Metallic n-Type Mg3Sb2 Single Crystals Demonstrate the Absence of Ionized Impurity Scattering and Enhanced Thermoelectric Performance

Imasato K, Fu C, Pan Y, Wood M, Kuo JJ, Felser C, Snyder GJ (2020)

Publication Type: Journal article

Publication year: 2020

Journal

Advanced Materials Wiley

Book Volume: 32

Article Number: 1908218

Journal Issue: 16

DOI: 10.1002/adma.201908218

Abstract

Mg3(Sb,Bi)2 alloys have recently been discovered as a competitive alternative to the state-of-the-art n-type Bi2(Te,Se)3 thermoelectric alloys. Previous theoretical studies predict that single crystals Mg3(Sb,Bi)2 can exhibit higher thermoelectric performance near room temperature by eliminating grain boundary resistance. However, the intrinsic Mg defect chemistry makes it challenging to grow n-type Mg3(Sb,Bi)2 single crystals. Here, the first thermoelectric properties of n-type Te-doped Mg3Sb2 single crystals, synthesized by a combination of Sb-flux method and Mg-vapor annealing, is reported. The electrical conductivity and carrier mobility of single crystals exhibit a metallic behavior with a typical T−1.5 dependence, indicating that phonon scattering dominates the charge carrier transport. The absence of any evidence of ionized impurity scattering in Te-doped Mg3Sb2 single crystals proves that the thermally activated mobility previously observed in polycrystalline materials is caused by grain boundary resistance. Eliminating this grain boundary resistance in the single crystals results in a large enhancement of the weighted mobility and figure of merit zT by more than 100% near room temperature. This work experimentally demonstrates the accurate understanding of charge-carrier scattering is crucial for developing high-performance thermoelectric materials and indicates that single-crystalline Mg3(Sb,Bi)2 solid solutions can exhibit higher zT compared to polycrystalline samples.

Involved external institutions

Max-Planck-Institut für Chemische Physik fester Stoffe (MPI CPfS) / Max Planck Institute for Chemical Physics of Solids DE Germany (DE) Northwestern University US United States (USA) (US)

How to cite

APA:

Imasato, K., Fu, C., Pan, Y., Wood, M., Kuo, J.J., Felser, C., & Snyder, G.J. (2020). Metallic n-Type Mg3Sb2 Single Crystals Demonstrate the Absence of Ionized Impurity Scattering and Enhanced Thermoelectric Performance. Advanced Materials, 32(16). https://doi.org/10.1002/adma.201908218

MLA:

Imasato, Kazuki, et al. "Metallic n-Type Mg3Sb2 Single Crystals Demonstrate the Absence of Ionized Impurity Scattering and Enhanced Thermoelectric Performance." Advanced Materials 32.16 (2020).

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