advanced physical and electrical characterization methods will likely accelerate the pace of learning required to develop future GaN-based MOS technology.

Electrically controlled wire-channel GaN/AlGaN transistor for terahertz plasma applications

NASA Astrophysics Data System (ADS)

Cywiński, G.; Yahniuk, I.; Kruszewski, P.; Grabowski, M.; Nowakowski-Szkudlarek, K.; Prystawko, P.; Sai, P.; Knap, W.; Simin, G. S.; Rumyantsev, S. L.

2018-03-01

We report on a design of fin-shaped channel GaN/AlGaN field-effect transistors developed for studying resonant terahertz plasma oscillations. Unlike common two dimensional FinFET transistor design, the gates were deposited only to the sides of the two dimensional electron gas channel, i.e., metal layers were not deposited on the top of the AlGaN. This side gate configuration allowed us to electrically control the conductivity of the channel by changing its width while keeping the carrier density and mobility virtually unchanged. Computer simulations and analytical model describe well the general shape of the characteristics. The side gate control of the channel width of these transistors allowed us to eliminate the so-called oblique plasma wave modes and paves the way towards future terahertz detectors and emitters using high quality factor plasma wave resonances.

Electroforming and Switching in Oxides of Transition Metals: The Role of Metal Insulator Transition in the Switching Mechanism

NASA Astrophysics Data System (ADS)

Chudnovskii, F. A.; Odynets, L. L.; Pergament, A. L.; Stefanovich, G. B.

1996-02-01

Electroforming and switching effects in sandwich structures based on anodic films of transition metal oxides (V, Nb, Ti, Fe, Ta, W, Zr, Hf, Mo) have been studied. After being electroformed, some materials exhibited current-controlled negative resistance with S-shapedV-Icharacteristics. For V, Fe, Ti, and Nb oxides, the temperature dependences of the threshold voltage have been measured. As the temperature increased,Vthdecreased to zero at a critical temperatureT0, which depended on the film material. Comparison of theT0values with the temperatures of metal-insulator phase transition for some compounds (Tt= 120 K for Fe3O4, 340 K for VO2, ∼500 K for Ti2O3, and 1070 K for NbO2) showed that switching was related to the transition in the applied electric field. Channels consisting of the above-mentioned lower oxides were formed in the initial anodic films during the electroforming. The possibility of formation of these oxides with a metal-insulator transition was confirmed by thermodynamic calculations.

Lithium metal reduction of plutonium oxide to produce plutonium metal

DOEpatents

Coops, Melvin S.

1992-01-01

A method is described for the chemical reduction of plutonium oxides to plutonium metal by the use of pure lithium metal. Lithium metal is used to reduce plutonium oxide to alpha plutonium metal (alpha-Pu). The lithium oxide by-product is reclaimed by sublimation and converted to the chloride salt, and after electrolysis, is removed as lithium metal. Zinc may be used as a solvent metal to improve thermodynamics of the reduction reaction at lower temperatures. Lithium metal reduction enables plutonium oxide reduction without the production of huge quantities of CaO--CaCl.sub.2 residues normally produced in conventional direct oxide reduction processes.

Graphene-supported metal oxide monolith

DOEpatents

Worsley, Marcus A.; Baumann, Theodore F.; Biener, Juergen; Biener, Monika A.; Wang, Yinmin; Ye, Jianchao; Tylski, Elijah

2017-01-10

A composition comprising at least one graphene-supported metal oxide monolith, said monolith comprising a three-dimensional structure of graphene sheets crosslinked by covalent carbon bonds, wherein the graphene sheets are coated by at least one metal oxide such as iron oxide or titanium oxide. Also provided is an electrode comprising the aforementioned graphene-supported metal oxide monolith, wherein the electrode can be substantially free of any carbon-black and substantially free of any binder.

Identifying the role of N-heteroatom location in the activity of metal catalysts for alcohol oxidation

DOE PAGES

Chan-Thaw, Carine E.; Veith, Gabriel M.; Villa, Alberto; ...

2015-04-02

Here, this work focuses on understanding how the bonding of nitrogen heteroatoms contained on/in a activated carbon support influence the stability and reactivity of a supported Pd catalyst for the oxidation of alcohols in solution. The results show that simply adding N groups via solution chemistry is insufficient to improve catalytic properties. Instead a strongly bound N moiety is required to activate the catalyst and stabilize the metal particles.

Metal oxide nanostructures with hierarchical morphology

DOEpatents

Ren, Zhifeng; Lao, Jing Yu; Banerjee, Debasish

2007-11-13

The present invention relates generally to metal oxide materials with varied symmetrical nanostructure morphologies. In particular, the present invention provides metal oxide materials comprising one or more metallic oxides with three-dimensionally ordered nanostructural morphologies, including hierarchical morphologies. The present invention also provides methods for producing such metal oxide materials.

Mesoporous metal oxide graphene nanocomposite materials

DOEpatents

Liu, Jun; Aksay, Ilhan A.; Kou, Rong; Wang, Donghai

2016-05-24

A nanocomposite material formed of graphene and a mesoporous metal oxide having a demonstrated specific capacity of more than 200 F/g with particular utility when employed in supercapacitor applications. A method for making these nanocomposite materials by first forming a mixture of graphene, a surfactant, and a metal oxide precursor, precipitating the metal oxide precursor with the surfactant from the mixture to form a mesoporous metal oxide. The mesoporous metal oxide is then deposited onto a surface of the graphene.

Operation of the GaSb p-channel metal-oxide-semiconductor field-effect transistors fabricated on (111)A surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nishi, K., E-mail: nishi@mosfet.t.u-tokyo.ac.jp; Takenaka, M.; Takagi, S.

2014-12-08

We demonstrate the operation of GaSb p-channel metal-oxide-semiconductor field-effect transistors (p-MOSFETs) on (111)A surfaces with Al{sub 2}O{sub 3} gate dielectrics formed by atomic-layer deposition at 150 °C. The p-MOSFETs on (111)A surfaces exhibit higher drain current and lower subthreshold swing than those on (100) surfaces. We find that the interface-state density (D{sub it}) values at the Al{sub 2}O{sub 3}/GaSb MOS interfaces on the (111)A surfaces are lower than those on the (100) surfaces, which can lead to performance enhancement of the GaSb p-MOSFETs on (111)A surfaces. The mobility of the GaSb p-MOSFETs on (111)A surfaces is 80% higher than that onmore » (100) surfaces.« less

Method for plating with metal oxides

DOEpatents

Silver, Gary L.; Martin, Frank S.

1994-08-23

A method of plating hydrous metal oxides on at least one substrate, which method is indifferent to the electrochemical properties of the substrate, and comprises reacting metallic ions in aqueous solution with an appropriate oxidizing agent such as sodium hypochlorite or calcium sulfite with oxygen under suitable conditions of pH and concentration such that oxidation and precipitation of metal oxide are sufficiently slow to allow satisfactory plating of metal oxide on the substrate.

Gas-generated thermal oxidation of a coordination cluster for an anion-doped mesoporous metal oxide.

PubMed

Hirai, Kenji; Isobe, Shigehito; Sada, Kazuki

2015-12-18

Central in material design of metal oxides is the increase of surface area and control of intrinsic electronic and optical properties, because of potential applications for energy storage, photocatalysis and photovoltaics. Here, we disclose a facile method, inspired by geochemical process, which gives rise to mesoporous anion-doped metal oxides. As a model system, we demonstrate that simple calcination of a multinuclear coordination cluster results in synchronic chemical reactions: thermal oxidation of Ti8O10(4-aminobenzoate)12 and generation of gases including amino-group fragments. The gas generation during the thermal oxidation of Ti8O10(4-aminobenzoate)12 creates mesoporosity in TiO2. Concurrently, nitrogen atoms contained in the gases are doped into TiO2, thus leading to the formation of mesoporous N-doped TiO2. The mesoporous N-doped TiO2 can be easily synthesized by calcination of the multinuclear coordination cluster, but shows better photocatalytic activity than the one prepared by a conventional sol-gel method. Owing to an intrinsic designability of coordination compounds, this facile synthetic will be applicable to a wide range of metal oxides and anion dopants.

Developmental phytotoxicity of metal oxide nanoparticles to Arabidopsis thaliana.

PubMed

Lee, Chang Woo; Mahendra, Shaily; Zodrow, Katherine; Li, Dong; Tsai, Yu-Chang; Braam, Janet; Alvarez, Pedro J J

2010-03-01

Phytotoxicity is an important consideration to understand the potential environmental impacts of manufactured nanomaterials. Here, we report on the effects of four metal oxide nanoparticles, aluminum oxide (nAl(2)O(3)), silicon dioxide (nSiO(2)), magnetite (nFe(3)O(4)), and zinc oxide (nZnO), on the development of Arabidopsis thaliana (Mouse-ear cress). Three toxicity indicators (seed germination, root elongation, and number of leaves) were quantified following exposure to each nanoparticle at three concentrations: 400, 2,000, and 4,000 mg/L. Among these particles, nZnO was most phytotoxic, followed by nFe(3)O(4), nSiO(2), and nAl(2)O(3), which was not toxic. Consequently, nZnO was further studied to discern the importance of particle size and zinc dissolution as toxicity determinants. Soluble zinc concentrations in nanoparticle suspensions were 33-fold lower than the minimum inhibitory concentration of dissolved zinc salt (ZnCl(2)), indicating that zinc dissolution could not solely account for the observed toxicity. Inhibition of seed germination by ZnO depended on particle size, with nanoparticles exerting higher toxicity than larger (micron-sized) particles at equivalent concentrations. Overall, this study shows that direct exposure to nanoparticles significantly contributed to phytotoxicity and underscores the need for eco-responsible disposal of wastes and sludge containing metal oxide nanoparticles.

Method for plating with metal oxides

DOEpatents

Silver, G.L.; Martin, F.S.

1994-08-23

A method is disclosed of plating hydrous metal oxides on at least one substrate, which method is indifferent to the electrochemical properties of the substrate, and comprises reacting metallic ions in aqueous solution with an appropriate oxidizing agent such as sodium hypochlorite or calcium sulfite with oxygen under suitable conditions of pH and concentration such that oxidation and precipitation of metal oxide are sufficiently slow to allow satisfactory plating of metal oxide on the substrate. 1 fig.

Oxide film on metal substrate reduced to form metal-oxide-metal layer structure

NASA Technical Reports Server (NTRS)

Youngdahl, C. A.

1967-01-01

Electrically conductive layer of zirconium on a zirconium-oxide film residing on a zirconium substrate is formed by reducing the oxide in a sodium-calcium solution. The reduced metal remains on the oxide surface as an adherent layer and seems to form a barrier that inhibits further reaction.

N-Channel field-effect transistors with floating gates for extracellular recordings.

PubMed

Meyburg, Sven; Goryll, Michael; Moers, Jürgen; Ingebrandt, Sven; Böcker-Meffert, Simone; Lüth, Hans; Offenhäusser, Andreas

2006-01-15

A field-effect transistor (FET) for recording extracellular signals from electrogenic cells is presented. The so-called floating gate architecture combines a complementary metal oxide semiconductor (CMOS)-type n-channel transistor with an independent sensing area. This concept allows the transistor and sensing area to be optimised separately. The devices are robust and can be reused several times. The noise level of the devices was smaller than of comparable non-metallised gate FETs. In addition to the usual drift of FET devices, we observed a long-term drift that has to be controlled for future long-term measurements. The device performance for extracellular signal recording was tested using embryonic rat cardiac myocytes cultured on fibronectin-coated chips. The extracellular cell signals were recorded before and after the addition of the cardioactive isoproterenol. The signal shapes of the measured action potentials were comparable to the non-metallised gate FETs previously used in similar experiments. The fabrication of the devices involved the process steps of standard CMOS that were necessary to create n-channel transistors. The implementation of a complete CMOS process would facilitate the integration of the logical circuits necessary for signal pre-processing on a chip, which is a prerequisite for a greater number of sensor spots in future layouts.

Hierarchical hybrid of Ni3N/N-doped reduced graphene oxide nanocomposite as a noble metal free catalyst for oxygen reduction reaction

NASA Astrophysics Data System (ADS)

Zhao, Qi; Li, Yingjun; Li, Yetong; Huang, Keke; Wang, Qin; Zhang, Jun

2017-04-01

Novel nickel nitride (Ni3N) nanoparticles supported on nitrogen-doped reduced graphene oxide nanosheets (N-RGOs) are synthesized via a facile strategy including hydrothermal and subsequent calcination methods, in which the reduced graphene oxide nanosheets (RGOs) are simultaneously doped with nitrogen species. By varying the content of the RGOs, a series of Ni3N/N-RGO nanocomposites are obtained. The Ni3N/N-RGO-30% hybrid nanocomposite exhibits superior catalytic activity towards oxygen reduction reaction (ORR) under alkaline condition (0.1 M KOH). Furthermore, this hybrid catalyst also demonstrates high tolerance to methanol poisoning. The RGO containing rich N confers the nanocomposite with large specific surface area and high electronic conduction ability, which can enhance the catalytic efficiency of Ni3N nanoparticles. The enhanced catalytic activity can be attributed to the synergistic effect between Ni3N and nitrogen doped reduced graphene oxide. In addition, the sufficient contact between Ni3N nanoparticles and the N-RGO nanosheets simultaneously promotes good nanoparticle dispersion and provides a consecutive activity sites to accelerate electron transport continuously, which further enhance the ORR performance. The Ni3N/N-RGO may be further an ideal candidate as efficient and inexpensive noble metal-free ORR electrocatalyst in fuel cells.

Metal atom oxidation laser

DOEpatents

Jensen, R.J.; Rice, W.W.; Beattie, W.H.

1975-10-28

A chemical laser which operates by formation of metal or carbon atoms and reaction of such atoms with a gaseous oxidizer in an optical resonant cavity is described. The lasing species are diatomic or polyatomic in nature and are readily produced by exchange or other abstraction reactions between the metal or carbon atoms and the oxidizer. The lasing molecules may be metal or carbon monohalides or monoxides.

Metal mobilisation in hydrothermal sediments at the TAG Hydrothermal Field (MAR, 26°N)

NASA Astrophysics Data System (ADS)

Dutrieux, A. M.; Lichtschlag, A.; Martins, S.; Barriga, F. J.; Petersen, S.; Murton, B. J.

2017-12-01

Metalliferous sediments in the vicinity of hydrothermal systems are enriched in base metals, but few studies have addressed their potential as mineral resources. These metalliferous sediments have been accumulated by different processes and reflect modifications of the primary mineral deposits by: oxidation of the chimney materials, in situ precipitation of low-temperature minerals and mass wasting. To understand the post-formation processes in metalliferous sediments, we investigated sub-seafloor metal mobilisation in different geological environments. This presentation focuses on the TAG Hydrothermal Field (Mid-Atlantic Ridge, 26°N) and explores sediment and pore water compositions using ICP-MS and ICP-OES. We use reactive transport modelling to interpret the degree of metal remobilisation and to identify the most important geochemical reactions in the different sediments. The pore water concentrations measured in sediments above inactive sulphide mounds present constant major elements composition that indicates this environment is dominated by complete exchange with seawater. The sediments, that are mainly composed of hematite and goethite formed during the oxidation of sulphides, have low Cu concentrations (< 0.1%) and the main part of their primary Cu and Zn content has likely been mobilized. Cu concentrations increase at the edges of the mounds (up to wt. 20%) or in distal depositionary channels (up to wt.10%) where sulphide minerals (e.g. pyrite, chalcopyrite and sphalerite) are still present in the sediments and capped by more recent sediment slumping. In the depositionary channels, pore waters show metal concentrations affected by diagenesis and redox-sensitive metals are released at depth (e.g. Mn2+ and Cu2+). The leaching of the primary sulphides (e.g. deprecated grains of chalcopyrite), and metal mobilisation lead to an enrichment of Cu and Zn at shallower depth. Here, some stratigraphic horizons scavenge metallic cations back into solid phases and

Mesoporous metal oxides and processes for preparation thereof

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suib, Steven L.; Poyraz, Altug Suleyman

A process for preparing a mesoporous metal oxide, i.e., transition metal oxide. Lanthanide metal oxide, a post-transition metal oxide and metalloid oxide. The process comprises providing an acidic mixture comprising a metal precursor, an interface modifier, a hydrotropic ion precursor, and a surfactant; and heating the acidic mixture at a temperature and for a period of time sufficient to form the mesoporous metal oxide. A mesoporous metal oxide prepared by the above process. A method of controlling nano-sized wall crystallinity and mesoporosity in mesoporous metal oxides. The method comprises providing an acidic mixture comprising a metal precursor, an interface modifier,more » a hydrotropic ion precursor, and a surfactant; and heating the acidic mixture at a temperature and for a period of time sufficient to control nano-sized wall crystallinity and mesoporosity in the mesoporous metal oxides. Mesoporous metal oxides and a method of tuning structural properties of mesoporous metal oxides.« less

Hydrogen-terminated diamond vertical-type metal oxide semiconductor field-effect transistors with a trench gate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Inaba, Masafumi, E-mail: inaba-ma@ruri.waseda.jp; Muta, Tsubasa; Kobayashi, Mikinori

2016-07-18

The hydrogen-terminated diamond surface (C-H diamond) has a two-dimensional hole gas (2DHG) layer independent of the crystal orientation. A 2DHG layer is ubiquitously formed on the C-H diamond surface covered by atomic-layer-deposited-Al{sub 2}O{sub 3}. Using Al{sub 2}O{sub 3} as a gate oxide, C-H diamond metal oxide semiconductor field-effect transistors (MOSFETs) operate in a trench gate structure where the diamond side-wall acts as a channel. MOSFETs with a side-wall channel exhibit equivalent performance to the lateral C-H diamond MOSFET without a side-wall channel. Here, a vertical-type MOSFET with a drain on the bottom is demonstrated in diamond with channel current modulationmore » by the gate and pinch off.« less

Metals and lipid oxidation. Contemporary issues.

PubMed

Schaich, K M

1992-03-01

Lipid oxidation is now recognized to be a critically important reaction in physiological and toxicological processes as well as in food products. This provides compelling reasons to understand what causes lipid oxidation in order to be able to prevent or control the reactions. Redox-active metals are major factors catalyzing lipid oxidation in biological systems. Classical mechanisms of direct electron transfer to double bonds by higher valence metals and of reduction of hydroperoxides by lower valence metals do not always account for patterns of metal catalysis of lipid oxidation in multiphasic or compartmentalized biological systems. To explain why oxidation kinetics, mechanisms, and products in molecular environments which are both chemically and physically complex often do not follow classical patterns predicted by model system studies, increased consideration must be given to five contemporary issues regarding metal catalysis of lipid oxidation: hypervalent non-heme iron or iron-oxygen complexes, heme catalysis mechanism(s), compartmentalization of reactions and lipid phase reactions of metals, effects of metals on product mixes, and factors affecting the mode of metal catalytic action.

Metal atom oxidation laser

DOEpatents

Jensen, R.J.; Rice, W.W.; Beattie, W.H.

1975-10-28

A chemical laser which operates by formation of metal or carbon atoms and reaction of such atoms with a gaseous oxidizer in an optical resonant cavity is described. The lasing species are diatomic or polyatomic in nature and are readily produced by exchange or other abstraction reactions between the metal or carbon atoms and the oxidizer. The lasing molecules may be metal or carbon monohalides or monoxides. (auth)

1D helix, 2D brick-wall and herringbone, and 3D interpenetration d10 metal-organic framework structures assembled from pyridine-2,6-dicarboxylic acid N-oxide.

PubMed

Wen, Li-Li; Dang, Dong-Bin; Duan, Chun-Ying; Li, Yi-Zhi; Tian, Zheng-Fang; Meng, Qing-Jin

2005-10-03

Five novel interesting d(10) metal coordination polymers, [Zn(PDCO)(H2O)2]n (PDCO = pyridine-2,6-dicarboxylic acid N-oxide) (1), [Zn2(PDCO)2(4,4'-bpy)2(H2O)2.3H2O]n (bpy = bipyridine) (2), [Zn(PDCO)(bix)]n (bix = 1,4-bis(imidazol-1-ylmethyl)benzene) (3), [Zn(PDCO)(bbi).0.5H2O]n (bbi = 1,1'-(1,4-butanediyl)bis(imidazole)) (4), and [Cd(PDCO)(bix)(1.5).1.5H2O]n (5), have been synthesized under hydrothermal conditions and structurally characterized. Polymer 1 possesses a one-dimensional (1D) helical chainlike structure with 4(1) helices running along the c-axis with a pitch of 10.090 Angstroms. Polymer 2 has an infinite chiral two-dimensional (2D) brick-wall-like layer structure in the ac plane built from achiral components, while both 3 and 4 exhibit an infinite 2D herringbone architecture, respectively extended in the ac and ab plane. Polymer 5 features a most remarkable and unique three-dimensional (3D) porous framework with 2-fold interpenetration related by symmetry, which contains channels in the b and c directions, both distributed in a rectangular grid fashion. Compounds 1-5, with systematic variation in dimensionality from 1D to 2D to 3D, are the first examples of d(10) metal coordination polymers into which pyridinedicarboxylic acid N-oxide has been introduced. In addition, polymers 1, 4, and 5 display strong blue fluorescent emissions in the solid state. Polymer 3 exhibits a strong SHG response, estimated to be approximately 0.9 times that of urea.

Surface protected lithium-metal-oxide electrodes

DOEpatents

Thackeray, Michael M.; Kang, Sun-Ho

2016-04-05

A lithium-metal-oxide positive electrode having a layered or spinel structure for a non-aqueous lithium electrochemical cell and battery is disclosed comprising electrode particles that are protected at the surface from undesirable effects, such as electrolyte oxidation, oxygen loss or dissolution by one or more lithium-metal-polyanionic compounds, such as a lithium-metal-phosphate or a lithium-metal-silicate material that can act as a solid electrolyte at or above the operating potential of the lithium-metal-oxide electrode. The surface protection significantly enhances the surface stability, rate capability and cycling stability of the lithium-metal-oxide electrodes, particularly when charged to high potentials.

Control of Ga-oxide interlayer growth and Ga diffusion in SiO2/GaN stacks for high-quality GaN-based metal-oxide-semiconductor devices with improved gate dielectric reliability

NASA Astrophysics Data System (ADS)

Yamada, Takahiro; Watanabe, Kenta; Nozaki, Mikito; Yamada, Hisashi; Takahashi, Tokio; Shimizu, Mitsuaki; Yoshigoe, Akitaka; Hosoi, Takuji; Shimura, Takayoshi; Watanabe, Heiji

2018-01-01

A simple and feasible method for fabricating high-quality and highly reliable GaN-based metal-oxide-semiconductor (MOS) devices was developed. The direct chemical vapor deposition of SiO2 films on GaN substrates forming Ga-oxide interlayers was carried out to fabricate SiO2/GaO x /GaN stacked structures. Although well-behaved hysteresis-free GaN-MOS capacitors with extremely low interface state densities below 1010 cm-2 eV-1 were obtained by postdeposition annealing, Ga diffusion into overlying SiO2 layers severely degraded the dielectric breakdown characteristics. However, this problem was found to be solved by rapid thermal processing, leading to the superior performance of the GaN-MOS devices in terms of interface quality, insulating property, and gate dielectric reliability.

Investigation of Short Channel Effects on Device Performance for 60nm NMOS Transistor

NASA Astrophysics Data System (ADS)

Chinnappan, U.; Sanudin, R.

2017-08-01

In the aggressively scaled complementary metal oxide semiconductor (CMOS) devices, shallower p-n junctions and low sheet resistances are essential for short-channel effect (SCE) control and high device performance. The SCE are attributed to two physical phenomena that are the limitation imposed on electron drift characteristics in channel and the modification of the threshold voltage (Vth) due to the shortening channel length. The decrement of Vth with decrement in gate length is a well-known attribute in SCE known as “threshold voltage roll-off’. In this research, the Technology Computer Aided Design (TCAD) was used to model the SCE phenomenon effect on 60nm n-type metal oxide semiconductor (NMOS) transistor. There are three parameters being investigated, which are the oxide thickness (Tox), gate length (L), acceptor concentration (Na). The simulation data were used to visualise the effect of SCE on the 60nm NMOS transistor. Simulation data suggest that all three parameters have significant effect on Vth, and hence on the transistor performance. It is concluded that there is a trade-off among these three parameters to obtain an optimized transistor performance.

Catalytic production of metal carbonyls from metal oxides

DOEpatents

Sapienza, Richard S.; Slegeir, William A.; Foran, Michael T.

1984-01-01

This invention relates to the formation of metal carbonyls from metal oxides and specially the formation of molybdenum carbonyl and iron carbonyl from their respective oxides. Copper is used here in admixed form or used in chemically combined form as copper molybdate. The copper/metal oxide combination or combined copper is utilized with a solvent, such as toluene and subjected to carbon monoxide pressure of 25 atmospheres or greater at about 150.degree.-260.degree. C. The reducing metal copper is employed in catalytic concentrations or combined concentrations as CuMoO.sub.4 and both hydrogen and water present serve as promoters. It has been found that the yields by this process have been salutary and that additionally the catalytic metal may be reused in the process to good effect.

Catalytic production of metal carbonyls from metal oxides

DOEpatents

Sapienza, R.S.; Slegeir, W.A.; Foran, M.T.

1984-01-06

This invention relates to the formation of metal carbonyls from metal oxides and specially the formation of molybdenum carbonyl and iron carbonyl from their respective oxides. Copper is used here in admixed form or used in chemically combined form as copper molybdate. The copper/metal oxide combination or combined copper is utilized with a solvent, such as toluene and subjected to carbon monoxide pressure of 25 atmospheres or greater at about 150 to 260/sup 0/C. The reducing metal copper is employed in catalytic concentrations or combined concentrations as CuMoO/sub 4/ and both hydrogen and water present serve as promoters. It has been found that the yields by this process have been salutary and that additionally the catalytic metal may be reused in the process to good effect. 3 tables.

Computational study on the half-metallicity in transition metal—oxide-incorporated 2D g-C3N4 nanosheets

NASA Astrophysics Data System (ADS)

Gao, Qian; Wang, Hui-Li; Zhang, Li-Fu; Hu, Shuang-Lin; Hu, Zhen-Peng

2018-06-01

In this study, based on the first-principles calculations, we systematically investigated the electronic and magnetic properties of the transition metal-oxide-incorporated 2D g-C3N4 nanosheet (labeled C3N4-TM-O, TM = Sc-Mn). The results suggest that the TM-O binds to g-C3N4 nanosheets strongly for all systems. We found that the 2D C3N4-TM-O framework is ferromagnetic for TM = Sc, Ti, V, Cr, while it is antiferromagnetic for TM = Mn. All the ferromagnetic systems exhibit the half-metallic property. Furthermore, Monte Carlo simulations based on the Heisenberg model suggest that the Curie temperatures ( T c ) of the C3N4-TM-O (TM = Sc, Ti, V, Cr) framework are 169 K, 68 K, 203 K, and 190 K, respectively. Based on Bader charge analysis, we found that the origin of the half-metallicity at Fermi energy can be partially attributed to the transfer of electrons from TM atoms to the g-C3N4 nanosheet. In addition, we found that not only electrons but also holes can induce half-metallicity for 2D g-C3N4 nanosheets, which may help to understand the origin of half-metallicity for graphitic carbon nitride.

Metal oxides for optoelectronic applications.

PubMed

Yu, Xinge; Marks, Tobin J; Facchetti, Antonio

2016-04-01

Metal oxides (MOs) are the most abundant materials in the Earth's crust and are ingredients in traditional ceramics. MO semiconductors are strikingly different from conventional inorganic semiconductors such as silicon and III-V compounds with respect to materials design concepts, electronic structure, charge transport mechanisms, defect states, thin-film processing and optoelectronic properties, thereby enabling both conventional and completely new functions. Recently, remarkable advances in MO semiconductors for electronics have been achieved, including the discovery and characterization of new transparent conducting oxides, realization of p-type along with traditional n-type MO semiconductors for transistors, p-n junctions and complementary circuits, formulations for printing MO electronics and, most importantly, commercialization of amorphous oxide semiconductors for flat panel displays. This Review surveys the uniqueness and universality of MOs versus other unconventional electronic materials in terms of materials chemistry and physics, electronic characteristics, thin-film fabrication strategies and selected applications in thin-film transistors, solar cells, diodes and memories.

Metal oxides for optoelectronic applications

NASA Astrophysics Data System (ADS)

Yu, Xinge; Marks, Tobin J.; Facchetti, Antonio

2016-04-01

Metal oxides (MOs) are the most abundant materials in the Earth's crust and are ingredients in traditional ceramics. MO semiconductors are strikingly different from conventional inorganic semiconductors such as silicon and III-V compounds with respect to materials design concepts, electronic structure, charge transport mechanisms, defect states, thin-film processing and optoelectronic properties, thereby enabling both conventional and completely new functions. Recently, remarkable advances in MO semiconductors for electronics have been achieved, including the discovery and characterization of new transparent conducting oxides, realization of p-type along with traditional n-type MO semiconductors for transistors, p-n junctions and complementary circuits, formulations for printing MO electronics and, most importantly, commercialization of amorphous oxide semiconductors for flat panel displays. This Review surveys the uniqueness and universality of MOs versus other unconventional electronic materials in terms of materials chemistry and physics, electronic characteristics, thin-film fabrication strategies and selected applications in thin-film transistors, solar cells, diodes and memories.

Mesoporous Transition Metal Oxides for Supercapacitors.

PubMed

Wang, Yan; Guo, Jin; Wang, Tingfeng; Shao, Junfeng; Wang, Dong; Yang, Ying-Wei

2015-10-14

Recently, transition metal oxides, such as ruthenium oxide (RuO₂), manganese dioxide (MnO₂), nickel oxides (NiO) and cobalt oxide (Co₃O₄), have been widely investigated as electrode materials for pseudo-capacitors. In particular, these metal oxides with mesoporous structures have become very hot nanomaterials in the field of supercapacitors owing to their large specific surface areas and suitable pore size distributions. The high specific capacities of these mesoporous metal oxides are resulted from the effective contacts between electrode materials and electrolytes as well as fast transportation of ions and electrons in the bulk of electrode and at the interface of electrode and electrolyte. During the past decade, many achievements on mesoporous transition metal oxides have been made. In this mini-review, we select several typical nanomaterials, such as RuO₂, MnO₂, NiO, Co₃O₄ and nickel cobaltite (NiCo₂O₄), and briefly summarize the recent research progress of these mesoporous transition metal oxides-based electrodes in the field of supercapacitors.

Investigation of 'surface donors' in Al2O3/AlGaN/GaN metal-oxide-semiconductor heterostructures: Correlation of electrical, structural, and chemical properties

NASA Astrophysics Data System (ADS)

Ťapajna, M.; Stoklas, R.; Gregušová, D.; Gucmann, F.; Hušeková, K.; Haščík, Š.; Fröhlich, K.; Tóth, L.; Pécz, B.; Brunner, F.; Kuzmík, J.

2017-12-01

III-N surface polarization compensating charge referred here to as 'surface donors' (SD) was analyzed in Al2O3/AlGaN/GaN metal-oxide-semiconductor (MOS) heterojunctions using scaled oxide films grown by metal-organic chemical vapor deposition at 600 °C. We systematically investigated impact of HCl pre-treatment prior to oxide deposition and post-deposition annealing (PDA) at 700 °C. SD density was reduced down to 1.9 × 1013 cm-2 by skipping HCl pre-treatment step as compared to 3.3 × 1013 cm-2 for structures with HCl pre-treatment followed by PDA. The nature and origin of SD was then analyzed based on the correlation between electrical, micro-structural, and chemical properties of the Al2O3/GaN interfaces with different SD density (NSD). From the comparison between distributions of interface traps of MOS heterojunction with different NSD, it is demonstrated that SD cannot be attributed to interface trapped charge. Instead, variation in the integrity of the GaOx interlayer confirmed by X-ray photoelectron spectroscopy is well correlated with NSD, indicating SD may be formed by border traps at the Al2O3/GaOx interface.

Effects of channel thickness on oxide thin film transistor with double-stacked channel layer

NASA Astrophysics Data System (ADS)

Lee, Kimoon; Kim, Yong-Hoon; Yoon, Sung-Min; Kim, Jiwan; Oh, Min Suk

2017-11-01

To improve the field effect mobility and control the threshold voltage ( V th ) of oxide thin film transistors (TFTs), we fabricated the oxide TFTs with double-stacked channel layers which consist of thick Zn-Sn-O (ZTO) and very thin In-Zn-O (IZO) layers. We investigated the effects of the thickness of thin conductive layer and the conductivity of thick layer on oxide TFTs with doublestacked channel layer. When we changed the thickness of thin conductive IZO channel layer, the resistivity values were changed. This resistivity of thin channel layer affected on the saturation field effect mobility and the off current of TFTs. In case of the thick ZTO channel layer which was deposited by sputtering in Ar: O2 = 10: 1, the device showed better performances than that which was deposited in Ar: O2 = 1: 1. Our TFTs showed high mobility ( μ FE ) of 40.7 cm2/Vs and V th of 4.3 V. We assumed that high mobility and the controlled V th were caused by thin conductive IZO layer and thick stable ZTO layer. Therefore, this double-stacked channel structure can be very promising way to improve the electrical characteristics of various oxide thin film transistors.

Method for producing metal oxide nanoparticles

DOEpatents

Phillips, Jonathan [Santa Fe, NM; Mendoza, Daniel [Santa Fe, NM; Chen, Chun-Ku [Albuquerque, NM

2008-04-15

Method for producing metal oxide nanoparticles. The method includes generating an aerosol of solid metallic microparticles, generating plasma with a plasma hot zone at a temperature sufficiently high to vaporize the microparticles into metal vapor, and directing the aerosol into the hot zone of the plasma. The microparticles vaporize in the hot zone into metal vapor. The metal vapor is directed away from the hot zone and into the cooler plasma afterglow where it oxidizes, cools and condenses to form solid metal oxide nanoparticles.

Oxidative Stress and Maxi Calcium-Activated Potassium (BK) Channels

PubMed Central

Hermann, Anton; Sitdikova, Guzel F.; Weiger, Thomas M.

2015-01-01

All cells contain ion channels in their outer (plasma) and inner (organelle) membranes. Ion channels, similar to other proteins, are targets of oxidative impact, which modulates ion fluxes across membranes. Subsequently, these ion currents affect electrical excitability, such as action potential discharge (in neurons, muscle, and receptor cells), alteration of the membrane resting potential, synaptic transmission, hormone secretion, muscle contraction or coordination of the cell cycle. In this chapter we summarize effects of oxidative stress and redox mechanisms on some ion channels, in particular on maxi calcium-activated potassium (BK) channels which play an outstanding role in a plethora of physiological and pathophysiological functions in almost all cells and tissues. We first elaborate on some general features of ion channel structure and function and then summarize effects of oxidative alterations of ion channels and their functional consequences. PMID:26287261

Entrapment of metal clusters in metal-organic framework channels by extended hooks anchored at open metal sites.

PubMed

Zheng, Shou-Tian; Zhao, Xiang; Lau, Samuel; Fuhr, Addis; Feng, Pingyun; Bu, Xianhui

2013-07-17

Reported here are the new concept of utilizing open metal sites (OMSs) for architectural pore design and its practical implementation. Specifically, it is shown here that OMSs can be used to run extended hooks (isonicotinates in this work) from the framework walls to the channel centers to effect the capture of single metal ions or clusters, with the concurrent partitioning of the large channel spaces into multiple domains, alteration of the host-guest charge relationship and associated guest-exchange properties, and transfer of OMSs from the walls to the channel centers. The concept of the extended hook, demonstrated here in the multicomponent dual-metal and dual-ligand system, should be generally applicable to a range of framework types.

Metal oxide nanostructures: preparation, characterization and functional applications as chemical sensors.

PubMed

Zappa, Dario; Bertuna, Angela; Comini, Elisabetta; Kaur, Navpreet; Poli, Nicola; Sberveglieri, Veronica; Sberveglieri, Giorgio

2017-01-01

Preparation and characterization of different metal oxide (NiO, WO 3 , ZnO, SnO 2 and Nb 2 O 5 ) nanostructures for chemical sensing are presented. p-Type (NiO) and n-type (WO 3 , SnO 2 , ZnO and Nb 2 O 5 ) metal oxide nanostructures were grown on alumina substrates using evaporation-condensation, thermal oxidation and hydrothermal techniques. Surface morphologies and crystal structures were investigated through scanning electron microscopy and Raman spectroscopy. Furthermore, different batches of sensors have been prepared, and their sensing performances towards carbon monoxide and nitrogen dioxide have been explored. Moreover, metal oxide nanowires have been integrated into an electronic nose and successfully applied to discriminate between drinking and contaminated water.

Dendritic core-shell nickel-iron-copper metal/metal oxide electrode for efficient electrocatalytic water oxidation.

