Single cell microstructure

Figure 13.7 SEM image of the NiO- Ce, d/)2AZr02)o.95(Yb203)o.o502/Lai-xSryMgy03-(Zr02)o.95(Yb203)o.0502 single-cell microstructure. (Reproduced with permission from Ref. [2].)...

A SEM micrograph of the cathode/electrolyte interface and preliminary results on the electrochemical activity of YSZ electrolyte-supported SOFCs containing Ni-YSZ anode and a LSCF-SDC composite cathode are shown in Fig. 14. As it can be seen in Fig. 14(a), the composite film not only has good adhesion to the electrolyte, but also possesses a porous microstructure which is required for the oxidant electrochemical reduction. It indicates that such a composite film can have a good performance as SOFC cathode. By the LSV technique, qualitative information about electrochemical activity of this SOFC was acquired. The power density curves (Fig. 14b) revealed that maximum power densities were 19, 26, 36 and 46 mW/cm2 at 800, 850, 900 and 950 °C. It is possible to compare these first results with literature data and safely state that the LSCF-SDC cathode composite is qualitatively better than other plain standard materials or cathode composites already reported. It should also be mentioned that the result obtained at 800 °C is similar to that reported by Mucdllo et al (Mucdllo et al., 2006) for a SOFC single cell with LSM-YSZ cathode, Ni-YSZ anode and 70 pm... 

Micromachining has been used in the production of electroanalytical structures that have ultralow volumes, typically in the subnanoliter range [10, 11, 13, 14], and are thereby compatible with single cell methods. Broadly speaking, two different methods have been described for producing such picoliter-scale devices embossing (or stamping) of microstructures... 

Figure 9.7 SEM image of the fracture surface of a state-of-the-art single cell with optimized processing and microstructural parameters.

Figure 33.1 Photographs of anode-supported single cell and its microstructure.

More complex staining methods using selective and fluorescent dyes have been used by Phoon et al. (2008), in combination with microscopic analysis. The measurement of cell membrane permeabilization of single cells or protoplasts, using fluorescent dyes, is also possible by means of flow cytometry (Shapiro, 2003), and this technique is gaining increasing interest for the characterization of plant cell microstructures. 

In addition to bilayered electrodes with a functional layer and a support layer, electrodes have also been produced with multilayered or graded structures in which the composition, microstructure, or both are varied either continuously or in a series of steps across the electrode thickness to improve the cell performance compared to that of a single- or bilayered electrode. For example, triple-layer electrodes commonly utilize a functional layer with high surface area and small particle size, a second functional layer (e.g., reference [26]) or diffusion layer with high porosity and coarse structure, and a current collector layer with coarse porosity and only the electronically conductive phase (e.g., reference [27]) to improve the contact with the interconnect. 

Where Jo and S are the current density of the primary beam and the area of the irradiated sample, Z is the wave length, Ohki the structure factor amplitude, Q the volume cell, Z a factor that takes the microstructure of sample into account (Zm - for a mosaic single crystalline film, Zt - for a texture film), t is the sample thickness, dhu the interplanar spacing, a represents the mean angular distribution of the microcrystallites in the film, p is a multiplicity factor (accounts for the number of reflections of coincidence), R is a horizontal coordinate of a particular reflection in DP from textures and (p is the tilt angle of the sample. In the case of polycrystalline films, a local intensity is usually measured and the corresponding relation is ... 

The earliest models of fuel-cell catalyst layers are microscopic, single-pore models, because these models are amenable to analytic solutions. The original models were done for phosphoric-acid fuel cells. In these systems, the catalyst layer contains Teflon-coated pores for gas diffusion, with the rest of the electrode being flooded with the liquid electrolyte. The single-pore models, like all microscopic models, require a somewhat detailed microstructure of the layers. Hence, effective values for such parameters as diffusivity and conductivity are not used, since they involve averaging over the microstructure. 

Some researchers have used approximate microscopic descriptions to develop more rigorous macroscopic constitutive laws. A microstructural model of AC [5] linked the directionality of mechanical stiffness of cartilage to the orientation of its microstructure. The biphasic composite model of [6] uses an isotropic fiber network described by a simple linear-elastic equation. A homogenization method based on a unit cell containing a single fiber and a surrounding matrix was used to predict the variations in AC properties with fiber orientation and fiber-matrix adhesion. A recent model of heart valve mechanics [8] accounts for fiber orientation and predicts a wide range of behavior but does not account for fiber-fiber interactions. 

A 3D liquid flow has been exploited to retain single biological cells for longterm real-time study in a glass chip. With the use of a special microstructure, a zero-speed point (ZSP) can be established as shown in Figure 8.20. The liquid flow in the 2D-plane of the channel dimension is shown in Figure 8.20A-F. The... 

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