Interfacial imperfection

Microscopic imperfections are generally classified as either point, line, or interfacial imperfections. 

Interfacial imperfections are larger than line defects and occur over a two-... 

Interfacial imperfections are larger than line imperfections and occur over a two dimensional area. Interfacial imperfections exist at free surfaces, domain boundaries, grain boundaries, or interphase boundaries. 

Yang, S., Yu, S., Kyoung, W., Han, D. S., and Cho, M. Multiscale modeling of size-dependent elastic properties of carbon nanotube/polymer nanocomposites with interfacial imperfections. Polymer, 53, 623-633 (2012). 

The voltammograms at the microhole-supported ITIES were analyzed using the Tomes criterion [34], which predicts ii3/4 — iii/4l = 56.4/n mV (where n is the number of electrons transferred and E- i and 1/4 refer to the three-quarter and one-quarter potentials, respectively) for a reversible ET reaction. An attempt was made to use the deviations from the reversible behavior to estimate kinetic parameters using the method previously developed for UMEs [21,27]. However, the shape of measured voltammograms was imperfect, and the slope of the semilogarithmic plot observed was much lower than expected from the theory. It was concluded that voltammetry at micro-ITIES is not suitable for ET kinetic measurements because of insufficient accuracy and repeatability [16]. Those experiments may have been affected by reactions involving the supporting electrolytes, ion transfers, and interfacial precipitation. It is also possible that the data was at variance with the Butler-Volmer model because the overall reaction rate was only weakly potential-dependent [35] and/or limited by the precursor complex formation at the interface [33b]. 

Note 4 The degree of crystallinity can be determined by several experimental techniques among the most commonly used are (i) X-ray diffraction, (ii) calorimetry, (iii) density measurements, and (iv) infrared spectroscopy (IR). Imperfections in crystals are not easily distinguished from the amorphous phase. Also, the various techniques may be affected to different extents by imperfections and interfacial effects. Flence, some disagreement among the results of quantitative measurements of crystallinity by different methods is frequently encountered. 

On drawing current from a passivated lithium anode, polarization may be at first severe, but the voltage recovers fairly rapidly (Fig. 4.6). Initially, charge transfer at the anode is limited by lithium ion transport through a thin or imperfect section of the interfacial film. This process progressively... 

It is assumed that deeply trapped holes, h+ff, are chemically equivalent to surface-bound hydroxyl radicals. Weakly trapped holes, on the other hand, that are readily detrapped apparently posses an electrochemical potential close to that of free holes and can therefore be considered to be chemically similar to the latter. Their shallow traps are probably created by surface imperfections of the semiconductor nanocrystals. From these traps the charge carriers recombine or they are transferred by interfacial charge transfer to suitable electron acceptors or donors adsorbed at the surface of the semiconductor. 

These systems are imperfect models for molecular recognition, since both the potential functions and energy distributions that describe the interactions in MESA are different from those at the molecular level. Moreover, the encounter frequencies between objects in MESA (10 3—10-2 s-1) are much smaller than those between molecules (102-103 s, for micromolar concentrations). Despite these differences, our model manages to exhibit the salient characteristics of molecular recognition assembly depends on the shapes and interfacial properties of the faces that recognize one another. 

The gap between the predictions and experimental results arises from imperfect dispersion of carbon nanotubes and poor load transfer from the matrix to the nanotubes. Even modest nanotube agglomeration impacts the diameter and length distributions of the nanofillers and overall is likely to decrease the aspect ratio. In addition, nanotube agglomeration reduces the modulus of the nanofillers relative to that of isolated nanotubes because there are only weak dispersive forces between the nanotubes. Schadler et al. (71) and Ajayan et al. (72) concluded from Raman spectra that slippage occurs between the shells of MWNTs and within SWNT ropes and may limit stress transfer in nanotube/polymer composites. Thus, good dispersion of CNTs and strong interfacial interactions between CNTs and PU chains contribute to the dramatic improvement of the mechanical properties of the... 

The influence of this imbalance of interactions extends some distance into the material from the surface. The real surface of a material is not an absolutely flat and smooth array of atoms like that found on the surface of a single crystal, and a surface might contain many imperfections, voids, and boundary domains between different phases. The materials in this region, whose properties differ from those of the bulk phase, constitute the surface state. In this context, a surface is a two-dimensional plane and a surface state is a three-dimensional phase. Interfacial phenomena should be interpreted by examining the interaction of two surface states that contact at an interface. 

Surface atoms, crystal imperfections and adsorbed molecules can give rise to localized energy levels located in the band gap. These so-called surface states play an important role as mediators of interfacial electron transfer. The surface states may or may not be occupied by an electron the surface-localized electrons give a contribution, as, to the surface charge ... 

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