Deciphering the ultra-high plasticity in metal monochalcogenides

LW Wong and K Yang and W Han and XD Zheng and HY Wong and CS Tsang and CS Lee and SP Lau and TH Ly and M Yang and J Zhao, NATURE MATERIALS, 23 (2024).

DOI: 10.1038/s41563-023-01788-7

The quest for electronic devices that offer flexibility, wearability, durability and high performance has spotlighted two-dimensional (2D) van der Waals materials as potential next-generation semiconductors. Especially noteworthy is indium selenide, which has demonstrated surprising ultra-high plasticity. To deepen our understanding of this unusual plasticity in 2D van der Waals materials and to explore inorganic plastic semiconductors, we have conducted in-depth experimental and theoretical investigations on metal monochalcogenides (MX) and transition metal dichalcogenides (MX2). We have discovered a general plastic deformation mode in MX, which is facilitated by the synergetic effect of phase transitions, interlayer gliding and micro- cracks. This is in contrast to crystals with strong atomic bonding, such as metals and ceramics, where plasticity is primarily driven by dislocations, twinning or grain boundaries. The enhancement of gliding barriers prevents macroscopic fractures through a pinning effect after changes in stacking order. The discovery of ultra-high plasticity and the phase transition mechanism in 2D MX materials holds significant potential for the design and development of high-performance inorganic plastic semiconductors. The metal monochalcogenides are a group of van der Waals layered semiconductors with ultra-high plasticity. It is now revealed that their plasticity is attributed to the ability to transform their stacking order or phases, coupled with the concurrent generation of a micro-crack network.

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