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Journal ArticleDOI

A New Mechanism for the Crystallization and Growth of Ionic Crystals, with Special Reference to KCl in the Presence of Pb2+ Ions.

01 Jan 1968-Israel Journal of Chemistry (WILEY‐VCH Verlag)-Vol. 6, Iss: 1, pp 69-72
About: This article is published in Israel Journal of Chemistry.The article was published on 1968-01-01. It has received 17 citations till now. The article focuses on the topics: Crystallization.
Citations
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Journal ArticleDOI
Abstract: A cauliflower structure is a granular film composed of spherical particles similar in size, each with numerous nanoscale nodules on its surface. The structure is produced during certain chemical vapour deposition (CVD) processes for diamond and silicon thin film growth. A classical account in terms of atomic unit deposition fails to explain the growth of such a cauliflower structure, as it requires a gas phase of much higher supersaturation than for onset of diffusion controlled growth. Another interesting and somewhat puzzling phenomenon encountered during a diamond CVD process is that while diamond is depositing on a graphite substrate, carbon atoms in the graphite itself are etched away into the vapour phase; that is, experience evaporation. Again, an elementary kinetic barrier mechanism fails to explain such CVD deposition of a less stable diamond phase combined with simultaneous evaporation of a stable graphite phase. In order to account for such puzzling CVD phenomena and others, a theory o...

75 citations

Journal ArticleDOI
TL;DR: In this article, negative charged clusters of 3000-18000 atomic mass units were experimentally confirmed under typical process conditions of hot-filament diamond CVD using gas mixtures of 1-5% CH4 and H2.

65 citations

Journal ArticleDOI
TL;DR: In this paper, the critical role of charged nanoclusters and nanoparticles in the growth of thin films and nanostructures by chemical vapour deposition (CVD) is reviewed.
Abstract: The critical role of charged nanoclusters and nanoparticles in the growth of thin films and nanostructures by chemical vapour deposition (CVD) is reviewed. Advanced nanoparticle detection techniques have shown that charged gas-phase nuclei tend to be formed under conventional processing conditions of thin films and nanostructures by thermal, hot-wire and plasma CVD. The relation between gas-phase nuclei and thin film and nanostructure growth has not been clearly understood. In this review it will be shown that many films and nanostructures, which have been believed to grow by individual atoms or molecules, actually grow by the building blocks of such charged nuclei. This new growth mechanism was revealed in an attempt to explain many puzzling phenomena involved in the gas-activated diamond CVD process. Therefore, detailed thermodynamic and kinetic analyses will be made to draw the conclusion that the well-known phenomenon of deposition of less stable diamond with simultaneous etching of stable graphite should be an indication of diamond growth exclusively by charged nuclei formed in the gas phase. A similar logic was applied to the phenomenon of simultaneous deposition and etching of silicon, which also leads to the conclusion that silicon films by CVD should grow mainly by the building blocks of charged nuclei. This new mechanism of crystal growth appears to be general in many CVD and some physical vapour deposition (PVD) processes. In plasma CVD, this new mechanism has already been utilized to open a new field of plasma-aided nanofabrication.

60 citations

Journal ArticleDOI
TL;DR: In this paper, a threshold treatment process is used for the control of scale in sea water evaporators, and the search for improved additives is made difficult by the lack of understanding of the mechanism of the process.

43 citations

Journal ArticleDOI
TL;DR: In this paper, the precipitation of calcium carbonate has been studied in the absence and presence of hydroxyethylidene-1, 1-diphosphonic acid (HEDP).

30 citations

References
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TL;DR: In this paper, single crystals of potassium chloride were grown from aqueous solutions under carefully controlled conditions of supersaturation, agitation, and impurity lead chloride concentration, and the growth rate of the (100) face was determined.
Abstract: Single crystals of potassium chloride were grown from aqueous solutions under carefully controlled conditions of supersaturation, agitation, and impurity lead chloride concentration. The growth rate of the (100) face was determined.It was found that PbCl2 concentrations as low as 10−8 moles PbCl2/mole KCl decreased the rate of growth, and the retardation increased markedly with increasing PbCl2 concentration. The growth process changed from a layer type to a dendritic form over a small supersaturation range. Mass transfer rates of both KCl and PbCl2 from the solution to the crystal face were estimated and conditions delineated where each may be the rate‐controlling step. A mechanism is proposed to account for the formation of crystal clusters on the surface of KCl at slow stirring rates.

24 citations