Ionic, electronic and ion-diffusion controlled relaxation processes in CaF2, BaF2and LiBaF3crystals

2001 ◽  
Vol 155 (1-4) ◽  
pp. 431-435
Author(s):  
V. Ziraps ◽  
P. Kulis ◽  
I. Tale ◽  
A. Veispals
Keyword(s):  
Relaxation Processes ◽  
Ion Diffusion ◽  
Diffusion Controlled

Dielectric Relaxation of NaClO4Solutions in Formamide, N-Methylformamide, and N,N-Dimethylformamide

1995 ◽  
Vol 50 (1) ◽  
pp. 65-74 ◽  
Author(s):  
J. Barthel ◽  
K. Bachhuber ◽  
R. Büchner
Keyword(s):  
Average Length ◽  
Ion Pairs ◽  
Liquid Structure ◽  
Acceptor Site ◽  
Relaxation Processes ◽  
Hydrogen Bond Acceptor ◽  
Solvent Interactions ◽  
Structure And Dynamics ◽  
Relaxation Parameters ◽  
Diffusion Controlled

Complex permittivity spectra in the frequency range 0.95 ≤ v/[GHz] ≤ 89 for N,N-dimethylformamide (DMF), N-methylformamide (NMF), formamide (FA) and their solutions of NaClO4 are investigated to study the change of liquid structure and dynamics arising from the availability of one hydrogen-bond acceptor site together with no (DMF), one (NMF), or two (FA) donor sites on the same molecule. Three solvent relaxation processes are observed for NMF and two for FA and DMF. The relaxation parameters are used to determine solvation numbers. They show that ion-solvent interactions lead to a reduction of the average length of the H-bonded NMF chains but have only moderate influence on the FA structure. An additional solute relaxation process in DMF solutions is due to the diffusion-controlled formation and decomposition of solvent-shared ion pairs.

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

2003 ◽  
Vol 158 (8) ◽  
pp. 567-571 ◽  
Author(s):  
V. Ziraps ◽  
V. Graveris ◽  
P. Kulis ◽  
I. Tale
Keyword(s):  
Ion Diffusion ◽  
X Ray ◽  
Diffusion Controlled

scholarly journals Mineralogical and Crystal-Chemical Constraints on the Glauconite-Forming Process in Neogene Sediments of the Lower Guadalquivir Basin (SW Spain)

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 578
Author(s):  
Sandra Fernández-Landero ◽  
Juan Carlos Fernández-Caliani
Keyword(s):  
Early Stage ◽  
Passive Margin ◽  
Ion Diffusion ◽  
Forming Process ◽  
Diffusion Controlled ◽  
Neogene Sediments ◽  
Marine Facies ◽  
Single Grain ◽  
End Members ◽  
Highly Evolved

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.

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

2002 ◽  
Vol 157 (6-12) ◽  
pp. 755-759 ◽  
Author(s):  
V. Ziraps ◽  
V. Graveris ◽  
P. Kulis ◽  
I. Tale
Keyword(s):  
Ion Diffusion ◽  
X Ray ◽  
Diffusion Controlled

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

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.

Ion diffusion-controlled processes in fluoride crystals

2001 ◽  
Vol 33 (5) ◽  
pp. 633-636 ◽  
Author(s):  
V. Ziraps ◽  
P. Kulis ◽  
I. Tale ◽  
A. Veispals
Keyword(s):  
Ion Diffusion ◽  
Controlled Processes ◽  
Diffusion Controlled ◽  
Fluoride Crystals

Dielectric Relaxation Studies of the Fast Lithium-Ion Conductor La2/3-xLi3xTiO3 (x=0.06, 0.11)

2012 ◽  
Vol 457-458 ◽  
pp. 1019-1024
Author(s):  
Wei Guo Wang ◽  
Qian Feng Fang ◽  
Gang Ling Hao
Keyword(s):  
Dielectric Relaxation ◽  
Phonon Frequency ◽  
Lithium Ion ◽  
Relaxation Processes ◽  
Ion Diffusion ◽  
Lithium Ions ◽  
Debye Relaxation ◽  
Exponential Factor ◽  
Relaxation Parameters ◽  
Lithium Ion Diffusion

The diffusion processes of lithium ions in La2/3-xLi3xTiO3 (x=0.06, 0.11) compounds were investigated by dielectric relaxation method. Prominent relaxation dielectric loss peaks, peaks P1 and P2 in La0.56Li0.33TiO3 and peaks P3 and P4 in La0.61Li0.18 TiO3, were observed. From the shift of peak position with frequency, the activation energy of 0.36~0.42 eV and the pre-exponential factor of relaxation time in the order of 10-14 ~ 10-13 s were obtained if one assumes Debye relaxation processes. The activation energies of lithium ion diffusion in La2/3-xLi3xTiO3 compounds and the characteristic vibration frequency for the ionic hopping motion are higher than those measured by 7Li nuclear magnetic resonance (NMR) spectroscopy and that of the typical phonon frequency (about 1013Hz). These values of relaxation parameters strongly suggest the existence of interaction between the relaxation species (here lithium ions or vacancies). Basing on the coupling model, the decoupled relaxation parameters of the dielectric relaxation peaks is: P1 (0.14 eV, 2×10-13 s), P2 (0.25 eV, 1.8×10-13 s), P3 (0.17 eV, 4×10-13 s) and P4 (0.3 eV, 2.7×10-13 s). These decoupled parameters are very close to the NMR measurement results and the reciprocal of the typical phonon frequency. Judging from the relaxation parameter of the peaks and combining with the crystallographic characterization, it is suggested that the P1 (P3) and P2 (P4) peaks are associated with the lithium ion diffusion in the ab planes and between the adjacent ab planes, respectively.

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

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.

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

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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