Rapid Cellular Crystal Growth of TiAl-Based Intermetallic without Peritectic Reaction by Melt-Quenching in Ga–In Liquid

An Al–Cu–Fe partial phase diagram involving the icosahedral quasicrystal has been constructed along an Al62.5Cu37.5−xFex (x = 2.5 to 25 at.%) isopleth. The icosahedral quasicrystal forms at 850 °C via a peritectic reaction between a liquid and (Al,Cu) 13Fe4 phase and coexists with a liquid phase at temperature below the peritectic reaction. The icosahedral quasicrystal crystallizes as a primary phase in the temperature range of 760 to 850 °C from alloys surrounded by composition points of Al–Cu–Fe: 62.5–33–4.5, 62.5–34.5–3, 57.5–39.5–3 and 57.5–38.0–4.5 at.%. On the basis of the phase diagram, single grains of the Al–Cu–Fe icosahedral quasicrystal with a maximum size of 5 mm were successfully grown from Al–Cu–Fe melts.

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The relation between the undercooling and the growth rate of YBa2Cu3O6+x superconductive oxide

Journal of Materials Research ◽

10.1557/jmr.1996.0139 ◽

1996 ◽

Vol 11 (5) ◽

pp. 1094-1100 ◽

Cited By ~ 35

Author(s):

Y. Nakamura ◽

A. Endo ◽

Y. Shiohara

Keyword(s):

Growth Rate ◽

Crystal Growth ◽

Linear Dependence ◽

Mass Flux ◽

Peritectic Reaction ◽

Screw Dislocations ◽

Quadratic Dependence

To clarify the effect of undercooling on the crystal growth of Y-123, the growth rate was measured with different undercoolings. The growth rate of the {100} face shows a quadratic dependence of undercooling, while that of the {001} face shows a linear dependence in the sample with nominal 123 composition. In the case with 211-rich composition, the growth rate of each face was larger than that compared with nominal 123 composition since the mass flux from 211 particle for peritectic reaction becomes large. Addition of excess 211 alters the undercooling dependence of Ra from quadratic to linear. It is considered that the entrapment of 211 particles into 123 crystals supplies step sources beside screw dislocations. The growth rate of the {001} face is larger than that of the {100} face up to 26° of undercooling.

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Crystal growth mechanism of YBa2Cu3Oy superconductors with peritectic reaction

Journal of Crystal Growth ◽

10.1016/s0022-0248(07)80039-x ◽

1993 ◽

Vol 128 (1-4) ◽

pp. 757-761 ◽

Cited By ~ 96

Author(s):

T. Izumi ◽

Y. Nakamura ◽

Y. Shiohara

Keyword(s):

Crystal Growth ◽

Growth Mechanism ◽

Peritectic Reaction ◽

Crystal Growth Mechanism

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Montmorillonite Dendrites

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100052286 ◽

1974 ◽

Vol 32 ◽

pp. 454-455

Author(s):

Necip Güven ◽

Rodney W. Pease

Keyword(s):

Crystal Growth ◽

Growth Mechanism ◽

Growth Front ◽

Morphological Features ◽

Dendritic Crystal ◽

Crystal Growth Mechanism

Morphological features of montmorillonite aggregates in a large number of samples suggest that they may be formed by a dendritic crystal growth mechanism (i.e., tree-like growth by branching of a growth front).

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TEM and cathodoluminescence of precipitates in II-VI semiconductors

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100104509 ◽

1988 ◽

Vol 46 ◽

pp. 488-489

Author(s):

Joanna L. Batstone

Keyword(s):

Crystal Growth ◽

Band Gap ◽

Local Strain ◽

Wide Band ◽

Optoelectronic Device ◽

Wide Band Gap ◽

Bulk Crystal Growth ◽

Transmission Electron ◽

Device Applications ◽

Stoichiometry Control

Interest in II-VI semiconductors centres around optoelectronic device applications. The wide band gap II-VI semiconductors such as ZnS, ZnSe and ZnTe have been used in lasers and electroluminescent displays yielding room temperature blue luminescence. The narrow gap II-VI semiconductors such as CdTe and HgxCd1-x Te are currently used for infrared detectors, where the band gap can be varied continuously by changing the alloy composition x.Two major sources of precipitation can be identified in II-VI materials; (i) dopant introduction leading to local variations in concentration and subsequent precipitation and (ii) Te precipitation in ZnTe, CdTe and HgCdTe due to native point defects which arise from problems associated with stoichiometry control during crystal growth. Precipitation is observed in both bulk crystal growth and epitaxial growth and is frequently associated with segregation and precipitation at dislocations and grain boundaries. Precipitation has been observed using transmission electron microscopy (TEM) which is sensitive to local strain fields around inclusions.

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STM studies of crystal growth

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100086179 ◽

1991 ◽

Vol 49 ◽

pp. 374-375

Author(s):

M. G. Lagally

Keyword(s):

Crystal Growth ◽

Molecular Beam ◽

Chemical Vapor ◽

Sputter Deposition ◽

Field Of View ◽

Scanning Tunneling ◽

Wide Field ◽

Tunneling Microscopy ◽

Wide Field Of View ◽

The One

It has been recognized since the earliest days of crystal growth that kinetic processes of all Kinds control the nature of the growth. As the technology of crystal growth has become ever more refined, with the advent of such atomistic processes as molecular beam epitaxy, chemical vapor deposition, sputter deposition, and plasma enhanced techniques for the creation of “crystals” as little as one or a few atomic layers thick, multilayer structures, and novel materials combinations, the need to understand the mechanisms controlling the growth process is becoming more critical. Unfortunately, available techniques have not lent themselves well to obtaining a truly microscopic picture of such processes. Because of its atomic resolution on the one hand, and the achievable wide field of view on the other (of the order of micrometers) scanning tunneling microscopy (STM) gives us this opportunity. In this talk, we briefly review the types of growth kinetics measurements that can be made using STM. The use of STM for studies of kinetics is one of the more recent applications of what is itself still a very young field.

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Cristal-growth dynamics of n-doped gaAs

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100132352 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1544-1545

Author(s):

Pham V. Huong ◽

Stéphanie Bouchet ◽

Jean-Claude Launay

Keyword(s):

Crystal Growth ◽

Spatial Resolution ◽

Epitaxial Layer ◽

Outer Surface ◽

Gaas Substrate ◽

Structural Modification ◽

Growth Dynamics ◽

Argon Laser ◽

High Anisotropy ◽

Crystal Gaas

Microstructure of epitaxial layers of doped GaAs and its crystal growth dynamics on single crystal GaAs substrate were studied by Raman microspectroscopy with a Dilor OMARS instrument equipped with a 1024 photodiode multichannel detector and a ion-argon laser Spectra-Physics emitting at 514.5 nm.The spatial resolution of this technique, less than 1 μm2, allows the recording of Raman spectra at several spots in function of thickness, from the substrate to the outer deposit, including areas around the interface (Fig.l).The high anisotropy of the LO and TO Raman bands is indicative of the orientation of the epitaxial layer as well as of the structural modification in the deposit and in the substrate at the interface.With Sn doped, the epitaxial layer also presents plasmon in Raman scattering. This fact is already very well known, but we additionally observed that its frequency increases with the thickness of the deposit. For a sample with electron density 1020 cm-3, the plasmon L+ appears at 930 and 790 cm-1 near the outer surface.

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