Ultra‐broadband Polarisers Based on Metastable Free‐Standing Aligned Carbon Nanotube Membranes

Cole, Matthew T.; Doherty, Matthew; Parmee, Richard; Dawson, Paul; Milne, W. I.

doi:10.1002/adom.201400238

Cited by 13 publications

(9 citation statements)

References 59 publications

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“…Herman's Orientation Factor Calculation : HOF, f , has been used to assess the orientation of fiber and nanotube . Here, we use f value to evaluate the orientation of the CNTs, which was calculated from the standard formulation as defined by

f = \frac{1}{2} (3 〈 \cos^{2} ϕ 〉 - 1)

〈 \cos^{2} ϕ 〉 = \frac{\int_{normal0}^{\frac{π}{2}} I false(ϕ false) \cos^{2} ϕ \sin ϕ normal normald ϕ}{\int_{normal0}^{\frac{π}{2}} I false(ϕ false) \sin^{2} ϕ normal normald ϕ}

where

ϕ

is the azimuthal angle between the structural unit vector and the reference dircetion.…”

Section: Methodsmentioning

confidence: 99%

Biomimetic Carbon Nanotube Films with Gradient Structure and Locally Tunable Mechanical Property

Lin

Gui

Zeng

et al. 2015

Adv Funct Materials

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Naturally existing materials often acquire unique functions by adopting a gradient structure with gradual change in their microstructure and related properties. Imparting such an elegant structural control into synthetic materials has been a grand challenge in the field. Here, the concept of gradient structure into macroscopic carbon nanotube (CNT) films is employed and the CNT arrangement from well‐aligned array to completely random distribution, in a continuous and smooth way, is changed. Gradient films with tailored aligned‐to‐random transition rate or multilevel hierarchical structures with repeated transition have been fabricated. Local deformation and mechanical properties are directly related to the arrangement of CNTs and can be tailored by Herman's orientation factor; in particular, the elastic modulus and stiffness span over several orders of magnitude from aligned to random regions within a single monolithic film. Controlled synthesis of macroscopic CNT gradient structures with tunable mechanical properties opens a potential route toward manufacturing biomimetic functional materials with locally optimized design.

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f = \frac{1}{2} (3 〈 \cos^{2} ϕ 〉 - 1)

〈 \cos^{2} ϕ 〉 = \frac{\int_{normal0}^{\frac{π}{2}} I false(ϕ false) \cos^{2} ϕ \sin ϕ normal normald ϕ}{\int_{normal0}^{\frac{π}{2}} I false(ϕ false) \sin^{2} ϕ normal normald ϕ}

where

ϕ

is the azimuthal angle between the structural unit vector and the reference dircetion.…”

Section: Methodsmentioning

confidence: 99%

Biomimetic Carbon Nanotube Films with Gradient Structure and Locally Tunable Mechanical Property

Lin

Gui

Zeng

et al. 2015

Adv Funct Materials

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“…Elsewhere it has been widely used as a means of depositing phosphor materials. It has also been applied to the deposition of bundles of SWCNTs on various substrates, such as stainless steel or doped Si [167][168][169][170][171][172][173][174][175][176][177][178][179]. Composite CNT films deposited by electrophoresis have been fabricated with controlled surface density with good field emission performance, current density and long-term stability under high operating voltages, which has been applied to an electron source for high-resolution X-ray imaging [160].…”

Section: Electrophoresismentioning

confidence: 99%

“…CNTs experience high inter-tube van der Waals forces; they tend to agglomerate. Though this interaction has been exploited elsewhere to fabricate novel aligned nanostructured membranes [172], such agglomeration is problematic in producing homogenous CNT inks and solutions. As such, various, often sodium-based, surfactants such as sodium dodecylbenzene sulphate, sodium dodecyl sulphate, and Triton X are required to produce homogenous solutions with the CNTs well-dispersed throughout the solution.…”

Section: Vacuum Filtration and Screen Printingmentioning

confidence: 99%

“…Careful design of the cathode and supporting electrostatic lenses will minimise the size of the focal spot [228,229]. Additionally, further electrostatic rings or focussing coils may also be employed to redirect the flow of electrons emanating from the cathode, to further reduce the spot size, where the focal spot size is determined by measuring the Point Spread Function using standard methods [230].…”

Section: Micro Focal Sourcesmentioning

confidence: 99%

“…Soon thereafter this lead to the analysis of the diagnostic capabilities and therapeutic benefits of this new technology [5]. The increasing importance of X-ray techniques was evident with the development of X-ray diffraction methods [6][7][8] which lead ultimately to evidence the structure of DNA [9]. Compton back-scattering and fluorescence provided yet another raft of valuable applications [10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

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X-ray generation using carbon nanotubes

et al. 2015

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Since the discovery of X-rays over a century ago the techniques applied to the engineering of X-ray sources have remained relatively unchanged. From the inception of thermionic electron sources, which, due to simplicity of fabrication, remain central to almost all X-ray applications, there have been few fundamental technological advances. However, with the emergence of ever more demanding medical and inspection techniques, including computed tomography and tomosynthesis, security inspection, high throughput manufacturing and radiotherapy, has resulted in a considerable level of interest in the development of new fabrication methods. The use of conventional thermionic sources is limited by their slow temporal response and large physical size. In response, field electron emission has emerged as a promising alternative means of deriving a highly controllable electron beam of a well-defined distribution. When coupled to the burgeoning field of nanomaterials, and in particular, carbon nanotubes, such systems present a unique technological opportunity. This review provides a summary of the current state-of-the-art in carbon nanotube-based field emission X-ray sources. We detail the various fabrication techniques and functional advantages associated with their use, including the ability to produce ever smaller electron beam assembles, shaped cathodes, enhanced temporal stability and emergent fast-switching pulsed sources. We conclude with an overview of some of the commercial progress made towards the realisation of an innovative and disruptive technology.

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