Articoli di riviste: "Oxide"

1

She, Weiqing, Zhenzhen Xu, Lianjie Zhai, Junlin Zhang, Jie Huang, Weiqiang Pang e Bozhou Wang. "Synthetic Methods Towards Energetic Heterocyclic N-Oxides via Several Cyclization Reactions". Crystals 12, n. 10 (25 settembre 2022): 1354. http://dx.doi.org/10.3390/cryst12101354.

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Due to the introduction of oxygen atoms, N-oxide energetic compounds have a unique oxygen balance, excellent detonation properties, and a high energy density, attracting the extensive attention of researchers all over the world. N-oxides are classified into two categories based on the structural characteristics of their skeletons: azine N-oxides and azole N-oxides, whose N→O coordination bonds are formed during cyclization. There are six kinds of azine N-oxides, namely 1,2,3,4-tetrazine-1,3-dioxide, 1,2,3,5-tetrazine-2-oxide, 1,2,3-triazine-3-oxide, 1,2,3-triazine-2-oxide, pyridazine-1,2-dioxide, and pyrazine-1-oxide. Azole N-oxides include 1,2,5-oxadiazole-2-oxide, pyrazole-1-oxide, and triazole-1-oxide. Synthetic strategies towards these two categories of N-oxides are fully reviewed. Corresponding reaction mechanisms towards the aromatic N-oxide frameworks and examples that use the frameworks to create high-energy substances are discussed. Moreover, the energetic properties of N-oxide energetic compounds are compared and summarized.

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2

Möhrle, H., e R. Nießen. "Reaktionen von Isochinolinium-Salzen mit Hydroxylamin-Derivaten, 2. Mitteilung N-(Alkyl)- und N-(Aryl)-substituierte Verbindungen / Reactions of Isoquinolinium Salts with Hydroxylamine Derivatives, 2nd Communication N-(Alkyl) and N-(Aryl) Substituted Compounds". Zeitschrift für Naturforschung B 54, n. 4 (1 aprile 1999): 532–40. http://dx.doi.org/10.1515/znb-1999-0417.

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The N -alkyl- and N -aryl-isoquinolinium salts 7, 15-17 reacted with free hydroxylamine in pyridine to give the isoquinoline-2-oxide (9) as final product. The intermediate dioximes 8 were isolated and characterized by derivatisation with acetic anhydride to the oxime ester nitrile 10. From the reaction o f 8 with trifluoroacetic anhydride/triethylam ine 3-amino-isoquinoline- 2-oxide (12) resulted after hydrolysis. Due to the electronic influence the 5-nitroisoquinolinium salts 1 -3 react faster than the 5-hydroxy derivative 20. but with the same course of conversion via dioximes to amine oxides. An optimized method for preparation of the amine oxides was developed .

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3

Kim, Youngsun, Donghee Choi, Hosun Jang, Changsu Na, Moonhyeon Hwang, Joohyun Cho, Kyoungin Lee, Sunmin Kim, Byoungsik Pyo e Daehwan Youn. "Effects of Acupuncture at ST41, BL60, GB38 on Changes of Nitric Oxide and Nitric Oxide Synthase in Rats". Korean Journal of Acupuncture 30, n. 2 (27 giugno 2013): 97–103. http://dx.doi.org/10.14406/acu.2013.30.2.097.

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4

Cha, Wu-Shin, Junsik Lee, Malkeshkumar Patel, Kibum Lee e Joondong Kim. "Flexible and Transparent Heater with Oxide/Metal/Oxide Structure". Transactions of The Korean Institute of Electrical Engineers 72, n. 1 (31 gennaio 2023): 87–92. http://dx.doi.org/10.5370/kiee.2023.72.1.87.

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5

Majhi, Sanjit Manohar, Ali Mirzaei, Hyoun Woo Kim e Sang Sub Kim. "Reduced Graphene Oxide (rGO)-Loaded Metal-Oxide Nanofiber Gas Sensors: An Overview". Sensors 21, n. 4 (14 febbraio 2021): 1352. http://dx.doi.org/10.3390/s21041352.

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Reduced graphene oxide (rGO) is a reduced form of graphene oxide used extensively in gas sensing applications. On the other hand, in its pristine form, graphene has shortages and is generally utilized in combination with other metal oxides to improve gas sensing capabilities. There are different ways of adding rGO to different metal oxides with various morphologies. This study focuses on rGO-loaded metal oxide nanofiber (NF) synthesized using an electrospinning method. Different amounts of rGO were added to the metal oxide precursors, and after electrospinning, the gas response is enhanced through different sensing mechanisms. This review paper discusses rGO-loaded metal oxide NFs gas sensors.

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6

Novosyolov, A., I. Olianina, I. Novoselova, Y. Vasina, Y. Ershova, T. Loik e Yu Kudelina. "RESEARCH OF THE POSSIBILITY OF REDUCING THE CIRCULATION OF SULFUR OXIDE IN THE PRODUCTION OF WHITE CEMENT". Bulletin of Belgorod State Technological University named after. V. G. Shukhov 6, n. 7 (10 luglio 2021): 89–98. http://dx.doi.org/10.34031/2071-7318-2021-6-7-89-98.

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The article discusses the possibility of reducing the circulation of sulfur oxide in the production of white cement by introducing alkaline potassium oxides K2O and sodium Na2O. A decrease in the circulation of sulfur oxide SO3 is achieved by increasing its yield in the clinker by transferring SO3 from a more sublimated compound of calcium sulfate CaSO4 to less sublimated potassium sulfates K2SO4 and sodium Na2SO4. Potassium and sodium oxides are introduced in the composition of carbonates and feldspar. The amount of introduced alkali oxides is controlled by the molar ratio A/S between sulfur oxide SO3 and alkaline oxides K2O and Na2O. It is shown that with the same molar ratio between sulfur oxide and alkaline oxides, the amount of SO3 removed with clinker depends on the ratio between potassium and sodium oxides. The higher the sodium oxide content, the more sulfur oxide comes out with the clinker and less remains to circulate in the kiln. The sublimation of sulfur oxide decreases from 70.5% - without the introduction of alkaline oxides, to 38,5 % at the maximum A/S ratio with the addition of potassium and sodium oxides in a ratio of 80:20 %. When potassium and sodium oxides are added in a ratio of 20:80%, the sublimation of sulfur oxide is reduced to 7,7 % at the same A/S ratio.

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7

Pourroy, G., J. L. Guille e P. Poix. "Reactivity of metal oxides copper(I) oxide, manganese(II) oxide, cobalt(II) oxide, nickel(II) oxide, copper(II) oxide and zinc oxide with indialite". Chemistry of Materials 2, n. 2 (marzo 1990): 101–5. http://dx.doi.org/10.1021/cm00008a007.

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8

Li, Huaying, e Aichun Zhao. "Pickling Behavior of Duplex Stainless Steel 2205 in Hydrochloric Acid Solution". Advances in Materials Science and Engineering 2019 (25 febbraio 2019): 1–6. http://dx.doi.org/10.1155/2019/9754528.

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The oxide-scale structure and pickling behavior of oxided 2205 duplex stainless steel in the electrolytes containing hydrochloric acid were investigated. The oxide scales mainly consist of two layers: the outer layer is dense Fe2O3, and the inner granular is FeCr2O4 spinel. During the pickling process, pittings form around the boundaries of FeCr2O4 particles or interfaces of two kinds of oxides, which results in that the electrolyte can directly react with the chromium-depleted layer along the pittings to produce an “undercut” effect so that the pickling efficiency is improved markedly. The pickling mechanism was discussed, and the model was established.

