Artículos de revistas: "Composite materials Cu/D"

1

Wang, Qing Yun, Wei Ping Shen y Ming Liang Ma. "Mean and Instantaneous Thermal Expansion of Uncoated and Ti Coated Diamond/Copper Composite Materials". Advanced Materials Research 702 (mayo de 2013): 202–6. http://dx.doi.org/10.4028/www.scientific.net/amr.702.202.

Texto completo

Resumen

Heat sink materials not only should have higher thermal conductivity, but also have smaller difference of thermal expansion with cooled material. diamond/copper composites were made by the powder metallurgy method. Vacuum slowly vapor deposition technique was employed to deposit a titanium film on diamond particles before mixing with Cu powder in order to improve the bonding strength between Cu and diamond particles during sintering. The thermal expansion of diamond/Cu d composite was measured in the temperature range from 50 to 600 °C. The results show that the titanium film on diamond improves the interfacial bonding and reduces the coefficient of thermal expansion (CTE) of Cu/diamond composites. The CTE of diamond/Cu composites decreases with increasing diamond volume fraction as the results of mixture rule and the intense restriction effect of diamond reinforcement on the copper matrix. The residual stresses and pores in the composites affect instantaneous thermal expansion of diamond/Cu composites.

Los estilos APA, Harvard, Vancouver, ISO, etc.

2

Sundaram, Rajyashree, Atsuko Sekiguchi, Guohai Chen, Don Futaba, Takeo Yamada, Ken Kokubo y Kenji Hata. "Influence of Carbon Nanotube Attributes on Carbon Nanotube/Cu Composite Electrical Performances". C 7, n.º 4 (15 de noviembre de 2021): 78. http://dx.doi.org/10.3390/c7040078.

Texto completo

Resumen

Carbon nanotube (CNT)/copper composites offer promise as lightweight temperature-stable electrical conductors for future electrical and electronic devices substituting copper. However, clarifying how constituent nanotube structures influence CNT/Cu electrical performances has remained a major research challenge. Here, we investigate the correlation between the CNT/Cu electrical performances and nanotube structure by preparing and characterizing composites containing nanotubes of different structural attributes. We prepared three types of composites—single-wall (SW)-CNT/Cu wires, SW-CNT/Cu pillars, and multi-wall (MW)-CNT/Cu wires. The composites were fabricated from the corresponding CNT templates by two-step Cu electrodeposition, which retains template nanotube attributes through the fabrication process. The nanotube characteristics (diameter, G/D, alignment, etc.) in each template as well as the internal structure and electrical performances of the corresponding composites were characterized. SW-CNT/Cu wires and pillars outperformed MW-CNT/Cu wires, showing ≈ 3× higher room-temperature four-probe conductivities (as high as 30–40% Cu-conductivity). SW-CNT/Cu also showed up to 4× lower temperature coefficients of resistances i.e., more temperature-stable conductivities than MW-CNT/Cu. Our results suggest that few-walled small-diameter nanotubes can contribute to superior temperature-stable CNT/Cu conductivities. Better CNT crystallinity (high G/D), fewer nanotube ends/junctions, and nanotube alignment may be additionally beneficial. We believe that these results contribute to strategies for improving CNT/Cu performances to enable the real-world application of these materials as Cu substitutes.

Los estilos APA, Harvard, Vancouver, ISO, etc.

3

Zhang, Dan-dan y Zai-ji Zhan. "Experimental investigation of interfaces in graphene materials/copper composites from a new perspective". RSC Advances 6, n.º 57 (2016): 52219–26. http://dx.doi.org/10.1039/c6ra07606h.

Texto completo

Resumen

The interface microstructure between the constituent phases in graphene/Cu composites, namely graphene plane–Cu (D_p) and graphene edges–Cu (D_e), were observed for the first time from the two directions by means of transmission electron microscopy.

Los estilos APA, Harvard, Vancouver, ISO, etc.

4

Widiatmoko, Julian, Fanghui Jia y Zhengyi Jiang. "Al-Cu Composite’s Springback in Micro Deep Drawing". Journal of Engineering and Technological Sciences 55, n.º 4 (26 de octubre de 2023): 384–92. http://dx.doi.org/10.5614/j.eng.technol.sci.2023.55.4.3.

Texto completo

Resumen

With the recent technological trend of miniaturization in manufacturing industries, the rise of micro forming operations such as micro deep drawing (MDD) is inevitable. On the other hand, the need of more advanced materials is essential to accommodate various applications. However, a major problem are size effects that make micro scale operations challenging. One of the most important behaviors affected by size effects is the springback phenomenon, which is the tendency of a deformed material to go back to its original shape. Springback can affect dimensional accuracy, which is very important in micro products. Thus, this paper investigated the springback behavior of Al-Cu composite in MDD operations. Micro cups were fabricated from blank sheet specimens using an MDD apparatus with variation of annealing holding time. The springback values were measured and compared to each other. The results showed that different grain sizes lead to variation in the amount of springback. However, unlike in single-element materials, the amount of springback in Al-Cu composite is not only related to the thickness to grain size (t/d) ratio. Another factor, i.e., the existence of an interfacial region between layers, alters the mechanical behavior of the composite.

Los estilos APA, Harvard, Vancouver, ISO, etc.

5

Orii, Yuta, Masaki Kobayashi, Yuki Nagai, Kohei Atsumi, Daichi Tazaki, Satoshi Ehara y Takashiro Akitsu. "Anisotropic strain and Jahn-Teller effect of chiral complexes and metal oxides". Acta Crystallographica Section A Foundations and Advances 70, a1 (5 de agosto de 2014): C179. http://dx.doi.org/10.1107/s2053273314098209.

Texto completo

Resumen

For about a decade, we have systematically investigated thermally-accessible lattice strain and local pseudo Jahn-Teller distortion of [CuL2]3[M(CN)6]2·4H2O (L = (1R, 2R)-cyclohexanediamine; M = Cr, Co, and Fe). In mononuclear Cu(II) complexes, (pseudo) Jahn-Teller effect plays an important role in flexible distortion of crystal structures especially Cu(II) coordination environment. Beside Jahn-Teller distortion, we have dealt with some factors for example, metal substitution as bimetallic assemblies, chirality of ligands, and H/D isotope effect to vary intermolecular interaction and crystal packing. According to the course work using variable temperature PXRD, we have found that anisotropy of crystal strain distortion did not corporate with Jahn-Teller distortion around local coordination environment because of the discrepancy of the crystallographic axes and molecular alignment. In order to elucidate the anisotropic control of lattice strain and Jahn-Teller distortion closely, we have employed transition metal oxide with orthogonal or layered structures to prepare composite materials with the chiral metal complexes for discussion of thermally-accessible PXRD changes and IR shift due to adsorption. At first, we have employed chiral one-dimensional zig-zag Cu-Cr bimetallic assemblies and their oxides prepared by burining. Based on variable temperature XRD patterns, a linear correlation (lnK = a/T + b) of K (=d(T)-d(0)/d(T)) values, where d(T) and d(0) are spacing of lattice plane (d = nλ/(2sinθ)) at T K and 0 K (extrapolated), respectively, and its deviation from ideal correlation indicates degree of anisotropic lattice distortion of the composite materials. For example, we could observe LiMnO2, typical material of lithium ion battery, was enhanced anisotropic lattice strain along the b axis or the (011) plane added by [CuL2(H2O)2](NO3)2 complexes. Which may prevent from breaking down regular crystal structures during charge-discharge of secondary battery.

Los estilos APA, Harvard, Vancouver, ISO, etc.

6

Chow, G. M., T. Ambrose, John Q. Xiao, M. E. Twigg, S. Baral, A. M. Ervin, S. B. Qadri y C. R. Feng. "Chemical precipitation and properties of nanocrystalline FeCu alloy and composite powders". Nanostructured Materials 1, n.º 5 (septiembre de 1992): 361–68. http://dx.doi.org/10.1016/0965-9773(92)90086-d.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

7

Stando, Grzegorz Jan, Pyry-Mikko Hannula, Bogumiła Kumanek, Mari Lundström, Haitao Liu y Dawid Janas. "(Digital Presentation) Recovery of Copper from Wastewater By Electrodeposition Onto Nanocarbon Composites". ECS Meeting Abstracts MA2022-01, n.º 9 (7 de julio de 2022): 761. http://dx.doi.org/10.1149/ma2022-019761mtgabs.

Texto completo

Resumen

The connection of carbon nanostructures such as graphene or carbon nanotubes with other materials like metals [1] or polymers [2] is often beneficial. For example, composites consisting of copper and nanocarbon materials have improved electrical [1] and mechanical [3] properties due to the synergy effect. Unfortunately, the integration between copper and nanocarbon is not an easy task because of the “cuprophobic” nature of nanocarbon [4]. Recently, many methods have been developed to accomplish this challenge. Out of all available techniques, physical (casting, spark plasma sintering or metal spinning) and electrochemical [5] gained a considerable share of attention. In particular, electrodeposition is a commonly employed strategy to deposit copper onto nanocarbon electrodes. In this method, nanocarbon surface plays the role of working electrode, onto which copper ions are reduced, thereby creating a Cu coating on the surface. This study demonstrates the recovery of copper from industrial wastewater by thin films based on carbon nanotubes (CNTs). Such a substrate was found as an ideal surface for the electrodeposition of metallic particles. Single/multi-walled CNTs, oxidized CNTs, nitrogen-doped CNTs and graphene were combined to obtain nanocarbon-nanocarbon composite electrodes, which were then used as substrates in Cu electrodeposition [6]. To establish the coating process parameters, synthetic solution of CuSO4 was first used as a source of copper ions. Then, wastewater of complex composition was employed directly for the electrodeposition process. Besides the 40 ppm of Cu, the wastewater contained other elements like salts Fe, Mg, Al, Zn and As in much greater amounts. It was discovered that such nanocomposite materials may be an excellent substrate for electrochemical recovery of Cu also from such a problematic waste, while simultaneously giving a product of high added value. Interestingly, the product was free from other metals, and only copper was detected on the nanocarbon surface. After just 1-hour of electrodeposition at -0.1V vs. SCE, a nanocarbon-based composite evenly coated with Cu was manufactured. Thorough investigation of the microstructure, and chemical composition of the nanocomposites correlated with the properties of the Cu coated materials enabled us to deduce critical parameters needed to make the Cu coating process effective [7]. [1] C. Arnaud, F. Lecouturier, D. Mesguich, N. Ferreira, G. Chevallier, C. Estournès, A. Weibel, C. Laurent, High strength - High conductivity double-walled carbon nanotube - Copper composite wires, Carbon N. Y. 96 (2016) 212–215. doi:10.1016/j.carbon.2015.09.061. [2] S.N. Beesabathuni, J.G. Stockham, J.H. Kim, H.B. Lee, J.H. Chung, A.Q. Shen, Fabrication of conducting polyaniline microspheres using droplet microfluidics, RSC Adv. 3 (2013) 24423–24429. doi:10.1039/c3ra44808h. [3] R. Jiang, X. Zhou, Q. Fang, Z. Liu, Copper-graphene bulk composites with homogeneous graphene dispersion and enhanced mechanical properties, Mater. Sci. Eng. A. 654 (2016) 124–130. doi:10.1016/j.msea.2015.12.039. [4] D. Janas, B. Liszka, Copper matrix nanocomposites based on carbon nanotubes or graphene, Mater. Chem. Front. 2 (2018) 22–35. doi:10.1039/c7qm00316a. [5] A. Singh, T. Ram Prabhu, A.R. Sanjay, V. Koti, An Overview of Processing and Properties of CU/CNT Nano Composites, Mater. Today Proc. 4 (2017) 3872–3881. doi:10.1016/J.MATPR.2017.02.286. [6] D. Janas, M. Rdest, K.K.K. Koziol, Free-standing films from chirality-controlled carbon nanotubes, Mater. Des. 121 (2017) 119–125. doi:10.1016/j.matdes.2017.02.062. [7] G. Stando, P.-M. Hannula, B. Kumanek, M. Lundström, D. Janas, Copper recovery from industrial wastewater - Synergistic electrodeposition onto nanocarbon materials, Water Resour. Ind. 26 (2021) 100156. doi:10.1016/J.WRI.2021.100156. G.S. and P.S. would like to thank the Ministry of Science and Higher Education of Poland for financial support of research (under Diamond Grant, grant agreement 0036/DIA/201948). G.S. also would like to thank European Union for thanks for financing the costs of the conference (European Social Fund, grant nr POWR.03.05.00-00-Z305) and National Agency for Academic Exchange of Poland (under the Iwanowska program, grant agreement PPN/IWA/2019/1/00017/UO/00001) for financial support during the stay at the University of Pittsburgh in the USA. G.S. and H.L. acknowledge NSF (CBET-2028826) for partial support of this work. G. S. and D.J. acknowledge the National Agency for Academic Exchange of Poland (under the Academic International Partnerships program, grant agreement PPI/APM/2018/1/00004) for supporting training in the Aalto University. G.S, B.K. and D.J. would like to thank the National Centre for Research and Development, Poland (under the Leader program, grant agreement LIDER/0001/L-8/16/NCBR/2017).

Los estilos APA, Harvard, Vancouver, ISO, etc.

