A 59Co NMR study to observe the effects of ball milling on small ferromagnetic cobalt particles

Speight, R.; Wong, Alan; Ellis, Peter R.; Hyde, Timothy I.; Bishop, P J; Smith, Mark E.

doi:10.1016/j.ssnmr.2008.12.001

Cited by 8 publications

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References 35 publications

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“…In ref. [ 43 ], the appearance of a shoulder extended to low frequencies was associated with an increase in the number of grain boundaries, which occurred due to particle fracturing during mechanical activation of pure metallic cobalt. In the same work, a similar change in the ratio of the fcc and hcp lines, associated with an increase in the defect concentration in the particles, was observed.…”

Section: Resultsmentioning

confidence: 99%

Formation of Metal-Oxide Nanocomposites with Highly Dispersed Co Particles from a Co-Zr Powder Blend by Mechanical Alloying and Hydrogen Treatment

et al. 2023

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The use of metal powders produced by mechanical treatment in various fields, such as catalysis or gas absorption, is often limited by the low specific surface area of the resulting particles. One of the possible solutions for increasing the particle fineness is hydrogen treatment; however, its effect on the structure of mechanically treated powders remains unexplored. In this work, for the first time, a metal-oxide nanocomposite powder was produced by mechanical alloying (MA) in a high-energy planetary ball mill from commercial powders of Zr and Co in the atomic ratio Co:Zr = 53:47 in an inert atmosphere, followed by high-pressure hydrogenation at room temperature. The initial powders and products of alloying and hydrogenation were studied by XRD, 59Co Internal Field NMR, SEM, and HRTEM microscopy with EDX mapping, as well as Raman spectroscopy. MA resulted in significant amorphization of the powders, as well as extensive oxidation of zirconium by water according to the so-called “Fukushima effect”. Moreover, an increase in hcp Co sites was observed. 59Cо IF NMR spectra revealed the formation of magnetically single-domain cobalt particles after hydrogenation. The crystallite sizes remained unchanged, which was not observed earlier. The pulverization of Co and an increase in hcp Co sites made this nanocomposite suitable for the synthesis of promising Fischer–Tropsch catalysts.

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Section: Resultsmentioning

confidence: 99%