PubMed

Zhang, Peili; Li, Lin; Nordlund, Dennis; Chen, Hong; Fan, Lizhou; Zhang, Biaobiao; Sheng, Xia; Daniel, Quentin; Sun, Licheng

2018-01-26

Electrochemical water splitting requires efficient water oxidation catalysts to accelerate the sluggish kinetics of water oxidation reaction. Here, we report a promisingly dendritic core-shell nickel-iron-copper metal/metal oxide electrode, prepared via dealloying with an electrodeposited nickel-iron-copper alloy as a precursor, as the catalyst for water oxidation. The as-prepared core-shell nickel-iron-copper electrode is characterized with porous oxide shells and metallic cores. This tri-metal-based core-shell nickel-iron-copper electrode exhibits a remarkable activity toward water oxidation in alkaline medium with an overpotential of only 180 mV at a current density of 10 mA cm -2 . The core-shell NiFeCu electrode exhibits pH-dependent oxygen evolution reaction activity on the reversible hydrogen electrode scale, suggesting that non-concerted proton-electron transfers participate in catalyzing the oxygen evolution reaction. To the best of our knowledge, the as-fabricated core-shell nickel-iron-copper is one of the most promising oxygen evolution catalysts.

Aerosol-spray diverse mesoporous metal oxides from metal nitrates.

PubMed

Kuai, Long; Wang, Junxin; Ming, Tian; Fang, Caihong; Sun, Zhenhua; Geng, Baoyou; Wang, Jianfang

2015-04-21

Transition metal oxides are widely used in solar cells, batteries, transistors, memories, transparent conductive electrodes, photocatalysts, gas sensors, supercapacitors, and smart windows. In many of these applications, large surface areas and pore volumes can enhance molecular adsorption, facilitate ion transfer, and increase interfacial areas; the formation of complex oxides (mixed, doped, multimetallic oxides and oxide-based hybrids) can alter electronic band structures, modify/enhance charge carrier concentrations/separation, and introduce desired functionalities. A general synthetic approach to diverse mesoporous metal oxides is therefore very attractive. Here we describe a powerful aerosol-spray method for synthesizing various mesoporous metal oxides from low-cost nitrate salts. During spray, thermal heating of precursor droplets drives solvent evaporation and induces surfactant-directed formation of mesostructures, nitrate decomposition and oxide cross-linking. Thirteen types of monometallic oxides and four groups of complex ones are successfully produced, with mesoporous iron oxide microspheres demonstrated for photocatalytic oxygen evolution and gas sensing with superior performances.

Aerosol-spray diverse mesoporous metal oxides from metal nitrates

PubMed Central

Kuai, Long; Wang, Junxin; Ming, Tian; Fang, Caihong; Sun, Zhenhua; Geng, Baoyou; Wang, Jianfang

2015-01-01

Transition metal oxides are widely used in solar cells, batteries, transistors, memories, transparent conductive electrodes, photocatalysts, gas sensors, supercapacitors, and smart windows. In many of these applications, large surface areas and pore volumes can enhance molecular adsorption, facilitate ion transfer, and increase interfacial areas; the formation of complex oxides (mixed, doped, multimetallic oxides and oxide-based hybrids) can alter electronic band structures, modify/enhance charge carrier concentrations/separation, and introduce desired functionalities. A general synthetic approach to diverse mesoporous metal oxides is therefore very attractive. Here we describe a powerful aerosol-spray method for synthesizing various mesoporous metal oxides from low-cost nitrate salts. During spray, thermal heating of precursor droplets drives solvent evaporation and induces surfactant-directed formation of mesostructures, nitrate decomposition and oxide cross-linking. Thirteen types of monometallic oxides and four groups of complex ones are successfully produced, with mesoporous iron oxide microspheres demonstrated for photocatalytic oxygen evolution and gas sensing with superior performances. PMID:25897988

Mesoporous Transition Metal Oxides for Supercapacitors

PubMed Central

Wang, Yan; Guo, Jin; Wang, Tingfeng; Shao, Junfeng; Wang, Dong; Yang, Ying-Wei

2015-01-01

Recently, transition metal oxides, such as ruthenium oxide (RuO2), manganese dioxide (MnO2), nickel oxides (NiO) and cobalt oxide (Co3O4), have been widely investigated as electrode materials for pseudo-capacitors. In particular, these metal oxides with mesoporous structures have become very hot nanomaterials in the field of supercapacitors owing to their large specific surface areas and suitable pore size distributions. The high specific capacities of these mesoporous metal oxides are resulted from the effective contacts between electrode materials and electrolytes as well as fast transportation of ions and electrons in the bulk of electrode and at the interface of electrode and electrolyte. During the past decade, many achievements on mesoporous transition metal oxides have been made. In this mini-review, we select several typical nanomaterials, such as RuO2, MnO2, NiO, Co3O4 and nickel cobaltite (NiCo2O4), and briefly summarize the recent research progress of these mesoporous transition metal oxides-based electrodes in the field of supercapacitors. PMID:28347088

Metal Organic Framework-Templated Chemiresistor: Sensing Type Transition from P-to-N Using Hollow Metal Oxide Polyhedron via Galvanic Replacement.

PubMed

Jang, Ji-Soo; Koo, Won-Tae; Choi, Seon-Jin; Kim, Il-Doo

2017-08-30

Facile synthesis of porous nanobuilding blocks with high surface area and uniform catalyst functionalization has always been regarded as an essential requirement for the development of highly sensitive and selective chemical sensors. Metal-organic frameworks (MOFs) are considered as one of the most ideal templates due to their ability to encapsulate ultrasmall catalytic nanoparticles (NPs) in microporous MOF structures in addition to easy removal of the sacrificial MOF scaffold by calcination. Here, we introduce a MOFs derived n-type SnO 2 (n-SnO 2 ) sensing layer with hollow polyhedron structures, obtained from p-n transition of MOF-templated p-type Co 3 O 4 (p-Co 3 O 4 ) hollow cubes during galvanic replacement reaction (GRR). In addition, the Pd NPs encapsulated in MOF and residual Co 3 O 4 clusters partially remained after GRR led to uniform functionalization of efficient cocatalysts (PdO NPs and p-Co 3 O 4 islands) on the porous and hollow polyhedron SnO 2 structures. Due to high gas accessibility through the meso- and macrosized pores in MOF-templated oxides and effective modulation of electron depletion layer assisted by the creation of numerous p-n junctions, the GRR-treated SnO 2 structures exhibited 21.9-fold higher acetone response (R air /R gas = 22.8 @ 5 ppm acetone, 90%RH) compared to MOF-templated p-Co 3 O 4 hollow structures. To the best of our knowledge, the selectivity and response amplitudes reported here for the detection of acetone are superior to those MOF derived metal oxide sensing layers reported so far. Our results demonstrate that highly active MOF-derived sensing layers can be achieved via p-n semiconducting phase transition, driven by a simple and versatile GRR process combined with MOF templating route.

Reactive metal-oxide interfaces: A microscopic view

NASA Astrophysics Data System (ADS)

Picone, A.; Riva, M.; Brambilla, A.; Calloni, A.; Bussetti, G.; Finazzi, M.; Ciccacci, F.; Duò, L.

2016-03-01

Metal-oxide interfaces play a fundamental role in determining the functional properties of artificial layered heterostructures, which are at the root of present and future technological applications. Magnetic exchange and magnetoelectric coupling, spin filtering, metal passivation, catalytic activity of oxide-supported nano-particles are just few examples of physical and chemical processes arising at metal-oxide hybrid systems, readily exploited in working devices. These phenomena are strictly correlated with the chemical and structural characteristics of the metal-oxide interfacial region, making a thorough understanding of the atomistic mechanisms responsible of its formation a prerequisite in order to tailor the device properties. The steep compositional gradient established upon formation of metal-oxide heterostructures drives strong chemical interactions at the interface, making the metal-oxide boundary region a complex system to treat, both from an experimental and a theoretical point of view. However, once properly mastered, interfacial chemical interactions offer a further degree of freedom for tuning the material properties. The goal of the present review is to provide a summary of the latest achievements in the understanding of metal/oxide and oxide/metal layered systems characterized by reactive interfaces. The influence of the interface composition on the structural, electronic and magnetic properties will be highlighted. Particular emphasis will be devoted to the discussion of ultra-thin epitaxial oxides stabilized on highly oxidizable metals, which have been rarely exploited as oxide supports as compared to the much more widespread noble and quasi noble metallic substrates. In this frame, an extensive discussion is devoted to the microscopic characterization of interfaces between epitaxial metal oxides and the Fe(001) substrate, regarded from the one hand as a prototypical ferromagnetic material and from the other hand as a highly oxidizable metal.

Experimental study of three-dimensional fin-channel charge trapping flash memories with titanium nitride and polycrystalline silicon gates

NASA Astrophysics Data System (ADS)

Liu, Yongxun; Matsukawa, Takashi; Endo, Kazuhiko; O'uchi, Shinichi; Tsukada, Junichi; Yamauchi, Hiromi; Ishikawa, Yuki; Mizubayashi, Wataru; Morita, Yukinori; Migita, Shinji; Ota, Hiroyuki; Masahara, Meishoku

2014-01-01

Three-dimensional (3D) fin-channel charge trapping (CT) flash memories with different gate materials of physical-vapor-deposited (PVD) titanium nitride (TiN) and n+-polycrystalline silicon (poly-Si) have successfully been fabricated by using (100)-oriented silicon-on-insulator (SOI) wafers and orientation-dependent wet etching. Electrical characteristics of the fabricated flash memories including statistical threshold voltage (Vt) variability, endurance, and data retention have been comparatively investigated. It was experimentally found that a larger memory window and a deeper erase are obtained in PVD-TiN-gated metal-oxide-nitride-oxide-silicon (MONOS)-type flash memories than in poly-Si-gated poly-Si-oxide-nitride-oxide-silicon (SONOS)-type memories. The larger memory window and deeper erase of MONOS-type flash memories are contributed by the higher work function of the PVD-TiN metal gate than of the n+-poly-Si gate, which is effective for suppressing electron back tunneling during erase operation. It was also found that the initial Vt roll-off due to the short-channel effect (SCE) is directly related to the memory window roll-off when the gate length (Lg) is scaled down to 46 nm or less.

Molecular Level Coating of Metal Oxide Particles

NASA Technical Reports Server (NTRS)

McDaniel, Patricia R. (Inventor); St.Clair, Terry L. (Inventor)

2002-01-01

Polymer encapsulated metal oxide particles are prepared by combining a polyamide acid in a polar osmotic solvent with a metal alkoxide solution. The polymer was imidized and the metal oxide formed simultaneously in a refluxing organic solvent. The resulting polymer-metal oxide is an intimately mixed commingled blend, possessing, synergistic properties of both the polymer and preceramic metal oxide. The encapsulated metal oxide particles have multiple uses including, being useful in the production of skin lubricating creams, weather resistant paints, as a filler for paper. making ultraviolet light stable filled printing ink, being extruded into fibers or ribbons, and coatings for fibers used in the production of composite structural panels.

Molecular Level Coating for Metal Oxide Particles

NASA Technical Reports Server (NTRS)

McDaniel, Patricia R. (Inventor); Saint Clair, Terry L. (Inventor)

2000-01-01

Polymer encapsulated metal oxide particles are prepared by combining a polyamide acid in a polar aprotic solvent with a metal alkoxide solution. The polymer was imidized and the metal oxide formed simultaneously in a refluxing organic solvent. The resulting polymer-metal oxide is an intimately mixed commingled blend, possessing synergistic properties of both the polymer and preceramic metal oxide. The encapsulated metal oxide particles have multiple uses including, being useful in the production of skin lubricating creams, weather resistant paints, as a filler for paper, making ultraviolet light stable filled printing ink, being extruded into fibers or ribbons, and coatings for fibers used in the production of composite structural panels.

Method of making controlled morphology metal-oxides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ozcan, Soydan; Lu, Yuan

2016-05-17

A method of making metal oxides having a preselected morphology includes preparing a suspension that includes a solvent, polymeric nanostructures having multiplicities of hydroxyl surface groups and/or carboxyl surface groups, and a metal oxide precursor. The suspension has a preselected ratio of the polymeric nanostructures to the metal oxide precursor of at least 1:3, the preselected ratio corresponding to a preselected morphology. Subsequent steps include depositing the suspension onto a substrate, removing the solvent to form a film, removing the film from the substrate, and annealing the film to volatilize the polymeric nanostructures and convert the metal oxide precursor tomore » metal oxide nanoparticles having the preselected morphology or to a metal oxide nanosheet including conjoined nanoparticles having the preselected morphology.« less

Bulk-surface relationship of an electronic structure for high-throughput screening of metal oxide catalysts

NASA Astrophysics Data System (ADS)

Kweun, Joshua Minwoo; Li, Chenzhe; Zheng, Yongping; Cho, Maenghyo; Kim, Yoon Young; Cho, Kyeongjae

2016-05-01

Designing metal-oxides consisting of earth-abundant elements has been a crucial issue to replace precious metal catalysts. To achieve efficient screening of metal-oxide catalysts via bulk descriptors rather than surface descriptors, we investigated the relationship between the electronic structure of bulk and that of the surface for lanthanum-based perovskite oxides, LaMO3 (M = Ti, V, Cr, Mn, Fe, Co, Ni, Cu). Through density functional theory calculations, we examined the d-band occupancy of the bulk and surface transition-metal atoms (nBulk and nSurf) and the adsorption energy of an oxygen atom (Eads) on (001), (110), and (111) surfaces. For the (001) surface, we observed strong correlation between the nBulk and nSurf with an R-squared value over 94%, and the result was interpreted in terms of ligand field splitting and antibonding/bonding level splitting. Moreover, the Eads on the surfaces was highly correlated with the nBulk with an R-squared value of more than 94%, and different surface relaxations could be explained by the bulk electronic structure (e.g., LaMnO3 vs. LaTiO3). These results suggest that a bulk-derived descriptor such as nBulk can be used to screen metal-oxide catalysts.

Microbial-mediated method for metal oxide nanoparticle formation

DOEpatents

Rondinone, Adam J.; Moon, Ji Won; Love, Lonnie J.; Yeary, Lucas W.; Phelps, Tommy J.

2015-09-08

The invention is directed to a method for producing metal oxide nanoparticles, the method comprising: (i) subjecting a combination of reaction components to conditions conducive to microbial-mediated formation of metal oxide nanoparticles, wherein said combination of reaction components comprise: metal-reducing microbes, a culture medium suitable for sustaining said metal-reducing microbes, an effective concentration of one or more surfactants, a reducible metal oxide component containing one or more reducible metal species, and one or more electron donors that provide donatable electrons to said metal-reducing microbes during consumption of the electron donor by said metal-reducing microbes; and (ii) isolating said metal oxide nanoparticles, which contain a reduced form of said reducible metal oxide component. The invention is also directed to metal oxide nanoparticle compositions produced by the inventive method.

Approach to Multifunctional Device Platform with Epitaxial Graphene on Transition Metal Oxide (Postprint)

DTIC Science & Technology

2015-09-23

with a metal oxide ( TiO2 ). Our novel direct synthesis of graphene/ TiO2 heterostructure is achieved by C60 deposition on transition Ti metal surface...of TiO2 and C 2p orbitals in the conduction band of graphene enabled by Coulomb interactions at the interface. In addition, this heterostructure...provides a platform for realization of bottom gated graphene field effect devices with graphene and TiO2 playing the roles of channel and gate dielectric

Dendritic core-shell nickel-iron-copper metal/metal oxide electrode for efficient electrocatalytic water oxidation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Peili; Li, Lin; Nordlund, Dennis

Electrochemical water splitting requires efficient water oxidation catalysts to accelerate the sluggish kinetics of water oxidation reaction. Here in this paper, we report a promisingly dendritic core-shell nickel-iron-copper metal/metal oxide electrode, prepared via dealloying with an electrodeposited nickel-iron-copper alloy as a precursor, as the catalyst for water oxidation. The as-prepared core-shell nickel-iron-copper electrode is characterized with porous oxide shells and metallic cores. This tri-metal-based core-shell nickel-iron-copper electrode exhibits a remarkable activity toward water oxidation in alkaline medium with an overpotential of only 180 mV at a current density of 10 mA cm -2. The core-shell NiFeCu electrode exhibits pH-dependent oxygenmore » evolution reaction activity on the reversible hydrogen electrode scale, suggesting that non-concerted proton-electron transfers participate in catalyzing the oxygen evolution reaction. To the best of our knowledge, the as-fabricated core-shell nickel-iron-copper is one of the most promising oxygen evolution catalysts.« less

Dendritic core-shell nickel-iron-copper metal/metal oxide electrode for efficient electrocatalytic water oxidation

DOE PAGES

Zhang, Peili; Li, Lin; Nordlund, Dennis; ...

2018-01-26

Electrochemical water splitting requires efficient water oxidation catalysts to accelerate the sluggish kinetics of water oxidation reaction. Here in this paper, we report a promisingly dendritic core-shell nickel-iron-copper metal/metal oxide electrode, prepared via dealloying with an electrodeposited nickel-iron-copper alloy as a precursor, as the catalyst for water oxidation. The as-prepared core-shell nickel-iron-copper electrode is characterized with porous oxide shells and metallic cores. This tri-metal-based core-shell nickel-iron-copper electrode exhibits a remarkable activity toward water oxidation in alkaline medium with an overpotential of only 180 mV at a current density of 10 mA cm -2. The core-shell NiFeCu electrode exhibits pH-dependent oxygenmore » evolution reaction activity on the reversible hydrogen electrode scale, suggesting that non-concerted proton-electron transfers participate in catalyzing the oxygen evolution reaction. To the best of our knowledge, the as-fabricated core-shell nickel-iron-copper is one of the most promising oxygen evolution catalysts.« less

A metallic metal oxide (Ti5O9)-metal oxide (TiO2) nanocomposite as the heterojunction to enhance visible-light photocatalytic activity

NASA Astrophysics Data System (ADS)

Li, L. H.; Deng, Z. X.; Xiao, J. X.; Yang, G. W.

2015-06-01

Coupling titanium dioxide (TiO2) with other semiconductors is a popular method to extend the optical response range of TiO2 and improve its photon quantum efficiency, as coupled semiconductors can increase the separation rate of photoinduced charge carriers in photocatalysts. Differing from normal semiconductors, metallic oxides have no energy gap separating occupied and unoccupied levels, but they can excite electrons between bands to create a high carrier mobility to facilitate kinetic charge separation. Here, we propose the first metallic metal oxide-metal oxide (Ti5O9-TiO2) nanocomposite as a heterojunction for enhancing the visible-light photocatalytic activity of TiO2 nanoparticles and we demonstrate that this hybridized TiO2-Ti5O9 nanostructure possesses an excellent visible-light photocatalytic performance in the process of photodegrading dyes. The TiO2-Ti5O9 nanocomposites are synthesized in one step using laser ablation in liquid under ambient conditions. The as-synthesized nanocomposites show strong visible-light absorption in the range of 300-800 nm and high visible-light photocatalytic activity in the oxidation of rhodamine B. They also exhibit excellent cycling stability in the photodegrading process. A working mechanism for the metallic metal oxide-metal oxide nanocomposite in the visible-light photocatalytic process is proposed based on first-principle calculations of Ti5O9. This study suggests that metallic metal oxides can be regarded as partners for metal oxide photocatalysts in the construction of heterojunctions to improve photocatalytic activity.

A metallic metal oxide (Ti5O9)-metal oxide (TiO2) nanocomposite as the heterojunction to enhance visible-light photocatalytic activity.

PubMed

Li, L H; Deng, Z X; Xiao, J X; Yang, G W

2015-01-26

Coupling titanium dioxide (TiO2) with other semiconductors is a popular method to extend the optical response range of TiO2 and improve its photon quantum efficiency, as coupled semiconductors can increase the separation rate of photoinduced charge carriers in photocatalysts. Differing from normal semiconductors, metallic oxides have no energy gap separating occupied and unoccupied levels, but they can excite electrons between bands to create a high carrier mobility to facilitate kinetic charge separation. Here, we propose the first metallic metal oxide-metal oxide (Ti5O9-TiO2) nanocomposite as a heterojunction for enhancing the visible-light photocatalytic activity of TiO2 nanoparticles and we demonstrate that this hybridized TiO2-Ti5O9 nanostructure possesses an excellent visible-light photocatalytic performance in the process of photodegrading dyes. The TiO2-Ti5O9 nanocomposites are synthesized in one step using laser ablation in liquid under ambient conditions. The as-synthesized nanocomposites show strong visible-light absorption in the range of 300-800 nm and high visible-light photocatalytic activity in the oxidation of rhodamine B. They also exhibit excellent cycling stability in the photodegrading process. A working mechanism for the metallic metal oxide-metal oxide nanocomposite in the visible-light photocatalytic process is proposed based on first-principle calculations of Ti5O9. This study suggests that metallic metal oxides can be regarded as partners for metal oxide photocatalysts in the construction of heterojunctions to improve photocatalytic activity.

Comparison of effect of 5 MeV proton and Co-60 gamma irradiation on silicon NPN rf power transistors and N-channel depletion MOSFETs

NASA Astrophysics Data System (ADS)

Gnana Prakash, A. P.; Pradeep, T. M.; Hegde, Vinayakprasanna N.; Pushpa, N.; Bajpai, P. K.; Patel, S. P.; Trivedi, Tarkeshwar; Bhushan, K. G.

2017-12-01

NPN transistors and N-channel depletion metal oxide semiconductor field effect transistors (MOSFETs) were irradiated with 5 MeV protons and 60Co gamma radiation in the dose ranging from 1 Mrad(Si) to 100 Mrad(Si). The different electrical characteristics of the NPN transistor such as Gummel characteristics, excess base current (ΔIB), dc current gain (hFE), transconductance (gm), displacement damage factor (K) and output characteristics were studied as a function of total dose. The different electrical characteristics of N-channel MOSFETs such as threshold voltage (Vth), density of interface trapped charges (ΔNit), density of oxide trapped charges (ΔNot), transconductance (gm), mobility (µ) and drain saturation current (IDSat) were studied systematically before and after irradiation in the same dose ranges. A considerable increase in the base current (IB) and decrease in the hFE, gm and collector saturation current (ICSat) were observed after irradiation in the case of the NPN transistor. In the N-channel MOSFETs, the ΔNit and ΔNot were found to increase and Vth, gm, µ and IDSat were found to decrease with increase in the radiation dose. The 5 MeV proton irradiation results of both the NPN transistor and N-channel MOSFETs were compared with 60Co gamma-irradiated devices in the same dose ranges. It was observed that the degradation in 5 MeV proton-irradiated devices is more when compared with the 60Co gamma-irradiated devices at higher total doses.

Methods of producing adsorption media including a metal oxide

DOEpatents

Mann, Nicholas R; Tranter, Troy J

2014-03-04

Methods of producing a metal oxide are disclosed. The method comprises dissolving a metal salt in a reaction solvent to form a metal salt/reaction solvent solution. The metal salt is converted to a metal oxide and a caustic solution is added to the metal oxide/reaction solvent solution to adjust the pH of the metal oxide/reaction solvent solution to less than approximately 7.0. The metal oxide is precipitated and recovered. A method of producing adsorption media including the metal oxide is also disclosed, as is a precursor of an active component including particles of a metal oxide.

Transition-Metal-Controlled Inorganic Ligand-Supported Non-Precious Metal Catalysts for the Aerobic Oxidation of Amines to Imines.

PubMed

Yu, Han; Zhai, Yongyan; Dai, Guoyong; Ru, Shi; Han, Sheng; Wei, Yongge

2017-10-09

Most state-of-art transition-metal catalysts usually require organic ligands, which are essential for controlling the reactivity and selectivity of reactions catalyzed by transition metals. However, organic ligands often suffer from severe problems including cost, toxicity, air/moisture sensitivity, and being commercially unavailable. Herein, we show a simple, mild, and efficient aerobic oxidation procedure of amines using inorganic ligand-supported non-precious metal catalysts 1, (NH 4 ) n [MMo 6 O 18 (OH) 6 ] (M=Cu 2+ ; Fe 3+ ; Co 3+ ; Ni 2+ ; Zn 2+ , n=3 or 4), synthesized by a simple one-step method in water at 100 °C, demonstrating that the catalytic activity and selectivity can be significantly improved by changing the central metal atom. In the presence of these catalysts, the catalytic oxidation of primary and secondary amines, as well as the coupling of alcohols and amines, can smoothly proceed to afford various imines with O 2 (1 atm) as the sole oxidant. In particular, the catalysts 1 have transition-metal ion core, and the planar arrangement of the six Mo VI centers at their highest oxidation states around the central heterometal can greatly enhance the Lewis acidity of catalytically active sites, and also enable the electrons in the center to delocalize onto the six edge-sharing MO 6 units, in the same way as ligands in traditional organometallic complexes. The versatility of this methodology maybe opens a path to catalytic oxidation through inorganic ligand-coordinated metal catalysis. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanostructured transition metal oxides useful for water oxidation catalysis

DOEpatents

Frei, Heinz M; Jiao, Feng

2013-12-24

The present invention provides for a composition comprising a nanostructured transition metal oxide capable of oxidizing two H.sub.2O molecules to obtain four protons. In some embodiments of the invention, the composition further comprises a porous matrix wherein the nanocluster of the transition metal oxide is embedded on and/or in the porous matrix.

Direct imprinting of indium-tin-oxide precursor gel and simultaneous formation of channel and source/drain in thin-film transistor

NASA Astrophysics Data System (ADS)

Haga, Ken-ichi; Kamiya, Yuusuke; Tokumitsu, Eisuke

2018-02-01

We report on a new fabrication process for thin-film transistors (TFTs) with a new structure and a new operation principle. In this process, both the channel and electrode (source/drain) are formed simultaneously, using the same oxide material, using a single nano-rheology printing (n-RP) process, without any conventional lithography process. N-RP is a direct thermal imprint technique and deforms oxide precursor gel. To reduce the source/drain resistance, the material common to the channel and electrode is conductive indium-tin-oxide (ITO). The gate insulator is made of a ferroelectric material, whose high charge density can deplete the channel of the thin ITO film, which realizes the proposed operation principle. First, we have examined the n-RP conditions required for the channel and source/drain patterning, and found that the patterning properties are strongly affected by the cooling rate before separating the mold. Second, we have fabricated the TFTs as proposed and confirmed their TFT operation.

Systematic study of metal-insulator-metal diodes with a native oxide

NASA Astrophysics Data System (ADS)

Donchev, E.; Gammon, P. M.; Pang, J. S.; Petrov, P. K.; Alford, N. McN.

2014-10-01

In this paper, a systematic analysis of native oxides within a Metal-Insulator-Metal (MIM) diode is carried out, with the goal of determining their practicality for incorporation into a nanoscale Rectenna (Rectifying Antenna). The requirement of having a sub-10nm oxide scale is met by using the native oxide, which forms on most metals exposed to an oxygen containing environment. This, therefore, provides a simplified MIM fabrication process as the complex, controlled oxide deposition step is omitted. We shall present the results of an investigation into the current-voltage characteristics of various MIM combinations that incorporate a native oxide, in order to establish whether the native oxide is of sufficient quality for good diode operation. The thin native oxide layers are formed by room temperature oxidation of the first metal layer, deposited by magnetron sputtering. This is done in-situ, within the deposition chamber before depositing the second metal electrode. Using these structures, we study the established trend where the bigger the difference in metal workfunctions, the better the rectification properties of MIM structures, and hence the selection of the second metal is key to controlling the device's rectifying properties. We show how leakage current paths through the non-optimised native oxide control the net current-voltage response of the MIM devices. Furthermore, we will present the so-called diode figures of merit (asymmetry, non-linearity and responsivity) for each of the best performing structures.

Oxidized film structure and method of making epitaxial metal oxide structure

DOEpatents

Gan, Shupan [Richland, WA; Liang, Yong [Richland, WA

2003-02-25

A stable oxidized structure and an improved method of making such a structure, including an improved method of making an interfacial template for growing a crystalline metal oxide structure, are disclosed. The improved method comprises the steps of providing a substrate with a clean surface and depositing a metal on the surface at a high temperature under a vacuum to form a metal-substrate compound layer on the surface with a thickness of less than one monolayer. The compound layer is then oxidized by exposing the compound layer to essentially oxygen at a low partial pressure and low temperature. The method may further comprise the step of annealing the surface while under a vacuum to further stabilize the oxidized film structure. A crystalline metal oxide structure may be subsequently epitaxially grown by using the oxidized film structure as an interfacial template and depositing on the interfacial template at least one layer of a crystalline metal oxide.

Considerably improved photovoltaic performance of carbon nanotube-based solar cells using metal oxide layers.

PubMed

Wang, Feijiu; Kozawa, Daichi; Miyauchi, Yuhei; Hiraoka, Kazushi; Mouri, Shinichiro; Ohno, Yutaka; Matsuda, Kazunari

2015-02-18

Carbon nanotube-based solar cells have been extensively studied from the perspective of potential application. Here we demonstrated a significant improvement of the carbon nanotube solar cells by the use of metal oxide layers for efficient carrier transport. The metal oxides also serve as an antireflection layer and an efficient carrier dopant, leading to a reduction in the loss of the incident solar light and an increase in the photocurrent, respectively. As a consequence, the photovoltaic performance of both p-single-walled carbon nanotube (SWNT)/n-Si and n-SWNT/p-Si heterojunction solar cells using MoOx and ZnO layers is improved, resulting in very high photovoltaic conversion efficiencies of 17.0 and 4.0%, respectively. These findings regarding the use of metal oxides as multifunctional layers suggest that metal oxide layers could improve the performance of various electronic devices based on carbon nanotubes.

Considerably improved photovoltaic performance of carbon nanotube-based solar cells using metal oxide layers

NASA Astrophysics Data System (ADS)

Wang, Feijiu; Kozawa, Daichi; Miyauchi, Yuhei; Hiraoka, Kazushi; Mouri, Shinichiro; Ohno, Yutaka; Matsuda, Kazunari

2015-02-01

Carbon nanotube-based solar cells have been extensively studied from the perspective of potential application. Here we demonstrated a significant improvement of the carbon nanotube solar cells by the use of metal oxide layers for efficient carrier transport. The metal oxides also serve as an antireflection layer and an efficient carrier dopant, leading to a reduction in the loss of the incident solar light and an increase in the photocurrent, respectively. As a consequence, the photovoltaic performance of both p-single-walled carbon nanotube (SWNT)/n-Si and n-SWNT/p-Si heterojunction solar cells using MoOx and ZnO layers is improved, resulting in very high photovoltaic conversion efficiencies of 17.0 and 4.0%, respectively. These findings regarding the use of metal oxides as multifunctional layers suggest that metal oxide layers could improve the performance of various electronic devices based on carbon nanotubes.

Conducting metal oxide and metal nitride nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

DiSalvo, Jr., Francis J.; Subban, Chinmayee V.

Conducting metal oxide and nitride nanoparticles that can be used in fuel cell applications. The metal oxide nanoparticles are comprised of for example, titanium, niobium, tantalum, tungsten and combinations thereof. The metal nitride nanoparticles are comprised of, for example, titanium, niobium, tantalum, tungsten, zirconium, and combinations thereof. The nanoparticles can be sintered to provide conducting porous agglomerates of the nanoparticles which can be used as a catalyst support in fuel cell applications. Further, platinum nanoparticles, for example, can be deposited on the agglomerates to provide a material that can be used as both an anode and a cathode catalyst supportmore » in a fuel cell.« less

INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Quantum-Mechanical Study on Surrounding-Gate Metal-Oxide-Semiconductor Field-Effect Transistors

NASA Astrophysics Data System (ADS)

Hu, Guang-Xi; Wang, Ling-Li; Liu, Ran; Tang, Ting-Ao; Qiu, Zhi-Jun

2010-10-01

As the channel length of metal-oxide-semiconductor field-effect transistors (MOSFETs) scales into the nanometer regime, quantum mechanical effects are becoming more and more significant. In this work, a model for the surrounding-gate (SG) nMOSFET is developed. The Schrödinger equation is solved analytically. Some of the solutions are verified via results obtained from simulations. It is found that the percentage of the electrons with lighter conductivity mass increases as the silicon body radius decreases, or as the gate voltage reduces, or as the temperature decreases. The centroid of inversion-layer is driven away from the silicon-oxide interface towards the silicon body, therefore the carriers will suffer less scattering from the interface and the electrons effective mobility of the SG nMOSFETs will be enhanced.

Single channel double-duct liquid metal electrical generator using a magnetohydrodynamic device

DOEpatents

Haaland, C.M.; Deeds, W.E.

1999-07-13

A single channel double-duct liquid metal electrical generator using a magnetohydrodynamic (MHD) device. The single channel device provides useful output AC electric energy. The generator includes a two-cylinder linear-piston engine which drives liquid metal in a single channel looped around one side of the MHD device to form a double-duct contra-flowing liquid metal MHD generator. A flow conduit network and drive mechanism are provided for moving liquid metal with an oscillating flow through a static magnetic field to produce useful AC electric energy at practical voltages and currents. Variable stroke is obtained by controlling the quantity of liquid metal in the channel. High efficiency is obtained over a wide range of frequency and power output. 5 figs.

Single channel double-duct liquid metal electrical generator using a magnetohydrodynamic device

DOEpatents

Haaland, Carsten M.; Deeds, W. Edward

1999-01-01

A single channel double-duct liquid metal electrical generator using a magnetohydrodynamic (MHD) device. The single channel device provides useful output AC electric energy. The generator includes a two-cylinder linear-piston engine which drives liquid metal in a single channel looped around one side of the MHD device to form a double-duct contra-flowing liquid metal MHD generator. A flow conduit network and drive mechanism are provided for moving liquid metal with an oscillating flow through a static magnetic field to produce useful AC electric energy at practical voltages and currents. Variable stroke is obtained by controlling the quantity of liquid metal in the channel. High efficiency is obtained over a wide range of frequency and power output.

Process for producing metal compounds from graphite oxide

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh (Inventor)

2000-01-01

A process for providing elemental metals or metal oxides distributed on a carbon substrate or self-supported utilizing graphite oxide as a precursor. The graphite oxide is exposed to one or more metal chlorides to form an intermediary product comprising carbon, metal, chloride, and oxygen This intermediary product can be flier processed by direct exposure to carbonate solutions to form a second intermediary product comprising carbon, metal carbonate, and oxygen. Either intermediary product may be further processed: a) in air to produce metal oxide; b) in an inert environment to produce metal oxide on carbon substrate; c) in a reducing environment to produce elemental metal distributed on carbon substrate. The product generally takes the shape of the carbon precursor.

Process for Producing Metal Compounds from Graphite Oxide

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh (Inventor)

2000-01-01

A process for providing elemental metals or metal oxides distributed on a carbon substrate or self-supported utilizing graphite oxide as a precursor. The graphite oxide is exposed to one or more metal chlorides to form an intermediary product comprising carbon. metal. chloride. and oxygen This intermediary product can be flier processed by direct exposure to carbonate solutions to form a second intermediary product comprising carbon. metal carbonate. and oxygen. Either intermediary product may be further processed: a) in air to produce metal oxide: b) in an inert environment to produce metal oxide on carbon substrate: c) in a reducing environment. to produce elemental metal distributed on carbon substrate. The product generally takes the shape of the carbon precursor.

High surface area, electrically conductive nanocarbon-supported metal oxide

DOEpatents

Worsley, Marcus A.; Han, Thomas Yong-Jin; Kuntz, Joshua D.; Cervantes, Octavio; Gash, Alexander E.; Baumann, Theodore F.; Satcher, Jr., Joe H.

2015-07-14

A metal oxide-carbon composite includes a carbon aerogel with an oxide overcoat. The metal oxide-carbon composite is made by providing a carbon aerogel, immersing the carbon aerogel in a metal oxide sol under a vacuum, raising the carbon aerogel with the metal oxide sol to atmospheric pressure, curing the carbon aerogel with the metal oxide sol at room temperature, and drying the carbon aerogel with the metal oxide sol to produce the metal oxide-carbon composite. The step of providing a carbon aerogel can provide an activated carbon aerogel or provide a carbon aerogel with carbon nanotubes that make the carbon aerogel mechanically robust.

High surface area, electrically conductive nanocarbon-supported metal oxide

DOEpatents

Worsley, Marcus A; Han, Thomas Yong-Jin; Kuntz, Joshua D; Cervanted, Octavio; Gash, Alexander E; Baumann, Theodore F; Satcher, Jr., Joe H

2014-03-04

A metal oxide-carbon composite includes a carbon aerogel with an oxide overcoat. The metal oxide-carbon composite is made by providing a carbon aerogel, immersing the carbon aerogel in a metal oxide sol under a vacuum, raising the carbon aerogel with the metal oxide sol to atmospheric pressure, curing the carbon aerogel with the metal oxide sol at room temperature, and drying the carbon aerogel with the metal oxide sol to produce the metal oxide-carbon composite. The step of providing a carbon aerogel can provide an activated carbon aerogel or provide a carbon aerogel with carbon nanotubes that make the carbon aerogel mechanically robust.

Reduction of spalling in mixed metal oxide desulfurization sorbents by addition of a large promoter metal oxide

DOEpatents

Poston, J.A.

