Directly Rolling Nanosheets into Nanotubes.

Ma, Renzhi; Bandô, Yoshio; Sasaki, Takayoshi

doi:10.1002/chin.200418241

Cited by 3 publications

(4 citation statements)

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“…It may be amourphous particles initially which then transform into network structures linked by hydrogen bonds and forms nanosheets or sheets of crumpled nanostructures. The nanosheets could rolled up and be transformed into hollow tubular structures or nanofibers [17,31], which may or may not be crystalline. The initial spherical particles of boehmite are sol solution with low viscosity.…”

Section: Hydrothermal and Sol Gel Processesmentioning

confidence: 99%

“…[54] However, whatever the starting materials used in the synthesis, the nanofibrous boehmite intermediate will have to be formed [22] for the formation of the nanofibers as mentioned above. The starting Al precursor is first hydrolyzed with water to form the hydroxide [17,22,32,37,38], aged to the viscous gel fibers of hydrated AlOOH, which can be calcined directly or electrospun or drawn from the viscous gel and converted to ceramic fibers after firing [16,27,[31][32][33][34][35][36][37]. The metallic aluminum powder used for the process is prepared by exploding the metal wire by a high density current pulse normally produced by discharging a capacitor bank.…”

Section: Hydrothermal and Sol Gel Processesmentioning

confidence: 99%

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Synthesis of Alumina Nanofibers and Composites

Noordin¹,

Liew²

2010

Nanofibers

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IntroductionAlumina, Al 2 O 3 , is a ceramic metal oxide of great importance as building material, refractory material, electrical and heat insulator, attributed to its high strength, corrosion resistance, chemical stability, low thermal conductivity, and good electrical insulation. One phase of alumina, the -phase is widely used as catalyst, catalyst support and adsorbent because its high porosity and surface area. It is conventionally prepared by heating the hydrated trihydroxides, gibbsite and bayerite, to temperature of > 1000 o C to obtain the -alumina, corundum, a material with great hardness and low surface area. The trihydroxides, gibbsite, bayerite, both are Al(OH) 3. nH 2 O and the monohydroxyl oxide, boehmite, AlO(OH)·αH 2 O, have the monoclinic crystal structure with similar lattice parameters (a=0.866 nm, b=0.506 nm, c=0.983 nm, =94°34′ in boehmite, a=0.868 nm, b=0.507 nm, c=0.972 nm, =94°34′ in gibbsite, and a=0.867 nm, b=0.506 nm, c=0.942 nm, =90°26′ in bayerite [1,2]. In the process of heat treatment, the trihydroxide undergoes a series of transformations. It loses the water of hydration, then dehydroxalate at < 300 o C to form the monohydroxyl oxide boehmite, AlO(OH), which on further heating to increasingly higher temperatures, changes to the transition aluminas, including the -, -, -, and -phases, which then transform finally to the -form. These transition aluminas are crystalline solids with high porosity and surface areas as well as acidic and basic properties, which make them suitable as adsorbents, catalyst, catalyst support and fabricated into filtration membranes as well as used as fillers or components in polymer/ inorganic composite materials with enhanced mechanical properties. The conventional alumina as obtained are usually powder of particulates. These could be fabricated into alumina fibers by various method, through melt growth techniques including the internal crystallization method and extrusion, electrospraying [3] and electrospinning [4][5][6][7][8] have been developed for producing Al 2 O 3 fibers. The high surface areas of transition aluminas are due to the presence of pores. These pores are irregular in sizes and size distributions, and are mainly micropores of diameter less than 2 nm. Since the synthesis of mesoporous materials was first reported in the late 1980s , a number of methods for the synthesis of mesoporous alumina have been reported [8,9]. More recently, interest in nano-materials and nanotechnology has spurred a fury of investigations

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Section: Hydrothermal and Sol Gel Processesmentioning

confidence: 99%

Section: Hydrothermal and Sol Gel Processesmentioning

confidence: 99%

Synthesis of Alumina Nanofibers and Composites

Noordin¹,

Liew²

2010

Nanofibers

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“…It is widely known that the electronic and optical performances of such 2D crystals are extremely sensitive to flexion deformation [4][5][6][7][8][9]. For example, graphene is regarded as the strongest material in the world with a Young's modulus of 1 terapascal [10], and the Young's modulus of monolayered MoS 2 is comparable to that of steel [11], but they are extremely easy to bend and ripple and can even be directly rolled into nanotubes [12]. Most recently, an interesting bending Poisson effect was revealed in a series of 2D crystals where the bending deformation is found to be able to induce deformations along the bending moment [13].…”

Section: Introductionmentioning

confidence: 99%

Bending-induced extension in two-dimensional crystals

Pan¹,

Yao²,

Wang³

et al. 2016

Acta Mech. Sin.

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We find by ab initio simulations that significant overall tensile strain can be induced by pure bending in a wide range of two-dimensional crystals perpendicular to the bending moment, just like an accordion being bent to open. This bending-induced tensile strain increases in a power law with bent curvature and can be over 20% in monolayered black phosphorus and transition metal dichalcogenides at a moderate curvature of 2 nm −1 but more than an order weaker in graphene and hexagon boron nitride. This accordion effect is found to be a quantum mechanical effect raised by the asymmetric response of chemical bonds and electron density to the bending curvature.Keywords Monolayer black phosphorus · Bending to extension · Accordion effect · Density functional theory Douxing Pan and Yao Li have contributed equally to this work. Electronic supplementary materialThe online version of this article

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“…Although these techniques have not been used extensively, interesting results have been obtained. EELS studies have assigned titania nanotube phase to anatase and rutile [10,19], and have shown that the nanotubes contain no residual Na + [20]. IR studies have indicated that -OH and water is present in the samples [16,18,21,22].…”

Section: Introductionmentioning

confidence: 99%

Relationship of Titania Nanotube Binding Energies and Raman Spectra

Morgan

Waclawik

Frost

2006

2006 International Conference on Nanoscience and Nanotechnology

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Abstract-Novel nanostructured titania nanotubes and hydrogen titanate nanoribbons were synthesised using hydrothermal treatment of Degussa P25. The nanostructure types formed were monitored as a function of the hydrothermal conditions. Changes in structure was evaluated using X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Raman spectroscopy.X-ray photoelectron spectroscopy (XPS) of Ti(2p 3/2 ) and O(1s) binding energies in titania nanotubes were measured and a systematic trend in the XPS binding energies was observed. This indicated a strengthening of the Ti-O bond occurred as the material phase changed from titania nanotube to the titanate ribbon form. The changes in binding energies for both the Ti and O XPS peaks were consistent with changes observed in the Raman spectra of nanostructured titania.

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Directly Rolling Nanosheets into Nanotubes.

Cited by 3 publications

References 1 publication

Synthesis of Alumina Nanofibers and Composites

Synthesis of Alumina Nanofibers and Composites

Bending-induced extension in two-dimensional crystals

Relationship of Titania Nanotube Binding Energies and Raman Spectra

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