Microstructure and intergranular diffusion in exchange-coupled Sm–Co/Fe nanocomposites

2010 ◽  
Vol 97 (3) ◽  
pp. 032506 ◽  
Author(s):  
Ying Zhang ◽  
M. J. Kramer ◽  
Chuanbing Rong ◽  
J. Ping Liu
Keyword(s):  
Intergranular Diffusion

scholarly journals Structural, Electrical, Dielectric, and Magnetic Properties of Cd2+ Substituted Nickel Ferrite Nanoparticles

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
B. H. Devmunde ◽  
A. V. Raut ◽  
S. D. Birajdar ◽  
S. J. Shukla ◽  
D. R. Shengule ◽  
...  
Keyword(s):  
Ac Susceptibility ◽  
Sol Gel ◽  
Interfacial Polarization ◽  
Ferrite Nanoparticles ◽  
Scanning Electron Micrographs ◽  
X Ray Diffraction ◽  
Nickel Ferrite Nanoparticles ◽  
Phase Spinel ◽  
Intergranular Diffusion ◽  
Fe Ions

In the present investigation structural, electric, magnetic, and frequency dependent dielectric properties of Ni1-xCdxFe2O4 ferrite nanoparticles (NPs) (where x=0.2, 0.4, 0.6, and 0.8) prepared by sol-gel autocombustion method were studied. The crystallite size (t) (46.89~58.40 nm) was estimated from X-ray diffraction data with the postconfirmation of single phase spinel structure. Spherical shaped, fused grain nature with intergranular diffusion in Ni1-xCdxFe2O4 NPs was observed in scanning electron micrographs. The value of loss tangent (tan⁡δ) decreases exponentially with an increasing frequency indicating normal Maxwell-Wagner type dielectric dispersion due to interfacial polarization. Decreasing values of Curie temperature (TC) from 860°C to 566°C with increasing Cd2+ content x in Ni1-xCdxFe2O4 NPs were determined from AC-Susceptibility. Activation energy ΔE ranges within 0.03~0.15 eV. Decreasing magnetic saturation Ms, coercivity Hc, and magneton number nB values show the effect on nonmagnetic Cd2+ ions over magnetic Ni2+ and Fe ions.

Relations between intergranular diffusion and structure: A molecular dynamics study

1984 ◽  
Vol 144 (1) ◽  
pp. 67-76 ◽  
Author(s):  
M. Guillope ◽  
G. Ciccotti ◽  
V. Pontikis
Keyword(s):  
Molecular Dynamics ◽  
Intergranular Diffusion

Measurement of Intergranular Diffusion in a Silicate System: Iron in Forsterite

Nature ◽  
1959 ◽  
Vol 184 (4688) ◽  
pp. BA54-BA56 ◽  
Author(s):  
JOHN J. NAUGHTON ◽  
YASUO FUJIKAWA
Keyword(s):  
Silicate System ◽  
Intergranular Diffusion

The catalysis of mineral reactions by water and restrictions on the presence of aqueous fluid during metamorphism

1986 ◽  
Vol 50 (357) ◽  
pp. 399-415 ◽  
Author(s):  
David C. Rubie
Keyword(s):  
Grain Boundaries ◽  
Fluid Phase ◽  
Aqueous Fluid ◽  
Western Alps ◽  
Metamorphic Rocks ◽  
Time Interval ◽  
Basement Rocks ◽  
Mineral Assemblages ◽  
Intergranular Diffusion ◽  
Adula Nappe