8

Zaporotskova, I. V., D. P. Radchenko, L. V. Kozitov, P. A. Zaporotskov y A. V. Popkova. "Theoretical studies of a metal composite based on a monolayer of pyrolyzed polyacrylonitrile containing paired metal atoms Cu—Co, Ni—Co, Ni—Cu, Ni—Fe and an amorphizing silicon additive". Izvestiya Vysshikh Uchebnykh Zavedenii. Materialy Elektronnoi Tekhniki = Materials of Electronics Engineering 23, n.º 3 (10 de noviembre de 2020): 196–202. http://dx.doi.org/10.17073/1609-3577-2020-3-196-202.

Texto completo

Resumen

An urgent problem of radio engineering and radioelectronics nowadays is the synthesis of composite materials with preset parameters that can be used as electronics engineering materials. Of special interest are MW range wide-band electromagnetic radiation absorbers. Special attention is paid to materials on the basis of ferromagnetic metals that are capable of effectively absorbing and reflecting incident waves and having a clear nanostructure. Development of nanocapsulated metals will allow controlling the parameters of newly designed materials. This is achieved with the use of polymer matrices, e.g. pyrolyzed polyacrylonitrile (PPAN). This work is a theoretical study of a PPAN monolayer model containing pairs of transition metal atoms iron, nickel and cobalt which possess ferromagnetic properties, in Fe–Co, Ni–Co and Fe–Ni combinations, with silicon amorphizing admixture. We studied the geometrical structure of the metal composite systems which are modeled as PPAN molecular clusters the centers of which are voided of six matrix material atoms, the resultant defects (the so-called pores) being filled with pairs of the metal atoms being studied. The metal containing monolayer proved to be distorted in comparison with the initially planar PPAN monolayer. We plotted single-electron spectra of the composite nanosystems and characterized their band gaps. The presence of metal atoms reduces the band gap of a metal composite as compared with pure PPAN. We determined the charges of the metals and found electron density transfer from metal atoms to their adjacent PPAN monolayer atoms. We calculated the average bond energy of the test metal composite systems and proved them to be stable. The studies involved the use of the density functional theory (DFT) method with the B3LYP functional and the 6-31G(d) basis.

Los estilos APA, Harvard, Vancouver, ISO, etc.

9

Wang, Wen-Min, Lu Zhang, Wen-Long Wang, Jin-Yi Huang, Qian-Yuan Wu y Jerry J. Wu. "Photocatalytic Degradation of 1,4-Dioxane by Heterostructured Bi2O3/Cu-MOF Composites". Catalysts 13, n.º 8 (15 de agosto de 2023): 1211. http://dx.doi.org/10.3390/catal13081211.

Texto completo

Resumen

Photocatalysts exhibiting high activity for the degradation of 1,4-dioxane (1,4-D) have been a subject of intense focus due to their high toxicity and challenging degradability. Bismuth oxide (Bi2O3) is recognized as an ideal photocatalyst; however, there have been limited studies on its effectiveness in 1,4-D degradation. It is crucial to address the issue of low photocatalytic efficiency attributed to the instability and easy recombination of photogenerated electrons and holes in Bi2O3 upon photoexcitation. In this study, Cu-MOF and oxygen vacancy were utilized to improve the 1,4-D photocatalytic degradation efficiency of Bi2O3 by preparing Bi2O3, Bi2O3/Cu-MOF, Bi2O3−x, and Bi2O3−x/Cu-MOF. The results revealed that the incorporation of Cu-MOF induced a larger specific surface area, a well-developed pore structure, and a smaller particle size in Bi2O3, facilitating enhanced visible light utilization and an improved photoelectron transfer rate, leading to the highest photocatalytic activity observed in Bi2O3/Cu-MOF. In addition, oxygen vacancies were found to negatively affect the photocatalytic activity of Bi2O3, mainly due to the transformation of the β-Bi2O3 crystalline phase into α-Bi2O3 caused by oxygen vacancies. Further, the synergistic effect of MOF and oxygen vacancies did not positively affect the photocatalytic activity of Bi2O3. Therefore, the construction of heterojunctions using Cu-MOF can significantly enhance the efficiency of degradation of 1,4-D, and Bi2O3/Cu-MOF appears to be a promising photocatalyst for 1,4-D degradation. This study opens new avenues for the design and optimization of advanced photocatalytic materials with improved efficiency for the treatment of recalcitrant organic pollutants.

Los estilos APA, Harvard, Vancouver, ISO, etc.

10

Ali, Amira H., Asmaa S. Hassan, Ashour M. Ahmed, Ahmed A. Abdel-Khaliek, Sawsan Abd El Khalik, Safaa M. Abass, Mohamed Shaban, Fatimah Mohammed Alzahrani y Mohamed Rabia. "Preparation and Characterization of Nanostructured Inorganic Copper Zinc Tin Sulfide-Delafossite Nano/Micro Composite as a Novel Photodetector with High Efficiency". Photonics 9, n.º 12 (14 de diciembre de 2022): 979. http://dx.doi.org/10.3390/photonics9120979.

Texto completo

Resumen

A novel photodetector, based on Cu2ZnSnS4, CZTS, is deposited on Cu/CuFeO2 for wavelength and light power intensity detection. The preparation of CuFeO2 is carried out by the direct combustion of Cu foil wetted with Fe(NO3)2 solution. The preparation of CZTS is carried out using the hydrothermal method, then it is dropped on CuFeO2 using the drop casting method at 70 °C. Various analyses are used to look at the chemical, morphological, and optical aspects of the Cu/CuFeO2/CZTS, such as UV–vis, SEM, TEM, selected-area electron diffraction, and XRD, in which all characteristic peaks are confirmed for the prepared materials. The Cu/CuFeO2/CZTS thin film’s SEM image has a homogeneous morphology, with particles that are around 350 nm in size, demonstrating a significant improvement in morphology over Cu/CuFeO2/CZTS thin film. The TEM analysis verified the nanostructured morphology of Cu/CuFeO2/CZTS. From XRD analysis of Cu/CuFeO2/CZTS, the high intensity of the generated peaks indexed to hexagonal (2H) CuFeO2 and kesterite CZTS crystal structures revealed a compact highly crystal material. From optical analysis, CZTS, Cu/CuFeO2, and Cu/CuFeO2/CZTS thin films recoded band gaps of 1.49, 1.75, and 1.23 eV, respectively. According to the band gap measurements, the optical absorption of the Cu/CuFeO2/CZTS photodetector has clearly increased. The Cu/CuFeO2/CZTS as photodetector has a detectivity (D) and responsivity (R) of 1.7 × 1010 Jones and 127 mAW−1, respectively. Moreover, the external quantum efficiency (EQE) is 41.5% at 25 mW·cm−2 and 390 nm. Hence, the prepared Cu/CuFeO2/CZTS photodetector has a very high photoelectrical response, making it very promising as a broadband photodetector.

Los estilos APA, Harvard, Vancouver, ISO, etc.

11

Zhang, Yan, Ying Zhou, Lishou Ban, Tian Tang, Qian Liu, Xijun Liu y Jia He. "Cu–Ethanolamine Nanozymes Promote Urushiol Oxidation of Lacquer". Coatings 14, n.º 3 (12 de marzo de 2024): 332. http://dx.doi.org/10.3390/coatings14030332.

Texto completo

Resumen

In order to control the production cost of lacquer products, Cu–ethanolamine nanozymes were synthesized to simulate laccase to catalyze the oxidation and polymerization of urushiol. First-principles calculation results indicate that the D-band center of Cu center in the nanozymes was closer to the Fermi level than that of laccase, so Cu–ethanolamine was more conducive to the adsorption of substrate. The activation energy of Cu-ethanolamine catalyzed the oxidation of urushiol was significantly lower than that of laccase. Therefore, we inferred that the synthesized Cu–ethanolamine had a better catalytic effect on urushiol and was more conducive to paint film drying. By comprehensive comparison, the drying characteristics of the Cu–ethanolamine and raw lacquer with a 1:20 ratio are found to be closest to those of the raw lacquer, and the drying time is significantly shortened. The reaction results of the drying process performance test on the sample indicate that the composite lacquer can achieve the market-desired effect and performance requirements of the paint process.

Los estilos APA, Harvard, Vancouver, ISO, etc.

12

Rajendran, Sri Harini, Seung Jun Hwang y Jae Pil Jung. "Active Brazing of Alumina and Copper with Multicomponent Ag-Cu-Sn-Zr-Ti Filler". Metals 11, n.º 3 (19 de marzo de 2021): 509. http://dx.doi.org/10.3390/met11030509.

Texto completo

Resumen

The study was designed to investigate the synergic effect of Ti and Sn in the active metal brazing of Al2O3 ceramic to copper brazed, using the multicomponent Ag-Cu-Zr filler alloy. Numerous fine and hexagonal-shaped rod-like ternary intermetallic (Zr, Ti)5Sn3 phase (L/D = 5.1 ± 0.8, measured in microns) were found dispersed in the Ag-Cu matrix of Ag-18Cu-6Sn-3Zr-1Ti alloy, along with the ternary CuZrSn intermetallic phases. An approximate 15° reduction in contact angle and 3.1 °C reduction in melting point are observed upon the incorporation of Ti and Sn in Ag-18Cu-3Zr filler. Interestingly, the interface microstructure of Al2O3/Cu joints brazed by using Ag-18Cu-6Sn-3Zr-1Ti filler shows a double reaction layer: a discontinuous Ti-rich layer consisting of (Cu, Al)3(Ti, Zr)3O, TiO, and in-situ Cu-(Ti, Zr) precipitates on the Al2O3 side and continuous Zr-rich layer consisting of ZrO2 on the filler side. The shear strength achieved in Al2O3/Cu joints brazed with Ag-18Cu-6Sn-3Zr-1Ti filler is 31% higher, compared to the joints brazed with Ag-18Cu-6Sn-3Zr filler. Failure analysis reveals a composite fracture mode indicating a strong interface bonding in Al2O3/Ag-18Cu-6Sn-3Zr-1Ti filler/Cu joints. The findings will be helpful towards the development of high entropy brazing fillers in the future.

Los estilos APA, Harvard, Vancouver, ISO, etc.

13

Barbe, Julien, Anthony Valero, Emanuele Barborini y Guillaume Lamblin. "Synthesis of Graphene / Copper Composite Thin Foils As Innovative Anode Current Collectors for Lithium-Ion Batteries". ECS Meeting Abstracts MA2023-02, n.º 9 (22 de diciembre de 2023): 1004. http://dx.doi.org/10.1149/ma2023-0291004mtgabs.

Texto completo

Resumen

Lithium-ion batteries (LIB) are now considered as standard power storage units in laptops, mobile phones, and electric cars. Yet, they trigger important and constant R&D efforts to improve their energy density, lifespan, safety, and cost efficiency. Among LIB components, anodic copper current collector contributes to 8.1% of the total LIB weight [1]. In their ongoing quest to reduce the thickness of the anodic electrode foils, manufacturers face now a 6 µm thickness limitation due to mechanical issues (wrinkling and tearing) complicating their processing. In this context, using lighter materials with improved mechanical properties (with equal or improved thermal and electrical conductivity) compared to pristine copper is considered as an interesting solution to contribute to a further improvement of Lithium-Ion Batteries energy density. Owing to its high mechanical properties, high electrical and thermal conductivity, and low density [2], graphene and its derivates could be considered as promising materials to fabricate graphene / copper composites and achieve thinner / lighter current collectors. Such composites have already been successfully synthetised using copper electroplating with clear thermal and mechanical improvement [3]. The work to be presented in this talk will describe a new and simple route for the fabrication of graphene nanoplatelets (GNPs) or graphene oxide (GO) / copper composites consisting of : (i) the dispersion of graphene derivates in ethanol, (ii) their spraying onto Titanium substrate, (iii) a post electroplating on the sprayed graphene materials. In case of GNPs, a prior functionalization by polydopamine biopolymer is performed to increase their hydrophilicity and allow their dispersion. The polydopamine polymerization mechanism is known in literature to be complex and not extensively understood. The investigations done to understand the functionalization of GNPs by polydopamine using different techniques like Transmission Electron Microscopy (TEM) and X-ray Photoemission Spectroscopy (XPS) will be shared. Moreover, the use of Helium Ions Microscopy coupled with Secondary Ions Mass Spectrometer (HIM-SIMS) has been chosen as an original and powerful technique to further study the conformation of polydopamine onto GNPs. Finally, we will present the fabrication of thin graphene oxide copper composite foils and their characterization using Scanning Electron Microscope (SEM). A special focus will be given on the comprehension of copper nucleation behaviour on Graphene materials that remains not well studied. Electrochemical techniques such as impedance and current transient nucleation and growth analysis is currently under testing. [1] Zhu, P. Gastol, D. Marshall, J. Sommerville, R. Goodship, V. Kendrick, E. J Power Sources, 485, 229321 (2021) [2] Fatemeh Farjadian et al. Recent Developments in Graphene and Graphene Oxide: Properties, Synthesis, and Modifications: A Review 5,10200-10219, Chemistry Europe (2020) [3] Song, G. et al.. One-step synthesis of sandwich-type Cu/graphene/Cu ultrathin foil with enhanced property via electrochemical route. Materials and Design, 191, 108629. (2020)

Los estilos APA, Harvard, Vancouver, ISO, etc.

