Evaluating the ability to form single crystal

Abstract

Design of crystal materials requires predicting the ability of bulk materials to form single crystals, challenging current theories of material design. By introducing a concept of condensing potential (CP), it is shown via vast simulations of crystal growth for fcc (Ni, Cu, Al, Ar) and hcp (Mg), that materials with larger CP can grow into perfect single crystal more easily. Due to the simplicity of the calculation of CP, this method might prove a convenient way to evaluate the ability of materials to form single crystal.

Doping influence on the ability to form single crystals

“…The basic idea of the CP model for single-component systems has been detailed in our previous Letter [18], and is to be briefly summarized as follows. In the process of single crystal growth, the melt (or gaseous) atoms move on a liquid-solid crystal surface and feel simultaneously a vertical (Z direction) potential valley and many parallel (X-Y plane) potential valleys, and finally locate at the valley bottom that corresponds approximately to the ideal lattice site.…”

“…In order to extend our previous CP model [18] from single-component systems to two-component ones, it needs firstly to extend the definitions of CP and fault degree (FD) that evaluates the quality of newly grown crystals. …”

“…FD introduced in our previous work [18] is used to evaluate the qualities of the newly grown crystals, defined as…”

“…Recently, we proposed a condensing potential (CP) model to evaluate the ability of materials to form single crystals, and demonstrated that the ability of forming some single-component crystals (Ni, Al, Cu, Ar and Mg) increases monotonically with increasing CP [18]. Since the prediction can be easily performed via common ab initio methods, the theory should be extended to predict the ability of multi-component materials to form single crystals, which are more common in practice.…”

“…In the present work, we extended the CP model [18] to twocomponent systems, and particularly investigated the Al doping (0-6 wt.%) influence on the crystallizing ability of Ni-based crystal and the Au doping (6, 17, 30 wt.%) influence on the crystallizing ability of Cu-based crystal. Extensive MD simulations were performed to examine the crystal growth and the results showed that the Al doping of only 6 wt.% will considerably decrease the crystallizing ability of pure Ni crystal, which is in contrast with the conventional solid solution point of view that the Al atoms substitute for Ni atoms in the Ni lattice so well that the doping will not affect the crystal growth.…”