1997-12-02

Mixed metal oxide pellets for removing hydrogen sulfide from fuel gas mixes derived from coal are stabilized for operation over repeated cycles of desulfurization and regeneration reactions by addition of a large promoter metal oxide such as lanthanum trioxide. The pellets, which may be principally made up of a mixed metal oxide such as zinc titanate, exhibit physical stability and lack of spalling or decrepitation over repeated cycles without loss of reactivity. The lanthanum oxide is mixed with pellet-forming components in an amount of 1 to 10 weight percent.

Reduction of spalling in mixed metal oxide desulfurization sorbents by addition of a large promoter metal oxide

DOEpatents

Poston, James A.

1997-01-01

Mixed metal oxide pellets for removing hydrogen sulfide from fuel gas mixes derived from coal are stabilized for operation over repeated cycles of desulfurization and regeneration reactions by addition of a large promoter metal oxide such as lanthanum trioxide. The pellets, which may be principally made up of a mixed metal oxide such as zinc titanate, exhibit physical stability and lack of spalling or decrepitation over repeated cycles without loss of reactivity. The lanthanum oxide is mixed with pellet-forming components in an amount of 1 to 10 weight percent.

Role of Oxidative Stress in Transformation Induced by Metal Mixture

PubMed Central

Martín, Silva-Aguilar; Emilio, Rojas; Mahara, Valverde

2011-01-01

Metals are ubiquitous pollutants present as mixtures. In particular, mixture of arsenic-cadmium-lead is among the leading toxic agents detected in the environment. These metals have carcinogenic and cell-transforming potential. In this study, we used a two step cell transformation model, to determine the role of oxidative stress in transformation induced by a mixture of arsenic-cadmium-lead. Oxidative damage and antioxidant response were determined. Metal mixture treatment induces the increase of damage markers and the antioxidant response. Loss of cell viability and increased transforming potential were observed during the promotion phase. This finding correlated significantly with generation of reactive oxygen species. Cotreatment with N-acetyl-cysteine induces effect on the transforming capacity; while a diminution was found in initiation, in promotion phase a total block of the transforming capacity was observed. Our results suggest that oxidative stress generated by metal mixture plays an important role only in promotion phase promoting transforming capacity. PMID:22191014

Minimal proton channel enables H2 oxidation and production with a water-soluble nickel-based catalyst.

PubMed

Dutta, Arnab; Lense, Sheri; Hou, Jianbo; Engelhard, Mark H; Roberts, John A S; Shaw, Wendy J

2013-12-11

Hydrogenase enzymes use first-row transition metals to interconvert H2 with protons and electrons, reactions that are important for the storage and recovery of energy from intermittent sources such as solar, hydroelectric, and wind. Here we present Ni(P(Cy)2N(Gly)2)2, a water-soluble molecular electrocatalyst with the amino acid glycine built into the diphosphine ligand framework. Proton transfer between the outer coordination sphere carboxylates and the second coordination sphere pendant amines is rapid, as observed by cyclic voltammetry and FTIR spectroscopy, indicating that the carboxylate groups may participate in proton transfer during catalysis. This complex oxidizes H2 (1-33 s(-1)) at low overpotentials (150-365 mV) over a range of pH values (0.1-9.0) and produces H2 under identical solution conditions (>2400 s(-1) at pH 0.5). Enzymes employ proton channels for the controlled movement of protons over long distances-the results presented here demonstrate the effects of a simple two-component proton channel in a synthetic molecular electrocatalyst.

Ge{sub 0.83}Sn{sub 0.17} p-channel metal-oxide-semiconductor field-effect transistors: Impact of sulfur passivation on gate stack quality

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lei, Dian; Wang, Wei; Gong, Xiao, E-mail: elegong@nus.edu.sg, E-mail: yeo@ieee.org

2016-01-14

The effect of room temperature sulfur passivation of the surface of Ge{sub 0.83}Sn{sub 0.17} prior to high-k dielectric (HfO{sub 2}) deposition is investigated. X-ray photoelectron spectroscopy (XPS) was used to examine the chemical bonding at the interface of HfO{sub 2} and Ge{sub 0.83}Sn{sub 0.17}. Sulfur passivation is found to be effective in suppressing the formation of both Ge oxides and Sn oxides. A comparison of XPS results for sulfur-passivated and non-passivated Ge{sub 0.83}Sn{sub 0.17} samples shows that sulfur passivation of the GeSn surface could also suppress the surface segregation of Sn atoms. In addition, sulfur passivation reduces the interface trapmore » density D{sub it} at the high-k dielectric/Ge{sub 0.83}Sn{sub 0.17} interface from the valence band edge to the midgap of Ge{sub 0.83}Sn{sub 0.17}, as compared with a non-passivated control. The impact of the improved D{sub it} is demonstrated in Ge{sub 0.83}Sn{sub 0.17} p-channel metal-oxide-semiconductor field-effect transistors (p-MOSFETs). Ge{sub 0.83}Sn{sub 0.17} p-MOSFETs with sulfur passivation show improved subthreshold swing S, intrinsic transconductance G{sub m,int}, and effective hole mobility μ{sub eff} as compared with the non-passivated control. At a high inversion carrier density N{sub inv} of 1 × 10{sup 13 }cm{sup −2}, sulfur passivation increases μ{sub eff} by 25% in Ge{sub 0.83}Sn{sub 0.17} p-MOSFETs.« less

Quantum Mechanical Studies of Large Metal, Metal Oxide, and Metal Chalcogenide Nanoparticles and Clusters

DOE PAGES

Fernando, Amendra; Weerawardene, K. L. Dimuthu M.; Karimova, Natalia V.; ...

2015-04-21

Here, metal, metal oxide, and metal chalcogenide materials have a wide variety of applications. For example, many metal clusters and nanoparticles are used as catalysts for reactions varying from the oxidation of carbon monoxide to the reduction of protons to hydrogen gas. Noble metal nanoparticles have unique optical properties such as a surface plasmon resonance for large nanoparticles that yield applications in sensing and photonics. In addition, a number of transition metal clusters are magnetic. Metal oxide clusters and surfaces are commonly used as catalysts for reactions such as water splitting. Both metal oxide and metal chalcogenide materials can bemore » semiconducting, which leads to applications in sensors, electronics, and solar cells. Many researchers have been interested in studying nanoparticles and/or small clusters of these materials. Some of the system sizes under investigation have been experimentally synthesized, which enables direct theory–experiment comparison. Other clusters that have been examined theoretically are of interest as models of larger systems or surfaces. Often, the size-dependence of their properties such as their HOMO–LUMO gap, magnetic properties, optical properties, etc., is of interest.« less

Models of second-order effects in metal-oxide-semiconductor field-effect transistors for computer applications

NASA Technical Reports Server (NTRS)

Benumof, Reuben; Zoutendyk, John; Coss, James

1988-01-01

Second-order effects in metal-oxide-semiconductor field-effect transistors (MOSFETs) are important for devices with dimensions of 2 microns or less. The short and narrow channel effects and drain-induced barrier lowering primarily affect threshold voltage, but formulas for drain current must also take these effects into account. In addition, the drain current is sensitive to channel length modulation due to pinch-off or velocity saturation and is diminished by electron mobility degradation due to normal and lateral electric fields in the channel. A model of a MOSFET including these considerations and emphasizing charge conservation is discussed.

Oxidation-Mediated Fingering in Liquid Metals

NASA Astrophysics Data System (ADS)

Eaker, Collin B.; Hight, David C.; O'Regan, John D.; Dickey, Michael D.; Daniels, Karen E.

2017-10-01

We identify and characterize a new class of fingering instabilities in liquid metals; these instabilities are unexpected due to the large interfacial tension of metals. Electrochemical oxidation lowers the effective interfacial tension of a gallium-based liquid metal alloy to values approaching zero, thereby inducing drastic shape changes, including the formation of fractals. The measured fractal dimension (D =1.3 ±0.05 ) places the instability in a different universality class than other fingering instabilities. By characterizing changes in morphology and dynamics as a function of droplet volume and applied electric potential, we identify the three main forces involved in this process: interfacial tension, gravity, and oxidative stress. Importantly, we find that electrochemical oxidation can generate compressive interfacial forces that oppose the tensile forces at a liquid interface. The surface oxide layer ultimately provides a physical and electrochemical barrier that halts the instabilities at larger positive potentials. Controlling the competition between interfacial tension and oxidative (compressive) stresses at the interface is important for the development of reconfigurable electronic, electromagnetic, and optical devices that take advantage of the metallic properties of liquid metals.

40 CFR 721.5549 - Lithiated metal oxide.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Lithiated metal oxide. 721.5549... Substances § 721.5549 Lithiated metal oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as lithiated metal oxide (LiNiO2) (PMN P-96-19...

40 CFR 721.5549 - Lithiated metal oxide.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Lithiated metal oxide. 721.5549... Substances § 721.5549 Lithiated metal oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as lithiated metal oxide (LiNiO2) (PMN P-96-19...

Effect of proton irradiation dose on InAlN/GaN metal-oxide semiconductor high electron mobility transistors with Al 2O 3 gate oxide

DOE PAGES

Ahn, Shihyun; Kim, Byung -Jae; Lin, Yi -Hsuan; ...

2016-07-26

The effects of proton irradiation on the dc performance of InAlN/GaN metal-oxide-semiconductor high electron mobility transistors (MOSHEMTs) with Al 2O 3 as the gate oxide were investigated. The InAlN/GaN MOSHEMTs were irradiated with doses ranging from 1×10 13 to 1×10 15cm –2 at a fixed energy of 5MeV. There was minimal damage induced in the two dimensional electron gas at the lowest irradiation dose with no measurable increase in sheet resistance, whereas a 9.7% increase of the sheet resistance was observed at the highest irradiation dose. By sharp contrast, all irradiation doses created more severe degradation in the Ohmic metalmore » contacts, with increases of specific contact resistance from 54% to 114% over the range of doses investigated. These resulted in source-drain current–voltage decreases ranging from 96 to 242 mA/mm over this dose range. The trap density determined from temperature dependent drain current subthreshold swing measurements increased from 1.6 × 10 13 cm –2 V –1 for the reference MOSHEMTs to 6.7 × 10 13 cm –2 V –1 for devices irradiated with the highest dose. In conclusion, the carrier removal rate was 1287 ± 64 cm –1, higher than the authors previously observed in AlGaN/GaN MOSHEMTs for the same proton energy and consistent with the lower average bond energy of the InAlN.« less

Leakage current conduction in metal gate junctionless nanowire transistors

NASA Astrophysics Data System (ADS)

Oproglidis, T. A.; Karatsori, T. A.; Barraud, S.; Ghibaudo, G.; Dimitriadis, C. A.

2017-05-01

In this paper, the experimental off-state drain leakage current behavior is systematically explored in n- and p-channel junctionless nanowire transistors with HfSiON/TiN/p+-polysilicon gate stack. The analysis of the drain leakage current is based on experimental data of the gate leakage current. It has been shown that the off-state drain leakage current in n-channel devices is negligible, whereas in p-channel devices it is significant and dramatically increases with drain voltage. The overall results indicate that the off-state drain leakage current in p-channel devices is mainly due to trap-assisted Fowler-Nordheim tunneling of electrons through the gate oxide of electrons from the metal gate to the silicon layer near the drain region.

High temperature, oxidation resistant noble metal-Al alloy thermocouple

NASA Technical Reports Server (NTRS)

Smialek, James L. (Inventor); Gedwill, Michael G. (Inventor)

1994-01-01

A thermocouple is disclosed. The thermocouple is comprised of an electropositive leg formed of a noble metal-Al alloy and an electronegative leg electrically joined to form a thermocouple junction. The thermocouple provides for accurate and reproducible measurement of high temperatures (600 - 1300 C) in inert, oxidizing or reducing environments, gases, or vacuum. Furthermore, the thermocouple circumvents the need for expensive, strategic precious metals such as rhodium as a constituent component. Selective oxidation of rhodium is also thereby precluded.

Silicon carbide: A unique platform for metal-oxide-semiconductor physics

NASA Astrophysics Data System (ADS)

Liu, Gang; Tuttle, Blair R.; Dhar, Sarit

2015-06-01

A sustainable energy future requires power electronics that can enable significantly higher efficiencies in the generation, distribution, and usage of electrical energy. Silicon carbide (4H-SiC) is one of the most technologically advanced wide bandgap semiconductor that can outperform conventional silicon in terms of power handling, maximum operating temperature, and power conversion efficiency in power modules. While SiC Schottky diode is a mature technology, SiC power Metal Oxide Semiconductor Field Effect Transistors are relatively novel and there is large room for performance improvement. Specifically, major initiatives are under way to improve the inversion channel mobility and gate oxide stability in order to further reduce the on-resistance and enhance the gate reliability. Both problems relate to the defects near the SiO2/SiC interface, which have been the focus of intensive studies for more than a decade. Here we review research on the SiC MOS physics and technology, including its brief history, the state-of-art, and the latest progress in this field. We focus on the two main scientific problems, namely, low channel mobility and bias temperature instability. The possible mechanisms behind these issues are discussed at the device physics level as well as the atomic scale, with the support of published physical analysis and theoretical studies results. Some of the most exciting recent progress in interface engineering for improving the channel mobility and fundamental understanding of channel transport is reviewed.

Low temperature mobility in hafnium-oxide gated germanium p-channel metal-oxide-semiconductor field-effect transistors

NASA Astrophysics Data System (ADS)

Beer, Chris; Whall, Terry; Parker, Evan; Leadley, David; De Jaeger, Brice; Nicholas, Gareth; Zimmerman, Paul; Meuris, Marc; Szostak, Slawomir; Gluszko, Grzegorz; Lukasiak, Lidia

2007-12-01

Effective mobility measurements have been made at 4.2K on high performance high-k gated germanium p-type metal-oxide-semiconductor field effect transistors with a range of Ge/gate dielectric interface state densities. The mobility is successfully modelled by assuming surface roughness and interface charge scattering at the SiO2 interlayer/Ge interface. The deduced interface charge density is approximately equal to the values obtained from the threshold voltage and subthreshold slope measurements on each device. A hydrogen anneal reduces both the interface state density and the surface root mean square roughness by 20%.

AlN and Al oxy-nitride gate dielectrics for reliable gate stacks on Ge and InGaAs channels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Y.; Li, H.; Robertson, J.

2016-05-28

AlN and Al oxy-nitride dielectric layers are proposed instead of Al{sub 2}O{sub 3} as a component of the gate dielectric stacks on higher mobility channels in metal oxide field effect transistors to improve their positive bias stress instability reliability. It is calculated that the gap states of nitrogen vacancies in AlN lie further away in energy from the semiconductor band gap than those of oxygen vacancies in Al{sub 2}O{sub 3}, and thus AlN might be less susceptible to charge trapping and have a better reliability performance. The unfavourable defect energy level distribution in amorphous Al{sub 2}O{sub 3} is attributed tomore » its larger coordination disorder compared to the more symmetrically bonded AlN. Al oxy-nitride is also predicted to have less tendency for charge trapping.« less

Metal oxide semiconductor thin-film transistors for flexible electronics

NASA Astrophysics Data System (ADS)

Petti, Luisa; Münzenrieder, Niko; Vogt, Christian; Faber, Hendrik; Büthe, Lars; Cantarella, Giuseppe; Bottacchi, Francesca; Anthopoulos, Thomas D.; Tröster, Gerhard

2016-06-01

The field of flexible electronics has rapidly expanded over the last decades, pioneering novel applications, such as wearable and textile integrated devices, seamless and embedded patch-like systems, soft electronic skins, as well as imperceptible and transient implants. The possibility to revolutionize our daily life with such disruptive appliances has fueled the quest for electronic devices which yield good electrical and mechanical performance and are at the same time light-weight, transparent, conformable, stretchable, and even biodegradable. Flexible metal oxide semiconductor thin-film transistors (TFTs) can fulfill all these requirements and are therefore considered the most promising technology for tomorrow's electronics. This review reflects the establishment of flexible metal oxide semiconductor TFTs, from the development of single devices, large-area circuits, up to entirely integrated systems. First, an introduction on metal oxide semiconductor TFTs is given, where the history of the field is revisited, the TFT configurations and operating principles are presented, and the main issues and technological challenges faced in the area are analyzed. Then, the recent advances achieved for flexible n-type metal oxide semiconductor TFTs manufactured by physical vapor deposition methods and solution-processing techniques are summarized. In particular, the ability of flexible metal oxide semiconductor TFTs to combine low temperature fabrication, high carrier mobility, large frequency operation, extreme mechanical bendability, together with transparency, conformability, stretchability, and water dissolubility is shown. Afterward, a detailed analysis of the most promising metal oxide semiconducting materials developed to realize the state-of-the-art flexible p-type TFTs is given. Next, the recent progresses obtained for flexible metal oxide semiconductor-based electronic circuits, realized with both unipolar and complementary technology, are reported. In particular

Metal oxide semiconductor thin-film transistors for flexible electronics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petti, Luisa; Vogt, Christian; Büthe, Lars

The field of flexible electronics has rapidly expanded over the last decades, pioneering novel applications, such as wearable and textile integrated devices, seamless and embedded patch-like systems, soft electronic skins, as well as imperceptible and transient implants. The possibility to revolutionize our daily life with such disruptive appliances has fueled the quest for electronic devices which yield good electrical and mechanical performance and are at the same time light-weight, transparent, conformable, stretchable, and even biodegradable. Flexible metal oxide semiconductor thin-film transistors (TFTs) can fulfill all these requirements and are therefore considered the most promising technology for tomorrow's electronics. This reviewmore » reflects the establishment of flexible metal oxide semiconductor TFTs, from the development of single devices, large-area circuits, up to entirely integrated systems. First, an introduction on metal oxide semiconductor TFTs is given, where the history of the field is revisited, the TFT configurations and operating principles are presented, and the main issues and technological challenges faced in the area are analyzed. Then, the recent advances achieved for flexible n-type metal oxide semiconductor TFTs manufactured by physical vapor deposition methods and solution-processing techniques are summarized. In particular, the ability of flexible metal oxide semiconductor TFTs to combine low temperature fabrication, high carrier mobility, large frequency operation, extreme mechanical bendability, together with transparency, conformability, stretchability, and water dissolubility is shown. Afterward, a detailed analysis of the most promising metal oxide semiconducting materials developed to realize the state-of-the-art flexible p-type TFTs is given. Next, the recent progresses obtained for flexible metal oxide semiconductor-based electronic circuits, realized with both unipolar and complementary technology, are reported. In

Design and Development of Mixed-Metal Oxide Photocatalysts: the Band Engineering Approach

NASA Astrophysics Data System (ADS)

Boltersdorf, Jonathan Andrew

The design and development of mixed-metal oxides incorporating Ag(I), Pb(II), Sn(II), and Bi(III), i.e., with filled d10 or d10s2 electron configurations, have yielded new approaches to tune optical and photocatalytic properties for solar energy conversion. My research efforts in the area of solid-state photochemistry have focused on utilizing flux-mediated ion-exchange methods in conjunction with the band engineering approach to synthesize new materials for solar energy driven total water splitting. Layered perovskite phases and the polysomatic family of tantalate/niobate structures, with the general formula Am+ ( n+1)/mB(3 n+1)O(8n +3) (A = Na, Ag; B = Ta, Nb), have received increasing attention owing to their synthetic flexibility, tunable optical band gaps, and photocatalytic activities for total water splitting. Structures in the family of A m+ (n+1)/ mB(3n +1)O(8n+3) structures are based on the stacking of pentagonal bipyramidal layers, where n defines the average thickness (1 ≤ n ≤ 2) of the BO7 layers that alternate with isolated BO6 octahedra surrounded by A-site cations. Synthetic limitations in the discovery of new phases within the layered perovskites and the Am + (n+1)/mB(3 n+1)O(8n +3) structural families can be addressed with the aid of a metal-salt solvent, known as the molten-salt flux method. The flux synthetic route requires the use of an inorganic salt heated above its melting temperature in order to serve as a solvent system for crystallization. Molten fluxes allow for synthetic modification of particle characteristics and can enable the low temperature stabilization of new compositions and phases with limited stability using ion-exchange reactions (e.g., PbTa4O11, AgLaNb 2O7). Solid-state and flux-mediated exchange methods were utilized in order to synthetically explore and investigate the layered perovskites ALaNb2O7, AA2Nb3O 10, A'2La2Ti3O10 (A' = Rb, Ag; A = Ca, Sr), the Am+ (n+1)/mB 3n+1O(8 n+3) structural family (Am + = Na(I), Ag

Unified computational model of transport in metal-insulating oxide-metal systems

NASA Astrophysics Data System (ADS)

Tierney, B. D.; Hjalmarson, H. P.; Jacobs-Gedrim, R. B.; Agarwal, Sapan; James, C. D.; Marinella, M. J.

2018-04-01

A unified physics-based model of electron transport in metal-insulator-metal (MIM) systems is presented. In this model, transport through metal-oxide interfaces occurs by electron tunneling between the metal electrodes and oxide defect states. Transport in the oxide bulk is dominated by hopping, modeled as a series of tunneling events that alter the electron occupancy of defect states. Electron transport in the oxide conduction band is treated by the drift-diffusion formalism and defect chemistry reactions link all the various transport mechanisms. It is shown that the current-limiting effect of the interface band offsets is a function of the defect vacancy concentration. These results provide insight into the underlying physical mechanisms of leakage currents in oxide-based capacitors and steady-state electron transport in resistive random access memory (ReRAM) MIM devices. Finally, an explanation of ReRAM bipolar switching behavior based on these results is proposed.

Metal oxide composite dosimeter method and material

DOEpatents

Miller, Steven D.

1998-01-01

The present invention is a method of measuring a radiation dose wherein a radiation responsive material consisting essentially of metal oxide is first exposed to ionizing radiation. The metal oxide is then stimulating with light thereby causing the radiation responsive material to photoluminesce. Photons emitted from the metal oxide as a result of photoluminescence may be counted to provide a measure of the ionizing radiation.

Photoelectron spectroscopy of the bis(dithiolene) anions [M(mnt)2]n- (M = Fe - Zn; n = 1, 2): changes in electronic structure with variation of metal center and with oxidation.

PubMed

Waters, Tom; Wang, Xue-Bin; Woo, Hin-Koon; Wang, Lai-Sheng

2006-07-24

A detailed understanding of the electronic structures of transition metal bis(dithiolene) centers is important in the context of their interesting redox, magnetic, and optical properties. The electronic structures of the series [M(mnt)2]n- (M = Fe - Zn; mnt = 1,2-S2C2(CN)2; n = 1, 2) were examined by a combination of photodetachment photoelectron spectroscopy and density functional theory calculations, providing insights into changes in electronic structure with variation of the metal center and with oxidation. Significant changes were observed for the dianions [M(mnt)2]2- due to stabilization of the metal 3d levels from Fe to Zn and the transition from square-planar to tetrahedral coordination about the metal center (Fe-Ni, D(2h) --> Cu D2 --> Zn, D(2d). Changes with oxidation from [M(mnt)2]2- to [M(mnt)2]1- were largely dependent on the nature of the redox-active orbital in the couple [M(mnt)2](2-/1-). In particular, the first detachment feature for [Fe(mnt)2]2- originated from a metal-based orbital (Fe(II) --> Fe(III)) while that for [Fe(mnt)2]1- originated from a ligand-based orbital, a consequence of stabilization of Fe 3d levels in the latter. In contrast, the first detachment feature for both of [Ni(mnt)2]2- and [Ni(mnt)2]1- originated from the same ligand-based orbital in both cases, a result of occupied Ni 3d levels being stabilized relative those of Fe 3d and occurring below the highest energy occupied ligand-based orbital for both of [Ni(mnt)2]2- and [Ni(mnt)2]1- . The combined data illustrate the subtle interplay between metal- and ligand-based redox chemistry in these species and demonstrate changes in their electronic structures with variation of metal center, oxidation, and coordination geometry.

Carbon monoxide oxidation over three different states of copper: Development of a model metal oxide catalyst

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jernigan, Glenn Geoffrey

1994-10-01

Carbon monoxide oxidation was performed over the three different oxidation states of copper -- metallic (Cu), copper (I) oxide (Cu 2O), and copper (II) oxide (CuO) as a test case for developing a model metal oxide catalyst amenable to study by the methods of modern surface science and catalysis. Copper was deposited and oxidized on oxidized supports of aluminum, silicon, molybdenum, tantalum, stainless steel, and iron as well as on graphite. The catalytic activity was found to decrease with increasing oxidation state (Cu > Cu 2O > CuO) and the activation energy increased with increasing oxidation state (Cu, 9 kcal/molmore » < Cu 2O, 14 kcal/mol < CuO, 17 kcal/mol). Reaction mechanisms were determined for the different oxidation states. Lastly, NO reduction by CO was studied. A Cu and CuO catalyst were exposed to an equal mixture of CO and NO at 300--350 C to observe the production of N 2 and CO 2. At the end of each reaction, the catalyst was found to be Cu 2O. There is a need to study the kinetics of this reaction over the different oxidation states of copper.« less

Interfacial Metal-Oxide Interactions in Resistive Switching Memories.

PubMed

Cho, Deok-Yong; Luebben, Michael; Wiefels, Stefan; Lee, Kug-Seung; Valov, Ilia

2017-06-07

Metal oxides are commonly used as electrolytes for redox-based resistive switching memories. In most cases, non-noble metals are directly deposited as ohmic electrodes. We demonstrate that irrespective of bulk thermodynamics predictions an intermediate oxide film a few nanometers in thickness is always formed at the metal/insulator interface, and this layer significantly contributes to the development of reliable switching characteristics. We have tested metal electrodes and metal oxides mostly used for memristive devices, that is, Ta, Hf, and Ti and Ta 2 O 5 , HfO 2 , and SiO 2 . Intermediate oxide layers are always formed at the interfaces, whereas only the rate of the electrode oxidation depends on the oxygen affinity of the metal and the chemical stability of the oxide matrix. Device failure is associated with complete transition of short-range order to a more disordered main matrix structure.

Synaptic behaviors of thin-film transistor with a Pt/HfO x /n-type indium-gallium-zinc oxide gate stack.

PubMed

Yang, Paul; Park, Daehoon; Beom, Keonwon; Kim, Hyung Jun; Kang, Chi Jung; Yoon, Tae-Sik

2018-07-20

We report a variety of synaptic behaviors in a thin-film transistor (TFT) with a metal-oxide-semiconductor gate stack that has a Pt/HfO x /n-type indium-gallium-zinc oxide (n-IGZO) structure. The three-terminal synaptic TFT exhibits a tunable synaptic weight with a drain current modulation upon repeated application of gate and drain voltages. The synaptic weight modulation is analog, voltage-polarity dependent reversible, and strong with a dynamic range of multiple orders of magnitude (>10 4 ). This modulation process emulates biological synaptic potentiation, depression, excitatory-postsynaptic current, paired-pulse facilitation, and short-term to long-term memory transition behaviors as a result of repeated pulsing with respect to the pulse amplitude, width, repetition number, and the interval between pulses. These synaptic behaviors are interpreted based on the changes in the capacitance of the Pt/HfO x /n-IGZO gate stack, the channel mobility, and the threshold voltage that result from the redistribution of oxygen ions by the applied gate voltage. These results demonstrate the potential of this structure for three-terminal synaptic transistor using the gate stack composed of the HfO x gate insulator and the IGZO channel layer.

Synaptic behaviors of thin-film transistor with a Pt/HfO x /n-type indium–gallium–zinc oxide gate stack

NASA Astrophysics Data System (ADS)

Yang, Paul; Park, Daehoon; Beom, Keonwon; Kim, Hyung Jun; Kang, Chi Jung; Yoon, Tae-Sik

2018-07-01

We report a variety of synaptic behaviors in a thin-film transistor (TFT) with a metal-oxide-semiconductor gate stack that has a Pt/HfO x /n-type indium–gallium–zinc oxide (n-IGZO) structure. The three-terminal synaptic TFT exhibits a tunable synaptic weight with a drain current modulation upon repeated application of gate and drain voltages. The synaptic weight modulation is analog, voltage-polarity dependent reversible, and strong with a dynamic range of multiple orders of magnitude (>104). This modulation process emulates biological synaptic potentiation, depression, excitatory-postsynaptic current, paired-pulse facilitation, and short-term to long-term memory transition behaviors as a result of repeated pulsing with respect to the pulse amplitude, width, repetition number, and the interval between pulses. These synaptic behaviors are interpreted based on the changes in the capacitance of the Pt/HfO x /n-IGZO gate stack, the channel mobility, and the threshold voltage that result from the redistribution of oxygen ions by the applied gate voltage. These results demonstrate the potential of this structure for three-terminal synaptic transistor using the gate stack composed of the HfO x gate insulator and the IGZO channel layer.

Charge transport in metal oxide nanocrystal-based materials

NASA Astrophysics Data System (ADS)

Runnerstrom, Evan Lars

There is probably no class of materials more varied, more widely used, or more ubiquitous than metal oxides. Depending on their composition, metal oxides can exhibit almost any number of properties. Of particular interest are the ways in which charge is transported in metal oxides: devices such as displays, touch screens, and smart windows rely on the ability of certain metal oxides to conduct electricity while maintaining visible transparency. Smart windows, fuel cells, and other electrochemical devices additionally rely on efficient transport of ionic charge in and around metal oxides. Colloidal synthesis has enabled metal oxide nanocrystals to emerge as a relatively new but highly tunable class of materials. Certain metal oxide nanocrystals, particularly highly doped metal oxides, have been enjoying rapid development in the last decade. As in myriad other materials systems, structure dictates the properties of metal oxide nanocrystals, but a full understanding of how nanocrystal synthesis, the processing of nanocrystal-based materials, and the structure of nanocrystals relate to the resulting properties of nanocrystal-based materials is still nascent. Gaining a fundamental understanding of and control over these structure-property relationships is crucial to developing a holistic understanding of metal oxide nanocrystals. The unique ability to tune metal oxide nanocrystals by changing composition through the introduction of dopants or by changing size and shape affords a way to study the interplay between structure, processing, and properties. This overall goal of this work is to chemically synthesize colloidal metal oxide nanocrystals, process them into useful materials, characterize charge transport in materials based on colloidal metal oxide nanocrystals, and develop ways to manipulate charge transport. In particular, this dissertation characterizes how the charge transport properties of metal oxide nanocrystal-based materials depend on their processing and

Abnormal threshold voltage shift under hot carrier stress in Ti1-xNx/HfO2 p-channel metal-oxide-semiconductor field-effect transistors

NASA Astrophysics Data System (ADS)

Tsai, Jyun-Yu; Chang, Ting-Chang; Lo, Wen-Hung; Ho, Szu-Han; Chen, Ching-En; Chen, Hua-Mao; Tseng, Tseung-Yuen; Tai, Ya-Hsiang; Cheng, Osbert; Huang, Cheng-Tung

2013-09-01

This work investigates the channel hot carrier (CHC) effect in HfO2/Ti1-xNx p-channel metal oxide semiconductor field effect transistors (p-MOSFETs). Generally, the subthreshold swing (S.S.) should increase during CHC stress (CHCS), since interface states will be generated near the drain side under high electric field due to drain voltage (Vd). However, our experimental data indicate that S.S. has no evident change under CHCS, but threshold voltage (Vth) shifts positively. This result can be attributed to hot carrier injected into high-k dielectric near the drain side. Meanwhile, it is surprising that such Vth degradation is not observed in the saturation region during stress. Therefore, drain-induced-barrier-lowering (DIBL) as a result of CHC-induced electron trapping is proposed to explain the different Vth behaviors in the linear and saturation regions. Additionally, the influence of different nitrogen concentrations in HfO2/Ti1-xNx p-MOSFETs on CHCS is also investigated in this work. Since nitrogen diffuses to SiO2/Si interface induced pre-Nit occurring to degrades channel mobility during the annealing process, a device with more nitrogen shows slightly less impact ionization, leading to insignificant charge trapping-induced DIBL behavior.

Photochemical route for accessing amorphous metal oxide materials for water oxidation catalysis.

PubMed

Smith, Rodney D L; Prévot, Mathieu S; Fagan, Randal D; Zhang, Zhipan; Sedach, Pavel A; Siu, Man Kit Jack; Trudel, Simon; Berlinguette, Curtis P

2013-04-05

Large-scale electrolysis of water for hydrogen generation requires better catalysts to lower the kinetic barriers associated with the oxygen evolution reaction (OER). Although most OER catalysts are based on crystalline mixed-metal oxides, high activities can also be achieved with amorphous phases. Methods for producing amorphous materials, however, are not typically amenable to mixed-metal compositions. We demonstrate that a low-temperature process, photochemical metal-organic deposition, can produce amorphous (mixed) metal oxide films for OER catalysis. The films contain a homogeneous distribution of metals with compositions that can be accurately controlled. The catalytic properties of amorphous iron oxide prepared with this technique are superior to those of hematite, whereas the catalytic properties of a-Fe(100-y-z)Co(y)Ni(z)O(x) are comparable to those of noble metal oxide catalysts currently used in commercial electrolyzers.

Reusable ionic liquid-catalyzed oxidative coupling of azoles and benzylic compounds via sp(3) C-N bond formation under metal-free conditions.

PubMed

Liu, Wenbo; Liu, Chenjiang; Zhang, Yonghong; Sun, Yadong; Abdukadera, Ablimit; Wang, Bin; Li, He; Ma, Xuecheng; Zhang, Zengpeng

2015-07-14

The heterocyclic ionic liquid-catalyzed direct oxidative amination of benzylic sp(3) C-H bonds via intermolecular sp(3) C-N bond formation for the synthesis of N-alkylated azoles under metal-free conditions is reported for the first time. The catalyst 1-butylpyridinium iodide can be recycled and reused with similar efficacies for at least eight cycles.

Molecular receptors in metal oxide sol-gel materials prepared via molecular imprinting

DOEpatents

Sasaki, Darryl Y.; Brinker, C. Jeffrey; Ashley, Carol S.; Daitch, Charles E.; Shea, Kenneth J.; Rush, Daniel J.

2000-01-01

A method is provided for molecularly imprinting the surface of a sol-gel material, by forming a solution comprised of a sol-gel material, a solvent, an imprinting molecule, and a functionalizing siloxane monomer of the form Si(OR).sub.3-n X.sub.n, wherein n is an integer between zero and three and X is a functional group capable of reacting with the imprinting molecule, evaporating the solvent, and removing the imprinting molecule to form the molecularly imprinted metal oxide sol-gel material. The use of metal oxide sol-gels allows the material porosity, pore size, density, surface area, hardness, electrostatic charge, polarity, optical density, and surface hydrophobicity to be tailored and be employed as sensors and in catalytic and separations operations.

Synthesis of Oxides Containing Transition Metals

DTIC Science & Technology

1990-07-09

metal oxide single crystals by the electrolysis of molten salts containing mixtures of the appropriate oxides. Andreiux and Bozon (33-34) were able to...examples of unusual transition metal oxides which can be prepared (usually as single crystals) by electrolysis of fused salts . Summary The methods of...ferrites with the composition MFe 204 involved the thermal decomposition of oxalate (3) or pyridinate salts (1). The synthesis of ferrites from mixed

Trace Metal Requirements for Microbial Enzymes Involved in the Production and Consumption of Methane and Nitrous Oxide

PubMed Central

Glass, Jennifer B.; Orphan, Victoria J.

2011-01-01

Fluxes of greenhouse gases to the atmosphere are heavily influenced by microbiological activity. Microbial enzymes involved in the production and consumption of greenhouse gases often contain metal cofactors. While extensive research has examined the influence of Fe bioavailability on microbial CO2 cycling, fewer studies have explored metal requirements for microbial production and consumption of the second- and third-most abundant greenhouse gases, methane (CH4), and nitrous oxide (N2O). Here we review the current state of biochemical, physiological, and environmental research on transition metal requirements for microbial CH4 and N2O cycling. Methanogenic archaea require large amounts of Fe, Ni, and Co (and some Mo/W and Zn). Low bioavailability of Fe, Ni, and Co limits methanogenesis in pure and mixed cultures and environmental studies. Anaerobic methane oxidation by anaerobic methanotrophic archaea (ANME) likely occurs via reverse methanogenesis since ANME possess most of the enzymes in the methanogenic pathway. Aerobic CH4 oxidation uses Cu or Fe for the first step depending on Cu availability, and additional Fe, Cu, and Mo for later steps. N2O production via classical anaerobic denitrification is primarily Fe-based, whereas aerobic pathways (nitrifier denitrification and archaeal ammonia oxidation) require Cu in addition to, or possibly in place of, Fe. Genes encoding the Cu-containing N2O reductase, the only known enzyme capable of microbial N2O conversion to N2, have only been found in classical denitrifiers. Accumulation of N2O due to low Cu has been observed in pure cultures and a lake ecosystem, but not in marine systems. Future research is needed on metalloenzymes involved in the production of N2O by enrichment cultures of ammonia oxidizing archaea, biological mechanisms for scavenging scarce metals, and possible links between metal bioavailability and greenhouse gas fluxes in anaerobic environments where metals may be limiting due to sulfide-metal

Planar ceramic membrane assembly and oxidation reactor system

DOEpatents

Carolan, Michael Francis; Dyer, legal representative, Kathryn Beverly; Wilson, Merrill Anderson; Ohm, Ted R.; Kneidel, Kurt E.; Peterson, David; Chen, Christopher M.; Rackers, Keith Gerard; Dyer, deceased, Paul Nigel

2007-10-09

Planar ceramic membrane assembly comprising a dense layer of mixed-conducting multi-component metal oxide material, wherein the dense layer has a first side and a second side, a porous layer of mixed-conducting multi-component metal oxide material in contact with the first side of the dense layer, and a ceramic channeled support layer in contact with the second side of the dense layer. The planar ceramic membrane assembly can be used in a ceramic wafer assembly comprising a planar ceramic channeled support layer having a first side and a second side; a first dense layer of mixed-conducting multi-component metal oxide material having an inner side and an outer side, wherein the inner side is in contact with the first side of the ceramic channeled support layer; a first outer support layer comprising porous mixed-conducting multi-component metal oxide material and having an inner side and an outer side, wherein the inner side is in contact with the outer side of the first dense layer; a second dense layer of mixed-conducting multi-component metal oxide material having an inner side and an outer side, wherein the inner side is in contact with the second side of the ceramic channeled layer; and a second outer support layer comprising porous mixed-conducting multi-component metal oxide material and having an inner side and an outer side, wherein the inner side is in contact with the outer side of the second dense layer.