14

Alkallas, Fatemah H., Amira Ben Gouider Trabelsi, Tahani A. Alrebdi, Ashour M. Ahmed y Mohamed Rabia. "Development of a Highly Efficient Optoelectronic Device Based on CuFeO2/CuO/Cu Composite Nanomaterials". Materials 15, n.º 19 (2 de octubre de 2022): 6857. http://dx.doi.org/10.3390/ma15196857.

Texto completo

Resumen

Herein, an optoelectronic device synthesized from a CuFeO2/CuO/Cu nanocomposite was obtained through the direct combustion of Cu foil coated with Fe2O3 nanomaterials. The chemical, morphological, and optical properties of the nanocomposite were examined via different techniques, such as XRD, XPS, TEM, SEM, and UV/Vis spectrophotometer. The optical reflectance demonstrated a great enhancement in the CuFeO2 optical properties compared to CuO nanomaterials. Such enhancements were clearly distinguished through the bandgap values, which varied between 1.35 and 1.38 eV, respectively. The XRD and XPS analyses confirmed the chemical structure of the prepared materials. The produced current density (Jph) was studied in dark and light conditions, thereby confirming the obtained optoelectronic properties. The Jph dependency to monochromatic wavelength was also investigated. The Jph value was equal to 0.033 mA·cm−2 at 390 nm, which decreased to 0.031 mA·cm−2 at 508 nm, and then increased to 0.0315 mA·cm−2 at 636 nm. The light intensity effects were similarly inspected. The Jph values rose when the light intensities were augmented from 25 to 100 mW·cm−2 to reach 0.031 and 0.05 mA·cm−2, respectively. The photoresponsivity (R) and detectivity (D) values were found at 0.33 mA·W−1 and 7.36 × 1010 Jones at 390 nm. The produced values confirm the high light sensitivity of the prepared optoelectronic device in a broad optical region covering UV, Vis, and near IR, with high efficiency. Further works are currently being designed to develop a prototype of such an optoelectronic device so that it can be applied in industry.

Los estilos APA, Harvard, Vancouver, ISO, etc.

15

Ya, Bin, Yang Xu, Linggang Meng, Bingwen Zhou, Junfei Zhao, Xi Chen y Xingguo Zhang. "Fabrication of Copper Matrix Composites Reinforced with Carbon Nanotubes Using an Innovational Self-Reduction Molecular-Level-Mixing Method". Materials 15, n.º 18 (19 de septiembre de 2022): 6488. http://dx.doi.org/10.3390/ma15186488.

Texto completo

Resumen

An innovational self-reduction molecular-level-mixing method was proposed as a simplified manufacturing technique for the production of carbon nanotube copper matrix composites (CNT/Cu). Copper matrix composites reinforced with varying amounts of (0.1, 0.3, 0.5 and 0.7 wt%) carbon nanotubes were fabricated by using this method combined with hot-pressing sintering technology. The surface structure and elemental distribution during the preparation of CNT/Cu mixing powder were investigated. The microstructure and comprehensive properties of the CNT/Cu composites were examined by metallography, mechanical and electrical conductivity tests. The results revealed that the CNT/Cu could be produced by a high temperature reaction at 900 degrees under vacuum, during which the carbon atoms in the carbon nanotubes reduced the divalent copper on the surface to zero-valent copper monomers. The decrease in the ratio of D and G peaks on the Raman spectra indicated that the defective spots on the carbon nanotubes were wrapped and covered by the copper atoms after a self-reduction reaction. The prepared CNT/Cu powders were uniformly embedded in the grain boundaries of the copper matrix materials and effectively hindered the tensile fracture. The overall characteristics of the CNT/Cu composites steadily increased with increasing CNT until the maximum at 0.7 wt%. The performance was achieved with a hardness of 86.1 HV, an electrical conductivity of 81.8% IACS, and tensile strength of 227.5 MPa.

Los estilos APA, Harvard, Vancouver, ISO, etc.

16

Li, Zhenyu, Gengrui Zhao, Honggang Wang, Gui Gao, Shengsheng Chen, Dongya Yang, Yue Fan, Guowei Zhang y Hong Xu. "Microstructure and tribological behaviors of diffusion bonded powder sintered Cu–Sn based alloys". Materials Research Express 8, n.º 11 (1 de noviembre de 2021): 116505. http://dx.doi.org/10.1088/2053-1591/ac31ff.

Texto completo

Resumen

Abstract Owing to good self-lubricating performance, tin bronze is widely used in industrial fields. As tin bronze parts manufactured by powder metallurgy, their tribological performances are influenced by raw powder. In this work, four types of self-lubricating copper alloy composites (CuSn10 (D), CuSn10, CuSn10Pb10 (D) and CuSn10Pb10) were prepared by sintering completely alloyed powder and diffusion alloyed copper tin powder. The morphology, element distribution and microstructure of raw powder and their sintered Cu alloy composites were observed. The tribological properties of Cu alloys were investigated by block-ring friction test under different working conditions and their worn surface and wear debris were analyzed. The results show that the diffusion alloyed powder has an irregular dendritic morphology and its sintered Cu alloy is more likely to produce twin structure which enhances the hardness and the bearing capacity of the material. Compared with completely alloyed powder sintered CuSn10 sample, the wear rate of CuSn10 (D) sintered from diffusion alloyed powder was reduced by 83.96%, 74.39%, and 67.63% under three typical working conditions. Under dry friction conditions, the wear rate of CuSn10 (D) is reduced by 63.64% than CuSn10, and CuSn10Pb10 (D) is 25% lower than CuSn10Pb10. The investigation on the wear tracks and wear debris of Cu alloy composites showed that the diffusion alloyed powder sintered samples are inclined to form a more consecutive and integral third-body layer on wear tracks and which contributes to the better wear resistance.

Los estilos APA, Harvard, Vancouver, ISO, etc.

17

Elkatatny, Sally, Mohammed F. Alsharekh, Abdulrahman I. Alateyah, Samar El-Sanabary, Ahmed Nassef, Mokhtar Kamel, Majed O. Alawad, Amal BaQais, Waleed H. El-Garaihy y Hanan Kouta. "Optimizing the Powder Metallurgy Parameters to Enhance the Mechanical Properties of Al-4Cu/xAl2O3 Composites Using Machine Learning and Response Surface Approaches". Applied Sciences 13, n.º 13 (25 de junio de 2023): 7483. http://dx.doi.org/10.3390/app13137483.

Texto completo

Resumen

This study comprehensively investigates the impact of various parameters on aluminum matrix composites (AMCs) fabricated using the powder metallurgy (PM) technique. An Al-Cu matrix composite (2xxx series) was employed in the current study, and Al2O3 was used as a reinforcement. The performance evaluation of the Al-4Cu/Al2O3 composite involved analyzing the influence of the Al2O3 weight percent (wt. %), the height-to-diameter ratio (H/D) of the compacted samples, and the compaction pressure. Different concentrations of the Al2O3 reinforcement, namely 0%, 2.5%, 5.0%, 7.5%, and 10% by weight, were utilized, while the compaction process was conducted for one hour under varying pressures of 500, 600, 700, 800, and 900 MPa. The compacted Al-4Cu/Al2O3 composites were in the form of cylindrical discs with a fixed diameter of 20 mm and varying H/D ratios of 0.75, 1.0, 1.25, 1.5, and 2.0. Moreover, the machine learning (ML), design of experiment (DOE), response surface methodology (RSM), genetic algorithm (GA), and hybrid DOE-GA methodologies were utilized to thoroughly investigate the physical properties, such as the relative density (RD), as well as the mechanical properties, including the hardness distribution, fracture strain, yield strength, and compression strength. Subsequently, different statistical analysis approaches, including analysis of variance (ANOVA), 3D response surface plots, and ML approaches, were employed to predict the output responses and optimize the input variables. The optimal combination of variables that demonstrated significant improvements in the RD, fracture strain, hardness distribution, yield strength, and compression strength of the Al-4Cu/Al2O3 composite was determined using the RSM, GA, and hybrid DOE-GA approaches. Furthermore, the ML and RSM models were validated, and their accuracy was evaluated and compared, revealing close agreement with the experimental results.

Los estilos APA, Harvard, Vancouver, ISO, etc.

18

Yi, Jianya, Ruijie Hao, Qing Ji, Siman Guan, Zhijun Wang y Jianping Yin. "Study on the Equation of State and Jet Forming of 3D-Printed PLA and PLA-Cu Materials". Polymers 15, n.º 17 (28 de agosto de 2023): 3564. http://dx.doi.org/10.3390/polym15173564.

Texto completo

Resumen

In order to improve the research and development efficiency and quality of low-density liners in production and scientific research development, PLA and PLA-Cu composite liners were prepared based on 3D-printing technology. In this paper, the relationship between the shock wave velocity D and the particle velocity u of PLA and PLA-Cu materials was tested by a one-stage light gas gun experiment device, and then the Grüneisen equation of state parameters of the two materials was obtained by fitting. The forming process of the two jets was numerically simulated by using the equation of state. When combined with the pulsed X-ray shooting results of the jets, it was found that the jets of the two materials showed obvious characteristics of “expansion particle flow”, and the head of the PLA jet had a gasification phenomenon. The length of the PLA jet at 20 μs in the numerical simulation was 127.2 mm, and the average length of the PLA jet at 20 μs in the pulsed X-ray shooting experiment was 100.45 mm. The length of the PLA jet gasification part accounted for about 21% of the total length of the jet. The average velocity of the head of the PLA jet is 7798.35 m/s, and the average velocity of the head of the PLA-Cu jet is 8104.25 m/s. In this paper, 3D-printing technology is used to prepare the liner for the first time, aiming to open up a new preparation technology and provide a new material selection for low-density material liners.

Los estilos APA, Harvard, Vancouver, ISO, etc.

19

Priola, Emanuele, Ghodrat Mahmoudi, Jacopo Andreo y Antonio Frontera. "Unprecedented [d9]Cu⋯[d10]Au coinage bonding interactions in {Cu(NH3)4[Au(CN)2]}+[Au(CN)2]− salt". Chemical Communications 57, n.º 59 (2021): 7268–71. http://dx.doi.org/10.1039/d1cc02709c.

Texto completo

Resumen

The X-ray structure of the {Cu(NH₃)₄[Au(CN)₂]}⁺[Au(CN)₂]⁻ salt is reported showing an unprecedented [d⁹]Cu⋯[d¹⁰]Au coinage bond.

Los estilos APA, Harvard, Vancouver, ISO, etc.

20

Lu, Po-Wen, Chonlachat Jaihao, Li-Chern Pan, Po-Wei Tsai, Ching-Shuan Huang, Agnese Brangule, Aleksej Zarkov, Aivaras Kareiva, Hsin-Ta Wang y Jen-Chang Yang. "The Processing and Electrical Properties of Isotactic Polypropylene/Copper Nanowire Composites". Polymers 14, n.º 16 (18 de agosto de 2022): 3369. http://dx.doi.org/10.3390/polym14163369.

Texto completo

Resumen

Polypropylene (PP), a promising engineering thermoplastic, possesses the advantages of light weight, chemical resistance, and flexible processability, yet preserving insulative properties. For the rising demand for cost-effective electronic devices and system hardware protections, these applications require the proper conductive properties of PP, which can be easily modified. This study investigates the thermal and electrical properties of isotactic polypropylene/copper nanowires (i-PP/CuNWs). The CuNWs were harvested by chemical reduction of CuCl2 using a reducing agent of glucose, capping agent of hexadecylamine (HDA), and surfactant of PEG-7 glyceryl cocoate. Their morphology, light absorbance, and solution homogeneity were investigated by SEM, UV-visible spectrophotometry, and optical microscopy. The averaged diameters and the length of the CuNWs were 66.4 ± 16.1 nm and 32.4 ± 11.8 µm, respectively. The estimated aspect ratio (L/D, length-to-diameter) was 488 ± 215 which can be recognized as 1-D nanomaterials. Conductive i-PP/CuNWs composites were prepared by solution blending using p-xylene, then melt blending. The thermal analysis and morphology of CuNWs were characterized by DSC, polarized optical microscopy (POM), and SEM, respectively. The melting temperature decreased, but the crystallization temperature increasing of i-PP/CuNWs composites were observed when increasing the content of CuNWs by the melt blending process. The WAXD data reveal the coexistence of Cu2O and Cu in melt-blended i-PP/CuNWs composites. The fit of the electrical volume resistivity (ρ) with the modified power law equation: ρ = ρo (V − Vc)−t based on the percolation theory was used to find the percolation concentration. A low percolation threshold value of 0.237 vol% and high critical exponent t of 2.96 for i-PP/CuNWs composites were obtained. The volume resistivity for i-PP/CuNWs composite was 1.57 × 107 Ω-cm at 1 vol% of CuNWs as a potential candidate for future conductive materials.

Los estilos APA, Harvard, Vancouver, ISO, etc.

21

Tripathy, Debashis y S. Sampath. "(Digital Presentation) Earth-Abundant Copper-Based Electrode Materials for Li-Ion Storage". ECS Meeting Abstracts MA2022-01, n.º 2 (7 de julio de 2022): 286. http://dx.doi.org/10.1149/ma2022-012286mtgabs.

