Abstract
Layered compounds have garnered widespread interest owing to their nontrivial physical properties, particularly their potential as thermoelectric materials. We systematically investigated PbBi2Te4, a compound derived from Bi2Te3 and PbTe. Synchrotron X-ray diffraction and transmission electron microscopy revealed that PbBi2Te4 adopts and maintains the R3̅m phase from 300 to 723 K, without any phase transition. Moreover, neutron pair distribution function analysis confirmed that the short-range local structure was consistent with the high-symmetry R3̅m structure. PbBi2Te4 exhibits a negative Seebeck coefficient, indicating electron-dominated transport. It has a low lattice thermal conductivity (ca. 0.6 Wm-1K-1) and a ZT value of 0.4 at 573 K. The effects of GeBi2Te4 alloying in PbBi2Te4 (Pb1-xGexBi2Te4, where x ranges from 0.0 to 0.6) were also investigated. Due to alloying-induced point defect scattering and the off-centering effects of Ge2+, the room-temperature lattice thermal conductivity decreased to 0.55 Wm-1K-1 when x = 0.5. Combined with a maintained weighted mobility (ca. 60 cm2V-1s-2), the room-temperature ZT increased to 0.28. This value could further increase to 0.65 with a reduction in lattice thermal conductivity to its lower-limit value. A high ZT of 1.0 is also predicted for pristine PbBi2Te4 at 473 K, demonstrating its potential as a near-room-temperature thermoelectric system.
| Original language | English |
|---|---|
| Pages (from-to) | 10831-10840 |
| Number of pages | 10 |
| Journal | Chemistry of Materials |
| Volume | 36 |
| Issue number | 21 |
| DOIs | |
| State | Published - Nov 12 2024 |
Funding
This study was supported by a grant from the U.S. Department of Energy, Office of Science, and Office of Basic Energy Sciences under Award Number DE-SC0024256 (design, synthesis and physical characterization of materials). It was also supported by the Ministry of Education (MOE) Academic Research Fund (AcRF) Tier 1 (RG128/21 and RT6/22), MOE Tier 2 (MOE-T2EP50223-0003); the Basic Science Center Project of NSFC (Grant No. 52388201), and the National Key R&D Program of China (No. 2023YFB3809400). It also used the EPIC facility of Northwestern University\u2019s NUANCE Center, which received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS 2025633), the MRSEC program (NSF DMR-2308691) at the Materials Research Center, the International Institute for Nanotechnology (IIN), the Keck Foundation, and the State of Illinois. Y.L. acknowledge the computational resource from Quest High Performance Computing Facility at Northwestern University. The research performed at the NOMAD beamlines at ORNL\u2019s Spallation Neutron Source was sponsored by the Scientific User Facilities Division, Office of Basic Sciences, U.S. Department of Energy. L. H. is supported by a JSPS Fellowship for International Research Fellows (No. P19057). Synchrotron radiation experiments were performed at the BL02B2 beamline of SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal No. 2021A1074). The authors also acknowledge the Facility for Analysis, Characterization, Testing, and Simulation, Nanyang Technological University, Singapore, for use of their electron microscopy/X-ray facilities.