Can every substance exist as an amorphous solid?

Many substances can exist as amorphous solids, but it is an open question whether or not all substances can be put into the amorphous form. It has been proposed that the demonstration of pure amorphous argon is the most convincing evidence for the universality of the amorphous state. However, theoretical studies have shown that a non-crystalline structure made by quenching liquid argon is not a solid, for it crystallizes immediately. Here, we demonstrate that amorphous argon model containing triple-shell icosahedral clusters can exist for more than one day below 7 K, supporting the universality of the amorphous state. Our findings open new perspectives not only for making amorphous solids of substances such as pure noble gases and fcc metals which have not yet been put into the amorphous form but also for enhancing the stability of existing amorphous solids.