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185 results on '"Ostovari Moghaddam, Ahmad"'

24. Band-Gap Engineering of High-Entropy Fluorite Metal Oxide Nanoparticles Facilitated by Pr 3+ Incorporation by Gel Combustion Synthesis.

Author

Anandkumar, Mariappan, Kesavan, Kannan Pidugu, Sudarsan, Shanmugavel, Zaitseva, Olga Vladimirovna, Ostovari Moghaddam, Ahmad, Iarushina, Daria Valerevna, and Trofimov, Evgeny Alekseevich

Subjects
SELF-propagating high-temperature synthesis, FIELD emission electron microscopy, METAL nanoparticles, METALLIC oxides, PHASE separation
Abstract

Tailoring the bandgap of a material is necessary for improving its optical properties. Here, the optical bandgap of high-entropy oxide Ce0.2Gd0.2Sm0.2Y0.2Zr0.2O2-δ (HEO) nanoparticles was modified using Pr3+. Various concentrations of Pr3+ (x = 0, 0.01, 0.02, 0.05, 0.075, 0.1, 0.15) were incorporated into the host high-entropy oxide using a gel combustion synthesis. After the gel combustion step, the powders were heat-treated at various temperatures (650 °C, 800 °C, 950 °C) for 2 h. The obtained Pr3+-incorporated HEO powders were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and UV–visible spectroscopy. The results indicate that, when the samples are calcined at 950 °C, a single-phase cubic fluorite structure is obtained without any phase separation or impurity. The optical absorbance red-shifts to higher wavelengths when the concentration of Pr3+ is increased. This reduces the bandgap of the material from 3.15 eV to 1.87 eV for Pr3+ concentrations of x = 0 (HEO-0) and x = 0.15 (HEO-6), respectively. The obtained HEOs can be suitable candidates for photocatalytic applications due to their absorbance in the visible region. [ABSTRACT FROM AUTHOR]

Published
2025
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36. Advancements in joining Al-Zn-TiC-Mg composites using friction stir welding process: Influence of traverse speed.

Author

Abdollahzadeh, Amin, Bagheri Vanani, Behrouz, Masoudi Morghmaleki, Abbas, Ostovari Moghaddam, Ahmad, and Eivani, Ali Reza

Subjects
ALUMINUM alloy welding, FRICTION stir welding, INTERMETALLIC compounds, MAGNESIUM alloys, RECRYSTALLIZATION (Metallurgy)
Abstract

In this article, dissimilar magnesium and aluminum alloys were welded with a Zn interlayer and TiC nanoparticles by friction stir welding. Optimal joining conditions were achieved by a combination of three traverse speeds (30, 45, and 60 mm/min) and constant rotational speeds (1050 rpm). The best microstructure evolution and mechanical properties were achieved for specimens joined at rotational and traverse speeds of 1050 rpm and 45 mm/min, respectively. The grain size decreases as the traverse speed increases from 30 to 45 mm/min due to a reduction in heat input, an improvement in reinforcing distribution, and high intermixing of materials, then increases from 45 to 60 mm/min due to inadequate heat input for recrystallization process. It was shown that the TiC particles play a prominent role in the microstructure modification and enhance mechanical properties of weld samples while the Zn foil interlayer plays a vital in avoiding the formation of Al-Mg IMC phases. The obtained result under optimal welding parameters indicates that MgZn2, Mg-Al-Zn compounds, Mg and Al solid solution, were the main detected common phases in the stir zone instead of the brittle and hard Al-Mg IMCs formation. The average hardness values of 232 Hv were achieved, while the strength of the weld specimen experiences the 189 MPa value. In addition, a combination of brittle and ductile modes was observed based on the fracture surface of the weld sample after the tensile test. [ABSTRACT FROM AUTHOR]

Published
2024
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39. The Behavior of Al0.5CoCrFeNiCuPt0.3 High-Entropy Alloy During High-Temperature Oxidation.

