SnTe 基热电材料的制备及性能优化机制研究

       热电转换技术作为最简单直接的热能与电能相互转换的技术，是应对能源危机与环境污染的重要途径。开发高性能、无污染的热电材料，是决定热电技术能否 实现更多应用的关键。Ⅳ-Ⅵ族化合物是研究且投入使用最早的热电材料之一。在 中温区（550-950 K）热电材料中，SnTe 具有与 PbTe 相同的晶体结构和相似的能带 结构，且 Sn 无毒无污染。因此研究如何调控 SnTe 的载流子输运能力，使其能取 代 PbTe 实现高热电性能并环境友好的材料，具有重要意义。但本征 SnTe 半导体 材料过高的载流子浓度、较大的轻重价带能量差和较高的晶格热导率，极大地抑 制了本征 SnTe 的热电性能，使得其热电性能相较 PbTe 仍有很大的提升空间，如 何提高 SnTe 热电性能的问题亟待解决。

       本课题通过高温熔炼-淬火-中高温长时间退火结合放电等离子烧结的工艺制 备了 p 型 SnTe 基热电材料，对其进行电热输运分析，主要的研究成果如下：

（1）Sb 元素可以增大 SnTe 合金的带隙，使得双极扩散效应减弱，实现电、热 的协同优化；而 Sn1−3𝑥/2Sb𝑥Te 材料由于其晶格内部大量的空位增强了对于声子 的散射，使得该体系拥有更加优异的热导率，最终使得 Sn0.82Sb0.12Te 材料的热电 优值在 823K 时达到 1.1，较纯 SnTe 合金提升 55 %;

（2）Pb 元素的引入可以实现载流子浓度数量级的下降，进一步优化 Seebeck 系数。另外，其与 Sn 之间较大的原子质量差和尺寸差，引入了质量和应力场波动， 加强了点缺陷带来的散射，显著降低了晶格热导率。使得Sn0.70S b0.10P b0.15T e在 323-823 K区间内其平均ZT 值为0.7，较纯SnTe合金提升278%;

（3）Mn 掺杂会使得 SnTe 基材料发生能带汇聚，使得重带参与运输，增大能 谷简并度，提高整个温度区间内的 Seebeck 系数。同时也使得其热导率进一步降 低：一方面晶格内部的位错以及空位缺陷加强了对声子的散射，另一方面随着掺杂 元素种类的增加，体系熵增导致原子在晶体内部的分布变得高度无序，引入强烈 的晶格扭曲使得晶格热导率一降再降。最终使 Sn0.61S b0.10P b0.15Mn0.09T e 在 823K 时获得了 1.4 的热电优值，而 Sn0.57S b0.10P b0.15Mn0.13T e 合金在 298-823 K 间的平 均 𝑍𝑇 值达到 0.8，较纯 SnTe 材料提升了 355 %。

[1] GOLDSMID H J. Introduction to Thermoelectricity[M]. 2016.
[2] SEEBECK T J. Ueber die magnetische Polarisation der Metalle und Erze durch Temperaturdifferenz[J]. Annalen der Physik, 1826, 82(3): 253-286.
[3] MAGNUS G. Ueber thermoelektrische Ströme[J]. Annalen der Physik, 1851, 159(8): 469-504.
[4] SUNDERLAND J E, BURAK N T. The influence of the Thomson effect on the performance of a thermoelectric power generator[J]. Solid-State Electronics, 1964, 7(6): 465-471.
[5] VINING C. Semiconductors are cool[J]. Nature, 2001, 413(6856): 577-578.
[6] ONSAGER L. Reciprocal Relations in Irreversible Processes. I.[J]. Physical review, 1931, 37(4): 405-426.
[7] IOFFE A F, STIL’BANS L, IORDANISHVILI E, et al. Semiconductor Thermoelements and Thermoelectric Cooling[J]. Physics Today, 1959, 12(5): 42.
[8] HE J, TRITT T M. Advances in thermoelectric materials research: Looking back and moving forward[J]. Science, 2017, 357(6358): eaak9997.
[9] JAZIRI N,BOUGHAMOURA A, MüLLER J, et al. A comprehensive review of Thermoelectric Generators: Technologies and common applications[J]. Energy Reports, 2020, 6: 264-287.
[10] BERETTA D, MASSETTI M, LANZANI G, et al. Thermoelectric characterization of flexible micro-thermoelectric generators[J]. Review of Scientific Instruments, 2017, 88(1): 015103.
[11] BERETTA D, NEOPHYTOU N, HODGES J M, et al. Thermoelectrics: From history, a window to the future[J]. Materials Science and Engineering: R: Reports, 2019, 138: 100501.
