Exceptional plasticity in defective Bi₂Te₃-based TE crystals [IMAGE: SICCAS]

Chinese scientists have realized important progress on the plasticization of inorganic thermoelectric semiconductors. This study, which was conducted by Professor Shi Xun’s and Professor Chen Lidong’s team from the Shanghai Institute of Ceramics of the Chinese Academy of Sciences (SICCAS), cooperating with the scientists from the Hangzhou Institute for Advanced Study and Shanghai Jiao Tong University, was published online in Science on December 6, 2024. (https://www.science.org/doi/10.1126/science.adr8450)

Inorganic semiconductors have abundant functionalities with high carrier mobility and good stability crucial for modern electronics industry. However, they are usually brittle, which greatly limits their application in flexible and deformable electronics. The recently discovered metal-like room-temperature plasticity/ductility in some inorganic semiconductors has revolutionized our understanding of material’s physical properties. Despite this, such types of plastic/ductile inorganic semiconductors are still very rare.

High-density, diverse microstructures in plastic Bi₂Te₃ crystal [IMAGE: SICCAS]

This study focuses on Bi₂Te₃-based thermoelectric semiconductors, showcasing how defects, especially antisite defects, can lead to high-density, diverse microstructures to substantially influence mechanical properties and thus successfully transform these bulk semiconductors from brittle to plastic.

Bi2Te3-based semiconductors are the best TE materials near room temperature, making them indispensable for applications like solid-state refrigeration, precise temperature control, and local thermal management. Despite their thermal advantages, these materials are usually brittle and prone to break under mechanical loading.

Molecular dynamic simulations for defective Bi₂Te₃ crystal [IMAGE: SICCAS]

Interestingly, the research team found that Bi₂Te₃ bulk single crystals with the Bi:Te of 2.00:2.96 grown by using the temperature gradient method, demonstrate extraordinary room-temperature plasticity. They can endure more than 20 percent, 8 percent, and 80 percent strains in the three-point bending, uniaxial tensile, and compression tests, respectively. These values are comparable with those of good plastic semiconductors and far larger than that in polycrystalline Bi₂Te₃-based materials.

The microstructure characterizations and molecular dynamic simulations indicate that the high-density, diverse microstructures (e.g. line defects: dislocation and ripplocation; planar defects: swapped-bilayer and hyperdislocation; and lattice distortions) induced by the coexistence of antisite Bi_Te and Te_Bi defects are responsible for the extraordinary room-temperature plasticity. These high-density, diverse microstructures can facilitate the inter- and cross-layer slipping while maintaining structural integrity during deformation, to successfully transform the bulk semiconductors from brittle to plastic.

Likewise, the plastic defective Bi₂Te₃-based crystals also possess excellent thermoelectric performance, boosting the room-temperature zT of plastic thermoelectric semiconductors to 1.05, which is comparable with the best brittle thermoelectric semiconductors.

This groundbreaking work not only provides a novel high-performance plastic inorganic thermoelectric material but also proposes an effective strategy for transforming brittle materials into plastic ones, offering valuable insights for the plasticization of brittle inorganic non-metallic materials.

For more information, please contact:

Dr. Qiu Pengfei

E-mail: qiupf@mail.sic.ac.cn

Dr. Shi Xun

E-mail: xshi@mail.sic.ac.cn

Dr. Chen Lidong

E-mail: cld@mail.sic.ac.cn

Shanghai Institute of Ceramics,

Chinese Academy of Sciences

Source: Shanghai Institute of Ceramics,

Chinese Academy of Sciences