Systematic investigation on transverse thermoelectric conversion of RE ₂ (Fe,Co) ₁₄ B (RE = rare-earth) compounds

Transverse thermoelectric generation (TEG) based on the anomalous Nernst effect (ANE) is a promising technology capable of converting waste heat into electricity. The transverse TEG device can operate without applying an external magnetic field by implementing permanent magnets, such as Nd2Fe14B-type magnets. However, the transverse thermoelectric properties of the rare-earth (RE) based compounds have not been systematically studied and understood so far. In this work, we have explored the potential of RE2Fe14B and Nd2(Fe, Co)14B compounds and systematically investigated the transverse thermoelectric properties at room temperature. We obtained the negative anomalous Nernst coefficient (SANE) for all the RE2Fe14B (RE=Tb, Dy, Ho, and Nd) alloys regardless of the RE element and the highest negative SANE of -0.67× 10−6 VK−1 for Tb2Fe14B among them, which is comparable to that of the commercial Nd2Fe14B permanent magnets with an optimized microstructure. The substitution of Co for Fe site in Nd2(Fe1-pCop)14B alloys causes sign reversal (from negative to positive) of SANE values. The transverse thermoelectric conductivity is responsible for the sign change in SANE values. As a result, the Nd2(Fe0.4Co0.6)14B alloy shows the highest positive SANE of 1.87 × 10−6 VK−1, revealing that the RE and 3d transition metal elements play the distinct roles on the transverse thermoelectric performance in RE2(Fe,Co)14B compounds.