分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: A fundamental understanding of phonon transport in stanene is crucial to predict the thermal performance in potential stanene-based devices. By combining rst-principle calculation and phonon Boltzmann transport equation, we obtain the lattice thermal conductivity of stanene. A much lower thermal conductivity (11.6W/mK) is observed in stanene, which indicates higher thermoelectric e ciency over other 2D materials. The contributions of acoustic and optical phonons to the lattice thermal conductivity are evaluated. Detailed analysis of phase space for three-phonon processes shows that phonon scattering channels LA + LA/TA/ZA ↔ TA/ZA are restricted, leading to the dominant contributions of high-group-velocity LA phonons to the thermal conductivity. The size dependence of thermal conductivity is investigated as well for the purpose of the design of thermoelectric nanostructures.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: SnCdxTe materials were synthesized by the zone-melting method for this thermoelectric performance study. The X-ray diffraction results show that the lattice parameter decreases with increasing x, following Vegard's law of rock-salt structure SnTe and CdTe. Besides, the room temperature Seebeck coefficients of the SnCdxTe system are enhanced to >60 mV K 1, larger than those of Cd-doped SnTe synthesized by spark plasma sintering. A large power factor of $25 mW cm 1 K 1 is achieved in SnCd0.12Te at 820 K, which rivals those of high performance PbTe-based materials. As a result, the highest ZT of $1.03 at 820 K was achieved for SnCd0.12Te.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-05-02
摘要: Tin selenide (SnSe) compound has attracted much attention due to its unprecedented high ZT (B2.6) in single crystals. The polycrystalline SnSe materials were then prepared to improve the mechanical performance for large-scaled application. However, the ZT values of 0.3–0.8 were much lower due to their poor electrical properties. In the present study, the zone melting method is employed to prepare the polycrystalline SnSe samples, which show highly textured structures and strong anisotropic thermoelectric performance. A maximum power factor (S2s) of 9.8 mW cm 1 K 2 was obtained in the polycrystalline samples, which is comparable with that of SnSe single crystals, resulting in a peak ZT of 0.92 at 873 K. The zone-melted ingot was then pulverized into powders and the bulk material was prepared by the spark plasma sintering (SPS) technique. As a result, the ZT value was enhanced to be over 1.0, owing to the slight reduction of lattice thermal conductivity and maintenance of electrical performance. The present investigation indicates that the TE performance of the SnSe compound can be significantly improved by the texture modulation.