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Title: First-principles study of energy and atomic solubility of twinning-associated boundaries in hexagonal metals

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Publication Date:
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
Grant/Contract Number:
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Acta Materialia
Additional Journal Information:
Journal Volume: 85; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-05-18 09:12:07; Journal ID: ISSN 1359-6454
Country of Publication:
United States

Citation Formats

Kumar, Anil, Wang, Jian, and Tomé, Carlos N. First-principles study of energy and atomic solubility of twinning-associated boundaries in hexagonal metals. United States: N. p., 2015. Web. doi:10.1016/j.actamat.2014.11.015.
Kumar, Anil, Wang, Jian, & Tomé, Carlos N. First-principles study of energy and atomic solubility of twinning-associated boundaries in hexagonal metals. United States. doi:10.1016/j.actamat.2014.11.015.
Kumar, Anil, Wang, Jian, and Tomé, Carlos N. 2015. "First-principles study of energy and atomic solubility of twinning-associated boundaries in hexagonal metals". United States. doi:10.1016/j.actamat.2014.11.015.
title = {First-principles study of energy and atomic solubility of twinning-associated boundaries in hexagonal metals},
author = {Kumar, Anil and Wang, Jian and Tomé, Carlos N.},
abstractNote = {},
doi = {10.1016/j.actamat.2014.11.015},
journal = {Acta Materialia},
number = C,
volume = 85,
place = {United States},
year = 2015,
month = 2

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.actamat.2014.11.015

Citation Metrics:
Cited by: 25works
Citation information provided by
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  • Two types of global space-group optimization (GSGO) problems can be recognized in binary metallic alloys A{sub q}B{sub 1-q}: (1) configuration search problems, where the underlying crystal lattice is known and the aim is finding the most favorable decoration of the lattice by A and B atoms and (2) lattice-type search problems, where neither the lattice type nor the decorations are given and the aim is finding energetically favorable lattice vectors and atomic occupations. Here, we address the second, lattice-type search problem in binary A{sub q}B{sub 1-q} metallic alloys, where the constituent solids A and B have different lattice types. Wemore » tackle this GSGO problem using an evolutionary algorithm, where a set of crystal structures with randomly selected lattice vectors and site occupations is evolved through a sequence of generations in which a given number of structures of highest LDA energy are replaced by new ones obtained by the generational operations of mutation or mating. Each new structure is locally relaxed to the nearest total-energy minimum by using the ab initio atomic forces and stresses. We applied this first-principles evolutionary GSGO scheme to metallic alloy systems where the nature of the intermediate A-B compounds is difficult to guess either because pure A and pure B have different lattice types and the (1) intermediate compound has the structure of one end-point (Al{sub 3}Sc, AlSc{sub 3}, CdPt{sub 3}), or (2) none of them (CuPd, AlSc), or (3) when the intermediate compound has lattice sites belonging simultaneously to a few types (fcc, bcc) (PdTi{sub 3}). The method found the correct structures, L1{sub 2} type for Al{sub 3}Sc, D0{sub 19} type for AlSc3, 'CdPt{sub 3}' type for CdPt{sub 3}, B2 type for CuPd and AlSc, and A15 type for PdTi{sub 3}. However, in such stochastic methods, success is not guaranteed, since many independently started evolutionary sequences produce at the end different final structures: one has to select the lowest-energy result from a set of such independently started sequences. Interestingly, we also predict a hitherto unknown (P 2/m) structure of the hard compound IrN{sub 2} with energy lower than all previous predictions.« less
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  • Epitaxial films of BaSi{sub 2} on Si(111) for solar cell applications possess three epitaxial variants and exhibit a minority carrier diffusion length (ca. 9.4 μm) much larger than the domain size (ca. 0.2 μm); thus, the domain boundaries (DBs) between the variants do not act as carrier recombination centers. In this work, transmission electron microscopy (TEM) was used to observe the atomic arrangements around the DBs in BaSi{sub 2} epitaxial films on Si(111), and the most stable atomic configuration was determined by first-principles calculations based on density functional theory to provide possible interface models. Bright-field TEM along the a-axis of BaSi{sub 2}more » revealed that each DB was a twin boundary between two different epitaxial variants, and that Ba{sup (II)} atoms form hexagons containing central Ba{sup (I)} atoms in both the bulk and DB regions. Four possible interface models containing Ba{sup (I)}-atom interface layers were constructed, each consistent with TEM observations and distinguished by the relationship between the Si tetrahedron arrays in the two domains adjacent across the interface. This study assessed the structural relaxation of initial interface models constructed from surface slabs terminated by Ba{sup (I)} atoms or from zigzag surface slabs terminated by Si tetrahedra and Ba{sup (II)} atoms. In these models, the interactions or relative positions between Si tetrahedra appear to dominate the relaxation behavior and DB energies. One of the four interface models whose relationship between first-neighboring Si tetrahedra across the interface was the same as that in the bulk was particularly stable, with a DB energy of 95 mJ/m{sup 2}. There were no significant differences in the partial densities of states and band gaps between the bulk and DB regions, and it was therefore concluded that such DBs do not affect the minority carrier properties of BaSi{sub 2}.« less