Particulate thin films

L. Gunther, W. Peukert, The relevance of interactions in nanoparticle systems—application to particulate thin films, Part. Part. Syst. Charact. 19 (2002) 312. 

We are now prepared to discuss the evolving field of structure formation in drying particulate (thin) films. SoHd-Hquid separation is a very important unit operation where the fluid flow may be directed either normal to the filter medium or, in case of cross-flow filtration, parallel to it. The filter cake... 

We now discuss the integration of particles in devices by choosing two examples, i.e., particulate thin films (case 1) and 3D printing (case 2). 

In the case of Co—Cr having perpendicular anisotropy there is, in principle, a competition between the uniaxial anisotropy of a hexagonal stmcture and the demagnetizing energy of the thin film. In the case of magnetically separated Co—Cr columns (particulate morphology) then also the shape anisotropy contributes to the perpendicular anisotropy. 

Either particulate sol or polymeric sol has been used for thin film coatings. The polymeric sol was fabricated by partial hydrolysis of corresponding metal alkoxide. If the rate of hydrolysis or condensation is very fast, then some kinds of organic acids, beta-dicarbonyls, and alkanolamines have been used as chelating agent in sol-gel processes to control the extent and direction of the hydrolysis-condensation reaction by forming a strong complex with alkoxide. [2]. 

Recent considerations of metal UPD on semiconductor surfaces suggest that light-assisted processes gain much significance in the relevant technology. The use of photoinduced UPD as an approach for the preparation of compounds and composite semiconductors either in thin films (layered structures) or in particulate suspensions is a challenging issue that will be outlined promptly. 

Fig. 1. Typical structures of storage media. Top a particulate disk. Center a thin-film disk. Bottom ...

Electrochemical science and technology have played an important role in all aspects of the new technology of the thin-film disk, which is capable of higher storage density than the particulate disk. The first disks, at the beginning of the technology more than... 

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... 

Mann, E. K. Heinrich, L. Schaaf, P.,Validity of the uniform thin film approximation for the optical analysis of particulate films, Langmuir 1997, 13,4906 4909... 

A thin film of oil-like material was visible after 28 d on the exterior surfaces of the SPMD membrane. Analysis of this film indicated that the triolein impurities, oleic acid and methyl oleate, were the major constituents. This external lipid film (Petty et al., 1993) appeared to contain imbibed particulates. Although the film was removed from the SPMDs by solvent rinsing and analyzed separately, some lipid-mediated desorption of particle-associated PCBs and subsequent diffusion into the SPMD may have occurred prior to solvent-removal of the film. This observation suggests the potential for SPMD concentrations to reflect both vapor phase concentrations and to a lesser extent, lipid-extracted particulate-associated residues (see Section 3.9.2.). Unfortunately, concentrations of more chlorinated congeners in particulates collected on GFFs from the NIOSH method were often below quantitation limits, because only a small volume of air was sampled (1 m ) using this active method. 

Visual detection of surface layers on cathodes using microscopy techniques such as SFM seems to be supportive of the existence of LiF as a particulate-type deposition.The current sensing atomic force microscope (CSAFM) technique was used by McLarnon and co-workers to observe the thin-film spinel cathode surface, and a thin, electronically insulating surface layer was detected when the electrode was exposed to either DMC or the mixture FC/DMC. The experiments were carried out at an elevated temperature (70 °C) to simulate the poor storage performance of manganese spinel-based cathodes, and degradation of the cathode in the form of disproportionation and Mn + dissolution was ob-served. °° This confirms the previous report by Taras-con and co-workers that the Mn + dissolution is acid-induced and the electrolyte solute (LiPFe) is mainly responsible. 

In the atmosphere, suspended aqueous solutions are present in the form of aerosols, clouds, fogs, and rain. However, these have different liquid water contents (i.e., grams of H20(l) per cubic meter of air). As discussed in detail in Chapter 9, fine particles (< 2-yxm diameter) emitted directly into the air or formed by chemical reactions can remain suspended for long periods of time. Many of these particles contain water, either in the form of dilute aqueous solutions or as thin films covering an insoluble core as much as 50% of the mass may be liquid water. Since the total particulate mass in this size range per cubic meter of air can be as high as 10 4 g m-3 or more, the liquid water content due to these small particles is also of this order of magnitude. 

SOL-GEL TECHNOLOGY. The goal of sol-gel technology is lo use low temperature chemical processes to produce net-shape, net-surfacc objects, films, fibers, particulates, or composites that can be used commercially after a minimum of additional processing steps. See also Thin Films. Sol-gel processing can provide control of microstructures in the nanometer size range, i.e 1-100 nm (0.001-0.1 pm), which approaches the molecular level These materials often have unique physical and chemical characteristics. See also Nanotechnology (Molecular). 

---