AbstractThe problems of characterizing inter-granular regions and of estimating rates of intergranular diffusion in metamorphic rocks are discussed. Inter-granular regions can be anhydrous, hydrated but under-saturated with H2O, or saturated with H2O, but only in the latter case can a free aqueous fluid phase be present. Estimates of intergranular diffusion coefficients (DIGR) at 550°C derived from a variety of published experimental work, vary from ∼ 10−8 m2 s−1 for diffusion of species through an intergranular fluid film to ⩽ 4 × 10−24 m2 s−1 for diffusion of SiO2 or O in anhydrous grain boundaries in quartzite. Estimates of DIGR for hydrated grain boundaries vary from ∼ 10−13 m2 s−1 to ∼ 10−21 m2 s−1; the concentration of H2O in the grain boundaries and the identity of the diffusing species (generally unknown) may be important controlling factors, and there exists the possibility of a spectrum of values between these two extremes.Using available kinetic data it is shown that a free aqueous fluid could never have been present in parts of the basement terrane of the Sesia Zone (Western Alps) during uplift from the eclogite facies, except possibly late in the cooling history. The breakdown of sodic pyroxene + quartz occurred in response to the localized infiltration of catalytic aqueous fluid, possibly over a time interval as short as 6–6000 a, and possibly under conditions remote from equilibrium. H2O-present conditions during a dehydration reaction in metapelites of the Adula nappe (central Alps) could also have been of short duration. These examples are consistent with a model in which basement rocks at deep crustal levels are dry for long periods of time and in which the development of equilibrium mineral assemblages and microstructures generally occurs over relatively short periods of time under transitory fluid-present conditions (caused by devolatilization and/or infiltration).

Competitive diffusion-controlled growth of porphyroblasts

1991 ◽  
Vol 55 (380) ◽  
pp. 317-330 ◽  
Author(s):  
William D. Carlson
Keyword(s):  
Crystal Size ◽  
Quantitative Information ◽  
Chemical Inhomogeneity ◽  
Controlled Growth ◽  
Size Distributions ◽  
Compositional Zoning ◽  
Frequency Distributions ◽  
Diffusion Controlled ◽  
Intergranular Diffusion ◽  
Kinetics Of

AbstractIn a diffusion-controlled process of nucleation and growth, adjacent porphyroblasts compete with one another for nutrients. When the effects of this competition are evaluated quantitatively for garnet porphyroblasts in pelitic rocks from the Picuris Range of New Mexico (U.S.A.), significant correlations arise between crystal sizes and the volumes of the domains from which the crystals drew their nutrients. These correlations strengthen the conclusion drawn from earlier work on spatial dispositions, zoning patterns, and crystal size distributions that the kinetics of intergranular diffusion governed the crystallisation of these porphyroblasts.Computer simulations indicate that competition for nutrients during diffusion-controlled growth may have small but detectable effects on crystal size frequency distributions. Diffusional competition therefore introduces relatively minor inaccuracies into attempts to extract quantitative information on crystallisation processes from size distributions using models for the growth of isolated porphyroblasts. In contrast, the effects of diffusional competition on patterns of compositional zoning may be substantial, especially for porphyroblasts in rocks for which chemical inhomogeneity of the precursor leads to strongly clustered spatial dispositions. In such rocks, clustering may alter the patterns of compositional zoning in ways that obscure evidence for diffusion-controlled growth.

Intergranular diffusion of platinum by bismuth

1986 ◽  
Vol 5 (8) ◽  
pp. 829-831
Author(s):  
P. J. Picone ◽  
J. G. L. Terlet
Keyword(s):  
Intergranular Diffusion

Intergranular diffusion and embrittlement of a Ni–16Mo–7Cr alloy in Te vapor environment

2015 ◽  
Vol 467 ◽  
pp. 341-348 ◽  
Author(s):  
Hongwei Cheng ◽  
Zhijun Li ◽  
Bin Leng ◽  
Wenzhu Zhang ◽  
Fenfen Han ◽  
...  
Keyword(s):  
Intergranular Diffusion

Relations between intergranular diffusion and structure: A molecular dynamics study

1984 ◽  
Vol 144 (1) ◽  
pp. A328
Author(s):  
M. Guillope ◽  
G. Ciccotti ◽  
V. Pontikis
Keyword(s):  
Molecular Dynamics ◽  
Intergranular Diffusion
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