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Kautsar et al. Energy Mater. 2025, 5, 500129 https://dx.doi.org/10.20517/energymater.2025.26 Page 11 of 14

Figure 7. (A) Seebeck coefficient (S ); (B) µ H dependence of Hall resistivity (ρ ); (C) contributions of S and S to the S ; and (D)
xx 0 yx I II ANE
transverse thermoelectric conductivity (α ) for the studied magnets. S ANE : Anomalous nernst coefficient.
xy
demonstrated in ref. [28,61] . On the other hand, a systematic investigation of microstructural features beyond
the crystallinity of the IGP, including grain size, shape, IGP thickness, and IGP continuity is still needed to
understand how they impact the S and S components. Although the S of the magnets studied in this
II
ANE
I
research is still lower than that of commercial sintered magnets reported in previous work , as shown in
[27]
Supplementary Figure 6, this study has demonstrated that optimizing the microstructure can effectively
increase both S and z T in Nd-Fe-B magnets, paving the way for further advancements in magnet
ANE
ANE
optimization for TEG applications.
CONCLUSIONS
This study addresses a gap in the understanding of how microstructural features can influence the σ , κ,
xx
and S in the Nd-Fe-B permanent magnets fabricated from rapidly solidified ribbon powders, offering
ANE
-7
-1
insights into improving S . The findings reveal that S increases by 68%, from -2.6 × 10 VK in the HP
ANE
ANE
state to -4.4 × 10 VK after HD in which grain growth and crystallographic texture are realized without
-7
-1
changing the composition of the magnets. S further increases to -5.0 × 10 VK after grain boundary
-1
-7
ANE
structure and composition change from thin amorphous phase to thick crystalline phase by grain boundary
diffusion of Dy-Nd-Cu alloy. The increase in S is primarily due to the reduction of the opposing S II
ANE
component following HD and GBDP. Owing to the crystallographic texture formation after HD, almost the
same transverse thermopower as S is obtained in HD and RE-Cu (RE = Dy-Nd, Nd, and Pr) GBDP
ANE
Nd-Fe-B magnets at the M state (zero H). However, the enhancement in S following GBDP is somewhat
r
ANE
counterbalanced by the increase in κ, resulting in a smaller improvement in z T. These findings
ANE
demonstrate that microstructural optimization can effectively enhance the S in ultra-fine grained
ANE
Nd-Fe-B magnets, providing a promising avenue for advancing materials in applications of transverse