Extreme undercooling (down to 90 K) of liquid metal nanoparticles

Low-melting-point metal nanoparticles show remarkable undercoolings: exceptional values ΔT /T_m≅0.5 were previously reported for confined Ga droplets in the 100-1000nm range. This was considered a characteristic limiting temperature for Ga. We here give evidence that Ga nanoparticles in the 3-15nm range can be undercooled at least down to 90K (ΔT/T_m⩾0.7) without crystallization. Since computations and experiments on clusters with <50 atoms show on the contrary the signatures of melting at temperatures well above the bulk value, the result is particularly relevant in stressing the importance of interfacial and finite-size effects on the thermodynamics of the nanoscale.