Journal articles: 'Pinnick oxidation'

1

Hussein, Aqeel A., Azzam A. M. Al-Hadedi, Alaa J. Mahrath, Gamal A. I. Moustafa, Faisal A. Almalki, Alaa Alqahtani, Sergey Shityakov, and Moaed E. Algazally. "Mechanistic investigations on Pinnick oxidation: a density functional theory study." Royal Society Open Science 7, no. 2 (February 2020): 191568. http://dx.doi.org/10.1098/rsos.191568.

Full text

Abstract:

A computational study on Pinnick oxidation of aldehydes into carboxylic acids using density functional theory (DFT) calculations has been evaluated with the (SMD)-M06-2X/aug-pVDZ level of theory, leading to an important understanding of the reaction mechanism that agrees with the experimental observations and explaining the substantial role of acid in driving the reaction. The DFT results elucidated that the first reaction step (FRS) proceeds in a manner where chlorous acid reacts with the aldehyde group through a distorted six-membered ring transition state to give a hydroxyallyl chlorite intermediate that undergoes a pericyclic fragmentation to release the carboxylic acid as a second reaction step (SRS). 1 H NMR experiments and simulations showed that hydrogen bonding between carbonyl and t -butanol is unlikely to occur. Additionally, it was found that the FRS is a rate-determining and thermoneutral step, whereas SRS is highly exergonic with a low energetic barrier due to the Cl(III) → Cl(II) reduction. Frontier molecular orbital analysis, intrinsic reaction coordinate, molecular dynamics and distortion/interaction analysis further supported the proposed mechanism.

APA, Harvard, Vancouver, ISO, and other styles

2

Guo, Yanjun, Chenhong Meng, Xueli Liu, Chen Li, Aibao Xia, Zhenyuan Xu, and Danqian Xu. "Successive Waste as Reagent: Two More Steps Forward in a Pinnick Oxidation." Organic Letters 20, no. 4 (February 2, 2018): 913–16. http://dx.doi.org/10.1021/acs.orglett.7b03684.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Rafiee, Mohammad, Zachary M. Konz, Matthew D. Graaf, Hannes F. Koolman, and Shannon S. Stahl. "Electrochemical Oxidation of Alcohols and Aldehydes to Carboxylic Acids Catalyzed by 4-Acetamido-TEMPO: An Alternative to “Anelli” and “Pinnick” Oxidations." ACS Catalysis 8, no. 7 (June 11, 2018): 6738–44. http://dx.doi.org/10.1021/acscatal.8b01640.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Goh, Kien Soon, and Choon-Hong Tan. "Metal-free pinnick-type oxidative amidation of aldehydes." RSC Advances 2, no. 13 (2012): 5536. http://dx.doi.org/10.1039/c2ra20773g.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Liu, Xiao, and Long Mei Wang. "Effect of RE on Cyclic Oxidation Behavior of Ferrite Stainless Steel." Applied Mechanics and Materials 204-208 (October 2012): 4063–66. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.4063.

Full text

Abstract:

A primary study on the resistance to high-temperature-oxidation of 430 ferrite stainless steel and its oxidation process before and after the addition of RE elements was reported. Results show that the oxidation resistance of 430 ferrite stainless steel after adding RE is indeed great. The value of oxidation rate of Sample 1 (without adding RE) is 2.87 times higher than Sample 2, respectively at 1423K after oxidizeing for totally 144h. And the dense and adherent Cr2O3 scale and FeCr2O4 scale are formed and played the protection role to the 430 ferrite stainless steel. In the internal oxidation layer, the pinning effect of silicon dioxide is strengthened by RE.

APA, Harvard, Vancouver, ISO, and other styles

6

Goh, Kien Soon, and Choon-Hong Tan. "ChemInform Abstract: Metal-Free Pinnick-Type Oxidative Amidation of Aldehydes." ChemInform 43, no. 43 (September 27, 2012): no. http://dx.doi.org/10.1002/chin.201243047.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Liu, Xiao, and Long Mei Wang. "Effect of Y on Cyclic Oxidation Behavior of FeCrNi Heat-Resisting Steel." Advanced Materials Research 557-559 (July 2012): 170–74. http://dx.doi.org/10.4028/www.scientific.net/amr.557-559.170.

Full text

Abstract:

The oxidation resistance of FeCrNi heat-resisting steel at 1150°C and 1200°C is analyzed and studied using XRD, SEM and EDS techniques. The results show that the oxidation resistance of the heat-resisting steel is improved remarkably after adding yttrium. The value of oxidation rate of experimental Sample 1 (without adding Y) is 3.25 times and 1.56 times higher than Sample 2, respectively at 1150°C and 1200°C after oxidizeing for totally 144h. On the surface of the heat-resisting steel containing Y, the dense and adherent Cr2O3 scale and FeCr2O4 scale are formed and played the protection role. In the internal oxidation layer, the pinning effect of silicon dioxide is strengthened by Y, and Y has a pining effect directly.

