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Sugianto, Sugianto, Ngurah Made Dharma Putra, Endah F. Rahayu, Wahyu B. Widayatno, Cherly Firdharini, Slamet Priyono e Didik Aryanto. "Synthesis, Characterization, and Electrochemical Performance of Reduced Graphene Oxide-Metal (Cu,Zn)-Oxide Materials". Indonesian Journal of Science and Technology 8, n. 2 (10 marzo 2023): 329–44. http://dx.doi.org/10.17509/ijost.v8i2.56065.
Testo completoAbstract (sommario):
The reduced graphene oxide (rGO) and metal (Cu,Zn)-oxide composites were prepared using a one-step hydrothermal technique. The role of (Cu,Zn)-oxide on the physical and electrochemical properties of the composite was investigated. The composite consists of various shapes of ZnO nanoflowers and micro-spheres, as well as Cu-oxide nanoflakes and octahedron-like shapes. The (Cu,Zn)-oxides were formed in between the rGO layers and observed in the rGO-ZnO, rGO-CuO, and rGO-CuO-ZnO composites. The presence of ZnO, CuO, and rGO within the composite structure is also confirmed by the analyses of crystal structure, microstructure, and surface functional groups. Some excess impurities remaining from the surfactant give considerable differences in the electrochemical performance of the composites. The specific capacitance values of the rGO, rGO-ZnO, rGO-CuO, rGO-(0.5CuO-0.5ZnO), and rGO-(0.25CuO-0.75ZnO) composites are 9.32, 58.53, 54.14, 25.21, and 69.27 F/g, respectively. The formation ofa double metal-oxide structure as well as their insertion into the rGO sheet can significantly improve the electrochemical properties of the supercapacitor.
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Liang, Yong-Xin, Ze-Rong Ma, Si-Ting Yu, Xin-Yue He, Xu-Yang Ke, Ri-Feng Yan, Xiao-Xian Liang et al. "Preparation and property analysis of solid carbonate-oxide composite materials for an electrolyte used in low-temperature solid oxide fuel cell". Science and Technology for Energy Transition 77 (2022): 4. http://dx.doi.org/10.2516/stet/2022003.
Testo completoAbstract (sommario):
The oxide-carbonate composite electrolyte material with high ionic conductivity at low temperature has been thought that it can be used to develop LT-SOFC. However, the carbonate composite electrolyte is not easy to make it dense, especially mixing and packing oxide and carbonate to fabricate the composite electrolyte simply. In this article, rare-earth-doped CeO2 (RDC) (R = La, Sm, Gd, and Gd + Y) series samples were prepared by wet ball-milling, then sintered into fully dense and porous oxide bulk at 1500–1600 °C and 1000 °C. Melted carbonate LNCO, composed of Li2CO3 and Na2CO3 at a molar ratio of 1:1, was combined with porous oxide bulk materials using a bath method at 500 °C for 10 h to prepare a dense carbonate-oxide composite electrolyte. The dense oxide-carbonate composite electrolyte always obtains by this fabrication process. Boiling water was used to remove carbonate from these composites. Lattice parameters were obtained through Rietveld refinement, and a calculation procedure for quantifying the composite density was proposed. The quantified composite density results were verified through scanning electron microscopy microstructure observations. The Ce valence in the RDC oxides and RDC-carbonate composite was analyzed by X-ray absorption near edge structure spectroscopy to observe the effects of heat treatment temperature and carbonate on the Ce4+/Ce3+ mixed-valence state in doped CeO2.
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Chausov, Denis N., Veronika V. Smirnova, Dmitriy E. Burmistrov, Ruslan M. Sarimov, Alexander D. Kurilov, Maxim E. Astashev, Oleg V. Uvarov et al. "Synthesis of a Novel, Biocompatible and Bacteriostatic Borosiloxane Composition with Silver Oxide Nanoparticles". Materials 15, n. 2 (11 gennaio 2022): 527. http://dx.doi.org/10.3390/ma15020527.
Testo completoAbstract (sommario):
Microbial antibiotic resistance is an important global world health problem. Recently, an interest in nanoparticles (NPs) of silver oxides as compounds with antibacterial potential has significantly increased. From a practical point of view, composites of silver oxide NPs and biocompatible material are of interest. A borosiloxane (BS) can be used as one such material. A composite material combining BS and silver oxide NPs has been synthesized. Composites containing BS have adjustable viscoelastic properties. The silver oxide NPs synthesized by laser ablation have a size of ~65 nm (half-width 60 nm) and an elemental composition of Ag2O. The synthesized material exhibits strong bacteriostatic properties against E. coli at a concentration of nanoparticles of silver oxide more than 0.01%. The bacteriostatic effect depends on the silver oxide NPs concentration in the matrix. The BS/silver oxide NPs have no cytotoxic effect on a eukaryotic cell culture when the concentration of nanoparticles of silver oxide is less than 0.1%. The use of the resulting composite based on BS and silver oxide NPs as a reusable dry disinfectant is due to its low toxicity and bacteriostatic activity and its characteristics are not inferior to the medical alloy nitinol.
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Aslam, Junaid, e Yong Wang. "Metal Oxide Wrapped by Reduced Graphene Oxide Nanocomposites as Anode Materials for Lithium-Ion Batteries". Nanomaterials 13, n. 2 (11 gennaio 2023): 296. http://dx.doi.org/10.3390/nano13020296.
Testo completoAbstract (sommario):
The reduced graphene oxide/iron oxide (rGO/Fe2O3) and reduced graphene oxide/cobalt oxide (rGO/Co3O4) composite anodes have been successfully prepared through a simple and scalable ball-milling synthesis. The substantial interaction of Fe2O3 and Co3O4 with the rGO matrix strengthens the electronic conductivity and limits the volume variation during cycling in the rGO/Fe2O3 and rGO/Co3O4 composites because reduced graphene oxide (rGO) helps the metal oxides (MOs) to attain a more efficient diffusion of Li-ions and leads to high specific capacities. As anode materials for LIBs, the rGO/Fe2O3 and rGO/Co3O4 composites demonstrate overall superb electrochemical properties, especially rGO/Fe2O3T−5 and rGO/Co3O4T−5, showcasing higher reversible capacities of 1021 and 773 mAhg−1 after 100 cycles at 100 mAg−1, accompanied by the significant rate performance. Because of their superior electrochemical efficiency, high capacity and low cost, the rGO/Fe2O3 and rGO/Co3O4 composites made by ball milling could be outstanding anode materials for LIBs. Due to the excellent electrochemical performance, the rGO/Fe2O3 and rGO/Co3O4 composites prepared via ball milling could be promising anode materials with a high capacity and low cost for LIBs. The findings may provide shed some light on how other metal oxides wrapped by rGO can be prepared for future applications.
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Ros Madi, Nur Alia Farhana, Nurfatehah Wahyuny Che Jusoh, Yuki Nagao, Lian See Tan e Mariam Firdhaus Mad Nordin. "Utilizing metal oxide/fabric composites for photocatalytic degradation of wastewater". E3S Web of Conferences 516 (2024): 03004. http://dx.doi.org/10.1051/e3sconf/202451603004.
Testo completoAbstract (sommario):
The growing concern over water pollution has increased the search for innovative and sustainable approaches to wastewater treatment. This manuscript offers a concise exploration of the utilization of composite materials comprising metal oxides and fabrics for the purpose of photocatalytic degradation. Metal oxides, including titanium dioxide (TiO2), zinc oxide (ZnO), and etc possess inherent photocatalytic properties that, when combined with fabric matrices, present a synergistic approach for pollutant removal. The incorporation of metal oxides and fabrics enhances the photocatalytic performance through the improvement of the catalyst properties. This review covers the photocatalytic mechanisms and properties of metal oxide fabric composites as well as the applications of these composites in environmental remediation and wastewater treatment. As a promising avenue for sustainable pollutant mitigation, further research in this field holds the key to unlocking the full potential of metal oxide fabric composites in diverse environmental applications.
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Guo, Leyang, e Junwu Guo. "Study on the Catalytic Activity Modification of Pr and Nd Doped Ce0.7Zr0.3O2 Catalysts for Simultaneous Removal of PM and NOX". Science of Advanced Materials 16, n. 7 (1 luglio 2024): 821–28. http://dx.doi.org/10.1166/sam.2024.4679.