Texto completo

Resumen

Lithium-ion batteries (LIBs) find their use in almost all applications starting from electronic gadgets to grid energy storage and hybrid electric vehicles. In this direction, the development of high-capacity anodes is crucial to fulfil the increasing energy demand. To evaluate the Li+ ion storage performance, we have synthesized an earth-abundant copper-based electrode material, Cu3PS4, using the chemical vapor transport (CVT) method from the constituent elements Cu, P, and S in a 3:1:4 ratio. It has an enargite-type structure and has a layered-type morphology (Figure 1a). A high capacity of 970 mAh g-1 is obtained at 0.1 A g-1 current density. The electrode is amenable for high discharge rates up to 5 A g-1, and at a discharge rate of 1 A g-1, the cell can be cycled 5000 times with 90% capacity retention. The high electrochemical performance of the material is related to the conversion reaction as probed by in situ Raman spectroscopy (Figure 1b) and surface-controlled capacitive contribution due to the formation of a polymeric film over the electrode surface. A full cell with LiCoO2 cathode results in a large number of cycles with stable performance. Further improvement is achieved by forming a composite with an organic polymer, polybenzimidazole. The composite electrode delivers almost double the capacity of the pristine electrode. Other studies on the use of the electrode material to multivalent ion storage based on Mg2+, Zn2+, and Al3+ are in progress. Reference D. Tripathy and S. Sampath, J. Power Sources 2020, 478, 229066. Figure 1. (a) Unit cell structure and SEM image of Cu3PS4 and (b) in situ Raman spectra of the electrode after discharge. Figure 1

Los estilos APA, Harvard, Vancouver, ISO, etc.

22

Valero, Anthony, Julien Barbe, Emanuele Barborini y Guillaume Lamblin. "Development and Testing of Innovative Carbon Nanotubes/ Copper Composite Foils, Towards Lighter and Mechanically Improved Anode Current Collector for Lithium-Ion Batteries". ECS Meeting Abstracts MA2023-02, n.º 9 (22 de diciembre de 2023): 1002. http://dx.doi.org/10.1149/ma2023-0291002mtgabs.

Texto completo

Resumen

Up to now, copper is an essential material for lithium-ion battery industry as preferential candidate for anode current collectors due to its high conductivity, low price, and electrochemical stability in the working potential range of the anodic electroactive material. However, such component, accounting for 8.1% of the battery total weight, does not participate in any energy storage processes. [1] Thus, the trend is in this industry is to decrease the weight as well as the thickness of the collector foil to optimize the gravimetric energy of the whole lithium-ion battery system. It is therefore of interest to explore the development of lighter current collectors with equal/improved mechanical and electrical properties. Nanocarbon materials such as Multi-Wall Carbon Nanotubes (MWCNTs) and Single-Wall Carbon Nanotubes (SWCNTs) display a combination of performances, namely high electrical conductivity, low density and high mechanical stability, of a high interests to be combined with copper as innovative lightweight current collectors. Such nanocarbon/copper composite represents a valid alternative to foster the rapid change the battery technology is undergoing. In 2013, Subramaniam et al. [2] reported the fabrication of a Copper /Carbon nanotubes (Cu-CNTs) composites with a similar specific conductivity than that of copper and an ampacity increased by two orders of magnitude. Moreover, Arai et al. have shown, by Electrochemical impedance analysis, that MWCNTs additive in a copper matrix can serve as preferential electron conduction pathway inside a Lithium-ion battery anode. [3] Recently, a new promising and scalable way to fabricate nanocarbon/copper composite has been demonstrated by our team. The process involved the coating of MWCNTs by a dispersing agent, namely the Polydopamine biopolymer, their spraying, and finally the electrochemical plating of metallic copper inside the porosity of the MWCNTs network.[4] Following similar approach, the present work exhibits the fabrication of a free standing MWCNTs/ Copper composite current collector foil of a thickness of 9 µm, a value reaching the industrial standards required by the Lithium-ion battery market players for the next generation cells.[5] Scanning Electron Microscopy and Transmission Microscopy have been used to investigate the interaction between the copper matrix and the carbonaceous reinforcement additive. Figure 1. displays a cross section of nanocarbon/copper composite obtain via Focused Ion Beam slicing, where homogeneous mixing of copper and carbon phases down to nanoscale is highlighted. Such experiments contribute to the understanding of the copper nucleation mode on modified MWCNTs which remains insufficiently controlled to this day. Nanoindentation technique and electromechanical tensile testing bench were combined to study the mechanical properties of such material to be used under mechanical stress as battery collector. In contrary to conventional indentation technique where the mechanical properties of micro-size area are probed, indentation at nanoscale allow the probing of the local mechanical heterogeneity of a composite material. Using such technique, the fabricated self-standing nanocarbon/copper composite was shown to display average hardness and Young modulus close to those of pure carbon (3.5 GPa and 152 GPa respectively). Electrochemical performances of the composite as anode battery collector are under test into pouch and coin-cells battery architecture. The adhesion strength between the electrode slurry and the nanocomposite substrate material is expected to be reinforced by the addition of a nanocarbon. A focus was made on the impact of the use of this new collector material on the cycling stability of typical Lithium-ion battery commercial mixture. Preliminary results indicate that the Cu/MWCNT composite is a promising current collector material to withstand the expansion/contraction imposed by the working cycles of a rechargeable Lithium-ion battery. [1] Zhu, P. Gastol, D. Marshall, J. Sommerville, R. Goodship, V. Kendrick, E. J Power Sources, 485, 229321 (2021) [2] Subramaniam, C. Yamada, T. Kobashi, K. Sekiguchi, A. Futaba, Yumura, D. N. Hata, K. Nat Commun,4, 2202 (2013). [3] Shimizu, M. Ohnuki, T. Ogasawara, T. Banno, Arai, S., RSC Advances, 9(38), 21939-21945 (2019) [4] Duhain, A. Guillot, J. Lamblin, G. Lenoble, D., RSC Advances,11(63), 40159-40172 (2020) [5] Copper Foil Market, Straits Research, 9.5.2.3.(2022) Figure 1. Scanning Electron Microscopy imaging of the cross section of MWCNTs/Copper composite with a thickness lower than 3 µm – 7kV acceleration, 45° tilt. . Figure 1

Los estilos APA, Harvard, Vancouver, ISO, etc.

23

Sato, Ryuji, Takayuki Komatsu y Kazumasa Matusita. "Effect of Cu+ content on properties of Bi2Sr2CaCu2Ox glass". Journal of Non-Crystalline Solids 160, n.º 1-2 (julio de 1993): 180–82. http://dx.doi.org/10.1016/0022-3093(93)90299-d.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

24

Yu, D. P., W. Staiger y M. Kléman. "Transmission electron microscopy study of defects in AlLiCu quasicrystals". Journal of Non-Crystalline Solids 153-154 (febrero de 1993): 453–57. http://dx.doi.org/10.1016/0022-3093(93)90394-d.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

25

DAYA, Arun y Arputharaj SAMSON NESARAJ. "Review of materials, functional components, fabrication technologies and assembling characteristics for polymer electrolyte membrane fuel cells (PEMFCs) – An update". Journal of Metals, Materials and Minerals 33, n.º 4 (13 de diciembre de 2023): 1775. http://dx.doi.org/10.55713/jmmm.v33i4.1775.

Texto completo

Resumen

Fuel cells use electrochemical processes to transform the chemical energy of a fuel into electrical energy, which is a key enabler for the shift to an H2-based economy. Because of their high energy conversion efficiency and low pollution emissions, fuel cells with polymer electrolyte membranes (PEMFCs) are regarded as being in frontline of commercialization for the transportation and automotive industries. However, there are two major hurdles to their future commercialization: cost and durability, which promote basic study and development of their components. In this article, we reviewed the materials, functional components, fabrication technologies and assembling characteristics related to PEMFCs. Platinum's significance as a catalyst in PEMFC applications stems from the fact that it beats all other catalysts in three critical parts: stability, selectivity, and activity. In order to create Pt rich surfaces of NPs, Pt metal is alloyed with d-block metals like Cu, Ni, Fe, and Co. PEMFC development is inextricably tied to the benefits and drawbacks of the Nafion membrane under various operating circumstances. Nafion membrane has some drawbacks, including poor performance at high temperatures (over 90℃), low conductivity under low humidification, and high cost. As a result, a variety of nanoscale additives are frequently added to Nafion nanocomposites to enhance the material's properties under fuel cell working conditions. Fiber composite based bipolar plates can deliver best performance. The assembly of PEMFC based on strap approach is being explored. The applications of PEMFC are also projected.

Los estilos APA, Harvard, Vancouver, ISO, etc.

26

Wang, Chuantong, Peng Zhang, Jinjun Guo, Hongsen Zhang y Tingya Wang. "Effect of Municipal Solid Waste Incineration Ash on Microstructure and Hydration Mechanism of Geopolymer Composites". Buildings 12, n.º 6 (26 de mayo de 2022): 723. http://dx.doi.org/10.3390/buildings12060723.

Texto completo

Resumen

The geopolymerization process is an appropriate way of disposing of municipal solid waste incineration fly ash (MSWIFA), and possesses the advantages of immobilizing the heavy metals and making full use of its pozzolanic properties in manufacturing green, cementitious materials. In this study, coal fly ash (FA) and metakaolin (MK) were used to prepare a geopolymer composite, with MK partially replaced by different proportions of MSWIFA through the alkali-activation method. The microstructure and hydration mechanism of the geopolymer composites containing MSWIFA were investigated through mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), and Fourier transform-infrared spectroscopy (FT-IR) tests; and the immobilization effect of the geopolymer paste on heavy metal ions was explored through inductively coupled plasma-atomic emission spectrometry (ICP-AES). The MIP analysis showed that the addition of MFARR had an overall degrading effect on the pore structure of the matrix. When the content of MSWIFA reached the maximum of 35%, the porosity and average pore diameter increased by 25% and 16%, respectively, corresponding to the case without MSWIFA. However, the pore size distribution exhibited an improving trend when the MFARR was increased from 15% to 25%. The SEM images revealed that the integrity of the micromorphology of the geopolymer mortar became weaker after adding MSWIFA. When the MSWIFA content was increased to 35%, the microstructural compactness decreased and more pores and microcracks appeared in the matrix. The FT-IR pattern study suggested that all the geopolymer composites had a similar internal structure, consisting of O-H, C-O, Si-O-Si, and Si-O-Al. The main component of the geopolymer paste hydrated at 28 d remained dominated by calcium silica-aluminate (C-A-S-H), when the MSWIFA ranged from 0% to 35%. Finally, the ICP-AES results showed that the leaching concentrations of the geopolymer paste of J-40 at 28 d for Cd, Cr, Cu, Pb, and Zn met the requirements of Chinese standards.

Los estilos APA, Harvard, Vancouver, ISO, etc.

27

Pastuhov, P., O. Lavrenyuk, B. Mykhalitchko y V. Petrovskii. "FEATURES OF THE COPPER(II) CARBONATE INFLUENCE ON AN INFLAMMABILITY OF EPOXY-AMINE COMPOSITES". Fire Safety, n.º 33 (31 de diciembre de 2018): 73–78. http://dx.doi.org/10.32447/20786662.33.2018.10.

Texto completo

Resumen

Introduction. Inflammation susceptibility and the nature of combustion are one of the most important characteristics for the parametrization of the fire hazard of polymer materials. Because ignition is the occurrence process of the persistent flame near the surface of the material, which is preceded by the process of propagation of the flame front on its surface, the predisposition to ignition of the polymer materials plays an important role in the aspect of initiation of fires. A comparative evaluation of inflammation susceptibility of substances of different nature was carried out basing the determination of the ignition point and self-ignition point. Purpose. The work aims to determine the peculiarities of the influence of copper(II) carbonate on the increase of ignition point and self-ignition point of epoxy-amine composites. Metods. The experimental determination of the ignition point and self-ignition point was carried out according to all-Union State Standard 12.1.044-89 (4.7, 4.9 items). Toward this end, three samples of the test material were prepared with a weight of 3 g. Before testing, samples were conditioned in air. Results. Data on the effect of copper(II) carbonate on the value of ignition point and self-ignition point of the epoxy-amine composites indicate that the epoxy-amine-based composite, cured by the traditional amine hardener (PEPA), has lowest temperature of the ignition and self-ignition. The temperture values of ignition and self-ignition increase as the content of copper(II) carbonate increases in the composite, measuring up a maximum value at 80 g of CuCO3 per 100 g of binder. It is proved that the reason for the increase of the ignition temperature and self-ignition temperature of the modified epoxy-amine composites is the appearance of strong coordination bonds that are formed due to the chemical binding of the combustible polyethylenepolyamine with the non-combustible inorganic salt (with copper(II) carbonate). The measured values of the ignition point and self-ignition point of the amine hardener (PEPA) of the epoxy-diane oligomer indicate that it is able to ignite at temperature 136ºC, and self-ignite at temperature 393ºС. After forming the chelate complex, the coordinated PEPA turns into a practically non-combustible substance. Conclusion. Consequently, the main factor that affects to make difficulty of ignition of organic nitrogen-containing substances is the efficient chemical binding N atoms of the combustible amine molecules with d-metal atom of the non-combustible inorganic salt, which is accompanied by the formation of sufficiently strong coordination bonds of the Cu(ІІ)¬N type. The resistance to ignition of the modified polymeric composites will depend on the binding strength of the copper(II) salt with an amine hardener. The mechanism of the fire retardant influence of the d-metal salts on combustion of the epoxy-amine-based composites consists in this. So, copper(II) compounds, in particular copper(II) carbonate, can successfully be used as the fire retardant additives enabling of efficiently lowering the fire hazard of synthetic polymers based on epoxy-amine composites.

