Non Parabolic Shift of Interfaces and Effect of Diffusion Asymmetry on Nanoscale Solid State Reactions

2009 ◽  
Vol 7 ◽  
pp. 43-49 ◽  
Author(s):  
Dezső L. Beke ◽  
Z. Erdélyi ◽  
Z. Balogh ◽  
Csaba Cserháti ◽  
G.L. Katona
Keyword(s):  
Experimental Data ◽  
Solid State ◽  
Interface Reaction ◽  
Diffuse Interface ◽  
Solid State Reactions ◽  
Diffusion Couples ◽  
Parent Materials ◽  
Parabolic Law ◽  
And Shifts ◽  
Interface Reaction Control

In a set of recent papers we have shown that the diffusion asymmetry in diffusion couples (the diffusion coefficient is orders of magnitude larger in one of the parent materials) leads to interesting phenomena: i) sharp interface remains sharp and shifts with non Fickian (anomalous) kinetics [1-5], ii) originally diffuse interface sharpens even in ideal (completely miscible) systems [6,7], iii) an initially existing thin AB phase in A/AB/B diffusion couple can be dissolved [8], iv) there exists a crossover thickness (typically between few nanometers and 1m) above which the interface shift turns back to the Fickian behaviour [9], v) the growth rate of a product of solid state reaction can be linear even if there is no any extra potential barrier present (which is the classical interpretation of the “interface reaction control” for linear kinetics) [10]. These latter results will be summarized and reformulated according to the usual expression for linear-parabolic law containing the interdiffusion coefficient, D, and interface transfer coefficient, K. Relation between the activation energies of D and K will be analyzed and compared with available experimental data.

Co Anomalous Growth Kinetics of the CoSi Reaction Layer in a Si/System

2008 ◽  
Vol 273-276 ◽  
pp. 99-104
Author(s):  
Csaba Cserháti ◽  
Györgyi Glodán ◽  
A. Csik ◽  
G.A. Langer ◽  
Z. Erdélyi ◽  
...  
Keyword(s):  
Solid State ◽  
Electrical Resistance ◽  
Interface Reaction ◽  
Solid State Reactions ◽  
Heat Treated ◽  
Different Temperatures ◽  
Amorphous Si ◽  
Kinetics Of ◽  
Interface Reaction Control ◽  
Anomalous Growth

Solid state reactions between amorphous Si and crystalline Co have been investigated by 4W electrical resistance and TEM. Multilayered (with 10 periods of 5nm a-Si/5nm Co and 10 nma- Si/10nm Co layers) as well as tri-layered samples (20nm a-Si/3nmCoSi/6nm Co) were produced by magnetron sputtering and isothermally heat treated at different temperatures between 473 and 523K. From the time evolution of the normalized resistance the kinetics of the process were determined by fitting a power law, tk, and k was between 0.8 and 1. Possibility of the interface reaction control and/or the effect of the diffusion asymmetry (which was recently published for the non-parabolic interface shifts on the nanoscale) will be discussed.

Silicide Formation Reactions in a-Si/Co Multilayered Samples

2008 ◽  
Vol 277 ◽  
pp. 3-8
Author(s):  
Z. Balogh ◽  
Csaba Cserháti ◽  
Z. Erdélyi ◽  
A. Csik ◽  
G.A. Langer ◽  
...  
Keyword(s):  
Growth Rate ◽  
Solid State ◽  
Synchrotron Radiation ◽  
Magnetron Sputtering ◽  
Interface Reaction ◽  
Solid State Reactions ◽  
Silicide Formation ◽  
Parabolic Kinetics ◽  
Heat Treated ◽  
Interface Reaction Control

Solid state reactions between amorpous Si and crystalline Co have been investigated by synchrotron radiation at Bessy (Berlin, Germany). The multilayered samples (with 10 periods of a-Si(15 nm)/Co(15 nm) layers) were produced by magnetron sputtering and isothermally heat treated at temperatures between 523 and 593 K. From the time evolution of the XRD spectra first the growth rate of the CoSi phase as well as the decay rate of the Co layer we determined (at 523 and 543 K). The kinetics were described by a power law; tk, and for the growth of CoSi k=0.65 while for the loss of the Co the k=0.77 was obtained, respectively. At higher temperatures (at 573 and 593 K) the formation and growth of the Co2Si layer, at the expense of the Co and already existing CoSi layers, was observed with exponents of about 1 for all the above kinetics. These results, together with the results of resistance kinetics measurements, in similar multilayered as well as bi-layered samples at similar temperatures, providing similar exponents will be presented. Possibility of the interface reaction control and/or the effect of the diffusion asymmetry (which was recently published for the interpretation of solid state reactions with non-parabolic kinetics on the nanoscale) will be discussed.