APA, Harvard, Vancouver, ISO, and other styles

8

Su, Yong, Shunke Zhang, Guangyan Fu, Qun Liu, and Yuanze Tang. "High-Temperature Oxidation Behavior of Fe-Si-Ce Alloys." High Temperature Materials and Processes 35, no. 2 (February 1, 2016): 177–83. http://dx.doi.org/10.1515/htmp-2014-0171.

Full text

Abstract:

AbstractThe oxidation behavior of Fe-Si-Ce alloys with different Ce content at 1,173 and 1,273 K has been studied by means of optical microscope (OM), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscope (SEM). Results show that the Ce addition refines the grain size of Fe-Si alloys, and correspondingly the grain size of the oxides decreases, which increases the grain boundary concentration and promotes the short-path diffusion of the alloying elements and oxygen. During oxidation, the positive effect of the grain refinement on the oxidation behavior of the alloy is more obvious than negative effect, so the Ce addition improves the oxidation resistances of the Fe-3Si alloys. Compared to Fe-3Si-0.5Ce alloy, Fe-3Si-5.0Ce alloy has the larger mass gain for the preferential oxidation of the excessive content of Ce exceeding its beneficial effects. The rare earth Ce changes the oxidation mechanism of Fe-Si alloys. Oxygen penetrates the oxide scales and reacts preferentially with Ce-rich phases, which results in the pinning effect and improves the adhesion of the oxide scales.

APA, Harvard, Vancouver, ISO, and other styles

9

Duan, Hang, Yan Liu, Tiesong Lin, Hui Zhang, and Zhengren Huang. "Investigation on the High-Temperature Oxidation Resistance of Ni-(3~10) Ta and Ni-(3~10) Y Alloys." Metals 9, no. 1 (January 17, 2019): 97. http://dx.doi.org/10.3390/met9010097.

Full text

Abstract:

Ni-(3~10) Ta and Ni-(3~10) Y alloys were fabricated by vacuum arc melting. The oxidation resistance of the alloys was studied by cyclic and isothermal oxidation tests at 800 °C in static air. The present work focused on the investigation of the effects of the alloying elements (Ta and Y) on the oxidation behavior of Ni-based alloys. The oxidation behavior of alloys was evaluated by mass gain, composition, as well as the microstructure of oxidized products. The experimental results indicated that Ta at a low content (3 wt %) had a positive role in enhancing oxidation resistance by decreasing the oxygen vacancy concentration of the oxide layer to prevent the inward diffusion of oxygen during oxidation, and the mass gain decreased from 2.9 mg·cm−2 to 1.7 mg·cm−2 (800 °C/200 h), while Y (3~10 wt %) degraded the oxidation resistance. However, it is worth mentioning that the pinning effect of Y2O3 increased the adhesion between the substrate and oxide layer by changing the growing patterns of the oxide layer from a plane growth to fibrous growth. Among the results, the bonding of the substrate and oxide layer was best in the Ni-3Y alloys.

APA, Harvard, Vancouver, ISO, and other styles

10

Berkovits, V. L., V. A. Kiselev, T. A. Minashvili, and V. I. Safarov. "Oxidation states and Fermi-level pinning on GaAs(110) surface." Solid State Communications 65, no. 5 (February 1988): 385–88. http://dx.doi.org/10.1016/0038-1098(88)90722-3.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Bertness, K. A., T. Kendelewicz, R. S. List, M. D. Williams, I. Lindau, and W. E. Spicer. "Fermi level pinning during oxidation of atomically clean n‐InP(110)." Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films 4, no. 3 (May 1986): 1424–26. http://dx.doi.org/10.1116/1.573525.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Saha, Atanu, Sandeep R. Shah, Rishi Raj, and Stephen E. Russek. "Polymer-derived SiCN composites with magnetic properties." Journal of Materials Research 18, no. 11 (November 2003): 2549–51. http://dx.doi.org/10.1557/jmr.2003.0356.

Full text

Abstract:

Composites consisting of particles of α-iron dispersed in silicon carbonitride (SiCN) were fabricated by a polymer route. The composites had iron inclusions with the same magnetization as bulk iron, but they resisted oxidation up to 500°C and had a hardness of 5-7 GPa. The composites behaved as ferromagnets, albeit with a low susceptibility attributed to the pinning of the domains by imperfect interfaces and to the elastic resistance from the SiCN matrix. This low-cost, low-temperature processing method can be used to make different kinds of ceramic composites with multifunctional properties.

APA, Harvard, Vancouver, ISO, and other styles

13

Amato, J. C. "Vortex pinning arrays produced by nano-oxidation using an atomic force microscope." Applied Physics Letters 85, no. 1 (July 5, 2004): 103–5. http://dx.doi.org/10.1063/1.1768300.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Takazaki, Yasuaki, Zhiyong Yang, Masahiro Ebihara, Katsuya Inoue, and Takashi Kawamura. "A Honeycomb Network of a Paddlewheel-type Dirhodium Complex in Two Oxidation States and Pinning of the Oxidation States." Chemistry Letters 32, no. 2 (February 2003): 120–21. http://dx.doi.org/10.1246/cl.2003.120.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Ri, Sung-Gi, Daisuke Takeuchi, Norio Tokuda, Hideyo Okushi, and Satoshi Yamasaki. "Fermi level pinning-free interface at metals/homoepitaxial diamond (111) films after oxidation treatments." Applied Physics Letters 92, no. 11 (March 17, 2008): 112112. http://dx.doi.org/10.1063/1.2892658.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Kung, Chun Haow, Beniamin Zahiri, Pradeep Kumar Sow, and Walter Mérida. "Electrochemical Wettability Control on Cu/CuxO Core-Shell Dendrites: In-Situ Droplet Modulation and On-Demand Oil-Water Separation." MRS Advances 3, no. 53 (2018): 3163–69. http://dx.doi.org/10.1557/adv.2018.335.

