On the relation between etch pits or growth hillocks and dislocations on the (111) faces of potassium aluminium alum

Enckevort, W.J.P. van; Linden, W. H. van der

doi:10.1016/0022-0248(79)90242-2

Cited by 40 publications

(10 citation statements)

References 9 publications

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“…Similar surface hillocks have also been observed on ZHS plates and were proposed to be a result of screw dislocations. 29,40 We believe that the growth of ZHDS NMs was also driven by screw dislocations because of the similar crystal structures and surface hillock features. In order to further verify this mechanism, the morphology of ZHDS NMs at different growth time points was investigated by TEM (Figure S3).…”

mentioning

confidence: 96%

Substrate-Free Self-Assembly Approach toward Large-Area Nanomembranes

Wang

Seo

et al. 2012

ACS Nano

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Free-standing two-dimensional nanostrucutures, such as graphene and semiconductor nanomembranes (NMs) featuring their integration with flexible polymer substrates, address applications in which electronic devices need to be stretchable or conformally positioned to nonplanar surfaces. We report a surfactant-directed surface assembly approach to producing large-area NMs at the water-air interface. The NMs were produced by employing the surfactants as templates as well as incorporating them in the crystal structures. By using excess amount of sodium dodecylsulfate (SDS), a tightly packed monolayer of dodecylsulfate (DS) ion was formed and directed the crystallization of submillimeter-sized zinc hydroxy dodecylsulfate (ZHDS) single-crystalline NMs over the entire water surface. This free-standing NM can be readily transferred to an arbitrary substrate and converted to ZnO via heat treatment. A flexible thin-film transistor was also fabricated using the transferred NMs and demonstrated reasonably good n-type transport properties. This approach circumvented the needs of single-crystalline substrates for making large-area NMs from materials that do not possess a laminate structure. It is a low-cost and large-scale synthesis technique and has great potential in developing NMs and flexible devices from various functional materials that are not feasible by conventional selective etching or delamination approaches.

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confidence: 96%

Substrate-Free Self-Assembly Approach toward Large-Area Nanomembranes

Wang

Seo

et al. 2012

ACS Nano

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“…In addition to having a narrow initial distribution, crystals produced by initial breeding may be presumed to be well-formed in comparison to those from contact nucleation, and therefore observa- tions of growth behavior are not confounded with variations in crystal structure due to the nucleation mechanism. Potassium alum was selected for these experiments because both size-dependent growth and growth rate dispersion have been used to explain its behavior in MSMPR crystallizers, and because it grows by a dislocation mechanism at low to moderate supersaturation (Bennema, 1967;Van Enckevort and Van der Linden, 1979). These experiments employed a constant temperature batch crystalfizer shown in Figure 1.…”

Section: Methodsmentioning

confidence: 99%

Size‐dependent crystal growth—A manifestation of growth rate dispersion in the potassium alum‐water system

Girolami

Rousseau

1985

AIChE Journal

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Growth of potassium alum crystals was characterized by the advance rates of crystals on the leading edge of population distributions and by the advance rates of the modes of these distributions. Growth rates of crystals on the leading edge appeared to follow size-dependent kinetics, but the observed spread of the distribution about the average size was much greater than would be expected from size-dependent growth alone. The spread of the distribution was correlated with the extent of growth determined from the net advance of the average crystal size. These quantitative and qualitative results show that what has often been referred to as size-dependent growth is in fact a manifestation of growth rate dispersion. M SCOPEBoth growth rate dispersion and size-dependent growth have been observed to occur under specific conditions in the aqueous potassium alum system. Data on this and other systems often exhibit characteristics of these growth anomalies, and it has been unclear to what extent each mechanism of growth rate variability contributes to or controls the measured growth kinetics and the development of a crystal size distribution. The importance of being able to identify the correct growth mechanism is based on the role it plays in obtaining crystallization kinetics from experimental or operating data, and on the use of such data for the design of large-scale crystallizers.The analysis of crystal size distributions to determine nucleation and growth kinetics requires a knowledge of the relationship of growth rate to crystal size. Such analyses are simple if all crystals in a population grow at identical rates and have no dependence on size. Deviations from invariant crystal growth have been noted for quite some time, but it is only recently that such deviations have been attributed to growth rate dispersion rather than size-dependent growth. Distinction between these two sources of anomalous growth is difficult because their effect on a crystal size distribution is the same: they cause a distribution to spread during growth and, for perfectly mixed crystallizers, they indicate higher nuclei population densities than would be expected for invariant crystal growth. This similarity can cause crystal size distributions obtained through one of the anomalous growth mechanisms to be misinterpreted as the result of the other. In such cases, using correlations based on the incorrect mechanism could lead to a serious errors in scale-up and design.The objectives of this study were to characterize the effects of growth rate variability on the form of developing crystal size distributions of both large and small potassium alum crystals, to separate the effects of size-dependency and growth rate dispersion, and to develop correlations of the observed behavior that could be used to analyze potassium alum systems and give qualitative guidance to the behavior of other systems. CONCLUSIONS AND SIGNIFICANCEGrowth rate variability, whether the result of size-dependent growth or growth rate dispersion, causes an increase in the s...

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“…Both authors discuss the difficulties in maintaining the surface of the as-grown crystals for microscopic investigations, and the working principles of modern optical microscopic techniques. Enckevort discusses the results of the post growth investigations of the (101) faces of ADP and KDP crystals [129], (010) face of KAP [131,132], (001) face of nickel sulfate hexahydrate [134], and (111), (001) and the (101) faces of potassium alum crystals [128,197]. On the (101) faces of KDP and ADP crystals, the surface features imply three different growth mechanisms, namely, cooperating macro-spiral growth, single spiral growth, and two-dimensional nucleation growth are observed.…”

Section: Application To Crystal Growthmentioning

confidence: 99%