TEM STUDIES OF THE MICROMECHANISMS OF SOLID STATE REACTIONS IN Ni-Zr BULK DIFFUSION COUPLES

1990 ◽  
Vol 51 (C4) ◽  
pp. C4-121-C4-130
Author(s):  
U. KÖSTER ◽  
R. PRIES ◽  
G. BEWERNICK ◽  
B. SCHUHMACHER ◽  
M. BLANK-BEWERSDORFF
Keyword(s):  
Solid State ◽  
Bulk Diffusion ◽  
Solid State Reactions ◽  
Diffusion Couples

A Study of the Kinetics and Energetics of Solid State Reactions in Pd/Sn Diffusion Couples

1995 ◽  
Vol 398 ◽  
Author(s):  
R.R. Chromik ◽  
E. J. Cotts
Keyword(s):  
Differential Scanning Calorimetry ◽  
Solid State ◽  
Heat Of Formation ◽  
Solid State Reactions ◽  
Diffusion Couples ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Limited Temperature ◽  
Reaction Constant ◽  
Limited Temperature Range

ABSTRACTUsing differential scanning calorimetry, supplemented by measurements from scanning electron microscopy images, we have investigated solid state reactions in Pd/Sn multilayer composites to form PdSn4 and PdSn3. Planar diffusion couples of Pd and Sn were prepared by means of mechanical co-deformation in a rolling mill. A phase formation sequence was determined using differential scanning calorimetry and x-ray diffraction. Growth of the PdSru phase was studied from room temperature to the melting point of Sn. For temperatures between 430 and 460K diffusion limited growth of PdSn4 was observed. From heat flow data over this limited temperature range, the form of the reaction constant was found to be k2 −k0 exp(−Ea / kbT), where k0= 0.16 cm2/s and Εn= 0.8 eV/atom. Also determined was a heat of formation, ΔHf = −27±1 kJ/mol for PdSn4 from Pd and Sn.

scholarly journals Structure evolution of h.c.p./c.c.p. metal oxide interfaces in solid-state reactions

2018 ◽  
Vol 74 (5) ◽  
pp. 466-480 ◽  
Author(s):  
C. Li ◽  
G. Habler ◽  
T. Griffiths ◽  
A. Rečnik ◽  
P. Jeřábek ◽  
...  
Keyword(s):  
Solid State ◽  
Interface Reaction ◽  
Solid State Reactions ◽  
Structure Evolution ◽  
Growth Stages ◽  
Partial Dislocations ◽  
Wide Range ◽  
Scanning Transmission ◽  
Growth Selection ◽  
Edge Dislocations

The structure of crystalline interfaces plays an important role in solid-state reactions. The Al2O3/MgAl2O4/MgO system provides an ideal model system for investigating the mechanisms underlying the migration of interfaces during interface reaction. MgAl2O4 layers have been grown between Al2O3 and MgO, and the atomic structure of Al2O3/MgAl2O4 interfaces at different growth stages was characterized using aberration-corrected scanning transmission electron microscopy. The oxygen sublattice transforms from hexagonal close-packed (h.c.p.) stacking in Al2O3 to cubic close-packed (c.c.p.) stacking in MgAl2O4. Partial dislocations associated with steps are observed at the interface. At the reaction-controlled early growth stages, such partial dislocations coexist with the edge dislocations. However, at the diffusion-controlled late growth stages, such partial dislocations are dominant. The observed structures indicate that progression of the Al2O3/MgAl2O4 interface into Al2O3 is accomplished by the glide of partial dislocations accompanied by the exchange of Al3+ and Mg2+ cations. The interface migration may be envisaged as a plane-by-plane zipper-like motion, which repeats along the interface facilitating its propagation. MgAl2O4 grains can adopt two crystallographic orientations with a twinning orientation relationship, and grow by dislocations gliding in opposite directions. Where the oppositely propagating partial dislocations and interface steps meet, interlinked twin boundaries and incoherent Σ3 grain boundaries form. The newly grown MgAl2O4 grains compete with each other, leading to a growth selection and successive coarsening of the MgAl2O4 grains. This understanding could help to interpret the interface reaction or phase transformation of a wide range of materials that exhibit a similar h.c.p./c.c.p. transition.

