Origin of Projected Excellent Thermoelectric Transport Properties in d 0 ‐Electron AMN 2 (A = Sr or Ba; M = Ti, Zr, Hf) Layered Complex Metal Nitrides

Layered materials have several properties that make them suitable as high‐performance thermoelectric materials. In this study, we elucidated the potential of d 0 ‐electron layered complex metal nitrides, AMN 2 (A = Sr or Ba; M = Ti, Zr, Hf), with KCoO 2 ‐type and α‐NaFeO 2 ‐type crystal structures. The detailed electronic structures and electronic transport coefficients for AMN 2 compounds were calculated by using density‐functional theory and Boltzmann theory, respectively. The KCoO 2 ‐type AMN 2 compounds show highly anisotropic thermoelectric properties. The effective masses at the lowest conduction bands in both KCoO 2 ‐type and α‐NaFeO 2 ‐type AMN 2 compounds were significantly smaller than that in three‐dimensional perovskite SrTiO 3 , a well‐known compound with good thermoelectric properties. The results suggest that the excellent thermoelectric transport properties arise from appropriate electronic structures and small effective masses in AMN 2 layered complex metal nitrides.