Testo completoAbstract (sommario):
Cerium-zirconium composite oxides (Ce0.7Zr0.3O2) have a remarkable effect on catalytic removal of carbon particles (PM) and nitrogen oxides (NOX) emitted from diesel engine, in order to further improve the thermal stability, oxygen storage capacity and low temperature catalytic REDOX performance of cerium zirconium composite oxides (Ce0.7Zr0.3O2), a small amount of Pr and Nd rare earth elements are doped to improve the catalytic activity of cerium zirconium composite oxides. In this paper, the composite oxide of Pr6O11–Nd2O3–CeO2–ZrO2 is prepared by unsteady co-precipitation method, and the physicochemical properties of the composite oxide catalyst are analyzed by BET, SEM, XRD and ICP. The gas adsorption capacity and catalytic activity of composite oxide catalysts are measured by temperature programmed reaction technology (TPR). The results show that the composite oxide of Pr0.05Nd0.05Ce0.6Zr0.3O2 prepared by using rare earth elements Pr and Nd inhibits the growth process of grain, refining the grain, and improving the sintering phenomenon at high temperature. The addition of Pr and Nd causes lattice defects, increases the number of oxygen vacancies, and improves the mobility of lattice oxygen, namely promotes oxide oxygen storage property, gas adsorption and catalytic oxidation reduction ability. After modification, Pr0.05Nd0.05Ce0.6Zr0.3O2 has good resistance to high temperature aging performance, prolongs the service life, reduces the PM lowest ignition temperature and minimum catalytic activity temperature of nitrogen oxide, and promotes the NOX reduction rate. For Pr0.05Nd0.05Ce0.6Zr0.3O2, the lowest ignition temperature of PM is about 150 °C, and the lowest catalytic activity temperature of NO is about 130 °C. The maximum CO2 production rate is 68.3%, and the maximum NO reduction rate is 45%.
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HO, M. Y., P. S. KHIEW, D. ISA, T. K. TAN, W. S. CHIU e C. H. CHIA. "A REVIEW OF METAL OXIDE COMPOSITE ELECTRODE MATERIALS FOR ELECTROCHEMICAL CAPACITORS". Nano 09, n. 06 (agosto 2014): 1430002. http://dx.doi.org/10.1142/s1793292014300023.
Testo completoAbstract (sommario):
With the emerging technology in the 21st century, which requires higher electrochemical performances, metal oxide composite electrodes in particular offer complementary properties of individual materials via the incorporation of both physical and chemical charge storage mechanism together in a single electrode. Numerous works reviewed herein have identified a wide variety of attractive metal oxide-based composite electrode material for symmetric and asymmetric electrochemical capacitors. The focus of the review is the detailed literature data and discussion regarding the electrochemical performance of various metal oxide composite electrodes fabricated from different configurations including binary and ternary composites. Additionally, projection of future development in hybrid capacitor coupling lithium metal oxides and carbonaceous materials are found to obtain significantly higher energy storage than currently available commercial electrochemical capacitors. This review describes the novel concept of lithium metal oxide electrode materials which are of value to researchers in developing high-energy and enhanced-cyclability electrochemical capacitors comparable to Li -ion batteries. In order to fully exploit the potential of metal oxide composite electrode materials, developing low cost, environment-friendly nanocomposite electrodes is certainly a research direction that should be extensively investigated in the future.
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Romanova, Iryna, e Sviatosla Kirillov. "PHYSICO-CHEMICAL PROPERTIES OF COMPOSITES ON THE BASE OF CERIA OBTAINED BY A CITRIC ACID METHOD". Ukrainian Chemistry Journal 85, n. 4 (7 giugno 2019): 98–109. http://dx.doi.org/10.33609/0041-6045.85.4.2019.98-109.
Testo completoAbstract (sommario):
Composites with the formula nMOx–СеО2, where n is the mole part of copper or manganese oxide have been synthesized via citric acid aided route. Physico-chemical properties of materials obtained are investigated by XRD, low temperature desorption of nitrogen and by temperature-programmed reduction (TPR). It is defined that the composites with the n < 0.25 (for Cu) and < 0.75 (Mn) are the solid solutions obtained by the replacement of cerium ions in the structure of fluorite (СеО2) by copper or manganese ions. The existence of the separate phases of oxides such as CuO and Mn3O4 has been identified in the XRD patterns of composites with formula 0.25CuО–СеО2 and 0.75MnOx–СеО2. The parameters of cell and the particles size for all samples are calculated; decreasing these values occurs due to the solid solutions formation. Specific area of composites obtained is much bigger than specific area of individual oxides; the biggest values are determined for the samples containing the biggest part of copper or manganese oxide. According to TPR profiles of composites themaximal intensity of low temperature peak has the composite 0.25CuО–СеО2 that means the biggest part of the solid solution; so this material is the most active in CO and ethanol combustion. This fact can be explained by appearance of additional oxygen vacancies when ions Ce4+ are replacement by ions with the less oxidation state. The quantities of hydrogen used for reduction of samples with the copper oxide and samples with the manganese oxide with n < 0.5 are much bigger than the theoretical values; in this case the reduction of the part of ceria in the solid solution is happened. The composite 0.25MnOx–CeO2 is the most active in the ethanol combustion; full conversion to CO2 is finished at 205°С. The high activity of individual oxide MnOx and the composite 0.75MnOx–СеО2 in the reaction of toluene oxidation explains by the biggest part of Mn3+ ions in their structure among the all oxides investigated.
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Matveev, E. S. "Composite Solid Electrolytes". Membrany i membrannye tehnologii 14, n. 4 (27 novembre 2024): 263–75. http://dx.doi.org/10.31857/s2218117224040027.
Testo completoAbstract (sommario):
The review describes composite electrolytes based on classical salt matrix phases, and also shows the possibilities of creating composites using simple or complex oxide matrices, where simple substances, salts, simple and complex oxides are used as heterogeneous dopant. The magnitude of the composite effect of electrical conductivity is discussed from the point of view of various theories of its quantitative description. The reasons for the occurrence of the composite effect are summarized. The effect of increasing ionic conductivity is due to the disorder of the surface layer in the intergranular space, amorphization or spreading of the matrix phase or the phase of heterogeneous dopant over the surface of the other phase due to the difference in surface energy, as well as the possibility of joint manifestation of these effects when using complex oxide eutectic composites with treatment above the temperature of the eutectic system.
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Li, Xiu Ping, Rong Xiang Zhao e Chu Jia Li. "Preparation and Photocatalyst of Ce/Zn Composite Oxide". Advanced Materials Research 873 (dicembre 2013): 441–44. http://dx.doi.org/10.4028/www.scientific.net/amr.873.441.
Testo completoAbstract (sommario):
With abscibe acid as combustion agent, Zn (NO3)27H2O and Ce (NO3)36H2O as raw material, the CeO2-ZnO composite oxide was synthesized by an novel combustion method. The experiment investaged the effect of molar ratio of combustion agents, Zn and Ce on composite oxides. The samples were characterized by XRD, SEM, IR, UV. The molar ratio of Ce, Zn and combustion agents is different, the composite oxides possess various morphology and properities. The photocatalytic experiment of composite oxide showed that under the optimal photocatalytic condition Methylene blue solution is completely degradated to need 240 min and under the optimal decoloring condition Methylene blue solution is completely decolorized to need 180 min.
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Zhu, Chenkai, Lei Nie, Xiaofei Yan, Jiawei Li e Dongming Qi. "Ramie fiber reinforced composites with flame retardant structure design: flammability, smoke suppression, and mechanical properties". Journal of Polymer Engineering 42, n. 1 (29 novembre 2021): 9–17. http://dx.doi.org/10.1515/polyeng-2021-0221.
Testo completoAbstract (sommario):
Abstract In this work, the structure of composite was designed as Core Stack and Surface Stack, which was treated with the expandable graphite (EG) and metal oxides such as iron oxide (IO), hydroxyapatite (HA), and aluminum tri-hydroxide (ATH). The mechanical performance of composites was characterized via flexural performance and interlaminar shear strength analysis. The flame retardance and smoke suppression of composite was explored in detail by LOI, UL-94, and cone calorimeter test. The findings presented that flexural properties of composites were observed to decrease due to delamination of surface stack, whilst no significant effect on interlaminar shear strength. In comparison with control composite, the loading of metal oxide into composite Surface Stack led to the reduction of peak heat release rate, total heat release, and fire growth index effectively. Moreover, the remarkable decrease in total smoke production could be observed due to the addition of iron oxide and the flame retardant mechanism was discussed. This study was the preliminary exploration of composite with flame retardant design which could be potential solution to improve flame retardancy and smoke suppression of composite with better mechanical structure preservation.
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Joshi, P. S., e D. S. Sutrave. "Study of Ruthenium Oxide, Manganese Oxide and Composite (Ru:Mn)O2 thin film Electrodes Assembled by Layer by Layer Spin Coating Method". Material Science Research India 13, n. 1 (6 giugno 2016): 43–49. http://dx.doi.org/10.13005/msri/130107.
Testo completoAbstract (sommario):
Ruthenium oxide, Manganese oxide and (Ru:Mn)O2 composite thin films have been prepared by 0.02M Ruthenium chloride and Manganese acetate solutions respectively on stainless steel substrates by sol-gel spin coating method. Layer by layer deposition of RuO2 and MnO2 was done for composite films. RuO2: MnO2 composite thin films have been demonstrated to be an excellent material for Supercapacitor application when evaluated with RuO2 and MnO2 thin film electrodes with respect to XRD, SEM, CV, CP and EIS studies. As a result, high specific capacitance of 515 F/g at 10 mV/s with excellent stability and long cycle life was obtained, where specific power and energy were as high as 15.38 Wh/kg and 4.06 KW/kg respectively with loading weight of 0.13 mg/cm2 .Composite films showed changes in structural and morphological features which was admiring for supercapacitor applications. The electrochemical impedance measurement was carried out in 0.1M KOH in the frequency range 10 to 105 Hz. From the analysis it can be concluded that mixed oxide composites have superior capacitive performance to single transition metal oxides as electrodes.
