Liquid-like behaviours of metallic glassy nanoparticles at room temperature

Abstract

Direct atomic-scale observations and measurements on dynamics of amorphous metallic nanoparticles (a-NPs) are challenging owing to the insufficient consciousness to their striking characterizations and the difficulties in technological approaches. In this study, we observe coalescence process of the a-NPs at atomic scale. We measure the viscosity of the a-NPs through the particles coalescence by in situ method. We find that the a-NPs have fast dynamics, and the viscosity of the a-NPs exhibits a power law relationship with size of the a-NPs. The a-NPs with sizes smaller than 3 nm are in a supercooled liquid state and exhibit liquid-like behaviours with a decreased viscosity by four orders of magnitude lower than that of bulk glasses. These results reveal the intrinsic flow characteristics of glasses in low demension, and pave a way to understand the liquid-like behaviours of low dimension glass, and are also of key interest to develop size-controlled nanodevices.

Nanoscale materials often exhibit size-dependent behaviour. Here, the authors use electron microscopy to quantitatively study the size-related dynamics of amorphous metallic nanoparticles, finding that particles below a critical size are in a supercooled liquid state at room temperature, with a viscosity much lower than that of bulk glasses.