Planar ceramic membrane assembly and oxidation reactor system

DOEpatents

Carolan, Michael Francis; Dyer, legal representative, Kathryn Beverly; Wilson, Merrill Anderson; Ohrn, Ted R.; Kneidel, Kurt E.; Peterson, David; Chen, Christopher M.; Rackers, Keith Gerard; Dyer, Paul Nigel

2009-04-07

Planar ceramic membrane assembly comprising a dense layer of mixed-conducting multi-component metal oxide material, wherein the dense layer has a first side and a second side, a porous layer of mixed-conducting multi-component metal oxide material in contact with the first side of the dense layer, and a ceramic channeled support layer in contact with the second side of the dense layer. The planar ceramic membrane assembly can be used in a ceramic wafer assembly comprising a planar ceramic channeled support layer having a first side and a second side; a first dense layer of mixed-conducting multi-component metal oxide material having an inner side and an outer side, wherein the inner side is in contact with the first side of the ceramic channeled support layer; a first outer support layer comprising porous mixed-conducting multi-component metal oxide material and having an inner side and an outer side, wherein the inner side is in contact with the outer side of the first dense layer; a second dense layer of mixed-conducting multi-component metal oxide material having an inner side and an outer side, wherein the inner side is in contact with the second side of the ceramic channeled layer; and a second outer support layer comprising porous mixed-conducting multi-component metal oxide material and having an inner side and an outer side, wherein the inner side is in contact with the outer side of the second dense layer.

Recent Advances of Solution-Processed Metal Oxide Thin-Film Transistors.

PubMed

Xu, Wangying; Li, Hao; Xu, Jian-Bin; Wang, Lei

2018-03-06

Solution-processed metal oxide thin-film transistors (TFTs) are considered as one of the most promising transistor technologies for future large-area flexible electronics. This review surveys the recent advances in solution-based oxide TFTs, including n-type oxide semiconductors, oxide dielectrics and p-type oxide semiconductors. Firstly, we provide an introduction on oxide TFTs and the TFT configurations and operating principles. Secondly, we present the recent progress in solution-processed n-type transistors, with a special focus on low-temperature and large-area solution processed approaches as well as novel non-display applications. Thirdly, we give a detailed analysis of the state-of-the-art solution-processed oxide dielectrics for low-voltage electronics. Fourthly, we discuss the recent progress in solution-based p-type oxide semiconductors, which will enable the highly desirable future low-cost large-area complementary circuits. Finally, we draw the conclusions and outline the perspectives over the research field.

40 CFR 721.4610 - Mixed metal oxides (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Mixed metal oxides (generic). 721.4610... Substances § 721.4610 Mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxides (PMN P-98-0002...

40 CFR 721.10006 - Mixed metal oxide (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Mixed metal oxide (generic). 721.10006... Substances § 721.10006 Mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxide (PMN P-99-511...

40 CFR 721.4610 - Mixed metal oxides (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Mixed metal oxides (generic). 721.4610... Substances § 721.4610 Mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxides (PMN P-98-0002...

40 CFR 721.10006 - Mixed metal oxide (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Mixed metal oxide (generic). 721.10006... Substances § 721.10006 Mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxide (PMN P-99-511...

40 CFR 721.4610 - Mixed metal oxides (generic).

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Mixed metal oxides (generic). 721.4610... Substances § 721.4610 Mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxides (PMN P-98-0002...

40 CFR 721.4610 - Mixed metal oxides (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Mixed metal oxides (generic). 721.4610... Substances § 721.4610 Mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxides (PMN P-98-0002...

40 CFR 721.10006 - Mixed metal oxide (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Mixed metal oxide (generic). 721.10006... Substances § 721.10006 Mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxide (PMN P-99-511...

40 CFR 721.4610 - Mixed metal oxides (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Mixed metal oxides (generic). 721.4610... Substances § 721.4610 Mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxides (PMN P-98-0002...

40 CFR 721.10006 - Mixed metal oxide (generic).

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Mixed metal oxide (generic). 721.10006... Substances § 721.10006 Mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as mixed metal oxide (PMN P-99-511...

40 CFR 721.5548 - Mixed metal oxide (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Mixed metal oxide (generic). 721.5548... Substances § 721.5548 Mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a mixed metal oxide (PMN P-97-956) is...

40 CFR 721.5548 - Mixed metal oxide (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Mixed metal oxide (generic). 721.5548... Substances § 721.5548 Mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a mixed metal oxide (PMN P-97-956) is...

40 CFR 721.5548 - Mixed metal oxide (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Mixed metal oxide (generic). 721.5548... Substances § 721.5548 Mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a mixed metal oxide (PMN P-97-956) is...

40 CFR 721.5548 - Mixed metal oxide (generic).

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Mixed metal oxide (generic). 721.5548... Substances § 721.5548 Mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a mixed metal oxide (PMN P-97-956) is...

40 CFR 721.5548 - Mixed metal oxide (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Mixed metal oxide (generic). 721.5548... Substances § 721.5548 Mixed metal oxide (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a mixed metal oxide (PMN P-97-956) is...

Ammonia release method for depositing metal oxides

DOEpatents

Silver, Gary L.; Martin, Frank S.

1994-12-13

A method of depositing metal oxides on substrates which is indifferent to the electrochemical properties of the substrates and which comprises forming ammine complexes containing metal ions and thereafter effecting removal of ammonia from the ammine complexes so as to permit slow precipitation and deposition of metal oxide on the substrates.

Dextran templating for the synthesis of metallic and metal oxide sponges

NASA Astrophysics Data System (ADS)

Walsh, Dominic; Arcelli, Laura; Ikoma, Toshiyuki; Tanaka, Junzo; Mann, Stephen

2003-06-01

Silver or gold-containing porous frameworks have been used extensively in catalysis, electrochemistry, heat dissipation and biofiltration. These materials are often prepared by thermal reduction of metal-ion-impregnated porous insoluble supports (such as alumina and pumice), and have surface areas of about 1 m2 g-1, which is typically higher than that obtained for pure metal powders or foils prepared electrolytically or by infiltration and thermal decomposition of insoluble cellulose supports. Starch gels have been used in association with zeolite nanoparticles to produce porous inorganic materials with structural hierarchy, but the use of soft sacrificial templates in the synthesis of metallic sponges has not been investigated. Here we demonstrate that self-supporting macroporous frameworks of silver, gold and copper oxide, as well as composites of silver/copper oxide or silver/titania can be routinely prepared by heating metal-salt-containing pastes of the polysaccharide, dextran, to temperatures between 500 and 900 °C. Magnetic sponges were similarly prepared by replacing the metal salt precursor with preformed iron oxide (magnetite) nanoparticles. The use of dextran as a sacrificial template for the fabrication of metallic and metal oxide sponges should have significant benefits over existing technologies because the method is facile, inexpensive, environmentally benign, and amenable to scale-up and processing.

Conduction Channel Formation and Dissolution Due to Oxygen Thermophoresis/Diffusion in Hafnium Oxide Memristors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Suhas; Wang, Ziwen; Huang, Xiaopeng

Due to the favorable operating power, endurance, speed, and density., transition-metal-oxide memristors, or resistive random-access memory (RRAM) switches, are under intense development for storage-class memory. Their commercial deployment critically depends on predictive compact models based on understanding nanoscale physiocochemical forces, which remains elusive and controversial owing to the difficulties in directly observing atomic motions during resistive switching, Here, using scanning transmission synchrotron X-ray spectromicroscopy to study in situ switching of hafnium oxide memristors, we directly observed the formation of a localized oxygen-deficiency-derived conductive channel surrounded by a low-conductivity ring of excess oxygen. Subsequent thermal annealing homogenized the segregated oxygen, resettingmore » the cells toward their as-grown resistance state. We show that the formation and dissolution of the conduction channel are successfully modeled by radial thermophoresis and Fick diffusion of oxygen atoms driven by Joule heating. This confirmation and quantification of two opposing nanoscale radial forces that affect bipolar memristor switching are important components for any future physics-based compact model for the electronic switching of these devices.« less

AlN metal-semiconductor field-effect transistors using Si-ion implantation

NASA Astrophysics Data System (ADS)

Okumura, Hironori; Suihkonen, Sami; Lemettinen, Jori; Uedono, Akira; Zhang, Yuhao; Piedra, Daniel; Palacios, Tomás

2018-04-01

We report on the electrical characterization of Si-ion implanted AlN layers and the first demonstration of metal-semiconductor field-effect transistors (MESFETs) with an ion-implanted AlN channel. The ion-implanted AlN layers with Si dose of 5 × 1014 cm-2 exhibit n-type characteristics after thermal annealing at 1230 °C. The ion-implanted AlN MESFETs provide good drain current saturation and stable pinch-off operation even at 250 °C. The off-state breakdown voltage is 2370 V for drain-to-gate spacing of 25 µm. These results show the great potential of AlN-channel transistors for high-temperature and high-power applications.

Direct electrochemical reduction of metal-oxides

DOEpatents

Redey, Laszlo I.; Gourishankar, Karthick

2003-01-01

A method of controlling the direct electrolytic reduction of a metal oxide or mixtures of metal oxides to the corresponding metal or metals. A non-consumable anode and a cathode and a salt electrolyte with a first reference electrode near the non-consumable anode and a second reference electrode near the cathode are used. Oxygen gas is produced and removed from the cell. The anode potential is compared to the first reference electrode to prevent anode dissolution and gas evolution other than oxygen, and the cathode potential is compared to the second reference electrode to prevent production of reductant metal from ions in the electrolyte.

CO-oxidation catalysts: Low-temperature CO oxidation over Noble-Metal Reducible Oxide (NMRO) catalysts

NASA Technical Reports Server (NTRS)

Herz, Richard K.

1990-01-01

Oxidation of CO to CO2 is an important reaction technologically and environmentally and a complex and interesting reaction scientifically. In most cases, the reaction is carried out in order to remove CO as an environmental hazard. A major application of heterogeneous catalysts is catalytic oxidation of CO in the exhaust of combustion devices. The reaction over catalysts in exhaust gas is fast and often mass-transfer-limited since exhaust gases are hot and O2/CO ratios are high. The main challenges to catalyst designers are to control thermal sintering and chemical poisoning of the active materials. The effect of the noble metal on the oxide is discussed, followed by the effect of the oxide on the noble metal, the interaction of the noble metal and oxide to form unique catalytic sites, and the possible ways in which the CO oxidation reaction is catalyzed by the NMRO materials.

Synthesis and applications of nanoporous perovskite metal oxides

PubMed Central

Huang, Xiubing; Zhao, Guixia

2018-01-01

Perovskite-type metal oxides have been widely investigated and applied in various fields in the past several decades due to their extraordinary variability of compositions and structures with targeted physical and chemical properties (e.g., redox behaviour, oxygen mobility, electronic and ionic conductivity). Recently, nanoporous perovskite metal oxides have attracted extensive attention because of their special morphology and properties, as well as superior performance. This minireview aims at summarizing and reviewing the different synthesis methods of nanoporous perovskite metal oxides and their various applications comprehensively. The correlations between the nanoporous structures and the specific performance of perovskite oxides are summarized and highlighted. The future research directions of nanoporous perovskite metal oxides are also prospected. PMID:29862001

Ammonia release method for depositing metal oxides

DOEpatents

Silver, G.L.; Martin, F.S.

1994-12-13

A method is described for depositing metal oxides on substrates which is indifferent to the electrochemical properties of the substrates and which comprises forming ammine complexes containing metal ions and thereafter effecting removal of ammonia from the ammine complexes so as to permit slow precipitation and deposition of metal oxide on the substrates. 1 figure.

X-ray Absorption Study of Graphene Oxide and Transition Metal Oxide Nanocomposites.

PubMed

Gandhiraman, Ram P; Nordlund, Dennis; Javier, Cristina; Koehne, Jessica E; Chen, Bin; Meyyappan, M

2014-08-14

The surface properties of the electrode materials play a crucial role in determining the performance and efficiency of energy storage devices. Graphene oxide and nanostructures of 3d transition metal oxides were synthesized for construction of electrodes in supercapacitors, and the electronic structure and oxidation states were probed using near-edge X-ray absorption fine structure. Understanding the chemistry of graphene oxide would provide valuable insight into its reactivity and properties as the graphene oxide transformation to reduced-graphene oxide is a key step in the synthesis of the electrode materials. Polarized behavior of the synchrotron X-rays and the angular dependency of the near-edge X-ray absorption fine structures (NEXAFS) have been utilized to study the orientation of the σ and π bonds of the graphene oxide and graphene oxide-metal oxide nanocomposites. The core-level transitions of individual metal oxides and that of the graphene oxide nanocomposite showed that the interaction of graphene oxide with the metal oxide nanostructures has not altered the electronic structure of either of them. As the restoration of the π network is important for good electrical conductivity, the C K edge NEXAFS spectra of reduced graphene oxide nanocomposites confirms the same through increased intensity of the sp 2 -derived unoccupied states π* band. A pronounced angular dependency of the reduced sample and the formation of excitonic peaks confirmed the formation of extended conjugated network.

Ultrathin body GaSb-on-insulator p-channel metal-oxide-semiconductor field-effect transistors on Si fabricated by direct wafer bonding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yokoyama, Masafumi, E-mail: yokoyama@mosfet.t.u-tokyo.ac.jp; Takenaka, Mitsuru; Takagi, Shinichi

2015-02-16

We have realized ultrathin body GaSb-on-insulator (GaSb-OI) on Si wafers by direct wafer bonding technology using atomic-layer deposition (ALD) Al{sub 2}O{sub 3} and have demonstrated GaSb-OI p-channel metal-oxide-semiconductor field-effect transistors (p-MOSFETs) on Si. A 23-nm-thick GaSb-OI p-MOSFET exhibits the peak effective mobility of ∼76 cm{sup 2}/V s. We have found that the effective hole mobility of the thin-body GaSb-OI p-MOSFETs decreases with a decrease in the GaSb-OI thickness or with an increase in Al{sub 2}O{sub 3} ALD temperature. The InAs passivation of GaSb-OI MOS interfaces can enhance the peak effective mobility up to 159 cm{sup 2}/V s for GaSb-OI p-MOSFETs with themore » 20-nm-thick GaSb layer.« less

Ionic Liquid Activation of Amorphous Metal-Oxide Semiconductors for Flexible Transparent Electronic Devices

DOE PAGES

Pudasaini, Pushpa Raj; Noh, Joo Hyon; Wong, Anthony T.; ...

2016-02-09

To begin this abstract, amorphous metal-oxide semiconductors offer the high carrier mobilities and excellent large-area uniformity required for high performance, transparent, flexible electronic devices; however, a critical bottleneck to their widespread implementation is the need to activate these materials at high temperatures which are not compatible with flexible polymer substrates. The highly controllable activation of amorphous indium gallium zinc oxide semiconductor channels using ionic liquid gating at room temperature is reported. Activation is controlled by electric field-induced oxygen migration across the ionic liquid-semiconductor interface. In addition to activation of unannealed devices, it is shown that threshold voltages of a transistormore » can be linearly tuned between the enhancement and depletion modes. Finally, the first ever example of transparent flexible thin film metal oxide transistor on a polyamide substrate created using this simple technique is demonstrated. Finally, this study demonstrates the potential of field-induced activation as a promising alternative to traditional postdeposition thermal annealing which opens the door to wide scale implementation into flexible electronic applications.« less

Acoustic wave-driven oxidized liquid metal-based energy harvester

NASA Astrophysics Data System (ADS)

Jeon, Jinpyo; Chung, Sang Kug; Lee, Jeong-Bong; Doo, Seok Joo; Kim, Daeyoung

2018-06-01

We report an oxidized liquid metal droplet-based energy harvester that converts acoustic energy into electrical energy by modulating an electrical double layer that originates from the deformation of the oxidized liquid metal droplet. Gallium-based liquid metal alloy has been developed for various applications owing to the outstanding material properties, such as its high electrical conductivity (metallic property) and unlimited deformability (liquid property). In this study, we demonstrated energy harvesting using an electrical double layer between the acoustic wave-modulated liquid metal droplet and two electrodes. The proposed energy harvester consisted of top and bottom electrodes covered with the dielectric layer and a Gallium-based liquid metal droplet placed between the electrodes. When we applied an external bias voltage and acoustic wave to the proposed device, the contact area between the liquid metal droplet and the electrodes changed, leading to the variation of the capacitance in the electrical double layer and the generation of electrical output current. Using the proposed energy harvester, the maximum output current of 41.2 nA was generated with an applied acoustic wave of 30 Hz. In addition, we studied the relationships between the maximum output current and a variety of factors, such as the size of the liquid metal droplet, the thickness of the hydrophobic layer, and the distance between the top and bottom electrode plates.

Metal/oxide interfacial effects on the selective oxidation of primary alcohols

PubMed Central

Zhao, Guofeng; Yang, Fan; Chen, Zongjia; Liu, Qingfei; Ji, Yongjun; Zhang, Yi; Niu, Zhiqiang; Mao, Junjie; Bao, Xinhe; Hu, Peijun; Li, Yadong

2017-01-01

A main obstacle in the rational development of heterogeneous catalysts is the difficulty in identifying active sites. Here we show metal/oxide interfacial sites are highly active for the oxidation of benzyl alcohol and other industrially important primary alcohols on a range of metals and oxides combinations. Scanning tunnelling microscopy together with density functional theory calculations on FeO/Pt(111) reveals that benzyl alcohol enriches preferentially at the oxygen-terminated FeO/Pt(111) interface and undergoes readily O–H and C–H dissociations with the aid of interfacial oxygen, which is also validated in the model study of Cu2O/Ag(111). We demonstrate that the interfacial effects are independent of metal or oxide sizes and the way by which the interfaces were constructed. It inspires us to inversely support nano-oxides on micro-metals to make the structure more stable against sintering while the number of active sites is not sacrificed. The catalyst lifetime, by taking the inverse design, is thereby significantly prolonged. PMID:28098146

Covalent bonding in heavy metal oxides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bagus, Paul S.; Nelin, Connie J.; Hrovat, Dave A.

Novel theoretical methods were used to quantify the magnitude and the energetic contributions of 4f/5f-O2p and 5d/6d-O2p interactions to covalent bonding in lanthanide and actinide oxides. Although many analyses have neglected the involvement of the frontier d orbitals, the present study shows that f and d covalency are of comparable importance. Two trends are identified. As is expected, the covalent mixing is larger when the nominal oxidation state is higher. More subtly, the importance of the nf covalent mixing decreases sharply relative to (n+1)d as the nf occupation increases. Atomic properties of the metal cations that drive these trends aremore » identified.« less

Metal oxide composite enabled nanotextured Si photoanode for efficient solar driven water oxidation.

PubMed

Sun, Ke; Pang, Xiaolu; Shen, Shaohua; Qian, Xueqiang; Cheung, Justin S; Wang, Deli

2013-05-08

We present a study of a transition metal oxide composite modified n-Si photoanode for efficient and stable water oxidation. This sputter-coated composite functions as a protective coating to prevent Si from photodecomposition, a Schottky heterojunction, a hole conducting layer for efficient charge separation and transportation, and an electrocatalyst to reduce the reaction overpotential. The formation of mixed-valence oxides composed of Ni and Ru effectively modifies the optical, electrical, and catalytic properties of the coating material, as well as the interfaces with Si. The successful application of this oxide composite on nanotextured Si demonstrates improved conversion efficiency due to enhanced catalytic activity, minimized reflection, and increased surface reaction sites. Although the coated nanotextured Si shows a noticeable degradation from 500 cycles of operation, the oxide composite provides a simple method to enable unstable photoanode materials for solar fuel conversion.

Synergistic approach to high-performance oxide thin film transistors using a bilayer channel architecture.

PubMed

Yu, Xinge; Zhou, Nanjia; Smith, Jeremy; Lin, Hui; Stallings, Katie; Yu, Junsheng; Marks, Tobin J; Facchetti, Antonio

2013-08-28

We report here a bilayer metal oxide thin film transistor concept (bMO TFT) where the channel has the structure: dielectric/semiconducting indium oxide (In2O3) layer/semiconducting indium gallium oxide (IGO) layer. Both semiconducting layers are grown from solution via a low-temperature combustion process. The TFT mobilities of bottom-gate/top-contact bMO TFTs processed at T = 250 °C are ~5tmex larger (~2.6 cm(2)/(V s)) than those of single-layer IGO TFTs (~0.5 cm(2)/(V s)), reaching values comparable to single-layer combustion-processed In2O3 TFTs (~3.2 cm(2)/(V s)). More importantly, and unlike single-layer In2O3 TFTs, the threshold voltage of the bMO TFTs is ~0.0 V, and the current on/off ratio is significantly enhanced to ~1 × 10(8) (vs ~1 × 10(4) for In2O3). The microstructure and morphology of the In2O3/IGO bilayers are analyzed by X-ray diffraction, atomic force microscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy, revealing the polycrystalline nature of the In2O3 layer and the amorphous nature of the IGO layer. This work demonstrates that solution-processed metal oxides can be implemented in bilayer TFT architectures with significantly enhanced performance.

Three-electrode metal oxide reduction cell

DOEpatents

Dees, Dennis W.; Ackerman, John P.

2008-08-12

A method of electrochemically reducing a metal oxide to the metal in an electrochemical cell is disclosed along with the cell. Each of the anode and cathode operate at their respective maximum reaction rates. An electrolyte and an anode at which oxygen can be evolved, and a cathode including a metal oxide to be reduced are included as is a third electrode with independent power supplies connecting the anode and the third electrode and the cathode and the third electrode.

Three-Electrode Metal Oxide Reduction Cell

DOEpatents

Dees, Dennis W.; Ackerman, John P.

2005-06-28

A method of electrochemically reducing a metal oxide to the metal in an electrochemical cell is disclosed along with the cell. Each of the anode and cathode operate at their respective maximum reaction rates. An electrolyte and an anode at which oxygen can be evolved, and a cathode including a metal oxide to be reduced are included as is a third electrode with independent power supplies connecting the anode and the third electrode and the cathode and the third electrode.

Monolithic integration of GaN-based light-emitting diodes and metal-oxide-semiconductor field-effect transistors.

PubMed

Lee, Ya-Ju; Yang, Zu-Po; Chen, Pin-Guang; Hsieh, Yung-An; Yao, Yung-Chi; Liao, Ming-Han; Lee, Min-Hung; Wang, Mei-Tan; Hwang, Jung-Min

2014-10-20

In this study, we report a novel monolithically integrated GaN-based light-emitting diode (LED) with metal-oxide-semiconductor field-effect transistor (MOSFET). Without additionally introducing complicated epitaxial structures for transistors, the MOSFET is directly fabricated on the exposed n-type GaN layer of the LED after dry etching, and serially connected to the LED through standard semiconductor-manufacturing technologies. Such monolithically integrated LED/MOSFET device is able to circumvent undesirable issues that might be faced by other kinds of integration schemes by growing a transistor on an LED or vice versa. For the performances of resulting device, our monolithically integrated LED/MOSFET device exhibits good characteristics in the modulation of gate voltage and good capability of driving injected current, which are essential for the important applications such as smart lighting, interconnection, and optical communication.

PCDD/F catalysis by metal chlorides and oxides.

PubMed

Zhang, Mengmei; Yang, Jie; Buekens, Alfons; Olie, Kees; Li, Xiaodong

2016-09-01

Model fly ash (MFA) samples were composed of silica, sodium chloride, and activated carbon, and doped with metal (0.1 wt% Cu, Cr, Ni, Zn and Cd) chloride or oxide. Each sample was de novo tested at 350 °C for 1 h, in a flow of gas (N2, N2 + 10% O2, +21% O2 or +10% H2) to investigate the effect of metal catalyst and gas composition on PCDD/F formation. Total PCDD/F yield rises rapidly with oxygen content, while the addition of hydrogen inhibits the formation and chlorination of PCDD/F. The amount of PCDD on average rises linearly with the oxygen concentration, while that of PCDF follows a reaction order of about 1/2; thus the PCDF to PCDD ratio drops when more oxygen becomes available. Some samples do not follow this trend. Chlorides are much more active than oxides, yet there are marked differences between individual metals. Principal component analysis (PCA) was applied to study the signatures from all samples, showing their unique specificity and diversity. Each catalyst shows a different signature within its individual homologue groups, demonstrating that these signatures are not thermodynamically controlled. Average congener patterns do not vary considerably with oxygen content changing from oxidising (air) to reducing (nitrogen, hydrogen). Copyright © 2016 Elsevier Ltd. All rights reserved.

Metal Oxide Supported Vanadium Substituted Keggin Type Polyoxometalates as Catalyst For Oxidation of Dibenzothiophene

NASA Astrophysics Data System (ADS)

Lesbani, Aldes; Novri Meilyana, Sarah; Karim, Nofi; Hidayati, Nurlisa; Said, Muhammad; Mohadi, Risfidian; Miksusanti

2018-01-01

Supported polyoxometalatate H4[γ-H2SiV2W10O40]·nH2O with metal oxide i.e. silica, titanium, and tantalum was successfully synthesized via wet impregnation method to form H4[γ-H2SiV2W10O40]·nH2O-Si, H4[γ-H2SiV2W10O40]·nH2O-Ti, and H4[γ-H2SiV2W10O40]·nH2O-Ta. Characterization was performed using FTIR spectroscopy, X-Ray analyses, and morphology analyses using SEM. All compounds were used as the catalyst for desulfurization of dibenzothiophene (DBT). Silica and titanium supported polyoxometalate H4[γ-H2SiV2W10O40]·nH2O better than tantalum due to retaining crystallinity after impregnation process. On the other hand, compound H H4[γ-H2SiV2W10O40]·nH2O-Ta showed high catalytic activity than other supported metal oxides for desulfurization of DBT. Optimization desulfurization process resulted in 99% conversion of DBT under a mild condition at 70 °C, 0.1 g catalyst, and reaction for 3 hours. Regeneration studies showed catalyst H4[γ-H2SiV2W10O40]·nH2O-Ti was remaining catalytic activity for desulfurization of DBT.

Ketones Prevent Oxidative Impairment of Hippocampal Synaptic Integrity through KATP Channels

PubMed Central

Kim, Do Young; Abdelwahab, Mohammed G.; Lee, Soo Han; O’Neill, Derek; Thompson, Roger J.; Duff, Henry J.; Sullivan, Patrick G.; Rho, Jong M.

2015-01-01

Dietary and metabolic therapies are increasingly being considered for a variety of neurological disorders, based in part on growing evidence for the neuroprotective properties of the ketogenic diet (KD) and ketones. Earlier, we demonstrated that ketones afford hippocampal synaptic protection against exogenous oxidative stress, but the mechanisms underlying these actions remain unclear. Recent studies have shown that ketones may modulate neuronal firing through interactions with ATP-sensitive potassium (KATP) channels. Here, we used a combination of electrophysiological, pharmacological, and biochemical assays to determine whether hippocampal synaptic protection by ketones is a consequence of KATP channel activation. Ketones dose-dependently reversed oxidative impairment of hippocampal synaptic integrity, neuronal viability, and bioenergetic capacity, and this action was mirrored by the KATP channel activator diazoxide. Inhibition of KATP channels reversed ketone-evoked hippocampal protection, and genetic ablation of the inwardly rectifying K+ channel subunit Kir6.2, a critical component of KATP channels, partially negated the synaptic protection afforded by ketones. This partial protection was completely reversed by co-application of the KATP blocker, 5-hydoxydecanoate (5HD). We conclude that, under conditions of oxidative injury, ketones induce synaptic protection in part through activation of KATP channels. PMID:25848768

Near interface traps in SiO{sub 2}/4H-SiC metal-oxide-semiconductor field effect transistors monitored by temperature dependent gate current transient measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fiorenza, Patrick; La Magna, Antonino; Vivona, Marilena

This letter reports on the impact of gate oxide trapping states on the conduction mechanisms in SiO{sub 2}/4H-SiC metal-oxide-semiconductor field effect transistors (MOSFETs). The phenomena were studied by gate current transient measurements, performed on n-channel MOSFETs operated in “gate-controlled-diode” configuration. The measurements revealed an anomalous non-steady conduction under negative bias (V{sub G} > |20 V|) through the SiO{sub 2}/4H-SiC interface. The phenomenon was explained by the coexistence of a electron variable range hopping and a hole Fowler-Nordheim (FN) tunnelling. A semi-empirical modified FN model with a time-depended electric field is used to estimate the near interface traps in the gate oxide (N{sub trap} ∼ 2 × 10{supmore » 11} cm{sup −2}).« less

Epitaxial ZnO gate dielectrics deposited by RF sputter for AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors

NASA Astrophysics Data System (ADS)

Yoon, Seonno; Lee, Seungmin; Kim, Hyun-Seop; Cha, Ho-Young; Lee, Hi-Deok; Oh, Jungwoo

2018-01-01

Radio frequency (RF)-sputtered ZnO gate dielectrics for AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs) were investigated with varying O2/Ar ratios. The ZnO deposited with a low oxygen content of 4.5% showed a high dielectric constant and low interface trap density due to the compensation of oxygen vacancies during the sputtering process. The good capacitance-voltage characteristics of ZnO-on-AlGaN/GaN capacitors resulted from the high crystallinity of oxide at the interface, as investigated by x-ray diffraction and high-resolution transmission electron microscopy. The MOS-HEMTs demonstrated comparable output electrical characteristics with conventional Ni/Au HEMTs but a lower gate leakage current. At a gate voltage of -20 V, the typical gate leakage current for a MOS-HEMT with a gate length of 6 μm and width of 100 μm was found to be as low as 8.2 × 10-7 mA mm-1, which was three orders lower than that of the Ni/Au Schottky gate HEMT. The reduction of the gate leakage current improved the on/off current ratio by three orders of magnitude. These results indicate that RF-sputtered ZnO with a low O2/Ar ratio is a good gate dielectric for high-performance AlGaN/GaN MOS-HEMTs.

Oxide surfaces and metal/oxide interfaces studied by grazing incidence X-ray scattering

NASA Astrophysics Data System (ADS)

Renaud, Gilles

Experimental determinations of the atomic structure of insulating oxide surfaces and metal/oxide interfaces are scarce, because surface science techniques are often limited by the insulating character of the substrate. Grazing incidence X-ray scattering (GIXS), which is not subject to charge effects, can provide very precise information on the atomic structure of oxide surfaces: roughness, relaxation and reconstruction. It is also well adapted to analyze the atomic structure, the registry, the misfit relaxation, elastic or plastic, the growth mode and the morphology of metal/oxide interfaces during their growth, performed in situ. GIXS also allows the analysis of thin films and buried interfaces, in a non-destructive way, yielding the epitaxial relationships, and, by variation of the grazing incidence angle, the lattice parameter relaxation along the growth direction. On semi-coherent interfaces, the existence of an ordered network of interfacial misfit dislocations can be demonstrated, its Burger's vector determined, its ordering during in situ annealing cycles followed, and sometimes even its atomic structure can be addressed. Careful analysis during growth allows the modeling of the dislocation nucleation process. This review emphasizes the new information that GIXS can bring to oxide surfaces and metal/oxide interfaces by comparison with other surface science techniques. The principles of X-ray diffraction by surfaces and interfaces are recalled, together with the advantages and properties of grazing angles. The specific experimental requirements are discussed. Recent results are presented on the determination of the atomic structure of relaxed or reconstructed oxide surfaces. A description of results obtained during the in situ growth of metal on oxide surfaces is also given, as well as investigations of thick metal films on oxide surfaces, with lattice parameter misfit relaxed by an array of dislocations. Recent work performed on oxide thin films having

Lithium metal oxide electrodes for lithium batteries

DOEpatents

Thackeray, Michael M [Naperville, IL; Kim, Jeom-Soo [Naperville, IL; Johnson, Christopher S [Naperville, IL

2008-01-01

An uncycled electrode for a non-aqueous lithium electrochemical cell including a lithium metal oxide having the formula Li.sub.(2+2x)/(2+x)M'.sub.2x/(2+x)M.sub.(2-2x)/(2+x)O.sub.2-.delta., in which 0.ltoreq.x<1 and .delta. is less than 0.2, and in which M is a non-lithium metal ion with an average trivalent oxidation state selected from two or more of the first row transition metals or lighter metal elements in the periodic table, and M' is one or more ions with an average tetravalent oxidation state selected from the first and second row transition metal elements and Sn. Methods of preconditioning the electrodes are disclosed as are electrochemical cells and batteries containing the electrodes.

Metal-oxide-based energetic materials and synthesis thereof

DOEpatents

Tillotson, Thomas M. , Simpson; Randall, L [Livermore, CA; Hrubesh, Lawrence W [Pleasanton, CA

2006-01-17

A method of preparing energetic metal-oxide-based energetic materials using sol-gel chemistry has been invented. The wet chemical sol-gel processing provides an improvement in both safety and performance. Essentially, a metal-oxide oxidizer skeletal structure is prepared from hydrolyzable metals (metal salts or metal alkoxides) with fuel added to the sol prior to gelation or synthesized within the porosity metal-oxide gel matrix. With metal salt precursors a proton scavenger is used to destabilize the sol and induce gelation. With metal alkoxide precursors standard well-known sol-gel hydrolysis and condensation reactions are used. Drying is done by standard sol-gel practices, either by a slow evaporation of the liquid residing within the pores to produce a high density solid nanocomposite, or by supercritical extraction to produce a lower density, high porous nanocomposite. Other ingredients may be added to this basic nanostructure to change physical and chemical properties, which include organic constituents for binders or gas generators during reactions, burn rate modifiers, or spectral emitters.

Remarkably high mobility ultra-thin-film metal-oxide transistor with strongly overlapped orbitals

NASA Astrophysics Data System (ADS)

Wei Shih, Chen; Chin, Albert; Fu Lu, Chun; Fang Su, Wei

2016-01-01

High mobility channel thin-film-transistor (TFT) is crucial for both display and future generation integrated circuit. We report a new metal-oxide TFT that has an ultra-thin 4.5 nm SnO2 thickness for both active channel and source-drain regions, very high 147 cm2/Vs field-effect mobility, high ION/IOFF of 2.3 × 107, small 110 mV/dec sub-threshold slope, and a low VD of 2.5 V for low power operation. This mobility is already better than chemical-vapor-deposition grown multi-layers MoS2 TFT. From first principle quantum-mechanical calculation, the high mobility TFT is due to strongly overlapped orbitals.

Gas-phase fragmentation of coordination compounds: loss of CO(2) from inorganic carbonato complexes to give metal oxide ions

PubMed

Dalgaard; McKenzie

1999-10-01

Using electrospray ionization mass spectrometry, novel transition metal oxide coordination complex ions are proposed as the products of the collision-induced dissociation (CID) of some carbonato complex ions through the loss of a mass equivalent to CO(2). CID spectra of [(tpa)CoCO(3)](+) (tpa = tris(2-pyridylmethyl)methylamine), [(bispicMe(2)en)Fe(&mgr;-O)(&mgr;-CO(3))Fe(bispicMe(2)en)]2+ (bispicMe(2)en = N,N'-dimethyl-N,N'-bis(2-pyridylmethy)eth- ane-1, 2-diamine) and [(bpbp)Cu(2)CO(3)](+) (bpbp(-) = bis[(bis-(2-pyridylmethyl)amino)methyl]-4-tertbutylpheno-lato(1-)), show peaks assigned to the mono- and dinuclear oxide cations, [(tpa)CoO](+), [(bispicMe(2)en)(2)Fe(2)(O)(2)]2+ and [(bpbp)Cu(2)O](+), as the dominant species. These results can be likened to the reverse of typical synthetic reactions in which metal hydroxide compounds react with CO(2) to give metal carbonato compounds. Because of the lack of available protons in the gas phase, novel oxide species rather than the more common hydroxide ions are generated. These oxide ions are relevant to the highly oxidizing species proposed in oxygenation reactions catalysed by metal oxides and metalloenzymes. Copyright 1999 John Wiley & Sons, Ltd.

