Quasi-one-dimensional metal oxide materials—Synthesis, properties and applications

Lu, Jia Grace; Chang, Pai‐Chun; Fan, Zhiyong

doi:10.1016/j.mser.2006.04.002

Cited by 557 publications

(280 citation statements)

References 249 publications

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“…In the framework of a vapor− solid (VS) mechanism, the first condensed oxide molecules serve as nucleation sites in a self-catalytic scheme,where further deposition takes place leading to the formation of nanowires if there is a preferred growth direction. 30 In such a case, the minimization of free energy determines the directional growth during the condensation process, which is dominated by the surface energy growth of nanowires. This can be of crucial importance when it comes to anisotropic materials, as it is the case of the monoclinic β-Ga 2 O 3 along the b direction.…”

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confidence: 99%

Shape Engineering Driven by Selective Growth of SnO₂ on Doped Ga₂O₃ Nanowires

et al. 2016

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Tailoring the shape of complex nanostructures requires control of the growth process. In this work, we report on the selective growth of nanostructured tin oxide on gallium oxide nanowires leading to the formation of SnO 2 /Ga 2 O 3 complex nanostructures. nanowires grow preferentially. High-resolution transmission electron microscopy analysis reveals epitaxial relationship lattice matching between the Ga 2 O 3 axis and SnO 2 particles, forming skewer-like structures. The addition of chromium oxide to the source materials modifies the growth direction of the trunk Ga 2 O 3 nanowires, growing along the [001], with crossing SnO 2 wires. The SnO 2 /Ga 2 O 3 junctions does not meet the lattice matching condition, forming a grain boundary. The electronic and optical properties have been studied by XPS and CL with high spatial resolution, enabling us to get both local chemical and electronic information on the surface in both type of structures. The results will allow tuning optical and electronic properties of oxide complex nanostructures locally as a function of the orientation. In particular, we report a dependence of the visible CL emission of SnO 2 on its particular shape. Orange emission dominates in SnO 2 /Ga 2 O 3 crossing wires while green-blue emission is observed in SnO 2 particles attached to Ga 2 O 3 trunks. The results show that the Ga 2 O 3 −SnO 2 system appears to be a benchmark for shape engineering to get architectures involving nanowires via the control of the growth direction of the nanowires. KEYWORDS: Complex oxide nanowires, selective growth, crossed nanowires, transmission electron microsopy, cathodoluminescence A dvances in smart nanostructured materials require a deep understanding of the growth mechanisms to develop novel designs and architectures. Engineering new architectures will enable the combination of zero-, one-and two-dimensional systems enhancing the functionalities in comparison with their single counterparts (quantum dots, nanowires, or nanosheets). 1 Some physical properties, such as optical and transport properties, could be strongly dependent on the morphology of nanomaterials, hence nanomaterials with mixed dimensionality could offer extra applications. For example, light emission in nanowires may be affected if nanowires are assembled with quantum dots in the same nanostructure. 2 Beside dimensionality, we can even broaden out the tailoring capabilities of nanostructured materials by mixing several chemical elements or compounds. For instance, 1D-TiO 2 /2D-ZnIn 2 S 4 nanostructures with improved photocatalytic properties have been very recently reported. 3 Semiconducting oxides are an attractive family of smart materials with wide range of morphologies within the quasi-one dimension (nanowires, nanobelts, or nanorods). 4 Besides, these oxides offer a high versatility in the following applications: optical and mechanical resonators, lasing, sensors, photocatalysis, solar cells, and biomedical and healthcare usages to name a few. 5−8 A great deal of research has been...

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Shape Engineering Driven by Selective Growth of SnO₂ on Doped Ga₂O₃ Nanowires

et al. 2016

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“…The fabrication techniques of homogeneous 1-D nanostructures have pursued the control over shape, aspect ratio, and crystalline arrangement to a considerable degree [8][9][10], and the improvement of the synthesis methods [11][12][13] has recently achieved the direct integration of functional nanostructures into nanodevices [14][15][16].…”

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Bottom-up growth of fully transparent contact layers of indium tin oxide nanowires for light-emitting devices

et al. 2009

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Thin layers of indium tin oxide are widely used as transparent coatings and electrodes in solar energy cells, flat-panel displays, antireflection coatings, radiation protection and lithium-ion battery materials, because they have the characteristics of low resistivity, strong absorption at ultraviolet wavelengths, high transmission in the visible, high reflectivity in the far-infrared and strong attenuation in the microwave region. However, there is often a trade-off between electrical conductivity and transparency at visible wavelengths for indium tin oxide and other transparent conducting oxides. Here, we report the growth of layers of indium tin oxide nanowires that show optimum electronic and photonic properties and demonstrate their use as fully transparent top contacts in the visible to near-infrared region for light-emitting devices

