  Thermally stimulated process such as evaporation, phase transition, or
solid-liquid transition of a solid consumes each a certain portion of the solid
cohesive energy that is the sum of bond energy over all the coordinates of all
the involved atoms. Generally, the critical temperatures for such processes
drop with solid size, unless hetero capping or interfacial interaction becomes
dominant, because of the increased portion of the lower-coordinated surface
atoms [Sun et al., J. Phys. Chem. B108, 1080 (2004)]. It is intriguing,
however, that the melting point (Tm) of a solid containing III-A or IV-A atoms
oscillates with size (the Tm drops first and then rises as the solid size is
reduced) and that the Tm of chemically capped nanosolid often increases with
the inverse size. Here we show that bond nature evolution is essential for the
selective nanosolids and at the junction interfaces, which is responsible for
the superheating of the smallest nanosolids, chemically capped clusters, and
junction interfaces that exhibit insulating nature with high mechanical
strength.
