Diffusion in Crystalline and Amorphous Solids

1985 ◽  
Vol 57 ◽  
Author(s):  
David Lazarus
Keyword(s):  
Point Defects ◽  
Amorphous Materials ◽  
Essential Role ◽  
Volume Diffusion ◽  
Bulk Diffusion ◽  
Amorphous Solids ◽  
Crystalline Solids ◽  
Simple Point ◽  
Diffusion Mechanisms

AbstractDecades of work by a wide variety of techniques were required to establish unambiguously the essential role of simple – and sometimes not so simple – “point” defects in mediating bulk diffusion in crystalline solids. Amorphous solids present new problems for establishing basic diffusion mechanisms. Most experimental techniques which work well for study of diffusion in crystalline solids are useless for study of amorphous materials because of their inherent nonequilibrium structures. A survey of some current results also gives a strong impression that more complex basic mechanisms than simple point defects may be required to account for volume diffusion in these materials.

Fermi-Level Effect, Electric Field Effect, and Diffusion Mechanisms in GaAs Based III-V Compound Semiconductors

1998 ◽  
Vol 527 ◽  
Author(s):  
T. Y. Tan ◽  
C.-H. Chen ◽  
U. Gösele ◽  
R. Scholz
Keyword(s):  
Electric Field ◽  
Fermi Level ◽  
Point Defects ◽  
Field Effect ◽  
Pressure Effect ◽  
Electric Field Effect ◽  
Diffusion Mechanisms ◽  
And Diffusion ◽  
Level Effect

ABSTRACTDiffusion mechanisms and point defects in GaAs and related III-V compounds are discussed. An understanding of the As sublattice situation has been arrived at fairly recently and is presently tentative. Understanding of the Ga sublattice situation has become more acceptable in that experimental results are consistently explained by the Fermi-level effect and the As4 pressure effect. On the Ga sublattice, though controversies still exist, some are readily resolved by noting the role of the electric field produced by semiconductor electrical junctions, physical junctions, and surfaces.

Defect Engineering in SI:ER Technology

1996 ◽  
Vol 422 ◽  
Author(s):  
N. A. Sobolev ◽  
O. V. Alexandrov ◽  
M. S. Bresler ◽  
V. V. Emtsev ◽  
O. B. Gusev ◽  
...  
Keyword(s):  
Point Defects ◽  
Essential Role ◽  
Defect Formation ◽  
Defect Engineering ◽  
Intrinsic Point Defects ◽  
Related Donor ◽  
Non Equilibrium

AbstractRecent results contributing to our understanding of mechanisms of defect formation and excitation of Er luminescence in Si:Er system are presented. An essential role of non-equilibrium intrinsic point defects in Er-related defects formation for both implanted and in-diffused Si:Er structures is demonstrated.The data of electroluminescence (EL) measurements evidence that the Er3+ excitation occurs via capture of free excitons on neutral Er-related donor centers with subsequent Augerrecombination of bound excitons.

scholarly journals Role of configurational entropy in the thermodynamics of clusters of point defects in crystalline solids

2005 ◽  
Vol 72 (1) ◽  
Author(s):  
Sumeet S. Kapur ◽  
Manish Prasad ◽  
John C. Crocker ◽  
Talid Sinno
Keyword(s):  
Point Defects ◽  
Configurational Entropy ◽  
Crystalline Solids

Solid-Phase Epitaxy - Role of Point Defects in Amorphous Solids

1993 ◽  
Vol 319 ◽  
Author(s):  
T.K. Chaki
Keyword(s):  
Epitaxial Growth ◽  
Point Defects ◽  
Solid Phase ◽  
Ion Irradiation ◽  
Amorphous Solid ◽  
Amorphous Layer ◽  
Amorphous Solids ◽  
Solid Phase Epitaxy ◽  
Self Diffusion

AbstractA model of solid-phase epitaxial growth (SPEG), explaining enhancing effects of ion-irradiation and dopants, is presented. The crystallization is by the adjustment of atomic positions in the amorphous side of the crystalline/amorphous (c-a) interface due to self-diffusion in the amorphous solid, assisted by a freeenergy decrease associated with the transformation from the amorphous (a) to crystalline (c) phase. Irradiation and electrically active dopants increase the selfdiffusivity of a-phase by generating point defects in the amorphous layer and thus enhance crystallization. An expression for the velocity of epitaxial growth is derived. The low activation energy of ion-induced SPEG is due to recombination of point defects in the a-phase.

