Fundamental Link between ß Relaxation, Excess Wings, and Cage-Breaking in Metallic Glasses.
J Phys Chem Lett
; 9(19): 5877-5883, 2018 Oct 04.
Article
em En
| MEDLINE
| ID: mdl-30240226
ABSTRACT
In glassy materials, the Johari-Goldstein secondary (ß) relaxation is crucial to many properties as it is directly related to local atomic motions. However, a long-standing puzzle remains elusive why some glasses exhibit ß relaxations as pronounced peaks while others present as unobvious excess wings? Using microsecond atomistic simulation of two model metallic glasses (MGs), we demonstrate that such a difference is associated with the number of string-like collective atomic jumps. Relative to that of excess wings, we find that MGs having pronounced ß relaxations contain larger numbers of such jumps. Structurally, they are promoted by the higher tendency of cage-breaking events of their neighbors. Our results provide atomistic insights for different signatures of the ß relaxation that could be helpful for understanding the low-temperature dynamics and properties of MGs.
Texto completo:
1
Base de dados:
MEDLINE
Idioma:
En
Ano de publicação:
2018
Tipo de documento:
Article