The structure and growth of hollow conical single crystals of cadmium sulphide

Chandrasekharaiah, M. N.; Krishna, P.

doi:10.1016/0022-0248(69)90012-8

Cited by 17 publications

(5 citation statements)

References 9 publications

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“…There has been some attempt at explaining the emergence of this phenomenon. It has been suggested that the origin of a hollow feature is a dislocation in the crystal structure, with a spiral dislocation being responsible for a pyramidal hollow like those observed in the present study for salicylic acid crystals. , The that data from FEM simulations show that the characteristic patterns of diffusive mass transport also appear to play a role in the emergence, growth, and closure of hollow features.…”

Section: Resultssupporting

confidence: 70%

“…34 In the present study, hollow features in salicylic acid crystals were sometimes observed, and the mass transport simulations that are an integral part of our studies provide key insights into the conditions under which hollow features appear. Trapped bubbles which result may be a concern for producing crystalline drug forms, and studies such as those described herein could be used to set conditions under which these undesirable features could be avoided.…”

Section: Introductionmentioning

confidence: 58%

“…There is a fairly limited body of work on hollow crystals, 32,33 and the mechanism of their formation has not clearly been established, although it has been postulated that the presence of hollow features is due to dislocations. 34 In the present study, hollow features in salicylic acid crystals were sometimes observed, and the mass transport simulations that are an integral part of our studies provide key insights into the conditions under which hollow features appear. Trapped bubbles which result may be a concern for producing crystalline drug forms, and studies such as those described herein could be used to set conditions under which these undesirable features could be avoided.…”

Section: ■ Introductionmentioning

confidence: 58%

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Quantitative Plane-Resolved Crystal Growth and Dissolution Kinetics by Coupling In Situ Optical Microscopy and Diffusion Models: The Case of Salicylic Acid in Aqueous Solution

Perry

Peruffo

Unwin

2013

Crystal Growth & Design

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The growth and dissolution kinetics of salicylic acid crystals are investigated in situ by focusing on individual microscale crystals. From a combination of optical microscopy and finite element method (FEM) modeling, it was possible to obtain a detailed quantitative picture of dissolution and growth dynamics for individual crystal faces. The approach uses real-time in situ growth and dissolution data (crystal size and shape as a function of time) to parameterize a FEM model incorporating surface kinetics and bulk to surface diffusion, from which concentration distributions and fluxes are obtained directly. It was found that the (001) face showed strong mass transport (diffusion) controlled behavior with an average surface concentration close to the solubility value during growth and dissolution over a wide range of bulk saturation levels. The (110) and (110) (001) face compared to the center, and this flux has to be redistributed across the (001) surface. As the crystal grows, the redistribution process evidently can not be maintained so that the edges grow at the expense of the center, ultimately creating high index internal structures. At later times, we postulate that these high energy faces -starved of material from solution -dissolve and the extra flux of salicylic acid causes the voids to close.2

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Section: Resultssupporting

confidence: 70%

Section: Introductionmentioning

confidence: 58%

Section: ■ Introductionmentioning

confidence: 58%

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Quantitative Plane-Resolved Crystal Growth and Dissolution Kinetics by Coupling In Situ Optical Microscopy and Diffusion Models: The Case of Salicylic Acid in Aqueous Solution

Perry

Peruffo

Unwin

2013

Crystal Growth & Design

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“…Growth only in the interfacial zone combined with the competition for the interface between the crystals and surfactant is believed to be the key factor in the mechanism leading to the hollow-conical growth. Although a similar hollow-conical crystal morphology has been reported previously for cadmium sulfide crystals, 3,4 the conical crystals observed in the present study with dimensions ranging from 10 2 to 10 3 μm are unique in the hydrate crystallography literature to the best of our knowledge.…”

supporting

confidence: 88%

“…Our purpose is to report previously unreported hollow-conical crystals associated with the interfacial crystallization of a clathrate hydrate. The only other hollow conical crystals of which we are aware, of cadmium sulfide , for example, are much smaller and are formed from a gas phase.…”

mentioning

confidence: 99%

Surfactant Effects on Hydrate Crystallization at the Water–Oil Interface: Hollow-Conical Crystals

Karanjkar

Lee

Morris

2012

Crystal Growth & Design

127

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Clathrate hydrates are icelike crystalline compounds with small guest molecules trapped inside the cages of hydrogen bonded water molecules. Clathrate hydrate crystal growth is studied for the specific case of the guest molecule cyclopentane. Cyclopentane hydrate formation is visualized at a millimeter-scale water drop. Crystal formation takes place at the water–organic interface and has been shown in prior work to occur in a three-step sequence of nucleation, lateral surface growth, and radial growth. This study describes cyclopentane hydrate crystal characteristics during the lateral surface growth and demonstrates the effect of the oil-soluble surfactant sorbitan monooleate (Span 80) on the hydrate crystal growth. A faceted polycrystalline hydrate shell is formed around the water drop in the absence of surfactant. A unique hollow-conical crystal is observed at Span 80 concentrations greater than 0.01% by volume in cyclopentane; the critical micelle concentration is 0.03% Span 80. The conical crystals have a polygonal base, usually hexagonal, which is pinned at the water–cyclopentane interface; growth occurs at this base and drives the previously formed crystal into the water phase. Morphology is dependent upon the growth taking place at the interface where both components of hydrate (i.e., water and cyclopentane) are present at large concentration. The hollow-conical crystals grow to over 100 μm in linear dimensions in all directions. The morphology described is seen at a range of Span 80 and cyclopentane concentrations. A hypothesis is proposed to relate crowding of surfactant molecules at the interface to the observed hollow-conical crystal shape.

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Oberflächenstörungen und Hohlwachstum bei der Züchtung von β‐Kupferphthalocyanin‐Einkristallen aus der Gasphase

Hamann

Przyborowski

Kersten

1976

Cryst Res and Technol

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Bei der Züchtung von Kupferphthalocyanin‐Einkristallen aus der Gasphase bilden sich häufig Hohlformen. Diese Erscheinung erschwert bzw. verhindert vorgesehene experimentelle Studien. Untersuchungen zur Überwindung dieser Schwierigkeiten werden beschrieben. Ursachen des Hohlwachstums sind, wie aus den Beobachtungen von Oberflächenstörungen und aus zielgerichteten Züchtungsexperimenten hervorgeht, Wachstumsinstabilitäten, hervorgerufen durch diffusionsbedingte Inhomogenität der Überschreitung über der Wachstumsfront. Durch die Einführung besonderer Verfahrensweisen der Züchtung und Wahl bestimmter Parameter gelang es, volle Kristalle größerer Abmessungen, bis zu einem Millimeter in Querrichtung, zu erhalten. Veröffentlichungen zum Hohlwachstum anderer Substanzen aus der Gasphase werden referiert.

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The structure and growth of hollow conical single crystals of cadmium sulphide

Cited by 17 publications

References 9 publications

Quantitative Plane-Resolved Crystal Growth and Dissolution Kinetics by Coupling In Situ Optical Microscopy and Diffusion Models: The Case of Salicylic Acid in Aqueous Solution

Quantitative Plane-Resolved Crystal Growth and Dissolution Kinetics by Coupling In Situ Optical Microscopy and Diffusion Models: The Case of Salicylic Acid in Aqueous Solution

Surfactant Effects on Hydrate Crystallization at the Water–Oil Interface: Hollow-Conical Crystals

Oberflächenstörungen und Hohlwachstum bei der Züchtung von β‐Kupferphthalocyanin‐Einkristallen aus der Gasphase

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