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Egorin, Andrei, Eduard Tokar, Anna Matskevich, Nikita Ivanov, Ivan Tkachenko, Tatiana Sokolnitskaya e Larisa Zemskova. "Composite Magnetic Sorbents Based on Iron Oxides in Different Polymer Matrices: Comparison and Application for Removal of Strontium". Biomimetics 5, n. 2 (18 maggio 2020): 22. http://dx.doi.org/10.3390/biomimetics5020022.
Testo completoAbstract (sommario):
Introduction of magnetic nanoparticles into composite sorbents based on polymer matrices has received great attention due to the possibility of using cheap iron oxides and removing spent sorbents by means of magnetic separation. In the present paper, we discuss the problem of creating magnetic sorbents using two types of matrices as host materials: synthetic cation exchange resin and natural aminopolysaccharide chitosan. The possibilities of applying matrices for the in situ formation of oxide phases of a specified composition with the required content of an inorganic component in a composite material were estimated. The composition of the oxide phase formed in the composite material was studied, and particle sizes were evaluated by the method of X-ray diffraction analysis. Magnetic characteristics were investigated. Sorption characteristics with respect to strontium for the composites containing iron oxides were determined.
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Aphesteguy, Juan C., e Silvia E. Jacobo. "Preparation and Characterization of Nanocomposites for Technological Applications". Solid State Phenomena 202 (maggio 2013): 97–111. http://dx.doi.org/10.4028/www.scientific.net/ssp.202.97.
Testo completoAbstract (sommario):
Materials with both electrical and magnetic properties are required for various applications ranging from electric and magnetic shields, molecular electronics, and sensors to microwave absorbers. Conducting polymers with the addition of magnetic oxides composites are suitable for such uses. Such is the case of the polyaniline (PANI), an organic polymer, mixed with magnetite. We have prepared through a new chemical method a PANI/ Fe3O4 composite with different amount of magnetic oxide from 0.3% m/m on the composite up to 42% m/m. The final product is a powder with good solubility in some organic solvents as chloroform. Structural morphological studies, transport properties (the electrical conductivity as a function of temperature) and magnetic characterization were performed on the oxides, on PANI and on the composites. We have explored the answer of these composites as absorbers in the microwave region to determine its potential technological application. An interesting magnetoresistance (MR) behavior was observed. The results are related to the particle size and to the influence of the percentage of oxide in the composite.
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Majumdar, Dipanwita. "An Overview on Ruthenium Oxide Composites – Challenging Material for Energy Storage Applications". Material Science Research India 15, n. 1 (30 marzo 2018): 30–40. http://dx.doi.org/10.13005/msri/150104.
Testo completoAbstract (sommario):
Ruthenium oxides owing to their high specific capacitance have been widely identified as promising materials for electrochemical charge storage devices. However, high priced ruthenium precursors restrict their commercial usage. Accordingly, numerous explorations investigated the influences on capacitive behavior of ruthenium oxide on blending with varied materials like other metal oxides, activated carbons, conducting polymers, CNTs and functionalized graphene systems as composites. The aim had been to optimize the material cost without compromising with but improving the composite electrochemical performances. The scientific explorations reveal that the overall specific capacitance of composites is a strongly related to the ruthenium oxide (RuO2) present in the system since it is the main electro-active material providing the Faradaic pseudocapacitances besides the electrical double layer contributions from the base carbon component of the composite. Major progress in the theoretical and practical research and development in this particular field has enviced a large number of research articles and technical reports in the recent past. The current investigations focus on utilizing minimum amount of metal in the composite; upholding the synergistic effect from the metal oxide and the support (carbon materials generally) to obtain better electrochemical signatures. Optimization of important factors leading to reduced nanostructure agglomeration, minimum electrostatic resistance and ultrafast proton/electrons diffusion through the hollow porous structures may ultimately result to the theoretically expected specific capacitance. Nonetheless, to the best of knowledge of the author, there is no systematic review available pertaining to recent advancement of the composites of RuO2. Thus, this overview categorically narrates recent progresses on the fabrication, performances and achievements of ruthenium oxide composite as electrode material in energy storage applications which will be beneficial especially to the newcomers in this field of research.
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Marinca, Traian Florin, Bogdan Viorel Neamțu, Florin Popa, Amalia Mesaroș e Ionel Chicinaș. "Spark Plasma Sintered Soft Magnetic Composite Based on Fe-Si-Al Surface Oxidized Powders". Materials 15, n. 22 (8 novembre 2022): 7875. http://dx.doi.org/10.3390/ma15227875.
Testo completoAbstract (sommario):
Soft magnetic composites (SMCs) need a stable matrix to apply heat treatments for enhancing their magnetic characteristics. A stable matrix can be offered by alumina, but the densification of the ferromagnetic particles covered by this oxide (by sintering) can be very difficult. This paper proposes a feasible synthesis route for obtaining alumina matrix SMCs. An Fe-Si-Al alloy with nominal composition Fe85Si9Al6 was obtained by mechanical alloying of elemental Fe, Si, and Al powders, and further, the as-milled powders were superficially oxidized by immersion in HCl solution. The oxide layer was composed of iron, silicon, and aluminum oxides, as the Fourier-transform infrared spectroscopy technique revealed. The Fe-Si-Al@oxide powder was densified by the spark plasma sintering technique—SPS. Upon sintering, a continuous matrix of oxide (mainly alumina) was formed by the reaction of the Fe-Si-Al powder coreswith their oxide layer. The main part of the composite compacts after sintering consisted of an Fe3Si-ordered phase dispersed in an oxide matrix. The DC and AC tests of magnetic composite compacts showed that upon increasing the sintering temperature, the density, magnetic induction, and magnetic permeability increased. The initial magnetic permeability was constant in the entire range of testing frequencies and the magnetic losses increased linearly. The stability of the magnetic characteristics in frequency is promising for developing further such types of magnetic composite.
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Malyshev, Sergey A., Oleg A. Shlyakhtin, Alexey S. Loktev, Galina N. Mazo, Grigoriy M. Timofeev, Igor E. Mukhin, Roman D. Svetogorov, Ilya V. Roslyakov e Alexey G. Dedov. "Ni/(R2O3,CaO) Nanocomposites Produced by the Exsolution of R1.5Ca0.5NiO4 Nickelates (R = Nd, Sm, Eu): Rare Earth Effect on the Catalytic Performance in the Dry Reforming and Partial Oxidation of Methane". Materials 15, n. 20 (18 ottobre 2022): 7265. http://dx.doi.org/10.3390/ma15207265.
Testo completoAbstract (sommario):
In order to clarify the role of R2O3 in the metal-oxide catalysts derived from complex oxide precursors, a series of R1.5Ca0.5NiO4 (R = Nd, Sm, Eu) complex oxides was obtained. A significant systematic increase in the orthorhombic distortion of the R1.5Ca0.5NiO4 structure (K2NiF4 type, Cmce) from Nd to Eu correlates with a corresponding decrease in their ionic radii. A reduction of R1.5Ca0.5NiO4 in the Ar/H2 gas mixture at 800 °C causes a formation of dense agglomerates of CaO and R2O3 coated with spherical 25–30 nm particles of Ni metal. The size of metal particles and oxide agglomerates is similar in all Ni/(R2O3,CaO) composites in the study. Their morphology is rather similar to the products of redox exsolution obtained by the partial reduction of complex oxides. All obtained composites demonstrated a significant catalytic activity in the dry reforming (DRM) and partial oxidation (POM) of methane at 700–800 °C. A systematic decrease in the DRM catalytic activity of composites from Nd to Eu could be attributed to the basicity reduction of R2O3 components of the composite catalysts. The maximum CH4 conversion in POM reaction was observed for Ni/(Sm2O3,CaO), while the maximum selectivity was demonstrated by Nd2O3-based composite. The possible reasons for the observed difference are discussed.
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Corso, Marla, Ana Carolina de Dias Albuquerque, Lídia Pereira Amaro, Lilian Keylla Berto, Silvia Luciana Favaro, Hugo Eiji Imai, Adriano Pereira Cardoso, Natália Ueda Yamaguchi e Luciana Cristina Soto Herek Rezende. "Graphene oxide synthesis for composite material preparation". Revista Ibero-Americana de Ciências Ambientais 10, n. 1 (20 giugno 2019): 157–66. http://dx.doi.org/10.6008/cbpc2179-6858.2019.001.0013.
Testo completoAbstract (sommario):
Graphene, a material formed by carbon atoms with sp2 hybridization in a hexagonal arrangement, has differentiated characteristics in comparison to commercial materials such as high flexibility, high electrical and thermal conductivity, and strong resistance due to the organized structure of the material and can be applied in several branches of research. The best-known method for the production of graphene is the exfoliation of graphite using the methodology proposed by Hummers, in which the commercial graphite is oxidized obtaining as final product the graphene oxide that can be converted into graphene. In this study, the Hummers methodology was used in the oxidation of synthetic graphite and graphene nanoplates of 5 μm and 15 μm. The obtained materials were characterized by FTIR, RAMAN and XRD, allowing to observe the best synthesis to be used in the production of graphene oxide. Then, composites were prepared using the graphene oxides obtained as filler. In order to obtain them, different mass quantities of graphene oxides (1%, 3% and 5% in relation to the polypropylene polymer matrix) were used, demonstrating by the strain tensile stress tests that the composite materials have results more satisfactory than pure polypropylene.
