On the growth of ammonium nitrate(III) crystals

Vogels, L.J.P.; Marsman, H.A.M.; Verheijen, Marcel A.; Bennema, P.; Elwenspoek, M.

doi:10.1016/0022-0248(90)90242-d

Cited by 19 publications

(12 citation statements)

References 25 publications

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“…The growth rate R versus F curves shown in Fig. 7 can be expected for the growth of singular surfaces with dislocations and qualitatively resemble those predicted theoretically 5,11–13,29 and observed experimentally 8–10,17 for the growth of single crystals in supersaturated or supercooled liquid with screw dislocations. Because the dislocations in the corundum crystal pieces are not likely to be pure screw dislocations and F is only approximately represented by , these R versus F curves are not expected to agree closely with those predicted for screw dislocations 5,8–13 .…”

Section: Resultssupporting

confidence: 80%

“…Direct observations of step nucleation and growth have been made in a 2Zn–insulin crystal by atomic force microscopy, 7 and the dependence of the surface growth rate v on the driving force or the supercooling F for Ga 8 and 4 He 9,10 has been observed to agree with the predicted v – F relationship. It is well known that screw dislocations enhance the growth rates at low driving forces by spiral step growth 5,8–21 . It was proposed that the edge dislocations could also enhance the surface migration rates 22–24 …”

Section: Introductionmentioning

confidence: 99%

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Migration of Corundum Crystal Basal Surfaces in a Matrix of Fine Alumina Grains and Anorthite Liquid

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Kim

Yoon

2005

Journal of the American Ceramic Society

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Corundum crystals with basal surfaces have been embedded in a matrix of fine alumina grains and 15 wt% anorthite and heat treated at 1620°C. During the heat treatment, the fine alumina grains and the corundum crystals grow. The corundum basal surfaces that have been scratched grow most rapidly and those with a low dislocation etch pit density grow most slowly. The corundum basal surfaces with a high dislocation etch pit density grow at an intermediate rate. When the matrix alumina grains are very fine in the initial heat‐treatment stage, all three corundum basal planes grow at approximately the same rate, and, as the matrix grains coarsen, the growth rates of the basal surfaces diverge. The plots of the migration rates of the basal surfaces and the inverse average size of the matrix grains are non‐linear and depend on the estimated dislocation content at the basal surfaces. Such a growth behavior of the basal surfaces resembles those of the singular surfaces of a single crystal growing in a fluid. The results show that dislocations in the grains are important in abnormal growth of grains in liquid matrix.

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Section: Resultssupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Migration of Corundum Crystal Basal Surfaces in a Matrix of Fine Alumina Grains and Anorthite Liquid

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Kim

Yoon

2005

Journal of the American Ceramic Society

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Section: Resultsmentioning

confidence: 99%

“…If a singular grain boundary is rapidly moving, its shape may become curved by kinetic roughening as a surface. [38][39][40][41][42][43][44] It is therefore possible that not all singular grain boundaries are identified by their shapes in the specimens heat-treated at low temperatures.The grain boundary defaceting transition observed in this Si-iron is similar to those observed in other metals. [13][14][15][16][17][18] The transition temperature of approximately 1 000°C (about 0.73 T m ) also falls into the range of 0.6-0.9 T m observed in other metals, [13][14][15][16][17][18][27][28][29] although the transition temperatures vary among the grain boundaries and depend also on additives and impurities.…”

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confidence: 99%

Temperature Dependence of Grain Boundary Structure and Grain Growth in Bulk Silicon-Iron.

Choi

Yoon

2003

ISIJ International

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Grain boundary shapes and grain growth in bulk 2.61 wt% silicon-iron have been studied by heat-treating at temperatures between 700 and 1 200°C. Initial microstructure with fairly uniform fine grains has been obtained by recrystallization at 800°C for 5 min after deformation. When subsequently heat-treated at 700 and 800°C, a fraction of the grain boundaries have hill-and-valley shapes with several facet planes or kinks. Some of these facet boundary segments are expected to be singular. Abnormal grain growth occurs at 700 and 800°C and is attributed to step growth of the boundaries. When heat-treated at 1 000°C, all grain boundaries are defaceted with smoothly curved shapes, indicating that they are atomically rough. At temperatures above 1 000°C, normal grain growth occurs, because the rough grain boundaries move continuously. This correlation between grain boundary structure and grain growth is consistent with the earlier observations in other metals and oxides. It is thus shown that the abnormal grain growth in this alloy occurs at low temperatures because of the singular grain boundary structure.KEY WORDS: silicon-iron; silicon-steel; abnormal grain growth; grain boundary faceting; singular grain boundary.ing along the grain boundaries using an image analysis program. For the specimens with fine grains, about 500-2 000 grains were measured, and for those with large grains, about 100-300 grains were measured. The grain boundary shapes were also examined in a transmission electron microscope (TEM). Results and DiscussionWet chemical analysis of the heat-treated bar showed that the Si content was 2.61 wt% and the major impurities were P (0.015 wt%), Ni (0.06 wt%), and Cr (0.01 wt%). The C, Mn, and S contents were about 0.005 wt%. The specimens heat-treated at 800°C for 5 min after compressing to 66.7 % in height had typical primary recrystallization structures with fine grains of 8.7 mm in average radius as shown in Fig. 1. The X-ray pole figure and electron back-scattered pattern (EBSP) analysis of these specimens did not show any macroscopic or microscopic texture. Figure 1 is the initial microstructure for all subsequent heat-treatments at various temperatures to observe the grain growth behavior.The grain growth during the heat-treatment at 600°C was very slow. After 250 h at 600°C, the grains were only slightly larger than those shown in Fig. 1. During the heattreatment at 700°C, typical AGG behavior was observed as shown in the microstructures of Fig. 2, and grain size distributions in Fig. 3. After 3 h, some large grains began to appear as shown in Fig. 2(a), and after 24 h, some grains had grown to about 700 mm radius as shown in Fig. 2(d). In Fig. 3, those large grains that could be clearly identified as the abnormal grains are marked by arrows. The fine matrix grains grew slowly as can be seen in Figs. 2 and 3.When the heat-treatment temperature was increased to 800°C, distinct AGG behavior was again observed during 24 h, but the number density of the abnormal grains was larger than that observed at ...

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“…The solutions were left unstirred. The sample cell was then placed into an experimental cell, which was connected to a temperature controlled water bath (similar to the set up described by Vogels et al [11]). In this way strict control of the temperature (70.2 C), and hence supersaturation, could be achieved.…”

Section: Methodsmentioning

confidence: 99%

Nucleation and growth of crystalline ribbons in diastereomeric ephedrine–cyclic phosphoric acid systems

Loh

Enckevort

Vlieg

2004

Journal of Crystal Growth

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On the growth of ammonium nitrate(III) crystals

Cited by 19 publications

References 25 publications

Migration of Corundum Crystal Basal Surfaces in a Matrix of Fine Alumina Grains and Anorthite Liquid

Migration of Corundum Crystal Basal Surfaces in a Matrix of Fine Alumina Grains and Anorthite Liquid

Temperature Dependence of Grain Boundary Structure and Grain Growth in Bulk Silicon-Iron.

Nucleation and growth of crystalline ribbons in diastereomeric ephedrine–cyclic phosphoric acid systems

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