Self-flux method

The Y concentration in the BaO-CuO liquid is very low. Therefore, the self-flux method, which is commonly used to obtain single crystals in incongruent melting systems, might not be helpM in production of large crystals. 

Fig. 22. A brief classification of R123 crystal growth techniques on a basis of different phenomena taking place at various interfaces between solid, liquid and gaseous phases participating in the solidification process (a) possible interface boundaries and phenomena connected with the presence of such interfaces (b) different interfaces present in the self-flux method note that numbers in brackets correspond to the general scheme of classification (a) (c) a number of interfaces and phenomena of some importance for the unidirectional solidification method note that (crystal-high-temperature phase and melt-high-temperature phase) interfaces are close to each other (d) different interfaces and phenomena to be considered in the SRL-CP pulling technique of bulk crystal production note that solute transport and nudeation can be controlled in order to achieve a desired morphology of the crystal.

In the case of Y123, variation of the initial flux composition is advantageous in the preparation of thick crystals by the self-flux method (sect. 5.1) or in the control of crystalline film orientation in the LPE method (sect. 5.4). However, for LRl 23 crystals the control of liquid composition is crucial even for their superconductivity enhancement. 

There are some indications that the self-assembly method yields sufficiently stable structures. Kwak et al. (2001) used a self-assembly method for Ti02 nanoparticles with a size of 2 nm for aromatic polyamide reverse osmosis membranes, in view of flux enhancement they applied X-ray photoelectron spectroscopy to observe the stability of the attachment of the nanoparticles and concluded that the adsorbed particles were sufficiently tightly bound to the surface to withstand various washing procedures and even harsh reverse osmosis-operating conditions. 

The grafting to method was used to anchor polymer chains onto the surface of silica particles and silicon wafers (Scheme 1). The synthetic procedure starts with covalent grafting of GPS to the surface. A self-assembled monolayer of GPS on silicon wafer surfaces was prepared according to the procedure suggested by Luzinov [32], For this, Si wafers were immersed in a 1% GPS toluene solution for 15 h under dry Ar atmosphere (< 1 ppm H2O). After treatment, GPS modified wafers were washed 3 times in dry toluene under dry Ar atmosphere to avoid polymerisation of non-grafted GPS and precipitation of particles. Afterwards, the silanized wafers were washed 2 times with ethanol in ultrasonic bath for 5 min followed by drying with nitrogen flux. The thickness of the GPS layer was determined by null ellipsometiy. 

Regen58 used amphotericin B as a design basis for the structural requirements of an ion channel. Composed of a rigid, hydrophobic sterol nucleus and flexible hydrophilic chains, 50 was expected to function via self-assembly in a membrane bilayer. Cation flux was assessed using Lehn s NMR method and comparisons were made with the bouquet molecules. Ionophoric activity was similar to the more sophisticated bouquet molecules (maximum entry achieved in ca. 60 h), but Na+ transport was significantly less than recorded with amphotericin B. 

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