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9

Read, RW, e WP Norris. "The Nucleophilic Substitution Reactions of 5- and 7-Chloro-4,6-dinitrobenzofurazan 1-Oxide by Aromatic Amines." Australian Journal of Chemistry 38, n. 3 (1985): 435. http://dx.doi.org/10.1071/ch9850435.

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7-Chloro-4,6-dinitrobenzofurazan 1-oxide is a powerful electrophile which reacts with a variety of primary and secondary aromatic amines, even those with deactivating substituents , to give arylamino - benzofurazan oxides under mild conditions. Tertiary aromatic amines react through carbon to give aminoarylbenzofurazan oxides. During, or as a consequence of, the substitution reactions, tautomerism occurs to give in all but one example an equilibrium mixture of 5- and 7-substituted 4,6-dinitrobenzofurazan oxides in which the latter predominates. Thus 5-chloro-4,6-dinitrobenzofurazan 1-oxide and 7- chloro-4,6-dinitrobenzofurazan 1-oxide both react with aniline to yield the same isomeric mixture of products: 4,6-dinitro-7- phenylaminobenzofurazan oxide (predominantly 1-oxide) (major) and 4,6- dinitro-5-phenylaminobenzofurazan 1-oxide (minor). The 5- and 7- phenylamino 4,6-dinitrobenzofurazans were prepared to assist in structural assignment of the N-oxides.

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10

Navrotsky, Alexandra, e Anastasia Koryttseva. "Acid–Base Properties of Oxides Derived from Oxide Melt Solution Calorimetry". Molecules 28, n. 12 (7 giugno 2023): 4623. http://dx.doi.org/10.3390/molecules28124623.

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The paper analyzes the relationships among acid–base interactions in various oxide systems and their thermodynamics. Extensive data on enthalpies of solution of binary oxides in oxide melts of several compositions, obtained by high-temperature oxide melt solution calorimetry at 700 and 800 °C, are systematized and analyzed. Oxides with low electronegativity, namely the alkali and alkaline earth oxides, which are strong oxide ion donors, show enthalpies of solution that have negative values greater than −100 kJ per mole of oxide ion. Their enthalpies of solution become more negative with decreasing electronegativity in the order Li, Na, K and Mg, Ca, Sr, Ba in both of the commonly used molten oxide calorimetric solvents: sodium molybdate and lead borate. Oxides with high electronegativity, including P2O5, SiO2, GeO2, and other acidic oxides, dissolve more exothermically in the less acidic solvent (lead borate). The remaining oxides, with intermediate electronegativity (amphoteric oxides) have enthalpies of solution of between +50 and −100 kJ/mol, with many close to zero. More limited data for the enthalpies of solution of oxides in multicomponent aluminosilicate melts at higher temperature are also discussed. Overall, the ionic model combined with the Lux–Flood description of acid–base reactions provide a consistent and useful interpretation of the data and their application for understanding the thermodynamic stability of ternary oxide systems in solid and liquid states.

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11

Möhrle, H., e R. Nießen. "Reaktionen von Isochinolinium-Salzen mit Hydroxylamin-Derivaten, 3. Mitteilung. Mechanismus der Aminoxid-Bildung / Reactions of Isoquinolinium Salts with Hydroxylamine Derivatives, 3rd Communication. Mechanism of Amine Oxide Generation". Zeitschrift für Naturforschung B 54, n. 7 (1 luglio 1999): 913–22. http://dx.doi.org/10.1515/znb-1999-0715.

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2-Methylpapaverinium iodide (1) reacted with hydroxylamine to papaverine-N-oxide (2), but without a detectable intermediate and only in moderate yield, caused by the steric hindrance of the 1-substituent. The ring opened product of 2-dinitrophenylisoquinolinium salt with hydroxylamine, the enamine-oxime 3b gave rise to a 3-substituted cyclic nitrone (6), when heated with triethylamine. This alkali-stable compound was transformed with acid quantitatively to isoquinoline-N-oxide (4). The enaminonitrile 9c, treated with triethylamine showed cyclization to the iminoisoquinoline 10, which by loss of nitrous acid produced the tetracyclic azaindole 11. The 2-methoxyisoquinolinium salt 16 was cleaved with O-methylhydroxylamine to the resistant di(O-methyloximes) (20a/b), unable to form the amine oxide 4. From these and former results, a mechanism for the ring opening of cycliminium salts and the recyclization to amine oxides was proposed.

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12

Ramesh, Ramamoorthy, e Darrell G. Schlom. "Whither Oxide Electronics?" MRS Bulletin 33, n. 11 (novembre 2008): 1006–14. http://dx.doi.org/10.1557/mrs2008.220.

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AbstractIn this issue we have endeavored to answer the question, “Whither oxide electronics?” This issue provides a framework and perspective on the progress in the field of oxide electronics over the past several decades, as well as the challenges and opportunities in the years to come. Building on the foundations laid by the pioneers in the materials community and spurred by the discovery of high-temperature superconductivity, there has been both tremendous progress in understanding the complex science of oxide electronic materials and the discovery of other fascinating new phenomena, including colossal magnetoresistance, multiferrocity, and two-dimensional electron gases in correlated oxide systems. Thin-film heterostructures provide a pathway to create novel devices and combinations of physical phenomena. Indeed, the ability to synthesize and control oxide heterostructures using sophisticated deposition techniques has become a key enabler of the recent advances in this field. These oxides are beginning to enter mainstream products because of their higher performance, for example, ferroelectric memories and oxides with high dielectric constant for computers that run at higher speed and use less power.

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13

Doremus, R. H. "Diffusion of water in crystalline and glassy oxides: Diffusion–reaction model". Journal of Materials Research 14, n. 9 (settembre 1999): 3754–58. http://dx.doi.org/10.1557/jmr.1999.0508.

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Diffusion of water in oxides is modeled as resulting from the solution and diffusion of molecular water in the oxide. This dissolved water can react and exchange with the oxide network to form immobile OH groups and different hydrogen and oxygen isotopes in the oxide. The model agrees with many experiments on water diffusion in oxides. The activation energy for diffusion of water in oxides correlates with the structural openness of the oxide, suggesting that molecular water is the diffusing species.

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14

Fei, Hong Jia, e Guo Hua Yang. "Study on Sorbents Used for Hot Gas Desulfurization". Advanced Materials Research 347-353 (ottobre 2011): 3842–45. http://dx.doi.org/10.4028/www.scientific.net/amr.347-353.3842.

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This paper highlights currently excellent metal oxides used for hot gas desulfurization (HGD). Due to the different desulfurization properties, iron oxide and calcium oxide based sorbents are normally used for primary desulfurization while zinc oxide, copper oxide and manganese oxide based sorbents are often devoted to fine desulfurization. However, pure sorbents inevitably have some limitations and so, mixed oxides combining the properties of various metals like zinc ferrite and zinc titanate which get extensive concern are also introduced in this paper.

