Low lattice thermal conductivity and high figure of merit in n‐type doped full‐Heusler compounds X ₂ YAu (X = Sr, Ba; Y = as, Sb)

Abstract

As a new type of thermoelectric (TE) material, full-Heusler compounds have aroused widespread interest, for its ultralow lattice thermal conductivity. The first-principles calculations and Boltzmann transport theory are used to study the TE transport properties of n-type doped full-Heusler compounds X 2 YAu (X = Sr, Ba; Y = As, Sb). At room-temperature, the calculated lattice thermal conductivities are 1.02, 0.89, 0.79, and 0.53 W/mK for Sr 2 AsAu, Ba 2 AsAu, Sr 2 SbAu, and Ba 2 SbAu, respectively. The ultralow κ L is mainly by the extremely low υ q and relatively high 1=τ q . By combining the calculated TE transport coefficients, we get the excellent dimensionless TE figure of merit zT of X 2 YAu (X = Sr, Ba; Y = As, Sb). The calculated zT of Sr 2 AsAu, Ba 2 AsAu, Sr 2 SbAu, and Ba 2 SbAu are 0.89, 0.59, 1.55, 0.87 at 300 K and 3.35, 2.15, 4.45, 2.91 at 700 K, which indicate that X 2 YAu (X = Sr, Ba; Y = As, Sb) are potential and excellent TE materials.

Computational Exploration of Ultralow Lattice Thermal Conductivity and High Figure of Merit in p-Type Bulk RbX2Sb (X = K, Na)

“…The motivation for considering RbK 2 Sb and RbNa 2 Sb bialkali antimonides (also known as "full-Heusler (FH) compounds") as a TE material comes from the previously reported works on FH as TE materials with excellent figure of merits. For instance, n-and p-type Ba 2 AuBi shows a ZT as high as 5 and 2 at 800 K with ultralow lattice thermal conductivity 0.2 (0.55) W m −1 K −1 at 800 K (300 K); 18 a predicted ZT for n-type Sr 2 BiAu and n-type Sr 2 SbAu of 4.9 at 700 K and 3.4 at 750 K, respectively; 19 and a ZT for n-type Sr 2 AsAu of 3.3 at 700 K. 20 Most of the FH compounds reported earlier as TE materials show high ZT for their n-type cases. Previous electronic structure 21 calculations report that RbK 2 Sb and RbNa 2 Sb have a high density of states with steepness at the valence band maximum (VBM) level, so they may have a high Seebeck coefficient for p-type cases and would be good p-type TE materials with a low lattice thermal conductivity like other FH compounds.…”

Impressive Electronic and Thermal Transports in CsK2Sb: A Thermoelectric Perspective

“…21 Similarly, another category with a VEC of 10 has been explored exhibiting remarkably low (κ L ) and high PF. 22 For instance, the n-type compound Sr 2 AuSb achieves a ZT of approximately 4.4 at 750 K, 23 while n-type Ba 2 AuBi records a ZT of about 5 at 800 K. 24 Similarly, n-type Sr 2 AuAs showcases a ZT of roughly 3.35 at 700 K. 25 Importantly, these FH compounds rely on the rare noble metal gold (Au), substantially increasing the cost of thermoelectric materials and limiting their global applications due to gold scarcity. Furthermore, often disregarded 8 VEC such as CsK 2 Sb offers distinct benefits.…”

“…For instance, the n-type compound Sr 2 AuSb achieves a ZT of approximately 4.4 at 750 K, while n-type Ba 2 AuBi records a ZT of about 5 at 800 K . Similarly, n-type Sr 2 AuAs showcases a ZT of roughly 3.35 at 700 K . Importantly, these FH compounds rely on the rare noble metal gold (Au), substantially increasing the cost of thermoelectric materials and limiting their global applications due to gold scarcity.…”

Study on the thermoelectric characteristics of the ternary alkali metal compound XMgSb (X = K, Rb, Cs)

“…In addition, achieving high TE performance by reducing the lattice thermal conductivity is also a very important approach, because in theory, we can reduce κ L to reach the limit of amorphous solids [10][11][12][13]. And low κ L usually means strong anharmonicity [14,15], low phonon group velocity v ph [16,17] and strong phonon scattering [18,19].…”