Misawa Masaaki, Hokyo Hinata, Fukushima Shogo, Shimamura Kohei, Koura Akihide, Shimojo Fuyuki, Kalia Rajiv K, Nakano Aiichiro, Vashishta Priya
Faculty of Natural Science and Technology, Okayama University, Okayama, 700-8530, Japan.
Department of Physics, Kumamoto University, Kumamoto, 860-8555, Japan.
Sci Rep. 2022 Nov 14;12(1):19458. doi: 10.1038/s41598-022-24004-z.
Typical ductile materials are metals, which deform by the motion of defects like dislocations in association with non-directional metallic bonds. Unfortunately, this textbook mechanism does not operate in most inorganic semiconductors at ambient temperature, thus severely limiting the development of much-needed flexible electronic devices. We found a shear-deformation mechanism in a recently discovered ductile semiconductor, monoclinic-silver sulfide (AgS), which is defect-free, omni-directional, and preserving perfect crystallinity. Our first-principles molecular dynamics simulations elucidate the ductile deformation mechanism in monoclinic-AgS under six types of shear systems. Planer mass movement of sulfur atoms plays an important role for the remarkable structural recovery of sulfur-sublattice. This in turn arises from a distinctively high symmetry of the anion-sublattice in AgS, which is not seen in other brittle silver chalcogenides. Such mechanistic and lattice-symmetric understanding provides a guideline for designing even higher-performance ductile inorganic semiconductors.
典型的韧性材料是金属，它们通过诸如位错等缺陷的运动以及无方向性的金属键发生变形。不幸的是，这种教科书式的机制在大多数无机半导体的室温条件下并不起作用，从而严重限制了急需的柔性电子器件的发展。我们在最近发现的一种韧性半导体——单斜硫化银（AgS）中发现了一种剪切变形机制，这种机制无缺陷、全方位且能保持完美的结晶度。我们的第一性原理分子动力学模拟阐明了单斜AgS在六种剪切系统下的韧性变形机制。硫原子的平面质量运动对于硫亚晶格显著的结构恢复起着重要作用。这反过来又源于AgS中阴离子亚晶格独特的高对称性，而在其他脆性银硫属化合物中并未观察到这种对称性。这种对机制和晶格对称性的理解为设计性能更高的韧性无机半导体提供了指导。
