Dislocation-induced ultra-low lattice thermal conductivity in rare earth doped β-Zn4Sb3

Abstract

Defect engineering in thermoelectric materials leads to the formation of exotic transport properties. Specifically, reduction in lattice thermal conductivity (кL) can be realized through scattering of low and high-frequency phonons by interfacial and point defects respectively. Herein we explore such phenomena by inducing dense dislocations through doping of rare earth (RE) impurities in β-(Zn1−xREx)4Sb3 [x = 0.3–0.5 at.%] as phonon scattering source of all frequencies. Lattice anharmonicity created results in an ultra-low кL of ~0.15 W/mK for β-(Zn0.997 Yb0.003)4Sb3. Vibrational properties and phonon scattering altered by the lattice anharmonicity are studied in detail through terahertz and infrared spectroscopies.