Thin films preparation from solution

The Hall voltage was measured in the thin film heat-treated at 700°C. The increase and decrease of mobility and carrier density corresponded to that of resistivity. The resistivity of the thin films prepared under the same condition has lowered in the order, solution D, solution C, solution B and solution A. The thin film prepared from solution D showed large carrier density (22.6 x 10 cm" ) andmobility (1.49 cm s ) when heat-treated in air. 

Figure 27.11 SEM surface images of Ca-modifled PbTi03 thin films prepared from solutions containing (a) a short carbon chain carboxylate compound of calcium (calcium acetate) and (b) a long carbon chain compound of calcium (calcium acetylacetonate). (c) IR analysis of the powder resulting after...

Experimental agents were evaluated for fluorescent properties using thin films prepared from 2 wt% chloroform solutions and results summarized in Table 1. 

S. Deki, Y. Aoi, O. Hiroi, and A. Kajinami, Titanium (IV) Oxide thin films prepared from aqueous solution, Chem. Letters 433-434 (1996). 

In the following, results obtained for thin films prepared from unsubstituted oligothiophenes, are reviewed in detail. The influence of substituents is briefly mentioned where it is important. Results of oligothiophenes in solution and on polythiophenes are... 

Fig. 9 Scanning electron micrograph of iron oxide thin films prepared from (a) ultrasonic spray pyrolysis and (b) conventional spray pyrolysis of Fe(acetylacetonate)3 solutions. (Reproduced with permission from [71])...

Very recent studies have been devoted to the preparation and characterization of smooth lignin surfaces of extremely thin films spun from solutions [72]. The interaction of these surfaces with a cellulose sphere has been quantified [73] and the corresponding forces found to behave according to the DLVO theory. 

In industry, time is at premium so the emphasis is always to carry out the analysis in the most efficient manner possible. In practice, this means that the analyst employs the sampling method that requires the least possible sample preparation. Historically, the great majority of liquid samples were run as thin Aims between infrared transparent plates (usually KBr) or in fixed pathlength cells. Similarly, most solid samples were run as KBr discs, as mulls or as a thin film deposited from solution onto a suitable substrate. Polymers were usually hot-pressed to make a self-supporting film, with a thickness typically between 0.020 and 1.0 mm the former being used for the identification of a bulk material and the latter for the identification of minor components, contaminants, or degradation products. 

Fig. 5. AFM topography (A) and phase (B) images of PS-h-PFS thin films prepared from 1.0 wt% solution of polymer in toluene prior to any annealing. Some limited short-range order is present as indicated by the Fourier transform data shown as an insert in (A).

Fig. 8. AFM topographic images of PS-PFS thin films prepared from 0.5 wt% solutions of polymer in toluene on channel cut topographically defined substrates (600 nm channels) after solvent annealing in THF at room temperature for (A) 0 min, (B) 15 min, (C) 30 min,...

For processing of PBl, it is often dissolved in DMAc. Especially at a high PBl content, e.g., >20 wt%, formation of agglomerates reduces the shelf life of the solution, as indicated by an increase in solution viscosity and resin precipitation. Therefore, a small amount of LiCl (i.e., 1.5 wt%) may be added as stabilizer [20, 21]. Thin films prepared from such solutions can be washed to remove LiCl by immersion in water at 85 °C for 1 h [22]. To speed up the PBl dissolution, increased temperatures are often necessary. In some cases also pressure reactors are used to increase the temperature up to over 260 °C [23]. At these conditions, the water content of the polymer must be reduced by drying at >70 °C in vacuo and the water content of DMAc should be lower than 0.03 %, to avoid hydrolysis of the solvent. It was also reported that the solubility is reduced by the presence of oxygen, and an inert atmosphere (nitrogen or argon) was recommended [23]. 

Figure 3-10 shows the XRD patterns of the iridium oxide thin films prepared from the solution with acetic acid (Nishio, 1999b). Iridium oxide thin films were prepared on glass substrates coated with ITO, and were heat-treated at various temperatures. Crystallization began at 400°C, and the diffraction patterns agreed with that of Ir204-wH20. The amorphous and crystalline iridium oxide thin films prepared were brown. The crystalline... 

Figure 3-9. XPS spectra of the thin films prepared from the solutions (a) without and (b) with CH3COOH.

Niesen T.P., DeGuire M R. Review deposition of ceramic thin films at low temperatures from aqueous solutions. J. Electroceramics 2001 6 169-207 Ohya Y., Miura Y., Ban T., Takahashi Y., Nishigaki S., Okamoto Y., Harada A. Gas sensing properties ofSn02 thin films prepared from aqueous sol. Res. Rep. Center for Cooperative Research Gifu Univ. 1997 No. 7 87-91... 

The heating rate of the thermal annealing used for the crystallization of the amorphous layer has a strong effect on the heterostructural characteristics of the crystalline film and therefore on the electrical properties. Figure 27.13 shows the Rutherford backscattering spectroscopy (RBS) spectra of two (Ca, Pb)Ti03 perovskite thin films prepared from the same precursor solution, but annealed at 650 °C with a relatively slow ( 8°Cs ) and a rapid ( 30°Cs ) heating rate. 

Table 27.3 Heterostructural characteristics and electrical properties (dielectric, ferroelectric, and pyroelectric) of two (Ca, Pb)Ti03 thin films prepared from the same precursor solutions but crystallized with different thermal annealing rates for the ceramic conversion.

Figure 7.13 High-resolution XPS data of the Mo 3-D core level peaks observed for molybdenum oxide thin films prepared from (a) anhydrous and (b) ambient-based precursor solutions as a function of annealing temperature in a nitrogen atmosphere. (Reprinted from ref. 74, with permission from John Wiley and Sons, http //onlinelibrary.wiley.com/ doi/10.1002/adma.201003065/abstract.)...

Bouroushian M, Loizos Z, Spyrellis N, Mamin G (1997) Hexagonal cadmium chalcogenide thin films prepared by electrodeposition from near-boihng aqueous solutions. Appl Surf Sci 115 103-110... 

Because of the complexities involved in understanding cause-effect relationships, an alternative approach to control the thin film microstructure has been pursued by some investigators—the use of statistically designed experiments to identify key processing parameters.114115 In these approaches, as illustrated in Table 2.6 for a Plackett-Burman screening study,114 limiting values for various experimental parameters are chosen. Films are then prepared from solutions synthesized under these conditions, and resulting film... 

In transmission electron microscopy (TEM), a beam of highly focused and highly energetic electrons is directed toward a thin sample (< 200 nm) which might be prepared from solution as thin film (often cast on water) or by cryocutting of a solid sample. The incident electrons interact with the atoms in the sample, producing characteristic radiation. Information is obtained from both deflected and nondeflected transmitted electrons, backscattered and secondary electrons, and emitted photons. 

The composites were prepared from solutions of mNA and PMMA with varying loading degrees (between 30 wt % and 90 wt %), using toluene as a solvent. Thin films (30-40 fim) were cast on a glass slide and the solvent was... 

The preparation of the polymer material as a very thin film (deposited from a solution onto a metallic substrate) was found to be the most satisfactory to reduce the charging effect. 

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