Direct oxygen imaging in titania nanocrystals

Lü, Weigang; Bruner, Britain; Casillas, Gilberto; Mejía-Rosales, Sergio; Farmer, Patrick J.; José–Yacamán, Miguel

doi:10.1088/0957-4484/23/33/335706

Cited by 5 publications

(2 citation statements)

References 48 publications

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“…It can be concluded that simulated data are in a good agreement with experimental ones and it is obvious that Hf atoms are incorporated into the lattice in the position of titanium atoms. In this study, we did not aim to visualize the oxygen atoms in anatase TiO 2 structure, as it was previously reported [ 31 ]. Moreover, in the case of the nanoparticles, it is rather difficult to obtain exactly the predetermined zone axis, and also the weak scattering intensity of oxygen atoms makes them invisible in the presented micrographs.…”

Section: Resultsmentioning

confidence: 99%

Effect of Hf-doping on electrochemical performance of anatase TiO ₂ as an anode material for lithium storage

et al. 2018

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Hafnium-doped titania (Hf/Ti = 0.01; 0.03; 0.05) had been facilely synthesized via a template sol–gel method on carbon fibre. Physico-chemical properties of the as-synthesized materials were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, scanning transmission electron microscopy, X-ray photoelectron spectroscopy, thermogravimetry analysis and Brunauer–Emmett–Teller measurements. It was confirmed that Hf4+ substitute in the Ti4+ sites, forming Ti1–xHfxO2 (x = 0.01; 0.03; 0.05) solid solutions with an anatase crystal structure. The Ti1–xHfxO2 materials are hollow microtubes (length of 10–100 µm, outer diameter of 1–5 µm) composed of nanoparticles (average size of 15–20 nm) with a surface area of 80–90 m2 g–1 and pore volume of 0.294–0.372 cm3 g–1. The effect of Hf ion incorporation on the electrochemical behaviour of anatase TiO2 in the Li-ion battery anode was investigated by galvanostatic charge/discharge and electrochemical impedance spectroscopy. It was established that Ti0.95Hf0.05O2 shows significantly higher reversibility (154.2 mAh g–1) after 35-fold cycling at a C/10 rate in comparison with undoped titania (55.9 mAh g–1). The better performance offered by Hf4+ substitution of the Ti4+ into anatase TiO2 mainly results from a more open crystal structure, which has been achieved via the difference in ionic radius values of Ti4+ (0.604 Å) and Hf4+ (0.71 Å). The obtained results are in good accord with those for anatase TiO2 doped with Zr4+ (0.72 Å), published earlier. Furthermore, improved electrical conductivity of Hf-doped anatase TiO2 materials owing to charge redistribution in the lattice and enhanced interfacial lithium storage owing to increased surface area directly depending on the Hf/Ti atomic ratio have a beneficial effect on electrochemical properties.

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Section: Resultsmentioning

confidence: 99%

Effect of Hf-doping on electrochemical performance of anatase TiO ₂ as an anode material for lithium storage

et al. 2018

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“…Because of their natural abundance, (101) and (301) coherent twins in rutile have been the subject of previous study by high-resolution TEM; , furthermore, γ (101) GB and γ (301) GB have been calculated using nonreactive MD potentials . The lowest energy configuration for (101) twins consists of a pseudoreflection twin, a reflection twin coupled with a 1/2 [111] translation in the plane of the GB, resulting in reflection symmetry across the twin boundary only for the cation sublattice; in rutile, the (101) pseudoreflection twin is equivalent to a rotation twin around the [010] rotation axis.…”

Section: Resultsmentioning

confidence: 99%

Investigating Grain Boundary Structures and Energetics of Rutile with Reactive Molecular Dynamics

et al. 2016

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Determining quantitative grain boundary (GB) energies as a function of microscopic orientation parameters is essential in order to understand the population of boundaries present in polycrystalline ceramics and films, and the physical properties that result from these boundaries. Here, we investigate the use of two reactive potentials, COMB3 and ReaxFF, to predict free surface and grain boundary structures and energies in the TiO 2 rutile system, and compare these results against previously reported ab initio surface and interfacial energies. We demonstrate reactive MD potentials to be generally capable of reproducing key features anticipated for GB structures and energetics, including relative GB and surface energy, charge distributions and potential for different polar and nonpolar terminations, and energy cusps at low-energy interfaces (e.g., coherent twin boundaries, coherent site lattice boundaries). This work establishes the foundation for further use of reactive MD to simulate libraries of oxide GBs and dynamic processes occurring along those GBs.

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Twinning-mediated anomalous alignment of rutile films revealed by synchrotron X-ray nanodiffraction

Chiang

et al. 2021

iScience

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Summary Nanotwin structures in materials engender fascinating exotic properties. However, twinning usually alter the crystal orientation, resulting in random orientation and limited performances. Here, we report a well-aligned rutile TiO 2 nanotwin film with superior preferential orientation than its isostructural substrate. By means of the synchrotron X-ray Laue nanodiffraction technique, the crystal orientation, twin boundaries, and deviatoric stresses of the film were quantitatively imaged at unprecedented spatial resolution to unravel the underlying mechanism of this anomalous alignment. Massive {101}-type rutile nanotwins were observed, and a crystallographic relationship of the heteroepitaxy was proposed. The rapid twinning and twin-controlled heteroepitaxy are responsible for the texture improvement. This work would open up opportunities for rational design of better twin-based functional materials, and implies the powerful capabilities of X-ray nanodiffraction technique for multidisciplinary applications.

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Direct oxygen imaging in titania nanocrystals

Cited by 5 publications

References 48 publications

Effect of Hf-doping on electrochemical performance of anatase TiO ₂ as an anode material for lithium storage

Effect of Hf-doping on electrochemical performance of anatase TiO ₂ as an anode material for lithium storage

Investigating Grain Boundary Structures and Energetics of Rutile with Reactive Molecular Dynamics

Twinning-mediated anomalous alignment of rutile films revealed by synchrotron X-ray nanodiffraction

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Direct oxygen imaging in titania nanocrystals

Cited by 5 publications

References 48 publications

Effect of Hf-doping on electrochemical performance of anatase TiO 2 as an anode material for lithium storage

Effect of Hf-doping on electrochemical performance of anatase TiO 2 as an anode material for lithium storage

Investigating Grain Boundary Structures and Energetics of Rutile with Reactive Molecular Dynamics

Twinning-mediated anomalous alignment of rutile films revealed by synchrotron X-ray nanodiffraction

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Effect of Hf-doping on electrochemical performance of anatase TiO ₂ as an anode material for lithium storage

Effect of Hf-doping on electrochemical performance of anatase TiO ₂ as an anode material for lithium storage