Gate tunneling current and quantum capacitance in metal-oxide-semiconductor devices with graphene gate electrodes

NASA Astrophysics Data System (ADS)

An, Yanbin; Shekhawat, Aniruddh; Behnam, Ashkan; Pop, Eric; Ural, Ant

2016-11-01

Metal-oxide-semiconductor (MOS) devices with graphene as the metal gate electrode, silicon dioxide with thicknesses ranging from 5 to 20 nm as the dielectric, and p-type silicon as the semiconductor are fabricated and characterized. It is found that Fowler-Nordheim (F-N) tunneling dominates the gate tunneling current in these devices for oxide thicknesses of 10 nm and larger, whereas for devices with 5 nm oxide, direct tunneling starts to play a role in determining the total gate current. Furthermore, the temperature dependences of the F-N tunneling current for the 10 nm devices are characterized in the temperature range 77-300 K. The F-N coefficients and the effective tunneling barrier height are extracted as a function of temperature. It is found that the effective barrier height decreases with increasing temperature, which is in agreement with the results previously reported for conventional MOS devices with polysilicon or metal gate electrodes. In addition, high frequency capacitance-voltage measurements of these MOS devices are performed, which depict a local capacitance minimum under accumulation for thin oxides. By analyzing the data using numerical calculations based on the modified density of states of graphene in the presence of charged impurities, it is shown that this local minimum is due to the contribution of the quantum capacitance of graphene. Finally, the workfunction of the graphene gate electrode is extracted by determining the flat-band voltage as a function of oxide thickness. These results show that graphene is a promising candidate as the gate electrode in metal-oxide-semiconductor devices.

Aerosol chemical vapor deposition of metal oxide films

DOEpatents

Ott, K.C.; Kodas, T.T.

1994-01-11

A process of preparing a film of a multicomponent metal oxide including: forming an aerosol from a solution comprised of a suitable solvent and at least two precursor compounds capable of volatilizing at temperatures lower than the decomposition temperature of said precursor compounds; passing said aerosol in combination with a suitable oxygen-containing carrier gas into a heated zone, said heated zone having a temperature sufficient to evaporate the solvent and volatilize said precursor compounds; and passing said volatilized precursor compounds against the surface of a substrate, said substrate having a sufficient temperature to decompose said volatilized precursor compounds whereby metal atoms contained within said volatilized precursor compounds are deposited as a metal oxide film upon the substrate is disclosed. In addition, a coated article comprising a multicomponent metal oxide film conforming to the surface of a substrate selected from the group consisting of silicon, magnesium oxide, yttrium-stabilized zirconium oxide, sapphire, or lanthanum gallate, said multicomponent metal oxide film characterized as having a substantially uniform thickness upon said substrate.

Transition metal-catalyzed oxidation of sulfur(IV) oxides. Atmospheric-relevant processes and mechanisms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brandt, C.; Eldik, R. van

1995-01-01

The transition metal-catalyzed oxidation of sulfur(IV) oxides has been known for more than 100 years. There is a significant lack of information on the actual role of the transition metal-catalyzed reactions, and much of the earlier work was performed without a detailed knowledge of the chemical system. For this reason attention is focused on the role of transition metal ions in the oxidation of sulfur(IV) oxides in terms of the coordination chemistry involved, as well as the stability and chemical behavior of the various participating species. The oxidation process of sulfur(IV) oxides plays an important role in atmospheric chemistry (e.g.more » acid rain formation) as well as industrial processes (e.g. desulfurization of plume gases and ore). The present report deals with the mechanism of the transition metal-catalyzed oxidation of sulfur(IV) oxides with the aim to discuss this in terms of atmospheric and chemical processes. In addition, the authors would like to emphasize the key role of oxygen in these processes. 1,076 refs.« less

Metal ion binding to iron oxides

NASA Astrophysics Data System (ADS)

Ponthieu, M.; Juillot, F.; Hiemstra, T.; van Riemsdijk, W. H.; Benedetti, M. F.

2006-06-01

The biogeochemistry of trace elements (TE) is largely dependent upon their interaction with heterogeneous ligands including metal oxides and hydrous oxides of iron. The modeling of TE interactions with iron oxides has been pursued using a variety of chemical models. The objective of this work is to show that it is possible to model the adsorption of protons and TE on a crystallized oxide (i.e., goethite) and on an amorphous oxide (HFO) in an identical way. Here, we use the CD-MUSIC approach in combination with valuable and reliable surface spectroscopy information about the nature of surface complexes of the TE. The other objective of this work is to obtain generic parameters to describe the binding of the following elements (Cd, Co, Cu, Ni, Pb, and Zn) onto both iron oxides for the CD-MUSIC approach. The results show that a consistent description of proton and metal ion binding is possible for goethite and HFO with the same set of model parameters. In general a good prediction of almost all the collected experimental data sets corresponding to metal ion binding to HFO is obtained. Moreover, dominant surface species are in agreement with the recently published surface complexes derived from X-ray absorption spectroscopy (XAS) data. Until more detailed information on the structure of the two iron oxides is available, the present option seems a reasonable approximation and can be used to describe complex geochemical systems. To improve our understanding and modeling of multi-component systems we need more data obtained at much lower metal ion to iron oxide ratios in order to be able to account eventually for sites that are not always characterized in spectroscopic studies.

Density of states-based design of metal oxide thin-film transistors for high mobility and superior photostability.

PubMed

Kim, Hyun-Suk; Park, Joon Seok; Jeong, Hyun-Kwang; Son, Kyoung Seok; Kim, Tae Sang; Seon, Jong-Baek; Lee, Eunha; Chung, Jae Gwan; Kim, Dae Hwan; Ryu, Myungkwan; Lee, Sang Yoon

2012-10-24

A novel method to design metal oxide thin-film transistor (TFT) devices with high performance and high photostability for next-generation flat-panel displays is reported. Here, we developed bilayer metal oxide TFTs, where the front channel consists of indium-zinc-oxide (IZO) and the back channel material on top of it is hafnium-indium-zinc-oxide (HIZO). Density-of-states (DOS)-based modeling and device simulation were performed in order to determine the optimum thickness ratio within the IZO/HIZO stack that results in the best balance between device performance and stability. As a result, respective values of 5 and 40 nm for the IZO and HIZO layers were determined. The TFT devices that were fabricated accordingly exhibited mobility values up to 48 cm(2)/(V s), which is much elevated compared to pure HIZO TFTs (∼13 cm(2)/(V s)) but comparable to pure IZO TFTs (∼59 cm(2)/(V s)). Also, the stability of the bilayer device (-1.18 V) was significantly enhanced compared to the pure IZO device (-9.08 V). Our methodology based on the subgap DOS model and simulation provides an effective way to enhance the device stability while retaining a relatively high mobility, which makes the corresponding devices suitable for ultradefinition, large-area, and high-frame-rate display applications.

Method for converting uranium oxides to uranium metal

DOEpatents

Duerksen, Walter K.

1988-01-01

A process is described for converting scrap and waste uranium oxide to uranium metal. The uranium oxide is sequentially reduced with a suitable reducing agent to a mixture of uranium metal and oxide products. The uranium metal is then converted to uranium hydride and the uranium hydride-containing mixture is then cooled to a temperature less than -100.degree. C. in an inert liquid which renders the uranium hydride ferromagnetic. The uranium hydride is then magnetically separated from the cooled mixture. The separated uranium hydride is readily converted to uranium metal by heating in an inert atmosphere. This process is environmentally acceptable and eliminates the use of hydrogen fluoride as well as the explosive conditions encountered in the previously employed bomb-reduction processes utilized for converting uranium oxides to uranium metal.

Lithium metal oxide electrodes for lithium batteries

DOEpatents

Thackeray, Michael M.; Johnson, Christopher S.; Amine, Khalil; Kang, Sun-Ho

2010-06-08

An uncycled preconditioned electrode for a non-aqueous lithium electrochemical cell including a lithium metal oxide having the formula xLi.sub.2-yH.sub.yO.xM'O.sub.2.(1-x)Li.sub.1-zH.sub.zMO.sub.2 in which 0metal ion with an average trivalent oxidation state selected from two or more of the first row transition metals or lighter metal elements in the periodic table, and M' is one or more ions with an average tetravalent oxidation state selected from the first and second row transition metal elements and Sn. The xLi.sub.2-yH.sub.y.xM'O.sub.2.(1-x)Li.sub.1-zH.sub.zMO.sub.2 material is prepared by preconditioning a precursor lithium metal oxide (i.e., xLi.sub.2M'O.sub.3.(1-x)LiMO.sub.2) with a proton-containing medium with a pH<7.0 containing an inorganic acid. Methods of preparing the electrodes are disclosed, as are electrochemical cells and batteries containing the electrodes.

The lyocell process: Cellulose solutions in N-Methylmorpholine-N-oxide (NMMO) - degradation processes and stabilizers

Treesearch

Thomas Rosenau; Thomas Elder; Antje Potthast; Sixta Herbert; Paul Kosma

2003-01-01

Homolytic (radical) reactions in the system cellulose / N-methylmorpholine-N-oxide (NMMO, 1) involve a primary, nitrogen-centered cation radical (2), and two secondary, carbon-centered radical species (3, 4). Radical formation &om NMMO is strongly promoted by transition metal ions.

Solder for oxide layer-building metals and alloys

DOEpatents

Kronberg, James W.

1992-01-01

A low temperature solder and method for soldering an oxide layer-building metal such as aluminum, titanium, tantalum or stainless steel. The comosition comprises tin and zinc; germanium as a wetting agent; preferably small amounts of copper and antimony; and a grit, such as silicon carbide. The grit abrades any oxide layer formed on the surface of the metal as the germanium penetrates beneath and loosens the oxide layer to provide good metal-to-metal contact. The germanium comprises less than aproximatley 10% by weight of the solder composition so that it provides sufficient wetting action but does not result in a melting temperature above approximately 300.degree. C. The method comprises the steps rubbing the solder against the metal surface so the grit in the solder abrades the surface while heating the surface until the solder begins to melt and the germanium penetrates the oxide layer, then brushing aside any oxide layer loosened by the solder.

Solder for oxide layer-building metals and alloys

DOEpatents

Kronberg, J.W.

1992-09-15

A low temperature solder and method for soldering an oxide layer-building metal such as aluminum, titanium, tantalum or stainless steel is disclosed. The composition comprises tin and zinc; germanium as a wetting agent; preferably small amounts of copper and antimony; and a grit, such as silicon carbide. The grit abrades any oxide layer formed on the surface of the metal as the germanium penetrates beneath and loosens the oxide layer to provide good metal-to-metal contact. The germanium comprises less than approximately 10% by weight of the solder composition so that it provides sufficient wetting action but does not result in a melting temperature above approximately 300 C. The method comprises the steps rubbing the solder against the metal surface so the grit in the solder abrades the surface while heating the surface until the solder begins to melt and the germanium penetrates the oxide layer, then brushing aside any oxide layer loosened by the solder.

The β1 Subunit Enhances Oxidative Regulation of Large-Conductance Calcium-activated K+ Channels

PubMed Central

Santarelli, Lindsey Ciali; Chen, Jianguo; Heinemann, Stefan H.; Hoshi, Toshinori

2004-01-01

Oxidative stress may alter the functions of many proteins including the Slo1 large conductance calcium-activated potassium channel (BKCa). Previous results demonstrated that in the virtual absence of Ca2+, the oxidant chloramine-T (Ch-T), without the involvement of cysteine oxidation, increases the open probability and slows the deactivation of BKCa channels formed by human Slo1 (hSlo1) α subunits alone. Because native BKCa channel complexes may include the auxiliary subunit β1, we investigated whether β1 influences the oxidative regulation of hSlo1. Oxidation by Ch-T with β1 present shifted the half-activation voltage much further in the hyperpolarizing direction (−75 mV) as compared with that with α alone (−30 mV). This shift was eliminated in the presence of high [Ca2+]i, but the increase in open probability in the virtual absence of Ca2+ remained significant at physiologically relevant voltages. Furthermore, the slowing of channel deactivation after oxidation was even more dramatic in the presence of β1. Oxidation of cysteine and methionine residues within β1 was not involved in these potentiated effects because expression of mutant β1 subunits lacking cysteine or methionine residues produced results similar to those with wild-type β1. Unlike the results with α alone, oxidation by Ch-T caused a significant acceleration of channel activation only when β1 was present. The β1 M177 mutation disrupted normal channel activation and prevented the Ch-T–induced acceleration of activation. Overall, the functional effects of oxidation of the hSlo1 pore-forming α subunit are greatly amplified by the presence of β1, which leads to the additional increase in channel open probability and the slowing of deactivation. Furthermore, M177 within β1 is a critical structural determinant of channel activation and oxidative sensitivity. Together, the oxidized BKCa channel complex with β1 has a considerable chance of being open within the physiological voltage

Nanocomposite of graphene and metal oxide materials

DOEpatents

Liu, Jun; Aksay, Ilhan A.; Choi, Daiwon; Wang, Donghai; Yang, Zhenguo

2013-10-15

Nanocomposite materials comprising a metal oxide bonded to at least one graphene material. The nanocomposite materials exhibit a specific capacity of at least twice that of the metal oxide material without the graphene at a charge/discharge rate greater than about 10 C.

Nanocomposite of graphene and metal oxide materials

DOEpatents

Liu, Jun; Aksay, Ilhan A.; Choi, Daiwon; Wang, Donghai; Yang, Zhenguo

2012-09-04

Nanocomposite materials comprising a metal oxide bonded to at least one graphene material. The nanocomposite materials exhibit a specific capacity of at least twice that of the metal oxide material without the graphene at a charge/discharge rate greater than about 10C.

Nanocomposite of graphene and metal oxide materials

DOEpatents

Liu, Jun; Aksay, Ilhan A.; Choi, Daiwon; Wang, Donghai; Yang, Zhenguo

2015-06-30

Nanocomposite materials comprising a metal oxide bonded to at least one graphene material. The nanocomposite materials exhibit a specific capacity of at least twice that of the metal oxide material without the graphene at a charge/discharge rate greater than about 10 C.

Aerosol chemical vapor deposition of metal oxide films

DOEpatents

Ott, Kevin C.; Kodas, Toivo T.

1994-01-01

A process of preparing a film of a multicomponent metal oxide including: forming an aerosol from a solution comprised of a suitable solvent and at least two precursor compounds capable of volatilizing at temperatures lower than the decomposition temperature of said precursor compounds; passing said aerosol in combination with a suitable oxygen-containing carrier gas into a heated zone, said heated zone having a temperature sufficient to evaporate the solvent and volatilize said precursor compounds; and passing said volatilized precursor compounds against the surface of a substrate, said substrate having a sufficient temperature to decompose said volatilized precursor compounds whereby metal atoms contained within said volatilized precursor compounds are deposited as a metal oxide film upon the substrate is disclosed. In addition, a coated article comprising a multicomponent metal oxide film conforming to the surface of a substrate selected from the group consisting of silicon, magnesium oxide, yttrium-stabilized zirconium oxide, sapphire, or lanthanum gallate, said multicomponent metal oxide film characterized as having a substantially uniform thickness upon said FIELD OF THE INVENTION The present invention relates to the field of film coating deposition techniques, and more particularly to the deposition of multicomponent metal oxide films by aerosol chemical vapor deposition. This invention is the result of a contract with the Department of Energy (Contract No. W-7405-ENG-36).

Metals, toxicity and oxidative stress.

PubMed

Valko, M; Morris, H; Cronin, M T D

2005-01-01

Metal-induced toxicity and carcinogenicity, with an emphasis on the generation and role of reactive oxygen and nitrogen species, is reviewed. Metal-mediated formation of free radicals causes various modifications to DNA bases, enhanced lipid peroxidation, and altered calcium and sulfhydryl homeostasis. Lipid peroxides, formed by the attack of radicals on polyunsaturated fatty acid residues of phospholipids, can further react with redox metals finally producing mutagenic and carcinogenic malondialdehyde, 4-hydroxynonenal and other exocyclic DNA adducts (etheno and/or propano adducts). Whilst iron (Fe), copper (Cu), chromium (Cr), vanadium (V) and cobalt (Co) undergo redox-cycling reactions, for a second group of metals, mercury (Hg), cadmium (Cd) and nickel (Ni), the primary route for their toxicity is depletion of glutathione and bonding to sulfhydryl groups of proteins. Arsenic (As) is thought to bind directly to critical thiols, however, other mechanisms, involving formation of hydrogen peroxide under physiological conditions, have been proposed. The unifying factor in determining toxicity and carcinogenicity for all these metals is the generation of reactive oxygen and nitrogen species. Common mechanisms involving the Fenton reaction, generation of the superoxide radical and the hydroxyl radical appear to be involved for iron, copper, chromium, vanadium and cobalt primarily associated with mitochondria, microsomes and peroxisomes. However, a recent discovery that the upper limit of "free pools" of copper is far less than a single atom per cell casts serious doubt on the in vivo role of copper in Fenton-like generation of free radicals. Nitric oxide (NO) seems to be involved in arsenite-induced DNA damage and pyrimidine excision inhibition. Various studies have confirmed that metals activate signalling pathways and the carcinogenic effect of metals has been related to activation of mainly redox-sensitive transcription factors, involving NF-kappaB, AP-1 and p53

Internal zone growth method for producing metal oxide metal eutectic composites

DOEpatents

Clark, Grady W.; Holder, John D.; Pasto, Arvid E.

1980-01-01

An improved method for preparing a cermet comprises preparing a compact having about 85 to 95 percent theoretical density from a mixture of metal and metal oxide powders from a system containing a eutectic composition, and inductively heating the compact in a radiofrequency field to cause the formation of an internal molten zone. The metal oxide particles in the powder mixture are effectively sized relative to the metal particles to permit direct inductive heating of the compact by radiofrequency from room temperature. Surface melting is prevented by external cooling or by effectively sizing the particles in the powder mixture.

Transition Metal Oxides for the Oxygen Reduction Reaction: Influence of the Oxidation States of the Metal and its Position on the Periodic Table.

PubMed

Toh, Rou Jun; Sofer, Zdeněk; Pumera, Martin

2015-11-16

Electrocatalysts have been developed to meet the needs and requirements of renewable energy applications. Metal oxides have been well explored and are promising for this purpose, however, many reports focus on only one or a few metal oxides at once. Herein, thirty metal oxides, which were either commercially available or synthesized by a simple and scalable method, were screened for comparison with regards to their electrocatalytic activity towards the oxygen reduction reaction (ORR). We show that although manganese, iron, cobalt, and nickel oxides generally displayed the ability to enhance the kinetics of oxygen reduction under alkaline conditions compared with bare glassy carbon, there is no significant correlation between the position of a metal on the periodic table and the electrocatalytic performance of its respective metal oxides. Moreover, it was also observed that mixed valent (+2, +3) oxides performed the poorest, compared with their respective pure metal oxides. These findings may be of paramount importance in the field of renewable energy. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ceramic membranes having macroscopic channels

DOEpatents

Anderson, Marc A.; Peterson, Reid A.

1996-01-01

Methods have been developed to make porous ceramic membranes having macroscopic channels therethrough. The novel membranes are formed by temporarily supporting the sol-gel membrane precursor on an organic support which is ultimately removed from the interior of the membrane, preferably by pyrolysis or by chemical destruction. The organic support may also include an inorganic metal portion that remains on destruction of the organic portion, providing structural support and/or chemical reactivity to the membrane. The channels formed when the organic support is destroyed provide the ability to withdraw small catalytic products or size-separated molecules from the metal oxide membrane. In addition, the channel-containing membranes retain all of the advantages of existing porous ceramic membranes.

Ceramic membranes having macroscopic channels

DOEpatents

Anderson, M.A.; Peterson, R.A.

1996-09-03

Methods have been developed to make porous ceramic membranes having macroscopic channels therethrough. The novel membranes are formed by temporarily supporting the sol-gel membrane precursor on an organic support which is ultimately removed from the interior of the membrane, preferably by pyrolysis or by chemical destruction. The organic support may also include an inorganic metal portion that remains on destruction of the organic portion, providing structural support and/or chemical reactivity to the membrane. The channels formed when the organic support is destroyed provide the ability to withdraw small catalytic products or size-separated molecules from the metal oxide membrane. In addition, the channel-containing membranes retain all of the advantages of existing porous ceramic membranes. 1 fig.

40 CFR 721.10500 - Acrylated mixed metal oxides (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Acrylated mixed metal oxides (generic... Specific Chemical Substances § 721.10500 Acrylated mixed metal oxides (generic). (a) Chemical substance and... mixed metal oxides (PMN P-06-341) is subject to reporting under this section for the significant new...

40 CFR 721.10500 - Acrylated mixed metal oxides (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Acrylated mixed metal oxides (generic... Specific Chemical Substances § 721.10500 Acrylated mixed metal oxides (generic). (a) Chemical substance and... mixed metal oxides (PMN P-06-341) is subject to reporting under this section for the significant new...

Dimensional optimization of nanowire--complementary metal oxide--semiconductor inverter.

PubMed

Hashim, Yasir; Sidek, Othman

2013-01-01

This study is the first to demonstrate dimensional optimization of nanowire-complementary metal-oxide-semiconductor inverter. Noise margins and inflection voltage of transfer characteristics are used as limiting factors in this optimization. Results indicate that optimization depends on both dimensions ratio and digital voltage level (Vdd). Diameter optimization reveals that when Vdd increases, the optimized value of (Dp/Dn) decreases. Channel length optimization results show that when Vdd increases, the optimized value of Ln decreases and that of (Lp/Ln) increases. Dimension ratio optimization reveals that when Vdd increases, the optimized value of Kp/Kn decreases, and silicon nanowire transistor with suitable dimensions (higher Dp and Ln with lower Lp and Dn) can be fabricated.

Process for etching mixed metal oxides

DOEpatents

Ashby, Carol I. H.; Ginley, David S.

1994-01-01

An etching process using dicarboxylic and tricarboxylic acids as chelating etchants for mixed metal oxide films such as high temperature superconductors and ferroelectric materials. Undesirable differential etching rates between different metal oxides are avoided by selection of the proper acid or combination of acids. Feature sizes below one micron, excellent quality vertical edges, and film thicknesses in the 100 Angstom range may be achieved by this method.

Influence of metallic surface states on electron affinity of epitaxial AlN films

NASA Astrophysics Data System (ADS)

Mishra, Monu; Krishna, Shibin; Aggarwal, Neha; Gupta, Govind

2017-06-01

The present article investigates surface metallic states induced alteration in the electron affinity of epitaxial AlN films. AlN films grown by plasma-assisted molecular beam epitaxy system with (30% and 16%) and without metallic aluminium on the surface were probed via photoemission spectroscopic measurements. An in-depth analysis exploring the influence of metallic aluminium and native oxide on the electronic structure of the films is performed. It was observed that the metallic states pinned the Fermi Level (FL) near valence band edge and lead to the reduction of electron affinity (EA). These metallic states initiated charge transfer and induced changes in surface and interface dipoles strength. Therefore, the EA of the films varied between 0.6-1.0 eV due to the variation in contribution of metallic states and native oxide. However, the surface barrier height (SBH) increased (4.2-3.5 eV) adversely due to the availability of donor-like surface states in metallic aluminium rich films.

Self-organization of helium precipitates into elongated channels within metal nanolayers

PubMed Central

Chen, Di; Li, Nan; Yuryev, Dina; Baldwin, J. Kevin; Wang, Yongqiang; Demkowicz, Michael J.

2017-01-01

Material degradation due to precipitation of implanted helium (He) is a key concern in nuclear energy. Decades of research have mapped out the fate of He precipitates in metals, from nucleation and growth of equiaxed bubbles and voids to formation and bursting of surface blisters. By contrast, we show that He precipitates confined within nanoscale metal layers depart from their classical growth trajectories: They self-organize into elongated channels. These channels form via templated nucleation of He precipitates along layer surfaces followed by their growth and spontaneous coalescence into stable precipitate lines. The total line length and connectivity increases with the amount of implanted He, indicating that these channels ultimately interconnect into percolating “vascular” networks. Vascularized metal composites promise a transformative solution to He-induced damage by enabling in operando outgassing of He and other impurities while maintaining material integrity. PMID:29152573

Application of a mixed metal oxide catalyst to a metallic substrate

NASA Technical Reports Server (NTRS)

Sevener, Kathleen M. (Inventor); Lohner, Kevin A. (Inventor); Mays, Jeffrey A. (Inventor); Wisner, Daniel L. (Inventor)

2009-01-01

A method for applying a mixed metal oxide catalyst to a metallic substrate for the creation of a robust, high temperature catalyst system for use in decomposing propellants, particularly hydrogen peroxide propellants, for use in propulsion systems. The method begins by forming a prepared substrate material consisting of a metallic inner substrate and a bound layer of a noble metal intermediate. Alternatively, a bound ceramic coating, or frit, may be introduced between the metallic inner substrate and noble metal intermediate when the metallic substrate is oxidation resistant. A high-activity catalyst slurry is applied to the surface of the prepared substrate and dried to remove the organic solvent. The catalyst layer is then heat treated to bind the catalyst layer to the surface. The bound catalyst layer is then activated using an activation treatment and calcinations to form the high-activity catalyst system.

Method for inhibiting oxidation of metal sulfide-containing material

DOEpatents

Elsetinow, Alicia; Borda, Michael J.; Schoonen, Martin A.; Strongin, Daniel R.

2006-12-26

The present invention provides means for inhibiting the oxidation of a metal sulfide-containing material, such as ore mine waste rock or metal sulfide taiulings, by coating the metal sulfide-containing material with an oxidation-inhibiting two-tail lipid coating (12) thereon, thereby inhibiting oxidation of the metal sulfide-containing material in acid mine drainage conditions. The lipids may be selected from phospholipids, sphingolipids, glycolipids and combinations thereof.

Oxidation stress evolution and relaxation of oxide film/metal substrate system

NASA Astrophysics Data System (ADS)

Dong, Xuelin; Feng, Xue; Hwang, Keh-Chih

2012-07-01

Stresses in the oxide film/metal substrate system are crucial to the reliability of the system at high temperature. Two models for predicting the stress evolution during isothermal oxidation are proposed. The deformation of the system is depicted by the curvature for single surface oxidation. The creep strain of the oxide and metal, and the lateral growth strain of the oxide are considered. The proposed models are compared with the experimental results in literature, which demonstrates that the elastic model only considering for elastic strain gives an overestimated stress in magnitude, but the creep model is consistent with the experimental data and captures the stress relaxation phenomenon during oxidation. The effects of the parameter for the lateral growth strain rate are also analyzed.

Sustained hole inversion layer in a wide-bandgap metal-oxide semiconductor with enhanced tunnel current

NASA Astrophysics Data System (ADS)

Shoute, Gem; Afshar, Amir; Muneshwar, Triratna; Cadien, Kenneth; Barlage, Douglas

2016-02-01

Wide-bandgap, metal-oxide thin-film transistors have been limited to low-power, n-type electronic applications because of the unipolar nature of these devices. Variations from the n-type field-effect transistor architecture have not been widely investigated as a result of the lack of available p-type wide-bandgap inorganic semiconductors. Here, we present a wide-bandgap metal-oxide n-type semiconductor that is able to sustain a strong p-type inversion layer using a high-dielectric-constant barrier dielectric when sourced with a heterogeneous p-type material. A demonstration of the utility of the inversion layer was also investigated and utilized as the controlling element in a unique tunnelling junction transistor. The resulting electrical performance of this prototype device exhibited among the highest reported current, power and transconductance densities. Further utilization of the p-type inversion layer is critical to unlocking the previously unexplored capability of metal-oxide thin-film transistors, such applications with next-generation display switches, sensors, radio frequency circuits and power converters.

Sustained hole inversion layer in a wide-bandgap metal-oxide semiconductor with enhanced tunnel current

PubMed Central

Shoute, Gem; Afshar, Amir; Muneshwar, Triratna; Cadien, Kenneth; Barlage, Douglas

2016-01-01

Wide-bandgap, metal-oxide thin-film transistors have been limited to low-power, n-type electronic applications because of the unipolar nature of these devices. Variations from the n-type field-effect transistor architecture have not been widely investigated as a result of the lack of available p-type wide-bandgap inorganic semiconductors. Here, we present a wide-bandgap metal-oxide n-type semiconductor that is able to sustain a strong p-type inversion layer using a high-dielectric-constant barrier dielectric when sourced with a heterogeneous p-type material. A demonstration of the utility of the inversion layer was also investigated and utilized as the controlling element in a unique tunnelling junction transistor. The resulting electrical performance of this prototype device exhibited among the highest reported current, power and transconductance densities. Further utilization of the p-type inversion layer is critical to unlocking the previously unexplored capability of metal-oxide thin-film transistors, such applications with next-generation display switches, sensors, radio frequency circuits and power converters. PMID:26842997

Statistical analysis of relationship between negative-bias temperature instability and random telegraph noise in small p-channel metal-oxide-semiconductor field-effect transistors

NASA Astrophysics Data System (ADS)

Tega, Naoki; Miki, Hiroshi; Mine, Toshiyuki; Ohmori, Kenji; Yamada, Keisaku

2014-03-01

It is demonstrated from a statistical perspective that the generation of random telegraph noise (RTN) changes before and after the application of negative-bias temperature instability (NBTI) stress. The NBTI stress generates a large number of permanent interface traps and, at the same time, a large number of RTN traps causing temporary RTN and one-time RTN. The interface trap and the RTN trap show different features in the recovery process. That is, a re-passivation of interface states is the minor cause of the recovery after the NBTI stress, and in contrast, rapid disappearance of the temporary RTN and the one-time RTN is the main cause of the recovery. The RTN traps are less likely to become permanent. This two-type trap, namely, the interface trap and RTN trap, model simply explains NBTI degradation and recovery in scaled p-channel metal-oxide-semiconductor field-effect transistors.

Process for etching mixed metal oxides

DOEpatents

Ashby, C.I.H.; Ginley, D.S.

1994-10-18

An etching process is described using dicarboxylic and tricarboxylic acids as chelating etchants for mixed metal oxide films such as high temperature superconductors and ferroelectric materials. Undesirable differential etching rates between different metal oxides are avoided by selection of the proper acid or combination of acids. Feature sizes below one micron, excellent quality vertical edges, and film thicknesses in the 100 Angstrom range may be achieved by this method. 1 fig.

Metal Oxide Solubility and Molten Salt Corrosion.

DTIC Science & Technology

1982-03-29

METAL OXIDE SOLUBILITY AND MOLTEN SALT CORROSION .(U) MAR 82 K H STERN UNCLASSI E DL R L-4772NL EL .2. MICROCOPY RESOLUTION TEST CHART NATIONAL BURALU...21 l 7 3 ..... l DTIC NSPECT I" ’I cCPY INSECE( METAL OXIDE SOLUBILITY AND MOLTEN SALT CORROSION I. INTRODUCTION Molten ...discussed in terms of its importance to the understanding of molten salt corrosion . II. PROTECTIVE COATINGS Since most structural metals and alloys are

Polymer-assisted aqueous deposition of metal oxide films

DOEpatents

Li, DeQuan [Los Alamos, NM; Jia, Quanxi [Los Alamos, NM

2003-07-08

An organic solvent-free process for deposition of metal oxide thin films is presented. The process includes aqueous solutions of necessary metal precursors and an aqueous solution of a water-soluble polymer. After a coating operation, the resultant coating is fired at high temperatures to yield optical quality metal oxide thin films.

Modifying the catalytic and adsorption properties of metals and oxides

NASA Astrophysics Data System (ADS)

Yagodovskii, V. D.

2015-11-01

A new approach to interpreting the effect of promoters (inhibitors) of nonmetals and metals added to a host metal (catalyst) is considered. Theoretical calculations are based on a model of an actual two-dimensional electron gas and adsorbate particles. An equation is derived for the isotherm of induced adsorption on metals and semiconductors with respect to small fillings of θ ~ 0.1-0.15. The applicability of this equation is verified experimentally for metals (Ag, Pd, Cu, Fe, and Ni), graphitized ash, and semiconductor oxides Ta2O5, ZnO, and Ni. The applicability of the theoretical model of promotion is verified by the hydrogenation reaction of CO on ultradispersed nickel powder. The use of plasmachemical surface treatments of metals and oxides, accompanied by an increase in activity and variation in selectivity, are investigated based on the dehydrocyclization reactions of n-hexane and the dehydrogenation and dehydration of alcohols. It is established that such treatments for metals (Pt, Cu, Ni, and Co) raise their activity due to the growth of the number of active centers upon an increase in the activation energy. Applying XPES and XRD methods to metallic catalysts, it is shown that the rise in activity is associated with a change in their surface states (variation in the structural characteristics of metal particles and localization of certain forms of carbon in catalytically active centers). It is shown that plasmachemical treatments also alter their surface composition, surface activity, and raise their activity when used with complex phosphate oxides of the NASICON type. It is shown by the example of conversion of butanol-2 that abrupt variations in selectivity (prevalence of dehydration over dehydrogenation and vice versa) occur, depending on the type of plasma. It is concluded that plasmachemical treatments of metals and ZnO and NiO alter the isosteric heats and entropies of adsorption of isopropanol.

Self-organization of helium precipitates into elongated channels within metal nanolayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Di; Li, Nan; Yuryev, Dina

Material degradation due to precipitation of implanted helium (He) is a key concern in nuclear energy. Decades of research have mapped out the fate of He precipitates in metals, from nucleation and growth of equiaxed bubbles and voids to formation and bursting of surface blisters. By contrast, we show that He precipitates confined within nanoscale metal layers depart from their classical growth trajectories: They self-organize into elongated channels. These channels form via templated nucleation of He precipitates along layer surfaces followed by their growth and spontaneous coalescence into stable precipitate lines. The total line length and connectivity increases with themore » amount of implanted He, indicating that these channels ultimately interconnect into percolating “vascular” networks. In conclusion, vascularized metal composites promise a transformative solution to He-induced damage by enabling in operando outgassing of He and other impurities while maintaining material integrity.« less

Self-organization of helium precipitates into elongated channels within metal nanolayers

DOE PAGES

Chen, Di; Li, Nan; Yuryev, Dina; ...

2017-11-10

Material degradation due to precipitation of implanted helium (He) is a key concern in nuclear energy. Decades of research have mapped out the fate of He precipitates in metals, from nucleation and growth of equiaxed bubbles and voids to formation and bursting of surface blisters. By contrast, we show that He precipitates confined within nanoscale metal layers depart from their classical growth trajectories: They self-organize into elongated channels. These channels form via templated nucleation of He precipitates along layer surfaces followed by their growth and spontaneous coalescence into stable precipitate lines. The total line length and connectivity increases with themore » amount of implanted He, indicating that these channels ultimately interconnect into percolating “vascular” networks. In conclusion, vascularized metal composites promise a transformative solution to He-induced damage by enabling in operando outgassing of He and other impurities while maintaining material integrity.« less

Kinetics of abiotic nitrous oxide production via oxidation of hydroxylamine by particulate metals in seawater

NASA Astrophysics Data System (ADS)

Cavazos, A. R.; Taillefert, M.; Glass, J. B.

2016-12-01

The oceans are a significant of nitrous oxide (N2O) to the atmosphere. Current models of global oceanic N2­O flux focus on microbial N2O cycling and often ignore abiotic reactions, such as the thermodynamically favorable oxidation of the nitrification intermediate hydroxylamine (NH2OH) by Mn(IV) or Fe(III). At circumneutral pH, NH2OH oxidation is more thermodynamically favorable via Mn(IV) than Fe(III) reduction. We characterized the kinetics of NH2OH oxidation in synthetic ocean water at pH 5.1-8.8 using microsensor electrodes to measure real-time N2O production. N2O production rates and yield were greater when NH2OH was oxidized by Mn(IV) than Fe(III). Accordingly, the reduction of Mn(IV) was first order with respect to NH2OH whereas the reduction of Fe(III) was zero order with respect to NH2OH. Interestingly, the order of the reaction with respect to Mn(IV) appears to be negative whereas the reaction is second order with respect to Fe(III). The inverse order with respect to Mn(IV) may be due to the aggregation of particles in seawater, which decreases their surface area and changes their reactivity. Finally, the reaction is first order with respect to protons with Fe(III) as the oxidant but zero order with Mn(IV). The stronger effect of the pH on the reaction with Fe(III) as the oxidant compared to Mn(IV) reflects the stoichiometry of these two reactions, as each mole of N2O produced by Fe(III) reduction consumes eight protons while each mole of N2O produced with Mn(IV) as the oxidant requires only four protons. Our data show that abiotic NH2OH oxidation by Mn(IV) or Fe(III) particles may represent a significant source of N2O in seawater. These findings suggest that abiotic N2O production in marine waters may be significant in areas of the oceans where particulate metals originating from aerosols, dust, or rivers may react with NH2OH released from ammonia-oxidizing microorganisms.