Full text

Abstract:

ABSTRACTStimuli-responsive materials with controlled reversible wettability find diverse application as self-cleaning surfaces, tunable optical lenses and microfluidic devices. We report on an electrochemical approach for dynamic control over the wetting properties of additive-free Cu/CuxO core-shell dendritic structures. By varying the oxidation state of the oxide shell phase, the entire wettability range spanning superhydrophobicity (contact angle > 150°) to superhydrophilicity (contact angle < 10°) can be precisely adjusted in-situ. During the wetting transitions, the surface transforms from a low adhesive rolling state (lotus effect) to high adhesive pinning state (petal effect), and eventually to superhydrophilic state with a water-absorbing ability (fish scale wetting). The wetting alteration is reversible via air-drying at room temperature or mild heat drying at 100°C. The reversibly redox-driven wettability switching is demonstrated for controllable oil-water separation with efficiency higher than 98 percent.

APA, Harvard, Vancouver, ISO, and other styles

17

Yang, Yang, Kezhi Li, and Chun Zhao. "Ablation mechanism and morphology evolution of the HfC-SiC coating for C/C composites deposited by supersonic atmospheric plasma spraying." Advanced Composites Letters 28 (January 1, 2019): 096369351986994. http://dx.doi.org/10.1177/0963693519869944.

Full text

Abstract:

HfC-SiC protective coating was deposited on the surface of SiC-coated carbon/carbon composites by supersonic atmospheric plasma spraying due to the high arc temperature and the efficient deposition rate. The morphology and microstructure of the HfC-SiC coating were analyzed by X-ray diffraction and scanning electron microscopy. The results showed that Hf and Si elements distributed uniformly in the coating and the coating was dense without crack. Ablation resistance test was processed by oxyacetylene torch. During the ablation process, the sintering rate of HfO2 was slow, and more oxygen diffused into the internal coating, which caused the oxidation of the internal coating and damaged the structure of internal coating in the ablation center region. In addition, during cooling process, a new phase HfSiO4 was generated by the reaction between HfO2 and SiO2, which acted as a pinning agent to prevent the further expansion of the crack.

APA, Harvard, Vancouver, ISO, and other styles

18

Lü, Zhi Jie, Jun Zhao, and Wei Min Wang. "Microstructure and Wear Behavior of Si₃N₄/TiC Nanocomposite Ceramic Tool Material." Advanced Materials Research 279 (July 2011): 54–60. http://dx.doi.org/10.4028/www.scientific.net/amr.279.54.

Full text

Abstract:

Si3N4/TiC nanocomposite cutting tool materials were fabricated by adding Si3N4 and Al2O3 nanocomposites with Al2O3 and Y2O3 as additives. The microstructures of materials were analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and then wear resistance of Si3N4/TiC nanocomposite cutting tool materials was studied when machining cast iron and quenched steel in continuous dry turning experiments. Micrographs of the worn tools materials were observed with SEM. Results showed that TiC nanoparticles distribute in the matrix grains and lead to the crack deflection as well as crack pinning. Due to TiC nanoparticles and β-Si3N4 quasiwhiskers, the crack trajectories exhibited crack deflection, rod-like grain bridging and pull-out. Wear mode of Si3N4/TiC inserts is mainly abrasive wear with slighter adhesive wear when machining cast iron. The dominant wear patterns during the cutting of quenched steel were adhesion, abrasion, as well as oxidation and diffusion under high temperature.

APA, Harvard, Vancouver, ISO, and other styles

19

Nakano, Yoshitaka, and Noboru Ichinose. "Oxygen adsorption and VDR effect in (Sr, Ca)TiO3−x based ceramics." Journal of Materials Research 5, no. 12 (December 1990): 2910–22. http://dx.doi.org/10.1557/jmr.1990.2910.

Full text

Abstract:

The relation between the oxygen adsorption and the voltage dependence of the resistor (VDR effect) in (Sr, Ca)TiO3−x based ceramics has been investigated. The nonlinearity of the voltage-current characteristics increased with increasing the barrier height, which is thought to be generated by the oxygen chemisorption. Acceptor type trap levels were detected by means of a zero biased DLTS technique at high temperatures. These interfacial energy levels changed with reoxidizing temperatures, and the change can be explained by the degradation of the chernisorbed oxygen. The high temperature type of the chemisorbed oxygen as O2− and O is relatively stable due to the strong pinning effect of trapped electrons, with reoxidizing anneals of grain surfaces above the oxidation temperature, and it contributes greatly to the VDR effect. It is concluded that energy barriers are caused by the interface states generated by the chemisorbed oxygen on grain surfaces and that they determine the VDR effect.