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15

Otsuka, Kiyoshi, Takahiro Tachi e Akira Morikawa. "Reduction of nitric oxide and nitrous oxide by praseodymium oxides". Reactivity of Solids 1, n. 2 (febbraio 1986): 153–64. http://dx.doi.org/10.1016/0168-7336(86)80042-0.

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16

Liu, Haiyan, Olivier Pourret, Huaming Guo, Raul E. Martinez e Lahcen Zouhri. "Impact of Hydrous Manganese and Ferric Oxides on the Behavior of Aqueous Rare Earth Elements (REE): Evidence from a Modeling Approach and Implication for the Sink of REE". International Journal of Environmental Research and Public Health 15, n. 12 (12 dicembre 2018): 2837. http://dx.doi.org/10.3390/ijerph15122837.

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In this study, models were used for the first time to investigate the fate and transport of rare earth elements (REE) in the presence of hydrous manganese and ferric oxides in groundwaters from the coastal Bohai Bay (China). Results showed that REE sorption is strongly dependent on pH, as well as hydrous manganese and ferric oxide content. Higher proportions of REE were sorbed by hydrous manganese oxide as compared to hydrous ferric oxides, for example in the presence of neodymium. In this case, a mean 28% of this element was sorbed by hydrous manganese oxide, whereas an average 7% sorption was observed with hydrous ferric oxides. A contrasting REE sorption behavior was observed with hydrous manganese and ferric oxide for all investigated groundwaters. Specifically, REE bound to hydrous manganese oxides showed decreasing sorption patterns with increasing atomic number. The opposite trend was observed in the presence of hydrous ferric oxides. In addition, these results suggested that light REE (from La to Sm) rather than heavy REE (from Eu to Lu) are preferentially scavenged by hydrous manganese oxide. However, the heavy REE showed a greater affinity for hydrous ferric oxides compared to light REE. Therefore, both hydrous manganese and ferric oxide are important scavengers of REE. This study shows the implication of hydrous manganese and ferric oxide sorption for the sink of REE in groundwater.

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17

Cochran, SJ, e FP Larkins. "An X-Ray Photoelectron Study of Doped and Supported Nickel Oxide". Australian Journal of Chemistry 38, n. 9 (1985): 1293. http://dx.doi.org/10.1071/ch9851293.

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The surfaces of lithium-and chromium-doped nickel oxide and of nickel oxide supported on alumina have been examined by X-ray photoelectron spectroscopy. The concentration of the nickel(III) species increased for the lithium-doped oxide and decreased for the chromium-doped oxide relative to the undoped oxide. The effects of doping were manifested most clearly however by the amount of oxygen-containing species adsorbed on the oxide surface rather than by variations in the nickel(III) peak intensity. Lithium-doped oxides were also shown to reduce more readily than undoped or chromium-doped oxides in the presence of carbon-containing impurities. The rate of reduction is influenced by the activation energy for electron transport which is related to the availability of the nickel(III) species. Supported oxides showed significant surface enhancement of nickel(II) as well as an absence of the nickel(III) species. The nickel(II) species in the supported oxide was not easily reduced to nickel(0).

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Lee, Hwan-Hee, Hyuk-Min Kwon, Sung-Kyu Kwon, Jae-Hyung Jang, Ho-Young Kwak, Song-Jae Lee, Sung-Yong Go, Weon-Mook Lee e Hi-Deok Lee. "Comparative Analysis of Flicker Noise and Reliability of NMOSFETs with Plasma Nitrided Oxide and Thermally Nitrided Oxide". Journal of the Korean Institute of Electrical and Electronic Material Engineers 24, n. 12 (1 dicembre 2011): 944–48. http://dx.doi.org/10.4313/jkem.2011.24.12.944.

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19

Zheng, Zheng Hua, Yong Yao Lv e Hui Ping Bai. "The Rehealing Ability of Oxide Scales on K52 Nanocrystalline Coating after Pitting Corrosion". Advanced Materials Research 538-541 (giugno 2012): 354–58. http://dx.doi.org/10.4028/www.scientific.net/amr.538-541.354.

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The rehealing ability of the oxide scales on sputter-deposited Ni-based K52 nanocrystalline coatings after pitting corrosion had been studied by polarization curves in 3.5% NaCl solution. The results indicated that the oxide scales formed on the nano-coatings exhibited excellent rehealing ability after pitting corrosion, and the rehealing oxide scales still had high corrosion resistance. The rehealing ability was declined with longer immersion time in the chloride solution. EDX analyses revealed that the oxide scales within the pits were composed of mixed-oxides. The mixed-oxides were made up of two layers: the external oxide layer was composed of Cr2O3 and TiO2 and the internal oxide layer was Al2O3.

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DUMIN, D. J. "OXIDE WEAROUT, BREAKDOWN, AND RELIABILITY". International Journal of High Speed Electronics and Systems 11, n. 03 (settembre 2001): 617–718. http://dx.doi.org/10.1142/s0129156401000988.

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The subject of oxide wearout, breakdown, and reliability will be reviewed, largely, from an historical perspective. Five topics will be discussed: oxide breakdown, oxide leakage currents, trap generation, statistics, and reliability. An early model of oxide breakdown, developed by Klein and Solomon, will be described and will be shown to be generally applicable to oxide manufactured today, and to other solid insulators, as well. Both hard and soft breakdown were included in this model and will be discussed here. The importance of stress-induced-leakage-currents (SILCs) and direct tunneling currents will be discussed in the context of device applications, thinner oxides, and oxide reliability. The diminishing importance of breakdown in ultra thin oxides in ultra small devices will be contrasted with the increasing importance of oxide leakage currents. Trap generation is important in the triggering of breakdown and in the formation of SILCs. Trap generation will be discussed in some detail. Various statistical formulations of oxide breakdown, and how these distributions are related to trap generation, will be discussed. All of these effects will be related to oxide reliability and oxide integrity. An extensive bibliography has been included to help the reader obtain more detailed information concerning the concepts being discussed.

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21

Grieb, Michael, Masato Noborio, Dethard Peters, Anton J. Bauer, Peter Friedrichs, Tsunenobu Kimoto e Heiner Ryssel. "Comparison of the Threshold-Voltage Stability of SiC MOSFETs with Thermally Grown and Deposited Gate Oxides". Materials Science Forum 645-648 (aprile 2010): 681–84. http://dx.doi.org/10.4028/www.scientific.net/msf.645-648.681.

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The electrical characteristics and the reliability of different oxides on the 4H-SiC Si-face for gate oxide application in MOS devices are compared under MOSFET operation conditions at room temperature, at 100°C and at 130°C. The oxides are either an 80nm thick deposited oxide annealed in NO or an 80nm thick grown oxide in diluted N2O. The deposited oxide shows significant higher QBD- and lower Dit-values as well as a stronger decrease of drain current under stress than the grown oxide. Although for the deposited oxide, the leakage current below subthreshold increases more than one order of magnitude during constant circuit stress at room temperature, for the thermal oxide it is quite constant, but at higher level for higher temperatures.

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Boston, R., A. Bell, V. P. Ting, A. T. Rhead, T. Nakayama, C. F. J. Faul e S. R. Hall. "Graphene oxide as a template for a complex functional oxide". CrystEngComm 17, n. 32 (2015): 6094–97. http://dx.doi.org/10.1039/c5ce00922g.

