Environment-Controlled Dislocation Migration and Superplasticity in Monolayer MoS2.

The two-dimensional (2D) transition metal dichalcogenides (TMDC, of generic formula MX2) monolayer displays the "triple-decker" structure with the chemical bond organization much more complex than in well-studied monatomic layers of graphene or boron nitride. Accordingly, the makeup of the dislocations in TMDC permits chemical variability, depending sensitively on the equilibrium with the environment. In particular, first-principles calculations show that dislocations state can be switched to highly mobile, profoundly changing the lattice relaxation and leading to superplastic behavior. With 2D MoS2 as an example, we construct full map for dislocation dynamics, at different chemical potentials, for both the M- and X-oriented dislocations. Depending on the structure of the migrating dislocation, two different dynamic mechanisms are revealed: either the direct rebonding (RB) mechanism where only a single metal atom shifts slightly, or generalized Stone-Wales (SW(g)) rotation in which several atoms undergo significant displacements. The migration barriers for RB mechanism can be 2-4 times lower than for the SW(g). Our analyses show that within a range of chemical potentials, highly mobile dislocations could at the same time be thermodynamically favored, that is statistically dominating the overall material property. This demonstrates remarkable possibility of changing material basic property such as plasticity by changing elemental chemical potentials of the environment.

[1]  Boris I. Yakobson,et al.  Mechanical relaxation and “intramolecular plasticity” in carbon nanotubes , 1998 .

[2]  Xiaolong Zou,et al.  Predicting dislocations and grain boundaries in two-dimensional metal-disulfides from the first principles. , 2013, Nano letters.

[3]  G. Seifert,et al.  Calculations of molecules, clusters, and solids with a simplified LCAO-DFT-LDA scheme , 1996 .

[4]  Boris I. Yakobson,et al.  Vapor Phase Growth and Grain Boundary Structure of Molybdenum Disulfide Atomic Layers , 2013 .

[5]  G. Kresse,et al.  From ultrasoft pseudopotentials to the projector augmented-wave method , 1999 .

[6]  G. Henkelman,et al.  A climbing image nudged elastic band method for finding saddle points and minimum energy paths , 2000 .

[7]  Qing Hua Wang,et al.  Electronics and optoelectronics of two-dimensional transition metal dichalcogenides. , 2012, Nature nanotechnology.

[8]  E. Akturk,et al.  Mechanical and Electronic Properties of MoS2 Nanoribbons and Their Defects , 2010, 1009.5488.

[9]  J. Nørskov,et al.  Atomic and electronic structure of MoS2 nanoparticles , 2003 .

[10]  Sidney R. Cohen,et al.  On the mechanical behavior of WS2 nanotubes under axial tension and compression. , 2006, Proceedings of the National Academy of Sciences of the United States of America.

[11]  E. Johnston-Halperin,et al.  Progress, challenges, and opportunities in two-dimensional materials beyond graphene. , 2013, ACS nano.

[12]  B. Yakobson,et al.  Pseudoclimb and dislocation dynamics in superplastic nanotubes. , 2007, Physical review letters.

[13]  Wang Yao,et al.  Valley polarization in MoS2 monolayers by optical pumping. , 2012, Nature nanotechnology.

[14]  Blöchl,et al.  Projector augmented-wave method. , 1994, Physical review. B, Condensed matter.

[15]  Andras Kis,et al.  Stretching and breaking of ultrathin MoS2. , 2011, ACS nano.

[16]  A. Zunger,et al.  CORRIGENDUM: Momentum-space formalism for the total energy of solids , 1979 .

[17]  Jun Lou,et al.  Vapour phase growth and grain boundary structure of molybdenum disulphide atomic layers. , 2013, Nature materials.

[18]  Pinshane Y. Huang,et al.  Grains and grain boundaries in single-layer graphene atomic patchwork quilts , 2010, Nature.

[19]  J. Shan,et al.  Experimental demonstration of continuous electronic structure tuning via strain in atomically thin MoS2. , 2013, Nano letters.

[20]  Jian‐Hao Chen,et al.  Atomic resolution imaging of grain boundary defects in monolayer chemical vapor deposition-grown hexagonal boron nitride. , 2013, Journal of the American Chemical Society.

[21]  Xiaolong Zou,et al.  An open canvas--2D materials with defects, disorder, and functionality. , 2015, Accounts of chemical research.

[22]  L. Tapasztó,et al.  Breakdown of continuum mechanics for nanometre-wavelength rippling of graphene , 2012, Nature Physics.

[23]  G. Scuseria,et al.  Thermodynamics of yield in boron nitride nanotubes , 2003 .