APA, Harvard, Vancouver, ISO, and other styles

20

Khomiakova, Natalia, Jan Hanuš, Anna Kuzminova, and Ondřej Kylián. "Investigation of Wettability, Drying and Water Condensation on Polyimide (Kapton) Films Treated by Atmospheric Pressure Air Dielectric Barrier Discharge." Coatings 10, no. 7 (June 29, 2020): 619. http://dx.doi.org/10.3390/coatings10070619.

Full text

Abstract:

In this study, we report on the investigation of influence of air atmospheric pressure dielectric barrier discharge on polyimide (Kapton) films. It is shown that plasma treatment causes a significant increase of Kapton wettability that is connected with alterations of its chemical composition (oxidation) induced by dielectric barrier discharge. Observed variations in the wettability of Kapton were also found to be accompanied by changes in the dynamics of water droplets drying on plasma-treated Kapton, namely by the reduction of the constant contact angle phase of the droplet drying. This effect may be ascribed to the higher surface heterogeneity of plasma-treated Kapton that causes pinning of the edges of drying droplet on the Kapton surface. Finally, the differences in wettability induced by the plasma treatment led to a different way, how the water condensates on the Kapton surface: while the condensing water forms large amount of small droplets on untreated Kapton, much bigger water structures were found on the Kapton exposed to atmospheric plasma.

APA, Harvard, Vancouver, ISO, and other styles

21

Novarina, Daniele, Ridhdhi Desai, Jessica A. Vaisica, Jiongwen Ou, Mohammed Bellaoui, Grant W. Brown, and Michael Chang. "A Genome-Wide Screen for Genes Affecting Spontaneous Direct-Repeat Recombination in Saccharomyces cerevisiae." G3: Genes|Genomes|Genetics 10, no. 6 (April 7, 2020): 1853–67. http://dx.doi.org/10.1534/g3.120.401137.

Full text

Abstract:

Homologous recombination is an important mechanism for genome integrity maintenance, and several homologous recombination genes are mutated in various cancers and cancer-prone syndromes. However, since in some cases homologous recombination can lead to mutagenic outcomes, this pathway must be tightly regulated, and mitotic hyper-recombination is a hallmark of genomic instability. We performed two screens in Saccharomyces cerevisiae for genes that, when deleted, cause hyper-recombination between direct repeats. One was performed with the classical patch and replica-plating method. The other was performed with a high-throughput replica-pinning technique that was designed to detect low-frequency events. This approach allowed us to validate the high-throughput replica-pinning methodology independently of the replicative aging context in which it was developed. Furthermore, by combining the two approaches, we were able to identify and validate 35 genes whose deletion causes elevated spontaneous direct-repeat recombination. Among these are mismatch repair genes, the Sgs1-Top3-Rmi1 complex, the RNase H2 complex, genes involved in the oxidative stress response, and a number of other DNA replication, repair and recombination genes. Since several of our hits are evolutionarily conserved, and repeated elements constitute a significant fraction of mammalian genomes, our work might be relevant for understanding genome integrity maintenance in humans.

APA, Harvard, Vancouver, ISO, and other styles

22

Motowidlo, L. R., P. J. Lee, C. Tarantini, S. Balachandran, A. K. Ghosh, and D. C. Larbalestier. "An intermetallic powder-in-tube approach to increased flux-pinning in Nb3Sn by internal oxidation of Zr." Superconductor Science and Technology 31, no. 1 (November 28, 2017): 014002. http://dx.doi.org/10.1088/1361-6668/aa980f.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Bonyadi, Yeganeh, Peter M. Gammon, Yogesh K. Sharma, Guy Baker, and Philip A. Mawby. "An Investigation into the Impact of Surface Passivation Techniques Using Metal-Semiconductor Interfaces." Materials Science Forum 897 (May 2017): 443–46. http://dx.doi.org/10.4028/www.scientific.net/msf.897.443.

Full text

Abstract:

Schottky barrier diodes (SBD) were fabricated on SiC surfaces that had been treated with different surface passivation techniques, so that metal-semiconductor analysis could be used to evaluate the quality of this surface. In this paper, we discuss the results of this study that used Current-Voltage (I-V), Capacitance-Voltage (C-V) and Current-Voltage-Temperature (I-V-T) analysis to look at the impact of untreated oxidation, Nitrous oxide (N2O) and Phosphorus Silicate Glass (PSG) treatments prior to oxide removal, and the formation of Mo, Ni and Ti diodes. While the results of this study did not reveal any consistent patterns between the different treatments, a Mo diode formed on a surface after PSG treatment, displays exceptionally low leakage (4.44×10-5 A/cm2 at 19°C; 7.26×10-4 A/cm2 at 300°C) given a low barrier height (1.27 eV). Moreover, the barrier heights extracted from C-V analysis before contact annealing show a variation across all the diodes, suggesting that the interface is greatly suffering from Fermi-Level pinning, the result of significant interface traps.