Bulk Diffusion of Homovalent Non-Magnetic Atomic Probes of Titanium and Zirconium in Tungsten Single Crystals

2011 ◽  
Vol 319-320 ◽  
pp. 1-11 ◽  
Author(s):  
S.M. Klotsman ◽  
G.N. Tatarinova ◽  
Alexander N. Timofeev
Keyword(s):  
Single Crystals ◽  
Point Defects ◽  
Diffusion Coefficients ◽  
Periodic Table ◽  
Secondary Ion Mass Spectrometry ◽  
Volume Diffusion ◽  
Bulk Diffusion ◽  
The Self ◽  
Self Diffusion ◽  
Secondary Ion

The bulk diffusion of homovalent non-magnetic atomic probes (APs) from the IVB group of the periodic table of elements (PTE) – Ti and Zr in tungsten single crystals was investigated by sec-tioning, using secondary ion mass spectrometry (SIMS). The Arrhenius dependences had the fol-lowing parameters: DWTi - (D0)WTi = (3.00.4 ) x 10-4 m2s-1, enthalpy QWTi = (576 ± 9) kJ/mole; DWZr - (D0)WZr = (2.3  0.6) x 10-4 m2s-1, QWZr = (561 9) kJ/mole. The measured parameters (D0,Q)WTi,Zr of diffusion of Ti and Zr atomic probes (APs) in W are in accord with the empirical correlation: the diffusion coefficients of the substitutional APs coincide with the self-diffusion coefficients in W at (Tm)W – its melting temperature. Enthalpies QWTi,Zr,Hf of the volume diffusion of homovalent non-magnetic APs of the IVB group of periodic table of elements (PTE) - Ti, Zr and Hf increase with the decrease of relaxation volumes of the complexes «vacancy-IVBAP» in W lattice. The energies (E)WvacIVBAP of elastic relaxation of the complexes «vacancy-IVBAP» in W lattice were estimated. Electron contributions EDN to the energies EWvacIVBAP of interaction of the point defects in complexes «vacancy-IVBAP» increase relative to value EWvacIIIBAP of interac-tion of the point defects in complexes «vacancy-IIIBAP» with the growth of d-electrons number in comparison with the complexes «vacancy-IIIBAP».

Contrast From Point Defects in The Infinitesimal Approximation

1980 ◽  
Vol 38 ◽  
pp. 350-351
Author(s):  
L. J. Sykes ◽  
J. J. Hren
Keyword(s):  
Electron Microscope ◽  
Point Defects ◽  
Broad Class ◽  
Stacking Fault ◽  
Crystalline Solids ◽  
Dislocation Loops ◽  
Analytical Expression ◽  
Stacking Fault Tetrahedra

In electron microscope studies of crystalline solids there is a broad class of very small objects which are imaged primarily by strain contrast. Typical examples include: dislocation loops, precipitates, stacking fault tetrahedra and voids. Such objects are very difficult to identify and measure because of the sensitivity of their image to a host of variables and a similarity in their images. A number of attempts have been made to publish contrast rules to help the microscopist sort out certain subclasses of such defects. For example, Ashby and Brown (1963) described semi-quantitative rules to understand small precipitates. Eyre et al. (1979) published a catalog of images for BCC dislocation loops. Katerbau (1976) described an analytical expression to help understand contrast from small defects. There are other publications as well.

Essential role of Sharpin in TNFα dependent NFκB activation in primary hepatocytes

2012 ◽  
Vol 50 (01) ◽  
Author(s):  
N Lange ◽  
S Sieber ◽  
A Erhardt ◽  
G Sass ◽  
HJ Kreienkamp ◽  
...  
Keyword(s):  
Essential Role ◽  
Primary Hepatocytes

Different Abilities of Thrombin Receptor Activating Peptide and Thrombin to Induce Platelet Calcium Rise and Full Release Reaction

1995 ◽  
Vol 74 (05) ◽  
pp. 1323-1328 ◽  
Author(s):  
Dominique Lasne ◽  
José Donato ◽  
Hervé Falet ◽  
Francine Rendu
Keyword(s):  
Essential Role ◽  
Calcium Influx ◽  
Dense Granule ◽  
Receptor Interaction ◽  
Thrombin Receptor ◽  
Release Reaction ◽  
External Calcium ◽  
Maximum Rise ◽  
Granule Release

SummarySynthetic peptides (TRAP or Thrombin Receptor Activating Peptide) corresponding to at least the first five aminoacids of the new N-terminal tail generated after thrombin proteolysis of its receptor are effective to mimic thrombin. We have studied two different TRAPs (SFLLR, and SFLLRN) in their effectiveness to induce the different platelet responses in comparison with thrombin. Using Indo-1/AM- labelled platelets, the maximum rise in cytoplasmic ionized calcium was lower with TRAPs than with thrombin. At threshold concentrations allowing maximal aggregation (50 μM SFLLR, 5 μM SFLLRN and 1 nM thrombin) the TRAPs-induced release reaction was about the same level as with thrombin, except when external calcium was removed by addition of 1 mM EDTA. In these conditions, the dense granule release induced by TRAPs was reduced by over 60%, that of lysosome release by 75%, compared to only 15% of reduction in the presence of thrombin. Thus calcium influx was more important for TRAPs-induced release than for thrombin-induced release. At strong concentrations giving maximal aggregation and release in the absence of secondary mediators (by pretreatment with ADP scavengers plus aspirin), SFLLRN mobilized less calcium, with a fast return towards the basal level and induced smaller lysosome release than did thrombin. The results further demonstrate the essential role of external calcium in triggering sustained and full platelet responses, and emphasize the major difference between TRAP and thrombin in mobilizing [Ca2+]j. Thus, apart from the proteolysis of the seven transmembrane receptor, another thrombin binding site or thrombin receptor interaction is required to obtain full and complete responses.

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