Analysis on Crystal Structure of 7Å-Halloysite

Zhang, Hua Li; Lei, Xiaoning; Yan, Cheng; Wang, Hong Quan; Xiao, Guo; Jia, Hao; Wang, Duo; Qiu, Xiu Mei

doi:10.4028/www.scientific.net/amr.415-417.2206

Cited by 7 publications

(7 citation statements)

References 4 publications

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“…[32] The r 0 value is important, but it is not the only factor that governs the scrolling process. To understand that it is sufficient to look at the morphology of Mg 3 Si 2 O 5 (OH) 4 and Ni 3 Si 2 O 5 (OH) 4 nanoscrolls: they never form single-walled nanotubes of 18 and 30 nm in diameter except very initial stages of growth. [3,49] On the contrary, they are multi-walled.…”

Section: Energy Effect Of Cation Redistributionmentioning

confidence: 99%

“…Co-precipitation reaction in presence of amorphous SiO 2 yields poorly crystalline phase with layered structure. Its hydrothermal treatment leads to formation of a phase with a set of reflections corresponding to those of #10-381 Mg 3 Si 2 O 5 (OH) 4 or #49-1859 Ni 3 Si 2 O 5 (OH) 4 . An isostructural compound which would include both Mg 2 + and Ni 2 + ions is absent in the database.…”

Section: Energy Effect Of Cation Redistributionmentioning

confidence: 99%

“…Some of 1 : 1 phyllosilicates and clays possess a very intriguing feature, which consists in spontaneous curling of crystalline layer with a formation of nanotubes and nanoscrolls. Three of the most known representatives are chrysotile Mg 3 Si 2 O 5 (OH) 4 , [1][2][3] halloysite Al 2 Si 2 O 5 (OH) 4 , [4][5][6] and imogolite Al 2 SiO 3 (OH) 4 . [7,8] Because of wide occurrence in nature, their tubular shape had been revealed decades before the carbon [9][10] and chalcogenide [11,12] nanotubes discoveries.…”

Section: Introductionmentioning

confidence: 99%

“…Krasilin et al have demonstrated [41] that Mg/Ni ratio changes in correlation with the number of layers (outer diameter) of the nanoscroll. Here we attempt to deepen the study of chemical composition of individual (Mg,Ni) 3 Si 2 O 5 (OH) 4 multi-walled nanoscrolls using transmission electron microscopy in order to reveal a consistency in cations distribution along the phyllosilicate layer.…”

Section: Introductionmentioning

confidence: 99%

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Cation Redistribution along the Spiral of Ni‐Doped Phyllosilicate Nanoscrolls: Energy Modelling and STEM/EDS Study

et al. 2019

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Here, we study the stress‐induced self‐organization of Mg2+ and Ni2+ cations in the crystal structure of multiwalled (Mg1–x,Nix)3Si2O5(OH)4 phyllosilicate nanoscrolls. The phyllosilicate layer strives to compensate size and surface energy difference between the metal oxide and silica sheets by curling. But as soon as the layer grows, the scrolling mechanism becomes a spent force. An energy model proposes secondary compensation of strain: two cations distribute along the nanoscroll spiral in accordance with preferable radii of curvature. To reveal this, we study synthetic (Mg1–x,Nix)3Si2O5(OH)4 nanoscrolls by the scanning transmission electron microscopy/energy‐dispersive X‐ray spectroscopy (STEM/EDS) technique. For a number of scrolls, we have found indeed a change of Ni concentration with increase in distance from the nanoscroll central axis. The concentration gradient, according to our estimates, can reach 50 at.% over 25 nm of the wall thickness.

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Section: Energy Effect Of Cation Redistributionmentioning

confidence: 99%

Section: Energy Effect Of Cation Redistributionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Cation Redistribution along the Spiral of Ni‐Doped Phyllosilicate Nanoscrolls: Energy Modelling and STEM/EDS Study

et al. 2019

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“…Despite the initial observation of a spiral structure, more recent analyses of the crystal structure of halloysite have ignored the spiral configuration (Zhang et al, 2012). The present author has derived relationships for various deformities in crystal structure, deriving the Fourier transform for these forms in terms of spirals with varying radii (Mitra, 2012).…”

Section: Introductionmentioning

confidence: 98%

Spiral Structure of 7 Å Halloysite: Mathematical Models

Mitra

2013

Clays and clay miner.

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Halloysite is used for targeted delivery of drugs and other biomolecules. Renewed interest in examination by X-ray diffraction (XRD) to predict the size of particles that can be loaded onto the nanotubes has resulted. Anhydrous halloysite consists of spiraled tubules the length and diameter of which can be determined by measurement using an electron microscope. In spite of ample evidence regarding the spiral structure of halloysite, current programs to evaluate the structure of halloysite nanotubes consider it to be a hollow tube or a cylinder which prevents accurate prediction of its structure and leads to misinformation about the sizes of materials that can be loaded onto the nanotubes. The overall objective of the current study was to derive equations to estimate the structure of halloysite nanotubes which take into consideration its spiral structure. The study of Fourier transform either by electron diffraction or XRD led to the measurement of the spiral thickness and the nature of the spiral. Calculations of the nanotube dimensions may determine the ability of these carriers to allow the mechanical delivery of certain drugs.Here the structure of hydrated halloysite (hollow cylindrical tubes with a doughnut-like cross-section) and anhydrous halloysite (spiraled or helical structure) are described as previously reported in the literature. The Fourier transform of the spiraled structure was selected based on three different kinds of spirals: the Archimedean spiral, the Power spiral, and the Logarithmic spiral. Programs used to define the crystal structure of materials and to calculate the Fourier transform need to take the spiral structure into consideration.

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Energy Modeling of Competition Between Tubular and Platy Morphologies of Chrysotile and Halloysite Layers

Krasilin

2020

Clays and clay miner.

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The present study considered the problem of halloysite nanoscroll synthesis by energy modeling of the formation of chrysotile and halloysite particles. The main aim of the study was to reveal an energy preference between scrolled and platy morphologies of the particles. Both hydrosilicates possess the ability to scroll spontaneously but relatively facile hydrothermal synthesis of the nanoscrolls is available only to the former, whereas halloysite forms mainly plates under the same conditions. This issue was investigated by a phenomenological energy model, taking into account: (1) strain energy due to the size difference between metal oxide and silica sheets; (2) surface-energy difference on the opposite sides of the layer; and (3) adhesion energy. Calculations showed that the halloysite layer had a significant scrolling potential due to the first energy component, but the surface-energy difference acted in the opposite direction and tried to unbend the layer. In contrast, these two actions were co-directional in chrysotile layers. In both cases, the formation of multi-layered plates became more energy favorable when the specific surface energy of the edges decreased. In the range 0.5–3 J/m2 for the specific surface energy, only halloysite layers showed an energy preference for platy particles over nanoscrolls, especially at small layer sizes. Certain processes, such as hydration, could reduce the corresponding specific surface energy value and, as a result, could stabilize the platy morphology of halloysite at the earliest stages of particle growth under hydrothermal conditions.

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Analysis on Crystal Structure of 7Å-Halloysite

Cited by 7 publications

References 4 publications

Cation Redistribution along the Spiral of Ni‐Doped Phyllosilicate Nanoscrolls: Energy Modelling and STEM/EDS Study

Cation Redistribution along the Spiral of Ni‐Doped Phyllosilicate Nanoscrolls: Energy Modelling and STEM/EDS Study

Spiral Structure of 7 Å Halloysite: Mathematical Models

Energy Modeling of Competition Between Tubular and Platy Morphologies of Chrysotile and Halloysite Layers

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