[12] TANG J, GAO B, LIN S, et al. Manipulation of Band Structure and Interstitial Defects for Improving Thermoelectric SnTe[J]. Advanced Functional Materials, 2018, 28(34): 1803586.
[13] HE J, TAN X, XU J, et al. Valence band engineering and thermoelectric performance optimization in SnTe by Mn-alloying via a zone-melting method[J]. Journal of Materials Chemistry A,2015, 3(39): 19974-19979.
[14] LI S, LI X, REN Z, et al. Recent progress towards high performance of tin chalcogenide thermoelectric materials[J]. Journal of Materials Chemistry A, 2018, 6(6): 2432-2448.
[15] SHI X L, ZOU J, CHEN Z G. Advanced Thermoelectric Design: From Materials and Structures to Devices[J]. Chemical Reviews, 2020, 120(15): 7399-7515.
[16] LIU W, HU J, ZHANG S, et al. New trends, strategies and opportunities in thermoelectric materials: A perspective[J]. Materials Today Physics, 2017, 1: 50-60.
[17] HUANG B L, KAVIANY M. Ab initio and molecular dynamics predictions for electron and phonon transport in bismuth telluride[J]. Physical Review B, 2008, 77(12): 125209.
[18] LI J, SUI J, BARRETEAU C, et al. Thermoelectric properties of Mg doped p-type BiCuSeO oxyselenides[J]. Journal of Alloys and Compounds, 2013, 551: 649-653.
[19] NOLAS G S, SHARP J, GOLDSMID H J. Thermoelectrics: Basic Principles and New Materials Developments[C]//2001.
[20] DIMMOCK J O, MELNGAILIS I, STRAUSS A J. Band Structure and Laser Action in Pb𝑥Sn1−𝑥Te[J]. Physical Review Letters, 1966, 16: 1193-1196.
[21] MADELUNG O. Non-tetrahedrally bonded elements and binary compounds I[C]//1998.
[22] MA Z, LEI J, ZHANG D, et al. Enhancement of Thermoelectric Properties in Pd-In Co-Doped SnTe and Its Phase Transition Behavior[J]. ACS Applied Materials & Interfaces, 2019, 11(37): 33792-33802.
[23] AL RAHAL AL ORABI R, MECHOLSKY N A, HWANG J, et al. Band Degeneracy, Low Thermal Conductivity, and High Thermoelectric Figure of Merit in SnTe–CaTe Alloys[J]. Chemistry of Materials, 2016, 28(1): 376-384.
[24] BREBRICK R. Deviations from stoichiometry and electrical properties in SnTe[J]. Journal of Physics and Chemistry of Solids, 1963, 24(1): 27-36.
[25] WANG N, WEST D, LIU J, et al. Microscopic origin of the p-type conductivity of the topological crystalline insulator SnTe and the effect of Pb alloying[J]. Physical Review B, 2014, 89(4): 045142.
[26] TAN G, ZHAO L D, SHI F, et al. High thermoelectric performance of p-type SnTe via a synergistic band engineering and nanostructuring approach[J]. Journal of the American Chemical Society, 2014, 136(19): 7006-7017.
[27] BANIK A, SHENOY U S, ANAND S, et al. Mg Alloying in SnTe Facilitates Valence Band Convergence and Optimizes Thermoelectric Properties[J]. Chemistry of Materials, 2015, 27(2): 581-587.
[28] ROYCHOWDHURY S, BISWAS K. Effect of In and Cd co-doping on the thermoelectric properties of Sn1−𝑥Pb𝑥Te[J]. Materials Research Express, 2019, 6(10): 104010.
[29] LI B, SUN Q, ZHANG Y, et al. Functionalized Porous Aromatic Framework for Efficient Uranium Adsorption from Aqueous Solutions[J]. ACS Applied Materials & Interfaces, 2017, 9(14): 12511-12517.
[30] BANIK A, BISWAS K. AgI alloying in SnTe boosts the thermoelectric performance via simultaneous valence band convergence and carrier concentration optimization[J]. Journal of Solid State Chemistry, 2016, 242: 43-49.
[31] PENG P P, WANG C, LI L W, et al. Research status and performance optimization of mediumtemperature thermoelectric material SnTe[J]. Chinese Physics B, 2022, 31(4): 047307.
[32] ZHANG Q, GUO Z, TAN X, et al. Effects of AgBiSe2 on thermoelectric properties of SnTe[J]. Chemical Engineering Journal, 2020, 390: 124585.
[33] MA Z, WANG C, CHEN Y, et al. Ultra-high thermoelectric performance in SnTe by the integration of several optimization strategies[J]. Materials Today Physics, 2021, 17: 100350.