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Bai, Hui Ping, Fu Hui Wang e Yuan Qiang Tu. "The Electrochemical Behavior of the Rehealing Oxide Scales After Pitting Corrosion". Advanced Materials Research 476-478 (febbraio 2012): 1399–402. http://dx.doi.org/10.4028/www.scientific.net/amr.476-478.1399.

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The electrochemical behaviour of the rehealing oxide scales on the K52 nanocrystalline coatings had been studied by polarization curves. The results indicated that the oxide scales formed on the nano-coating exhibited rehealing ability after pitting corrosion, and the coating still had excellent corrosion resistance. The rehealing ability was enhanced with prolonged re-oxidation time. EDX analyses revealed that the oxide scales within the pits were composed of mixed-oxides (Cr2O3, Al2O3 and TiO2). The mixed-oxides were made up of two layers: the external oxide layer was composed of Cr2O3 and TiO2 and the internal oxide layer was Al2O3.

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Ye, Zhi Guo, Xian Liang Zhou, Hui Min Meng, Xiao Zhen Hua, Ying Hu Dong e Ai Hua Zou. "The Electrochemical Characterization of Electrochemically Synthesized MnO₂-Based Mixed Oxides for Supercapacitor Applications". Advanced Materials Research 287-290 (luglio 2011): 1290–98. http://dx.doi.org/10.4028/www.scientific.net/amr.287-290.1290.

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Nanostructured elements, including: manganese-molybdenum (Mn-Mo) oxide, manganese-molybdenum-tungsten (Mn-Mo-W) oxide, manganese-molybdenum-iron (Mn-Mo-Fe) oxide, manganese-molybdenum-cobalt (Mn-Mo-Co) oxide, manganese-vanadium-tungsten (Mn-V-W) oxide, manganese-vanadium-iron (Mn-V-Fe) oxide and manganese-iron (Mn-Fe) oxide, have been anodically deposited onto titanium substrates by employing an iridium dioxide interlayer (Ti/IrO2anode). The electrochemical characteristics of the resultant oxide deposits have been investigated by cyclic voltammetry (CV) in an aqueous 0.1 M Na2SO4solution. The voltammetric behaviors of the oxide deposits observed are significantly influenced by the doped elements. Molybdenum doping is found to be advantageous at improving the capacitance characteristics of anodically deposited manganese oxide. Comparatively, iron and vanadium doping are found to be unfavorable. The structure and crystallinity of these deposits have been identified by X-ray diffraction (XRD). The surface morphologies of these oxides were acquired from field emission scanning electron microscopes (FESEM). The high values of electrical parameters for the doped deposits are attributed to the net-like and sponge-like nanostructure, and low crystallinity of the doped manganese oxides. The deposit of Mn-Mo oxides exhibits an excellent capacitive-like behavior, possessing the maximum specific capacitance of 810 F g-1at a CV scan rate of 5 mV s-1in aqueous 0.1 M Na2SO4solution.

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T.Ch.Taghiyeva, T. Ch Taghiyeva. "X-RAY DIFFRACTION STUDY OF BINARY ZINC-OXIDE CATALYSTS". Azerbaijan Journal of Chemical News 04, n. 01 (30 maggio 2022): 60–64. http://dx.doi.org/10.32010/ajcn5012022-60.

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The phase composition of binary zinc-containing catalysts was studied by X-ray diffraction. It was found that the formation of two phases of the initial oxides is observed in all the studied catalytic systems. So, samples of the Zr-Zn-O catalytic system consist of phases of zirconium and zinc oxides, samples of the Ce-Zn-O catalytic system consist of phases of cerium and zinc oxides, while samples of the Mg-Zn-O catalytic system consist of phases of magnesium and zinc oxides. It has been established that the crystallinity of binary zinc-containing catalysts varies in the range from 70% to 89%. Keywords: X-ray phase analysis, binary catalysts, zinc oxide, cerium oxide, zirconium oxide, magnesium oxide

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Cole, Jordan, e Karen L. Syres. "Ionic liquids on oxide surfaces". Journal of Physics: Condensed Matter 34, n. 21 (25 marzo 2022): 213002. http://dx.doi.org/10.1088/1361-648x/ac5994.

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Abstract Ionic liquids (ILs) supported on oxide surfaces are being investigated for numerous applications including catalysis, batteries, capacitors, transistors, lubricants, solar cells, corrosion inhibitors, nanoparticle synthesis and biomedical applications. The study of ILs with oxide surfaces presents challenges both experimentally and computationally. The interaction between ILs and oxide surfaces can be rather complex, with defects in the oxide surface playing a key role in the adsorption behaviour and resulting electronic properties. The choice of the cation/anion pair is also important and can influence molecular ordering and electronic properties at the interface. These controllable interfacial behaviours make ionic liquid/oxide systems desirable for a number of different technological applications as well as being utilised for nanoparticle synthesis. This topical review aims to bring together recent experimental and theoretical work on the interaction of ILs with oxide surfaces, including TiO2, ZnO, Al2O3, SnO2 and transition metal oxides. It focusses on the behaviour of ILs at model single crystal surfaces, the interaction between ILs and nanoparticulate oxides, and their performance in prototype devices.

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Senzaki, Junji, Atsushi Shimozato, Kozutoshi Kajima, Keiko Aryoshi, Takahito Kojima, Shinsuke Harada, Yasunori Tanaka, Hiroaki Himi e Hajime Okumura. "Electrical Properties of MOS Structures on 4H-SiC (11-20) Face". Materials Science Forum 740-742 (gennaio 2013): 621–24. http://dx.doi.org/10.4028/www.scientific.net/msf.740-742.621.

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Threshold voltage (VTH) instability, channel mobility and oxide reliability have been investigated for meta-oxide-semiconductor (MOS) structures on 4H-SiC (11-20) face using various gate oxidation procedures. Channel mobility of n-channel MOSFET with a gate oxide by pyrogenic oxidation is higher than that by dilute-DRY oxidation followed by a nitrous oxide (N2O) post-oxidation annealing (POA). On the other hand, oxide reliability for the pyrogenic oxides is poor compared with the dilute-DRY/N2O oxides. A Hydrogen POA is effective in an improvement of channel mobility for both oxides, but causes a harmful effect on VTH stability. Temperature dependence of VTH instability indicates that MOS structure grown by dilute-DRY followed by N2O POA is suitable for a practical use of SiC MOS power devices.

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Kim, I. H., W. S. Kim e D. S. Rhee. "Photocatalytic Activity of Fe/Ti Mixed Oxide for Degrading Humic Acid in Water". Advanced Materials Research 717 (luglio 2013): 95–100. http://dx.doi.org/10.4028/www.scientific.net/amr.717.95.

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The comparative experiments for removing humic acid as environmental pollutant were conducted by adsorption on iron oxide, photooxidation in the presence of titanium dioxide catalyst and combined adsorption-photooxidation by iron-titanium mixed metal oxides, where all these active components were immobilized on polypropylene granules. The main purpose of the work was the combination of adsorption and photocatalytic oxidation processes to remove humic acid. The granules with iron-titanium mixed oxide for treating humic acid gave much better results with 1.2~3 times higher removal rates comparing to the other two single coated oxides at certain pH values. And the order of removal efficiency according to pH was the same as for single iron oxide-coated granules. The ratio 1:2 of iron oxide/titanium dioxide was found optimal for maximal decolorization of humic acid solution. The total organic carbon decrease of humic acid in each experiments, when it was pre-equilibrated with mixed oxides-coated granules in the dark for 30 min and without pre-equilibration, was very similar. The results suggested that the mechanism of humic acid removal may be not only a respectively combined adsorption and photooxidation by iron oxide and titanium oxides, but an enhanced photooxidation reaction as a result of concentrating humic acid on titanium oxide surface by iron oxide.

