Magnetic Properties of Mechanically Milled Sm-Co Permanent Magnetic Materials with the TbCu7 Structure

Raphael Justin Joseyphus; Alwarramanujam Narayanasamy; Raghavan Gopalan; Venkatasubramanian Chandrasekaran; Balachandran Jeyadevan; Kazuyuki Tohji

doi:10.2320/matertrans.47.2264

Magnetic Properties of Mechanically Milled Sm-Co Permanent Magnetic Materials with the TbCu₇ Structure

Raphael Justin Joseyphus, Alwarramanujam Narayanasamy, Raghavan Gopalan, Venkatasubramanian Chandrasekaran, Balachandran Jeyadevan, Kazuyuki Tohji

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Keywords: Dipolar coupling, permanent magnetic materials, mechanical milling, TbCu₇ structure

JOURNAL FREE ACCESS

2006 Volume 47 Issue 9 Pages 2264-2268

DOI https://doi.org/10.2320/matertrans.47.2264

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Abstract

The magnetic properties of Sm(Co,Fe,Cu,Zr)₇ compound with the TbCu₇ structure are studied for the mechanically milled samples. The coercivity could be varied, without affecting the saturation magnetization, from 44 kA/m for the micron sized particles to 280 kA/m by reducing the particle size to sub-micron size (600–900 nm) using high-energy ball milling. The enhancement in the coercivity is attributed to the particles approaching single domain size. The presence of dipolar coupling suggests that the grain sizes are well above the exchange length for the milled samples. The thermal measurements indicate that the compound with the TbCu₇ structure is not stable at high temperatures beyond 743 K.

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