First-principles study of epitaxial strain as a method of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mtext>B</mml:mtext><mml:mn>4</mml:mn><mml:mo>→</mml:mo><mml:mtext>B</mml:mtext><mml:mtext>C</mml:mtext><mml:mtext>T</mml:mtext></mml:mrow></mml:math>stabilization in ZnO, ZnS, and CdS

Morgan, Benjamin J.

doi:10.1103/physrevb.82.153408

Cited by 27 publications

(7 citation statements)

References 26 publications

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“…Our calculated equilibrium volume (26.1 Å 3 /ZnO) and relative stability (0.05 eV/ZnO less stable than the wurtzite structure) agree very well with results of Morgan 29 and Zwijnenburg et al 30 However, the results are considerably different from the equilibrium volume (33 Å 3 /ZnO) and relative stability (1.15 eV/ZnO less stable than wurtzite) reported by Zhang et al, 33 who performed similar PBE calculations and suggested that the cubane polymorph is the most stable low-density polymorph of ZnO. In contrast to the results of Zhang et al, 33 our calculations show that the BCT structure in fact is more stable than the cubane structure.…”

Section: Resultssupporting

confidence: 87%

An SCC-DFTB Repulsive Potential for Various ZnO Polymorphs and the ZnO–Water System

et al. 2013

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We have developed an efficient scheme for the generation of accurate repulsive potentials for self-consistent charge density-functional-based tight-binding calculations, which involves energy-volume scans of bulk polymorphs with different coordination numbers. The scheme was used to generate an optimized parameter set for various ZnO polymorphs. The new potential was subsequently tested for ZnO bulk, surface, and nanowire systems as well as for water adsorption on the low-index wurtzite (101̅0) and (112̅0) surfaces. By comparison to results obtained at the density functional level of theory, we show that the newly generated repulsive potential is highly transferable and capable of capturing most of the relevant chemistry of ZnO and the ZnO/water interface.

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Section: Resultssupporting

confidence: 87%

An SCC-DFTB Repulsive Potential for Various ZnO Polymorphs and the ZnO–Water System

et al. 2013

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“…5 and 6, where the atomic structure before any axial loading is applied is shown for both the [0110] and [2110] orientations. Specifically, it is shown that for both the [0110] and [2110] orientations, if no surface treatment is performed, as has been the case in previous calculations [45,44,43], the WZ lattice structure is unstable and transforms to a d-BCT structure. In fact, this transformation occurs during the initial relaxation phase of the simulation for all NW sizes we have considered, and therefore the Young's moduli for the [0110] and [2110] orientations in Fig.…”

Section: Mechanical Propertiesmentioning

confidence: 80%

Surface effects on the piezoelectricity of ZnO nanowires

Dai

Park

2013

Journal of the Mechanics and Physics of Solids

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We utilize classical molecular dynamics to study surface effects on the piezoelectric properties of ZnO nanowires as calculated under uniaxial loading. An important point to our work is that we have utilized two types of surface treatments, those of charge compensation and surface passivation, to eliminate the polarization divergence that otherwise occurs due to the polar (0001) surfaces of ZnO. In doing so, we find that if appropriate surface treatments are utilized, the elastic modulus and the piezoelectric properties for ZnO nanowires having a variety of axial and surface orientations are all reduced as compared to the bulk value as a result of polarization-reduction in the polar [0001] direction. The reduction in effective piezoelectric constant is found to be independent of the expansion or contraction of the polar (0001) surface in response to surface stresses. Instead, the surface polarization and thus effective piezoelectric constant is substantially reduced due to a reduction in the bond length of the Zn-O dimer closest to the polar (0001) surface. Furthermore, depending on the nanowire axial orientation, we find in the absence of surface treatment that the piezoelectric properties of ZnO are either effectively lost due to unphysical transformations from the wurtzite to non-piezoelectric d-BCT phases, or also become smaller with decreasing nanowire size. The overall implication of this study is that if enhancement of the piezoelectric properties of ZnO is desired, then continued miniaturization of square * Electronic address: parkhs@bu.edu arXiv:1210.5435v1 [cond-mat.mtrl-sci] 19 Oct 2012 or nearly square cross section ZnO wires to the nanometer scale is not likely to achieve this result.

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“…This is different from the previous results of ZnS [19]: where c 44 always decreases and eventually reaches zero. As the tensile 11 . When 33 > 0.16 and −0.16 < 33 < −0.10, C < 0, indicating the structural instability.…”

Section: Resultsmentioning

confidence: 99%

“…Such lattice mismatching leads either to biaxial strain in the (0001) plane or uniaxial strain along the [0001] direction. First of all, the hexagonal structure is easily modified by the strain: an intermediate graphite-like phase between wurtzite and rocksalt has been observed [5][6][7][8][9][10][11][12][13][14][15][16]. The new phase, with the P6 3 /mmc space group, shows fivefold coordination bonding (wurtzite shows fourfold and rocksalt sixfold coordination).…”

Section: Introductionmentioning

confidence: 99%

Phase transition and band-structure tuning in InN through uniaxial and biaxial strains

Duan

Qin

Shi

et al. 2013

J. Phys.: Condens. Matter

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The phase transitions and band structure of InN under uniaxial and biaxial strains are systematically investigated using first-principles calculations. The main findings are summarized as follows: (I) although graphite-like phases are observed for both types of strain, the phase transitions are drastically different: second order for uniaxial strain and first order for biaxial strain. Furthermore, the second-order transition is driven by elastic and dynamical instabilities, whereas the first-order transition is driven only by elastic instability. (II) The wurtzite bandgap is always direct and that of the graphite-like phase is always indirect. Furthermore, the wurtzite bandgap is drastically enhanced by compressive uniaxial strain but reduced by tensile uniaxial strain. However, both biaxial strains greatly reduce the bandgap and eventually the semi-metallic phases are achieved.

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First-principles study of epitaxial strain as a method ofB4→BCTstabilization in ZnO, ZnS, and CdS

Cited by 27 publications

References 26 publications

An SCC-DFTB Repulsive Potential for Various ZnO Polymorphs and the ZnO–Water System

An SCC-DFTB Repulsive Potential for Various ZnO Polymorphs and the ZnO–Water System

Surface effects on the piezoelectricity of ZnO nanowires

Phase transition and band-structure tuning in InN through uniaxial and biaxial strains

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