APA, Harvard, Vancouver, ISO, and other styles

24

Langelier, B., S. Y. Persaud, A. Korinek, T. Casagrande, R. C. Newman, and G. A. Botton. "Effects of boundary migration and pinning particles on intergranular oxidation revealed by 2D and 3D analytical electron microscopy." Acta Materialia 131 (June 2017): 280–95. http://dx.doi.org/10.1016/j.actamat.2017.04.003.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Babic, Vedad, Christine Geers, and Itai Panas. "Reactive Element Effects in High-Temperature Alloys Disentangled." Oxidation of Metals 93, no. 1-2 (November 23, 2019): 229–45. http://dx.doi.org/10.1007/s11085-019-09946-6.

Full text

Abstract:

AbstractReactive elements—REs—are decisive for the longevity of high-temperature alloys. This work joins several previous efforts to disentangle various RE effects in order to explain apparently contradicting experimental observations in alumina forming alloys. At 800–1000 °C, “messy” aluminum oxy-hydroxy-hydride transients initially formed due to oxidation by H2O which in turn undergo secondary oxidation by O2. The formation of the transient oxide becomes supported by dispersed RE oxide particles acting as water equivalents. At higher temperatures, electron conductivity in impurity states owing to oxygen vacancies in grain boundaries (GBs) becomes increasingly relevant. These channels are subsequently closed by REs pinning the said vacancies. The universality of the emerging understanding is supported by a comparative first-principles study by means of density functional theory addressing RE(III): Sc2O3, Y2O3, and La2O3, and RE(IV): TiO2, ZrO2, and HfO2, that upon reaction with water, co-decorate a generic GB model by hydroxide and RE ions. At 100% RE coverage, the GB model becomes relevant at both temperature regimes. Based on reaction enthalpy ΔHr considerations, “messy” aluminum oxy-hydroxy-hydride transients are accessed in both classes. Larger variations in ΔHr are found for RE(III)-decorated alumina GBs as compared to RE(IV). For RE(III), correlation with GB width is found, increasing with increased ionic radius. Similarly, upon varying RE(IV), minor changes in stability correlate with minor structural variations. GB decorations by Ce(III) and Ce(IV) further consolidate the emerging understanding. The findings are used to discuss experimental observations that include impact of co-doping by RE(III) and RE(IV).

APA, Harvard, Vancouver, ISO, and other styles

26

Bin Liang, Xingqi Liao, Bo Geng, Qishuai Zhu, Ming Yu, Jiacheng Li, Kangwei Liu, Dechang Jia, Zhihua Yang, and Yu Zhou. "A pinning effect for the enhanced oxidation resistance at 1600 °C of silicoboron carbonitride ceramics with the addition of MXene." Corrosion Science 196 (March 2022): 110041. http://dx.doi.org/10.1016/j.corsci.2021.110041.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Staerz, Anna, Inci Boehme, David Degler, Mounib Bahri, Dmitry Doronkin, Anna Zimina, Helena Brinkmann, et al. "Rhodium Oxide Surface-Loaded Gas Sensors." Nanomaterials 8, no. 11 (November 1, 2018): 892. http://dx.doi.org/10.3390/nano8110892.

Full text

Abstract:

In order to increase their stability and tune-sensing characteristics, metal oxides are often surface-loaded with noble metals. Although a great deal of empirical work shows that surface-loading with noble metals drastically changes sensing characteristics, little information exists on the mechanism. Here, a systematic study of sensors based on rhodium-loaded WO3, SnO2, and In2O3—examined using X-ray diffraction, high-resolution scanning transmission electron microscopy, direct current (DC) resistance measurements, operando diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, and operando X-ray absorption spectroscopy—is presented. Under normal sensing conditions, the rhodium clusters were oxidized. Significant evidence is provided that, in this case, the sensing is dominated by a Fermi-level pinning mechanism, i.e., the reaction with the target gas takes place on the noble-metal cluster, changing its oxidation state. As a result, the heterojunction between the oxidized rhodium clusters and the base metal oxide was altered and a change in the resistance was detected. Through measurements done in low-oxygen background, it was possible to induce a mechanism switch by reducing the clusters to their metallic state. At this point, there was a significant drop in the overall resistance, and the reaction between the target gas and the base material was again visible. For decades, noble metal loading was used to change the characteristics of metal-oxide-based sensors. The study presented here is an attempt to clarify the mechanism responsible for the change. Generalities are shown between the sensing mechanisms of different supporting materials loaded with rhodium, and sample-specific aspects that must be considered are identified.

APA, Harvard, Vancouver, ISO, and other styles

28

Kent, Tyler, Mary Edmonds, Ravi Droopad, and Andrew C. Kummel. "InGaAs (110) Surface Cleaning Using Atomic Hydrogen." Solid State Phenomena 219 (September 2014): 47–51. http://dx.doi.org/10.4028/www.scientific.net/ssp.219.47.