Los estilos APA, Harvard, Vancouver, ISO, etc.

28

Sun, Ping-Ping, Yu-Hang Zhang, Hongwei Shi y Fa-Nian Shi. "Study on the properties of Cu powder modified 3-D Co-MOF in electrode materials of lithium ion batteries". Journal of Solid State Chemistry 307 (marzo de 2022): 122740. http://dx.doi.org/10.1016/j.jssc.2021.122740.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

29

Li, Bing, Jun-Wei Zhao, Shou-Tian Zheng y Guo-Yu Yang. "Two Novel 1-D Organic–Inorganic Composite Phosphotungstates Constructed from [Ln(α-PW11O39)2]11− Units and [Cu(en)2]2+ Bridges (Ln = CeIII/ErIII)". Journal of Cluster Science 20, n.º 3 (4 de febrero de 2009): 503–13. http://dx.doi.org/10.1007/s10876-009-0235-8.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

30

Yoo, Ji-Eun y Young-Min Kang. "Fabrication and Electromagnetic wave absorption Properties of Co-Cu-substituted Ni-Zn Spinel Ferrite-epoxy Composites". Korean Journal of Metals and Materials 58, n.º 12 (5 de diciembre de 2020): 887–95. http://dx.doi.org/10.3365/kjmm.2020.58.12.887.

Texto completo

Resumen

Spinel ferrites (Ni0.5Zn0.5)1-x-yCoxCuyFe2O4, (x = 0 and y = 0, x = 0.2 and y = 0, x = 0.1 and y = 0.1, x = 0 and y = 0.2) were prepared by sol-gel method and post-annealed at 1100 oC. The grain growth of the sample is very sensitive to the Cu substitution y. The average grain size of the non-doped sample (x = 0, y = 0) was ~400 nm and it increased to ~3 μm at the sample with x = 0 and y = 0.2. The real and imaginary parts of permittivities (ε', ε") and permeabilities (μ', μ") were measured on the spinel ferrite powder-epoxy (10 wt%) composite samples by a network vector analyzer in the frequency range of 0.1 ≤ f ≤ 15 GHz. The μ' and μ" depend on Co substitution x and the ε' is sensitive to Cu doping y. Reflection loss (RL), which implies electromagnetic (EM) wave absorption properties, were analyzed based on the complex permeability, permittivity spectra. In the RL map plotted as functions of sample thickness (d) and frequency (f), the intensive EM absorbing area (RL < -30 dB) shifted to a high frequency region with increasing Co substitution. This can be attributed to a permeability spectra shift, due to the increase in ferromagnetic resonance frequency produced by the Co substitution. The samples with x = 0.1 and y = 0.1, x = 0.2 and y = 0 also exhibited a very broad-ranged EM wave absorbing performance with a d < 3 mm, indicated by RL < -10 dB being satisfied in the frequency range 7~14 GHz.

Los estilos APA, Harvard, Vancouver, ISO, etc.

31

Pustelny, Tadeusz Piotr. "Electroluminescent optical fiber sensor for detection of a high intensity electric field". Photonics Letters of Poland 12, n.º 1 (31 de marzo de 2020): 19. http://dx.doi.org/10.4302/plp.v12i1.980.

Texto completo

Resumen

On-line testing of high power electromagnetic devices is one of the most important problems of modern industrial metrology. In the paper, the results of experimental investigations of the electric field optical fiber sensor based on the electroluminescent phenomena are presented. The electro¬luminescent effect is observed in some composite semicon¬ductors, among others in zinc sulfide ZnS crystals. In our investigations, the used ZnS crystal was doped with copper Cu atoms as activators. The concentration of activator in the ZnS crystal was about 5.10-4 [g/g]. According to plans of investi¬gations of the elaborated electroluminescent sensor, the spectral properties as well as the intensity of light emission in sinusoidal alternating electric field were tested.Full Text: PDF References:K.T.V. Grattan, Fiber Optic Fluorescence Thermometry, Chapman and Hall, London, 1996 [CrossRef]K. Kyuma, S. Tai, T. Sawada, "Fiber-optic instrument for temperature measurement", J. Quntum. Electronics, 73(3), 1997 [CrossRef]A. Brief, J. Chem. Educ., 88(6), 731 (2011). [CrossRef]T. Pustelny, B. Pustelny, "Investigation of electroluminophores for their practical application in optical fibre sensor technology", Opto-Electronics Rev.,10(3), 193 (2002). [CrossRef]A.Wrzesinska, Photo- and electroluminophore, Wroclaw, PWN Press, 1988, (in polish) [DirectLink]K.A. Franz, W.G. Kehr, "Luminescent Materials", Ullmans Encyclopedie of Industral Chemistry, Wiley-VCH, Veinhen, 2008 [CrossRef]A.G. Milnes, Deep Impurities In Semiconductors, A Willey-Interscience Publication, Toronto, 1993 [DirectLink]M. Aven, J.S. Prener, Physics and Chemistry of II-VI Compounds, North-Holland Publishing Company - Amsterdam, 1993 [DirectLink]P.K. Cheo, Fiber Optics Devices and Systems, Prentice-Hall, 1985 [CrossRef]D. Randall, Fluorescence and Phosphorescence, Grown, Oxford, 2007. [CrossRef]M. Koen, Photoconductivity of Semiconductors, Edited by Parks, New York, 1996 [CrossRef]K.R. Murphy, C.A. Stedmon, Annal. Methods, 6(3), 658, (2014) [CrossRef]T. Pustelny, K. Barczak, K. Gut, J. Wojcik, "Special optical fiber type D applied in optical sensor of electric currents", Optica Applicata, 34(4), 531 (2004). [DirectLink]K. Barczak, T. Pustelny, D. Dorosz, J. Dorosz, "Polarization maintaining fibers for application in magnetic field measurements", Europ. Phys. Journal: S.T., 154, 11, (2008) [CrossRef]

Los estilos APA, Harvard, Vancouver, ISO, etc.

32

Kang, Kaijin, Fei Liang, Xianghe Meng, Jian Tang, Tixian Zeng, Mingjun Xia, Zheshuai Lin, Wenlong Yin y Kang Bin. "K4Cu3(C3N3O3)2X (X = Cl, Br): strong anisotropic layered semiconductors containing mixed p–p and d–p conjugated π-bonds". Chemical Communications 56, n.º 83 (2020): 12534–37. http://dx.doi.org/10.1039/d0cc04547k.

Texto completo

Resumen

Metal cyanurates K₄Cu₃(C₃N₃O₃)₂X (X = Cl, Br) containing π-conjugated anions are synthesized in flame-sealed silica tubes and they exhibit 2D graphene-like layered structures and intriguing semiconductor behaviors.

Los estilos APA, Harvard, Vancouver, ISO, etc.

33

Yamaguchi, Kazuki, Akari Takemura, Saki Furumoto, Ryohei Oka y Toshiyuki Masui. "Inorganic Green Pigments Based on LaSr2AlO5". Ceramics 6, n.º 4 (22 de noviembre de 2023): 2269–81. http://dx.doi.org/10.3390/ceramics6040138.

Texto completo

Resumen

La1.03Sr1.97Al0.97M0.03O5 (M = Fe, Co, Ni, and Cu) samples were synthesized using a citrate sol–gel method to develop a novel environmentally friendly inorganic green pigment. Among them, the Co-doped sample exhibited a vivid yellow, but not green. Then, (La0.94Ca0.06)Sr2(Al0.97Mn0.03)O5 was synthesized and characterized with respect to the crystal structure, optical properties, and color. The sample was obtained in a single-phase form and the lattice volume was smaller than that of the (La0.94Ca0.06)Sr2AlO5 sample, indicating that Mn ions in the lattice of the sample were pentavalent. The sample exhibited optical absorption at a wavelength below 400 nm and around 650 nm. These absorptions were attributed to the ligand, the metal charge transfer (LMCT), and d-d transitions of Mn5+. Because the green light corresponding to 500 to 560 nm was reflected strongly, the synthesized sample exhibited a bright green color. (La0.94Ca0.06)Sr2(Al0.97Mn0.03)O5 showed high brightness (L* = 50.1) and greenness (a* = −20.8), and these values were as high as those of the conventional green pigments such as chromium oxide and cobalt green. Therefore, the (La0.94Ca0.06)Sr2(Al0.97Mn0.03)O5 pigment is a potential candidate for a novel environmentally friendly inorganic green pigment.

Los estilos APA, Harvard, Vancouver, ISO, etc.

34

Zhang, Lingyun, Dajiang Mei, Yuanwang Wu, Chenfei Shen, Wenxin Hu, Lujia Zhang, Jinjin Li, Yuandong Wu y Xiao He. "Syntheses, structures, optical properties, and electronic structures of Ba6Cu2GSn4S16 (G = Fe, Ni) and Sr6D2FeSn4S16 (D = Cu, Ag)". Journal of Solid State Chemistry 272 (abril de 2019): 69–77. http://dx.doi.org/10.1016/j.jssc.2019.01.024.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

35

Rajeshwar, Krishnan. "(Invited) Solid-State Chemistry Meets Photoelectrochemistry: New Families of Ternary Oxides and Chalcogenides". ECS Meeting Abstracts MA2018-01, n.º 31 (13 de abril de 2018): 1844. http://dx.doi.org/10.1149/ma2018-01/31/1844.

Texto completo

Resumen

Even after ca. four decades of R&D effort, we still do not have a "magic bullet" inorganic semiconductor to photoelectrochemically generate fuels or chemicals from sunlight in a sustainable, efficient and environment-friendly manner. While it is unlikely that a single semiconductor candidate will emerge that simultaneously satisfies all the optical, electrical, surface chemical, and electrochemical prerequisites for efficient solar conversion, complex oxides or chalcogenides (or derivatives thereof, e.g., oxynitrides) do provide a versatile framework for rational design of the "perfect beast" in a chemical architectural sense. Ultimately two or more such semiconductor compositions can be combined in a composite design much like complementary functionalities are combined in photosynthetic assemblies in Nature. In such designs, the semiconductor(s) and the photoactive junction can even be separated from the electrolyte and the electrocatalyst component in a "buried junction" design. In this vein, the author's laboratory has been engaged in the development of time- and energy-efficient methods for synthesizing new families of photoelectrode or photocatalyst materials. In this particular talk, the author will provide first a context for the key role that solid-state chemistry paradigms and principles can play in photoelectrode designs for driving multi-electron processes typical of solar fuel generation. Two representative ternary semiconductor systems, namely, Cu-V-O and M-Ln-X (M = divalent metal, e.g., Ba, Ln = lanthanide element, e.g., Ce, and X = chalcogen, e.g., S) will be discussed in this talk.

Los estilos APA, Harvard, Vancouver, ISO, etc.

36

Paidpilli, Mahesh y Venkat Selvamanickam. "Development of RE-Ba-Cu-O superconductors in the U.S. for ultra-high field magnets". Superconductor Science and Technology 35, n.º 4 (23 de febrero de 2022): 043001. http://dx.doi.org/10.1088/1361-6668/ac5162.

Texto completo

Resumen

Abstract High-temperature superconductors (HTSs) make it possible to achieve magnetic fields beyond the 23.5 T limit of low-temperature superconductors. For higher energy density, high-performance HTS with J e > 1000 A mm−2 enables reduction in coil winding length and a smaller magnet size. Among HTS, REBa2Cu3O7−δ (REBCO, RE = rare earth) exhibits excellent mechanical properties and superior performance over a wide range of temperatures and magnetic fields. REBCO tapes can be converted to various formats, including round wires. The state-of-the-art REBCO superconductors for ultra-high field magnets, including cable/wire architectures, are reviewed. R&D needs to address the remaining challenges with REBCO superconductors for ultra-high magnetic field applications is discussed.

Los estilos APA, Harvard, Vancouver, ISO, etc.

37

Park, Jiwon, Chaehwa Jeong, Moony Na, Yusik Oh, Yongsoo Yang y Hye Ryung Byon. "Pulse Electrodeposition of Cu on Porous Ag Framework for Electrochemical CO₂ Conversion to Ethanol". ECS Meeting Abstracts MA2022-01, n.º 39 (7 de julio de 2022): 1776. http://dx.doi.org/10.1149/ma2022-01391776mtgabs.

