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In this paper, p-type thermoelectric material Te–Se solid solutions have been successfully prepared by the high-pressure technique. The thermal conductivity of Te was depressed sharply by Se alloying. An extremely low thermal conductivity ∼0.27 W m−1 K−1 was obtained for Te alloyed with 15 mol% Se, which near the theoretical minimum, κ min. The bipolar diffusion effect of Te was suppressed by Se alloying due to the increased band gap, which lead to enhanced Seebeck coefficient and depressed bipolar diffusion thermal conductivity under high temperature. The maximum figure of merit, ZT of 0.37 at 480 K was obtained for Te alloyed with 5 mol% Se, which is about twice higher than that of pristine Te. • Thermoelectric Te–Se solid solutions were facile and fast prepared by one-step high-pressure technique. • The thermal conductivity of Te was depressed sharply and its Seebeck was improved at high temperatures by Se alloying. • An extremely low thermal conductivity ∼0.27 W m−1 K−1 was obtained for Te alloyed with 15 mol%. [ABSTRACT FROM AUTHOR]

Recently, it was found that element semiconductor tellurium (Te) has a high thermoelectric performance. However, it needs to be doped with high-toxic arsenic (As) to tune the carrier concentration of Te. In this paper, low-toxic bismuth (Bi) was employed as dopant to optimize the thermoelectric performance of Te combining with a high-pressure synthesis method. The effect of substituting Bi on the electrical transport and thermal transport properties of Te has been investigated. The results show that the solubility limit of Bi in Te is about 0.1 mol%. However, the trace amounts of Bi doping can tune the carrier concentration of Te effectively and thereby optimize its power factor. The thermal conductivity of non-doped Te prepared by high pressure is much lower than that of the sample prepared at ambient pressure. And Bi doping can further decrease the value due to the phonons scattered by the heavy impurity atom. An enhanced figure of merit ZT ~ 0.72 was obtained at 517 K, which is about four times that of non-doped Te and is comparable to the state-of-the-art thermoelectric alloys with more complex composition such as BiTe and PbTe. [ABSTRACT FROM AUTHOR]

N-type thermoelectric materials PbTe doped with iodine (PbTe 1−x I x , x = 0.0001, 0.0003, 0.0007 and 0.001) were synthesized by high pressure and high temperature method (HPHT). Thermoelectric properties of PbTe 1−x I x are investigated in the range of 300–600 K. The carrier concentration of PbTe prepared by HPHT is more sensitive to I content compared to that of the PbTe 1−x I x sample prepared by other methods. The resistivities and the absolute values of Seebeck coefficients for PbTe 1−x I x increase while the thermal conductivities decrease with increasing temperature. A large power factor of 39.1 μW/(cmK 2 ) at room temperature is obtained with the carrier concentration of 9.7 × 10 18 cm −3 , which is much higher than that of Sb and Bi doped PbTe with the same synthesizing conditions. The high power factor is attributed to the high Hall mobility and large effective mass. The maximum figure-of-merit, ∼0.71 @ 600 K, is obtained for the samples with the carrier concentration of 9.7 × 10 18 cm −3 . [ABSTRACT FROM AUTHOR]

Paracostibite (CoSbS) consists of earth-abundant and low-cost elements, which has received a lot of attention as a newly developed thermoelectric material. In this report, Se-alloyed CoSbS samples with the composition of CoSb 1−x Se x S (x ≤ 0.2) have been synthesized by the melting annealing process combined with the spark plasma sintering method. It was found that Se alloying can tune the band gap and impurity conductance activation energy of CoSbS effectively, which leads to an increased carrier concentration and an enhanced power factor. The thermal conductivity was sharply suppressed because Se alloying induced the mass fluctuation and strain field fluctuation. The maximum zT of 0.22 was achieved for CoSb 0.9 Se 0.1 S at 823 K, which is about twice that of the pristine CoSbS. In particular, the solid solution CoSb 1−x Se x S has a higher average zT than that of CoSbS 1−x Se x prepared by the same method. The research shows that the construction of antisite defect of Se Sb in CoSbS is an effective route to optimize its thermoelectric performance. [Display omitted] • CoSbS thermoelectric compound contained anti-site defect of Se Sb were synthesized. • The band gap and impurity activation energy of CoSbS decrease after Se alloying. • CoSb 1−x Se x S solid solution has higher average zT than that of CoSbS 1−x Se x. [ABSTRACT FROM AUTHOR]

