The structure of halloysite

Mitra, G. B.; Bhattacherjee, S.

doi:10.1107/s0567740875009041

Cited by 32 publications

(24 citation statements)

References 9 publications

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“…Halloysite is a polytype of kaolinite (Al 2 (OH) 4 [Si 2 O 5 ]) and differs mainly in the morphology of the crystals, which are curved or rolled (1)(2)(3)(4)(5)(6)(7). Halloysite consists of a layer structure composed of siloxane and gibbsite-like layers.…”

Section: Introductionmentioning

confidence: 99%

Rehydration and Phase Changes of Potassium Acetate-Intercalated Halloysite at 298 K

Frost

Kristóf

Horvath

et al. 2000

Journal of Colloid and Interface Science

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Section: Introductionmentioning

confidence: 99%

Rehydration and Phase Changes of Potassium Acetate-Intercalated Halloysite at 298 K

Frost

Kristóf

Horvath

et al. 2000

Journal of Colloid and Interface Science

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“…It was concluded that metahalloysite had a lath-like cylindrival structure and the kaolin layers were considered to be arranged parallel to one another but shifted parallel to themselves [16]. Although the values of the lattice parameters were satisfactory, recent identifications of the secondary structures have rendered necessary the development of a theory which would explain not only perfect cylinders or coaxial cylinders but also helical and spiral structures.…”

Section: Discussionmentioning

confidence: 99%

“…In 1975, we had attempted to explain the structure of halloysite [16] in the light of a theory of diffraction by curved crystals developed by us [25][26][27]. It was concluded that metahalloysite had a lath-like cylindrival structure and the kaolin layers were considered to be arranged parallel to one another but shifted parallel to themselves [16].…”

Section: Discussionmentioning

confidence: 99%

“…The various forms assumed by nanotubes include isolated cones [12], disordered aggregates of cones [10], multilayered cones with different apex angles [14,15], as well as stacked closed cones, also called stacked lampshades. Among naturally occurring minerals, Halloysite [16], Cylindrite [17], tochilinites [18] etc form cylindrical morphology. The cylindrical morphology of terrestrial Tectialinite has been described by Jambor [19] as resembling a rolled up newspaper.…”

Section: Introductionmentioning

confidence: 99%

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Fourier Transforms of Tubular Objects with Spiral Structures

Mitra¹

2012

JCPT

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Crystal structures of several naturally occurring minerals are known to contain various deformities such as cones, cylinders, and tapered hollow cylinders with different apex angles, which have been described as solid and hollow cones, "cups", "lampshades" as well as rolled cylindrical planes. The present study was undertaken to determine how these different shapes within a crystal structure can be explained. Since the usual method of observing them is by either X-ray and electron diffraction or electron microscopy, we investigated Fourier transforms of these forms, which were considered in terms of spirals with varying radii. Three types of spirals were considered, namely: 1) Archimedean spiral; 2) Involute of a circle or power spiral and 3) Logarithmic spiral. Spiraling caused the radius r to be modified by a factor f(θ), so that r becomes rf(θ), where f(θ) = θ for Archimedean helix, θ n for power helices like θ 1/2 for Fermat's helix, θfor hyperbolic helix and e θ or e -θ for logarithmic helix, r and θ being co-ordinates of the map on which the helix has to be drawn, f(θ) is unaffected by the magnitude of r. Expressions have been derived that explain the diffraction of structures containing the distortions described above, and bring all of these phenomena under one "umbrella" of a comprehensive theory.

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“…For the calculation of microstrain, the line profiles were subjected to variance analysis. 14 An aggregate of distorted crystallites as a measure of the crystallite size and strain could affect the variance of the X-ray diffraction line profiles. Since the method is sensitive to the variation near the tails of the peaks, a careful adjustment of the background was carried out following the method of Mitra and Misra.…”

Section: Structural Studiesmentioning

confidence: 99%

Role of Solution pH on the Microstructural Properties of Spin Coated Cobalt Oxide Thin Films

Valanarasu¹,

Dhanasekaran²,

Karunakaran³

et al. 2014

j. nanosci. nanotech.

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Cobalt Oxide (Co3o4) thin films have been successfully coated onto glass substrates at various solution pH by sol-gel spin coating technique. The film thickness was estimated using weight gain method and it revealed that the film thickness increased with solution pH values. The prepared film structural, morphological, optical and electrical properties were studied using X-ray diffraction (XRD), scanning electron microscope (SEM), UV-Vis-NIR spectrophotometer and Vander Pau method, respectively. The structure of the films were found to be face centered cubic with preferential orientation along (311) plane. X-ray line profile analysis was used to evaluate the micro structural parameters such as crystallite size, micro strain, dislocation density and stacking fault probability. The crystallite size values are increased with increase of solution pH values and maximum value of crystallite is estimated at 40.8 nm at solution pH 8 +/- 0.1. Morphological results showed that the pH of the solution has a marked effect on morphology of the Co3O4 thin films. The optical studies revealed that the band gap can be tailored between 2.16 to 2.31 eV by altering pH. The thin film formed at a solution pH 7 is found to have a low resistivity and high mobility. The electrical resistivity (p), carrier concentration (n) and mobility (micro) values are 0.1 x 10(3) omega x cm, 8.9 cm2 gammas(-1) and 6.6 x 10(14) cm(-3), respectively for Co3O4 thin film prepared at solution pH 7 +/- 0.1. EDAX studies showed that the cobalt content increased and the oxygen content decreased with increase of pH.

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The structure of halloysite

Cited by 32 publications

References 9 publications

Rehydration and Phase Changes of Potassium Acetate-Intercalated Halloysite at 298 K

Rehydration and Phase Changes of Potassium Acetate-Intercalated Halloysite at 298 K

Fourier Transforms of Tubular Objects with Spiral Structures

Role of Solution pH on the Microstructural Properties of Spin Coated Cobalt Oxide Thin Films

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