Tripling magnetite's thermoelectric figure of merit with rare earth doping

KS Suraj and HA Eivari and G Tatara and MHN Assadi, JOURNAL OF MATERIALS CHEMISTRY C, 12, 19212-19218 (2024).

DOI: 10.1039/d4tc03153a

Using density functional theory (DFT) and machine-learning force fields, we calculated the thermoelectric properties of magnetite doped with four rare-earth elements: lanthanum, cerium, praseodymium, and neodymium. Our results show that Fe3O4:Nd3+ exhibits the highest power factor (PF) of 6294 mu W m-1 K-2 at 300 K when hole-doped at a concentration of 1021 cm-3. This remarkably high PF surpasses those reported in the literature for binary oxides and is a significant improvement upon the PF of pristine Fe3O4, which was calculated to be less than 4600 mu W m-1 K-2 over a temperature range between 300 K and 900 K. More importantly, we predict a maximum thermoelectric figure of merit (ZT) of 0.76 at 800 K for Fe3O4:Nd3+, nearly triple the ZT of pristine Fe3O4 at the same temperature, with a 191.2% improvement. Our calculations offer a theoretical analysis of realistic expectations for thermoelectric enhancement by heavy but isovalent dopants in magnetic oxides, as Nd adopts a +3 oxidation state, being isovalent to the Fe it replaces, and is about three times heavier than Fe. Using density functional theory (DFT) and machine-learning force fields, we calculated the thermoelectric properties of magnetite doped with four rare-earth elements: lanthanum, cerium, praseodymium, and neodymium.

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