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

Low-melting-point metal nanoparticles show remarkable undercoolings: exceptional values Delta T/T-m congruent to 0.5 were previously reported for confined Ga droplets in the 100-1000 nm range. This was considered a characteristic limiting temperature for Ga. We here give evidence that Ga nanoparticles in the 3-15 nm range can be undercooled at least down to 90 K (Delta T/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.