Texto completo

Resumen

Electrochemical conversion of carbon dioxide (CO2) gas is a simple and cost-benefit method to produce economically valuable materials such as carbon monoxide (CO), multi-carbon (C2+) oxygenate, and hydrocarbons. In particular, ethanol (EtOH) production is attractive to be applied for conventional transport fuels. However, there has been a lack of techniques to yield predominant EtOH from CO2. Copper (Cu), as the well-known and exclusive C2+ catalyst, thermodynamically prefers the production of (C2H4) compared to EtOH. Previous studies suggested that increased concentration of carbon monoxide (CO) as the intermediate of CO2 ameliorated the EtOH selectivity.1,2 Because the solubility of CO is very little in an aqueous electrolyte solution, surface diffusion of CO has been considered to enhance the local CO concentration. It suggests that catalyst interface is crucial to increasing EtOH yield, while little knowledge was developed. We prepared porous Ag inverse opal (AgIO) frameworks with a uniform pore size of ~ 600 nm. The CO2 gas was electrochemically reduced to CO with > 90% selectivity at -1.05 V vs. RHE. In addition, the CO settled in the pore, providing an opportunity for sequential electrochemical/chemical reactions. We deposited the ultra-thin Cu layer (2~10 nm) upon the Ag surface through the pulse electrodeposition technique (PED). This catalyst, indicated as PEDCu/AgIOs, performed ~33 % Faradaic efficiency (FE) of EtOH at -1.05 V vs. RHE. Moreover, PEDCu/AgIOs showed a high oxygenates ratio relative to hydrocarbons (FEoxygenate/FEC2H4) of 2.28, while H2 evolution was significantly suppressed. These results suggested that as-prepared thin Cu film was partially segregated, and the Ag surface was exposed, forming the mixed Ag and Cu interfaces in the given electrochemical condition. This hypothesis was confirmed by negligible EtOH from the Ag-free CuIOs structure. More importantly, the resulting EtOH selectivity outperformed Cu nanoparticles (~7 nm diameter) dispersed on AgIOs (7.45 % FE) and aggregated Cu nanostructures on AgIOs (17.65 % FE) prepared by the constant current mode of electrodeposition. We, therefore, anticipated that CO spillover was promoted by the remaining and ultra-thin Cu layer. Further experiments were conducted by controlling of the thickness, pore size, and interpore size of AgIO frameworks to understand their roles. PEDCu/AgIOs with larger AgIOs thickness and smaller pore size showed higher EtOH selectivity, while the interpore size did not significantly affect the product selectivity. In the presentation, I will discuss key parameters to determine EtOH selectivity and the presumable pathway of EtOH production in details. References Ting, L. R. L.; Piqué, O.; Lim, S. Y.; Tanhaei, M.; Calle-Vallejo, F.; Yeo, B. S., Enhancing CO2 Electroreduction to Ethanol on Copper–Silver Composites by Opening an Alternative Catalytic Pathway. ACS Catal. 2020, 10 (7), 4059-4069. Gurudayal; Perone, D.; Malani, S.; Lum, Y.; Haussener, S.; Ager, J. W., Sequential Cascade Electrocatalytic Conversion of Carbon Dioxide to C-C Coupled Products. ACS Appl. Energy Mater. 2019, 2 (6), 4551-4559.

Los estilos APA, Harvard, Vancouver, ISO, etc.

38

Pashazadeh, Sara, Biuck Habibi, Ali Pashazadeh, Ali Fatemi y Milad Rasouli. "(Digital Presentation) Facile Fabrication of Graphene Quantum Dot- Doped Polyaniline Embedded Cu Metal-Organic Frameworks Composite Electrode As Improved Anode Electrocatalyst for Methanol Oxidation". ECS Meeting Abstracts MA2022-01, n.º 41 (7 de julio de 2022): 2491. http://dx.doi.org/10.1149/ma2022-01412491mtgabs.

Texto completo

Resumen

Nonrenewable energy sources accounted for roughly 80% of total energy consumption [1]. Solar energy, wind energy, geothermal energy, hydropower, and fuel cells (FCs) have all recently been described as renewable energy sources. In commercial uses, renewable energy has experienced meteorological and logistical obstacles. Because of advantages such as simple fabrication/operation conditions, eco-friendly, high energy conversion efficiency, and long-term durability, FCs technologies are considered one of the most important renewable energy sources for many applications such as portable devices, cars, and electricity plants [2–5]. Methanol can be utilized in direct methanol fuel cells (DMFC) to produce clean energy that can be used in smart electronic gadgets or small automobiles in this regard [6]. However, before DMFC can be used commercially, the slow oxidation kinetics and catalyst toxicity [7] must be resolved. Therefore, the development of direct methanol fuel cells (DMFCs) is one of the most promising technologies for the applications of these devices in stationary power supplies and electric vehicles [8]. Apart from the future of mobile devices such as mobile chargers, phones, computers, and many other applications, this energy is environmentally benign because no gases are emitted and the waste is simply clean water. The biggest issue that this technique may encounter is its high cost due to the usage of noble metal catalysts (platinum (Pt) and ruthenium (Ru)) [9]. Methanol is oxidized via a multi-electron process and several products and/or intermediates can be formed, depending on the electrolyte and the nature of the electrode. Electrode materials are important parameters in the electrochemical oxidation of methanol, where high efficient electrocatalysts are needed. Several metal oxides such as Fe2O3, CeO2, MoOx, Co3O4, NiO, and CuO has been used in various applications, such as catalysis, water splitting photocatalysis, solar cells and gas sensing, besides their uses to enhance the electrocatalytic activity for methanol oxidation [10-11]. This paper describes the preparation of graphene quantum dot-doped polyaniline embedded copper metal-organic frameworks composite catalysts for investigating methanol oxidation in alkaline solutions. The electrode surface was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and electrochemical impedance spectroscopy (EIS). After physicochemical characterizations of graphene quantum dot-doped polyaniline embedded copper metal-organic frameworks composite modified carbon ceramic electrode (Cu- MOF/GQDs-PAN/CCE), its electrocatalytic and stability characterizations toward methanol oxidation in alkaline media were investigated in detail by cyclic voltammetry and chronoamperometry. Results showed that, the electrocatalytic activity of the Cu- MOF/GQDs-PAN/CCE electrode is much higher than those of unmodified electrode under similar experimental conditions, showing the possibility of attaining good electrocatalytic anodes for fuel cells. Kinetic parameters such as the electron transfer coefficient (α) and the number of electrons involved in the rate determining step (nα) for the oxidation of methanol were determined utilizing cyclic voltammetry (CV). Keywords: Graphene quantum dot, Polyaniline, Metal-organic frameworks, electrocatalyst, Methanol References [1] S.K. Kamarudin, F. Ahmad, W.R.W. Daud, Overview on application of direct methanol fuel cell (DMFC) for portable electronic devices, Int. J. Hydrog. Energy 34 (2009) 6902–6916. [2] L. Carrette, K.A. Friedrich, U. Stimming, Fuel cells: principles, types, fuels and applications, ChemPhysChem 1 (2000) 162–193. [3] A.B. Stambouli, Fuel cells: The expectations for an environmental-friendly and sustainable source of energy, Renew. Sustain. Energy Rev. 15 (9) (2011) 4507– 4520. [4] P. Joghee, J.N. Malik, S. Pylypenko, R. O’Hayre, A review on direct methanol fuel cells – In the perspective of energy and sustainability, MRS Energy Sustain. 2 (2015), https://doi.org/10.1557/mre.2015.4. [5] D. Hassen, M.A. Shenashen, S.A. El-Safty, M.M. Selim, H. Isago, A. Elmarakbi, H. Yamaguchi, Nitrogen-doped carbon-embedded TiO2 nanofibers as promising oxygen reduction reaction electrocatalysts, J. Power Sources 330 (2016) 292– 303. [6] M. Mansor, S.N. Timmiati, K.L. Lim, W.Y. Wong, S.K. Kamarudin, N.H. Nazirah Kamarudin, Recent progress of anode catalysts and their support materials for methanol electrooxidation reaction, Int. J. Hydrogen Energy 44 (29) (2019) 14744–14769, https://doi.org/10.1016/j.ijhydene.2019.04.100. [7] Z. Mousavi, A. Benvidi, S. Jahanbani, M. Mazloum-Ardakani, R. Vafazadeh, H. R. Zare, Investigation of electrochemical oxidation of methanol at a carbon paste electrode modified with Ni(II)-BS complex and reduced graphene oxide nano sheets, Electroanalysis 28 (12) (2016) 2985–2992, https://doi.org/10.1002/ elan.201501183. [8] S. Wasmus, A. Küver, Methanol oxidation and direct methanol fuel cells: a selective review, J. Electroanal. Chem. 461 (1-2) (1999) 14–31. [9] M. Liu, R. Zhang, W. Chen, Graphene-Supported Nanoelectrocatalysts for Fuel Cells: Synthesis, Properties, and Applications, Chem. Rev. 114 (2014) 5117– 5160. [10] N. Spinner, W.E. Mustain, Electrochim. Acta 56 (2011) 5656. [11] M.S. Risbud, S. Baxter, M. Skyllas-Kazacos, Open Fuels Energy Sci. J. 5 (2012) 9.

Los estilos APA, Harvard, Vancouver, ISO, etc.

39

Stando, Grzegorz Jan, Haitao Liu, Lei Li y Dawid Janas. "(Digital Presentation) Wettability of Carbon Nanostructures – Hydrophobic or Hydrophilic?" ECS Meeting Abstracts MA2023-01, n.º 10 (28 de agosto de 2023): 1233. http://dx.doi.org/10.1149/ma2023-01101233mtgabs.

Texto completo

Resumen

Nanocarbon nanostructures have significant potential to be applied in: filtration[1], energy storying[2], thermogenerators[3], electronics[4], and part of composite materials due to their enormous properties[2]. They characterized magnificent electrical, thermal, and mechanical properties. Many people think their surface nature is hydrophobic. However, more and more scientific publications present the opposite statement about carbon nanotubes and graphene[5-7]. The reason for hydrophobicity is undefined hydrocarbons, which are adsorbed on the nanocarbon surface. The surface character is a crucial parameter for such applications as: electrode materials for storage energy and integration degree between a part of composites. The surface of fullerene C60, high quality (ID/IG = 0.01) single-walled carbon nanotubes (SWCNTs), single-layer graphene (SLG) deposed on copper foil have been investigated to understand the phenomenon of hydrophobic surface and prove that there are intrinsic hydrophilic. A coating from C60 was deposed on glass by spin coating and free-standing film from SWCNTs by method described in previous work. SLG on Cu was synthesized by CVD method. The water contact angle (WCA) was used to define character of surface. The sample was annealed in atmosphere H2/Ar (C60 and SLG) and air (SWCNTs) to remove surface impurities. WCA was measured after/before annealing. Initial C60 and SWCNTs have hydrophobic (WCA >90), SLG has slightly hydrophilic (about 80 ºC). After annealing the surface, all of them have a strongly hydrophilic character, which was even superhydrophilic for C60 and SWCNTs. The nanomaterials were characterized after/before annealing by many techniques such as: Raman spectroscopy, X-ray photoelectron spectroscopy, Scanning electron microscopy, Atomic force microscopy, and Attenuated total reflectance-Fourier transform infrared spectroscopy. All of them showed that the nanostructures had not been damaged during the surface purification process. Moreover, after a month of exposure to air, the WCA has increased. The samples were again analyzed by the techniques mentioned before and the reason for changing the surface characters was hydrocarbons. To indeficate the them selected groups of organic compound was deposed onto nanocarbon surface and the experimental results manifested that aromatic hydrocarbons are the main reason of hydrophobicity of the surface. References: [1] J. H. Ding, H. R. Zhao and H. Bin Yu, Sci. Rep., , DOI:10.1038/s41598-018-23859-5. [2] F. Liu, S. Luo, D. Liu, W. Chen, Y. Huang, L. Dong and L. Wang, ACS Appl. Mater. Interfaces, 2017, 9, 33791–33801. [3] R. Wu, H. Yuan, C. Liu, J. Le Lan, X. Yang and Y. H. Lin, RSC Adv., 2018, 8, 26011–26019. [4] P. G. Collins, M. S. Arnold and P. Avouris, Science (80-. )., 2001, 292, 706–709. [5] D. Janas and G. Stando, Sci. Rep., , DOI:10.1038/s41598-017-12443-y. [6] F. Yang, G. Stando, A. Thompson, D. Gundurao, L. Li and H. Liu, Accounts Mater. Res., 2022, 3, 1022–1032. [7] H. Liu, J. Zhai and L. Jiang, Soft Matter, 2006, 2, 811–821. Acknowledgment: G.S. would like to thank the Ministry of Science and Higher Education of Poland for financial support of scientific work from budget funds for science in the years 2019–2023 as a research project under the “Diamond Grant” program (grant agreement 0036/DIA/201948) and National Agency for Academic Exchange of Poland (under the Iwanowska program, grant agreement PPN/IWA/2019/1/00017/UO/00001) for financial support during the stay at the University of Pittsburgh in the USA. Part of the work was finial support by NSF (CBET-2028826).

Los estilos APA, Harvard, Vancouver, ISO, etc.

40

Yamamoto, Kentaro, Yanchang Wang, Hisao Kiuchi, Toshiyuki Matsunaga, Toshiki Watanabe, Hidenori Miki, Hideki Iba et al. "Intercalation Reaction Mechanism of Fluoride-Ions in (Ca, Sr)FeO₂ Cathodes with Infinite Layer Structure for All-Solid-State Fluoride-Ion Batteries". ECS Meeting Abstracts MA2023-02, n.º 4 (22 de diciembre de 2023): 668. http://dx.doi.org/10.1149/ma2023-024668mtgabs.