Kinetics of Metallic Glass Formation by Solid State Reactions

1985 ◽  
Vol 57 ◽  
Author(s):  
K. Samwer ◽  
H Schröder ◽  
M. Moske
Keyword(s):  
Electron Microscopy ◽  
Solid State ◽  
Metallic Glass ◽  
Glass Formation ◽  
Amorphous Layer ◽  
Solid State Reactions ◽  
Diffusion Couples ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Kinetics Of

AbstractMetallic glass formation by solid state reactions has been observed in multilayer Zr-Co diffusion couples. The kinetics of the reaction are limited by the diffusion of the Co-atoms in the growing amorphous layer, at least for longer times, as shown by cross-sectional transmission electron microscopy and resistance measurements. The latter one provides the interdiffusion constant and the activation energy of about 1.1 eV. Deposition of the crystalline layers at 77 K results in an enhanced amorphization process in the first stage of the reaction and gives preliminary answers about the nucleation of the amorphous phase.

Reactive Diffusion between Ti and Cu-9.3Sn-0.3Ti Alloy at Solid-State Temperatures

2011 ◽  
Vol 172-174 ◽  
pp. 470-474
Author(s):  
Masanori Kajihara ◽  
Shingo Nakamura
Keyword(s):  
Solid State ◽  
Diffusion Couple ◽  
Volume Diffusion ◽  
Interface Reaction ◽  
Reactive Diffusion ◽  
Diffusion Couples ◽  
Experimental Conditions

The reactive diffusion between Ti and a bronze was experimentally examined using sandwich diffusion couples consisting of Ti and a Cu-9.3Sn-0.3Ti alloy. The diffusion couples were isothermally annealed at temperatures ofT= 923-1023 K. During annealing, CuTi, (Cu, Sn)4Ti3and (Sn, Cu)5Ti6compounds are formed as layers at the interface in the diffusion couple. The overall growth of the compound layers is controlled by volume diffusion atT= 1023 K but by boundary and volume diffusion atT= 923-973 K. Hence, the interface reaction is not the bottleneck for the growth of the compound layers under the present experimental conditions.

Reaction couples of ceramic thin films prepared by CVD

1988 ◽  
Vol 46 ◽  
pp. 798-799
Author(s):  
D.W. Susnitzky ◽  
S.R. Summerfelt ◽  
C.B. Carter
Keyword(s):  
Thin Film ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Solid State Reactions ◽  
Spatial Distributions ◽  
Diffusion Couples ◽  
Kinetics Studies ◽  
Ceramic Thin Films ◽  
Initial Stage

Solid-state reactions have traditionally been studied in the form of diffusion couples. This ‘bulk’ approach has been modified, for the specific case of the reaction between NiO and Al2O3, by growing NiAl2O4 (spinel) from electron-transparent Al2O3 TEM foils which had been exposed to NiO vapor at 1415°C. This latter ‘thin-film’ approach has been used to characterize the initial stage of spinel formation and to produce clean phase boundaries since further TEM preparation is not required after the reaction is completed. The present study demonstrates that chemical-vapor deposition (CVD) can be used to deposit NiO particles, with controlled size and spatial distributions, onto Al2O3 TEM specimens. Chemical reactions do not occur during the deposition process, since CVD is a relatively low-temperature technique, and thus the NiO-Al2O3 interface can be characterized. Moreover, a series of annealing treatments can be performed on the same sample which allows both Ni0-NiAl2O4 and NiAl2O4-Al2O3 interfaces to be characterized and which therefore makes this technique amenable to kinetics studies of thin-film reactions.

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