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In-Situ Tem Dynamic Magnetizing Experiments Used To Identify The Pinning Centers In Hard Magnets Re13.75fe80.25b6 (Re=Nd, Pr).

Published online by Cambridge University Press:  02 July 2020

V.V. Volkov  and
Y. Zhu
V.V. Volkov
Affiliation:
Department of Applied Science, Brookhaven National Laboratory, Upton, NY11973
Y. Zhu
Affiliation:
Department of Applied Science, Brookhaven National Laboratory, Upton, NY11973
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Extract

The new JEOL 3000F high resolution electron microscope at BNL has been optimized for Lorentz imaging. The necessary field-free environment around the sample is obtained by switching off the objective lens in the free-lens control mode, and the associated reduction in magnification is compensated for by a Gatan post-column image filter (GIF) at ∼ 20x magnification. Fresnel imaging is obtained by defocusing with objective mini-lens (OM). The use of low angle diffraction with an aperture located at the back focal plane makes it possible to obtain Foucault images.

In-situTEM dynamic magnetizing experiments combined with Lorentz magnetrc microscopy both in Fresnel and Foucault modes were used to characterize the magnetic structure of some hard and relatively soft magnets, Nd13.75Fe80.25B6 and Pr13.75Fe80.25B6, prepared by different processing routes. The goal of these in-situexperiments was to develop a reliable and effective procedure to search for, identify, and classify the different pinning centers present in real magnets that accord with their “pinning power” versus applied magnetic field.

Type
Magnetic Imaging And Its Application To Materials
Information
Microscopy and Microanalysis , Volume 5 , Issue S2: Proceedings: Microscopy & Microanalysis '99, Microscopy Society of America 57th Annual Meeting, Microbeam Analysis Society 33rd Annual Meeting, Portland, Oregon August 1-5, 1999 , August 1999 , pp. 20 - 21
Copyright
Copyright © Microscopy Society of America

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References

1.)Volkov, V.V., Crew, D.C., Zhu, Y., Lewis, L.H., “Magnetic Field Calibration of the JEOL 3000FEG Electron Microscope: Application to Studies of Hard Magnets”(See the same Proceedings MSA'99)Google Scholar
2.)Work supported by US DOE, under contract No. DE-AC02-98CH10886.Google Scholar