Anisotropic thermoelectric properties in layered complex nitrides with α-NaFeO2-type structure

Isao Ohkubo,Takao Mori

doi:10.1063/1.4955399

Abstract

Electronic structures and thermoelectric transport properties of α-NaFeO2-type d0-electron layered complex nitrides AMN2 (A = Sr or Na; M = Zr, Hf, Nb, Ta) were evaluated using density-functional theory and Boltzmann theory calculations. Despite the layered crystal structure, all materials had three-dimensional electronic structures. Sr(Zr, Hf)N2 exhibited isotropic electronic transport properties because of the contribution of the Sr 4d orbitals to the conduction band minimums (CBMs) in addition to that of the Zr 4d (Hf 5d) orbitals. Na(Nb,Ta)N2 showed weak anisotropic electronic transport properties due to the main contribution of the Nb 4d (Ta 5d) and N 2p orbitals to the CBMs and no contribution of the Na orbitals.

Highlights

Anisotropic thermoelectric properties in layered complex nitrides with α-NaFeO2-type structure
Electronic structures and thermoelectric transport properties of α-NaFeO2-type d0electron layered complex nitrides AMN2 (A = Sr or Na; M = Zr, Hf, Nb, Ta) were evaluated using density-functional theory and Boltzmann theory calculations
Na(Nb,Ta)N2 showed weak anisotropic electronic transport properties due to the main contribution of the Nb 4d (Ta 5d) and N 2p orbitals to the conduction band minimums (CBMs) and no contribution of the Na orbitals

Summary

Introduction

Anisotropic thermoelectric properties in layered complex nitrides with α-NaFeO2-type structure Isao Ohkubo1,2,3,a and Takao Mori1 1WPI Research Center, International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan 2Information Integrated Materials Research Unit, Research Center for Information Integrated Materials, NIMS, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan 3JST-PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan (Received 28 April 2016; accepted 24 June 2016; published online 7 July 2016)

Results

Conclusion