Remarkably high mobility ultra-thin-film metal-oxide transistor with strongly overlapped orbitals

PubMed Central

Wei Shih, Chen; Chin, Albert; Fu Lu, Chun; Fang Su, Wei

2016-01-01

High mobility channel thin-film-transistor (TFT) is crucial for both display and future generation integrated circuit. We report a new metal-oxide TFT that has an ultra-thin 4.5 nm SnO2 thickness for both active channel and source-drain regions, very high 147 cm2/Vs field-effect mobility, high ION/IOFF of 2.3 × 107, small 110 mV/dec sub-threshold slope, and a low VD of 2.5 V for low power operation. This mobility is already better than chemical-vapor-deposition grown multi-layers MoS2 TFT. From first principle quantum-mechanical calculation, the high mobility TFT is due to strongly overlapped orbitals. PMID:26744240

Characterization of N-polar AlN in GaN/AlN/(Al,Ga)N heterostructures grown by metal-organic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Li, Haoran; Mazumder, Baishakhi; Bonef, Bastien; Keller, Stacia; Wienecke, Steven; Speck, James S.; Denbaars, Steven P.; Mishra, Umesh K.

2017-11-01

In GaN/(Al,Ga)N high-electron-mobility transistors (HEMT), AlN interlayer between GaN channel and AlGaN barrier suppresses alloy scattering and significantly improves the electron mobility of the two-dimensional electron gas. While high concentrations of gallium were previously observed in Al-polar AlN interlayers grown by metal-organic chemical vapor deposition, the N-polar AlN (Al x Ga1-x N) films examined by atom probe tomography in this study exhibited aluminum compositions (x) equal to or higher than 95% over a wide range of growth conditions. The also investigated AlN interlayer in a N-polar GaN/AlN/AlGaN/ S.I. GaN HEMT structure possessed a similarly high x content.

Electrochromic device containing metal oxide nanoparticles and ultraviolet blocking material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia, Guillermo; Koo, Bonil; Gregoratto, Ivano

An electrochromic device includes a nanostructured transition metal oxide bronze layer that includes one or more transition metal oxide and one or more dopant. The electrochromic device also includes nanoparticles containing one or more transparent conducting oxide (TCO), a solid state electrolyte, a counter electrode, and at least one protective layer to prevent degradation of the one or more nanostructured transition metal oxide bronze. The nanostructured transition metal oxide bronze selectively modulates transmittance of near-infrared (NIR) and visible radiation as a function of an applied voltage to the device.

Method for making monolithic metal oxide aerogels

DOEpatents

Droege, M.W.; Coronado, P.R.; Hair, L.M.

1995-03-07

Transparent, monolithic metal oxide aerogels of varying densities are produced using a method in which a metal alkoxide solution and a catalyst solution are prepared separately and reacted. The resulting hydrolyzed-condensed colloidal solution is gelled, and the wet gel is contained within a sealed, but gas permeable, containment vessel during supercritical extraction of the solvent. The present invention is especially advantageous for making metal oxides other than silica that are prone to forming opaque, cracked aerogels. 6 figs.

Method for making monolithic metal oxide aerogels

DOEpatents

Droege, Michael W.; Coronado, Paul R.; Hair, Lucy M.

1995-01-01

Transparent, monolithic metal oxide aerogels of varying densities are produced using a method in which a metal alkoxide solution and a catalyst solution are prepared separately and reacted. The resulting hydrolyzed-condensed colloidal solution is gelled, and the wet gel is contained within a sealed, but gas permeable, containment vessel during supercritical extraction of the solvent. The present invention is especially advantageous for making metal oxides other than silica that are prone to forming opaque, cracked aerogels.

Conductive metal oxide film and method of making

DOE Office of Scientific and Technical Information (OSTI.GOV)

Windisch, C.F. Jr.; Exarhos, G.J.

1999-11-23

The present invention is a method for reducing a dopant in a film of a metal oxide wherein the dopant is reduced and the first metal oxide is substantially not reduced. The method of the present invention relies upon exposing the film to reducing conditions for a predetermined time and reducing a valence of the metal from a positive valence to a zero valence and maintaining atoms with a zero valence in an atomic configuration within the lattice structure of the metal oxide. According to the present invention, exposure to reducing conditions may be achieved electrochemically or achieved in anmore » elevated temperature gas phase.« less

Conductive metal oxide film and method of making

DOEpatents

Windisch, Jr., Charles F.; Exarhos, Gregory J.

1999-01-01

The present invention is a method for reducing a dopant in a film of a metal oxide wherein the dopant is reduced and the first metal oxide is substantially not reduced. The method of the present invention relies upon exposing the film to reducing conditions for a predetermined time and reducing a valence of the metal from a positive valence to a zero valence and maintaining atoms with a zero valence in an atomic configuration within the lattice structure of the metal oxide. According to the present invention, exposure to reducing conditions may be achieved electrochemically or achieved in an elevated temperature gas phase.

Synthesis of metal-metal oxide catalysts and electrocatalysts using a metal cation adsorption/reduction and adatom replacement by more noble ones

DOEpatents

Adzic, Radoslav; Vukmirovic, Miomir; Sasaki, Kotaro

2010-04-27

The invention relates to platinum-metal oxide composite particles and their use as electrocatalysts in oxygen-reducing cathodes and fuel cells. The invention particularly relates to methods for preventing the oxidation of the platinum electrocatalyst in the cathodes of fuel cells by use of these platinum-metal oxide composite particles. The invention additionally relates to methods for producing electrical energy by supplying such a fuel cell with an oxidant, such as oxygen, and a fuel source, such as hydrogen. The invention also relates to methods of making the metal-metal oxide composites.

The AMOS cell - An improved metal-semiconductor solar cell. [Antireflection coated Metal Oxide Semiconductor

NASA Technical Reports Server (NTRS)

Stirn, R. J.; Yeh, Y.-C. M.

1975-01-01

A new fabrication process is being developed which significantly improves the efficiency of metal-semiconductor solar cells. The resultant effect, a marked increase in the open-circuit voltage, is produced by the addition of an interfacial layer oxide on the semiconductor. Cells using gold on n-type gallium arsenide have been made in small areas (0.17 sq cm) with conversion efficiencies of 15% in terrestrial sunlight.

Electron mobility in InGaN channel heterostructure field effect transistor structures with different barriers

NASA Astrophysics Data System (ADS)

Xie, J.; Leach, J. H.; Ni, X.; Wu, M.; Shimada, R.; Özgür, Ü.; Morkoç, H.

2007-12-01

InGaN possesses higher electron mobility and velocity than GaN, and therefore is expected to lead to relatively better performances for heterostructure field effect transistors (HFETs). However, the reported mobilities for AlGaN /InGaN HFETs are lower than GaN channel HFETs. To address this issue, we studied the effect of different barriers on the Hall mobility for InGaN channel HFETs grown by metal organic chemical vapor deposition. Unlike the conventional AlGaN barrier, the AlInN barrier can be grown at the same temperature as the InGaN channel layer, alleviating some of the technological roadblocks. Specifically, this avoids possible degradation of the thin InGaN channel during AlGaN growth at high temperatures; and paves the way for better interfaces. An undoped In0.18Al0.82N/AlN/In0.04Ga0.96N HFET structure exhibited a μH=820cm2/Vs, with a ns=2.12×1013cm-2 at room temperature. Moreover, with an In-doped AlGaN barrier, namely, Al0.24In0.01Ga0.75N, grown at 900°C, the μH increased to 1230cm2/Vs with a ns of 1.09×1013cm-2 for a similar InGaN channel. Furthermore, when the barrier was replaced by Al0.25Ga0.75N grown at 1030°C, μH dropped to 870cm2/Vs with ns of 1.26×1013cm-2 at room temperature. Our results suggest that to fully realize the potential of the InGaN channel HFETs, AlInN or AlInGaN should be used as the barrier instead of the conventional AlGaN barrier.

Method of producing solution-derived metal oxide thin films

DOEpatents

Boyle, Timothy J.; Ingersoll, David

2000-01-01

A method of preparing metal oxide thin films by a solution method. A .beta.-metal .beta.-diketonate or carboxylate compound, where the metal is selected from groups 8, 9, 10, 11, and 12 of the Periodic Table, is solubilized in a strong Lewis base to form a homogeneous solution. This precursor solution forms within minutes and can be deposited on a substrate in a single layer or a multiple layers to form a metal oxide thin film. The substrate with the deposited thin film is heated to change the film from an amorphous phase to a ceramic metal oxide and cooled.

Molecular electrocatalysts for oxidation of hydrogen using earth-abundant metals: shoving protons around with proton relays.

PubMed

Bullock, R Morris; Helm, Monte L

2015-07-21

Sustainable, carbon-neutral energy is needed to supplant the worldwide reliance on fossil fuels in order to address the persistent problem of increasing emissions of CO2. Solar and wind energy are intermittent, highlighting the need to develop energy storage on a huge scale. Electrocatalysts provide a way to convert between electrical energy generated by renewable energy sources and chemical energy in the form of chemical bonds. Oxidation of hydrogen to give two electrons and two protons is carried out in fuel cells, but the typical catalyst is platinum, a precious metal of low earth abundance and high cost. In nature, hydrogenases based on iron or iron/nickel reversibly oxidize hydrogen with remarkable efficiencies and rates. Functional models of these enzymes have been synthesized with the goal of achieving electrocatalytic H2 oxidation using inexpensive, earth-abundant metals along with a key feature identified in the [FeFe]-hydrogenase: an amine base positioned near the metal. The diphosphine ligands P(R)2N(R')2 (1,5-diaza-3,7-diphosphacyclooctane with alkyl or aryl groups on the P and N atoms) are used as ligands in Ni, Fe, and Mn complexes. The pendant amines facilitate binding and heterolytic cleavage of H2, placing the hydride on the metal and the proton on the amine. The pendant amines also serve as proton relays, accelerating intramolecular and intermolecular proton transfers. Electrochemical oxidations and deprotonations by an exogeneous amine base lead to catalytic cycles for oxidation of H2 (1 atm) at room temperature for catalysts derived from [Ni(P(Cy)2N(R')2)2](2+), Cp(C6F5)Fe(P(tBu)2N(Bn)2)H, and MnH(P(Ph)2N(Bn)2)(bppm)(CO) [bppm = (PAr(F)2)2CH2]. In the oxidation of H2 catalyzed by [Ni(P(Cy)2N(R')2)2](2+), the initial product observed experimentally is a Ni(0) complex in which two of the pendant amines are protonated. Two different pathways can occur from this intermediate; deprotonation followed by oxidation occurs with a lower overpotential than

Fluorine and oxygen plasma influence on nanoparticle formation and aggregation in metal oxide thin film transistors

NASA Astrophysics Data System (ADS)

MÄ dzik, Mateusz; Elamurugu, Elangovan; Viegas, Jaime

2017-03-01

Despite recent advances in metal oxide thin-film transistor technology, there are no foundry processes available yet for large-scale deployment of metal oxide electronics and photonics, in a similar way as found for silicon based electronics and photonics. One of the biggest challenges of the metal oxide platform is the stability of the fabricated devices. Also, there is wide dispersion on the measured specifications of fabricated TFT, from lot-to-lot and from different research groups. This can be partially explained by the importance of the deposition method and its parameters, which determine thin film microstructure and thus its electrical properties. Furthermore, substrate pretreatment is an important factor, as it may act as a template for material growth. Not so often mentioned, plasma processes can also affect the morphology of deposited films on further deposition steps, such as inducing nanoparticle formation, which strongly impact the conduction mechanism in the channel layer of the TFT. In this study, molybdenum doped indium oxide is sputtered onto ALD deposited HfO2 with or without pattering, and etched by RIE chlorine based processing. Nanoparticle formation is observed when photoresist is removed by oxygen plasma ashing. HfO2 etching in CF4/Ar plasma prior to resist stripping in oxygen plasma promotes the aggregation of nanoparticles into nanosized branched structures. Such nanostructuring is absent when oxygen plasma steps are replaced by chemical wet processing with acetone. Finally, in order to understand the electronic transport effect of the nanoparticles on metal oxide thin film transistors, TFT have been fabricated and electrically characterized.

Microscale Soft Patterning for Solution Processable Metal Oxide Thin Film Transistors.

PubMed

Jung, Sang Wook; Chae, Soo Sang; Park, Jee Ho; Oh, Jin Young; Bhang, Suk Ho; Baik, Hong Koo; Lee, Tae Il

2016-03-23

We introduce a microscale soft pattering (MSP) route utilizing contact printing of chemically inert sub-nanometer thick low molecular weight (LMW) poly(dimethylsiloxane) (PDMS) layers. These PDMS layers serve as a release agent layer between the n-type Ohmic metal and metal oxide semiconductors (MOSs) and provide a layer that protects the MOS from water in the surrounding environment. The feasibility of our MSP route was experimentally demonstrated by fabricating solution processable In2O3, IZO, and IGZO TFTs with aluminum (Al), a typical n-type Ohmic metal. We have demonstrated patterning gaps as small as 13 μm. The TFTs fabricated using MSP showed higher field-effect-mobility and lower hysteresis in comparison with those made using conventional photolithography.

High-Resolution Inkjet-Printed Oxide Thin-Film Transistors with a Self-Aligned Fine Channel Bank Structure.

PubMed

Zhang, Qing; Shao, Shuangshuang; Chen, Zheng; Pecunia, Vincenzo; Xia, Kai; Zhao, Jianwen; Cui, Zheng

2018-05-09

A self-aligned inkjet printing process has been developed to construct small channel metal oxide (a-IGZO) thin-film transistors (TFTs) with independent bottom gates on transparent glass substrates. Poly(methylsilsesquioxane) was used to pattern hydrophobic banks on the transparent substrate instead of commonly used self-assembled octadecyltrichlorosilane. Photolithographic exposure from backside using bottom-gate electrodes as mask formed hydrophilic channel areas for the TFTs. IGZO ink was selectively deposited by an inkjet printer in the hydrophilic channel region and confined by the hydrophobic bank structure, resulting in the precise deposition of semiconductor layers just above the gate electrodes. Inkjet-printed IGZO TFTs with independent gate electrodes of 10 μm width have been demonstrated, avoiding completely printed channel beyond the broad of the gate electrodes. The TFTs showed on/off ratios of 10 8 , maximum mobility of 3.3 cm 2 V -1 s -1 , negligible hysteresis, and good uniformity. This method is conductive to minimizing the area of printed TFTs so as to the development of high-resolution printing displays.

Effect of Alkali Metal Cations on Slow Inactivation of Cardiac Na+ Channels

PubMed Central

Townsend, Claire; Horn, Richard

1997-01-01

Human heart Na+ channels were expressed transiently in both mammalian cells and Xenopus oocytes, and Na+ currents measured using 150 mM intracellular Na+. The kinetics of decaying outward Na+ current in response to 1-s depolarizations in the F1485Q mutant depends on the predominant cation in the extracellular solution, suggesting an effect on slow inactivation. The decay rate is lower for the alkali metal cations Li+, Na+, K+, Rb+, and Cs+ than for the organic cations Tris, tetramethylammonium, N-methylglucamine, and choline. In whole cell recordings, raising [Na+]o from 10 to 150 mM increases the rate of recovery from slow inactivation at −140 mV, decreases the rate of slow inactivation at relatively depolarized voltages, and shifts steady-state slow inactivation in a depolarized direction. Single channel recordings of F1485Q show a decrease in the number of blank (i.e., null) records when [Na+]o is increased. Significant clustering of blank records when depolarizing at a frequency of 0.5 Hz suggests that periods of inactivity represent the sojourn of a channel in a slow-inactivated state. Examination of the single channel kinetics at +60 mV during 90-ms depolarizations shows that neither open time, closed time, nor first latency is significantly affected by [Na+]o. However raising [Na+]o decreases the duration of the last closed interval terminated by the end of the depolarization, leading to an increased number of openings at the depolarized voltage. Analysis of single channel data indicates that at a depolarized voltage a single rate constant for entry into a slow-inactivated state is reduced in high [Na+]o, suggesting that the binding of an alkali metal cation, perhaps in the ion-conducting pore, inhibits the closing of the slow inactivation gate. PMID:9234168

New reactions involving the oxidative O-, N-, and C-phosphorylation of organic compounds by phosphorus and phosphides in the presence of metal complexes

NASA Astrophysics Data System (ADS)

Dorfman, Ya A.; Aleshkova, M. M.; Polimbetova, G. S.; Levina, L. V.; Petrova, T. V.; Abdreimova, R. R.; Doroshkevich, D. M.

1993-09-01

The mechanisms of new catalytic reactions leading to the formation of di-, and tri-alkyl phosphates, di- and tri-alkyl phosphites, phosphoramidites, phosphazenes, phosphines, and phosphine oxides from hydrogen, copper, and zinc phosphides and white and red phosphorus are analysed. The mechanisms of the activation of the reactants by metal complexes and of the reactions involving the oxidative P-O, P-N, and P-C coupling of organic compounds to phosphorus and phosphides are considered. The bibliography includes 124 references.

Solar photocatalytic water oxidation over Ag3PO4/g-C3N4 composite materials mediated by metallic Ag and graphene

NASA Astrophysics Data System (ADS)

Cui, Xingkai; Tian, Lin; Xian, Xiaozhai; Tang, Hua; Yang, Xiaofei

2018-02-01

Solar-driven water splitting over semiconductor-based photocatalysts provides direct conversion of solar energy to chemical energy, in which electron-hole separation and charge transport are critical for enhancing the photocatalytic activity of semiconducting materials. Moreover, the search for active photocatalysts that efficiently oxidize water remains a challenging task. Here, we demonstrate that a series of Ag3PO4/Ag/graphene/graphitic carbon nitride (g-C3N4) heterostructured materials can drive photocatalytic water oxidation efficiently under LED illumination. The water oxidation behavior of as-prepared composite photocatalysts in relation to the added amount of g-C3N4 and the roles of electron mediators was investigated in detail. Based on the illuminated Z-scheme photocatalytic mechanism, the photogenerated electrons and holes can be separated effectively and the electron-hole recombination of bulk material is suppressed. The reduced metallic Ag nanoparticles were found to function as the center for the accumulation of electrons from Ag3PO4 and holes from g-C3N4. By exploiting the proper addition of g-C3N4 into the composite, photocatalytic oxygen evolution performance over the heterostructured materials could be suitably tuned, which resulted in highly efficient water oxidation.

Method of producing adherent metal oxide coatings on metallic surfaces

DOEpatents

Lane, Michael H.; Varrin, Jr., Robert D.

2001-01-01

Provided is a process of producing an adherent synthetic corrosion product (sludge) coating on metallic surfaces. The method involves a chemical reaction between a dry solid powder mixture of at least one reactive metal oxide with orthophosphoric acid to produce a coating in which the particles are bound together and the matrix is adherent to the metallic surface.

Process for making surfactant capped metal oxide nanocrystals, and products produced by the process

DOEpatents

Alivisatos, A. Paul; Rockenberger, Joerg

2006-01-10

Disclosed is a process for making surfactant capped nanocrystals of metal oxides which are dispersable in organic solvents. The process comprises decomposing a metal cupferron complex of the formula M^XCup_X, wherein M is a metal, and Cup is a N-substituted N-Nitroso hydroxylamine, in the presence of a coordinating surfactant, the reaction being conducted at a temperature ranging from about 150 to about 400.degree. C., for a period of time sufficient to complete the reaction. Also disclosed are compounds made by the process.

Metal Oxide/Graphene Composites for Supercapacitive Electrode Materials.

PubMed

Jeong, Gyoung Hwa; Baek, Seungmin; Lee, Seungyeol; Kim, Sang-Wook

2016-04-05

Graphene composites with metal or metal oxide nanoparticles have been extensively investigated owing to their potential applications in the fields of fuel cells, batteries, sensing, solar cells, and catalysis. Among them, much research has focused on supercapacitor applications and have come close to realization. Composites include monometal oxides of cobalt, nickel, manganese, and iron, as well as their binary and ternary oxides. In addition, their morphological control and hybrid systems of carbon nanotubes have also been investigated. This review presents the current trends in research on metal oxide/graphene composites for supercapacitors. Furthermore, methods are suggested to improve the properties of electrochemical capacitor electrodes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optimization of the Solution-Based Indium-Zinc Oxide/Zinc-Tin Oxide Channel Layer for Thin-Film Transistors.

PubMed

Lim, Kiwon; Choi, Pyungho; Kim, Sangsub; Kim, Hyunki; Kim, Minsoo; Lee, Jeonghyun; Hyeon, Younghwan; Koo, Kwangjun; Choi, Byoungdeog

2018-09-01

Double stacked indium-zinc oxide (IZO)/zinc-tin oxide (ZTO) active layers were employed in amorphous-oxide-semiconductor thin-film transistors (AOS TFTs). Channel layers of the TFTs were optimized by varying the molarity of ZTO back channel layers (0.05, 0.1, 0.2, 0.3 M) and the electrical properties of IZO/ZTO double stacked TFTs were compared to single IZO and ZTO TFTs with varying the molarity and molar ratio. On the basis of the results, IZO/ZTO (0.1 M) TFTs showed the excellent electrical properties of saturation mobility (13.6 cm2/V·s), on-off ratio (7×106), and subthreshold swing (0.223 V/decade) compared to ZTO (0.1 M) of 0.73 cm2/V · s, 1 × 107, 0.416 V/decade and IZO (0.04 M) of 0.10 cm2/V · s, 5 × 106, 0.60 V/decade, respectively. This may be attributed to diffusing Sn into front layer during annealing process. In addition, with varying molarity of ZTO back channel layer, from 0.1 M to 0.3 M ZTO back channel TFTs, electrical properties and positive bias stability deteriorated with increasing molarity of back channel layer because of increasing total trap states. On the other hand, 0.05 M ZTO back channel TFT had inferior electrical properties than that of 0.1 M ZTO back channel TFT. It was related to back channel effect because of having thin thickness of channel layer. Among these devices, 0.1 M ZTO back channel TFT had a lowest total trap density, outstanding electrical properties and stability. Therefore, we recommended IZO/ZTO (0.1 M) TFT as a promising channel structure for advanced display applications.

Reduction of aqueous transition metal species on the surfaces of Fe(II)-containing oxides

USGS Publications Warehouse

White, A.F.; Peterson, M.L.

1996-01-01

Experimental studies demonstrate that structural Fe(II) in magnetite and ilmenite heterogeneously reduce aqueous ferric, cupric, vanadate, and chromate ions at the oxide surfaces over a pH range of 1-7 at 25??C. For an aqueous transition metal m, such reactions are 3[Fe2+Fe3+2]O4(magnetite) + 2/nmz ??? 4[Fe3+2]O3(maghemite) + Fe2+ + 2/nmz-n and 3[Fe2+Ti]O3(ilmenite) + 2/nmz ??? Fe3+2Ti3O9(pseudorutile) + Fe2+ + 2/nmz-n, where z is the valance state and n is the charge transfer number. The half cell potential range for solid state oxidation [Fe(II)] ??? [Fe(III)] is -0.34 to -0.65 V, making structural Fe(II) a stronger reducing agent than aqueous Fe2+ (-0.77 V). Reduction rates for aqueous metal species are linear with time (up to 36 h), decrease with pH, and have rate constants between 0.1 and 3.3 ?? 10-10 mol m-2 s-1. Iron is released to solution both from the above reactions and from dissolution of the oxide surface. In the presence of chromate, Fe2+ is oxidized homogeneously in solution to Fe3+. X-ray photoelectron spectroscopy (XPS) denotes a Fe(III) oxide surface containing reduced Cr(III) and V(IV) species. Magnetite and ilmenite electrode potentials are insensitive to increases in divalent transition metals including Zn(II), Co(II), Mn(II), and Ni(II) and reduced V(IV) and Cr(III) but exhibit a log-linear concentration-potential response to Fe(III) and Cu(II). Complex positive electrode responses occur with increasing Cr(VI) and V(V) concentrations. Potential dynamic scans indicate that the high oxidation potential of dichromate is capable of suppressing the cathodic reductive dissolution of magnetite. Oxide electrode potentials are determined by the Fe(II)/Fe(III) composition of the oxide surface and respond to aqueous ion potentials which accelerate this oxidation process. Natural magnetite sands weathered under anoxic conditions are electrochemically reactive as demonstrated by rapid chromate reduction and the release of aqueous Fe(III) to experimental

Metal oxide porous ceramic membranes with small pore sizes

DOEpatents

Anderson, Marc A.; Xu, Qunyin

1992-01-01

A method is disclosed for the production of metal oxide ceramic membranes of very small pore size. The process is particularly useful in the creation of titanium and other transition metal oxide membranes. The method utilizes a sol-gel process in which the rate of particle formation is controlled by substituting a relatively large alcohol in the metal alkoxide and by limiting the available water. Stable, transparent metal oxide ceramic membranes are created having a narrow distribution of pore size, with the pore diameter being manipulable in the range of 5 to 40 Angstroms.

Metal oxide porous ceramic membranes with small pore sizes

DOEpatents

Anderson, Marc A.; Xu, Qunyin

1991-01-01

A method is disclosed for the production of metal oxide ceramic membranes of very small pore size. The process is particularly useful in the creation of titanium and other transition metal oxide membranes. The method utilizes a sol-gel process in which the rate of particle formation is controlled by substituting a relatively large alcohol in the metal alkoxide and by limiting the available water. Stable, transparent metal oxide ceramic membranes are created having a narrow distribution of pore size, with the pore diameter being manipulable in the range of 5 to 40 Angstroms.

N-acetylcysteine-induced vasodilation involves voltage-gated potassium channels in rat aorta.

PubMed

Han, Wei-Qing; Zhu, Ding-Liang; Wu, Ling-Yun; Chen, Qi-Zhi; Guo, Shu-Jie; Gao, Ping-Jin

2009-05-22

N-acetylcysteine (NAC) has a protective effect against vascular dysfunction by decreasing the level of reactive oxygen species (ROS) in experimental and human hypertension. This study was designed to examine whether NAC would relax vascular rings in vitro via nitric oxide-cyclic guanosine monophosphate (NO-cGMP) pathway, extracellular Ca2+ and/or K+ channels. Rat aortic arteries were mounted in an organ bath, contracted with 0.1, 0.5 or 1 micromol/L phenylephrine to plateau, and the vasodilatory effect of NAC was examined in the absence or presence of ROS scavengers, inhibitors of NO-cGMP pathway or K+ channels. Vascular smooth muscle cells (VSMCs) were loaded with a calcium sensitive fluorescent dye fluo-3 AM, and [Ca2+](i) was determined with laser-scanning confocal microscopy. NAC (0.1-4 mmol/L) dose-dependently relaxed rat aorta pre-contracted with phenylephrine. Endothelium removal, endothelial nitric oxide synthase inhibitor N(omega)-Nitro-l-arginine (L-NNA) (100 micromol/L) or soluble guanylyl cyclase (sGC) inhibitor (ODQ) (10 micromol/L) did not affect NAC-induced vasodilation. In contrast, NAC-induced vasodilation was blunted after extracellular calcium was removed and calcium imaging showed that 4 mmol/L NAC quickly decreased [Ca2+](i) in fluo-3 AM loaded VSMCs. NAC-induced vasodilation was significantly reduced in the presence of voltage-gated K+ channels (Kv) inhibitor 4-aminopyridine (4-AP). The vasodilatory effect of NAC may be explained at least partly by activation of voltage-gated K+ channels.

Electrical and structural characterization of IZO (indium oxide-zinc oxide) thin films for device applications

NASA Astrophysics Data System (ADS)

Yaglioglu, Burag

Materials for oxide-based transparent electronics have been recently reported in the literature. These materials include various amorphous and crystalline compounds based on multi-component oxides and many of them offer useful combinations of transparency, controllable carrier concentrations, and reasonable n-carrier mobility. In this thesis, the properties of amorphous and crystalline In2O3-10wt%ZnO, IZO, thin films were investigated for their potential use in oxide electronics. The room temperature deposition of this material using DC magnetron sputtering results in the formation of amorphous films. Annealing amorphous IZO films at 500°C in air produces a previously unknown crystalline compound. Using electron diffraction experiments, it is reported that the crystal structure of this compound is based on the high-pressure rhombohedral phase of In2O3. Electrical properties of different phases of IZO were explored and it was concluded that amorphous films offer most promising characteristics for device applications. Therefore, thin film transistors (TFT) were fabricated based on amorphous IZO films where both the channel and metallization layers were deposited from the same target. The carrier densities in the channel and source-drain layers were adjusted by changing the oxygen content in the sputter chamber during deposition. The resulting transistors operate as depletion mode n-channel field effect devices with high saturation mobilities.

Metal contact engineering and registration-free fabrication of complementary metal-oxide semiconductor integrated circuits using aligned carbon nanotubes.

PubMed

Wang, Chuan; Ryu, Koungmin; Badmaev, Alexander; Zhang, Jialu; Zhou, Chongwu

2011-02-22

Complementary metal-oxide semiconductor (CMOS) operation is very desirable for logic circuit applications as it offers rail-to-rail swing, larger noise margin, and small static power consumption. However, it remains to be a challenging task for nanotube-based devices. Here in this paper, we report our progress on metal contact engineering for n-type nanotube transistors and CMOS integrated circuits using aligned carbon nanotubes. By using Pd as source/drain contacts for p-type transistors, small work function metal Gd as source/drain contacts for n-type transistors, and evaporated SiO(2) as a passivation layer, we have achieved n-type transistor, PN diode, and integrated CMOS inverter with an air-stable operation. Compared with other nanotube n-doping techniques, such as potassium doping, PEI doping, hydrazine doping, etc., using low work function metal contacts for n-type nanotube devices is not only air stable but also integrated circuit fabrication compatible. Moreover, our aligned nanotube platform for CMOS integrated circuits shows significant advantage over the previously reported individual nanotube platforms with respect to scalability and reproducibility and suggests a practical and realistic approach for nanotube-based CMOS integrated circuit applications.

Role of metal oxides in chemical evolution

NASA Astrophysics Data System (ADS)

Kamaluddin

2013-06-01

Steps of chemical evolution have been designated as formation of biomonomers followed by their polymerization and then to modify in an organized structure leading to the formation of first living cell. Formation of small molecules like amino acids, organic bases, sugar etc. could have occurred in the reducing atmosphere of the primitive Earth. Polymerization of these small molecules could have required some catalyst. In addition to clay, role of metal ions and metal complexes as prebiotic catalyst in the synthesis and polymerization of biomonomers cannot be ruled out. Metal oxides are important constituents of Earth crust and that of other planets. These oxides might have adsorbed organic molecules and catalyzed the condensation processes, which may have led to the formation of first living cell. Different studies were performed in order to investigate the role of metal oxides (especially oxides of iron and manganese) in chemical evolution. Iron oxides (goethite, akaganeite and hematite) as well as manganese oxides (MnO, Mn2O3, Mn3O4 and MnO2) were synthesized and their characterization was done using IR, powder XRD, FE-SEM and TEM. Role of above oxides was studied in the adsorption of ribose nucleotides, formation of nucleobases from formamide and oligomerization of amino acids. Above oxides of iron and manganese were found to have good adsorption affinity towards ribose nucleotides, high catalytic activity in the formation of several nucleobases from formamide and oligomerization of glycine and alanine. Characterization of products was performed using UV, IR, HPLC and ESI-MS techniques. Presence of hematite-water system on Mars has been suggested to be a positive indicator in the chemical evolution on Mars.

Method for producing nanostructured metal-oxides

DOEpatents

Tillotson, Thomas M.; Simpson, Randall L.; Hrubesh, Lawrence W.; Gash, Alexander

2006-01-17

A synthetic route for producing nanostructure metal-oxide-based materials using sol-gel processing. This procedure employs the use of stable and inexpensive hydrated-metal inorganic salts and environmentally friendly solvents such as water and ethanol. The synthesis involves the dissolution of the metal salt in a solvent followed by the addition of a proton scavenger, which induces gel formation in a timely manner. Both critical point (supercritical extraction) and atmospheric (low temperature evaporation) drying may be employed to produce monolithic aerogels and xerogels, respectively. Using this method synthesis of metal-oxide nanostructured materials have been carried out using inorganic salts, such as of Fe.sup.3+, Cr.sup.3+, Al.sup.3+, Ga.sup.3+, In.sup.3+, Hf.sup.4+, Sn.sup.4+, Zr.sup.4+, Nb.sup.5+, W.sup.6+, Pr.sup.3+, Er.sup.3+, Nd.sup.3+, Ce.sup.3+, U.sup.3+ and Y.sup.3+. The process is general and nanostructured metal-oxides from the following elements of the periodic table can be made: Groups 2 through 13, part of Group 14 (germanium, tin, lead), part of Group 15 (antimony, bismuth), part of Group 16 (polonium), and the lanthanides and actinides. The sol-gel processing allows for the addition of insoluble materials (e.g., metals or polymers) to the viscous sol, just before gelation, to produce a uniformly distributed nanocomposites upon gelation. As an example, energetic nanocomposites of Fe.sub.xO.sub.y gel with distributed Al metal are readily made. The compositions are stable, safe, and can be readily ignited to thermitic reaction.

Bi–Mn mixed metal organic oxide: A novel 3d-6p mixed metal coordination network

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Fa-Nian, E-mail: fshi@ua.pt; Department of Chemistry, CICECO, University of Aveiro, 3810-193 Aveiro; Rosa Silva, Ana

2015-05-15

A new terminology of metal organic oxide (MOO) was given a definition as a type of coordination polymers which possess the feature of inorganic connectivity between metals and the direct bonded atoms and show 1D, 2D or 3D inorganic sub-networks. One such compound was shown as an example. A 3d-6p (Mn–Bi. Named MOOMnBi) mixed metals coordination network has been synthesized via hydrothermal method. The new compound with the molecular formula of [MnBi{sub 2}O(1,3,5-BTC){sub 2}]{sub n} (1,3,5-BTC stands for benzene-1,3,5-tricarboxylate) was characterized via single crystal X-ray diffraction technique that revealed a very interesting 3-dimensional (3D) framework with Bi{sub 4}O{sub 2}(COO){sub 12}more » clusters which are further connected to Mn(COO){sub 6} fragments into a 2D MOO. The topology study indicates an unprecedented topological type with the net point group of (4{sup 13}.6{sup 2})(4{sup 13}.6{sup 8})(4{sup 16}.6{sup 5})(4{sup 18}.6{sup 10})(4{sup 22}.6{sup 14})(4{sup 3}) corresponding to 3,6,7,7,8,9-c hexa-nodal net. MOOMnBi shows catalytic activity in the synthesis of (E)-α,β-unsaturated ketones. - Graphical abstract: This metal organic framework (MOF) is the essence of a 2D metal organic oxide (MOO). - Highlights: • New concept of metal organic oxide (MOO) was defined and made difference from metal organic framework. • New MOO of MOOMnBi was synthesized by hydrothermal method. • Crystal structure of MOOMnBi was determined by single crystal X-ray analysis. • The catalytic activity of MOOMnBi was studied showing reusable after 2 cycles.« less

40 CFR 721.5315 - Nickel, cobalt mixed metal oxide (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Nickel, cobalt mixed metal oxide... Specific Chemical Substances § 721.5315 Nickel, cobalt mixed metal oxide (generic). (a) Chemical substance... nickel, cobalt mixed metal oxide. (PMN P-02-90) is subject to reporting under this section for the...

40 CFR 721.5315 - Nickel, cobalt mixed metal oxide (generic).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Nickel, cobalt mixed metal oxide... Specific Chemical Substances § 721.5315 Nickel, cobalt mixed metal oxide (generic). (a) Chemical substance... nickel, cobalt mixed metal oxide. (PMN P-02-90) is subject to reporting under this section for the...

40 CFR 721.5315 - Nickel, cobalt mixed metal oxide (generic).

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Nickel, cobalt mixed metal oxide... Specific Chemical Substances § 721.5315 Nickel, cobalt mixed metal oxide (generic). (a) Chemical substance... nickel, cobalt mixed metal oxide. (PMN P-02-90) is subject to reporting under this section for the...

40 CFR 721.5315 - Nickel, cobalt mixed metal oxide (generic).

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Nickel, cobalt mixed metal oxide... Specific Chemical Substances § 721.5315 Nickel, cobalt mixed metal oxide (generic). (a) Chemical substance... nickel, cobalt mixed metal oxide. (PMN P-02-90) is subject to reporting under this section for the...

Using Dopants to Tune Oxygen Vacancy Formation in Transition Metal Oxide Resistive Memory.

PubMed

Jiang, Hao; Stewart, Derek A

2017-05-17

Introducing dopants is an important way to tailor and improve electronic properties of transition metal oxides used as high-k dielectric thin films and resistance switching layers in leading memory technologies, such as dynamic and resistive random access memory (ReRAM). Ta 2 O 5 has recently received increasing interest because Ta 2 O 5 -based ReRAM demonstrates high switching speed, long endurance, and low operating voltage. However, advances in optimizing device characteristics with dopants have been hindered by limited and contradictory experiments in this field. We report on a systematic study on how various metal dopants affect oxygen vacancy formation in crystalline and amorphous Ta 2 O 5 from first principles. We find that isoelectronic dopants and weak n-type dopants have little impact on neutral vacancy formation energy and that p-type dopants can lower the formation energy significantly by introducing holes into the system. In contrast, n-type dopants have a deleterious effect and actually increase the formation energy for charged oxygen vacancies. Given the similar doping trend reported for other binary transition metal oxides, this doping trend should be universally valid for typical binary transition metal oxides. Based on this guideline, we propose that p-type dopants (Al, Hf, Zr, and Ti) can lower the forming/set voltage and improve retention properties of Ta 2 O 5 ReRAM.

