Layer-rigidity model and the mechanism for ion-diffusion-controlled kinetics in the bismuth cuprate 2212-to-2223 transformation

Glaucony is a significant green marine facies in the northwestern passive margin of the Guadalquivir Basin (Spain), where glauconite formed authigenically on a sediment-starved continental shelf, with fecal pellets and benthic foraminiferal tests being the main glauconitized substrates. Results from a study using XRD, TGA-DSC, SEM-EDS, and EPMA have revealed that glauconite is remarkably heterogeneous in mineral composition and chemical maturity, even in a single grain, reflecting a complex interaction of micro-environmental factors, substrate influences and post-depositional alterations. In its early stage, the glauconitization process is consistent with the slow precipitation of a Fe-rich smectite phase, most likely intergrade between nontronite and Fe-montmorillonite end-members, which evolved to a regularly interstratified glauconite-smectite (Gl/S). The Fe-smectite-to-Gl/S transformation is interpreted as a diffusion-controlled reaction, involving sufficient Fe availability in pore water and the constant diffusive transport of seawater K+ and Mg2+ ions towards the substrate. The pelletal glauconite is actually a highly evolved Gl/S consisting almost totally of mica layers, with 0.74 ± 0.05 apfu of K+ in the interlayer, while the Gl/S occurring as replacements of foraminiferal tests contains a mean of 7% of expandable layers in the walls and 16% in the chamber fillings, due to rate-limited ion diffusion.

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Ion diffusion-controlled thermally stimulated processes in X-ray irradiated halide crystals

Radiation Effects and Defects in Solids ◽

10.1080/10420150215832 ◽

2002 ◽

Vol 157 (6-12) ◽

pp. 755-759 ◽

Cited By ~ 1

Author(s):

V. Ziraps ◽

V. Graveris ◽

P. Kulis ◽

I. Tale

Keyword(s):

Ion Diffusion ◽

X Ray ◽

Diffusion Controlled

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Experimental Proof for Electrochemical Non-Equilibrium Saturation Currents in Organic Crystals

Zeitschrift für Naturforschung A ◽

10.1515/zna-1974-0115 ◽

1974 ◽

Vol 29 (1) ◽

pp. 131-140

Author(s):

F. Willig

Keyword(s):

Crystal Surface ◽

Redox System ◽

Organic Crystals ◽

Saturation Current ◽

Ion Diffusion ◽

Step Method ◽

Experimental Proof ◽

Diffusion Controlled ◽

First Contact ◽

Non Equilibrium

For the same redox ion, diffusion controlled currents have been compared which were obtained at organic crystals and at a gold electrode. These experiments yield quantitative proof for electrochemical saturation currents in organic crystals with electrolytic contacts. Essential for this result is a modified voltage step method which enables an application of a high voltage simultaneous with the first contact between the crystal surface and the charge injecting electrolyte. The conditions necessary for the occurrence of a saturation current are discussed which also determine the electrochemical nature of this current corresponding to an ideal non-equilibrium between redox system and organic crystal.

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Ion diffusion-controlled processes in fluoride crystals

Radiation Measurements ◽

10.1016/s1350-4487(01)00073-7 ◽

2001 ◽

Vol 33 (5) ◽

pp. 633-636 ◽

Cited By ~ 1

Author(s):

V. Ziraps ◽

P. Kulis ◽

I. Tale ◽

A. Veispals

Keyword(s):

Ion Diffusion ◽

Controlled Processes ◽

Diffusion Controlled ◽

Fluoride Crystals

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A TEM investigation of a hyper-eutectic lead-tin alloy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010010487x ◽

1988 ◽

Vol 46 ◽

pp. 562-563

Author(s):

John A. Sutliff

Keyword(s):

Volume Diffusion ◽

Eutectic Mixture ◽

Precipitation Reaction ◽

Directionally Solidified ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron ◽

Diffusion Controlled ◽

Discontinuous Precipitation Reaction ◽

Controlled Precipitation

Near-eutectic Pb-Sn alloys are important solders used by the electronics industry. In these solders, the eutectic mixture, which solidifies last, is the important microstructural consituent. The orientation relation (OR) between the eutectic phases has previously been determined for directionally solidified (DS) eutectic alloys using x-ray diffraction or electron chanelling techniques. In the present investigation the microstructure of a conventionally cast, hyper-eutectic Pb-Sn alloy was examined by transmission electron microscopy (TEM) and the OR between the eutectic phases was determined by electron diffraction. Precipitates of Sn in Pb were also observed and the OR determined. The same OR was found in both the eutectic and precipitation reacted materials. While the precipitation of Sn in Pb was previously shown to occur by a discontinuous precipitation reaction,3 the present work confirms a recent finding that volume diffusion controlled precipitation can also occur.Samples that are representative of the solder's cast microstructure are difficult to prepare for TEM because the alloy is multiphase and the phases are soft.

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Quantitative surface damage studies by H.R.E.M.

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010015513x ◽

1989 ◽

Vol 47 ◽

pp. 632-633

Author(s):

S. R. Singh ◽

H. J. Fan ◽

L. D. Marks

Keyword(s):

Solar Wind ◽

Quantitative Analysis ◽

Surface Science ◽

Surface Damage ◽

Space Environment ◽

Oxygen Desorption ◽

The Past ◽

Diffusion Controlled ◽

Original Observation ◽

Substantial Interest

Since the original observation that the surfaces of materials undergo radiation damage in the electron microscope similar to that observed by more conventional surface science techniques there has been substantial interest in understanding these phenomena in more detail; for a review see. For instance, surface damage in a microscope mimics damage in the space environment due to the solar wind and electron beam lithographic operations.However, purely qualitative experiments that have been done in the past are inadequate. In addition, many experiments performed in conventional microscopes may be inaccurate. What is needed is careful quantitative analysis including comparisons of the behavior in UHV versus that in a conventional microscope. In this paper we will present results of quantitative analysis which clearly demonstrate that the phenomena of importance are diffusion controlled; more detailed presentations of the data have been published elsewhere.As an illustration of the results, Figure 1 shows a plot of the shrinkage of a single, roughly spherical particle of WO3 versus time (dose) driven by oxygen desorption from the surface.

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