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29

Kajitani, Tsuyoshi, Yuzuru Miyazaki, Kei Hayashi, Kunio Yubuta, X. Y. Huang e W. Koshibae. "Thermoelectric Energy Conversion and Ceramic Thermoelectrics". Materials Science Forum 671 (gennaio 2011): 1–20. http://dx.doi.org/10.4028/www.scientific.net/msf.671.1.

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Abstract (sommario):

Oxide thermoelectrics are relatively new materials that are workable at temperatures in the range of 400K≤T≤1200K. There are several types of thermoelectric oxide, namely, cobalt oxides (p-type semi-conductors), manganese oxides (n-type) and zinc oxides (n-type semi-conductors) for high temperature energy harvesting. The Seebeck coefficient of 3d metal oxide thermoelectrics is relatively high due to either high density of states at Fermi surfaces or spin entropy flow associated with the carrier flow. The spin entropy part dominates the Seebeck coefficient of 3d-metal oxides at temperatures above 300K. Introduction of impurity particles or quantum-well structures to enhance thermionic emission and energy filtering effects for the oxide semiconductors may lead to a significant improvement of thermoelectric performance.

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30

Cheung, Kin P. "On the “intrinsic” breakdown of thick gate oxide". Journal of Applied Physics 132, n. 14 (14 ottobre 2022): 144505. http://dx.doi.org/10.1063/5.0118081.

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Abstract (sommario):

The thick gate oxide breakdown mechanism has become an important topic again due to the rising demand for power electronics. The failure of the percolation model in explaining the observed Weibull shape factor, β, seriously hampers the establishment of thick gate oxide breakdown models and the ability to project reliability from measurement data. In this work, lifetime shortening by oxide defects is simulated to produce degraded breakdown distributions that match experimentally observed βs. The result shows that even a low density of defects with the right energy is enough to greatly degrade β for thick oxides. Strong area scaling for thin oxides counters this sensitivity to defects effectively and explains why the percolation model is successful in thin oxides but not in thick oxides. Only defects with the appropriate energy can degrade the breakdown distribution. The required energy is consistent with oxygen vacancy Eγ′ defect after capturing a hole and the concentration required is consistent with very high-quality oxide. This explains the consistent low β values for thick oxides universally reported in the literature.

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31

Lim, Way Foong, Zainovia Lockman e Kuan Yew Cheong. "Effects of Post-Deposition Annealing Time on Metal-Organic Decomposed Lanthanum Cerium Oxide Film Spin-Coated on Si Substrate". Advanced Materials Research 1024 (agosto 2014): 364–67. http://dx.doi.org/10.4028/www.scientific.net/amr.1024.364.

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Abstract (sommario):

Metal-oxide-semiconductor characteristics of MOD-derived lanthanum cerium oxide (LaxCeyOz) film deposited on n-type Si substrate have been studied. Post-deposition annealing of the oxide was performed in argon atmosphere for a dwell time, ranging from 15 to 120 min at a fixed temperature of 400°C. Results demonstrated presence of positively charged oxygen vacancies in all of the oxides post-deposition annealed for different dwell time. Acquisition of the lowest effective oxide charge as well as the lowest interface trap density and total interface trap density in oxide annealed for 120 min has led to the attainment of the highest breakdown voltage, surpassing other oxides.

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32

Gulkhan, Genjemuratova, e Jumabayeva Janna Mahmud kizi. "THE DISSOLUTION OF ANTIMONY OXIDES, AND LEAD AND OTHER RELATED METALS IN ALKALINE-AQUEOUS ORGANIC SOLUTIONS". International Journal of Pedagogics 03, n. 06 (1 giugno 2023): 35–38. http://dx.doi.org/10.37547/ijp/volume03issue06-10.

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Metal oxides such as antimony oxide and lead oxide can be dissolved in alkaline-aqueous organic solutions through various methods, including acid-base reactions, complexation, ion exchange, and redox reactions. These methods involve manipulating factors such as pH, temperature, type of solvent, concentration of metal oxide, and presence of other ions. By dissolving metal oxides, they can be extracted from various materials.

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33

Hanhela, PJ, e DB Paul. "Organic Curing Agents for Polysulfide Sealants. II. Additions of Thiols to Nitrile Oxides: Scope, Relative Reactivities and Application to the Cure of Polysulfide Sealants". Australian Journal of Chemistry 42, n. 8 (1989): 1257. http://dx.doi.org/10.1071/ch9891257.

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Efficient addition between various nitrile oxides and both short (C2) and long chain (C16) alkyl thiols , aliphatic dithiols and aryl thiols occurred rapidly at ambient temperature with the formation of thiohydroximic acid derivatives. Competitive experiments with bis( nitrile oxides) showed that for terephthalonitrile oxide the second addition proceeded more readily than the first whereas with anthracene-9,l0-bis(carbonitrile oxide) elevated temperatures were needed to obtain the diadduct. Relative reactivities of a number of thiols with nitrile oxides were also determined spectroscopically . Reaction between prop-2-ene-1-thiol and p-nitrobenzonitrile oxide afforded products resulting from both cycloaddition and 1,3-addition with the latter predominating. The polysulfide prepolymer LP-2 was cured effectively at ambient temperatures by both terephthalonitrile oxide and 4,4'-sulfonylbisbenzonitrile dioxide at CNO to SH ratios of 1.5 and higher giving tack-free products within 0.5 h and 90% cure in under 4 h. For the less highly cross-linked LP-32-based sealants, curing was a little slower. Unreinforced sealants produced in this manner were firm elastomers with hardness of 35-40 (Rex A). The naphthalenebis (carbonitrile oxides) afforded softer products while anthracene-9,10- bis(carbonitrile oxide) was ineffective. One-part formulations involving in situ generation of nitrile oxide from hydroximoyl chlorides and barium hydroxide (formed by action of water vapour on barium oxide) were also produced.

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34

Suchikova, Y. O., I. T. Bogdanov e S. S. Kovachov. "Oxide crystals on the surface of porous indium phosphide". Archives of Materials Science and Engineering 2, n. 98 (1 agosto 2019): 49–56. http://dx.doi.org/10.5604/01.3001.0013.4606.

