Films phases

Examples of XRD Characterization of Thin Films Phase Identification... 

Budkowski, A. Interfacial Phenomena in Thin Polymer Films Phase Coexistence and Segregation, Vol. 148, pp. 1-112. 

As in Section II,B,l,b, the gas-phase Peclet number is assumed to be infinite, and the dimensionless group M is easily evaluated. The interfacial area a can be calculated with a knowledge of the holdup of the film phase... 

Chemical solution deposition (CSD) procedures have been widely used for the production of both amorphous and crystalline thin films for more than 20 years.1 Both colloidal (particulate) and polymeric-based processes have been developed. Numerous advances have been demonstrated in understanding solution chemistry, film formation behavior, and for crystalline films, phase transformation mechanisms during thermal processing. Several excellent review articles regarding CSD have been published, and the reader is referred to Refs. 5-12 for additional information on the topic. Recently, modeling of phase transformation behavior for control of thin-film microstructure has also been considered, as manipulation of film orientation and microstructure for various applications has grown in interest.13-15... 

As described in Sect. 2.1.2, block copolymer thin film phase behavior can be controlled by the surface/interface energies as well as the interplay between the film thickness t and polymer natural period Lo. Depending on the nature of the surface interactions, block copolymer thin films can be separated into two general categories [14,41] ... 

Let us examine the instability oi strained thin films. In Fig. 3, thin films of30 ML are coherently bonded to the hard substrates. The film phase has a misfit strain, e = 0.01, relative to the substrate phase, and the periodic length is equal to 200 a. The three interface energies are identical to each other = yiv = y = Y Both phases are elastically isotropic, but the shear modulus of the substrate is twice that of the film (p = 2p). On the left-hand side, an infinite-torque condition is imposed to the substrate-vapor and film-substrate interfaces, whereas torque terms are equal to zero on the right. In the absence of the coherency strain, these films are stable as their thickness is well over 16 ML. With a coherency strain, surface undulations induced by thermal fluctuations become growing waves. By the time of 2M, six waves are definitely seen to have established, and these numbers are in agreement with the continuum linear elasticity prediction [16]. 

Figure 3. Moiphological evolution of strained thin-films under the infinite- and zero-torque conditions. Thin films of 30 ML and are coherently bonded to the hard substrates whose shear modulus is twice that of the film (q =2q). The film phase has amisfit strain, e= 0.01, relative to the substrate phase.

A similar technique can be used to study the rheological properties of liquid films. Figure 4 shows the formation of a W/O/W emulsion film with two, identical aqueous phases (such as in water-in-oil emulsions) at the tip of the capillary. A pre-requisite of the experiment is that the surface of the capillary must be well wetted by the film phase, i.e., it should be hydrophobic in this case. First, an aqueous drop is formed inside the oil (film liquid) and the aqueous phase is in the bottom of the cuvette. Then, the level of the aqueous phase is slowly increased. As the oil/water interface passes the drop, a cap shaped oil film, bordered by a circular meniscus, covers the drop. This film can be studied in equilibrium and in dynamic conditions, similar to the single interfaces (See above). The technique can be used to study films from oil or aqueous phase which can be sandwiched between identical or different liquid or gas phases. 

When two emulsion drops or foam bubbles approach each other, they hydrodynamically interact which generally results in the formation of a dimple [10,11]. After the dimple moves out, a thick lamella with parallel interfaces forms. If the continuous phase (i.e., the film phase) contains only surface active components at relatively low concentrations (not more than a few times their critical micellar concentration), the thick lamella thins on continually (see Fig. 6, left side). During continuous thinning, the film generally reaches a critical thickness where it either ruptures or black spots appear in it and then, by the expansion of these black spots, it transforms into a very thin film, which is either a common black (10-30 nm) or a Newton black film (5-10 nm). The thickness of the common black film depends on the capillary pressure and salt concentration [8]. This film drainage mechanism has been studied by several researchers [8,10-12] and it has been found that the classical DLVO theory of dispersion stability [13,14] can be qualitatively applied to it by taking into account the electrostatic, van der Waals and steric interactions between the film interfaces [8]. 

Due to the chemical conversion in the liquid film, the molar fluxes at the interface and at the boundary between the film and the bulk of the phase differ. The system of equations is completed by the conservation equations for the mass and energy fluxes at the phase interface and the necessary linking conditions between the bulk and film phases (see Refs. 57, 59, and 84). 

Generally all these considerations are also valid for the second fluid film phase, provided that reactions occur there (135). Both analytical and numerical solutions of the coupled diffusion-reaction film problem are analyzed at full length in Ref. 167 their particular applications are considered in Section 3. 

Fig. 2.3. Five orders of reflection in a thin film results also show the presence of the two most X-ray diffraction scan, indicating the high level common polymorphs of pentacene, the bulk-of crystallinity often present in pentacene thin like phase and the thin-film phase [25]. films deposited on different dielectrics. These...

D. Gundlach, Y. Lin, T. Jackson, S. Nelson, D. Schlom, IEEE Electr. Dev. Lett., 1997, 18, 87. [The term fhin-film phase, was not used in this publication, but was adopted later to refer to the 15 A d-spadng observed in some, often higher mobility pentacene layers.]... 

Danev R, Nagayama K (2006) Applicability of thin film phase plates in biological electron microscopy. Biophysics 2 35-43... 

Interfacial Phenomena in Thin Polymer Films Phase Coexistence and Segregation... 

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