Full text

Abstract:

A major obstacle facing III-V semiconductor based metal oxide semiconductor field effect transistors (MOSFETs) is the large density of trap states that exist at the semiconductor/oxide interface.[1] These trap states can pin the Fermi level preventing the MOSFET from acting as a switch in logic devices. Several sources of Fermi level pinning have been proposed including oxidation of the III-V substrate.[2, 3] In order to minimize the presence of III-V oxides it is crucial to employ either an ex-situ etch or to use an in-situ method such as atomic hydrogen cleaning.[4, 5] Although atomic H cleaning of III-V surfaces is well known, it has never been demonstrated on InGaAs (110) crystallographic faces. Furthermore, tri-gate field effect transistors (finFETs) have recently been employed in commercially available logic chips.[6] This unique device architecture allows for a reduction in short channel effects, minimization of the subthreshold swing, and a higher transconductance.[7] The InGaAs (110) surface would be the sidewalls of a vertically aligned (001) based finFETs.[8] Therefore, it is essential to find an in-situ method to efficiently remove any oxides or contamination from the (110) surfaces that is also compatible with the (001) surface. In this study, STM was employed to determine if atomic hydrogen can be used to remove the native oxide from air exposed InGaAs (110) samples. A post clean anneal was used to restore the surface to molecular beam epitaxy (MBE) levels of cleanliness.

APA, Harvard, Vancouver, ISO, and other styles

29

Ashby, Carol I. H., John P. Sullivan, Nancy A. Missert, Paula P. Newcomer, Hong Q. Hou, B. E. Hammons, Michael J. Hafich, and Albert G. Baca. "Interfacial Arsenic from Wet Oxidation of AlxGa1-xAs/GaAs: Its Effects on Electronic Properties and New Approaches to Mis Device Fabrication." MRS Proceedings 448 (1996). http://dx.doi.org/10.1557/proc-448-285.

Full text

Abstract:

AbstractThree important oxidation regimes have been identified in the temporal evolution of the wet thermal oxidation of AlxGa1-xAs (1 ≥ x ≥ 0.90) on GaAs: 1) oxidation of Al and Ga in the AlxGa1-xAs alloy to form an amorphous oxide layer, 2) oxidative formation and elimination of elemental As (both crystalline and amorphous) and of amorphous As2O3, and 3) crystallization of the oxide film. Residual As can result in up to a 100-fold increase in leakage current and a 30% increase in the dielectric constant and produce strong Fermi-level pinning and high leakage currents at the oxidized AlxGa1-xAs/GaAs interface. The presence of thermodynamically-favored interfacial As may impose a fundamental limitation on the application of AlGaAs wet oxidation for achieving MIS devices in the GaAs material system.

APA, Harvard, Vancouver, ISO, and other styles

30

Wu, Tianze, Xiao Ren, Yuanmiao Sun, Shengnan Sun, Guoyu Xian, Günther G. Scherer, Adrian C. Fisher, et al. "Spin pinning effect to reconstructed oxyhydroxide layer on ferromagnetic oxides for enhanced water oxidation." Nature Communications 12, no. 1 (June 15, 2021). http://dx.doi.org/10.1038/s41467-021-23896-1.

Full text

Abstract:

AbstractProducing hydrogen by water electrolysis suffers from the kinetic barriers in the oxygen evolution reaction (OER) that limits the overall efficiency. With spin-dependent kinetics in OER, to manipulate the spin ordering of ferromagnetic OER catalysts (e.g., by magnetization) can reduce the kinetic barrier. However, most active OER catalysts are not ferromagnetic, which makes the spin manipulation challenging. In this work, we report a strategy with spin pinning effect to make the spins in paramagnetic oxyhydroxides more aligned for higher intrinsic OER activity. The spin pinning effect is established in oxideFM/oxyhydroxide interface which is realized by a controlled surface reconstruction of ferromagnetic oxides. Under spin pinning, simple magnetization further increases the spin alignment and thus the OER activity, which validates the spin effect in rate-limiting OER step. The spin polarization in OER highly relies on oxyl radicals (O∙) created by 1st dehydrogenation to reduce the barrier for subsequent O-O coupling.

APA, Harvard, Vancouver, ISO, and other styles

31

Wang, Jinfang, Dunwen Zuo, Liu Zhu, Zhibiao Tu, Xiao Lin, Yinan Wu, Weiwei Li, and Xiaoqiong Zhang. "Effect of Y2O3 Addition on High-Temperature Oxidation of Binderless Tungsten Carbide." Frontiers in Materials 8 (March 16, 2021). http://dx.doi.org/10.3389/fmats.2021.645612.

Full text

Abstract:

High-temperature oxidation tests were carried out on binderless tungsten carbide (WC) with different Y2O3 contents (0, 1, 2, 3, and 4 wt.%) and on YG3 cemented carbide. Results demonstrated that the addition of Y2O3 led to a significant improvement in the high-temperature oxidation resistance of binderless tungsten carbide compared with those of YG3 cemented carbide and pure tungsten carbide. After oxidation at 800°C for 120 min, the oxidation weight gain of binderless tungsten carbide with 1 wt.% Y2O3 was 58.54 mg cm−2, corresponding to the reduction by 47.7% compared with YG3 cemented carbide. In the high temperature oxidation process, WC in the triangle grain boundary was first oxidized to Y2WO6 due to the high activity of Y2O3 which is present mainly in the WC grain boundaries. The transport of W4+ outward along the grain boundary and the diffusion of O2− inward along the grain boundary were hindered by Y2WO6 with the high ionic radius and thus the antioxidant capacity of binderless tungsten carbide was improved. Meanwhile, the adhesive ability of oxidation layer on the substrate was enhanced with the “pinning effect” of Y2WO6, which also led to the improvement of oxidation resistance. With the Y2O3 content increasing from 1 to 4 wt.%, the antioxidant properties of binderless tungsten carbide gradually declined, and the antioxidant performance of binderless tungsten carbide with 1 wt.% Y2O3 was found to be the best.