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Abstract (sommario):

Purpose: f this paper is to is to establish the patterns of oxide formation on the surface of indium phosphide during electrochemical etching of mono-InP. Design/methodology/approach: A porous surface was formed with the anode electrolytic etching. Morphology of the surface was studied with the help of scanning electron microscope JSM-6490. The analysis of chemical composition of porous surface of samples was also performed. Findings: It was shown that during the electrochemical etching of indium phosphide, oxide films and crystallites form on the surface. It has been established that crystalline oxides are formed mainly on the surface of n-type indium phosphide. Continuous oxide films are predominantly formed on the surface of p-InP. Research limitations/implications: The research was carried out for indium phosphide samples synthesized in the solution of hydrofluoric acid, though, carrying out of similar experiments for crystalline oxides on the surface of porous indium phosphide obtained in other conditions, is necessary. Practical implications: The study of oxide crystals on the surface of porous indium phosphide has great practical importance since it is the reproducibility of experimental results that is the main problem of modern materials science, the more nanoengineering. Oxides can significantly affect the properties of materials. On the one hand, oxides significantly affect the recombination properties of materials, this can impair the operation of semiconductor devices. On the other hand, oxide films can serve as a passivating coating for the surface of a porous semiconductor. Such an oxide property will be useful for the practical application of nanostructured indium phosphide. Therefore, questions of the conditions for the formation of semiconductor intrinsic oxides, their structure, and chemical composition, and also the effect of oxides on the physical and technical characteristics of materials are important. Originality/value: The patterns of oxide formation on the surface of indium phosphide during electrochemical etching are investigated in this work. It is shown for the first time that the structure of an oxide depends on the orientation of the surface of the semiconductor. It was shown that continuous oxide films are formed on the surface of p-InP, and oxide crystalline clusters are formed on the surface of n-InP.

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35

Yang, Gene, Wonsang Jung, Sung-Jin Ahn e Dongkyu Lee. "Controlling the Oxygen Electrocatalysis on Perovskite and Layered Oxide Thin Films for Solid Oxide Fuel Cell Cathodes". Applied Sciences 9, n. 5 (12 marzo 2019): 1030. http://dx.doi.org/10.3390/app9051030.

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Abstract (sommario):

Achieving the fast oxygen reduction reaction (ORR) kinetics at the cathode of solid oxide fuel cells (SOFCs) is indispensable to enhance the efficiency of SOFCs at intermediate temperatures. Mixed ionic and electronic conducting (MIEC) oxides such as ABO3 perovskites and Ruddlesden-Popper (RP) oxides (A2BO4) have been widely used as promising cathode materials owing to their attractive physicochemical properties. In particular, oxides in forms of thin films and heterostructures have enabled significant enhancement in the ORR activity. Therefore, we aim to give a comprehensive overview on the recent development of thin film cathodes of SOFCs. We discuss important advances in ABO3 and RP oxide thin film cathodes for SOFCs. Our attention is also paid to the influence of oxide heterostructure interfaces on the ORR activity of SOFC cathodes.

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36

Baiutti, Federico, Georg Christiani e Gennady Logvenov. "Towards precise defect control in layered oxide structures by using oxide molecular beam epitaxy". Beilstein Journal of Nanotechnology 5 (8 maggio 2014): 596–602. http://dx.doi.org/10.3762/bjnano.5.70.

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Abstract (sommario):

In this paper we present the atomic-layer-by-layer oxide molecular beam epitaxy (ALL-oxide MBE) which has been recently installed in the Max-Planck Institute for Solid State Research and we report on its present status, providing some examples that demonstrate its successful application in the synthesis of different layered oxides, with particular reference to superconducting La2CuO4 and insulator-to-metal La2− x Sr x NiO4. We briefly review the ALL-oxide MBE technique and its unique capabilities in the deposition of atomically smooth single-crystal thin films of various complex oxides, artificial compounds and heterostructures, introducing our goal of pursuing a deep investigation of such systems with particular emphasis on structural defects, with the aim of tailoring their functional properties by precise defects control.

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37

Gazda, M., P. Jasinski, B. Kusz, B. Bochentyn, K. Gdula-Kasica, T. Lendze, W. Lewandowska-Iwaniak, A. Mielewczyk-Gryn e S. Molin. "Perovskites in Solid Oxide Fuel Cells". Solid State Phenomena 183 (dicembre 2011): 65–70. http://dx.doi.org/10.4028/www.scientific.net/ssp.183.65.

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Perovskite oxides comprise large families among the structures of oxide compounds, and several perovskite-related structures are also known. Because of their diversity in chemical composition, properties and high chemical stability, perovskite oxides are widely used for preparing solid oxide fuel cell (SOFC) components. In this work a few examples of perovskite cathode and anode materials and their necessary modifications were shortly reviewed. In particular, nickel-substituted lanthanum ferrite and iron-substituted strontium titanate as cathode materials as well as niobium-doped strontium titanate, as anode material, are described. Electrodes based on the modified perovskite oxides are very promising SOFC components.

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38

Ibrahim, Suriani, Tawatchai Charinpanitkul, Eiry Kobatake e Mana Sriyudthsak. "Nanowires Nickel Oxide and Nanospherical Manganese Oxide Synthesized via Low Temperature Hydrothermal Technique for Hydrogen Peroxide Sensor". Journal of Chemistry 2016 (2016): 1–6. http://dx.doi.org/10.1155/2016/9138961.

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Binary catalyst nickel oxides (NiO) and manganese oxides (MnO) were prepared individually via hydrothermal route. The catalysts were characterized by scanning electron microscope (SEM), Brunauer-Emmett-Teller (BET) analysis, cyclic voltammetry (CV), and amperometry. Morphology studies revealed physical structure of nanowires nickel oxide and spherical manganese oxide with estimated length of 0.3–2.3 μm and diameter of 0.2–0.8 μm, respectively. Surface areas obtained for nickel oxide and manganese oxide were 68.9 m2 g−1and 45.2 m2 g−1, respectively. Cyclic voltammetry exhibits electrochemical responses corresponding to the electrode surfaces. The linear responses of the binary catalyst modified gold electrodes with NiO-MnO were observed in the concentration range from 31.8 μM to 0.5 mM with the detection limit of 62.5 μM.

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39

Usoltseva, Natalya, Valery Korobochkin, Alesya S. Dolinina e Alexander M. Ustyugov. "Infrared Spectra Investigation of CuO-Al₂O₃ Precursors Produced by Electrochemical Oxidation of Copper and Aluminum Using Alternating Current". Key Engineering Materials 712 (settembre 2016): 65–70. http://dx.doi.org/10.4028/www.scientific.net/kem.712.65.

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Abstract (sommario):

Joint electrochemical oxidation of copper and aluminum using alternating current (AC) was performed. The electrolysis products were dried on air (method carbonate) and at the residual pressure of 3-5 kPa (oxide method). Cu-Al layered double hydroxide (Cu-Al/LDH) are formed at air carbonization. Oxide method saves copper (I) oxide. Heat treatment causes the decomposition of LDH to CuO and Al2O3 as well as Cu2O oxidation to CuO. Copper-aluminum spinel (CuAl2O4) is the product of solid-phase interaction of copper and aluminum oxides. Infrared spectra revealed that oxide method provides the boehmite dehydration and metal oxides interaction at lower temperature despite the fact that the poorly crystallized copper (II) oxide is formed at LDH decomposition.

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40

Samin, Samin, Suyanti Suyanti, Susanna Tuning Sunanti e Wisnu Ari Adi. "Synthesis and Certification of Lanthanum Oxide Extracted from Monazite Sand". Indonesian Journal of Chemistry 20, n. 6 (5 ottobre 2020): 1213. http://dx.doi.org/10.22146/ijc.44327.

