Unprecedented Superelasticity in Mo₁₇O₄₇/MoS₂ Core-Shell Nanowires

Inorganic materials are usually known with high modulus and brittleness. Here the finding of a [001]-oriented Mo₁₇O₄₇ nanowires (NWs) material is reported with a thin MoS₂ shell that exhibits superelastic deformability superior to the reported inorganic NWs. Three-point bending tests reveal that the elastic modulus of Mo₁₇O₄₇ crystals in the [001] direction is 103 GPa, consistent with the density functional theory (DFT)-predicted results. Furthermore, in situ bending tests via scanning electron microscopy, accomplished with finite element simulations, demonstrate that the NWs can sustain bending strains up to 35% repeatedly without showing appreciable residual deformation. First-principles calculations reveal that this extraordinary superelasticity results from the smooth transformation between the chemical bonding and physical binding (van der Waals) in the [001] direction of Mo₁₇O₄₇ crystal. The remarkable superelasticity of Mo₁₇O₄₇ NWs may offer enormous potential in flexible electronics and photonic devices.