APA, Harvard, Vancouver, ISO, and other styles

32

Albao, Marvin A., Da-Jiang Liu, Cheol H. Choi, Mark S. Gordon, and J. W. Evans. "Competitive Etching and Oxidation of Vicinal Si(100) Surfaces." MRS Proceedings 859 (2004). http://dx.doi.org/10.1557/proc-859-jj3.6.

Full text

Abstract:

ABSTRACTExposure of a vicinal Si(100) surface to oxygen at around 550 C produces etching-mediated step recession. In addition, some oxide islands are formed which locally pin receding steps. We develop an atomistic lattice-gas model for this process which accounts for the interplay between oxygen surface chemistry (adsorption, diffusion, oxide formation, and etching via SiO desorption) and the silicon surface and step dynamics (anisotropic diffusion and aggregation of di-vacancies formed by etching, and ad-dimer attachment-detachment dynamics at steps incorporating anisotropic energetics). Kinetic Monte Carlo simulation of this model produces step morphologies retaining some qualitative but not quantitative features of their equilibrium structure (alternating rough SB steps and smooth SA steps), except for pinning which produces protruding “fingers”. These features are seen in Scanning Tunneling Microscopy studies.

APA, Harvard, Vancouver, ISO, and other styles

33

McDowell, C. S., S. N. Basu, and T. Ando. "Processing and Oxidation of Nitride Stabilized 18Cr-20Ni Stainless Steel." MRS Proceedings 362 (1994). http://dx.doi.org/10.1557/proc-362-111.

Full text

Abstract:

AbstractThe present investigation explores the use of nitride precipitates for grain-size stabilization in a 18Cr-2ONi austenitic stainless steel for high temperature applications in oxidizing atmospheres. The potential for reductions in alloying contents of such steels has become a focus of research out of concern for the conservation of strategic alloying elements such as Cr. In order for the alloy to maintain superior oxidation resistance, it must sustain a fine grain size by virtue of effective grain boundary pinning by stable precipitates.Al and Ti microalloyed 18Cr-20Ni steels have been nitrided using rapid solidification processing (spray forming) and subjected to thermomechanical treatments to precipitate nitrides from the supersaturated solid solutions. The spray formed deposits were cold rolled to increase the density of dislocations, which act as sites for nucleation of nitride precipitates. The alloys were then annealed to nucleate and grow the precipitates, followed by cold rolling and recrystallization to generate a stable, fine grained microstructure. The Ti-microalloyed steel demonstrated high-temperature grain size stability by maintaining a grain size of≈7μm after 600h at 1000°C.The Ti-microalloyed steel has been subjected to isothermal oxidation in air at 900°C. The results of preliminary oxidation experiments are reported. The spray deposited and thermomechanically processed alloy demonstrated high-temperature oxidation behavior superior to conventionally processed (hot rolled and annealed) alloys.

APA, Harvard, Vancouver, ISO, and other styles

34

Chen, Yi-Hsun, Chih-Yi Cheng, Shao-Yu Chen, Jan Sebastian Dominic Rodriguez, Han-Ting Liao, Kenji Watanabe, Takashi Taniguchi, et al. "Oxidized-monolayer tunneling barrier for strong Fermi-level depinning in layered InSe transistors." npj 2D Materials and Applications 3, no. 1 (December 2019). http://dx.doi.org/10.1038/s41699-019-0133-3.

Full text

Abstract:

AbstractIn two-dimensional (2D)-semiconductor-based field-effect transistors and optoelectronic devices, metal–semiconductor junctions are one of the crucial factors determining device performance. The Fermi-level (FL) pinning effect, which commonly caused by interfacial gap states, severely limits the tunability of junction characteristics, including barrier height and contact resistance. A tunneling contact scheme has been suggested to address the FL pinning issue in metal–2D-semiconductor junctions, whereas the experimental realization is still elusive. Here, we show that an oxidized-monolayer-enabled tunneling barrier can realize a pronounced FL depinning in indium selenide (InSe) transistors, exhibiting a large pinning factor of 0.5 and a highly modulated Schottky barrier height. The FL depinning can be attributed to the suppression of metal- and disorder-induced gap states as a result of the high-quality tunneling contacts. Structural characterizations indicate uniform and atomically thin-surface oxidation layer inherent from nature of van der Waals materials and atomically sharp oxide–2D-semiconductor interfaces. Moreover, by effectively lowering the Schottky barrier height, we achieve an electron mobility of 2160 cm2/Vs and a contact barrier of 65 meV in two-terminal InSe transistors. The realization of strong FL depinning in high-mobility InSe transistors with the oxidized-monolayer presents a viable strategy to exploit layered semiconductors in contact engineering for advanced electronics and optoelectronics.