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Abstract (sommario):

Synthesis and certification of lanthanum oxide extracted from monazite sand have been carried out. This research aimed to increase the added value of monazite sand and obtain the lanthanum oxide in-house certified reference material (CRM). Synthesis of lanthanum oxide consists of several stages, namely: monazite sand digestion, rare-earth elements hydroxide [REE(OH)3] precipitation, Ce separation, Nd separation, lanthanum oxalate precipitation, and calcination. Certification of lanthanum oxide was carried out by determining the average concentration of the oxides and its uncertainty from the seven accredited laboratories by the ISO 35-2006 statistical method. Two other minerals in the lanthanum oxide analyzed by the XRD method were cerium hydroxide [Ce(OH)3] and neodymium yttrium oxide fluoride (Nd2Y2O3F16). Lanthanum oxide certified contains ten oxides, with the two highest concentrations of La2O3 (91.662 ± 0.007)% and Nd2O3 (3.949 ± 0.002)%. Lanthanum oxide has met the qualification in-house CRM since it contained water less than 1%, was homogeneous, stable, and certified. La2O3 concentration in the lanthanum oxide in-house CRM from CSAT-BATAN, Indonesia was not significantly different in comparison to that from the Department of Chemical Engineering, Srinakharinwirot University, Thailand. Lanthanum oxide extracted from monazite sand can be used as reference material in determining the lanthanum oxide quality from the pilot plant process.

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41

JIANG, ZHI, HAIRONG ZHANG, ZHONGPENG WANG, MINGXIA CHEN e WENFENG SHANGGUAN. "SIMULTANEOUSLY CATALYTIC REMOVAL OF NOx AND SOOT ON RARE EARTH ELEMENT OXIDE LOADED WITH POTASSIUM AND TRANSITION NANOSIZED METAL OXIDES". Nano 03, n. 04 (agosto 2008): 239–44. http://dx.doi.org/10.1142/s1793292008001088.

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Abstract (sommario):

The simultaneous catalytic removal of NO x and soot over the rare earth element (REE) oxide-based mixture oxides loaded with potassium and transition nanosized metal oxide (designated as M/K/REE oxide) was investigated by using temperature-programmed reaction (TPR). The influence of the type of REE oxides together with the type and amount of transitional metal oxides on the catalytic removal activity was discussed. K / Nd 2 O 3 was found to be the most active oxide among the REE oxides to simultaneous remove the NO x and soot under lean conditions. Chromium oxide was more active than the other transition metal oxides on enhancing the activity of soot oxidation of Nd 2 O 3 loaded with potassium. The optimum loading level of chromium was about 10 wt%, with ignition temperature at about 237°C and the conversion ratio NO → N 2 about 24.1%. The Mn -loading on K / Nd 2 O 3 resulted in the biggest conversion efficiency of NO to N 2 at about 30.2%. The increasing catalytic reaction of NO x–soot activities is attributed to the formation of complex crystalline phase in the catalyst together with the improving contacting between catalysts and soot.

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42

Szpunar, Jerzy A., e Bae Kyun Kim. "High Temperature Oxidation of Steel; New Description of Structure and Properties of Oxide". Materials Science Forum 539-543 (marzo 2007): 223–27. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.223.

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The quality of steel sheets is strongly affected by the surface defects that can be generated during hot rolling and are often related to scales removal operation. These defects are related to rather complex high temperature oxidation processes. In order to reduce an occurrence of the defects, it is necessary to understand better the formation of iron oxides during high temperature oxidation, the structure of the interfaces with the substrate and between different oxide phases. However, due to the lack of good experimental research tools details of iron oxide microstructures were not investigated. Conventional methods, such as backscattered electron images or fractography can only provide general characteristics of microstructures like grain morphology and grain size. In this paper the microstructure, phase distribution and texture in oxide formed during high temperature oxidation of iron and low carbon steels are investigated. The oxide microstructures are characterized by orientation imaging microscopy (OIM) on the cross-sectional area of the oxide layers. It is demonstrated that OIM using electron backscattered diffraction (EBSD) techniques, can be used to distinguish grains having different phase composition and orientation and can become invaluable tool for visualizing the oxide microstructure, texture and also can be used to study oxide defects. The three different iron oxides phases can be distinguished and the characteristics of oxides with different oxidation histories compared The characteristics of high temperature oxidation microstructure of iron are presented with description of iron oxide defects and cracking as well as the illustration of the interfacial microstructure between the layered iron oxides.

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43

Peng, Xiangyu, e Hongna Mu. "A Study on the Temporal and Spatial Changes of Nitrogen Oxides in the Southwest Corner of Jingzhou City Wall". Journal of Global Humanities and Social Sciences 5, n. 3 (25 marzo 2024): 120–25. http://dx.doi.org/10.61360/bonighss242015970303.

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Abstract (sommario):

With the growth of people's consumption capacity, the production and consumption of energy are rapidly increasing every year, and the emissions of nitrogen oxides are also increasing. Nitrogen oxides include many types of compounds, such as nitric oxide (NO), nitrogen dioxide (NO2), nitrous oxide (N2O), etc. Except for nitrogen dioxide, the properties of other nitrogen oxides are extremely unstable. Therefore, in the actual atmosphere, nitric oxide (NO) and nitrogen dioxide (NO2) are usually collectively referred to as nitrogen oxides (NOx). This article measured and compared the nitrogen oxide concentration and other meteorological indicators in the public, commercial, and civilian areas at the southwest corner of the city wall in Jingzhou City in March and April 2022. The following conclusions were drawn: the mass concentration of nitrogen oxide pollutants was highest around noon and evening, and the concentration was relatively small before and after sunrise and afternoon, with a "double peak and double valley" distribution. The nitrogen oxide concentration began to decrease at night and reached the first valley in the early morning, then it gradually rises, reaching its peak around 8:00 and then showing a downward trend. A second trough will appear around 13:00, followed by a continuous increase in concentration, and finally a small peak will appear at 18:00.

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44

Moonngam, Suphitcha, Pranpreeya Wangjina, Ekkarut Viyanit e Chaiyasit Banjongprasert. "Characterizing Oxide Inclusions in Welded Lean Duplex Stainless Steels and Their Influence on Impact Toughness". Materials 16, n. 5 (25 febbraio 2023): 1921. http://dx.doi.org/10.3390/ma16051921.

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Abstract (sommario):

In newly developed 2101 lean duplex stainless steel, oxide inclusions have been detected on welded metal zones after subjecting them to flux-cored arc welding with an E2209T1-1 flux-cored filler metal. These oxide inclusions directly affect mechanical properties of the welded metal. Hence, a correlation requiring validation has been proposed between oxide inclusions and mechanical impact toughness. Accordingly, this study employed scanning electron and high-resolution transmission electron microscopy to assess the correlation between oxide inclusions and mechanical impact toughness. Investigations revealed that the spherical oxide inclusions comprised a mixture of oxides in the ferrite matrix phase and were close to intragranular austenite. The oxide inclusions observed were titanium- and silicon-rich oxides with amorphous structures, MnO with a cubic structure, and TiO2 with an orthorhombic/tetragonal structure, derived from the deoxidation of the filler metal/consumable electrodes. We also observed that the type of oxide inclusions had no strong effect on absorbed energy and no crack initiation occurred near them.

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45

Awaluddin, Amir, Riska Anggraini, Siti Saidah Siregar, Muhdarina e Prasetya. "A one-pot synthesis of Fe-doped cryptomelane type octahedral molecular sieve manganese oxide for degradation of methylene blue dye". MATEC Web of Conferences 276 (2019): 06005. http://dx.doi.org/10.1051/matecconf/201927606005.