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“…[167][168][169][170][171] However, because the Coulomb potential diverges in one-dimension, and a soft-Coulomb potential shall be used instead, [172][173][174][175] the real physical meaning of this density scaling is rather ambiguous. For this reason, it has never been considered in meta-GGA development; despite it is a possible constraint at this level.…”

Section: Two-dimensional Density Scalingmentioning

confidence: 99%

Kinetic‐energy‐density dependent semilocal exchange‐correlation functionals

Sala

Fabiano

Constantin

2016

Int J of Quantum Chemistry

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We present the theory of semilocal exchange-correlation (XC) energy functionals which depend on the Kohn-Sham kinetic energy density (KED), including the relevant class of meta-generalized gradient approximation (meta-GGA) functionals. Thanks to the KED ingredient, meta-GGA functionals can satisfy different exact constraints for XC energy and can be made one-electron selfcorrelation free. This leads to a better accuracy over a wider range of properties with respect to GGAs, often reaching the accuracy of hybrid functionals, but at much reduced computational cost.An extensive survey of the relevant literature on existing KED dependent XC functionals is provided, considering nonempirical, semi-empirical, and fully empirical ones. A deeper analysis and a wide benchmark are presented for functionals derived considering only exact constraints and parameters obtained from model and/or atomic systems. K E Y W O R D Sdensity functional theory, kinetic energy, meta-GGA | I N T R O D U C T I O NKohn-Sham (KS)-density functional theory (DFT) [1][2][3][4][5] is nowadays one of the most popular computational approaches in quantum chemistry, solid-state physics, and materials science. [6][7][8][9][10][11] While the ground-state description of a real system of interacting electrons requires a complicate N-electron wavefunction, in KS-DFT this is mapped onto an auxiliary system of noninteracting electrons having the same ground-state density, which can be easily described using N single-particle KS orbitals. [1,2] The correspondence between the many-electron problem and the KS system is in principle exact [1,3] and it is based on the so called exchange-correlation (XC) energy functional, which collects all the quantum electron-electron interaction terms beyond the Hartree one. [12] Within the constrained-search formalism, [13] the XC energy functional is:E xc ½q 5 min W!q hWjT 1V ee jWi2T s ½q 2J½q 5E x ½q 1U c ½q 1T c ½q ;(1) where W is an N-electron ground-state wavefunction yielding the electron density q,T is the kinetic energy (KE) operator,V ee is the electron-electron interaction operator, T s is the KE of the noninteracting system, J is the Coulomb energy, E x is the exact exchange energy, and U c and T c represent, respectively, the potential and the kinetic contributions to the DFT correlation energy E c 5U c 1T c . The important point of Equation1 is that it is an universal functional of the electron density. However, its explicit functional form is not known, and any practical realization of KS-DFT is based on an approximated XC functional. The latter determines in practice the overall accuracy of the KS-DFT calculation.The study of the exact properties of the XC energy functional as well as the development of new and improved approximations have been hot research topics in DFT for more than three decades, and a large number of XC approximations has been proposed. [12,14,15] The different XC functionals are usually classified, according to their complexity, on the so called Jacob's ladder of DFT [14,16] whic...

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Quasi-one-dimensional metal oxide materials—Synthesis, properties and applications

Cited by 557 publications

References 249 publications

Shape Engineering Driven by Selective Growth of SnO₂ on Doped Ga₂O₃ Nanowires

Shape Engineering Driven by Selective Growth of SnO₂ on Doped Ga₂O₃ Nanowires

Bottom-up growth of fully transparent contact layers of indium tin oxide nanowires for light-emitting devices

Kinetic‐energy‐density dependent semilocal exchange‐correlation functionals

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Quasi-one-dimensional metal oxide materials—Synthesis, properties and applications

Cited by 557 publications

References 249 publications

Shape Engineering Driven by Selective Growth of SnO2 on Doped Ga2O3 Nanowires

Shape Engineering Driven by Selective Growth of SnO2 on Doped Ga2O3 Nanowires

Bottom-up growth of fully transparent contact layers of indium tin oxide nanowires for light-emitting devices

Kinetic‐energy‐density dependent semilocal exchange‐correlation functionals

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Shape Engineering Driven by Selective Growth of SnO₂ on Doped Ga₂O₃ Nanowires

Shape Engineering Driven by Selective Growth of SnO₂ on Doped Ga₂O₃ Nanowires