[34] KORRINGA J, GERRITSEN A. The cooperative electron phenomenon in dilute alloys[J]. Physica, 1953, 19(1): 457-507.
[35] HEREMANS J, JOVOVIC V, TOBERER E, et al. Enhancement of thermoelectric efficiency in PbTe by distortion of the electronic density of states[J]. Science, 2008, 321(5888): 554-557.
[36] KULBACHINSKII V A, BRANDT N B, CHEREMNYKH P A, et al. Magnetoresistance and Hall Effect in Bi2Te3 in Ultrahigh Magnetic Fields and under Pressure[J]. Physica Status Solidi B-basic Solid State Physics, 1988, 150: 237-243.
[37] ZHANG Q, WANG H, LIU W, et al. Enhancement of thermoelectric figure-of-merit by resonant states of aluminium doping in lead selenide[J]. Energy & Environmental Science, 2012, 5: 5246-5251.
[38] ZHANG Q, LIAO B, LAN Y, et al. High thermoelectric performance by resonant dopant indium in nanostructured SnTe[J]. Proceedings of the National Academy of Sciences of the United States of America, 2013, 110(33): 13261-13266.
[39] YANG Q, LYU T, LI Z, et al. Realizing widespread resonance effectsto enhance thermoelectric performance of SnTe[J]. Journal of Alloys and Compounds, 2021, 852: 156989.
[40] TAN X J, SHAO H Z, HE J, et al. Band engineering and improved thermoelectric performance in M-doped SnTe (M = Mg, Mn, Cd, and Hg)[J]. Physical Chemistry Chemical Physics, 2016, 18: 7141-7147.
[41] XU W, ZHANG Z, LIU C, et al. Substantial thermoelectric enhancement achieved by manipulating the band structure and dislocations in Ag and La co-doped SnTe[J]. Journal of Advanced Ceramics, 2021, 10: 1-11.
[42] ZHAO L, WANG J, LI J, et al. High thermoelectric performance of Ag doped SnTepolycrystalline bulks via the synergistic manipulation of electrical and thermal transport[J]. Physical Chemistry Chemical Physics, 2019, 21(32): 17978-17984.
[43] MOSHWAN R, LIU W D, SHI X L, et al. Realizing high thermoelectric properties of SnTe via synergistic band engineering and structure engineering[J]. Nano Energy, 2019, 65: 104056.
[44] YANG J, XI L, QIU W, et al. On the tuning of electrical and thermal transport in thermoelectrics: An integrated theory-experiment perspective[J]. NPJ Computational Materials, 2016, 2: 15015.
[45] TAN G, HAO S, HANUS R C, et al. High Thermoelectric Performance in SnTe–AgSbTe2 Alloys from Lattice Softening, Giant Phonon–Vacancy Scattering, and Valence Band Convergence [J]. ACS Energy Letters, 2018, 3(3): 705-712.
[46] GANGJIAN T, ZEIER W, SHI F, et al. High Thermoelectric Performance SnTe–In2Te3 Solid Solutions Enabled by Resonant Levels and Strong Vacancy Phonon Scattering[J]. Chemistry of Materials, 2015, 27(22): 7801-7811.
[47] SLADE T J, PAL K, GROVOGUI J A, et al. Contrasting SnTe–NaSbTe2 and SnTe–NaBiTe2 Thermoelectric Alloys: High Performance Facilitated by Increased Cation Vacancies and Lattice Softening[J]. Journal of the American Chemical Society, 2020, 142(28): 12524-12535.
[48] TAN G, SHI F, SUN H, et al. SnTe–AgBiTe2 as an efficient thermoelectric material with low thermal conductivity[J]. Journal of Materials Chemistry A, 2014, 2: 20849-20854.
[49] ZHANG Y, SUN J, SHUAI J, et al. Lead-free SnTe-based compounds as advanced thermo-electrics[J]. Materials Today Physics, 2021, 19: 100405.
[50] ZHAO L D, ZHANG X, WU H, et al. Enhanced Thermoelectric Properties in the Counter-Doped SnTe System with Strained Endotaxial SrTe[J]. Journal of the American Chemical Society, 2016, 138(7): 2366-2373.
[51] BANIK A, VISHAL B, PERUMAL S, et al. The origin of low thermal conductivity in Sn1-xSbxTe: phonon scattering via layered intergrowth nanostructures[J]. Energy &Environmental Science, 2016, 9(6): 2011-2019.
[52] TAN G J, SHI F Y, HAO S Q, et al. Valence Band Modification and High Thermoelectric Performance in SnTe Heavily Alloyed with MnTe[J]. Journal of the American Chemical Society, 2015, 137 (35): 11501-11516.