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Schoell, Ryan, Aspen Reyes, Guddi Suman, Mila Nhu Lam, Justin Hamil, Samantha G. Rosenberg, LaRico Treadwell, Khalid Hattar e Eric Lang. "Hot Isostatic Pressing Control of Tungsten-Based Composites". Inorganics 11, n. 2 (16 febbraio 2023): 82. http://dx.doi.org/10.3390/inorganics11020082.
Testo completoAbstract (sommario):
Metal-oxide composites are commonly used in high temperature environments for their thermal stability and high melting points. Commonly employed with refractory oxides or carbides such as ZrC and HfC, these materials may be improved with the use of a low density, high melting point ceramic such as CeO2. In this work, the consolidation of W-CeO2 metal matrix composites in the high CeO2 concentration regime is explored. The CeO2 concentrations of 50, 33, and 25 wt.%, the CeO2 particle size from nanometer to micrometer, and various hot isostatic pressing temperatures are investigated. Decreasing the CeO2 concentration is observed to increase the composite density and increase the Vickers hardness. The CeO2 oxidation state is observed to be a combination of Ce3+ and Ce4+, which is hypothesized to contribute to the porosity of the composites. The hardness of the metal-oxide composite can be improved more than 2.5 times compared to pure W processed by the same route. This work offers processing guidelines for further consolation of oxide-doped W composites.
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Singh, Tej, Chandramani Goswami, Amar Patnaik e László Lendvai. "Optimal Design of Ceramic Based Hip Implant Composites Using Hybrid AHP-MOORA Approach". Materials 15, n. 11 (26 maggio 2022): 3800. http://dx.doi.org/10.3390/ma15113800.
Testo completoAbstract (sommario):
Designing excellent hip implant composite material with optimal physical, mechanical and wear properties is challenging. Improper hip implant composite design may result in a premature component and product failure. Therefore, a hybrid decision-making tool was proposed to select the optimal hip implant composite according to several criteria that are probably conflicting. In varying weight proportions, a series of hip implant composite materials containing different ceramics (magnesium oxide, zirconium oxide, chromium oxide, silicon nitride and aluminium oxide) were fabricated and evaluated for wear and physicomechanical properties. The density, void content, hardness, indentation depth, elastic modulus, compressive strength, wear, and fracture toughness values were used to rank the hip implant composites. It was found that the density and void content of the biocomposites remain in the range of 3.920–4.307 g/cm3 and 0.0021–0.0089%, respectively. The composite without zirconium oxide exhibits the lowest density (3.920 g/cm3), while the void content remains lowest for the composite having no chromium oxide content. The highest values of hardness (28.81 GPa), elastic modulus (291 GPa) and fracture toughness (11.97 MPa.m1/2) with the lowest wear (0.0071 mm3/million cycles) were exhibited by the composites having 83 wt.% of aluminium oxide and 10 wt.% of zirconium oxide. The experimental results are compositional dependent and without any visible trend. As a result, selecting the best composites among a group of composite alternatives becomes challenging. Therefore, a hybrid AHP-MOORA based multi-criteria decision-making approach was adopted to choose the best composite alternative. The AHP (analytic hierarchy process) was used to calculate the criteria weight, and MOORA (multiple objective optimisation on the basis of ratio analysis) was used to rank the composites. The outcomes revealed that the hip implant composite with 83 wt.% aluminium oxide, 10 wt.% zirconium oxide, 5 wt.% silicon nitride, 3 wt.% magnesium oxide, and 1.5 wt.% chromium oxide had the best qualities. Finally, sensitivity analysis was conducted to determine the ranking’s robustness and stability concerning the criterion weight.
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Tran, Vinh Van, Truong Thi Vu Nu, Hong-Ryun Jung e Mincheol Chang. "Advanced Photocatalysts Based on Conducting Polymer/Metal Oxide Composites for Environmental Applications". Polymers 13, n. 18 (8 settembre 2021): 3031. http://dx.doi.org/10.3390/polym13183031.
Testo completoAbstract (sommario):
Photocatalysts provide a sustainable method of treating organic pollutants in wastewater and converting greenhouse gases. Many studies have been published on this topic in recent years, which signifies the great interest and attention that this topic inspires in the community, as well as in scientists. Composite photocatalysts based on conducting polymers and metal oxides have emerged as novel and promising photoactive materials. It has been demonstrated that conducting polymers can substantially improve the photocatalytic efficiency of metal oxides owing to their superior photocatalytic activities, high conductivities, and unique electrochemical and optical properties. Consequently, conducting polymer/metal oxide composites exhibit a high photoresponse and possess a higher surface area allowing for visible light absorption, low recombination of charge carriers, and high photocatalytic performance. Herein, we provide an overview of recent advances in the development of conducting polymer/metal oxide composite photocatalysts for organic pollutant degradation and CO2 conversion through photocatalytic processes.
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Karadimas, George, e Konstantinos Salonitis. "Ceramic Matrix Composites for Aero Engine Applications—A Review". Applied Sciences 13, n. 5 (26 febbraio 2023): 3017. http://dx.doi.org/10.3390/app13053017.
Testo completoAbstract (sommario):
Ceramic matrix materials have attracted great attention from researchers and industry due to their material properties. When used in engineering systems, and especially in aero-engine applications, they can result in reduced weight, higher temperature capability, and/or reduced cooling needs, each of which increases efficiency. This is where high-temperature ceramics have made considerable progress, and ceramic matrix composites (CMCs) are in the foreground. CMCs are classified into non-oxide and oxide-based ones. Both families have material types that have a high potential for use in high-temperature propulsion applications. The oxide materials discussed will focus on alumina and aluminosilicate/mullite base material families, whereas for non-oxides, carbon, silicon carbide, titanium carbide, and tungsten carbide CMC material families will be discussed and analyzed. Typical oxide-based ones are composed of an oxide fiber and oxide matrix (Ox-Ox). Some of the most common oxide subcategories are alumina, beryllia, ceria, and zirconia ceramics. On the other hand, the largest number of non-oxides are technical ceramics that are classified as inorganic, non-metallic materials. The most well-known non-oxide subcategories are carbides, borides, nitrides, and silicides. These matrix composites are used, for example, in combustion liners of gas turbine engines and exhaust nozzles. Until now, a thorough study on the available oxide and non-oxide-based CMCs for such applications has not been presented. This paper will focus on assessing a literature survey of the available oxide and non-oxide ceramic matrix composite materials in terms of mechanical and thermal properties, as well as the classification and fabrication methods of those CMCs. The available manufacturing and fabrication processes are reviewed and compared. Finally, the paper presents a research and development roadmap for increasing the maturity of these materials allowing for the wider adoption of aero-engine applications.
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Sanyal, Tanushree Sankar, Amanda Ineza Mugisha, Andrew Sowinski e Clémence Fauteux-Lefebvre. "Enhancement of Sulfur Oxide Capture Capacity by Deposition of Iron Oxide Particles on Graphene Oxide". Catalysts 13, n. 12 (24 novembre 2023): 1469. http://dx.doi.org/10.3390/catal13121469.
Testo completoAbstract (sommario):
Sulfur dioxide (SO2) is a known pollutant that must be captured from gas streams. Dry desulfurization processes are investigated due to their lower energy requirement and potentially high capture efficiency. Carbon materials and metal oxides have been shown to have an affinity with SO2. The aim of this study was to combine iron oxide and graphene oxide (GO) as a composite material for SO2 capture for low-concentration streams. Iron oxide particles were prepared using a polyol method in which the precursor was dispersed in ethylene glycol, heated under reflux and then deposited on GO, a two-dimensional, single-layer material with a surface area of 400 m2/g. The synthesized material was tested for continuous desulfurization in a flow-through capture system with a stream of gas containing 25 ppm SO2 entering at 20 °C and 100 °C. Under all conditions tested, the breakthrough times, evaluated when the SO2 started to be detected at the outlet with a concentration of 1 ppm, as well as the capture capacities, were significantly higher for the iron oxide GO composite than for the pristine GO alone. The presence of sulfur compounds as well as the composite composition were confirmed by energy-dispersive X-ray spectroscopy (EDXS) and X-ray photoelectron spectroscopy (XPS). The breakthrough experiment results at various temperatures also suggest that the capture was not governed only by pure physical adsorption with the presence of iron oxide. Addition of iron oxide particles positively influences SO2 affinity with the synthesized material as shown by the increase in breakthrough time and capture capacity.
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Alister G., Willis, e Saharudin Haron. "Synthesis of composite thin-film polymer consisting of tungsten and zinc oxide as hydrogen gas detector". E3S Web of Conferences 90 (2019): 01008. http://dx.doi.org/10.1051/e3sconf/20199001008.