Designing new compounds with earth-abundant constituent elements and intrinsically low thermal conductivity are crucial to the development of thermoelectric materials. In this letter, the tetragonal-structured PbSe 2 with extremely low thermal conductivity was prepared by two-step ball milling and high pressure synthesis method. Density functional theory calculation shows that the low thermal conductivity of PbSe 2 is originated from its weak interatomic bonding strength and high lattice vibration anharmonicity. We also found that the carrier concentration of PbSe 2 can be tuned effectively by Ag doping in Pb site, which leads to an enhanced figure of merit. These results indicate that PbSe 2 is a potential candidate as a thermoelectric material. • Tetragonal structured PbSe 2 was synthesized by a high-pressure method. • PbSe 2 behaves an extremal low thermal conductivity. • The carrier concentration and ZT of PbSe 2 was enhanced effectively by Ag doping. [ABSTRACT FROM AUTHOR]

Abstract: Non-stoichiometric Ag1−x Pb18SbTe20 (x =0, 0.2, 0.5, 0.7, 0.85) thermoelectric materials were prepared by high pressure method. The composition-dependent transport properties were studied at room temperature. The measurement results show that the carrier concentration and hall mobility of AgPb18SbTe20 could be tuned effectively by adjusting the content of Ag. The Seebeck coefficient and resistivity decrease with an increase of x. The maximum power factor of 2.3×10−3 Wm−1 K−2 is obtained at x =0.7, which is about 76% higher than that of the sample with stoichiometric composition. [ABSTRACT FROM AUTHOR]

• Thermoelectric oxide BiCuSeO was facile prepared by one-step high-pressure method. • The sample contains fine grains and a large number of multiscale nanoparticles. • An extremely low thermal conductivity and enhanced ZT of BiCuSeO was obtained. BiCuSeO based materials have been drawn much attention since they were found to be excellent thermoelectric materials recently. Apart from high performance, the time and energy-efficient synthesis of BiCuSeO is also essential for its commercialization. In this paper, a simple one-step high pressure method was used to quickly synthesize the copper-deficient BiCuSeO. The introduction of Cu vacancy improves the carrier concentration and power factor. Through the phonon scattering of fine grains and crystal defects caused by Cu deficiency and high pressure compression, an extremely low phonon thermal conductivity of BiCu 0.94 SeO ~ 0.3 Wm−1K−1 @ 750 K is obtained. An enhanced ZT ~ 0.87 at 750 K is obtained for BiCu 0.94 SeO. This value is twice higher than that of the original BiCuSeO, compared with the traditional time-consuming method. [ABSTRACT FROM AUTHOR]

Besides inferior conversion efficiency, the widespread application of thermoelectric materials currently faces the challenges of the rare and high cost of constituent elements, complex and time-consuming synthesis. Therefore, it is urgent to develop facile synthesized methods and high-performance thermoelectric materials consisting of elements with earth-abundance and low cost. Meeting above partial requirement, lead sulfide (PbS) recently was identified as a potential thermoelectric material to substitute current commercial PbTe. In this paper, a one-step high-pressure method was employed to facile and fast synthesis of PbS. Trace Cl doping tunes the carrier concentration of PbS effectively, which optimizes the electrical transport properties. Further PbSe alloying sharply reduces the thermal conductivity of PbS. Therefore, an enhanced zT ∼1.0 @ 700 K was obtained for PbS doped with 0.3 at% Cl and alloyed with 25 at% PbSe, which is comparable to the commercially applied PbTe. These results indicate that high-pressure combing with Cl-doping and PbSe-alloying provide a facile method and strategy to fabricate high-performance PbS-based thermoelectric materials. • Earth-abundant and low-cost thermoelectric compound PbS was facile and fast synthesized by one-step high pressure method. • Cl doping modulates the carrier concentration of PbS and thus optimizes its electrical properties at high temperature. • The chemical bond of PbS was weaken by PbSe alloying, which induces an enhanced Hall mobility near room temperature. • The thermal conductivity of PbS was suppressed sharply by PbSe alloying. • The enhanced zT max and zT avg achieve to 1.0 and 0.67 for PbS 0.747 Cl 0.003 Se 0.25 and PbS 0.497 Cl 0.003 Se 0.5, respectively [ABSTRACT FROM AUTHOR]