Film epitaxial crystal limit

In this system, the fomiation of CdS is strictly limited to the surface substrates so that no influence to the film growtn can be considered to result from the solution phase reaction. Deposition of nanosized epitaxial dots on Au(l 11) has been successfully achieved by using this strategy.40,41) However, long-range epitaxial crystal growth seems to be difficult, probably due to the very low solubility of CdS in DMSO... 

The limited number of high quality substrates suitable for oxide epitaxy, together with the wide range of structural properties exhibited by oxides, may require the use of a substrate with a different crystal symmetry than the film material. If the crystal symmetries are sufficiently different, antiphase boundaries (ABPs) may result during nucleation of the initial monolayers. Such APBs tend to be very stable and thus typically become permanently ingrained in the film structure. The question we address here is the effect that APBs in the bulk of the film have on the surface structure. 

Solubility limits in solid solutions can be widened by annealing (tempering) a high-temperature phase or depositing a thin film of a solid solution on a substrate with the necessary structure (epitaxy). Thus, a single-crystal layer (50-60 nm) of the KCI0.5I0.5 composition (not known to exist as bulk mixed crystals), have been obtained on a KBr substrate at low temperature [98]. Solid solutions MgO-CaO of all concentrations were prepared as epitaxial layers on the MgO substrate at T=300 °C [99], their unit cell parameters conform to Vegard law. 

One of the important limitations in using single-crystal and epitaxial films as electrodes is that they are very expensive to prepare. Therefore, most of the studies have been undertaken with polycrystalline electrodes. 

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