Testo completoAbstract (sommario):
A composite polymer consisting of polyaniline (PANI) was synthesised via oxidative polymerisation by varying concentrations of transitional metal oxides and the presence of a hydrogen dissociation catalyst, palladium (Pd). The metal oxides chosen for this study were tungsten oxide (WO3) and zinc oxide (ZnO). The composite polymer samples were characterised using Fourier transform infrared (FTIR) spectroscopy where ultraviolet-visible (UV-Vis) spectroscopy was used to observe the optical changes of the thin films due to exposure to hydrogen. The FTIR spectra obtained confirmed the synthesis of PANI composite. Based on the UV-VIS analysis, PANI-ZnO composite polymer showed the highest difference in peak intensity before and after exposure to hydrogen with 11.4% difference.
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Mikhaylov, Alexey A., Alexander G. Medvedev, Dmitry A. Grishanov, Timur M. Fazliev, Vasilii Chernyshev, Elena A. Mel’nik, Tatiana A. Tripol’skaya, Ovadia Lev e Petr V. Prikhodchenko. "Electrochemical Behavior of Reduced Graphene Oxide Supported Germanium Oxide, Germanium Nitride, and Germanium Phosphide as Lithium-Ion Battery Anodes Obtained from Highly Soluble Germanium Oxide". International Journal of Molecular Sciences 24, n. 7 (6 aprile 2023): 6860. http://dx.doi.org/10.3390/ijms24076860.
Testo completoAbstract (sommario):
Germanium and germanium-based compounds are widely used in microelectronics, optics, solar cells, and sensors. Recently, germanium and its oxides, nitrides, and phosphides have been studied as active electrode materials in lithium- and sodium-ion battery anodes. Herein, the newly introduced highly soluble germanium oxide (HSGO) was used as a versatile precursor for germanium-based functional materials. In the first stage, a germanium-dioxide-reduced graphene oxide (rGO) composite was obtained by complete precipitation of GeO2 nanoparticles on the GO from an aqueous solution of HSGO and subsequent thermal treatment in argon at low temperature. The composition of the composite, GeO2-rGO (20 to 80 wt.% of crystalline phase), was able to be accurately determined by the HSGO to GO ratio in the initial solution since complete deposition and precipitation were achieved. The chemical activity of germanium dioxide nanoparticles deposited on reduced graphene oxide was shown by conversion to rGO-supported germanium nitride and phosphide phases. The GeP-rGO and Ge3N4-rGO composites with different morphologies were prepared in this study for the first time. As a test case, composite materials with different loadings of GeO2, GeP, and Ge3N4 were evaluated as lithium-ion battery anodes. Reversible conversion–alloying was demonstrated in all cases, and for the low-germanium loading range (20 wt.%), almost theoretical charge capacity based on the germanium content was attained at 100 mA g−1 (i.e., 2595 vs. 2465 mAh g−1 for Ge3N4 and 1790 vs. 1850 mAh g−1 for GeP). The germanium oxide was less efficiently exploited due to its lower conversion reversibility.
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Shivakumar, S. P., A. S. Sharan e K. Sadashivappa. "Experimental Investigations on Vibration Properties of Aluminium Matrix Composites Reinforced with Iron Oxide Particles". Applied Mechanics and Materials 895 (novembre 2019): 122–26. http://dx.doi.org/10.4028/www.scientific.net/amm.895.122.
Testo completoAbstract (sommario):
Aluminium matrix composites offer improved damping properties than other metals and its alloy. Generally pure metals and its alloys may have fairly good mechanical properties but falls short in damping properties. Aluminium matrix composites are becoming important in aerospace automobile and marine applications due to its god damping properties. The present investigation is concerned with the damping capacity of iron oxide (Fe2O3) reinforced aluminium matrix composite. The composites were fabricated with 2%, 4% and 6%, by weight of iron oxide with varied particle of size 40 μm and 500 nm in equal proportions using stir casting process. From the results obtained the 500 nm size with 4 wt% of iron oxide showed improved dynamic properties. The iron oxides reinforced with aluminum matrix are found to be new substitutes for the existing materials with low damping properties.
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Zemskova, Larisa, Andrei Egorin, Eduard Tokar, Vladimir Ivanov e Svetlana Bratskaya. "New Chitosan/Iron Oxide Composites: Fabrication and Application for Removal of Sr2+ Radionuclide from Aqueous Solutions". Biomimetics 3, n. 4 (4 dicembre 2018): 39. http://dx.doi.org/10.3390/biomimetics3040039.
Testo completoAbstract (sommario):
Here, we discuss the fabrication and problems of application of chitosan-based composite materials for the removal of hazardous metal ions from tap water and wastewater. The chitosan-based composites containing iron oxides for the uptake of Sr2+ ions were fabricated via a co-precipitation method with variation of the iron/chitosan ratio and pH of the medium. The morphology and composition of the fabricated sorbents were characterized using scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM–EDX) and X-ray diffraction (XRD) analysis. We have shown that the suggested fabrication approach allows for a homogeneous distribution of the inorganic phase in the polymer matrix. Investigations of the sorption performance of the composites have shown that they are efficient sorbents for 90Sr radionuclides uptake from tap water. The composite sorbent containing amorphous iron oxide in a chitosan matrix and calcined at 105 °C showed the best sorption characteristics. We have also demonstrated that there is an optimal iron oxide content in the composite: with increasing oxide content, the efficiency of the sorbents decreases due to poor stability in solution, especially in alkaline media. The alternative approach yielding magnetic chitosan-based composites with sufficiently good sorption performance and stability in neutral and weakly alkaline media is suggested.
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Li, Shun, Zhaofeng Chen, Zhiyuan Rao, Fei Wang, Cao Wu e Xinli Ye. "The preparation and research of reduced graphene oxide/glass composite fiber". Journal of Engineered Fibers and Fabrics 14 (gennaio 2019): 155892501988310. http://dx.doi.org/10.1177/1558925019883105.
Testo completoAbstract (sommario):
In this article, reduced graphene oxide/glass composite fiber was prepared from mixing graphene oxide and glass powder by ultrasonic dispersion, planetary grinding, high-temperature sintering, and melting wire drawing. The effects of reduced graphene oxide content on the mechanical and electrical properties of the fiber were investigated. Thermal gravimetric analyzer, differential scanning calorimeter, x-ray diffraction, and energy-dispersive x-ray spectroscopy analysis revealed that the graphene oxide was reduced to reduced graphene oxide in the sintering process and the performances of the composite fiber were improved. The tensile strength of reduced graphene oxide/glass composite fiber was 20% higher than the pristine glass fibers by the addition of 0.5 wt% of reduced graphene oxide. Reduced graphene oxide content was positively correlated with composites conductivity, and according to the percolation theory, the percolation threshold of reduced graphene oxide/glass composite fiber was about 0.5 wt%, and the conductivity of the composite fibers was increased by four orders of magnitude compared to the pristine glass fibers when the content of reduced graphene oxide was 0.5 wt%.
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Mardare, Andrei Ionut, Ivana Zrinski, Alexey Minenkov e Achim Walter Hassel. "Defect-Engineered Composite Hf-Ta Anodic Memristors for Reram Applications". ECS Meeting Abstracts MA2022-01, n. 29 (7 luglio 2022): 1296. http://dx.doi.org/10.1149/ma2022-01291296mtgabs.
