Solid interface, characterization materials

SIMS and SNMS are versatile analytical techniques for the compositional characterization of solid surfaces and interfaces in materials research.92-94 As one of the most important applications, both surface analytical techniques allow depth profile analysis (concentration profile as a function of the depth analyzed) to be performed in materials science and the semiconductor industry with excellent depth resolution in the low nm range. For depth profiling in materials science, dynamic SIMS and SNMS using high primary ion beam doses are applied. Both techniques permit the analysis of light elements such as H, , C and N, which are difficult to measure with other analytical techniques. 

The system described in this investigation is polystyrene-14C adsorbed on Graphon carbon black (graphitized Spheron 6) from six solvents comprising a wide spectrum from good to poor solvent power. Well-characterized materials were selected to elucidate the conformation of polymer molecules at the solid/liquid interface. So far two models have been postulated to describe the conformation of the adsorbed polymer molecules at the solid/liquid interface (9, 13, 14, 18, 19, 21, 27). In the first model the polymer assumes a loop or coil structure in which only a fraction of the polymer segments are attached directly at the interface, and in the second model the polymer forms a relatively flat and compressed interfacial layer with many segments attached to the solid substrate. 

Fuel cell researchers deal primarily with interfaces between solid electrolyte materials and solid metallic electrodes. The characterization of electrochemical systems with solid-solid interfaces has become a major issue in the study of fuel cells. It is generally believed that the interface of a solid electrode and solid electrolyte is similar to the electrode/liquid electrolyte interface but more complicated [4],... 

Thermoporometry. Thermoporometry is the calorimetric study of the liquid-solid transformation of a capillary condensate that saturates a porous material such as a membrane. The basic principle involved is the freezing (or melting) point depression as a result of the strong curvature of the liquid-solid interface present in small pores. The thermodynamic basis of this phenomenon has been described by Brun et al. [1973] who introduced thermoporometry as a new pore structure analysis technique. It is capable of characterizing the pore size and shape. Unlike many other methods, this technique gives the actual size of the cavities instead of the size of the openings [Eyraud. 1984]. 

In their efforts to improve and characterize materials, specialists have made use of a large variety of physical techniques that yield precise information about not only bulk properties but also solid surfaces. Such information coupled with the use of computer graphics and simulation can lead to new classes of materials, with novel structures as well as chemical, electrical, magnetic, or mechanical properties. Techniques of materials characterization have undergone a dramatic change in the last few years. Present-day electron microscopes have atomic resolution enabling the study of materials at the atomic level under real conditions (in air, with a liquid interface, in a vacuum, etc.). These are reasons to reconsider the structure morphology-properties relationships. 

This book, based on a series of summer schools held in Lyon every year since 2007, aims to provide students, engineers, and confirmed researchers alike with an introduction to the major thermal analysis techniques used to characterize solid materials and investigate their surface reactivity, including both physical and chemical processes occurring at gas-solid or liquid-solid interfaces. The main topics covered include ... 

In recent years, advances in experimental capabilities have fueled a great deal of activity in the study of the electrified solid-liquid interface. This has been the subject of a recent workshop and review article [145] discussing structural characterization, interfacial dynamics and electrode materials. The field of surface chemistry has also received significant attention due to many surface-sensitive means to interrogate the molecular processes occurring at the electrode surface. Reviews by Hubbard [146, 147] and others [148] detail the progress. In this and the following section, we present only a brief summary of selected aspects of this field. 

This volume contains 50 articles describing analytical techniques for the characterization of solid materials, with emphasis on surfaces, interfaces, thin films, and microanalytical approaches. It is part of the Materials Characterization Series, copublished by Butterworth-Heinemann and Manning. This volume can serve as a stand-alone reference as well as a companion to the other volumes in the Series which deal with individual materials classes. Though authored by professional characterization experts the articles are written to be easily accessible to the materials user, the process engineer, the manager, the student—in short to all those who are not (and probably don t intend to be) experts but who need to understand the potential applications of the techniques to materials problems. Too often, technique descriptions are written for the technique specialist. 

While characterization of the electrode prior to use is a prerequisite for a reliable correlation between electrochemical behaviour and material properties, the understanding of electrochemical reaction mechanisms requires the analysis of the electrode surface during or after a controlled electrochemical experiment. Due to the ex situ character of photoelectron spectroscopy, this technique can only be applied to the emersed electrode, after the electrochemical experiment. The fact that ex situ measurements after emersion of the electrode are meaningful and still reflect the situation at the solid liquid interface has been discussed in Section 2.7. 

Especially for inorganic functional materials, it is evident that for the majority of cases the situation is completely different. Even though today a full range of analytical methods is at hand, it is impossible to fully characterize a solid-state material. This does not even take into account that catalysis (with the help of solid-state catalysts) is an interface phenomenon and traces of impurities very... 

One of the most common ways to characterize the hydrophobicity (or hydrophilicity) of a material is through measurement of the contact angle, which is the angle between the liquid-gas interface and the solid surface measured at the triple point at which all three phases interconnect. The two most popular techniques to measure contact angles for diffusion layers are the sessile drop method and the capillary rise method (or Wihelmy method) [9,192]. 

In addition to the criticisms from Anderman, a further challenge to the application of SPEs comes from their interfacial contact with the electrode materials, which presents a far more severe problem to the ion transport than the bulk ion conduction does. In liquid electrolytes, the electrodes are well wetted and soaked, so that the electrode/electrolyte interface is well extended into the porosity structure of the electrode hence, the ion path is little affected by the tortuosity of the electrode materials. However, the solid nature of the polymer would make it impossible to fill these voids with SPEs that would have been accessible to the liquid electrolytes, even if the polymer film is cast on the electrode surface from a solution. Hence, the actual area of the interface could be close to the geometric area of the electrode, that is, only a fraction of the actual surface area. The high interfacial impedance frequently encountered in the electrochemical characterization of SPEs should originate at least partially from this reduced surface contact between electrode and electrolyte. Since the porous structure is present in both electrodes in a lithium ion cell, the effect of interfacial impedances associated with SPEs would become more pronounced as compared with the case of lithium cells in which only the cathode material is porous. 

The relevance of LSC data to reverse osmosis stems from the physicochemical basis (adsorption equilibrium considerations) of liquid-solid chromatography (52), and the principle that the solute-solvent-membrane material (column material) Interactions governing the relative retention times of solutes in LSC are analogous to the interactions prevailing at the membrane-solution Interface under reverse osmosis conditions. The work already reported in several papers on the subject (53-58) indicate that the foregoing principle is valid, and hence LSC data offer an appropriate means of characterizing interfacial properties of membrane materials, and understanding solute separations in reverse osmosis. 

In nonporous membranes, diffusion occurs as it would in any other nonporous solid. However, the molecular species must first dissolve into the membrane material. This step can oftentimes be slower than the diffusion, such that it is the rate-limiting step in the process. As a result, membranes are not characterized solely in terms of diffusion coefficients, but in terms of how effective they are in promoting or limiting both solubilization and diffusion of certain molecular species or solutes. When the solute dissolves in the membrane material, there is usually a concentration discontinuity at the interface between the membrane and the surrounding medium (see Figure 4.55). The equilibrium ratio of the solute concentration in one medium, c, to the solute concentration in the surrounding medium, C2, is called the partition coefficient, K12, and can be expressed in terms of either side of the membrane. For the water-membrane-water example illustrated in Figure 4.55,... 

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