A comparative study of Sm networks in Al-10 at.%Sm glass and associated crystalline phases

Abstract

The Al-Sm system is selected as a model system to study the transition process from liquid and amorphous to crystalline states. In recent work, we have shown that, in addition to long-range translational periodicity, crystal structures display well-defined short-range local atomic packing motifs that transcends liquid, amorphous and crystalline states. In this paper, we investigate the longer-range spatial packing of these short-range motifs by studying the interconnections of Sm-Sm networks in different amorphous and crystalline samples obtained from molecular dynamics simulations. In our analysis, we concentrate on Sm-Sm distances in the range ~ 5.0 − 7.2 Å, corresponding to Sm atoms in the second and third shells of Sm-centered clusters. We discover a number of empirical rules characterizing the evolution of Sm networks from the liquid and amorphous states to associated metastable crystalline phases experimentally observed in the initial stages of devitrification of different amorphous samples. As direct simulation of glass formation is difficult because of the vast difference between experimental quench rates and what is achievable on the computer, we hope these rules will be helpful in building a better picture of structural evolution during glass formation as well as a more detailed description of phase selection and growth during devitrification.

Phase Diagram and Structure Map of Binary Nanoparticle Superlattices from a Lennard-Jones Model

“…As found for MgZn 2 and Z 16 , the regions for stability and metastability are wider than the corresponding structures, thus indicating that motifs define very general families of structures, like Laves phases. A classification of motifs by renormalized angle sequences 38,39 has been included in the Supporting Information. This study has identified 53 equilibrium lattices and 42 motifs (with the larger particle A as reference).…”

Phase Diagram and Structure Map of Binary Nanoparticle Superlattices from a Lennard-Jones Model

“…As found for MgZn 2 and Z 16 , the regions for stability and metastability is wider than the corresponding structures, thus indicating that motifs define very general families of structures, like Laves phases. A classification of motifs by Renormalized Angle Sequences (RAS) [40,41] has been included in Supporting Information.…”