Reactive crystal growth in two dimensions: Silicon nitride on Si(111)

1995 ◽  
Vol 51 (24) ◽  
pp. 17891-17901 ◽  
Author(s):  
E. Bauer ◽  
Y. Wei ◽  
T. Müller ◽  
A. Pavlovska ◽  
I. S. T. Tsong
Keyword(s):  
Crystal Growth ◽  
Silicon Nitride ◽  
Two Dimensions

scholarly journals Crystal Growth and the Formation of Spikes in the Surface of Supercooled Water

1960 ◽  
Vol 3 (28) ◽  
pp. 698-704 ◽  
Author(s):  
J. Hallett
Keyword(s):  
Crystal Growth ◽  
Single Crystal ◽  
Composite Structure ◽  
Liquid Surface ◽  
Supercooled Water ◽  
Two Dimensions ◽  
Optic Axis ◽  
Ice Crystals ◽  
Precise Form ◽  
Initial Nucleus

Abstract Observations made of ice crystals growing on the surface of supercooled water show that they take the form of a composite structure, called surface needles, each of which consists of dendrites growing into the liquid, and of ribs growing in the liquid surface. Each needle is a single crystal. The precise form of the needle is determined by the orientation of the initial nucleus. If its optic axis is near normal to the surface, growth occurs rapidly in two dimensions and covers a much larger proportion of the surface than is covered by the narrow surface needles, so that ice forming this way appears to have its optic axis vertical. Hollow ice spikes observed on pools are shown to have been formed by the freezing of water forced from beneath the surface at the intersection of two or three surface needles, the shape of the spike depending on their orientation.

Cutting Simulation of Laser Assisted Milling of Silicon Nitride Ceramics Using PFC2D

2009 ◽  
Author(s):  
Xinwei Shen ◽  
Shuting Lei
Keyword(s):  
Silicon Nitride ◽  
Distinct Element ◽  
Cutting Temperature ◽  
Two Dimensions ◽  
Particle Flow Code ◽  
Temperature Dependent ◽  
Cutting Simulation ◽  
Nitride Ceramics ◽  
Ceramic Machining ◽  
Distinct Element Code

Since laser assisted milling (LAMill) exhibits complicated characteristics in ceramic machining, this paper applies a distinct-element code, PFC2D (Particle Flow Code in Two-Dimensions), to conduct cutting simulation of laser assisted slab milling and explore its machining mechanism. The microstructure of a β-type silicon nitride ceramic (β-Si3N4) is modeled at grain scale. Clusters are used to simulate the rod-like grains of β-Si3N4. Parallel bonds are employed to represent the connection between intergranular glass phase and grains. A temperature-dependent PFC specimen is created for simulation of LAMill. A special milling cutter is designed for improving the computing efficiency. Simulation results show that the cutting force is strongly related to crack formation and propagation. The specific cutting energy decreases as the cutting temperature increases.

Seven basic regimes of steady crystal growth in two dimensions

1994 ◽  
Vol 77 (1-2) ◽  
pp. 199-215 ◽  
Author(s):  
D. J. Gates ◽  
M. Westcott
Keyword(s):  
Crystal Growth ◽  
Two Dimensions

Crystal growth in supercritical ammonia using high surface area silicon nitride feedstock

2004 ◽  
Vol 261 (1) ◽  
pp. 99-104 ◽  
Author(s):  
Stefan Kaskel ◽  
Meikh Khanna ◽  
Bodo Zibrowius ◽  
Hans-Werner Schmidt ◽  
Dirk Ullner
Keyword(s):  
Crystal Growth ◽  
Silicon Nitride ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Supercritical Ammonia

Graphical modelling of crystal aggregates and its relevance to cement diagnosis

1983 ◽  
Vol 309 (1509) ◽  
pp. 465-502 ◽  
Keyword(s):  
Crystal Growth ◽  
Boundary Migration ◽  
Morphological Type ◽  
Two Dimensions ◽  
Crystallographic Form ◽  
Carbonate Cements ◽  
Graphical Modelling ◽  
Growth Diagram ◽  
Two Generations ◽  
Active Substrate

The identification of carbonate cements in rock sections is accomplished by means of textural criteria. Some of these criteria, relating to crystal fabric, may be modelled graphically in crystal growth diagrams. Existing crystal growth diagrams are oversimplified. Three new crystal growth diagrams are presented for calcite {1011}, {4041} and {0112} rhombohedra The crystals are envisaged as growing by zones of equal width from an inert substrate. The patterns that growth zones create on cuts through individual crystals are used as templates to produce the crystal growth diagrams. 151 crystals seeded on the substrate, on both sides of the crystal growth diagram, are considered to grow at identical rates and impinge on one another. The three crystal growth diagrams illustrate features of crystal initiation and shape in two dimensions not found in previously published diagrams. The rate of maturation of the crystal fabric away from the substrate is shown to depend partly on crystallographic form. Optical elongation is also shown to be related to crystallographic form. The enfacial junction, a special type of triple junction, is shown to be absent from the crystal growth diagrams. The diagrams presented are constrained. Changes in (i) the direction of crystal cutting, (ii) crystallographic form during growth, (iii) the number of crystallographic forms at one time, (iv) the positioning of nuclei, (v) shape of the substrate, and (vi) the change to an active substrate where epitaxy occurs, would all change the character of the crystal growth diagram. The technique of using a list of textural criteria for identifying cements is rejected. Such lists may be used to identify the morphological type of crystal aggregate. After examination of other properties, the decision as to whether that type of aggregate is cement or not can be made. The recognition of impingement growth is made easy if all stages of maturation are present. Where insufficient space is available for mature growth to develop, recognition must rely on features other than textural. A calcite aggregate developed in a Permian bryozoan biolithite is used to illustrate immature impingement growth. This aggregate is identified as of impingement type principally from the arrangement of growth zonation shown in each crystal by cathodoluminescence. The enfacial junction, often regarded as the least equivocal criterion for the recognition of cements, is absent from the crystal growth diagrams and the Permian biolithite. The origin of enfacial junctions in a Lower Carboniferous spar is thought to be due either to unusual sporadic growth inhibition or, more likely, to intercrystalline boundary migration due to dissolution. Enfacial junctions are common in ancient spars: if generated by intercrystalline dissolution considerable quantities of CaCO 3 have been liberated. Enfacial junctions also develop at the junction of two generations of crystals not exhibiting epitaxy.

Surface Morphology and Composition Characterization at the Initial Stages of AlN Crystal Growth

2000 ◽  
Vol 639 ◽  
Author(s):  
B. Liu ◽  
Y. Shi ◽  
L. Liu ◽  
J.H. Edgar ◽  
D.N. Braski
Keyword(s):  
Growth Rate ◽  
Crystal Growth ◽  
Silicon Nitride ◽  
Chemical Composition ◽  
Surface Morphology ◽  
Stages Of Growth ◽  
Initial Stage ◽  
Bare Substrate

ABSTRACTThe morphology and composition of AlN crystals on 6H-SiC (0001) at the initial stage of crystal growth by sublimation re-condensation technique were investigated by SEM and SAM. Discontinuous AlN coverage occurred after 15 minutes growth. The AlN nuclei size, and growth rate increased as temperature increased or pressure decreased. The SiC substrate decomposed leaving hexagonal hillocks; simultaneously, the AlN nucleated on these SiC hillocks apparently rotated by 15° to 30°. The chemical composition of the substrate and different AlN crystal facets were characterized by SAM. The bare substrate area was stoichiometric SiC with insignificant conversion to silicon nitride, while Si and C preferentially incorporated in the AlN at the initial stages of growth on specific crystal planes.

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