Texto completo

Resumen

Fluoride ion batteries, which use fluoride ions as carriers, are attracting attention as the next generation of storage batteries because of their theoretical high energy density. Conventional research has focused on metal/metal fluorides such as Cu/CuF2 as cathode materials.[1] However, these cathodes have disadvantages of the power density and cyclability due to the rapid decrease in electronic conductivity and large volume change during fluorination and defluorination. To solve these problems, cathode materials that utilize topotactic fluoride ion intercalation reactions, similar to electrode materials applied in lithium-ion secondary batteries, are being developed[2]. However, these materials have the disadvantage of relatively small capacity, compared to metal/metal fluorides.In this study, we focused on SrFeO2and Ca-doped SrFeO2 cathodes with infinite layer structure as new high-capacity intercalation cathodes, and evaluated its electrochemical properties and clarified the charge compensation mechanism. Ca1-xSrxFeO2 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) was synthesized by a low-temperature reduction method using CaH2. Ca1-xSrxFeO2/La0.9Ba0.1F2.9/vapor grown carbon fiber (VGCF) was used as the composite cathode, La0.9Ba0.1F2.9 as the electrolyte and Pb/PbF2/ La0.9Ba0.1F2.9/VGCF as the composite anode to construct the electrochemical cell of the piezoelectric material. Charge-discharge measurements were carried out in the cut-off voltage range of -1.5 to 3.0 V at 140°C. X-ray absorption spectroscopy (XAS) measurements of Fe K-edge, O K-edge, and F K-edge and resonant inelastic X-ray scattering (RIXS) measurements of O K-edge were performed on the samples after charging and discharging. All the Ca1-xSrxFeO2 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) cathode showed voltage plateaus around -0.5 V and 1.5 V during charging, and the maximum discharge capacity (580 mAh g-1) was obtained when x = 0.8, and the cathodes could be repeatedly charged and discharged. XAS of the Fe K-edge revealed that Fe compensated for the charge in the flat potential region around -0.5 V. XAS and RIXS measurements of the O K-edge revealed that the charge compensation was carried out by the formation of O2 molecules (oxidation of oxide ions), as which is observed in lithium-excess metal oxide on charge process[4], in the voltage plateau around 1.5 V. Using inexpensive Ca and Fe, we succeeded in developing an intercalation cathode material that significantly exceeds the capacity of conventional lithium-ion battery cathodes. References: [1] D. Zhang, K. Yamamoto, Y. Uchimoto et al., J. Mater. Chem. A, 2021, 9, 406–412. [2] Y. Wang, K. Yamamoto, Y. Uchimoto, et al., Chem. Mater., 2022, 34, 609–616. [3] C. Tassel, T. H. Kageyama, et al., J. Am. Chem. Soc., 2008, 130, 3764–3765. [4] R. A. House, P. G. Bruce, et al., Nat. Energy 2020, 5, 777–785. Acknowledgement: This research was financially supported by Grant-in-Aid for Scientific Research (B) (JSPS KAKENHI Grant Number JP21H02048).

Los estilos APA, Harvard, Vancouver, ISO, etc.

41

Putra, Ridwan Pratama, Kyosuke Matsushita, Tsuyoshi Ohnishi y Takuya Masuda. "Operando Nanomechanical Mapping of Silicon Thin Film Electrode during the First Lithiation and Delithiation Investigated By Bimodal Atomic Force Microscopy". ECS Meeting Abstracts MA2023-01, n.º 4 (28 de agosto de 2023): 814. http://dx.doi.org/10.1149/ma2023-014814mtgabs.

Texto completo

Resumen

Si is emerging as one of the most prospective anode materials for all-solid-state Li-ion batteries due to its extremely high theoretical capacity density of 4200 mAh g-1 and relatively negative potential for lithiation/delithiation. Towards its widespread use, controlling severe volume expansion/contraction during lithiation/delithiation is a challenge because it may cause cracking, fracture, and pulverization that negatively influence the cycle performance and rate capability of the cells [1]. Such mechanical event is induced by the change in the lattice structure due to the formation of LixSi and successive increasing/decreasing of Li content x in LixSi [2]. Bimodal atomic force microscopy (AFM) offers quantitative mapping of nanoscale mechanical property, simultaneously with surface topography imaging [3]. Our group previously applied this technique to the cross-section of a composite electrode consist of active materials, binders, conductive additives, and deposited electrolyte solution and successfully demonstrated nanomechanical mapping [4]. Here, we develop an operando bimodal AFM system to track Young’s modulus changes of electrode materials in an all-solid-state battery configuration during the lithiation and delithiation reactions in real-time. A cell in a Cu/Si/LLZT/In/Li configuration was fabricated as follows; a 3 µm-thick Si thin-film and a 100 nm-thick Cu layer were sputter-deposited on one side of Li6.6La3Zr1.6Ta0.4O12 (LLZT) solid electrolyte, an In layer was sputter-deposited on the other side of LLZT, the Cu/Si/LLZT/In sample was milled with an Ar-ion beam to yield a flat and smooth cross-section suitable for AFM analysis, and then a 50 µm-thick Li metal foil was combined with the pre-coated In thin layer. Operando nanomechanical mapping was performed by mounting the cross-section-exposed cell in the custom-made sample holder coupled with a potentiostat for bias applications, in an Ar-filled glove box to prevent any atmospheric influences. Electrochemical lithiation and delithiation were carried out within a potential window of 0.01-1.20 V vs. Li/Li+. Electrochemical characterization indicated that the capacities of the Si electrode for the first lithiation and delithiation are 3300 and 1833 mAh g-1, respectively. These capacities are equal to the formation of Li3.46Si after the first lithiation of the pristine Si and Li1.54Si after the successive delithiation from Li3.46Si. Throughout the lithiation, the averaged Young’s modulus of Si electrode decreased due to the formation of LixSi and increase in the Li content x in LixSi. In the initial stage of lithiation, it drastically decreased because LixSi was formed by the lithiation of pristine Si. Then, it moderately decreased with increasing Li content x in LixSi. Unfortunately, the Young’s modulus maps were only recorded until the formation of Li1.54Si because the successive delithiation was not completed possibly due to the phase transformation of crystalline LixSi to amorphous LixSi [5], which may cause a significant mechanical strain inside the thin film. The measured Young’s modulus values were consistent with those obtained by first principle calculation [6]. Further details are given at the presentation. References: J. Zhong, T. Wang, L. Wang, L. Peng, S. Fu, M. Zhang, J. Cao, X. Xu, J. Liang, H. Fei, X. Duan, B. Lu, Y. Wang, J. Zhu and X. Duan, Nano-Micro Letters, 14, 50 (2022). M. T. McDowell, S. W. Lee, W. D. Nix and Y. Cui, Advanced Materials, 25, 4966 (2013). M. Kocun, A. Labuda, W. Meinhold, I. Revenko and R. Proksch, ACS Nano, 11, 10097 (2017). H. Sakai, Y. Taniguchi, K. Uosaki and T. Masuda, Journal of Power Sources, 413, 29 (2019). R. Endo, T. Ohnishi, K. Takada and T. Masuda, The Journal of Physical Chemistry Letters, 13, 7363 (2022). H. Kim, C.-Y. Chou, J. G. Ekerdt and G. S. Hwang, The Journal of Physical Chemistry C, 115, 2514 (2011).

Los estilos APA, Harvard, Vancouver, ISO, etc.

42

El-Zoka, Ayman A. "(Invited) Making Nanostructured Composites Via Inner-Pore Electrodeposition into Nanoporous Metals". ECS Meeting Abstracts MA2023-02, n.º 21 (22 de diciembre de 2023): 1281. http://dx.doi.org/10.1149/ma2023-02211281mtgabs.

Texto completo

Resumen

The selective removal of Ag from a solid solution of Ag-Au or Ag-Au-Pt yields a 3D bicontinuous, open-pore, nanoporous gold substrate (NPG), that is rich in the more noble metal(s)1 (Au and/or Pt). NPG has been successfully developed by the intelligent use of the conventionally-undesired dealloying corrosion. The excellent properties of NPG are attributed to the surface area-to-volume ratio, and high curvature of nanoligament surfaces2,3 . While a lot of recent research has been focusing on the structure/property relationships of NPG as a functional material in its own right4,5, the further use of NPG as a sophisticated template for fabricating complex nanostructured materials is worthy of attention. Previous work on atom probe tomography characterization of NPG6,7 showed the successful inner-pore electrodeposition of a fully compact Cu support, thus, opening the door to implementing that newly developed method to the creation of finely tuned nanostructures, using NPG as a template. Fabrication of functional nanostructures pertaining to the interests of the catalysis and mechanics communities will be demonstrated through the electrodeposition of Cu and Co on NPG. Key aspects that enable this unexpected complete infiltration of NPG layer will be highlighted including, a characteristic "subpotential" curvature-driven electrodeposition regime8. Insights on the associated electrodeposition mechanisms are gained through the pairing of electrochemical methods and high-resolution characterization techniques. Furthermore, recent advances in structural and chemical modifications that increase the complexity and tunability of NPG-based nanocomposites will be discussed for the first time. References Newman, R. C. 2.05 - Dealloying. in Shreir’s Corrosion (eds. Cottis, B. et al.) 801–809 (Elsevier, 2010). Zielasek, V. et al. Gold Catalysts: Nanoporous Gold Foams. Angewandte Chemie International Edition 45, 8241–8244 (2006). Xue, Y., Markmann, J., Duan, H., Weissmüller, J. & Huber, P. Switchable imbibition in nanoporous gold. Nature Communications 5, (2014). Wittstock, A., Wichmann, A., Biener, J. & Bäumer, M. Nanoporous gold: A new gold catalyst with tunable properties. Faraday Discuss (2011) doi:10.1039/c1fd00022e. Li, X. et al. Nanoporous-Gold-Based Hybrid Cantilevered Actuator Dealloyed and Driven by A Modified Rotary Triboelectric Nanogenerator. Sci Rep (2016) doi:10.1038/srep24092. El-Zoka, A. A., Langelier, B., Botton, G. A. & Newman, R. C. Enhanced analysis of nanoporous gold by atom probe tomography. Mater Charact 128, (2017). El-Zoka, A. A., Langelier, B., Korinek, A., Botton, G. A. & Newman, R. C. Nanoscale mechanism of the stabilization of nanoporous gold by alloyed platinum. Nanoscale 10, (2018). Lee, L., He, D., Carcea, A. G. & Newman, R. C. Exploring the reactivity and nanoscale morphology of de-alloyed layers. Corros Sci 49, 72–80 (2007).

Los estilos APA, Harvard, Vancouver, ISO, etc.

43

Zhang, Yingying, Dandan Hu, Huajun Yang, Jian Lin y Tao Wu. "Synthesis, crystal structure, near-IR photoelectric response of two 1-D selenides: [Cu 2 MSe 5 ]·[Mn(H + -en) 2 (en)] (M=Ge, Sn)". Journal of Solid State Chemistry 251 (julio de 2017): 61–64. http://dx.doi.org/10.1016/j.jssc.2017.04.006.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

44

Wang, Duo-Zhi, Xin-Fang Wang, Jia-Qiang Du, Jun-Liang Dong y Fei Xie. "2-(hydroxymethyl)-1H-benzo[d]imidazole-5-carboxylic acid as linker for Co(II)/Ni(II)/Cu(II) coordination polymers: Synthesis, structures and properties". Journal of Solid State Chemistry 258 (febrero de 2018): 728–36. http://dx.doi.org/10.1016/j.jssc.2017.12.007.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

45

Sah, Ajay K., Merii Kato y Tomoaki Tanase. "Trinuclear coordinatively labile Cu(ii) complex of 4,6-O-ethylidene-β-d-glucopyranosylamine derived Schiff base ligand and its reactivity towards primary alcohols and amines". Chem. Commun., n.º 5 (2005): 675–77. http://dx.doi.org/10.1039/b413923b.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

46

Castello, Carolina, Maria Vincenza Pagliaro, Francesco Bartoli, Marco Bellini, Tailor Peruzzolo, Enrico Berretti, Hamish Andrew Miller y Francesco Vizza. "Silver-M-Phathalocyanine (M= Co,Fe,Cu) Electrocatalysts for Oxygen Reduction Reaction in H₂/O₂ Anion Exchange Membrane Fuel Cells". ECS Meeting Abstracts MA2023-02, n.º 41 (22 de diciembre de 2023): 2023. http://dx.doi.org/10.1149/ma2023-02412023mtgabs.

