B-C取代包合物中的组分驱动金属-半导体转变与增强的声子输运
Composition-Driven Metal-to-Semiconductor Transition and Enhanced Phonon Transport in B-C substituted Clathrate
- Institute of Physics, Polish Academy of Sciences（波兰科学院物理研究所）
- Institute for Advanced Study, Shenzhen University（深圳大学高等研究院）
- IDEAS Research Institute（IDEAS研究院）
- Department of Physics, University of Alabama at Birmingham（阿拉巴马大学伯明翰分校物理系）
- Institute of Theoretical Physics, Faculty of Physics, University of Warsaw（华沙大学物理学院理论物理研究所）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究通过DFT和机器学习势发现，在BaB3C3包合物中单个B到C取代可打开0.33 eV带隙，实现金属到半导体转变，同时将晶格热导率从7.6提升至18.7 W/mK，增强约2.5倍，为同时调控电子和热输运提供了新策略。
AI中文摘要：
建立同时控制电子结构和热输运的化学设计规则是热管理和能源材料领域长期追求的目标。在此，我们证明单个B到C的取代改变了电子计数，同时重构了键合网络和晶体结构，驱动金属到半导体的转变，同时增强了晶格热导率。利用密度泛函理论（DFT）和机器学习原子间势（MLIPs），我们研究了立方BaB3C3及其B到C取代的正方BaB2C4结构的电子结构、晶格动力学和声子热输运。该取代每化学式单元向B-C框架捐赠一个电子，从而触发强C-C键的形成并打开0.33 eV的带隙。消息传递原子簇展开（MACE）模型重现了DFT能量和力，得到的声子色散和晶格热导率与DFT基准高度一致。热力学稳定的立方BaB3C3在300 K下具有各向同性的晶格热导率7.6 W/mK。用C取代B硬化了声子色散（表现为频率从约800 cm^-1上移至约900 cm^-1），同时提高了声子群速度和寿命。因此，晶格热导率飙升至18.7 W/mK，代表面内分量约2.5倍的显著增强，并从各向同性转变为各向异性行为，其特征为kappa_x = kappa_y > kappa_z。我们的结果表明，最小的B到C取代提供了一种可行的策略来调节电子结构，从而将晶体从金属转变为半导体，并同时增强声子热输运。
英文摘要：
Establishing chemical design rules that simultaneously control the electronic structure and thermal transport is a long-sought goal for heat-management and energy materials. Here, we demonstrate that a single B-to-C substitution changes the electron count and simultaneously reconstructs the bonding network and crystal structure, driving a metal-to-semiconductor transition while concurrently enhancing the lattice thermal conductivity. Using density-functional theory (DFT) and machine-learned interatomic potentials (MLIPs), we investigate the electronic structure, lattice dynamics, and phonon thermal transport in cubic BaB3C3 and its B-to-C-substituted tetragonal BaB2C4 structure. The substitution donates one electron per formula unit to the B-C framework, thereby triggering the formation of strong C-C bonds and opening a bandgap of 0.33 eV. The Message Passing Atomic Cluster Expansion (MACE) model reproduces DFT energies and forces, yielding phonon dispersion and lattice thermal conductivity in excellent agreement with DFT benchmarks. Thermodynamically stable cubic BaB3C3 possesses an isotropic lattice thermal conductivity of 7.6 W/mK at 300 K. Substituting B with C hardens the phonon dispersion (evidenced by a frequency upshift from ~800 to ~900 cm^-1) and simultaneously boosts both phonon group velocities and lifetimes. Consequently, the lattice thermal conductivity surges to 18.7 W/mK, representing a remarkable ~2.5-fold enhancement of the in-plane component and a transformation from isotropic to anisotropic behavior, characterized by kappa_x = kappa_y > kappa_z. Our results demonstrate that minimal B-to-C substitution provides a viable strategy to modulate the electronic structure, thereby transforming the crystal from a metal to a semiconductor and concomitantly enhancing phonon thermal transport.
