Electronic Orbital Alignment and Hierarchical Phonon Scattering Enabling High Thermoelectric Performance p-Type MgSb Zintl Compounds.

Environmentally friendly MgSb-based materials have drawn intensive attention owing to their promising thermoelectric performance. In this work, the electrical properties of p-type MgSb are dramatically optimized by the regulation of Mg deficiency. Then, we, for the first time, found that Zn substitution at the Mg2 site leads to the alignment of and orbital, resulting in a high band degeneracy and the dramatically enhanced Seebeck coefficient, demonstrated by the DFT calculations and electronic properties measurement.

Nanotwins Strengthening High Thermoelectric Performance Bismuth Antimony Telluride Alloys.

Bi Te based thermoelectric alloys have been commercialized in solid-state refrigeration, but the poor mechanical properties restrict their further application. Nanotwins have been theoretically proven to effectively strengthen these alloys and could be sometimes constructed by strong deformation during synthesis. However, the obscure underlying formation mechanism restricts the feasibility of twin boundary engineering on Bi Te based materials.

Defect Engineering: Electron-Exchange Integral Manipulation to Generate a Large Magnetocaloric Effect in NiMnCoSn Alloys.

A promising magnetocaloric effect has been obtained in Ni-(Co)-Mn-X (X = Sn, In, Sb)-based Heusler alloys, but the low isothermal magnetic entropy change Δ restricts the further promotion of such materials. Defect engineering is a useful method to modulate magnetic performance and shows great potential in improving the magnetocaloric effect. In this work, dense Ni vacancies are introduced in NiMnCoSn alloys by employing high-energy electron irradiation to adjust the magnetic properties.

Enhancing Thermoelectric Performance of YbCoSb by Synergistically Optimized Carrier Concentration and Ionized Impurity Scattering.

Previous results indicated that acceptor doping was considered an effective clue to substantially suppress electronic thermal conductivity and in the meanwhile hold a rather low lattice thermal conductivity in high Yb-filled skutterudites. However, the strength of ionized impurity scattering needs to be regulated elaborately to balance the enhanced Seebeck coefficient and the deteriorated carrier mobility. In this work, Ge doping not only synergistically modulates the Fermi energy level and strength of ionized impurity scattering to an optimal range and attains a benign power factor but also offers a valuable opportunity to further suppress κ and κ in the classic YbCoSb alloy.

Enhanced Thermoelectric and Mechanical Performance in n-Type Yb-Filled Skutterudites through Aluminum Alloying.

Herein, we demonstrate a synergistic combination of novel mechanisms in aluminum (Al)-alloyed YbCoSb-based thermoelectric materials to address both reduction in thermal conductivity and concomitant enhancement in power factor (PF). Upon Al alloying, CoAl nanoprecipitates are embedded in the matrix, leading to (1) significant local strain and thus intensified phonon scattering and (2) carrier injection because of interphase electron transfer. Moreover, by decreasing the Yb filling fraction, not only is the electronic thermal conductivity significantly suppressed but also the carrier concentration is modulated to the optimum range, thus resulting in the dramatically boosted PF, especially below 773 K.

Enhanced Thermoelectric Properties of p-Type CaMgBi via a Synergistic Effect Originated from Zn and Alkali-Metal Co-doping.

Bi-based Zintl phase CaMgBi is a promising thermoelectric material. Here, we report that the high-concentration point defects induced by equivalent Zn doping on the Mg site significantly enhance phonon scattering and then suppress lattice thermal conductivity by 50% at room temperature. Subsequently, partial substitution of divalent calcium ions with alkali-ion doping (Li, Na, K) not only optimizes the electrical transport properties by increasing the carrier concentration but also further reduces the lattice thermal conductivity through crystal disorder.

Achieving a High Average Value in SbTe-Based Segmented Thermoelectric Materials.

A tiny amount of Mn is doped in InSbTe sample to tailor its carrier concentration, thus boosting the power factor and suppressing the bipolar effect. Furthermore, large amounts of nanotwins are constructed to effectively scatter the phonons and reduce the lattice thermal conductivity. As a result, the value of MnInSbTe is enhanced up to 1.