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Open AccessArticle

Exploration of the Reduction Diffusion Temperature for Different Phases of Samarium–Cobalt Magnetic Particles

by Yani Lu, Xiangyu Ma, Jinping Ren, Jinke Kang and Yatao Wang

Molecules 2025, 30(9), 1975; https://doi.org/10.3390/molecules30091975 - 29 Apr 2025

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We report a method for synthesizing different phases of samarium–cobalt particles through microwave-assisted combustion combined with high-temperature reduction and diffusion, and identify the optimal temperature for forming the 1:5 phase using this approach. Initially, the samarium-to-cobalt ratio in a nitrate solution was determined. Using urea as both a reductant and fuel, samarium–cobalt oxides were synthesized via microwave-assisted combustion. The main components of the oxides were confirmed to be SmCoO₃ and Co₃O₄. Subsequently, samarium–cobalt particles were synthesized at various diffusion temperatures. The results indicate that at 700 °C, the oxides were reduced to elemental Sm and Co. As the reduction temperature increased, the alloying of samarium and cobalt occurred, and the particle size gradually increased. At 900 °C, a pure 1:5 phase was formed, with particle sizes of approximately 800 nm, a coercivity of 35 kOe, and a maximum energy product of 14 MGOe. Based on the microwave-assisted combustion method, this study clarifies the transition temperatures of samarium–cobalt phases during the reduction and diffusion process, and further establishes the synthesis temperature for the 1:5 phase, providing new insights into the preparation and development of samarium–cobalt materials and potentially other rare earth materials. Full article

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19 pages, 9959 KB

Open AccessFeature PaperArticle

A New Approach to the Preparation of Stable Oxide-Composite Cobalt–Samarium Catalysts for the Production of Hydrogen by Dry Reforming of Methane

by A. G. Dedov, A. S. Loktev, V. A. Arkhipova, M. A. Bykov, A. A. Sadovnikov, K. A. Cherednichenko and G. A. Shandryuk

Processes 2023, 11(8), 2296; https://doi.org/10.3390/pr11082296 - 31 Jul 2023

Cited by 2 | Viewed by 1543

Abstract

A new approach to preparing a series of Co/Sm₂O₃ catalysts for hydrogen production by the dry reforming of methane has been developed. The catalyst precursors were synthesized with a simple method, including the evaporation of aqueous solutions of cobalt and samarium nitrates, followed by a short-term calcination of the resulting material. The as-prepared and spent catalysts were characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, temperature-programmed reduction, and thermogravimetric analysis. The content of cobalt in the synthesized materials affects their phase composition and carbonization resistance in the dry reforming of the methane reaction. It has been shown that preheating in N₂ atmosphere produces catalysts that provide a stable yield of hydrogen and CO of 94–98% for at least 50 h at 900 °C. These yields are among the highest currently available for the dry reforming of methane catalysts made from Co-Sm complex oxides. It has been established that the decrease in the amount of cobalt in the catalyst and its preheating to an operating temperature of 900 °C in a nitrogen flow help to prevent the carbonization of the catalyst and the sintering of metal particles. Full article

(This article belongs to the Special Issue Hydrogen Production and Purification)

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