Reversible Wurtzite–Tetragonal Reconstruction in ZnO(10$\bar 1$0) Surfaces

He, Mo‐Rigen; Yu, Rong; Zhu, Jing

doi:10.1002/anie.201202598

Cited by 42 publications

(30 citation statements)

References 36 publications

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“…Fortunately, the advent of modern in situ high-resolution transmission electron microscopy (HRTEM), combined with image processing technique, enables probing the mechanism behind complicated physicochemical processes at the atomic scale. For example, nowadays novel phase formation 30 , 31 and transition 32 , 33 , metal-catalyzed process 34 , deformation twinning generation 35 , irradiation-induced void formation 36 as well as nanocrystal facet development 37 have been captured in real-time observations.…”

Section: Introductionmentioning

confidence: 99%

In situ atomic-scale observation of oxidation and decomposition processes in nanocrystalline alloys

et al. 2018

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Oxygen contamination is a problem which inevitably occurs during severe plastic deformation of metallic powders by exposure to air. Although this contamination can change the morphology and properties of the consolidated materials, there is a lack of detailed information about the behavior of oxygen in nanocrystalline alloys. In this study, aberration-corrected high-resolution transmission electron microscopy and associated techniques are used to investigate the behavior of oxygen during in situ heating of highly strained Cu–Fe alloys. Contrary to expectations, oxide formation occurs prior to the decomposition of the metastable Cu–Fe solid solution. This oxide formation commences at relatively low temperatures, generating nanosized clusters of firstly CuO and later Fe2O3. The orientation relationship between these clusters and the matrix differs from that observed in conventional steels. These findings provide a direct observation of oxide formation in single-phase Cu–Fe composites and offer a pathway for the design of nanocrystalline materials strengthened by oxide dispersions.

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Section: Introductionmentioning

confidence: 99%

In situ atomic-scale observation of oxidation and decomposition processes in nanocrystalline alloys

et al. 2018

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“…Since the former effect has no dependence on the direction of the electric field and it only causes symmetric electromechanical responses for positive and negative voltages, the asymmetric electromechanical property of WZ NWs along 〈0001〉 directions we observed is attributed to the latter effect. HRTEM images captured by a spherical aberration corrected TEM using negative spherical aberration imaging technique indicate that 〈0001〉 oriented WZ InAs NWs tested by us were grown along [0001] direction (Figure d,e, see also Figure S8 in the Supporting Information). When a [0001] oriented WZ InAs NW is stretched along its axis, the relative displacement of In 3+ with respect to As 3− results in net negative or positive ionic charges at its two ends and a piezoelectric field along [0001] direction will be built.…”

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confidence: 99%

Remarkable and Crystal‐Structure‐Dependent Piezoelectric and Piezoresistive Effects of InAs Nanowires

Wei

et al. 2015

Advanced Materials

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a promising material exhibiting the piezotronic effect in high frequency electronics and the piezo-phototronic effect in nearinfrared wavelength. However, to date, the piezoelectric effect of InAs NWs has never been demonstrated experimentally.Due to usually anisotropic piezoelectric and piezoresistive effects of semiconductors, the changes of the electrical properties of a semiconductor NW are expected to strongly depend on its crystal structures when mechanical stress is applied. To fi gure out the crystal structures exhibiting maximum electromechanical responses, it is important to establish the relationship between electromechanical properties of semiconductor NWs and NW crystal structures. As compared to bulk semiconductors, semiconductor NWs have been shown to exhibit additional features due to low dimensionality and high surface-to-volume ratio, e.g., quantum confi nement, [ 16 ] surface charge accumulation or depletion, [ 17 ] enhanced surface scattering of carriers, [ 18 ] etc. The high complexities of these effects increase the diffi culty in unambiguously resolving the electromechanical properties of semiconductor NWs in theory, implying the importance to reveal them in experiments. Even though remarkable electromechanical responses to axial strain has hitherto been experimentally demonstrated for the NWs of many semiconductors including ZnO, [ 2,[5][6][7]19 ] Si, [20][21][22][23][24][25][26][27] Ge, [ 28 ] SiC, [ 29 ] etc., none of them has been studied in experiments to establish the relationship between their electromechanical properties and NW crystal structures.In this paper, we in situ study the electromechanical properties of individual InAs NWs grown along different crystallographic directions under axial stretching inside a scanning electron microscope (SEM) and determine the crystal structures of the studied NWs by transmission electron microscopy (TEM). The capability of determining electromechanical properties of InAs NWs together with their crystal structures enables us to establish the relationship between them. Electrical conductance of single-crystalline 〈0001〉 oriented WZ NWs is observed to increase remarkably and asymmetrically for positive and negative bias voltages with tensile strain with an electromechanical gauge factor as large as 2820, which is attributed to the coexistence of remarkable piezoelectric and piezoresistive effects in the NWs. However, single-crystalline 〈 〉 1120 oriented WZ NWs and 〈011〉, 〈103〉, and 〈 〉 211 oriented zinc-blende (ZB) NWs are found to exhibit negligible piezoelectric and piezoresistive effects and the piezoelectric effect in single-crystalline 〈0001〉 oriented WZ NWs is signifi cantly suppressed by stacking faults, experimentally demonstrating the crystal-structure-dependent piezoelectric and piezoresistive effects of InAs NWs.Figure 1 a,b shows the SEM images of two InAs NW samples we study. NWs in Figure 1 a are vertically grown on a Si substrate with a diameter around ≈10 nm and exclusively exhibit single-crystalline WZ structure grown along 〈0001...

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“…The lack of (0001) basal plane trigonal symmetry in BCT-ZnO, however, is incompatible with epitaxial growth on (111) surfaces of fcc metals [6] and other substrates would be required [9]. Although BCT-ZnO is not a likely competing phase in experiments where layered-ZnO has thus far been observed, its relevance as a structural modification is highlighted by its observation at reconstructed ZnO (101-0) surfaces [10] and, as a predicted phase in strained wz-ZnO nanorods [11]. Considerably expanding the handful of previously considered nanofilm polymorphs, we report over 20 ZnO polymorphs in both nanofilm and bulk form providing us with an unprecedented overview of the (nano) structural and energetic possibilities of this important material.…”

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confidence: 99%

Nanofilm versus Bulk Polymorphism in Wurtzite Materials

Demiroğlu

Bromley

2013

Phys. Rev. Lett.

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We generate a wide range of hexagonal sheet-based ZnO polymorphs inspired by enumeration of their characteristic underlying nets. Evaluating the bulk and nanofilm stabilities of these structures with ab initio calculations allows for an unprecedented overview of (nano)polymorphism in wurtzite materials. We find a rich low energy nanofilm polymorphism with a totally distinct stability ordering to that in the bulk. From this general basis we provide new insights into structural transitions observed during epitaxial growth and predictions for nanofilm stability with varying strain or thickness.

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Reversible Wurtzite–Tetragonal Reconstruction in ZnO(10$\bar 1$0) Surfaces

Cited by 42 publications

References 36 publications

In situ atomic-scale observation of oxidation and decomposition processes in nanocrystalline alloys

In situ atomic-scale observation of oxidation and decomposition processes in nanocrystalline alloys

Remarkable and Crystal‐Structure‐Dependent Piezoelectric and Piezoresistive Effects of InAs Nanowires

Nanofilm versus Bulk Polymorphism in Wurtzite Materials

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