[24]  J. Shan,et al.  Tightly bound trions in monolayer MoS2. , 2012, Nature materials.

[25]  Burke,et al.  Generalized Gradient Approximation Made Simple. , 1996, Physical review letters.

[26]  Simon Kurasch,et al.  From point to extended defects in two-dimensional MoS2: Evolution of atomic structure under electron irradiation , 2013 .

[27]  Keliang He,et al.  Control of valley polarization in monolayer MoS2 by optical helicity. , 2012, Nature nanotechnology.

[28]  Timothy C. Berkelbach,et al.  Grains and grain boundaries in highly crystalline monolayer molybdenum disulphide. , 2013, Nature Materials.

[29]  Seifert,et al.  Construction of tight-binding-like potentials on the basis of density-functional theory: Application to carbon. , 1995, Physical review. B, Condensed matter.

[30]  T. Frauenheim,et al.  DFTB+, a sparse matrix-based implementation of the DFTB method. , 2007, The journal of physical chemistry. A.

[31]  W. Regan,et al.  Grain boundary mapping in polycrystalline graphene. , 2011, ACS nano.

[32]  G. Seifert,et al.  Theoretical Study of the Mechanical Behavior of Individual TiS2 and MoS2 Nanotubes , 2012 .

[33]  Jing Kong,et al.  Intrinsic structural defects in monolayer molybdenum disulfide. , 2013, Nano letters.

[34]  U. Kaiser,et al.  Atomic scale study of the life cycle of a dislocation in graphene from birth to annihilation , 2013, Nature Communications.

[35]  Xiaofeng Qian,et al.  Strain-engineered artificial atom as a broad-spectrum solar energy funnel , 2012, Nature Photonics.

[36]  Feliciano Giustino,et al.  Dislocation-Driven Deformations in Graphene , 2012, Science.

[37]  Steven G. Louie,et al.  Topological defects in graphene: Dislocations and grain boundaries , 2010, 1004.2031.

[38]  Jed I. Ziegler,et al.  Bandgap engineering of strained monolayer and bilayer MoS2. , 2013, Nano letters.

[39]  Yong-Wei Zhang,et al.  Quasiparticle band structures and optical properties of strained monolayer MoS 2 and WS 2 , 2012, 1211.5653.

[40]  Francisco Guinea,et al.  Local strain engineering in atomically thin MoS2. , 2013, Nano letters.

[41]  Kresse,et al.  Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. , 1996, Physical review. B, Condensed matter.

[42]  M. Dresselhaus,et al.  Superplastic carbon nanotubes , 2006, Nature.

[43]  C. N. Lau,et al.  Controlled ripple texturing of suspended graphene and ultrathin graphite membranes. , 2009, Nature nanotechnology.

[44]  H. C. Andersen.  Molecular dynamics simulations at constant pressure and/or temperature , 1980 .

[45]  B. Yakobson,et al.  Cones, pringles, and grain boundary landscapes in graphene topology. , 2010, Nano letters.

[46]  A. Krasheninnikov,et al.  Atom-by-atom observation of grain boundary migration in graphene. , 2012, Nano letters.

[47]  Intrinsic magnetism of grain boundaries in two-dimensional metal dichalcogenides. , 2013, ACS nano.

[48]  S. Iijima,et al.  Imaging active topological defects in carbon nanotubes. , 2007, Nature nanotechnology.

[49]  Traian Dumitrica,et al.  Symmetry-, time-, and temperature-dependent strength of carbon nanotubes. , 2006, Proceedings of the National Academy of Sciences of the United States of America.

[50]  G. Kresse,et al.  Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set , 1996 .

[51]  Xiaolong Zou,et al.  Dislocations and grain boundaries in two-dimensional boron nitride. , 2012, ACS nano.

[52]  O. Cretu,et al.  Evidence for active atomic defects in monolayer hexagonal boron nitride: a new mechanism of plasticity in two-dimensional materials. , 2014, Nano letters.

[53]  Aaron M. Jones,et al.  Electrical control of neutral and charged excitons in a monolayer semiconductor , 2012, Nature Communications.

[54]  G. Scuseria,et al.  Mechanically induced defects and strength of BN nanotubes , 2002 .

[55]  Ji Feng,et al.  Valley-selective circular dichroism of monolayer molybdenum disulphide , 2012, Nature Communications.

[56]  Georg Kresse,et al.  Shape and Edge Sites Modifications of MoS2 Catalytic Nanoparticles Induced by Working Conditions: A Theoretical Study , 2002 .

[57]  Gustavo E Scuseria,et al.  Scratching the surface of buckminsterfullerene: the barriers for Stone-Wales transformation through symmetric and asymmetric transition states. , 2003, Journal of the American Chemical Society.