Testo completoAbstract (sommario):
Various oxides and especially their modifications are in actual scientific focus for memristors fabrication due to their applications in non-volatile memories. Such devices exceed most limits of conventional memory technology. Memristors are recognized as resistive random access memories (ReRAMs), in which the data storage profits from a non-volatile change in the material resistance. The switching between a high resistance state (HRS) and a low resistance state (LRS) depends on the selection of electrodes and active (oxide) layers. This generally impacts the conductive pathways (filaments) formation, which is mediated by oxygen vacancies and/or cations, and their field-activated movement inside the oxide. Anodic oxides of valve metals (Al, Hf, Ta, Ti, Nb, Zr) have shown remarkable performances as memristive elements. Studies on Hf- and Ta-based memristors reported excellent electrical and memory properties, such as multi-level switching, high endurance and data retention. Even though for research purposes the synthesis of such oxide layers is commonly done by atomic layer deposition or sputtering, the electrochemical anodization process should not be neglected. This is a faster, less complex and inexpensive method, with precise composition and oxide thickness control through electrochemical parameters. The value of this approach is clearly emphasized by its continuous industrial implementation in various sectors. Previous works have confirmed that the performance of Hf or Ta anodic memristors can be improved by carefully selecting the anodization electrolyte or other electrochemical parameters1,2. These play a crucial role in positioning and sizing of conductive filaments within the oxide. This approach directly leads to defect-engineered memristors fabrication, which is nowadays a major motivation for investigating devices based on mixed oxides formed in different electrolytes. Predicting the position and shape/thickness of a conducting filament may eventually lead to enhanced device stability and resistive states control. The focus of the current work is on the behavior of anodic memristors based on ultra-thin Hf superimposed on Ta films. The main idea linked to the control of resistive filaments is based on the particularities of the anodization process, when the interface between both oxides is dynamically changing. In situ oxide self-nanostructuring is already known for various superimposed valve metals, including Hf and Ta. Their anodization leads to nanoscale oxide columns (“fingers”) formation, when a metal producing a more resistive oxide is superimposed on a metal producing a less resistive one. This phenomenon is recognized as an electrical version of the Rayleigh-Taylor effect and results from the ionic current preferring the less resistive paths, enhancing the growth of the correspondent oxide. Oxide resistivities and structures, transport numbers, Pilling-Bedworth ratios are all considered as determining factors for the anodization process of such superimposed systems. In the current work, anodization of Hf/Ta system leads to Rayleigh-Taylor effects since HfO2 is the more resistive oxide. The boundary between Hf and Ta oxides may influence the conductive pathways required for the memristive effect, thus being most relevant for fabrication of highly stable and forming-free memristors. Additionally, the use of superimposed films with gradient but complementary thicknesses allows investigating the ideal Hf/Ta ratios for which the best memristive behavior is obtained.3 From this study, one pronounced zone prominent for memristive applications is found for Hf/Ta thickness ratios between 4 and 5. Here, unipolar and bipolar memristors are identified, with remarkable endurance and retention capabilities. The CFs positioning is predefined by the development of Ta2O5 columnar structures grown during the anodization process. It is also possible that few CFs may be found in parallel, according to TEM observations, showing more than one Ta2O5 “finger”. Previous studies on pure Hf anodic memristors have confirmed concurrent competing CFs formation.2 Thus, one could assume that the memristive switching mechanism can be conditioned by the formation of oxides with such structures. The identified Hf/Ta ratio could be an excellent choice for improved memristors fabrication. Controlled O vacancies generation is a critical factor in switching uniformity and reproducibility. Therefore, oxide “fingers” formation is a promising electrochemical approach towards defect-engineered memristors. Further investigation of the composite oxide formation, particularly in Hf/Ta superimposed system, is topical. Until now, such systems were not recognized in the literature for the ReRAM applications. This is highly promising since both memory and electrical characteristics are improved by the forming-free nature of the memristors with CFs mediated by oxide nanostructuring. I. Zrinski et al., Nanomaterials 11, 1 (2021) https://doi.org/10.3390/nano11030666 I. Zrinski et al. Appl. Surf. Sci. 565, 150608 (2021) https://doi.org/10.1016/j.apsusc.2021.150608 I. Zrinski et al., J. Phys. Chem. Lett. 12, 8917 (2021) https://doi.org/10.1021/acs.jpclett.1c02346 Figure 1
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Kaya, Cengiz. "Current Status of Oxide Fibre-Reinforced Oxide Ceramic Matrix Composites for Gas Turbine Applications". Key Engineering Materials 434-435 (marzo 2010): 1–4. http://dx.doi.org/10.4028/www.scientific.net/kem.434-435.1.
Testo completoAbstract (sommario):
Recent developments in the processing, understanding and mechanical/thermomechanical properties of oxide fibre reinforced oxide ceramic matrix composites for high temperature applications are reported. Two dimensional composite plates and uni-directional tubular composite (so called mini-composite) specimens are successfully manufactured and their microstructure, matrix/ fiber interface as well as mechanical properties are examined. It is shown that the microstructural variations, such as porosity size and interface between fibre and matrix determine the fracture behaviour and high temperature performance of the composites. The optimised components produced are considered to be suitable for gas turbine applications.
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Seok, Dohyeong, Yohan Jeong, Kyoungho Han, Do Young Yoon e Hiesang Sohn. "Recent Progress of Electrochemical Energy Devices: Metal Oxide–Carbon Nanocomposites as Materials for Next-Generation Chemical Storage for Renewable Energy". Sustainability 11, n. 13 (5 luglio 2019): 3694. http://dx.doi.org/10.3390/su11133694.
Testo completoAbstract (sommario):
With the importance of sustainable energy, resources, and environmental issues, interest in metal oxides increased significantly during the past several years owing to their high theoretical capacity and promising use as electrode materials for electrochemical energy devices. However, the low electrical conductivity of metal oxides and their structural instability during cycling can degrade the battery performance. To solve this problem, studies on carbon/metal-oxide composites were carried out. In this review, we comprehensively discuss the characteristics (chemical, physical, electrical, and structural properties) of such composites by categorizing the structure of carbon in different dimensions and discuss their application toward electrochemical energy devices. In particular, one-, two-, and three-dimensional (1D, 2D, and 3D) carbon bring about numerous advantages to a carbon/metal-oxide composite owing to the unique characteristics of each dimension.
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Penialosa Ovalies, D. I., O. V. Boiprav, M. V. Tumilovich e L. M. Lynkou. "Electromagnetic radiation shielding composite coatings based on powdered alumina and ironoxide". Doklady BGUIR 19, n. 3 (2 giugno 2021): 104–9. http://dx.doi.org/10.35596/1729-7648-2021-19-3-104-109.
Testo completoAbstract (sommario):
The article presents the results of experimental substantiation of the method for improving the shielding properties of composite coatings based on powdered alumina (electrocorundum, alum earth), which consists in modifying the composition of such coatings by adding to it powdered iron oxide. This experimental substantiation consisted in the development of the technique for obtaining composite coatings based on powdered alumina and iron oxide, the manufacture of the experimental samplesusing the developed technique, measurements of electromagnetic radiation reflection and transmission coefficients values in the frequency range 0.7…17.0 GHz of the manufactured samples; implementation of the comparative analysis of the measured values with the similar values typical for the composite coatings filled with powdered alumina oxides, and composite coatings with the fillers such as powdered iron oxide. The obtained results revealed that by adding powdered iron oxide to the composite coatings based on powdered alumina oxides, it is possible to reduce by 1.0…8.0 dB their electromagnetic radiation transmission coefficient values in the frequency range 0.7…17.0 GHz. In addition, we found that the implementation of the proposed method allows one to decrease by 2.0…20.0 dB the electromagnetic radiation reflection coefficient values in the specified frequency range of the considered composite coatings, if such are applied to metal substrates. We propose to use the composite coatings, obtained on the base of the substantiated method, in order to ensure the electromagnetic compatibility of radio-electronic equipment.
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Ahadzade, Sh M., I. A. Vakulenko e Kh Asgarov. "Factors Influence on Electrophysical Parameters of the Composite Varistors". Science and Transport Progress, n. 1(101) (14 marzo 2023): 29–36. http://dx.doi.org/10.15802/stp2023/283013.
Testo completoAbstract (sommario):
Purpose. Evaluation influence structural state polymer phase on the response voltage and coefficient nonlinearity of a multilayer varistor based on zinc oxide. Methodology. Zinc oxide consisted of 97% zinc oxide and 3% total oxides of Bi2O3, Co3O4, MnO2, B2O3, SbO3, ZrO2, Al2O3. At a temperature of 1573°K, the synthesis of semiconductor ceramics based on Zinc oxide was carried out. For composite of thermoplastic polymers and Zinc oxide, non-polar and polar polymers, high pressure polyethylene and polyvinylidene fluoride were used. The composites were obtained by hot pressing at the melting temperature of the polymer phase and a pressure of 15 MPa. After that, using silver paste, measuring electrodes 10 mm in diameter were applied to the surface of the synthesized samples, and then current–voltage characteristics were measured. Modification of composites under action of gas-discharge plasma was carried out in a special cell that creates a dielectric-gas-composite system. The structure of the composites was studied by X-ray diffraction analysis and IR spectroscopy. Findings. The obtained experimental results show that the size of the particles of the inorganic phase significantly affects the current-voltage characteristics of the composite varistor: at a given thickness of the composite varistor, the operation voltage decreases markedly, and the nonlinearity coefficient increases. Numerous experimental results obtained by us show that the impact of electric discharge plasma on the polymer Zinc oxide-composite leads to a significant change in the permittivity and the concentration of local levels at the interface of the composite. The results research showed that effect electrical plasma on the opening voltage depends on the polarity of polymer matrices. Moreover, plasma processing itself significantly changes the structure of the polymer phase at composite. Originality. The magnitude of the potential barrier at phase boundary is mainly determined by the volume fraction and size of the main structural element of ZnO ceramics. Changing the structural state of the polymer matrix allows the adjust response voltage and coefficient nonlinearity of volt-ampere characteristic of the multilayer varistor. Practical value. The discovered development of electron-ion processes at polymer phase of the varistor indicates the need to take into account change in its service characteristics from the duration and intensity of use. The result obtained has a certain practical significance, since it indicates not only the reason for the change in properties, but also the need to develop measures to increase the service life of the varistor.
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Filho, Aureo Murador, Dayse Iara dos Santos, Marcos Yukio Kussuda, Camilla dos Santos Zanatta, Jae Geon Kim, Don Qui Shi e Shi Xie Dou. "ZnO-TiO2 Composite Formed by Mixed Oxides via Polyol". Materials Science Forum 727-728 (agosto 2012): 888–93. http://dx.doi.org/10.4028/www.scientific.net/msf.727-728.888.
Testo completoAbstract (sommario):
Among the researches on preparation and test of nanostructured materials, titanium dioxide and zinc oxide have been the most frequent studied oxides. In order to extend their properties, composites have been prepared using three different methods: Polyol Method, Sol-gel Process and a combination of the two processes (hybrid process). Recent research showed best properties in composite materials than in pure oxides. In this work is presented the preparation and the structural characterization of ZnO-TiO2 composite nanostructures to be tested for their performance in electrocatalysis and in further trial on photovoltaic cells.
