Self-organization of amorphous Q-carbon and Q-BN nanoballs

This paper reports for the first time the formation and self-organization of amorphous Q-carbon and Q-BN nanoballs. This is accomplished by nanosecond laser melting of carbon and BN layers, respectively, in a highly undercooled state and subsequent rapid cooling at normal pressures in air. The size of these Q-carbon and Q-BN nanoballs having a uniform size can be varied from 5 to 100 nm, and self-organized along rings and strings by manipulating laser, carbon film, and substrate parameters. It is envisaged that self-organization is promoted by the undercooling and it occurs along strings and rings, which are formed by the tetrahedral alignment in < 100 > and < 110 > directions, respectively. These nanoballs were characterized by HRSEM/TEM/STEM/EELS and Raman to confirm the phase purity and bonding characteristics. The Q-carbon balls exhibit robust ferromagnetism and field emission in pure and undoped form and show highest BCS superconducting transition temperature upon doping with boron. The ferromagnetism in Q-carbon balls can be varied with size and achieve higher coercively than thin films, and these balls can be coated with drugs for targeted delivery. In view of these properties, nanoballs are expected to find novel applications ranging from targeted delivery to nanosensing and superconducting qubits. (c) 2022 Elsevier Ltd. All rights reserved.

Automated summary

This paper reports the formation and self-organization of amorphous Q-carbon and Q-BN nanoballs, and discusses their properties and potential applications.