Author

Samoilova, Olga, Suleymanova, Ilsiya, Shaburova, Nataliya, Ostovari Moghaddam, Ahmad, and Trofimov, Evgeny

Subjects
PLATINUM alloys, JET engines, TURBOJET engines, OXIDATION, MACHINE parts, PLATINUM
Abstract

The quest for high-entropy alloys (HEAs) with superior resistance against oxidation at elevated temperatures is one of the urgent problems in materials society, since HEAs are candidates for coating machinery parts operating in aggressive conditions (such as turbine blades, turbojet and jet engines, etc.). In this study, the effect of minor platinum alloying on the microstructure, phase composition and high-temperature oxidation resistance of Al0.5CoCrFeNiCuPt0.3 HEA was studied. It was demonstrated that platinum does not precipitate as an intermetallic phases; rather, it dissolves in the solid solution phases. High-temperature oxidation tests were carried out in a muffle furnace at 900 °C and 1000 °C for 50 h in air. It was found out that platinum alloying significantly increases oxidation resistance of Al0.5CoCrFeNiCuPt0.3 HEA at elevated temperatures with specific weight change of 0.139 mg/cm2 and 0.238 mg/cm2 after 50 h of isothermal exposure to 900 °C and 1000 °C, respectively. A dense oxide layer, mainly composed of Al2O3, without defects and pores protected the surface of the alloy. [ABSTRACT FROM AUTHOR]

Published
2024
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45. A 3d‐4d‐5d High Entropy Alloy as a Bifunctional Oxygen Catalyst for Robust Aqueous Zinc–Air Batteries

Author

He, Ren, primary, Yang, Linlin, additional, Zhang, Yu, additional, Jiang, Daochuan, additional, Lee, Seungho, additional, Horta, Sharona, additional, Liang, Zhifu, additional, Lu, Xuan, additional, Ostovari Moghaddam, Ahmad, additional, Li, Junshan, additional, Ibáñez, Maria, additional, Xu, Ying, additional, Zhou, Yingtang, additional, and Cabot, Andreu, additional

Published
2023
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48. Supporting information A CrMnFeCoNi high entropy alloy boosting oxygen evolution/reduction reactions and zinc-air battery performance

Author

Xu, Ying [xuying@hbu.edu.cn], Cabot, Andreu [acabot@irec.cat], He, Ren, Yang, Linlin, Zhang, Yu, Wang, Xiang, Lee, Seung-Ho, Zhang, Ting, Li, Lingxiao, Liang, Zhifu, Chen, Jingwei, Li, Junshan, Ostovari Moghaddam, Ahmad, Llorca, Jordi, Ibáñez, María, Arbiol, Jordi, Xu, Ying, Cabot, Andreu, Xu, Ying [xuying@hbu.edu.cn], Cabot, Andreu [acabot@irec.cat], He, Ren, Yang, Linlin, Zhang, Yu, Wang, Xiang, Lee, Seung-Ho, Zhang, Ting, Li, Lingxiao, Liang, Zhifu, Chen, Jingwei, Li, Junshan, Ostovari Moghaddam, Ahmad, Llorca, Jordi, Ibáñez, María, Arbiol, Jordi, Xu, Ying, and Cabot, Andreu

Published
2023

49. A CrMnFeCoNi high entropy alloy boosting oxygen evolution/reduction reactions and zinc-air battery performance

Author

Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Generalitat de Catalunya, Ministerio de Ciencia e Innovación (España), European Commission, Universidad de Barcelona, Institute of Science and Technology (Austria), Werner Siemens Foundation, China Scholarship Council, National Key Research and Development Program (China), Natural Science Foundation of Sichuan Province, He, Ren, Yang, Linlin, Zhang, Yu, Wang, Xiang, Lee, Seung-Ho, Zhang, Ting, Li, Lingxiao, Liang, Zhifu, Chen, Jingwei, Li, Junshan, Ostovari Moghaddam, Ahmad, Llorca, Jordi, Ibáñez, María, Arbiol, Jordi, Xu, Ying, Cabot, Andreu, Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Generalitat de Catalunya, Ministerio de Ciencia e Innovación (España), European Commission, Universidad de Barcelona, Institute of Science and Technology (Austria), Werner Siemens Foundation, China Scholarship Council, National Key Research and Development Program (China), Natural Science Foundation of Sichuan Province, He, Ren, Yang, Linlin, Zhang, Yu, Wang, Xiang, Lee, Seung-Ho, Zhang, Ting, Li, Lingxiao, Liang, Zhifu, Chen, Jingwei, Li, Junshan, Ostovari Moghaddam, Ahmad, Llorca, Jordi, Ibáñez, María, Arbiol, Jordi, Xu, Ying, and Cabot, Andreu