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Yassaei, Soghra, Ali Nasr, Hengameh Zandi e Mohammad Nima Motallaei. "Comparison of antibacterial effects of orthodontic composites containing different nanoparticles on Streptococcus mutans at different times". Dental Press Journal of Orthodontics 25, n. 2 (marzo 2020): 52–60. http://dx.doi.org/10.1590/2177-6709.25.2.052-060.oar.
Testo completoAbstract (sommario):
ABSTRACT Introduction: Plaque accumulation can cause white spot lesions. Adding nanoparticles to composites can be effective in reducing the number and function of microorganisms. Objective: The aim of this study was to evaluate the antibacterial effects of orthodontic composites containing different nanoparticles on Streptococcus mutans at different times. Methods: Hydroxyapatite, titanium oxides, zinc oxide, copper oxide and silver oxide nanoparticles were prepared at 0.5% and 1% weight concentrations. Accordingly, ten study groups and one control group were obtained. Then, 26 composite discs were prepared from each group. Strain of Streptococcus mutans was cultured, and colonies of Streptococcus mutans were counted. Further bacterial culture was swapped onto enriched Mueller-Hinton agar. The composites were placed on the culture medium, and after incubation the diameter of growth inhibition was measured. To investigate the long-term effect of nanoparticles, the colonies were counted at days 3, 15 and 30. Results: The results showed that 1% copper oxide and 1% silver oxide significantly reduced the number of bacteria (p< 0.05), but there was no significant difference between the other groups and control group (p> 0.05). At day three, there was a significant difference between control group and 0.5% silver oxide, 1% silver oxide and 1% copper oxide groups (p< 0.05). However, colonies had grown in all groups at day 30 but showed no significant difference with control group (p> 0.05). Conclusion: Addition of 1% copper oxide and 1% silver oxide has short-term antibacterial effects, so the clinical use of these nanoparticles cannot be justified.
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Wu, Yali, Wenjie Hao, Tian Tian, Jinhe Yang e Yueping Cao. "Preparation of Graphene Doped Titanium Dioxide Compo -site and Study on Treatment of Laboratory Wastewater". International Journal of Materials Science and Technology Studies 1, n. 2 (30 maggio 2024): 1–11. http://dx.doi.org/10.62051/ijmsts.v1n2.01.
Testo completoAbstract (sommario):
In this paper, five kinds of composite materials were prepared by using graphene oxide (or graphene) doped with TiO2. The photocatalytic properties of five kinds of composite materials, pure graphene oxide and pure TiO2 for methyl orange, phenol solution and rhodamine B simulated laboratory wastewater were studied respectively. The experimental results show that the photocatalytic performance of graphene oxide-doped titanium dioxide composites is better than that of graphene oxide-doped titanium dioxide composites. When graphene oxide is doped with titanium dioxide as catalyst, the higher the purity of graphene oxide, the better the photocatalytic effect of the composite material. Doped titanium dioxide is better than undoped titanium dioxide. When the amount of doped titanium dioxide is 0.3g, the photocatalytic effect is the best. Based on the comprehensive data, it can be clearly found that graphene oxide doped TiO2 composite is more suitable for degrading rhodamine system. By simulating the treatment of laboratory wastewater, it lays a theoretical foundation for the treatment of laboratory wastewater in the future.
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Aubekerov, K., K. N. Punegova, R. Sergeenko, A. Kuznetsov, V. M. Kondratev, S. A. Kadinskaya, S. S. Nalimova e V. A. Moshnikov. "Synthesis and study of gas sensitive ZnFe2O4-modified ZnO nanowires". Journal of Physics: Conference Series 2227, n. 1 (1 marzo 2022): 012014. http://dx.doi.org/10.1088/1742-6596/2227/1/012014.
Testo completoAbstract (sommario):
Abstract Currently, new nanostructured materials based on composite metal oxides is of great interest for the development of gas sensors with improved functional characteristics. In this work, zinc oxide nanowires were synthesized by hydrothermal method. Hierarchical ZnO/ZnFe2O4 nanostructures were obtained by immersion of zinc oxide layers in ferrous sulphate aqueous solution. The mechanism of zinc ferrite formation during the interaction of zinc oxide with iron sulphate is considered. The crystal structure of ZnO and ZnO/ZnFe2O4 were studied by Raman spectroscopy. The sensitivity of ZnO and ZnO/ZnFe2O4 nanostructures to isopropyl alcohol vapors was analyzed. It was shown that there is an optimal concentration of ferrous sulphate used to modify zinc oxide nanowires and synthesize ZnO/ZnFe2O4 composite nanostructures.
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Huo, Jian Zhen. "Preparation of Composite Iron Oxides via Hydrothermal Process". Advanced Materials Research 583 (ottobre 2012): 162–66. http://dx.doi.org/10.4028/www.scientific.net/amr.583.162.
Testo completoAbstract (sommario):
Composite iron oxides are very important advanced materials. In this paper different types of iron oxides α-FeOOH, α-Fe2O3 and composite oxide NiFe2O4 were synthesized via a simple hydrothermal method at 180°C for 10 h. The phases and morphologies of the products were characterized by X-ray diffractometer and high-resolution transmission electron microscopy. The results indicated that α-FeOOH nanorods were prepared when mole concentration of NaOH solution was 3M. By increasing the concentration of NaOH to 5M and 8M, we obtained qusi-fusiform α-Fe2O3 single-crystallines and composite oxide NiFe2O4 nanocrystals, respectively. Our experiments showed that both the concentration of NaOH solution and existence of sulphate ions affect the formation of varying morphologies of the products.
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Chkhartishvili, Levan, Natia Barbakadze, Otar Tsagareishvili, Ketevan Sarajishvili, Tamar Korkia, Vakhtang Gabunia e Roin Chedia. "Coating of Carbon Black (CB) and Graphene Oxides (GOs) with Magnetite (Fe3O4)". International Journal of Advanced Nano Computing and Analytics 3, n. 1 (31 agosto 2024): 06–19. http://dx.doi.org/10.61797/ijanca.v3i1.330.
Testo completoAbstract (sommario):
Composites containing iron oxides are obtained by the co-precipitation of iron(II) and iron(III) compounds in the presence of different substrates in an alkaline environment. Newly synthesized graphene oxide (GO), reduced graphene oxide (rCO) and carbon black (CB) are used as substrates. Methods of obtaining GO–amorphous iron compound, rGO–Fe3O4, and CB–Fe3O4 composites are developed. It is determined that rGO–Fe3O4 and CB–Fe3O4 magnetic composites can be obtained at 70–75°C, while in the presence of GO, a non-magnetic composite containing an amorphous iron compound is formed under the same conditions. This composite, when heated in vacuum at 170–175°C, undergoes exfoliation, in result of which a powder composite rGO–amorphous iron compound is formed, the volume of which is 2.7 times greater than that of initial powder. Partial reduction of the formed composite takes place at 550°C and rGO–Fe3O4 is obtained. Formation of the magnetite phase is determined by XRD (X-Ray Diffraction) analysis. The structural-morphological study of the synthesized composites is carried out by the SEM (Scanning Electron Microscopy) method. Their magnetic characteristics are studied using VSM (Vibrating Sample Magnetometry) method.
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Rogacheva, A. O., O. S. Khalipova, A. S. Brichkov e V. V. Kozik. "Production of TiO2/Cr2O3 Composite Material in the Spherical Form". Herald of the Bauman Moscow State Technical University. Series Natural Sciences, n. 4 (85) (agosto 2019): 124–33. http://dx.doi.org/10.18698/1812-3368-2019-4-124-133.
Testo completoAbstract (sommario):
Spherical TiO2/Cr2O3 oxides composites were obtained by template method accompanied with sol-gel method. Ion exchange resins of spherical form (TOKEM-100 and TOKEM-250) were used as an organic polymer matrix. Thermal analysis, X-ray phase analysis and micro-X-ray spectral analysis were used to identify the formation process and compositions of oxides composites. The formation of spherical oxide composite ends at 400 °C and the final products are a mixture of two oxides: Cr2O3 and TiO2 regardless of the structure of the used template. According SEM data prepared TiO2/Cr2O3 composites have spherical form and the size of sphere found to be in a range from 300 to 870 µm.
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Evans, A. G., D. B. Marshall, F. Zok e C. Levi. "Recent advances in oxide-oxide composite technology". Advanced Composite Materials 8, n. 1 (gennaio 1999): 17–23. http://dx.doi.org/10.1163/156855199x00038.
Testo completo
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Huang, Wenjing, Tianyuan Yao, Qingli Hao, Wenjuan Wang, Xifeng Xia e Xin Wang. "Synthesis and electrochemical properties of graphene oxide/manganese oxide/polyaniline and its reduced composites". RSC Adv. 4, n. 100 (2014): 56615–24. http://dx.doi.org/10.1039/c4ra06360k.
Testo completo
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Zhang, Lei, Sha Xiangling, Zhang Lei, Huibin He, Yusu Wang, Zhenhua Ma e Yonghui Li. "Study on the Desulfurization Performance of N-Type and P-Type Semiconductor Pyrolysis Char Composite Catalyst". Journal of Environmental Science and Management 20, n. 1 (30 giugno 2017): 10–17. http://dx.doi.org/10.47125/jesam/2017_1/02.