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The Fe-doped octahedral molecular sieve manganese oxides have been successfully synthesized by one-pot synthesis of the reaction between KMnO4 and glucose using sol-gel methods. The oxide products are then characterized by various techniques such as X-ray diffraction, scanning electron microscopy, atomic absorption spectroscopy and average oxidation state (AOS) of manganese in manganese oxides. The as-synthesized manganese oxide and Fe-doped manganese oxides are used as catalysts for the degradation of methylene blue dye using hydrogen peroxide as oxidants. The results indicated that the Fe-doped manganese oxide catalyst displayed much enhanced catalytic activities compared to undoped manganese oxide for methylene blue degradation. The differences in catalytic activities have been correlated with the difference in surface properties and crystallinity.

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46

Ohtsuka, Toshiaki. "Growth of passive oxide films on iron and titanium under non-stationary state". Corrosion Reviews 36, n. 1 (23 febbraio 2018): 87–104. http://dx.doi.org/10.1515/corrrev-2017-0051.

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AbstractGrowth of passive oxides on iron and titanium under the non-stationary state was studied during constant current density (CD) oxidation and potential sweep oxidation. Increase and decrease of the thickness of the passive oxide film were determined from the relation between dissolution and growth CDs. By using rotating Fe disc-Pt ring electrode, the CDs of the dissolution from the oxide to solution and the growth of the passive oxide on iron were simultaneously measured. From the ratio of the growth CD to the dissolution CD and the pH dependence of the growth CD, a possible mechanism was discussed. Next, the growth of passive oxides on iron in pH 8.4 borate solution and on titanium in 0.1 m sulfuric acid solution during the potential sweep oxidation was examined by using three-parameter ellipsometry. Oxide growth was initially delayed when the sweep in the positive direction was started, and then the oxide film linearly grew with the potential increase. It was found that the oxide growth rate influenced the properties of the oxide film. The electric field in the oxide film during the non-stationary growth was discussed, concerned with the CD of the oxide film formation.

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47

Bulyarskiy S. V., Gusarov G. G., Dudin A. A., Koiva D. A. e Litvinova K. I. "Diagnosis of the technology of titanium and hafnium oxides by luminescence methods". Optics and Spectroscopy 131, n. 1 (2023): 23. http://dx.doi.org/10.21883/eos.2023.01.55512.4086-22.

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The article shows the role of oxygen vacancies in the formation of luminescence bands of titanium and hafnium oxides, and also demonstrates the relationship between the intensity of luminescence bands and the conditions for the synthesis of films of these materials. It is concluded that photoluminescence is a very sensitive method for diagnosing the composition of oxides. Luminescence bands at 2.45 eV in titanium oxide and 2.91 eV in hafnium oxide make it possible to analyze the change in the film composition under various technological conditions of their production. Keywords: oxygen vacancies, titanium oxide, hafnium oxide, photoluminescence.

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48

DeForest, Tinsley Elizabeth, Shekhar Bhansali, Frank K. Urban, Dongmei Dong, Lihua Lou, Arvind Agarwal, Sofia Pinzon et al. "Exploring the Dielectric Properties of Lanthanide Oxide Thin Films". ECS Meeting Abstracts MA2023-02, n. 32 (22 dicembre 2023): 1582. http://dx.doi.org/10.1149/ma2023-02321582mtgabs.

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Abstract (sommario):

Lanthanide oxides play a crucial role in various applications, such as solid oxide fuel cells, catalysis, and electronics, and their dielectric properties are essential in determining their performance. Ellipsometry is a powerful technique that can provide high-precision information on the dielectric properties of lanthanide oxides. By determining parameters such as the refractive index, thickness, and extinction coefficient of lanthanide oxides, ellipsometry can aid in the design and optimization of lanthanide oxide-based devices and materials for various applications. Our research group is currently using ellipsometry (supported by other characterization techniques) to investigate the dielectric properties of lanthanide oxide thin films, aiming to obtain information about the optical constants, surface roughness, and thickness of the films. This research aims to provide insights into the fundamental properties of lanthanide oxide thin films. Our findings could contribute to the long-term development of more efficient lanthanide oxide-based materials. We present our current findings and discuss the future direction for continued efforts.

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49

Nelson, Yarrow M., Leonard W. Lion, William C. Ghiorse e Michael L. Shuler. "Production of Biogenic Mn Oxides by Leptothrix discophora SS-1 in a Chemically Defined Growth Medium and Evaluation of Their Pb Adsorption Characteristics". Applied and Environmental Microbiology 65, n. 1 (1999): 175–80. http://dx.doi.org/10.1128/aem.65.1.175-180.1999.

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Abstract (sommario):

Biogenic Mn oxides were produced by the bacterium Leptothrix discophora SS-1 (= ATCC 3182) in a chemically defined mineral salts medium, and the Pb binding and specific surface area of these oxides were characterized. Growth of SS-1 in the defined medium with pyruvate as a carbon and energy source required the addition of vitamin B12. Complete oxidation of Mn(II) within 60 h required the addition of ≥0.1 μM FeSO4. Pb adsorption isotherms were determined for the biogenic Mn oxides (and associated cells with their extracellular polymer) and compared to the Pb adsorption isotherms of cells and exopolymer alone, as well as to abiotic Mn oxides. The Pb adsorption to cells and exopolymer with biogenic Mn oxides (0.8 mmol of Mn per g) at pH 6.0 and 25°C was 2 orders of magnitude greater than the Pb adsorption to cells and exopolymer alone (on a dry weight basis). The Pb adsorption to the biogenic Mn oxide was two to five times greater than the Pb adsorption to a chemically precipitated abiotic Mn oxide and several orders of magnitude greater than the Pb adsorption to two commercially available crystalline MnO2 minerals. The N2Brunauer-Emmet-Teller specific surface areas of the biogenic Mn oxide and fresh Mn oxide precipitate (224 and 58 m2/g, respectively) were significantly greater than those of the commercial Mn oxide minerals (0.048 and 4.7 m2/g). The Pb adsorption capacity of the biogenic Mn oxide also exceeded that of a chemically precipitated colloidal hydrous Fe oxide under similar solution conditions. These results show that amorphous biogenic Mn oxides similar to those produced by SS-1 may play a significant role in the control of trace metal phase distribution in aquatic systems.

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50

Takagaki. "Rational Design of Metal Oxide Solid Acids for Sugar Conversion". Catalysts 9, n. 11 (29 ottobre 2019): 907. http://dx.doi.org/10.3390/catal9110907.

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Aqueous-phase acid-catalyzed reactions are essential for the conversion of cellulose-based biomass into chemicals. Brønsted acid and Lewis acid play important roles for these reactions, including hydrolysis of saccharides, isomerization and epimerization of aldoses, conversion of d-glucose into 5-hydroxymethylfurfural, cyclodehydration of sugar alcohols and conversion of trioses into lactic acid. A variety of metal oxide solid acids has been developed and applied for the conversion of sugars so far. The catalytic activity is mainly dependent on the structures and types of solid acids. Amorphous metal oxides possess coordinatively unsaturated metal sites that function as Lewis acid sites while some crystal metal oxides have strong Brønsted acid sites. This review introduces several types of metal oxide solid acids, such as layered metal oxides, metal oxide nanosheet aggregates, mesoporous metal oxides, amorphous metal oxides and supported metal oxides for sugar conversions.

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