Achieving Controllable Liquid-Solid Phase Transitions in Metallic Nanoparticles Through Electron Beam Irradiation.

Nano-additive manufacturing (NAM) endows the prospection to build complex 3D nano-sized structures with high flexibility, however it requires manipulating the liquid-solid phase transition at nano-scale resolution, which remains a great challenge. In this study, we realized controllable liquid-solid reversible phase transition of metallic nanoparticles by using electron beam irradiation. Alternating melting and crystallization were induced in Sn and In-Sn nanoparticles at the room temperature by applying an appropriate electron dose rate. For Sn nanoparticles, the temporal fraction of crystalline states can be quantitatively tuned from 1.41% to 90.58% by varying the dose rate from 2.21 × 105 to 0.66 × 105 A/m2, while the crystallization cycles increase from 11 to 26 and then decrease to 3. Similar behaviors were realized in the In-Sn system as well. This tunability enables precise control of the melting and crystallization behavior of an individual metallic nanoparticle by adjusting the electron dose rate. A quantitative thermal model is proposed that phase-dependent particle-substrate thermal conductance controls the balance between beam-induced heating and substrate heat dissipation, leading to temperature oscillations across the phase-transition threshold and enabling reversible melting-crystallization behavior.