Multicomponent thin-film preparation

In the remainder of this article specific examples of thin film synthesis using PLD are described. These examples are chosen to illustrate the unique characteristics of PLD that make it a powerful technique for the preparation of complex multicomponent solids and for exploratory synthesis of new materials. 

In contrast, physical techniques of thin film synthesis are based upon evaporation or sputtering of elemental or multicomponent sources and subsequent deposition of this material onto a substrate molecular precursors do not play a significant role in thin film synthesis via these techniques. Examples of physical techniques used to prepare thin films include (1) Molecular Beam Epitaxy (2) sputtering, ... 

Spin-casting is the most common method of preparation of thin films of desired 1-3 (im thickness. Material solubility in traditional spin-casting solvents, solution viscosity, and spinning speed are important variables that define material homogeneity and thus scattering loss. For multicomponent composite materials, care must be exercised to avoid phase separation. Typical scattering loss values should be a few tenths of a dB/cm but losses of many dB/cm can be observed if the aforementioned conditions are not controlled. 

Important features of the sol-gel method are better homogeneity compared to the traditional ceramic method, high purity, lower processing temperature, more uniform phase distribution in multicomponent systems, better size and morphological control, the possibility of preparing new crystalline and non-crystalline materials and, lastly, easy preparation of thin films and coalings. The sol-gel method is widely used in ceramic technology and the subject has been widely reviewed [1-3]. 

FTIR spectra of a multicomponent borosilicate xerogel after drying at room temperature or heating to temperatures ranging from 200 to 550°C in air. Samples were diluted in KBr except the 550°C sample, which was prepared as a thin film on an intrinsic Si substrate. Inset is DTA trace during heating in air at 10 C/min (146). 

In conclusion, recent research progress on the photofunctional rare earth materials based on ionic liquids has been summarized, which mainly consist of two important classes one is the rare earth compounds dispersed or dissolved in ionic liquids, even including the rare earth compounds of ionic liquids with exact crystal structures the other is the photofunctional rare earth hybrid materials using ionic liquids both as the chemical linkers and host. However, some problems still exist in the field of photofunctional rare earth materials based on ionic liquids. The first problem is the controlled preparation and fabrication of thin film materials of ionic gels based on luminescent rare earth compounds, which is important and necessary for the further applications in optical devices. The second problem is luminescent enhancement and functional integration of the photofunctional rare earth materials based on ionic liquids. Here it is worth pointing out that it is important to develop visible-excitation lanthanide hybrid system and obtain white luminescence through multicomponent assembly of rare earth species and ionic liquids. 

Thin films can be prepared in crystalline or amorphous states, in single layer or in multilayers, or in multicomponent form. In their applications an enormous range of materials has been used, e.g., metals, intermetallics, oxides, nitrides, carbides, elemental or compound semiconductors, glasses, and inorganic and organic polymers. For their preparation for the various applications, numerous techniques have been and are being developed. 

Assuming a polymer thin film is prepared from a single-solute solution, fhree interaction pairs, namely, polymer-solvent, polymer-substrate, and solvent-substrate, determine the spreading and the stability of the film. By adding another polymer into the solution, six interaction pairs contribute to the final sfructure of the resulted film, which is much more complex. On the other hand, in order to get better performance or multifunctions, multicomponents (here, we focus... 

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