Leveraging crystal symmetry for thermoelectric performance optimization in cubic GeSe

作     者：Yu-Geng Li Yong-Qiang Liu Mo-Ran Wang Wen-Qing Yao Xiao-Huan Luo Tu Lyu Wei-Qin Ao Chao-Hua Zhang Fu-Sheng Liu Li-Peng Hu Yu-Geng Li;Yong-Qiang Liu;Mo-Ran Wang;Wen-Qing Yao;Xiao-Huan Luo;Tu Lyu;Wei-Qin Ao;Chao-Hua Zhang;Fu-Sheng Liu;Li-Peng Hu

作者机构：College of Materials Science and EngineeringInstitute of Deep Earth Sciences and Green EnergyShenzhen Key Laboratory of Special Functional MaterialsGuangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and UtilizationGuangdong Research Center for Interfacial Engineering of Functional MaterialsShenzhen UniversityShenzhen 518060China 

出 版 物：《Rare Metals》 (稀有金属（英文版）)

年 卷 期：2024年第43卷第10期

页      面：5332-5345页

核心收录：

学科分类：08[工学] 080501[工学-材料物理与化学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

基　　金：financially supported by the National Key R&D Program of China(No.2021YFB1507403) the National Natural Science Foundation of China(No.52071218) Shenzhen Science and Technology Innovation Commission(No.JCYJ20230808105700001) Shenzhen University 2035 Program for Excellent Research(No.00000218) 

主　　题：Thermoelectric GeSe Crystal symmetry High-entropy alloying Band degeneracy 

摘      要：In thermoelectrics,the manipulation of crystal symmetry is instrumental in optimizing the electrical and thermal transport *** this context,the present study explored the largely overlooked high-symmetry cubic GeSe,which presented larger band degeneracy than its widely studied medium-symmetry rhombohedral *** have successfully stabilized cubic Ge Se a ambient conditions through co-alloying with AgSnTe_(2)and *** incorporation of AgSnTe_(2)initiates the transition of GeSe from a low-symmetry orthorhombic to a mediumsymmetry rhombohedral phase,culminating in a highsymmetry cubic structure,underpinned by variation in chemical bonding *** this,the persistence of Ag_(2)Te precipitates impedes the total elimination of the residual orthorhombic phase due to the disparate chemical bonding mechanism between Ag_(2)Te and *** Bi into the rhombohedral-dominated(GeSe)_(0.7)(AgSnTe_(2))_(0.3)matrix leads to the dissolution of Ag_(2)Te precipitates,elimination of the residual orthorhombic phase,and the subsequent stabilization of the exclusive cubic *** to its orthorhombic counterpart,the cubic GeSe exhibits diminished bandgap and Ge vacancy formation energy,amplified band degeneracy,reduced sound velocity,intensified lattice anharmonicity and multiple phonon scattering centres engendering elevated carrier concentration and density-ofstates effective mass,alongside restrained lattice therma ***,a peak zT of 0.46 at 573 K is attained for cubic(Ge_(0.7)Bi_(0.3)Se)_(0.7)(AgSnTe_(2))_(0.3),signifying a ninefold increase relative to the initial orthorhombic Ge *** results illuminate the critical role of crystal symmetry manipulation in advancing the thermoelectric performance.