Atomic Layer Deposition of Gallium Oxide Films as Gate Dielectrics in AlGaN/GaN Metal-Oxide-Semiconductor High-Electron-Mobility Transistors

NASA Astrophysics Data System (ADS)

Shih, Huan-Yu; Chu, Fu-Chuan; Das, Atanu; Lee, Chia-Yu; Chen, Ming-Jang; Lin, Ray-Ming

2016-04-01

In this study, films of gallium oxide (Ga2O3) were prepared through remote plasma atomic layer deposition (RP-ALD) using triethylgallium and oxygen plasma. The chemical composition and optical properties of the Ga2O3 thin films were investigated; the saturation growth displayed a linear dependence with respect to the number of ALD cycles. These uniform ALD films exhibited excellent uniformity and smooth Ga2O3-GaN interfaces. An ALD Ga2O3 film was then used as the gate dielectric and surface passivation layer in a metal-oxide-semiconductor high-electron-mobility transistor (MOS-HEMT), which exhibited device performance superior to that of a corresponding conventional Schottky gate HEMT. Under similar bias conditions, the gate leakage currents of the MOS-HEMT were two orders of magnitude lower than those of the conventional HEMT, with the power-added efficiency enhanced by up to 9 %. The subthreshold swing and effective interfacial state density of the MOS-HEMT were 78 mV decade-1 and 3.62 × 1011 eV-1 cm-2, respectively. The direct-current and radio-frequency performances of the MOS-HEMT device were greater than those of the conventional HEMT. In addition, the flicker noise of the MOS-HEMT was lower than that of the conventional HEMT.

Synthesis of Mesoporous Metal Oxides by Structure Replication: Thermal Analysis of Metal Nitrates in Porous Carbon Matrices

PubMed Central

Weinberger, Christian; Roggenbuck, Jan; Hanss, Jan; Tiemann, Michael

2015-01-01

A variety of metal nitrates were filled into the pores of an ordered mesoporous CMK-3 carbon matrix by solution-based impregnation. Thermal conversion of the metal nitrates into the respective metal oxides, and subsequent removal of the carbon matrix by thermal combustion, provides a versatile means to prepare mesoporous metal oxides (so-called nanocasting). This study aims to monitor the thermally induced processes by thermogravimetric analysis (TGA), coupled with mass ion detection (MS). The highly dispersed metal nitrates in the pores of the carbon matrix tend to react to the respective metal oxides at lower temperature than reported in the literature for pure, i.e., carbon-free, metal nitrates. The subsequent thermal combustion of the CMK-3 carbon matrix also occurs at lower temperature, which is explained by a catalytic effect of the metal oxides present in the pores. This catalytic effect is particularly strong for oxides of redox active metals, such as transition group VII and VIII metals (Mn, Fe, Co, Ni), Cu, and Ce. PMID:28347073

Water Oxidation Mechanisms of Metal Oxide Catalysts by Vibrational Spectroscopy of Transient Intermediates.

PubMed

Zhang, Miao; Frei, Heinz

2017-05-05

Water oxidation is an essential reaction of an artificial photosystem for solar fuel generation because it provides electrons needed to reduce carbon dioxide or protons to a fuel. Earth-abundant metal oxides are among the most attractive catalytic materials for this reaction because of their robustness and scalability, but their efficiency poses a challenge. Knowledge of catalytic surface intermediates gained by vibrational spectroscopy under reaction conditions plays a key role in uncovering kinetic bottlenecks and provides a basis for catalyst design improvements. Recent dynamic infrared and Raman studies reveal the molecular identity of transient surface intermediates of water oxidation on metal oxides. Combined with ultrafast infrared observations of how charges are delivered to active sites of the metal oxide catalyst and drive the multielectron reaction, spectroscopic advances are poised to play a key role in accelerating progress toward improved catalysts for artificial photosynthesis.

Nanostructured Metal Oxides and Sulfides for Lithium-Sulfur Batteries.

PubMed

Liu, Xue; Huang, Jia-Qi; Zhang, Qiang; Mai, Liqiang

2017-05-01

Lithium-sulfur (Li-S) batteries with high energy density and long cycle life are considered to be one of the most promising next-generation energy-storage systems beyond routine lithium-ion batteries. Various approaches have been proposed to break down technical barriers in Li-S battery systems. The use of nanostructured metal oxides and sulfides for high sulfur utilization and long life span of Li-S batteries is reviewed here. The relationships between the intrinsic properties of metal oxide/sulfide hosts and electrochemical performances of Li-S batteries are discussed. Nanostructured metal oxides/sulfides hosts used in solid sulfur cathodes, separators/interlayers, lithium-metal-anode protection, and lithium polysulfides batteries are discussed respectively. Prospects for the future developments of Li-S batteries with nanostructured metal oxides/sulfides are also discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Metal Oxide Gas Sensors: Sensitivity and Influencing Factors

PubMed Central

Wang, Chengxiang; Yin, Longwei; Zhang, Luyuan; Xiang, Dong; Gao, Rui

2010-01-01

Conductometric semiconducting metal oxide gas sensors have been widely used and investigated in the detection of gases. Investigations have indicated that the gas sensing process is strongly related to surface reactions, so one of the important parameters of gas sensors, the sensitivity of the metal oxide based materials, will change with the factors influencing the surface reactions, such as chemical components, surface-modification and microstructures of sensing layers, temperature and humidity. In this brief review, attention will be focused on changes of sensitivity of conductometric semiconducting metal oxide gas sensors due to the five factors mentioned above. PMID:22294916

Emerging Applications of Liquid Metals Featuring Surface Oxides

PubMed Central

2014-01-01

Gallium and several of its alloys are liquid metals at or near room temperature. Gallium has low toxicity, essentially no vapor pressure, and a low viscosity. Despite these desirable properties, applications calling for liquid metal often use toxic mercury because gallium forms a thin oxide layer on its surface. The oxide interferes with electrochemical measurements, alters the physicochemical properties of the surface, and changes the fluid dynamic behavior of the metal in a way that has, until recently, been considered a nuisance. Here, we show that this solid oxide “skin” enables many new applications for liquid metals including soft electrodes and sensors, functional microcomponents for microfluidic devices, self-healing circuits, shape-reconfigurable conductors, and stretchable antennas, wires, and interconnects. PMID:25283244

Existence of efficient divalent metal ion-catalyzed and inefficient divalent metal ion-independent channels in reactions catalyzed by a hammerhead ribozyme

PubMed Central

Zhou, Jing-Min; Zhou, De-Min; Takagi, Yasuomi; Kasai, Yasuhiro; Inoue, Atsushi; Baba, Tadashi; Taira, Kazunari

2002-01-01

The hammerhead ribozyme is generally accepted as a well characterized metalloenzyme. However, the precise nature of the interactions of the RNA with metal ions remains to be fully defined. Examination of metal ion-catalyzed hammerhead reactions at limited concentrations of metal ions is useful for evaluation of the role of metal ions, as demonstrated in this study. At concentrations of Mn2+ ions from 0.3 to 3 mM, addition of the ribozyme to the reaction mixture under single-turnover conditions enhances the reaction with the product reaching a fixed maximum level. Further addition of the ribozyme inhibits the reaction, demonstrating that a certain number of divalent metal ions is required for proper folding and also for catalysis. At extremely high concentrations, monovalent ions, such as Na+ ions, can also serve as cofactors in hammerhead ribozyme-catalyzed reactions. However, the catalytic efficiency of monovalent ions is extremely low and, thus, high concentrations are required. Furthermore, addition of monovalent ions to divalent metal ion-catalyzed hammerhead reactions inhibits the divalent metal ion-catalyzed reactions, suggesting that the more desirable divalent metal ion–ribozyme complexes are converted to less desirable monovalent metal ion–ribozyme complexes via removal of divalent metal ions, which serve as a structural support in the ribozyme complex. Even though two channels appear to exist, namely an efficient divalent metal ion-catalyzed channel and an inefficient monovalent metal ion-catalyzed channel, it is clear that, under physiological conditions, hammerhead ribozymes are metalloenzymes that act via the significantly more efficient divalent metal ion-dependent channel. Moreover, the observed kinetic data are consistent with Lilley’s and DeRose’s two-phase folding model that was based on ground state structure analyses. PMID:12034824

Strengthening of metallic alloys with nanometer-size oxide dispersions

DOEpatents

Flinn, J.E.; Kelly, T.F.

1999-06-01

Austenitic stainless steels and nickel-base alloys containing, by wt. %, 0.1 to 3.0% V, 0.01 to 0.08% C, 0.01 to 0.5% N, 0.05% max. each of Al and Ti, and 0.005 to 0.10% O, are strengthened and ductility retained by atomization of a metal melt under cover of an inert gas with added oxygen to form approximately 8 nanometer-size hollow oxides within the alloy grains and, when the alloy is aged, strengthened by precipitation of carbides and nitrides nucleated by the hollow oxides. Added strengthening is achieved by nitrogen solid solution strengthening and by the effect of solid oxides precipitated along and pinning grain boundaries to provide temperature-stabilization and refinement of the alloy grains. 20 figs.

Strengthening of metallic alloys with nanometer-size oxide dispersions

DOEpatents

Flinn, John E.; Kelly, Thomas F.

1999-01-01

Austenitic stainless steels and nickel-base alloys containing, by wt. %, 0.1 to 3.0% V, 0.01 to 0.08% C, 0.01 to 0.5% N, 0.05% max. each of Al and Ti, and 0.005 to 0.10% O, are strengthened and ductility retained by atomization of a metal melt under cover of an inert gas with added oxygen to form approximately 8 nanometer-size hollow oxides within the alloy grains and, when the alloy is aged, strengthened by precipitation of carbides and nitrides nucleated by the hollow oxides. Added strengthening is achieved by nitrogen solid solution strengthening and by the effect of solid oxides precipitated along and pinning grain boundaries to provide temperature-stabilization and refinement of the alloy grains.

Dynamical coupled-channels study of pi N --> pi pi N reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kamano, Hiroyuki; Julia Diaz, Bruno; Lee, Tsung-Shung

2009-01-01

As a step toward performing a complete coupled-channels analysis of the world data of pi N, gamma^* N --> pi N, eta N, pi pi N reactions, the pi N --> pi pi N reactions are investigated starting with the dynamical coupled-channels model developed in Phys. Rev. C76, 065201 (2007). The channels included are pi N, eta N, and pi pi N which has pi Delta, rho N, and sigma N resonant components. The non-resonant amplitudes are generated from solving a set of coupled-channels equations with the meson-baryon potentials defined by effective Lagrangians. The resonant amplitudes are generated from 16more » bare excited nucleon (N^*) states which are dressed by the non-resonant interactions as constrained by the unitarity condition. The available total cross section data of pi^+ p --> pi^+ pi^+ n, pi^+ pi^0 and pi^- p --> pi^+ pi^- n, pi^- pi^0 n, pi^0 pi^0 n can be reproduced to a very large extent both in magnitudes and energy-dependence. Possible improvements of the model are investigated, in p« less

Creating Lithium-Ion Electrolytes with Biomimetic Ionic Channels in Metal-Organic Frameworks.

PubMed

Shen, Li; Wu, Hao Bin; Liu, Fang; Brosmer, Jonathan L; Shen, Gurong; Wang, Xiaofeng; Zink, Jeffrey I; Xiao, Qiangfeng; Cai, Mei; Wang, Ge; Lu, Yunfeng; Dunn, Bruce

2018-06-01

Solid-state electrolytes are the key to the development of lithium-based batteries with dramatically improved energy density and safety. Inspired by ionic channels in biological systems, a novel class of pseudo solid-state electrolytes with biomimetic ionic channels is reported herein. This is achieved by complexing the anions of an electrolyte to the open metal sites of metal-organic frameworks (MOFs), which transforms the MOF scaffolds into ionic-channel analogs with lithium-ion conduction and low activation energy. This work suggests the emergence of a new class of pseudo solid-state lithium-ion conducting electrolytes. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of techniques for processing metal-metal oxide systems

NASA Technical Reports Server (NTRS)

Johnson, P. C.

1976-01-01

Techniques for producing model metal-metal oxide systems for the purpose of evaluating the results of processing such systems in the low-gravity environment afforded by a drop tower facility are described. Because of the lack of success in producing suitable materials samples and techniques for processing in the 3.5 seconds available, the program was discontinued.

Metal/metal oxide doped oxide catalysts having high deNOx selectivity for lean NOx exhaust aftertreatment systems

DOEpatents

Park, Paul W.

2004-03-16

A lean NOx catalyst and method of preparing the same is disclosed. The lean NOx catalyst includes a ceramic substrate, an oxide support material, preferably .gamma.-alumina, deposited on the substrate and a metal promoter or dopant introduced into the oxide support material. The metal promoters or dopants are selected from the group consisting of indium, gallium, tin, silver, germanium, gold, nickel, cobalt, copper, iron, manganese, molybdenum, chromium, cerium, vanadium, oxides thereof, and combinations thereof. The .gamma.-alumina preferably has a pore volume of from about 0.5 to about 2.0 cc/g; a surface area of between about 80 to 350 m.sup.2 /g; an average pore size diameter of between about 3 to 30 nm; and an impurity level of less than or equal to 0.2 weight percent. In a preferred embodiment the .gamma.-alumina is prepared by a sol-gel method, with the metal doping of the .gamma.-alumina preferably accomplished using an incipient wetness impregnation technique.

Isolation and characterization of nanosheets containing few layers of the Aurivillius family of oxides and metal-organic compounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sreedhara, M.B.; Prasad, B.E.; Moirangthem, Monali

2015-04-15

Nanosheets containing few-layers of ferroelectric Aurivillius family of oxides, Bi{sub 2}A{sub n−1}B{sub n}O{sub 3n+3} (where A=Bi{sup 3+}, Ba{sup 2+} etc. and B=Ti{sup 4+}, Fe{sup 3+} etc.) with n=3, 4, 5, 6 and 7 have been prepared by reaction with n-butyllithium, followed by exfoliation in water. The few-layer samples have been characterized by Tyndall cones, atomic force microscopy, optical spectroscopy and other techniques. The few-layer species have a thickness corresponding to a fraction of the c-parameter along which axis the perovskite layers are stacked. Magnetization measurements have been carried out on the few-layer samples containing iron. Few-layer species of a fewmore » layered metal-organic compounds have been obtained by ultrasonication and characterized by Tyndall cones, atomic force microscopy, optical spectroscopy and magnetic measurements. Significant changes in the optical spectra and magnetic properties are found in the few-layer species compared to the bulk samples. Few-layer species of the Aurivillius family of oxides may find uses as thin layer dielectrics in photovoltaics and other applications. - Graphical abstract: Exfoliation of the layered Aurivillius oxides into few-layer nanosheets by chemical Li intercalation using n-BuLi followed by reaction in water. Exfoliation of the layered metal-organic compounds into few-layer nanosheets by ultrasonication. - Highlights: • Few-layer nanosheets of Aurivillius family of oxides with perovskite layers have been generated by lithium intercalation. • Few-layer nanosheets of few layered metal-organic compounds have been generated by ultrasonication. • Few-layer nanosheets of the Aurivillius oxides have been characterized by AFM, TEM and optical spectroscopy. • Aurivillius oxides containing Fe show layer dependent magnetic properties. • Exfoliated few-layer metal-organic compounds show changes in spectroscopic and magnetic properties compared with bulk materials.« less

Synthesis, structural characterization and selectively catalytic properties of metal-organic frameworks with nano-sized channels: A modular design strategy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qiu Lingguang; Gu Lina; Hu Gang

2009-03-15

Modular design method for designing and synthesizing microporous metal-organic frameworks (MOFs) with selective catalytical activity was described. MOFs with both nano-sized channels and potential catalytic activities could be obtained through self-assembly of a framework unit and a catalyst unit. By selecting hexaaquo metal complexes and the ligand BTC (BTC=1,3,5-benzenetricarboxylate) as framework-building blocks and using the metal complex [M(phen){sub 2}(H{sub 2}O){sub 2}]{sup 2+} (phen=1,10-phenanthroline) as a catalyst unit, a series of supramolecular MOFs 1-7 with three-dimensional nano-sized channels, i.e. [M{sup 1}(H{sub 2}O){sub 6}].[M{sup 2}(phen){sub 2}(H{sub 2}O){sub 2}]{sub 2}.2(BTC).xH{sub 2}O (M{sup 1}, M{sup 2}=Co(II), Ni(II), Cu(II), Zn(II), or Mn(II), phen=1,10-phenanthroline, BTC=1,3,5-benzenetricarboxylate, x=22-24),more » were synthesized through self-assembly, and their structures were characterized by IR, elemental analysis, and single-crystal X-ray diffraction. These supramolecular microporous MOFs showed significant size and shape selectivity in the catalyzed oxidation of phenols, which is due to catalytic reactions taking place in the channels of the framework. Design strategy, synthesis, and self-assembly mechanism for the construction of these porous MOFs were discussed. - Grapical abstract: A modular design strategy has been developed to synthesize microporous metal-organic frameworks with potential catalytic activity by self-assembly of the framework-building blocks and the catalyst unit.« less

Plasmonically sensitized metal-oxide electron extraction layers for organic solar cells.

PubMed

Trost, S; Becker, T; Zilberberg, K; Behrendt, A; Polywka, A; Heiderhoff, R; Görrn, P; Riedl, T

2015-01-16

ZnO and TiOx are commonly used as electron extraction layers (EELs) in organic solar cells (OSCs). A general phenomenon of OSCs incorporating these metal-oxides is the requirement to illuminate the devices with UV light in order to improve device characteristics. This may cause severe problems if UV to VIS down-conversion is applied or if the UV spectral range (λ < 400 nm) is blocked to achieve an improved device lifetime. In this work, silver nanoparticles (AgNP) are used to plasmonically sensitize metal-oxide based EELs in the vicinity (1-20 nm) of the metal-oxide/organic interface. We evidence that plasmonically sensitized metal-oxide layers facilitate electron extraction and afford well-behaved highly efficient OSCs, even without the typical requirement of UV exposure. It is shown that in the plasmonically sensitized metal-oxides the illumination with visible light lowers the WF due to desorption of previously ionosorbed oxygen, in analogy to the process found in neat metal oxides upon UV exposure, only. As underlying mechanism the transfer of hot holes from the metal to the oxide upon illumination with hν < Eg is verified. The general applicability of this concept to most common metal-oxides (e.g. TiOx and ZnO) in combination with different photoactive organic materials is demonstrated.

Defect Chemistry and Plasmon Physics of Colloidal Metal Oxide Nanocrystals.

PubMed

Lounis, Sebastien D; Runnerstrom, Evan L; Llordés, Anna; Milliron, Delia J

2014-05-01

Plasmonic nanocrystals of highly doped metal oxides have seen rapid development in the past decade and represent a class of materials with unique optoelectronic properties. In this Perspective, we discuss doping mechanisms in metal oxides and the accompanying physics of free carrier scattering, both of which have implications in determining the properties of localized surface plasmon resonances (LSPRs) in these nanocrystals. The balance between activation and compensation of dopants limits the free carrier concentration of the most common metal oxides, placing a ceiling on the LSPR frequency. Furthermore, because of ionized impurity scattering of the oscillating plasma by dopant ions, scattering must be treated in a fundamentally different way in semiconductor metal oxide materials when compared with conventional metals. Though these effects are well-understood in bulk metal oxides, further study is needed to understand their manifestation in nanocrystals and corresponding impact on plasmonic properties, and to develop materials that surpass current limitations in free carrier concentration.

Synthesis of Lithium Metal Oxide Nanoparticles by Induction Thermal Plasmas.

PubMed

Tanaka, Manabu; Kageyama, Takuya; Sone, Hirotaka; Yoshida, Shuhei; Okamoto, Daisuke; Watanabe, Takayuki

2016-04-06

Lithium metal oxide nanoparticles were synthesized by induction thermal plasma. Four different systems-Li-Mn, Li-Cr, Li-Co, and Li-Ni-were compared to understand formation mechanism of Li-Me oxide nanoparticles in thermal plasma process. Analyses of X-ray diffractometry and electron microscopy showed that Li-Me oxide nanoparticles were successfully synthesized in Li-Mn, Li-Cr, and Li-Co systems. Spinel structured LiMn₂O₄ with truncated octahedral shape was formed. Layer structured LiCrO₂ or LiCoO₂ nanoparticles with polyhedral shapes were also synthesized in Li-Cr or Li-Co systems. By contrast, Li-Ni oxide nanoparticles were not synthesized in the Li-Ni system. Nucleation temperatures of each metal in the considered system were evaluated. The relationship between the nucleation temperature and melting and boiling points suggests that the melting points of metal oxides have a strong influence on the formation of lithium metal oxide nanoparticles. A lower melting temperature leads to a longer reaction time, resulting in a higher fraction of the lithium metal oxide nanoparticles in the prepared nanoparticles.

Multiscale model of metal alloy oxidation at grain boundaries

NASA Astrophysics Data System (ADS)

Sushko, Maria L.; Alexandrov, Vitaly; Schreiber, Daniel K.; Rosso, Kevin M.; Bruemmer, Stephen M.

2015-06-01

High temperature intergranular oxidation and corrosion of metal alloys is one of the primary causes of materials degradation in nuclear systems. In order to gain insights into grain boundary oxidation processes, a mesoscale metal alloy oxidation model is established by combining quantum Density Functional Theory (DFT) and mesoscopic Poisson-Nernst-Planck/classical DFT with predictions focused on Ni alloyed with either Cr or Al. Analysis of species and fluxes at steady-state conditions indicates that the oxidation process involves vacancy-mediated transport of Ni and the minor alloying element to the oxidation front and the formation of stable metal oxides. The simulations further demonstrate that the mechanism of oxidation for Ni-5Cr and Ni-4Al is qualitatively different. Intergranular oxidation of Ni-5Cr involves the selective oxidation of the minor element and not matrix Ni, due to slower diffusion of Ni relative to Cr in the alloy and due to the significantly smaller energy gain upon the formation of nickel oxide compared to that of Cr2O3. This essentially one-component oxidation process results in continuous oxide formation and a monotonic Cr vacancy distribution ahead of the oxidation front, peaking at alloy/oxide interface. In contrast, Ni and Al are both oxidized in Ni-4Al forming a mixed spinel NiAl2O4. Different diffusivities of Ni and Al give rise to a complex elemental distribution in the vicinity of the oxidation front. Slower diffusing Ni accumulates in the oxide and metal within 3 nm of the interface, while Al penetrates deeper into the oxide phase. Ni and Al are both depleted from the region 3-10 nm ahead of the oxidation front creating voids. The oxide microstructure is also different. Cr2O3 has a plate-like structure with 1.2-1.7 nm wide pores running along the grain boundary, while NiAl2O4 has 1.5 nm wide pores in the direction parallel to the grain boundary and 0.6 nm pores in the perpendicular direction providing an additional pathway for oxygen

Electrical hysteresis in p-GaN metal-oxide-semiconductor capacitor with atomic-layer-deposited Al2O3 as gate dielectric

NASA Astrophysics Data System (ADS)

Zhang, Kexiong; Liao, Meiyong; Imura, Masataka; Nabatame, Toshihide; Ohi, Akihiko; Sumiya, Masatomo; Koide, Yasuo; Sang, Liwen

2016-12-01

The electrical hysteresis in current-voltage (I-V) and capacitance-voltage characteristics was observed in an atomic-layer-deposited Al2O3/p-GaN metal-oxide-semiconductor capacitor (PMOSCAP). The absolute minimum leakage currents of the PMOSCAP for forward and backward I-V scans occurred not at 0 V but at -4.4 and +4.4 V, respectively. A negative flat-band voltage shift of 5.5 V was acquired with a capacitance step from +4.4 to +6.1 V during the forward scan. Mg surface accumulation on p-GaN was demonstrated to induce an Mg-Ga-Al-O oxidized layer with a trap density on the order of 1013 cm-2. The electrical hysteresis is attributed to the hole trapping and detrapping process in the traps of the Mg-Ga-Al-O layer via the Poole-Frenkel mechanism.

Metal oxide electrocatalysts for alternative energy technologies

NASA Astrophysics Data System (ADS)

Pacquette, Adele Lawren

This dissertation focuses on the development of metal oxide electrocatalysts with varying applications for alternative energy technologies. Interest in utilizing clean, renewable and sustainable sources of energy for powering the planet in the future has received much attention. This will address the growing concern of the need to reduce our dependence on fossil fuels. The facile synthesis of metal oxides from earth abundant metals was explored in this work. The electrocatalysts can be incorporated into photoelectrochemical devices, fuel cells, and other energy storage devices. The first section addresses the utilization of semiconductors that can harness solar energy for water splitting to generate hydrogen. An oxysulfide was studied in order to combine the advantageous properties of the stability of metal oxides and the visible light absorbance of metal chalcogenides. Bi 2O2S was synthesized under facile hydrothermal conditions. The band gap of Bi2O2S was smaller than that of its oxide counterpart, Bi2O3. Light absorption by Bi 2O2S was extended to the visible region (>600 nm) in comparison to Bi2O3. The formation of a composite with In 2O3 was formed in order to create a UV irradiation protective coating of the Bi2O2S. The Bi2O2S/In 2O3 composite coupled with a dye CrTPP(Cl) and cocatalysts Pt and Co3O4 was utilized for water splitting under light irradiation to generate hydrogen and oxygen. The second section focuses on improving the stability and light absorption of semiconductors by changing the shapes and morphologies. One of the limitations of semiconductor materials is that recombination of electron-hole pairs occur within the bulk of the materials instead of migration to the surface. Three-dimensional shapes, such as nanorods, can prevent this recombination in comparison to spherical particles. Hierarchical structures, such as dendrites, cubes, and multipods, were synthesized under hydrothermal conditions, in order to reduce recombination and improve

Assessment of the Phytotoxicity of Metal Oxide Nanoparticles on Two Crop Plants, Maize (Zea mays L.) and Rice (Oryza sativa L.).

PubMed

Yang, Zhongzhou; Chen, Jing; Dou, Runzhi; Gao, Xiang; Mao, Chuanbin; Wang, Li

2015-11-30

In this study, the phytotoxicity of seven metal oxide nanoparticles(NPs)-titanium dioxide (nTiO₂), silicon dioxide (nSiO₂), cerium dioxide (nCeO₂), magnetite (nFe₃O₄), aluminum oxide (nAl₂O₃), zinc oxide (nZnO) and copper oxide (nCuO)-was assessed on two agriculturally significant crop plants (maize and rice). The results showed that seed germination was not affected by any of the seven metal oxide NPs. However, at the concentration of 2000 mg·L(-1), the root elongation was significantly inhibited by nCuO (95.73% for maize and 97.28% for rice), nZnO (50.45% for maize and 66.75% for rice). On the contrary, minor phytotoxicity of nAl₂O₃ was only observed in maize, and no obvious toxic effects were found in the other four metal oxide NPs. By further study we found that the phytotoxic effects of nZnO, nAl₂O₃ and nCuO (25 to 2000 mg·L(-)¹) were concentration dependent, and were not caused by the corresponding Cu(2+), Zn(2+) and Al(3+) ions (0.11 mg·L(-)¹, 1.27 mg·L(-)¹ and 0.74 mg·L(-)¹, respectively). Furthermore, ZnO NPs (<50 nm) showed greater toxicity than ZnO microparticles(MPs)(<5 μm) to root elongation of both maize and rice. Overall, this study provided valuable information for the application of engineered NPs in agriculture and the assessment of the potential environmental risks.

Method of adhesion between an oxide layer and a metal layer

DOEpatents

Jennison, Dwight R.; Bogicevic, Alexander; Kelber, Jeffry A.; Chambers, Scott A.

2004-09-14

A method of controlling the wetting characteristics and increasing the adhesion between a metal and an oxide layer. By introducing a negatively-charged species to the surface of an oxide layer, layer-by-layer growth of metal deposited onto the oxide surface is promoted, increasing the adhesion strength of the metal-oxide interface. The negatively-charged species can either be deposited onto the oxide surface or a compound can be deposited that dissociates on, or reacts with, the surface to form the negatively-charged species. The deposited metal adatoms can thereby bond laterally to the negatively-charged species as well as vertically to the oxide surface as well as react with the negatively charged species, be oxidized, and incorporated on or into the surface of the oxide.

Amorphous semiconducting and conducting transparent metal oxide thin films and production thereof

DOEpatents

Perkins, John; Van Hest, Marinus Franciscus Antonius Maria; Ginley, David; Taylor, Matthew; Neuman, George A.; Luten, Henry A.; Forgette, Jeffrey A.; Anderson, John S.

2010-07-13

Metal oxide thin films and production thereof are disclosed. An exemplary method of producing a metal oxide thin film may comprise introducing at least two metallic elements and oxygen into a process chamber to form a metal oxide. The method may also comprise depositing the metal oxide on a substrate in the process chamber. The method may also comprise simultaneously controlling a ratio of the at least two metallic elements and a stoichiometry of the oxygen during deposition. Exemplary amorphous metal oxide thin films produced according to the methods herein may exhibit highly transparent properties, highly conductive properties, and/or other opto-electronic properties.

Evaluation of transition metal oxide as carrier-selective contacts for silicon heterojunction solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ding, L.; Boccard, Matthieu; Holman, Zachary

2015-04-06

"Reducing light absorption in the non-active solar cell layers, while enabling the extraction of the photogenerated minority carriers at quasi-Fermi levels are two key factors to improve current generation and voltage, and therefore efficiency of silicon heterojunction solar devices. To address these two critical aspects, transition metal oxide materials have been proposed as alternative to the n- and p-type amorphous silicon used as electron and hole selective contacts, respectively. Indeed, transition metal oxides such as molybdenum oxide, titanium oxide, nickel oxide or tungsten oxide combine a wide band gap typically over 3 eV with a band structure and theoretical bandmore » alignment with silicon that results in high transparency to the solar spectrum and in selectivity for the transport of only one carrier type. Improving carrier extraction or injection using transition metal oxide has been a topic of investigation in the field of organic solar cells and organic LEDs; from these pioneering works a lot of knowledge has been gained on materials properties, ways to control these during synthesis and deposition, and their impact on device performance. Recently, the transfer of some of this knowledge to silicon solar cells and the successful application of some metal oxide to contact heterojunction devices have gained much attention. In this contribution, we investigate the suitability of various transition metal oxide films (molybdenum oxide, titanium oxide, and tungsten oxide) deposited either by thermal evaporation or sputtering as transparent hole or electron selective transport layer for silicon solar cells. In addition to systematically characterize their optical and structural properties, we use photoemission spectroscopy to relate compound stoichiometry to band structure and characterize band alignment to silicon. The direct silicon/metal oxide interface is further analyzed by quasi-steady state photoconductance decay method to assess the quality of

Method for continuous synthesis of metal oxide powders

DOEpatents

Berry, David A.; Haynes, Daniel J.; Shekhawat, Dushyant; Smith, Mark W.

2015-09-08

A method for the rapid and continuous production of crystalline mixed-metal oxides from a precursor solution comprised of a polymerizing agent, chelated metal ions, and a solvent. The method discharges solution droplets of less than 500 .mu.m diameter using an atomizing or spray-type process into a reactor having multiple temperature zones. Rapid evaporation occurs in a first zone, followed by mixed-metal organic foam formation in a second zone, followed by amorphous and partially crystalline oxide precursor formation in a third zone, followed by formation of the substantially crystalline mixed-metal oxide in a fourth zone. The method operates in a continuous rather than batch manner and the use of small droplets as the starting material for the temperature-based process allows relatively high temperature processing. In a particular embodiment, the first zone operates at 100-300.degree. C., the second zone operates at 300-700.degree. C., and the third operates at 700-1000.degree. C., and fourth zone operates at at least 700.degree. C. The resulting crystalline mixed-metal oxides display a high degree of crystallinity and sphericity with typical diameters on the order of 50 .mu.m or less.

Field-assisted nanopatterning of metals, metal oxides and metal salts

NASA Astrophysics Data System (ADS)

Liu, Jun-Fu; Miller, Glen P.

2009-02-01

The tip-based nanofabrication method called field-assisted nanopatterning or FAN has now been extended to the transfer of metals, metal oxides and metal salts onto various receiving substrates including highly ordered pyrolytic graphite, passivated gold and indium-tin oxide. Standard atomic force microscope tips were first dip-coated using suspensions of inorganic compounds in solvent. The films prepared in this manner were non-uniform and contained inorganic nanoparticles. Tip-based nanopatterning on chosen substrates was conducted under high electric field conditions. The same tip was used for both nanofabrication and imaging. Arbitrary patterns were formed with dimensions that ranged from tens of microns to sub-20 nm and were controlled by tuning the tip bias during fabrication. Most tip-based nanopatterning techniques are limited in terms of the type of species that can be deposited and the type of substrates onto which the deposition occurs. With the successful deposition of inorganic species reported here, FAN is demonstrated to be a truly versatile tip-based nanofabrication technique that is useful for the deposition of a wide variety of both organic and inorganic species including small molecules, large molecules and polymers.

Semiconducting transition metal oxides.

PubMed

Lany, Stephan

2015-07-22

Open shell transition metal oxides are usually described as Mott or charge transfer insulators, which are often viewed as being disparate from semiconductors. Based on the premise that the presence of a correlated gap and semiconductivity are not mutually exclusive, this work reviews electronic structure calculations on the binary 3d oxides, so to distill trends and design principles for semiconducting transition metal oxides. This class of materials possesses the potential for discovery, design, and development of novel functional semiconducting compounds, e.g. for energy applications. In order to place the 3d orbitals and the sp bands into an integrated picture, band structure calculations should treat both contributions on the same footing and, at the same time, account fully for electron correlation in the 3d shell. Fundamentally, this is a rather daunting task for electronic structure calculations, but quasi-particle energy calculations in GW approximation offer a viable approach for band structure predictions in these materials. Compared to conventional semiconductors, the inherent multivalent nature of transition metal cations is more likely to cause undesirable localization of electron or hole carriers. Therefore, a quantitative prediction of the carrier self-trapping energy is essential for the assessing the semiconducting properties and to determine whether the transport mechanism is a band-like large-polaron conduction or a small-polaron hopping conduction. An overview is given for the binary 3d oxides on how the hybridization between the 3d crystal field symmetries with the O-p orbitals of the ligands affects the effective masses and the likelihood of electron and hole self-trapping, identifying those situations where small masses and band-like conduction are more likely to be expected. The review concludes with an illustration of the implications of the increased electronic complexity of transition metal cations on the defect physics and doping, using

Mesoporous carbon incorporated metal oxide nanomaterials as supercapacitor electrodes.

PubMed

Jiang, Hao; Ma, Jan; Li, Chunzhong

2012-08-08

Supercapacitors have attracted huge attention in recent years as they have the potential to satisfy the demand of both huge energy and power density in many advanced technologies. However, poor conductivity and cycling stability remains to be the major challenge for its widespread application. Various strategies have been developed for meeting the ever-increasing energy and power demands in supercapacitors. This Research News article aims to review recent progress in the development of mesoporous carbon incorporated metal oxide nanomaterials, especially metal oxide nanoparticles confined in ordered mesoporous carbon and 1D metal oxides coated with a layer of mesoporous carbon for high-performance supercapacitor applications. In addition, a recent trend in supercapacitor development - hierarchical porous graphitic carbons (HPGC) combining macroporous cores, mesoporous walls, and micropores as an excellent support for metal oxides - is also discussed.

Bioaccessibility of micron-sized powder particles of molybdenum metal, iron metal, molybdenum oxides and ferromolybdenum--Importance of surface oxides.