Texto completo

Resumen

In the transition from fossil fuels to clean energy sources, H2 plays a key role due to its high energy density, and direct conversion to electricity in fuel cells (FCs). FCs are devices that allow the clean conversion of chemical energy into electrical energy. In H2/O2 fuel cell the hydrogen oxidation reaction (HOR) occurs at the anodic electrode, while at the cathodic side oxygen is reduced into water (ORR). The electrodes are separated by a conductive membrane, that could exchange protons (Proton Exchange Membrane, PEM) or anions (Anion Exchange Membrane, AEM) to maintain the electro-neutrality of the system. AEMFCs are an attractive alternative to PEMFCs, thanks to the alkaline noncorrosive enviroment that allows the use of cheaper structural materials such as non-noble metal electrocatalysts. This work is centred on the study of silver (Ag) nanostructured electrocatalysts in ORR for the realization of a platinum-free AEMFCs. Ag nanoparticles promote, in alkaline media, a 4e- pathway of the ORR, optimizing the conversion of oxygen into water at the expense of hydrogen peroxide.1 However, the activity of Ag is limited by the strong hydroxide anion (OH-) binding energy, which reduces the free active sites destined to oxygen adsorption.1 To overcome this, Ag electrocatalysts were modified with metal-phthalocyanines (M-Pc M=Co, Fe, Cu) and supported on Ketjen-black carbon and on Ceria/Ketjen black (CeO2/C) supports. The synergistic effect between M-Pc and Ag NPs optimizes the OH- binding energy enhancing the ORR performances.2,3 The employment of ceria, thanks to its high oxophylicity, improves the transfer of OH- to the metal surface.4,5 The dispersion and size of nanoparticles (5-15 nm) was controlled through the Turkevich synthesis method, in order to maximize the interaction between Ag and Me-Pc. Physical characterization has been realized by High Resolution Trasmission Electron Microscopy (HR-TEM), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) while electrochemical behaviour has been explored in half cells and in complete AEMFCs. References Erikson, H., Sarapuu, A., & Tammeveski, K. (2019). Oxygen reduction reaction on silver catalysts in alkaline media: a minireview. ChemElectroChem, 6(1), 73-86.. Miller, H. A., Bevilacqua, M., Filippi, J., Lavacchi, A., Marchionni, A., Marelli, M., ... & Vizza, F. (2013). Nanostructured Fe–Ag electrocatalysts for the oxygen reduction reaction in alkaline media. Journal of Materials Chemistry A, 1(42), 13337-13347. Miller, H. A., Bellini, M., Oberhauser, W., Deng, X., Chen, H., He, Q., ... & Vizza, F. (2016). Heat treated carbon supported iron (ii) phthalocyanine oxygen reduction catalysts: elucidation of the structure–activity relationship using X-ray absorption spectroscopy. Physical Chemistry Chemical Physics, 18(48), 33142-33151. Miller, H. A., Bellini, M., Dekel, D. R., & Vizza, F. (2022). Recent developments in Pd-CeO2 nano-composite electrocatalysts for anodic reactions in anion exchange membrane fuel cells. Electrochemistry Communications, 135, 107219. Bellini, M., Pagliaro, M. V., Marchionni, A., Filippi, J., Miller, H. A., Bevilacqua, M., ... & Vizza, F. (2021). Hydrogen and chemicals from alcohols through electrochemical reforming by Pd-CeO2/C electrocatalyst. Inorganica Chimica Acta, 518, 120245. Figure 1

Los estilos APA, Harvard, Vancouver, ISO, etc.

47

Fang, Yuxin y John Flake. "Functionalized Silica Facilitated Proton Coupled Electron Transfer in Electrochemical CO₂ Reduction on Pd". ECS Meeting Abstracts MA2018-01, n.º 31 (13 de abril de 2018): 1824. http://dx.doi.org/10.1149/ma2018-01/31/1824.

Texto completo

Resumen

Electrochemical reduction of CO2 holds promise for renewable energy storage and electrolytic fuel generation. Previous studies have surveyed multiple aspects for engineering selective and efficient catalysts (such as size scale1, composite material2 and electrolyte co-catalysis3, etc.). Along with the density functional theory based simulation, the selectivity descriptors for the most common products CO and HCOOH are *COOH and *HCOO, respectively.4 The fact that CO reduction yields similar hydrocarbon products distribution suggests that CO is the ideal intermediate for further hydrogenated products.5 So far, only Cu-based catalysts yield energy-dense liquid hydrocarbon products6 (ie. CH3OH and C2H5OH, etc.), this can be attributed to the unique binding energies of CO* and COH*.7 Inspired by enzyme chemistry that leverage metal nanoclusters with ligands in photosynthesis8, we explored the possibility using engineered metal-ligand electrocatalyst to yield the hydrocarbon liquid products. Our previous study on thiolate-Au system has proved ligands facilitate the proton coupled electron transfer (PCET) with mild acidic pKa.9 In the present work, we considered functional ligands supported by silica facilitates the PCET in CO2 reduction on Pd nanoparticle tripled that yield of the CH3OH production. Ligand facilitated PCET with metal center that favor CO production and adsorption may be a promising strategy for selective electrochemical CO2 reduction. REFERENCE W. Zhu, R. Michalsky, Ö. Metin, H. Lv, S. Guo, C. J. Wright, X. Sun, A. A. Peterson and S. Sun, J. Am. Chem. Soc., 135, 16833 (2013). M. Watanabe, M. Shibata, A. Kato, M. Azuma and T. Sakata, J. Electrochem. Soc., 138, 3382 (1991). M. R. Thorson, K. I. Siil and P. J. A. Kenis, J. Electrochem. Soc., 160, F69 (2013). J. T. Feaster, C. Shi, E. R. Cave, T. Hatsukade, D. N. Abram, K. P. Kuhl, C. Hahn, J. K. Nørskov and T. F. Jaramillo, ACS Catalysis, 7, 4822 (2017). Y. Hori, A. Murata, R. Takahashi and S. Suzuki, J. Am. Chem. Soc., 109, 5022 (1987). Y. Hori, A. Murata and R. Takahashi, J. Chem. Soc., Faraday Trans. 1, 85, 2309 (1989). C. Shi, H. A. Hansen, A. C. Lausche and J. K. Norskov, Phys. Chem. Chem. Phys., 16, 4720 (2014). B. El-Zahab, D. Donnelly and P. Wang, Biotechnol. Bioeng., 99, 508 (2008). Y. Fang and J. C. Flake, J. Am. Chem. Soc., 139, 3399 (2017).

Los estilos APA, Harvard, Vancouver, ISO, etc.

48

Sistaninia, M., S. Terzi, A. B. Phillion, J. M. Drezet y M. Rappaz. "3-D granular modeling and in situ X-ray tomographic imaging: A comparative study of hot tearing formation and semi-solid deformation in Al–Cu alloys". Acta Materialia 61, n.º 10 (junio de 2013): 3831–41. http://dx.doi.org/10.1016/j.actamat.2013.03.021.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

49

Manzoor, K., V. Aditya, S. R. Vadera, N. Kumar y T. R. N. Kutty. "A Single-Source Solid-Precursor Method for Making Eco-Friendly Doped Semiconductor Nanoparticles Emitting Multi-Color Luminescence". Journal of Nanoscience and Nanotechnology 7, n.º 2 (1 de febrero de 2007): 463–73. http://dx.doi.org/10.1166/jnn.2007.149.

Texto completo

Resumen

A novel synthesis method is presented for the preparation of eco-friendly, doped semiconductor nanocrystals encapsulated within oxide-shells, both formed sequentially from a single-source solid-precursor. Highly luminescent ZnS nanoparticles, in situ doped with Cu+–Al3+ pairs and encapsulated with ZnO shells are prepared by the thermal decomposition of a solid-precursor compound, zinc sulfato-thiourea-oxyhydroxide, showing layered crystal structure. The precursor compound is prepared by an aqueous wet-chemical reaction involving necessary chemical reagents required for the precipitation, doping and inorganic surface capping of the nanoparticles. The elemental analysis (C, H, N, S, O, Zn), quantitative estimation of different chemical groups (SO2−4 and NH−4) and infrared studies suggested that the precursor compound is formed by the intercalation of thiourea, and/or its derivatives thiocarbamate (CSNH−2), dithiocarbamate (CS2NH−2), etc., and ammonia into the gallery space of zinc-sulfato-oxyhydroxide corbel where the ZnII ions are both in the octahedral as well as tetrahedral coordination in the ratio 3 : 2 and the dopant ions are incorporated within octahedral voids. The powder X-ray diffraction of precursor compound shows high intensity basal reflection corresponding to the large lattice-plane spacing of d = 11.23 Å and the Rietveld analysis suggested orthorhombic structure with a = 9.71 Å, b = 12.48 Å, c = 26.43 Å, and β = 90°. Transmission electron microscopy studies show the presence of micrometer sized acicular monocrystallites with prismatic platy morphology. Controlled thermolysis of the solid-precursor at 70–110 °C leads to the collapse of layered structure due to the hydrolysis of interlayer thiourea molecules or its derivatives and the S2− ions liberated thereby reacts with the tetrahedral ZnII atoms leading to the precipitation of ZnS nanoparticles at the gallery space. During this process, the dopant ions situated at octahedral voids gets incorporated into the nano-ZnS lattice and results in bright photoluminescence. On further heat treatment above 1100 °C, the corbel zinc-oxyhydroxide sheets undergo dehydroxylation to form ZnO which eventually encapsulates the ZnS nanoparticles at the gallery leading to significant enhancement in the luminescence quantum efficiency, up to ∼22%. The emission color of thus formed nano-ZnS/micro-ZnO composites could be tuned over wide spectral ranges from 480 to 618 nm and the spectral changes are attributed to a number of factors including lattice defects, Cu+–Al3+ dopant-pairs and iso-electronic oxygen in nano-ZnS and oxygen-vacancy or -interstitial centers in non-stoichiometric ZnO.

Los estilos APA, Harvard, Vancouver, ISO, etc.

50

Schmutz, Patrik, Thomas Suter y Noemie Ott. "Light Metal Alloys Local Reactivity, from AFM Based Scanning Kelvin Probe Force Microscopy (AFM-SKPFM) to Scanning Electrochemical Nanocapillary (SEN)". ECS Meeting Abstracts MA2022-02, n.º 11 (9 de octubre de 2022): 747. http://dx.doi.org/10.1149/ma2022-0211747mtgabs.

Texto completo

Resumen

Materials surface heterogeneities obviously plays a crucial role in reactivity issues and generate various types of detrimental localized corrosion attacks. In corrosion science, a first question to be addressed is how these various materials microstructure affect oxidation / passivation and localized corrosion initiation mechanisms. A methodology for microscale characterization of initial stage of surface reactions has been developed based on the Atomic Force Microscopy (AFM) Scanning Kelvin Probe Force Microscopy (AFM-SKPFM). In very early work, potential mapping with micrometer lateral resolution (lateral detection limit of materials surface heterogeneities is better but the signal has to be deconvoluted) allowed to clearly identify "cathodic" and anodic sites on Al- alloys [1]. Careful potential calibration and surface conditioning with solution exposure generating the formation of an electrochemical double layer allow obtaining local thermodynamic information closely linked to "practical electrochemical potential series" measured in bulk solution conditions. This contribution will start by revisiting some "historical" examples of AFM-SKPFM characterization (a tribute to Jerry Frankel's activities) of aluminum and magnesium alloys [1,2]. These materials surfaces will further be used to show how reaction kinetic information on corrosion processes can be obtained with similar lateral resolution by means of the newly developed Scanning Electrochemical Nanocapillary (SEN) technique. After introducing the SEN technique and methodology, the presentation will focus on showing how the combination of these two approaches allows refining the local corrosion mechanism assessment of heterogeneous materials. The SEN technique is very versatile and allows various types of electrochemical measurements to be performed with constant tracking of the topography. The technique is based on a nanocapillary glass tip (< 100 nm) excited laterally by a piezoelectric element. A control of the capillary vibration damping when approaching the surface and a feedback loop (like the tapping mode in AFM) allows a very precise control of the approach and electrolyte contact on the surface. The glass capillary filled with the electrolyte of interest integrates a reference and Pt counter electrodes to perform electrochemical measurements exposing only the area of interest to aggressive electrolytes. Using its "hopping" mode (a scan with electrochemical characterization of successive individual nanoscale areas), corrosion initiation susceptibility can be addressed. This will be illustrated through the surface reactivity study of model Al-Cu-Mg microscale intermetallics and Mg-based alloys, using SEN OCP linescans. In addition information about extend of the attack can be subsequently retrieved from SEM observations. Using the precise positioning ability of the SEN setup with X, Y and Z direction piezos, potentiodynamic polarization measurements can furthermore be performed on selected area of interest. The example of an Mg-Fe composite material will be used to discuss its local electrochemical behavior. After the presentation of the SEN characterization results, additional aspects of the measured potential by AFM-SKPFM will also be discussed as adsorbed species, especially strong dipolar molecules, can significantly contribute to the measured signal [3]. Modification of the AFM-SKPFM setup towards atmospheric corrosion investigation will finally be presented. This environmental AFM/SKPFM bridges the gap between the full electrochemical local characterizations that can be offered by the SEN technique and an "electrochemical reaction" diagnostic obtained by SKPFM in thin water layer. The example of a very reactive WC-Co composite will be presented to demonstrate the reactivity issue, galvanic coupling controlling local dissolution processes [4]. Acknowledgements Gerald Frankel for the great time I spent at Ohio State University in the Fontana Corrosion Center developing the AFM-based SKPFM methodology. Empa for internal project financial support of the SEN instrument. References [1] P. Schmutz, G.S. Frankel, J. Electrochem. Soc., 145(7) (1998), 2285-2295 [2] P. Schmutz, V. Guillaumin, S. Lillard, J. Lillard, G.S Frankel, J. Electrochem. Soc., 150(4) (2003), B99-110 (2003) [3] A. Vetushka, L. Bernard, O. Guseva,, Z. Bastl, J. Plocek, I. Tomandl, A. Fejfar, T. Baše, P. Schmutz, Physica Status Solidi (B) Basic Research, 253(3) (2016), 591-600 [4] S. Hochstrasser(-Kurz), C. Latkoczy, D. Günther, S. Virtanen, P.J. Uggowitzer, P. Schmutz, J. Electrochem. Soc., 155(8) (2008), C415-C426

Los estilos APA, Harvard, Vancouver, ISO, etc.

Artículos de revistas sobre el tema "Composite materials Cu/D"

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros