Improving thermal stability and revealing physical mechanism in n-type Mg3Sb2-Bi for practical applications

Band Engineering and Phonon Engineering Effectively Improve n-Type Mg3Sb2 Thermoelectric Material Properties

“…(a, b) n-type Mg 3.2– x Tb x Sb 1.5 Bi 0.5 ( x = 0.005, 0.01, and 0.015) and Mg 3.19– y Tb 0.01 Er y Sb 1.5 Bi 0.5 ( y = 0.005, 0.01, and 0.015) samples in The relationship between carrier concentration, carrier mobility and Er and Tb doping content at 300 K, (c) n-type Mg 3.2– x TbxSb 1.5 Bi 0.5 ( x = 0.005, 0.01 and 0.015) and Mg 3.19– y Tb 0.01 Er y Sb 1.5 Bi 0.5 ( y = 0.005, 0.01 and 0.015) samples of maximum ZT value and average ZT value, and (d) n-type Mg 3.19 Tb 0.01 Sb 1.5 Bi 0.5 and Mg 3.185 Tb 0.01 Er 0.005 Sb 1.5 Bi 0.5 samples with comparison chart of maximum ZT values of other n-type Mg 3 Sb 2 -based thermoelectric materials. ,,,,,,− …”

“…Mg 3 Sb 2 -based thermoelectric materials have the merits of low toxicity and low cost in the medium temperature range. They have been research hotspots in thermoelectricity in recent years. − Shang et al doped cations Co and Er in Mg 3 Sb 2‑x Bi x , calculated by density functional theory that the combination between Co/Er and Sb/Bi is stronger than the bond between Mg and Sb/Bi at 673 K under 100 h of thermoelectric performance measurement, the conductivity and Seebeck coefficient of Mg 3 Sb 2 - x Bi x hardly decreased. , Li et al significantly improved the interlayer migration kinetics of magnesium (Mg) by selectively occupying nickel (Ni) at the interstitial positions of the Mg 3 Sb 2 -based thermoelectric materials. This enhancement resulted in attaining highly stable and long-lasting n-type conduction, with a remarkably high room temperature ZT value of 0.8 .…”

Revealing the Chemical Instability of Mg3Sb2–xBix-Based Thermoelectric Materials

“…It should be noted that the conduction type in Mg 3 Sb 2−x Bi x alloys is closely related to the stoichiometry of Mg. 5,10,30,48 Previous results show that Mg loss occurs at elevated temperatures and can convert the Mg 3 Sb 2 -based material from n-type to p-type. 17,[45][46][47]49 Intuitively, we suspect that a similar Mg loss occurs when Mg 3.1 Sb 0.49 Bi 1.5 Te 0.01 is placed in air for 30 days. Scanning electron microscopy (SEM) analysis prior to and after the reaction in the air is conducted, and the results are shown in Figure S1 (Supporting Information).…”

“…Intuitively, identifying the approach to minimize the Mg loss is meaningful for tuning the thermal stability of Mg 3 Sb 2 -based materials. Experimentally, by coating with boron nitride or MgMn-based alloy, as well as chemical doping, the Mg loss can be effectively suppressed, and the thermal stability of Mg 3 Sb 2– x Bi x can be improved. − …”

Realizing High Thermoelectric Performance in N‐Type Mg3(Sb, Bi)2‐Based Materials via Synergetic Mo Addition and Sb–Bi Ratio Refining

“…This method has been confirmed to improve stability with La, Co, and Er doping in Mg 3 Sb 2 -based alloys. [74,75] In addition, Mg-vapor annealing creates an Mg-rich environment in the grains and GB, leading to an energy barrier that suppresses the Mg loss from the grain. [76] Worthy to note that the above methods are strongly dependent on the Mg vacancy concentration, and the increased vacancy concentration with long-term service can facilitate Mg loss.…”