PubMed

Mörsdorf, Alexander; Odnevall Wallinder, Inger; Hedberg, Yolanda

2015-08-01

The European chemical framework REACH requires that hazards and risks posed by chemicals, including alloys and metals, that are manufactured, imported or used in different products (substances or articles) are identified and proven safe for humans and the environment. Metals and alloys need hence to be investigated on their extent of released metals (bioaccessibility) in biologically relevant environments. Read-across from available studies may be used for similar materials. This study investigates the release of molybdenum and iron from powder particles of molybdenum metal (Mo), a ferromolybdenum alloy (FeMo), an iron metal powder (Fe), MoO2, and MoO3 in different synthetic body fluids of pH ranging from 1.5 to 7.4 and of different composition. Spectroscopic tools and cyclic voltammetry have been employed to characterize surface oxides, microscopy, light scattering and nitrogen absorption for particle characterization, and atomic absorption spectroscopy to quantify released amounts of metals. The release of molybdenum from the Mo powder generally increased with pH and was influenced by the fluid composition. The mixed iron and molybdenum surface oxide of the FeMo powder acted as a barrier both at acidic and weakly alkaline conditions. These findings underline the importance of the surface oxide characteristics for the bioaccessibility of metal alloys. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

The permeability of endplate channels to monovalent and divalent metal cations

PubMed Central

1980-01-01

The relative permeability of endplate channels to monovalent and divalent metal ions was determined from reversal potentials. Thallium is the most permeant ion with a permeability ratio relative to Na+ of 2.5. The selectivity among alkali metals is weak with a sequence, Cs+ greater than Rb+ greater than K+ greater than Na+ greater than Li+, and permeability ratios of 1.4, 1.3, 1.1, 1.0, and 0.9. The selectivity among divalent ions is also weak, with a sequence for alkaline earths of Mg++ greater than Ca++ greater than Ba++ greater than Sr++. The transition metal ions Mn++, Co++, Ni++, Zn++, and Cd++ are also permeant. Permeability ratios for divalent ions decreased as the concentration of divalent ion was increased in a manner consistent with the negative surface potential theory of Lewis (1979 J. Physiol. (Lond.). 286: 417--445). With 20 mM XCl2 and 85.5 mM glucosamine.HCl in the external solution, the apparent permeability ratios for the alkaline earth cations (X++) are in the range 0.18--0.25. Alkali metal ions see the endplate channel as a water-filled, neutral pore without high-field-strength sites inside. Their permeability sequence is the same as their aqueous mobility sequence. Divalent ions, however, have a permeability sequence almost opposite from their mobility sequence and must experience some interaction with groups in the channel. In addition, the concentrations of monovalent and divalent ions are increased near the channel mouth by a weak negative surface potential. PMID:6247423

Dynamical coupled-channels study of {pi}N{yields}{pi}{pi}N reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kamano, H.; Julia-Diaz, B.; Department d'Estructura i Constituents de la Materia and Institut de Ciencies del Cosmos, Universitat de Barcelona E-08028 Barcelona

As a step toward performing a complete coupled-channels analysis of the world data of {pi}N,{gamma}*N{yields}{pi}N,{eta}N,{pi}{pi}N reactions, the {pi}N{yields}{pi}{pi}N reactions are investigated starting with the dynamical coupled-channels model developed in Phys. Rev. C 76, 065201 (2007). The channels included are {pi}N,{eta}N, and {pi}{pi}N which has {pi}{delta},{rho}N, and {sigma}N resonant components. The nonresonant amplitudes are generated from solving a set of coupled-channels equations with the meson-baryon potentials defined by effective Lagrangians. The resonant amplitudes are generated from 16 bare excited nucleon (N*) states that are dressed by the nonresonant interactions as constrained by the unitarity condition. The data of total cross sectionsmore » and {pi}N and {pi}{pi} invariant mass distributions of {pi}{sup +}p{yields}{pi}{sup +}{pi}{sup +}n,{pi}{sup +}{pi}{sup 0}p and {pi}{sup -}p{yields}{pi}{sup +}{pi}{sup -}n,{pi}{sup -}{pi}{sup 0}p,{pi}{sup 0}{pi}{sup 0}n reactions from threshold to the invariant mass W=2 GeV can be described to a very large extent. We show the importance of the coupled-channels effects and the strong interference among the contributions from the {pi}{delta},{sigma}N, and {rho}N channels. The large interference between the resonant and nonresonant amplitudes is also demonstrated. Possible future developments are discussed.« less

Spin-on metal oxide materials with high etch selectivity and wet strippability

NASA Astrophysics Data System (ADS)

Yao, Huirong; Mullen, Salem; Wolfer, Elizabeth; McKenzie, Douglas; Rahman, Dalil; Cho, JoonYeon; Padmanaban, Munirathna; Petermann, Claire; Hong, SungEun; Her, YoungJun

2016-03-01

Metal oxide or metal nitride films are used as hard mask materials in semiconductor industry for patterning purposes due to their excellent etch resistances against the plasma etches. Chemical vapor deposition (CVD) or atomic layer deposition (ALD) techniques are usually used to deposit the metal containing materials on substrates or underlying films, which uses specialized equipment and can lead to high cost-of-ownership and low throughput. We have reported novel spin-on coatings that provide simple and cost effective method to generate metal oxide films possessing good etch selectivity and can be removed by chemical agents. In this paper, new spin-on Al oxide and Zr oxide hard mask formulations are reported. The new metal oxide formulations provide higher metal content compared to previously reported material of specific metal oxides under similar processing conditions. These metal oxide films demonstrate ultra-high etch selectivity and good pattern transfer capability. The cured films can be removed by various chemical agents such as developer, solvents or wet etchants/strippers commonly used in the fab environment. With high metal MHM material as an underlayer, the pattern transfer process is simplified by reducing the number of layers in the stack and the size of the nano structure is minimized by replacement of a thicker film ACL. Therefore, these novel AZ® spinon metal oxide hard mask materials can potentially be used to replace any CVD or ALD metal, metal oxide, metal nitride or spin-on silicon-containing hard mask films in 193 nm or EUV process.

Metal-Free Oxidation of Primary Amines to Nitriles through Coupled Catalytic Cycles.

PubMed

Lambert, Kyle M; Bobbitt, James M; Eldirany, Sherif A; Kissane, Liam E; Sheridan, Rose K; Stempel, Zachary D; Sternberg, Francis H; Bailey, William F

2016-04-04

Synergism among several intertwined catalytic cycles allows for selective, room temperature oxidation of primary amines to the corresponding nitriles in 85-98% isolated yield. This metal-free, scalable, operationally simple method employs a catalytic quantity of 4-acetamido-TEMPO (ACT; TEMPO=2,2,6,6-tetramethylpiperidine N-oxide) radical and the inexpensive, environmentally benign triple salt oxone as the terminal oxidant under mild conditions. Simple filtration of the reaction mixture through silica gel affords pure nitrile products. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Metal oxide-encapsulated dye-sensitized photoanodes for dye-sensitized solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hupp, Joseph T.; Son, Ho-Jin

2016-01-12

Dye-sensitized semiconducting metal oxide films for photoanodes, photoanodes incorporating the films and DSCs incorporating the photoanodes are provided. Also provided are methods for making the dye sensitized semiconducting metal oxide films. The methods of making the films are based on the deposition of an encapsulating layer of a semiconducting metal oxide around the molecular anchoring groups of photosensitizing dye molecules adsorbed to a porous film of the semiconducting metal oxide. The encapsulating layer of semiconducting metal oxide is formed in such a way that it is not coated over the chromophores of the adsorbed dye molecules and, therefore, allows themore » dye molecules to remain electrochemically addressable.« less

Anaerobic Nitrate-Dependent Metal Bio-Oxidation

NASA Astrophysics Data System (ADS)

Weber, K.; Knox, T.; Achenbach, L. A.; Coates, J. D.

2007-12-01

Direct biological oxidation of reduced metals (Fe(II) and U(IV)) coupled to nitrate reduction at circumneutral pH under anaerobic conditions has been recognized in several environments as well as pure culture. Several phylogentically diverse mesophilic bacteria have been described as capable of anaerobic, nitrate-dependent Fe(II) oxidation (NFOx). Our recent identification of a freshwater mesophilic, lithoautotroph, Ferrutens nitratireducens strain 2002, capable of growth through NFOx presents an opportunity to further study metal bio- oxidation. Continuing physiological studies revealed that in addition to Fe(II) oxidation, strain 2002 is capable of oxidizing U(IV) (4 μM) in washed cell suspensions with nitrate serving as the electron acceptor. Pasteurized cultures exhibited abiotic oxidation of 2 μM U(IV). Under growth conditions, strain 2002 catalyzed the oxidation of 12 μM U(IV) within a two week period. Cultures amended with sodium azide, an electron transport inhibitor, demonstrated limited oxidation (7 μM) similar to pasteurized cultures, supporting the direct role of electron transport in U(IV) bio-oxidation. The oxidation of U(IV) coupled denitrification at circumneutral pH would yield enough energy to support anaerobic microbial growth (ΔG°'= -460.36 kJ/mole). It is currently unknown whether or not strain 2002 can couple this metabolism to growth. The growth of F. nitratireducens strain 2002 utilizing Fe(II) as the sole electron donor was previously demonstrated. The amount of U(IV) (~12 μM) that strain 2002 oxidized under similar autotrophic growth conditions yields 0.0019 kJ, enough energy for the generation of ATP (5.3 x 10-20 kJ ATP-1), but not enough energy for cell replication as calculated for nitrate-dependent Fe(II) oxidizing conditions (0.096 kJ) assuming a similar metabolism. In addition to F. nitratireducens strain 2002, a nitrate-dependent Fe(II) oxidizing bacterium isolated from U contaminated groundwater, Diaphorobacter sp. strain

Plasmonically sensitized metal-oxide electron extraction layers for organic solar cells

PubMed Central

Trost, S.; Becker, T.; Zilberberg, K.; Behrendt, A.; Polywka, A.; Heiderhoff, R.; Görrn, P.; Riedl, T.

2015-01-01

ZnO and TiOx are commonly used as electron extraction layers (EELs) in organic solar cells (OSCs). A general phenomenon of OSCs incorporating these metal-oxides is the requirement to illuminate the devices with UV light in order to improve device characteristics. This may cause severe problems if UV to VIS down-conversion is applied or if the UV spectral range (λ < 400 nm) is blocked to achieve an improved device lifetime. In this work, silver nanoparticles (AgNP) are used to plasmonically sensitize metal-oxide based EELs in the vicinity (1–20 nm) of the metal-oxide/organic interface. We evidence that plasmonically sensitized metal-oxide layers facilitate electron extraction and afford well-behaved highly efficient OSCs, even without the typical requirement of UV exposure. It is shown that in the plasmonically sensitized metal-oxides the illumination with visible light lowers the WF due to desorption of previously ionosorbed oxygen, in analogy to the process found in neat metal oxides upon UV exposure, only. As underlying mechanism the transfer of hot holes from the metal to the oxide upon illumination with hν < Eg is verified. The general applicability of this concept to most common metal-oxides (e.g. TiOx and ZnO) in combination with different photoactive organic materials is demonstrated. PMID:25592174

Solvent/oxidant-switchable synthesis of multisubstituted quinazolines and benzimidazoles via metal-free selective oxidative annulation of arylamidines.

PubMed

Lin, Jian-Ping; Zhang, Feng-Hua; Long, Ya-Qiu

2014-06-06

A fast and simple divergent synthesis of multisubstituted quinazolines and benzimidazoles was developed from readily available amidines, via iodine(III)-promoted oxidative C(sp(3))-C(sp(2)) and C(sp(2))-N bond formation in nonpolar and polar solvents, respectively. Further selective synthesis of quinazolines in polar solvent was realized by TEMPO-catalyzed sp(3)C-H/sp(2)C-H direct coupling of the amidine with K2S2O8 as the oxidant. No metal, base, or other additives were needed.

Metal-organic framework derived hollow polyhedron metal oxide posited graphene oxide for energy storage applications.

PubMed

Ramaraju, Bendi; Li, Cheng-Hung; Prakash, Sengodu; Chen, Chia-Chun

2016-01-18

A composite made from hollow polyhedron copper oxide and graphene oxide was synthesized by sintering a Cu-based metal-organic framework (Cu-MOF) embedded with exfoliated graphene oxide. As a proof-of-concept application, the obtained Cu(ox)-rGO materials were used in a lithium-ion battery and a sodium-ion battery as anode materials. Overall, the Cu(ox)-rGO composite delivers excellent electrochemical properties with stable cycling when compared to pure CuO-rGO and Cu-MOF.

Coupling catalytic hydrolysis and oxidation of HCN over HZSM-5 modified by metal (Fe,Cu) oxides

NASA Astrophysics Data System (ADS)

Hu, Yanan; Liu, Jiangping; Cheng, Jinhuan; Wang, Langlang; Tao, Lei; Wang, Qi; Wang, Xueqian; Ning, Ping

2018-01-01

In this work, a series of metal oxides (Fe,Cu) modified HZSM-5 catalysts were synthesized by incipient-wetness impregnation method and then characterized by XRD, N2 adsorption-desorption, H2-TPR, NH3-TPD, UV-vis, FT-IR and XPS measurements. The catalytic hydrolysis and oxidation behaviors toward HCN were investigated. The results indicated that the Fe-Cu/HZSM-5 catalysts exhibited more excellent performence on coupling catalytic hydrolysis and oxidation of HCN than HZSM-5, Fe/HZSM-5, Cu/HZSM-5, and both nearly 100% HCN conversion and 80% N2 selectivity were obtained at about 250 °C. The improved catalytic performance could be ascribed to the creation of highly dispersed iron and copper composites on the surface of the HZSM-5 support, the excellent redox and regulated acid properties of the active ingredients. Moreover, the highly N2 selectivity could be attributed to the good interaction between the Fe and Cu nanocomposites which was facilitated to the NH3-SCR (selective catalytic reduction of NO by NH3) reaction.

Improvement of hot-carrier and radiation hardnesses in metal-oxide-nitride-oxide semiconductor devices by irradiation-then-anneal treatments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang-Liao, K.S.; Hwu, J.G.

The hardnesses of hot-carrier and radiation of metal-oxide nitride-oxide semiconductor (MONOS) devices can be improved by the irradiation-then-anneal (ITA) treatments. Each treatment includes an irradiation of Co-60 with a total dose of 1M rads(SiO[sub 2]) and an anneal in N[sub 2] at 400 C for 10 min successively. This improvement can be explained by the release of SiO[sub 2]/Si interfacial strain.

Method and apparatus for the production of metal oxide powder

DOEpatents

Harris, Michael T.; Scott, Timothy C.; Byers, Charles H.

1993-01-01

The present invention provides a method for preparing metal oxide powder. A first solution, which is substantially organic, is prepared. A second solution, which is an aqueous solution substantially immiscible in the first solution, is prepared and delivered as drops to the first solution. The drops of the second solution are atomized by a pulsed electric field forming micro-drops of the second solution. Reagents in the first solution diffuse into and react with reactants in the micro-drops of the second solution forming metal hydroxide or oxalate particles. The metal hydroxide or metal oxalate particles are then recovered and dried to produce the metal oxide powder. An apparatus for preparing a metal oxide powder is also disclosed.

Method and apparatus for the production of metal oxide powder

DOEpatents

Harris, Michael T.; Scott, Timothy C.; Byers, Charles H.

1992-01-01

The present invention provides a method for preparing metal oxide powder. A first solution, which is substantially organic, is prepared. A second solution, which is an aqueous solution substantially immiscible in the first solution, is prepared and delivered as drops to the first solution. The drops of the second solution are atomized by a pulsed electric field forming micro-drops of the second solution. Reagents in the first solution diffuse into and react with reactants in the micro-drops of the second solution forming metal hydroxide or oxalate particles. The metal hydroxide or metal oxalate particles are then recovered and dried to produce the metal oxide powder. An apparatus for preparing a metal oxide powder is also disclosed.

Cytotoxicity, permeability, and inflammation of metal oxide nanoparticles in human cardiac microvascular endothelial cells: cytotoxicity, permeability, and inflammation of metal oxide nanoparticles.

PubMed

Sun, Jing; Wang, Shaochuang; Zhao, Dong; Hun, Fei Han; Weng, Lei; Liu, Hui

2011-10-01

Wide applications and extreme potential of metal oxide nanoparticles (NPs) increase occupational and public exposure and may yield extraordinary hazards for human health. Exposure to NPs has a risk for dysfunction of the vascular endothelial cells. The objective of this study was to assess the cytotoxicity of six metal oxide NPs to human cardiac microvascular endothelial cells (HCMECs) in vitro. Metal oxide NPs used in this study included zinc oxide (ZnO), iron(III) oxide (Fe(2)O(3)), iron(II,III) oxide (Fe(3)O(4)), magnesium oxide (MgO), aluminum oxide (Al(2)O(3)), and copper(II) oxide (CuO). The cell viability, membrane leakage of lactate dehydrogenase, intracellular reactive oxygen species, permeability of plasma membrane, and expression of inflammatory markers vascular cell adhesion molecule-1, intercellular adhesion molecule-1, macrophage cationic peptide-1, and interleukin-8 in HCMECs were assessed under controlled and exposed conditions (12-24 h and 0.001-100 μg/ml of exposure). The results indicated that Fe(2)O(3), Fe(3)O(4), and Al(2)O(3) NPs did not have significant effects on cytotoxicity, permeability, and inflammation response in HCMECs at any of the concentrations tested. ZnO, CuO, and MgO NPs produced the cytotoxicity at the concentration-dependent and time-dependent manner, and elicited the permeability and inflammation response in HCMECs. These results demonstrated that cytotoxicity, permeability, and inflammation in vascular endothelial cells following exposure to metal oxide nanoparticles depended on particle composition, concentration, and exposure time. © Springer Science+Business Media B.V. 2011

Multiscale model of metal alloy oxidation at grain boundaries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sushko, Maria L., E-mail: maria.sushko@pnnl.gov; Alexandrov, Vitaly; Schreiber, Daniel K.

2015-06-07

High temperature intergranular oxidation and corrosion of metal alloys is one of the primary causes of materials degradation in nuclear systems. In order to gain insights into grain boundary oxidation processes, a mesoscale metal alloy oxidation model is established by combining quantum Density Functional Theory (DFT) and mesoscopic Poisson-Nernst-Planck/classical DFT with predictions focused on Ni alloyed with either Cr or Al. Analysis of species and fluxes at steady-state conditions indicates that the oxidation process involves vacancy-mediated transport of Ni and the minor alloying element to the oxidation front and the formation of stable metal oxides. The simulations further demonstrate thatmore » the mechanism of oxidation for Ni-5Cr and Ni-4Al is qualitatively different. Intergranular oxidation of Ni-5Cr involves the selective oxidation of the minor element and not matrix Ni, due to slower diffusion of Ni relative to Cr in the alloy and due to the significantly smaller energy gain upon the formation of nickel oxide compared to that of Cr{sub 2}O{sub 3}. This essentially one-component oxidation process results in continuous oxide formation and a monotonic Cr vacancy distribution ahead of the oxidation front, peaking at alloy/oxide interface. In contrast, Ni and Al are both oxidized in Ni-4Al forming a mixed spinel NiAl{sub 2}O{sub 4}. Different diffusivities of Ni and Al give rise to a complex elemental distribution in the vicinity of the oxidation front. Slower diffusing Ni accumulates in the oxide and metal within 3 nm of the interface, while Al penetrates deeper into the oxide phase. Ni and Al are both depleted from the region 3–10 nm ahead of the oxidation front creating voids. The oxide microstructure is also different. Cr{sub 2}O{sub 3} has a plate-like structure with 1.2–1.7 nm wide pores running along the grain boundary, while NiAl{sub 2}O{sub 4} has 1.5 nm wide pores in the direction parallel to the grain boundary and 0.6 nm pores in the

Well-Known Mediators of Selective Oxidation with Unknown Electronic Structure: Metal-Free Generation and EPR Study of Imide-N-oxyl Radicals.

PubMed

Krylov, Igor B; Kompanets, Mykhailo O; Novikova, Katerina V; Opeida, Iosip O; Kushch, Olga V; Shelimov, Boris N; Nikishin, Gennady I; Levitsky, Dmitri O; Terent'ev, Alexander O

2016-01-14

Nitroxyl radicals are widely used in chemistry, materials sciences, and biology. Imide-N-oxyl radicals are subclass of unique nitroxyl radicals that proved to be useful catalysts and mediators of selective oxidation and CH-functionalization. An efficient metal-free method was developed for the generation of imide-N-oxyl radicals from N-hydroxyimides at room temperature by the reaction with (diacetoxyiodo)benzene. The method allows for the production of high concentrations of free radicals and provides high resolution of their EPR spectra exhibiting the superhyperfine structure from benzene ring protons distant from the radical center. An analysis of the spectra shows that, regardless of the electronic effects of the substituents in the benzene ring, the superhyperfine coupling constant of an unpaired electron with the distant protons at positions 4 and 5 of the aromatic system is substantially greater than that with the protons at positions 3 and 6 that are closer to the N-oxyl radical center. This is indicative of an unusual character of the spin density distribution of the unpaired electron in substituted phthalimide-N-oxyl radicals. Understanding of the nature of the electron density distribution in imide-N-oxyl radicals may be useful for the development of commercial mediators of oxidation based on N-hydroxyimides.

Growth and sacrificial oxidation of transition metal nanolayers

NASA Astrophysics Data System (ADS)

Tsarfati, Tim; Zoethout, Erwin; van de Kruijs, Robbert; Bijkerk, Fred

2009-04-01

Growth and oxidation of Au, Pt, Pd, Rh, Cu, Ru, Ni and Co layers of 0.3-4.3 nm thickness on Mo have been investigated with ARPES and AFM. Co and Ni layers oxidize while the Mo remains metallic. For nobler metals, the on top O and oxidation state of subsurface Mo increase, suggesting sacrificial e - donation by Mo. Au and Cu, in spite of their significantly lower surface free energy, grow in islands on Mo and actually promote Mo oxidation. Applications of the sacrificial oxidation in nanometer thin layers exist in a range of nanoscopic devices, such as nano-electronics and protection of e.g. multilayer X-ray optics for astronomy, medicine and lithography.

Process for Making a Noble Metal on Tin Oxide Catalyst

NASA Technical Reports Server (NTRS)

Davis, Patricia; Miller, Irvin; Upchurch, Billy

2010-01-01

To produce a noble metal-on-metal oxide catalyst on an inert, high-surface-area support material (that functions as a catalyst at approximately room temperature using chloride-free reagents), for use in a carbon dioxide laser, requires two steps: First, a commercially available, inert, high-surface-area support material (silica spheres) is coated with a thin layer of metal oxide, a monolayer equivalent. Very beneficial results have been obtained using nitric acid as an oxidizing agent because it leaves no residue. It is also helpful if the spheres are first deaerated by boiling in water to allow the entire surface to be coated. A metal, such as tin, is then dissolved in the oxidizing agent/support material mixture to yield, in the case of tin, metastannic acid. Although tin has proven especially beneficial for use in a closed-cycle CO2 laser, in general any metal with two valence states, such as most transition metals and antimony, may be used. The metastannic acid will be adsorbed onto the high-surface-area spheres, coating them. Any excess oxidizing agent is then evaporated, and the resulting metastannic acid-coated spheres are dried and calcined, whereby the metastannic acid becomes tin(IV) oxide. The second step is accomplished by preparing an aqueous mixture of the tin(IV) oxide-coated spheres, and a soluble, chloride-free salt of at least one catalyst metal. The catalyst metal may be selected from the group consisting of platinum, palladium, ruthenium, gold, and rhodium, or other platinum group metals. Extremely beneficial results have been obtained using chloride-free salts of platinum, palladium, or a combination thereof, such as tetraammineplatinum (II) hydroxide ([Pt(NH3)4] (OH)2), or tetraammine palladium nitrate ([Pd(NH3)4](NO3)2).

Metal sulfide initiators for metal oxide sorbent regeneration

DOEpatents

Turk, Brian S.; Gupta, Raghubir P.

2001-01-01

A process of regenerating a sulfided sorbent is provided. According to the process of the invention, a substantial portion of the energy necessary to initiate the regeneration reaction is provided by the combustion of a particulate metal sulfide additive. In using the particulate metal sulfide additive, the oxygen-containing gas used to regenerate the sulfided sorbent can be fed to the regeneration zone without heating or at a lower temperature than used in conventional processes wherein the regeneration reaction is initiated only by heating the oxygen-containing gas. The particulate metal sulfide additive is preferably an inexpensive mineral ore such as iron pyrite which does not adversely affect the regeneration or corresponding desulfurization reactions. The invention further includes a sorbent composition comprising the particulate metal sulfide additive in admixture with an active metal oxide sorbent capable of removing one or more sulfur compounds from a sulfur-containing gas stream.

Metal sulfide initiators for metal oxide sorbent regeneration

DOEpatents

Turk, Brian S.; Gupta, Raghubir P.

1999-01-01

A process of regenerating a sulfided sorbent is provided. According to the process of the invention, a substantial portion of the energy necessary to initiate the regeneration reaction is provided by the combustion of a particulate metal sulfide additive. In using the particulate metal sulfide additive, the oxygen-containing gas used to regenerate the sulfided sorbent can be fed to the regeneration zone without heating or at a lower temperature than used in conventional processes wherein the regeneration reaction is initiated only by heating the oxygen-containing. The particulate metal sulfide additive is preferably an inexpensive mineral ore such as iron pyrite which does not adversely affect the regeneration or corresponding desulfurization reactions. The invention further includes a sorbent composition comprising the particulate metal sulfide additive in admixture with an active metal oxide sorbent capable of removing one or more sulfur compounds from a sulfur-containing gas stream.

Metal sulfide initiators for metal oxide sorbent regeneration

DOEpatents

Turk, B.S.; Gupta, R.P.

1999-06-22

A process of regenerating a sulfided sorbent is provided. According to the process of the invention, a substantial portion of the energy necessary to initiate the regeneration reaction is provided by the combustion of a particulate metal sulfide additive. In using the particulate metal sulfide additive, the oxygen-containing gas used to regenerate the sulfided sorbent can be fed to the regeneration zone without heating or at a lower temperature than used in conventional processes wherein the regeneration reaction is initiated only by heating the oxygen-containing gas. The particulate metal sulfide additive is preferably an inexpensive mineral ore such as iron pyrite which does not adversely affect the regeneration or corresponding desulfurization reactions. The invention further includes a sorbent composition comprising the particulate metal sulfide additive in admixture with an active metal oxide sorbent capable of removing one or more sulfur compounds from a sulfur-containing gas stream. 1 fig.

Regularities of Filamentary Channels Formation During Formation of Nanostructured Non-Metallic Inorganic Coatings in Microplasma Galvanostatic Mode in Solutions

NASA Astrophysics Data System (ADS)

Mamaev, A. I.; Mamaeva, V. A.; Kolenchin, N. F.; Chubenko, A. K.; Kovalskaya, Ya. B.; Konstantinova, T. A.; Dolgova, Yu. N.; Beletskaya, E. Yu.

2016-04-01

This paper presents the theoretical models describing the growth of filamentary channels of nanostructured non-metallic coatings formed by anodizing and microplasma oxidation. The authors identified dependences of the number of pores on the coating thickness. The paper presents graphic dependences of the number of filamentary channels on the process time and the coating thickness. These dependences allow calculating through and surface porosity, and in cases, when the pores are filled with functional material, they allow calculating the concentration distribution of this functional material throughout the coating thickness. The theoretical models enhance our understanding of the nature of anode processes and can be used to describe and forecast the growth and filling of porous coatings, so they can also be used to create functional and bioactive materials.

Multilevel metallization method for fabricating a metal oxide semiconductor device

NASA Technical Reports Server (NTRS)

Hollis, B. R., Jr.; Feltner, W. R.; Bouldin, D. L.; Routh, D. E. (Inventor)

1978-01-01

An improved method is described of constructing a metal oxide semiconductor device having multiple layers of metal deposited by dc magnetron sputtering at low dc voltages and low substrate temperatures. The method provides multilevel interconnections and cross over between individual circuit elements in integrated circuits without significantly reducing the reliability or seriously affecting the yield.

A Comprehensive Review of Glucose Biosensors Based on Nanostructured Metal-Oxides

PubMed Central

Rahman, Md. Mahbubur; Saleh Ahammad, A. J.; Jin, Joon-Hyung; Ahn, Sang Jung; Lee, Jae-Joon

2010-01-01

Nanotechnology has opened new and exhilarating opportunities for exploring glucose biosensing applications of the newly prepared nanostructured materials. Nanostructured metal-oxides have been extensively explored to develop biosensors with high sensitivity, fast response times, and stability for the determination of glucose by electrochemical oxidation. This article concentrates mainly on the development of different nanostructured metal-oxide [such as ZnO, Cu(I)/(II) oxides, MnO2, TiO2, CeO2, SiO2, ZrO2, and other metal-oxides] based glucose biosensors. Additionally, we devote our attention to the operating principles (i.e., potentiometric, amperometric, impedimetric and conductometric) of these nanostructured metal-oxide based glucose sensors. Finally, this review concludes with a personal prospective and some challenges of these nanoscaled sensors. PMID:22399911

Dissolution of Fe(III) (hydr) oxides by metal-EDTA complexes

NASA Astrophysics Data System (ADS)

Ngwack, Bernd; Sigg, Laura

1997-03-01

The dissolution of Fe(III)(hydr)oxides (goethite and hydrous ferric oxide) by metal-EDTA complexes occurs by ligand-promoted dissolution. The process is initiated by the adsorption of metal-EDTA complexes to the surface and is followed by the dissociation of the complex at the surface and the release of Fe(III)EDTA into solution. The dissolution rate is decreased to a great extent if EDTA is complexed by metals in comparison to the uncomplexed EDTA. The rate decreases in the order EDTA CaEDTA ≫ PbEDTA > ZnEDTA > CuEDTA > Co(II)EDTA > NiEDTA. Two different rate-limiting steps determine the dissolution process: (1) detachment of Fe(III) from the oxide-structure and (2) dissociation of the metal-EDTA complexes. In the case of goethite, step 1 is slower than step 2 and the dissolution rates by various metals are similar. In the case of hydrous ferric oxide, step 2 is rate-limiting and the effect of the complexed metal is very pronounced.

Dual passivation of intrinsic defects at the compound semiconductor/oxide interface using an oxidant and a reductant.

PubMed

Kent, Tyler; Chagarov, Evgeniy; Edmonds, Mary; Droopad, Ravi; Kummel, Andrew C

2015-05-26

Studies have shown that metal oxide semiconductor field-effect transistors fabricated utilizing compound semiconductors as the channel are limited in their electrical performance. This is attributed to imperfections at the semiconductor/oxide interface which cause electronic trap states, resulting in inefficient modulation of the Fermi level. The physical origin of these states is still debated mainly because of the difficulty in assigning a particular electronic state to a specific physical defect. To gain insight into the exact source of the electronic trap states, density functional theory was employed to model the intrinsic physical defects on the InGaAs (2 × 4) surface and to model the effective passivation of these defects by utilizing both an oxidant and a reductant to eliminate metallic bonds and dangling-bond-induced strain at the interface. Scanning tunneling microscopy and spectroscopy were employed to experimentally determine the physical and electronic defects and to verify the effectiveness of dual passivation with an oxidant and a reductant. While subsurface chemisorption of oxidants on compound semiconductor substrates can be detrimental, it has been shown theoretically and experimentally that oxidants are critical to removing metallic defects at oxide/compound semiconductor interfaces present in nanoscale channels, oxides, and other nanostructures.

Fully transparent thin film transistors based on zinc oxide channel layer and molybdenum doped indium oxide electrodes

NASA Astrophysics Data System (ADS)

MÄ dzik, Mateusz; Elamurugu, Elangovan; Viegas, Jaime

2016-03-01

In this work we report the fabrication of thin film transistors (TFT) with zinc oxide channel and molybdenum doped indium oxide (IMO) electrodes, achieved by room temperature sputtering. A set of devices was fabricated, with varying channel width and length from 5μm to 300μm. Output and transfer characteristics were then extracted to study the performance of thin film transistors, namely threshold voltage and saturation current, enabling to determine optimal fabrication process parameters. Optical transmission in the UV-VIS-IR are also reported.

Method and apparatus for the production of metal oxide powder

DOEpatents

Harris, M.T.; Scott, T.C.; Byers, C.H.

1992-06-16

The present invention provides a method for preparing metal oxide powder. A first solution, which is substantially organic, is prepared. A second solution, which is an aqueous solution substantially immiscible in the first solution, is prepared and delivered as drops to the first solution. The drops of the second solution are atomized by a pulsed electric field forming micro-drops of the second solution. Reagents in the first solution diffuse into and react with reactants in the micro-drops of the second solution forming metal hydroxide or oxalate particles. The metal hydroxide or metal oxalate particles are then recovered and dried to produce the metal oxide powder. An apparatus for preparing a metal oxide powder is also disclosed. 2 figs.

Process for making a noble metal on tin oxide catalyst

NASA Technical Reports Server (NTRS)

Upchurch, Billy T. (Inventor); Davis, Patricia (Inventor); Miller, Irvin M. (Inventor)

1989-01-01

A quantity of reagent grade tin metal or compound, chloride-free, and high-surface-area silica spheres are placed in deionized water, followed by deaerating the mixture by boiling and adding an oxidizing agent, such as nitric acid. The nitric acid oxidizes the tin to metastannic acid which coats the spheres because the acid is absorbed on the substrate. The metastannic acid becomes tin oxide upon drying and calcining. The tin-oxide coated silica spheres are then placed in water and boiled. A chloride-free precious metal compound in aqueous solution is then added to the mixture containing the spheres, and the precious metal compound is reduced to a precious metal by use of a suitable reducing agent such as formic acid. Very beneficial results were obtained using the precious metal compound tetraammine platinum(II) hydroxide.

Mesoporous metal oxide microsphere electrode compositions and their methods of making

DOEpatents

Paranthaman, Mariappan Parans; Liu, Hansan; Brown, Gilbert M.; Sun, Xiao-Guang; Bi, Zhonghe

2016-12-06

Compositions and methods of making are provided for mesoporous metal oxide microspheres electrodes. The mesoporous metal oxide microsphere compositions comprise (a) microspheres with an average diameter between 200 nanometers (nm) and 10 micrometers (.mu.m); (b) mesopores on the surface and interior of the microspheres, wherein the mesopores have an average diameter between 1 nm and 50 nm and the microspheres have a surface area between 50 m.sup.2/g and 500 m.sup.2/g. The methods of making comprise forming composite powders. The methods may also comprise refluxing the composite powders in a basic solution to form an etched powder, washing the etched powder with an acid to form a hydrated metal oxide, and heat-treating the hydrated metal oxide to form mesoporous metal oxide microspheres.

Interface states and internal photoemission in p-type GaAs metal-oxide-semiconductor surfaces

NASA Technical Reports Server (NTRS)

Kashkarov, P. K.; Kazior, T. E.; Lagowski, J.; Gatos, H. C.

1983-01-01

An interface photodischarge study of p-type GaAs metal-oxide-semiconductor (MOS) structures revealed the presence of deep interface states and shallow donors and acceptors which were previously observed in n-type GaAs MOS through sub-band-gap photoionization transitions. For higher photon energies, internal photoemission was observed, i.e., injection of electrons to the conduction band of the oxide from either the metal (Au) or from the GaAs valence band; the threshold energies were found to be 3.25 and 3.7 + or - 0.1 eV, respectively. The measured photoemission current exhibited a thermal activation energy of about 0.06 eV, which is consistent with a hopping mechanism of electron transport in the oxide.

Metal-free g-C{sub 3}N{sub 4} photocatalyst by sulfuric acid activation for selective aerobic oxidation of benzyl alcohol under visible light

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Ligang; University of Chinese Academy of Sciences, Beijing 100049; Liu, Di

2014-11-15

Highlights: • A novel visible-light-driven acid-modified g-C{sub 3}N{sub 4} was prepared. • The texture, electronic and surface property were tuned by acid modification. • Acid-modified g-C{sub 3}N{sub 4} shows much higher activity for photocatalytic activity. • Acid sites on the surface of g-C{sub 3}N{sub 4} favor efficient charge separation. - Abstract: In this work, modification of graphitic carbon nitride photocatalyst with acid was accomplished with a facile method through reflux in different acidic substances. The g-C{sub 3}N{sub 4}-based material was found to be a metal-free photocatalyst useful for the selective oxidation of benzyl alcohol with dioxygen as the oxidant undermore » visible light irradiation. Acid modification had a significant influence on the photocatalytic performance of g-C{sub 3}N{sub 4}. Among all acid tested, sulfuric acid-modified g-C{sub 3}N{sub 4} showed the highest catalytic activity and gave benzaldehyde in 23% yield for 4 h under visible light irradiation, which was about 2.5 times higher than that of g-C{sub 3}N{sub 4}. The acid modification effectively improved surface area, reduced structural size, enlarged band gap, enhanced surface chemical state, and facilitated photoinduced charge separation, contributing to the enhanced photocatalytic activity. It is hoped that our work can open promising prospects for the utilization of metal free g-C{sub 3}N{sub 4}-based semiconductor as visible-light photocatalyst for selective organic transformation.« less

Nanostructured carbon-metal oxide composite electrodes for supercapacitors: a review

NASA Astrophysics Data System (ADS)

Zhi, Mingjia; Xiang, Chengcheng; Li, Jiangtian; Li, Ming; Wu, Nianqiang

2012-12-01

This paper presents a review of the research progress in the carbon-metal oxide composites for supercapacitor electrodes. In the past decade, various carbon-metal oxide composite electrodes have been developed by integrating metal oxides into different carbon nanostructures including zero-dimensional carbon nanoparticles, one-dimensional nanostructures (carbon nanotubes and carbon nanofibers), two-dimensional nanosheets (graphene and reduced graphene oxides) as well as three-dimensional porous carbon nano-architectures. This paper has described the constituent, the structure and the properties of the carbon-metal oxide composites. An emphasis is placed on the synergistic effects of the composite on the performance of supercapacitors in terms of specific capacitance, energy density, power density, rate capability and cyclic stability. This paper has also discussed the physico-chemical processes such as charge transport, ion diffusion and redox reactions involved in supercapacitors.