Abstract
We report on crystal growth and physical properties of the quasi-one-dimensional compound by combining crystal structure, electrical resistivity, magnetic properties, Seebeck coefficient, Hall coefficient as well as hydrostatic pressure effect up to 11.5 GPa. Unlike -type crystals, the maximum size of high-quality -type crystals can reach 2–3 mm by optimizing the chemical vapor transport method. The measurement results indicate that is a diamagnetic semiconductor with two thermal activation energies, a large one eV and a small one eV, a huge room-temperature Seebeck coefficient of −1000 µV/K, and improved thermoelectric power factor owing to the enhanced electrical conductivity. Under pressure, undergoes a semiconductor-to-metal transition, and the thermal activation energy continuously decreases to almost zero near a critical pressure of 4.25 GPa. Accompanying this process, a density-wave-like transition emerges, characterized by the reversible jump observed in the temperature dependence of the resistivity. As the pressure further increases, the resistivity undergoes a crossover from a Fermi metal to a low-temperature upturn below a characteristic temperature, which decreases from 81 K at 4.5 GPa to 37 K at 11.5 GPa. The upturn in resistivity has a linear dependence on the logarithmic temperature, but does not saturate at low temperatures, which basically excludes a Kondo-like state and indicates the possibility of Anderson weak localization. High-pressure synchrotron x-ray diffraction confirms the absence of structural transition for GPa at room temperature, supporting pressure-induced electronic transition. Our density functional theory calculation on the assumption that the Bi1 occupies an average of contradicts experimental electron bands, indirectly indicating that Bi1 should be partially ordered and has many vacancies in . Our results provide good examples for studying the mechanism of semiconductor metallization and exploring thermoelectric functional properties in low-dimensional materials.
3 More- Received 21 November 2023
- Revised 2 February 2024
- Accepted 26 March 2024
DOI:https://doi.org/10.1103/PhysRevB.109.144107
©2024 American Physical Society