Testo completoAbstract (sommario):
Ordos coal pyrolysis product roasted under 750oC was used as desulfurization sorbents to investigate the effect of flue gas desulfurization performance of supported metal catalyst. There were 14 kinds of metal oxides from groups IA, IIA, VIB, VIIB, VIII, IB and IIIB chosen as active components to prepare metal oxide supported catalysts by equivalent volume impregnation method. And the mechanism of pyrolysis was studied. The similarities of desulfurization performance among the same group of metal oxides were related to the structure of their outer electrons. In addtion, the influence of transition metal oxides on the desulfurization performance was related to metal oxide semiconductor type. Finally, the influence of the VIII group oxide catalyst of iron (Fe), Cobalt (Co), Nickel (Ni) on the desulfurization performance showed the characteristics of diversity related to their d percentage (%).
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Kim, Daeyoung, Heon Kang, Donghyun Bae, Seungjin Nam, Manuel Quevedo-Lopez e Hyunjoo Choi. "Synthesis of reduced graphene oxide/aluminum nanocomposites via chemical-mechanical processes". Journal of Composite Materials 52, n. 22 (21 febbraio 2018): 3015–25. http://dx.doi.org/10.1177/0021998318760152.
Testo completoAbstract (sommario):
The present study employed a combination of solution-based synthesis and mechanical milling to develop reduced graphene oxide/aluminum composites, in order to achieve uniform dispersion of reduced graphene oxide and strong interfaces between reduced graphene oxide and aluminum. First, spherical aluminum powder was flattened via mechanical milling to afford a large specific surface area and many reaction sites for the graphene oxide. A hydrophilic surface was then created by coating the aluminum powder with polyvinyl alcohol. The polyvinyl alcohol-coated aluminum slurry was mixed with a graphene oxide suspension, thereby inducing a reaction between graphene oxide and polyvinyl alcohol via hydrogen bonding. After thermal reduction, the composite powder was further ball milled and hot-pressed at 500℃ to produce a reduced graphene oxide/aluminum composite. The dispersion of reduced graphene oxide in the composite, as well as the mechanical and thermal behaviors of the composite, improved with increased flattening and specific surface area of the starting aluminum powder.
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Bugaeva, A. Yu, L. Yu Nazarova, E. M. Tropnikov, D. A. Shushkov, A. A. Utkin e Yu I. Ryabkov. "Preparation, microstructure and properties of ceramic composite based on stabilized zirconium oxide". Журнал общей химии 93, n. 11 (15 dicembre 2023): 1763–72. http://dx.doi.org/10.31857/s0044460x23110136.
Testo completoAbstract (sommario):
A pore-free ceramic composite [88ZrO2-11CeO2-Y2O3]/La0.85Y0.15Al11O18/Al2O3 with a matrix based on zirconium dioxide stabilized with cerium and yttrium oxides, filled with layered particles of lanthanum hexaaluminate and reinforced with aluminum oxide nanofibers, was obtained. The components of the composite were synthesized by the sol-gel method, with the exception of aluminum nanofibers obtained by electric explosion. The phase composition, microstructure and properties of the composite were studied depending on the combined influence of stabilizing additives and aluminum oxide nanofibers obtained by different methods. The composite is intended to be used as a ceramic material for structural and instrumental purposes.
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Thambiliyagodage, Charitha, Madara Jayanetti, Geethma Ekanayake, Amavin Mendis, Heshan Liyanaarchchi e Supuni Wijayawardana. "llmenite and Biomass Composite Nanomaterials - A Review". Catalysis Research 04, n. 02 (13 giugno 2024): 1–31. http://dx.doi.org/10.21926/cr.2402006.
Testo completoAbstract (sommario):
Ilmenite is a mineral whose crystallinity can be altered by chemical treatment, producing TiO<sub>2</sub> and iron and titanium-based metal nanocomposites, which are applicable mainly for photocatalysis. Porous and crystalline biomass-derived carbon materials include graphene oxide, reduced graphene oxide, graphitic carbon nitride, catalytically graphitized sucrose and chitosan, and activated carbon. Ilmenite-based metal oxides coupled with biomass-based carbon materials are effective in environmental remediation, especially in dye photodegradation, adsorption, and antibacterial activity. This review summarizes the synthesis and applications of ilmenite and biomass-based composites nanomaterials.
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Simsek, Tuncay, e Muharrem Pul. "The Effect of Ceramic Oxide Type on Compressive Strength and Abrasive Wear Behavior in Different Ceramic Oxide Reinforced Al2024 Composites". International Conference on Pioneer and Innovative Studies 1 (13 giugno 2023): 431–34. http://dx.doi.org/10.59287/icpis.868.
Testo completoAbstract (sommario):
In this study, particulate tungsten trioxide (WO3), Neodymium oxide (Nd2O3), zirconium oxide(ZrO2) and aluminum oxide (Al2O3) ceramics were separately reinforced at 10% weight ratio into 2024aluminum matrix material by powder metallurgy method. Abrasive wear and compression strength testswere carried out on the composite samples. According to the data obtained, the type of ceramic oxidereinforcement in the composite structure was compared according to the wear behavior and compressivestrength. As a result of the abrasive wear tests carried, the lowest wear loss amount was obtained from theAl2O3 reinforced composite, while the highest wear loss value was obtained from the WO3 reinforcedsample. Looking at the compressive strengths, it was seen that the highest compressive stress was obtainedfrom the Al2O3 reinforced composite, while the lowest compressive stress value was obtained from theNd2O3 reinforced sample. It was understood that the hardness values of the ceramic oxides doped into theAl2024 matrix directly affect the wear loss and compressive strength values of the composite structures. Itwas concluded that WO3, Nd2O3, ZrO2 and Al2O3 reinforcement elements in the form of particles dopedinto the Al2024 matrix improve the mechanical properties of the composite structure.
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Song, Liang, Mao Shan Niu e Yang Wang. "Cobalt Molybdate Incorporated Thermoset Composites: Preparation and Characterization". Key Engineering Materials 894 (27 luglio 2021): 31–37. http://dx.doi.org/10.4028/www.scientific.net/kem.894.31.
Testo completoAbstract (sommario):
Piezo-chromic oxides are able to mark pressure or strain by a drastic color change. In this paper, CoMoO4 molybdate compound and related thermoset composites were prepared in lab. The distribution of CoMoO4 oxide in the thermoset matrix was first investigated via SEM. Moreover, the effects on the thermal and mechanical properties with the addition of CoMoO4 oxide were further analyzed. The piezo-chromic characteristic for CoMoO4 incorporated thermoset composites were verified with compression test. The color change can be clear visualized at a strain level close to the yield point of the composite blends. This study has the potential to open new directions to piezo-chromic polymeric materials as early damage detector.
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Sarikov, Andrey. "Thermodynamic Theory of Phase Separation in Nonstoichiometric Si Oxide Films Induced by High-Temperature Anneals". Nanomanufacturing 3, n. 3 (3 luglio 2023): 293–314. http://dx.doi.org/10.3390/nanomanufacturing3030019.
Testo completoAbstract (sommario):
High-temperature anneals of nonstoichiometric Si oxide (SiOx, x < 2) films induce phase separation in them, with the formation of composite structures containing amorphous or crystalline Si nanoinclusions embedded in the Si oxide matrix. In this paper, a thermodynamic theory of the phase separation process in SiOx films is proposed. The theory is based on the thermodynamic models addressing various aspects of this process which we previously developed. A review of these models is provided, including: (i) the derivation of the expressions for the Gibbs free energy of Si oxides and Si/Si oxide systems, (ii) the identification of the phase separation driving forces and counteracting mechanisms, and (iii) the crystallization behavior of amorphous Si nanoinclusions in the Si oxide matrix. A general description of the phase separation process is presented. A number of characteristic features of the nano-Si/Si oxide composites formed by SiOx decomposition, such as the local separation of Si nanoinclusions surrounded by the Si oxide matrix; the dependence of the amount of separated Si and the equilibrium matrix composition on the initial Si oxide stoichiometry and annealing temperature; and the correlation of the presence of amorphous and crystalline Si nanoinclusions with the presence of SiOx (x < 2) and SiO2 phase, respectively, in the Si oxide matrix, are explained.
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Jiříčková, Adéla, Ondřej Jankovský, Zdeněk Sofer e David Sedmidubský. "Synthesis and Applications of Graphene Oxide". Materials 15, n. 3 (25 gennaio 2022): 920. http://dx.doi.org/10.3390/ma15030920.
Testo completoAbstract (sommario):
Thanks to the unique properties of graphite oxides and graphene oxide (GO), this material has become one of the most promising materials that are widely studied. Graphene oxide is not only a precursor for the synthesis of thermally or chemically reduced graphene: researchers revealed a huge amount of unique optical, electronic, and chemical properties of graphene oxide for many different applications. In this review, we focus on the structure and characterization of GO, graphene derivatives prepared from GO and GO applications. We describe GO utilization in environmental applications, medical and biological applications, freestanding membranes, and various composite systems.