Abstract

The development of cost-effective, high-activity and stable bifunctional catalysts for the oxygen reduction and evolution reactions (ORR/OER) is essential for zinc–air batteries (ZABs) to reach the market. Such catalysts must contain multiple adsorption/reaction sites to cope with the high demands of reversible oxygen electrodes. Herein, we propose a high entropy alloy (HEA) based on relatively abundant elements as a bifunctional ORR/OER catalyst. More specifically, we detail the synthesis of a CrMnFeCoNi HEA through a low-temperature solution-based approach. Such HEA displays superior OER performance with an overpotential of 265 mV at a current density of 10 mA/cm2, and a 37.9 mV/dec Tafel slope, well above the properties of a standard commercial catalyst based on RuO2. This high performance is partially explained by the presence of twinned defects, the incidence of large lattice distortions, and the electronic synergy between the different components, being Cr key to decreasing the energy barrier of the OER rate-determining step. CrMnFeCoNi also displays superior ORR performance with a half-potential of 0.78 V and an onset potential of 0.88 V, comparable with commercial Pt/C. The potential gap (Egap) between the OER overpotential and the ORR half-potential of CrMnFeCoNi is just 0.734 V. Taking advantage of these outstanding properties, ZABs are assembled using the CrMnFeCoNi HEA as air cathode and a zinc foil as the anode. The assembled cells provide an open-circuit voltage of 1.489 V, i.e. 90% of its theoretical limit (1.66 V), a peak power density of 116.5 mW/cm2, and a specific capacity of 836 mAh/g that stays stable for more than 10 days of continuous cycling, i.e. 720 cycles @ 8 mA/cm2 and 16.6 days of continuous cycling, i.e. 1200 cycles @ 5 mA/cm2.

Published
2023

50. (CoFeMnCuNiCr)3O4 High-Entropy Oxide Nanoparticles Immobilized on Reduced Graphene Oxide as Heterogeneous Catalysts for Solvent-Free Aerobic Oxidation of Benzyl Alcohol.

Author

Mehrabi-Kalajahi, Seyedsaeed, Ostovari Moghaddam, Ahmad, Hadavimoghaddam, Fahimeh, Salari, Rana, Varfolomeev, Mikhail A., Zinnatullin, Almaz L., Minnebaev, Kamil R., Emelianov, Dmitrii A., Uchaev, Daniil A., Fereidonnejad, Rahele, Zaitseva, Olga, Khasanova, Gulgena R., Trofimov, Evgeny A., Rozhenko, Alexei, Cabot, Andreu, and Vagizov, Farit G.

Abstract

The development of noble metal-free heterogeneous catalysts holds promise for the solvent-free and selective aerobic oxidation of organic compounds. However, the moderate activity of these catalysts under atmospheric conditions limits their industrial use. In this work, the synthesis of noble metal-free (CoFeMnCuNiCr)3O4 high-entropy oxide (HEO) nanoparticles and their grafting on reduced graphene oxide (rGO) to produce a HEO–rGO nanocomposite is detailed. X-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman and Mössbauer spectroscopy analyses confirm the formation of the spinel HEO phase. HEO–rGO nanocomposites are used for aerobic and solvent-free oxidation of benzyl alcohol, displaying excellent catalytic performance. Up to 10.36% conversion and 78.5% selectivity of benzaldehyde can be achieved in only 4 h. An extensive analytical study shows that the excellent performance of HEO–rGO nanocomposites is attributed to the synergistic effect between the rGO active sites and the abundant oxygen vacancies within the HEO nanoparticles. Moreover, four robust machine learning models including Adaptive Boosting (AdaBoost), Categorical Boosting (CatBoost), Random Forest (RF), and eXtreme Gradient Boosting (XGBoost) are applied to predict the selectivity of the oxidation reactions. The XGBoost is demonstrated as the best-fitting model for all data with an error of less than 2.5%. Overall, both experimental and numerical data suggest the potential application of the HEO–rGO nanocomposites in chemical industries for the selective oxidation of alcohols to added-value products. [ABSTRACT FROM AUTHOR]

Published
2024
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