Transmission electron microscopy grain measurements

Transmission Electron Microscopy (TEM) has been used to characterize aluminum thin films thermally evaporated (vacuum around 10 4 Torr) on Polyethyleneterephtalate (Mylar) and to correlate the crystallographic structure of the system Al/Mylar and the adhesion of the aluminum films. The adhesion of these films has been measured by a Peel test technique. For the polymer, an amorphous layer (t=12 nm) followed by a crystalline film have been observed on a Corona treated film and the opposite configuration has been found on a bi-axially stretched film. Some spherical precipitation ana interdiffusion zones have also be observed in the Mylar for the films which have the lower coefficient of adhesion (100 g/inch). The main conclusion is the augmentation of the adhesion of the aluminum film as the size of the grains decreases and/or as the microroughness of the Al/Mylar interface increases. 

The non-porous SiO powder of Balzers (nominal purity 99.9% grain size 0.2 to 0.7 mm) was studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM) in the as-received state as well as after heating to about 1300 °C in high vacuum for 1 h to ensure that the material exhibits the expected behavior. Figure 19.2 shows the results of XRD measurements obtained with the copper Ka line of a PHILIPS X-ray diffractometer. 

Phase identification may be accomplished via XRD. FTIR is recommended as a complementary technique because it allows identification of phase amounts and structures not readily detectable with XRD (Ducheyne, 1990). Grain sizes may be determined through either optical microscopy, SEM, or transmission electron microscopy (TEM), depending on the order of the grain size. Additionally, TEM is useful to characterize second phases, crystal structure, and lattice imperfections. Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) may also be utilized to determine surface and interfacial compositions. Chemical stability and surface activity may be analyzed via XPS and measurements of ionic fluxes and zeta potentials. It is assumed that two different pathways of activity exist solution and cell-mediated (Jarcho, 1981). 

Results are often converted to an equivalent monolayer coverage for direct comparison with field emission gun scanning transmission electron microscopy (FEGSTEM) EDX measurements of grain boundary segregation. The calculation is straightforward for binary systems, but the complexity rapidly increases as the number of elements increases. The equivalent monolayer coverages (O) for P and C in Fe are summarised in Table 92 ... 

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