Texture determination

Barometric chemisorption. Chemisorption on catalysts is measured routinely by the barometric method. The equipment is very similar to that commonly used in texture determination by physical adsorption (see Section 3.6.2), except that for chemisorption measurements facilities for pretreatment of the samples should be present. In particular for metal catalysts often the catalyst is received in a partly or fully oxidized form and, as a consequence, reduction is required when one wants to measure the amount of active sites. Moreover, during storage adsorption of various molecules might occur and evacuation is... 

The atomic structure of a heterogeneous catalyst determines its chemical and phase properties, but texture determines a wide range of additional features that dictate such characteristics as adsorption and capillarity, permeability, mechanical strength, heat and electrical conductivity, etc. For example, the apparent catalytic activity,. of a grain, taking into account diffusion of reagents, depends on the interrelation between the rates of reaction and diffusion, and the latter is determined by a porous structure. 

It is seen from the discussion above that Cu is electrodeposited in vias and trenches on a bilayer a barrier metaVCu seed layer. When the barrier layer is composed of two layers (e.g., TiN/Ti), Cu is electrodeposited as a trilayer a barrier bilayer/Cu seed layer. This type of underlayer for electrodeposition of Cu raises a series of interesting theoretical and practical questions of considerable significance regarding the reliability of interconnects on chips. In Section 19.1 we have noted that interconnect reliability depends on the microstructural attributes of electrodeposited Cu (for Cu-based interconnects). These microstractural attributes, such as grain size, grain size distribution, and texture, determine the mechanical and physical properties of the thin films. Thus, one basic question in the foregoing series of questions is the problem of the influence of the underlayer barrier metal on the microstructure of the Cu seed layer. The second question is the influence of the microstructure of the Cu seed layer on the structure... 

H. P. King andL. E. Alexander, X-Ray Diffraction Procedures , 2nd edition, John Whey Sons, New York, 1974, A very comprehensive treatment. X-ray powder methods including linebroadening analysis, texture determination, stress measurement and studies of amorphous materials. 

Vol. III. Physical and Chemical Tables (1962). Includes data on characteristic wavelengths, absorption coefficients, atomic scattering factors, Compton scattering, etc. Also treatments of intensity measurements, texture determination, particle size broadening, small angle scattering, and radiation hazards. 

G.44 Shuji Taira, ed. X-Ray Studies on Mechanical Behavior of Materials (Kyoto Society of Materials Science, Japan, 1974). A collaborative account by twenty-seven Japanese investigators of x-ray studies of phenomena affecting the strength of materials. X-ray stress measurements are described, as well as texture determination, line-broadening studies, microbeam methods, pseudo-Kossel patterns, small angle scattering, and x-ray topography. 

Concerning interest in texture analysis, the community of diffractionists can be roughly divided in two categories. For the first category the goal is a quantitative texture analysis. The texture can have important effects on some physical properties of manufactured materials. Consequently, the texture determination is a necessary step in material characterization. 

Texture determination textural properties of starch gels were determined using a TA-XT2 texture analyzer (Stable Micro Systems, Scarsdale, NY, USA). A textural profile analysis (TPA) test was performed using a 0.50 S sphere (0.5 in. diameter) probe on gels equilibrated to room temperature to measure hardness and adhesiveness. Only the samples with starch concentration of 10% (% s/w) could be analyzed because they had a texture that fell within the detectability limit of the instrument. At least ten replicates were rim for each gel. 

On the macroscopic level reaction and catalyst systems have been defined and process considerations determine the role of further catalyst development. Catalyst research has contributed to the development of texture determination techniques... 

Qng, M. H., and J. H. V. Blanshard. 1995. Texture determinants in cooked parboiled rice. I. Rice starch amylose and the fine structure of amylop>ectin. Journal of Cereal Science 21 251-260. 

The using of x ray beams in measuring the diffracted intensity given by a specimen under various geometrical conditions is exposed as the nowadays more useful method for texture determination in materials. 

For the reduction process of magnetite a core-and-shell mechanism was proposed and tested in detail (8). Thereafter, a catalyst particle is continuously converted into a porous shell of metallic iron topotactically formed on a nonre-duced core by a propagating reaction front. It was, however, found that this simple concept has to be modified and that the reduction process is, in fact, rather complex in the presence of the promoters (9). In particular, it was concluded that the resulting ammonia-iron consists of Fe particles with a preferred (111) texture determined by the preferential migration of iron ions separated from each other by particles of the structural promoter. 

Cropping. All these characteristics of the different soil textures determine which crops can be grown successfully arrd their yield potential. 

The volatilization from soil is more complicated because of the numerous additional mechanisms that are present in the soil, as shown in Figure 7.1. To be volatilized from soil, the herbicide may be lost directly from its solid form to its gaseous form, or it may be released from being adsorbed to soil particles into the soil solution, diffuse into the soil air, and move to the surface to be dispersed into the turbulent air flow above the soil. How close this turbulent region is to the surface depends on the condition of the soil surface. Cultivation practice and soil texture determine the number and size of the clods on the surface, and thus the relative smoothness will determine the evenness of the application of the herbicide and influence the air flow and microclimate at the air-soil interface. The air within the soil is virtually static above this, there is an area of laminar... 

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