Due to the excellent thermoelectric performance, bismuth telluride (Bi2Te3) compounds are highly promising for the thermoelectric conversion in the room temperature range. However, the inferior thermoelectric performance of the n-type leg severely restricts the applications of Bi2Te3-based thermoelectric couples. Herein, n-type Bi2Te2.7Se0.3 (BTS)-based thermoelectric materials incorporated with nanosized Y2O3 (0.5–3 wt %) are prepared and their thermoelectric properties are systematically studied. The dramatically improved thermoelectric performance is ascribed to the realization of a multiscale feature of Y2O3 nanoparticle (NP)-induced interfacial decorations distributed along grain boundaries, which creates massive BTS/Y2O3 interfaces for the manipulation of carrier and phonon transport properties. The geometric phase analysis is employed to further confirm the condition of local strain in the BTS composite incorporated with Y2O3 NPs. Due to the presence of heterointerfaces and high density of dislocations in BTS matrices, the minimum lattice thermal conductivity (κl) of the nanocomposites (NCs) is dramatically suppressed from 0.76 to 0.37 W m–1 K–1. With the incorporation of 3 wt % Y2O3 NPs, the Vickers hardness of the BTS/Y2O3 NC is increased by about 32%. Overall, the BTS + 1.5 wt % Y2O3 NC maintains excellent thermoelectric properties (ZTave = 1.1) in the whole operative temperature range (300–500 K). The present strategy of implementing high-density heterogeneous interfaces by Y2O3 NP addition offers an applicable pathway for fabricating high-performance thermoelectric materials with both optimized thermoelectric properties and mechanical properties.

Most achievements on remarkable thermoelectric performance have been made in the intermediate-temperature p-type PbTe. However, the n-type PbTe exhibits a relatively poor figure of merit ZT, which is urgently expected to be enhanced and compatible with the p-type counterpart. Here, we report that the introduction of excessive Pb can effectively eliminate cation vacancies in the n-type Pb1+xTe−0.4%I, leading to a considerable improvement of carrier mobility μ. Moreover, further Ge doping induces a large enhancement of thermoelectric properties due to the combined effect of improved electrical transport properties and increased phonon scattering in the n-type Pb1.01Te−0.4%I−y%Ge. The Ge doping not only contributes to the increase of the Seebeck coefficient owing to the increased effective mass m∗, but also gives rise to the dramatic decrease of lattice thermal conductivity due to the strengthened point defects scattering. As a result, a tremendous enhancement of the ZT value at 723 K reaches ∼1.31 of Pb1.01Te−0.4%I−3%Ge. Particularly, the average ZTave value of ∼0.87 and calculated conversion efficiency η∼13.5% is achieved by Ge doping in a wide temperature range from 323 to 823 K. The present findings demonstrate the great potential in the n-type Pb1.01Te−0.4%I−y%Ge through a synergistic tuning of carrier mobility, effective mass, and point defects engineering strategy.

No abstract

No abstract

Tungsten-potassium (potassium-doped tungsten or WK), initially known from the electric filament industry, is a promising plasma-facing material (PFM) in future fusion facilities like International Thermonuclear Experimental Reactor (ITER). However, the brittle nature of W and irradiation-induced defects of WK materials may result in a risk of deuterium-tritium reaction failure in fusion reactors. Previous studies revealed that advanced W with ultrafine grains and nanostructures might be able to address these problems. However, K-doped W, a rapidly developed material for PFMs, lacks a systematical summary. In this review, we firstly describe the powder metallurgy and plastic deformation for the preparation of WK. Then, the mechanical properties of WK and thermal shock resistance results are reviewed. Important issues such as irradiation damages from neutron, heavy ion, and plasma (H isotope or He) irradiation are also discussed. Hitherto, WK under irradiations shows comparable or even better performances compared with other counterparts such as ITER grade pure tungsten. This review could be benefitial to the future efforts of improving the ductility and irradiation tolerance of WK materials.