[53] GUO F, CUI B, LIU Y, et al. Thermoelectric SnTe with Band Convergence, DenseDislocations, and Interstitials through Sn Self-Compensation and Mn Alloying[J]. Small, 2018, 14(37): 1802615.
[54] WU D, CHEN X, ZHENG F, et al. Dislocation Evolution and Migration at Grain Boundaries in Thermoelectric SnTe[J]. ACS Applied Energy Materials, 2019, 2(4): 2392-2397.
[55] HANUS R, AGNE M T, RETTIE A J E, et al. Lattice Softening Significantly Reduces Thermal Conductivity and Leads to High Thermoelectric Efficiency[J]. Advanced Materials, 2019, 31(21): 1900108.
[56] BACK S Y, CHO H, KIM Y K, et al. Enhancement of thermoelectric properties by lattice softening and energy band gap control in Te-deficient InTe1−δ[J]. AIP Advances, 2018, 8(11): 115227.
[57] ZHOU C, YU Y, LEE Y K, et al. High-Performance n-Type PbSe–Cu2Se Thermoelectrics through Conduction Band Engineering and Phonon Softening[J]. Journal of the American Chemical Society, 2018, 140(45): 15535-15545.
[58] CAI S. Design of High-Performance Thermoelectric Materials through All-Scale Architecture Construction and Band Structure Tailoring[D]. Northwestern University, 2021.
[59] P. POUDEU P, D’ANGELO J, KONG H, et al. Nanostructures versus Solid Solutions: Low Lattice Thermal Conductivity and Enhanced Thermoelectric Figure of Merit in Pb9.6Sb0.2Te10-xSex Bulk Materials[J]. Journal of the American Chemical Society, 2006, 128(44): 14347-55.
[60] SOOTSMAN J, KONG H, UHER C, et al. Large Enhancements in the Thermoelectric Power Factor of Bulk PbTe at High Temperature by Synergistic Nanostructuring[J]. Angewandte Chemie International Edition, 2008, 47(45): 8618-8622.
[61] MIN Y, KIM M, HWANG G T, et al. Vacancy engineering in rock-salt type (IV-VI)x(V-VI) materials for high thermoelectric performance[J]. Nano Energy, 2020, 78: 105198.
[62] XIA J, HUANG Y, XU X, et al. Fine electron and phonon transports manipulation by Mn compensation for high thermoelectric performance of Sb2Te3(SnTe)n materials[J]. Materials Today Physics, 2023, 33: 101055.
[63] XU X, CUI J, YU Y, et al. Constructing van der Waals gaps in cubic-structured SnTe-based thermoelectric materials[J]. Energy & Environmental Science, 2020, 13(12): 5135-5142.
[64] PEI Y, WANG H, GIBBS Z, et al. Thermopower enhancement in Pb1−xMnxTe alloys and its effect on thermoelectric efficiency[J]. NPG Asia Materials, 2012, 4(9): e28.
[65] ROYCHOWDHURY S, SHENOY U S, WAGHMARE U V, et al. An enhanced Seebeckcoefficient and high thermoelectric performance in p-type In and Mg co-doped Sn1−𝑥Pb𝑥Te via the co-adjuvant effect of the resonance level and heavy hole valence band[J]. Journal of Materials Chemistry C, 2017, 5: 5737-5748.
[66] LIJ, CHEN Z, ZHANG X, et al. Simultaneous Optimization of Carrier Concentration and Alloy Scattering for Ultrahigh Performance GeTe Thermoelectrics[J]. Advanced Science, 2017, 4(12): 1700341.
[67] EFIMOVA B, KOLOMOETS L. Thermoelectric properties of PbTe-SnTe solidsolutions(Lead telluride and tin telluride thermal electromotive force and hole mobility measurements)[J]. SOVIET PHYSICS-SOLID STATE, 1965, 7: 339-344.
[68] LI J, CHEN Z, ZHANG X, et al. Simultaneous Optimization of Carrier Concentration and Alloy Scattering for Ultrahigh Performance GeTe Thermoelectrics[J]. Advanced Science, 2017, 4(12): 1700341.
[69] YAO Z, LI W, TANG J, et al. Solute manipulation enabled band and defect engineering for thermoelectric enhancements of SnTe[J]. InfoMat, 2019, 1(4): 571-581.
[70] CAHILL D G, WATSON S K, POHL R O. Lower limit to the thermal conductivity of disordered crystals[J]. Physical Review B, 1992, 46(10): 6131-6140.
[71] 吕途. SnTe 和 Bi2Te3 基热电材料的性能优化研究[D]. 北京科技大学, 2021.