APA, Harvard, Vancouver, ISO, and other styles

35

Janes, D. B., S. Hong, V. R. Kolagunta, D. McInturff, T. B. NG, R. Reifenberger, S. D. West, and J. M. Woodall. "Chemically Stable Semiconductor Surface Layers Using Low-Temperature Grown GaAs." MRS Proceedings 448 (1996). http://dx.doi.org/10.1557/proc-448-3.

Full text

Abstract:

AbstractThe chemical stability of a GaAs layer structure consisting of a thin (10 nm) layer of low-temperature-grown GaAs (LTG:GaAs) on a heavily n-doped GaAs layer, both grown by molecular beam epitaxy, is described. Scanning tunneling spectroscopy and X-ray photoelectron spectroscopy performed after atmospheric exposure indicate that the LTG:GaAs surface layer oxidizes much less rapidly than comparable layers of stoichiometric GaAs. There is also evidence that the terminal oxide thickness is smaller than that of stoichiometric GaAs. The spectroscopy results are used to confirm a model for conduction in low resistance, nonalloyed contacts employing comparable layer structures. The inhibited surface oxidation rate is attributed to the bulk Fermi level pinning and the low minority carrier lifetime in unannealed LTG:GaAs. Device applications including low-resistance cap layers for field-effect transistors are described.

APA, Harvard, Vancouver, ISO, and other styles

36

Hara, S., T. Teraji, H. Okushi, and K. Kajimura. "New Technique for Ohmic Formation." MRS Proceedings 427 (1996). http://dx.doi.org/10.1557/proc-427-159.

Full text

Abstract:

AbstractWe propose a new systematical method to control Schottky barrier heights of metal/semiconductor interfaces by controlling the density of interface electronic states and the number of charges in the states. The density of interface states is controlled by changing the density of surface electronic states, which is controlled by surface hydrogenation and flattening the surface atomically. We apply establishing hydrogen termination techniques using a chemical solution, pH controlled buffered HF or hot water. Also, slow oxidation by oxygen gas was used to flatten resultant semiconductor surfaces. The density of interface charges is changeable by controlling a metal work function. When the density of surface states is reduced enough to unpin the Fermi level, the barrier height is determined simply by the difference between the work function of a metal φm and the flat-band semiconductor ØsFB. In such an interface with the low density of interface states, an Ohmic contact with a zero barrier height is formed when we select a metal with φm < φsFB. We have already demonstrated controlling Schottky and Ohmic properties by changing the pinning degree on silicon carbide (0001) surfaces. Further, on an atomically-flat Si(111) surface with monohydride termination, we have observed the lowering of an Al barrier height.

APA, Harvard, Vancouver, ISO, and other styles

37

Pittkowski, Rebecca, Spyridon Divanis, Mariana Klementová, Roman Nebel, Shahin Nikman, Harry Hoster, Sanjeev Mukerjee, Jan Rossmeisl, and Petr Krtil. "Engendering Unprecedented Activation of Oxygen Evolution via Rational Pinning of Ni Oxidation State in Prototypical Perovskite: Close Juxtaposition of Synthetic Approach and Theoretical Conception." ACS Catalysis, January 6, 2021, 985–97. http://dx.doi.org/10.1021/acscatal.0c04733.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Cho, EunKyung, Pae Wu, Minhaz Ahmed, April Brown, and T. F. Kuech. "Characterization of immobilized DNA on sulfur-passivated InAs surfaces." MRS Proceedings 1301 (2011). http://dx.doi.org/10.1557/opl.2011.75.

Full text

Abstract:

ABSTRACTThe immobilization of DNA on passivated n-type InAs (100) surfaces has been studied using X-ray and ultraviolet photoelectron spectroscopy. The benefits of sulfur passivation using ammonium sulfide solution ((NH4)2S) for DNA immobilization were examined. The XPS/UPS data carried out on non-functionalized and functionalized surfaces demonstrate that the DNA probes reacted with the sulfur-passivated InAs surface. The XPS data in combination with fluorescently-tagged DNA indicate that the sulfur passivation process leads to a higher and more uniform attachment of DNA over the surface compared to non-sulfur-passivated InAs surfaces. The XPS data obtained immediately after sulfur passivation clearly observes In-S bonding, with little or no As-S. In addition, the XPS spectra of As 3d core-levels immediately after sulfur passivation shows that there is a negligible amount of As-Ox, but the peak become considerable after exposure to the aqueous DNA probe solution. The increase in As-Ox is likely due to the presence of non-sulfur bonded As atoms present on the surface. The presence of sulfur on the surface does lead to the high areal density of attached ssDNA. This system forms the basis of a DNA sensing system. While chemically passivating the surface against oxidation and facilitating probe attachment, the changes in Fermi level position were also monitored by UPS. UPS spectra show that the Fermi level of a clean InAs surface is located ~0.6 eV above the valence band maximum. The changes in electronic states induced by sulfur passivation and the pinning of EF are discussed.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Pinnick oxidation'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles