Synthetic glasses, zeolitization

Zeolitization of Synthetic Glasses. The formation areas of some products, obtained in different conditions from both series of glasses (Figure 1), are shown in Figures 2 and 3. Figure 2 refers to the series... 

A number of matrices have also been used for the preparation of semiconductor nanoparticles, whereby the particulate material is grown within and subsequently fills the cavities of the host material. These includes zeolites,361 glasses,362 and molecular sieves,363-365 and can be viewed as nanochambers which limit the size to which crystallites can grow. Other synthetic methods include micelles/microemulsions,366-369 sol-gels,370,371 polymers,372-377 and layered solids.378... 

Perchloryl fluoride does not attack glass at moderate temperature, but decomposes at 25°C on contact with activated Si02 or AI2O3, particularly in the presence of small amounts of H2O. With other surface-active materials, such as charcoal, ignition may take place. However, there is no reaction at room temperature with synthetic zeolites. It passes freely through a 4 A molecular sieve, but is completely absorbed... 

Glass-ceramics based on natural or synthetic basalts, various zeolites, and apatite/britholite were also developed (Saidl Ralkova 1966 Hayward 1988 Wronkiewicz et al. 1996 Sinkler... 

Semiconductor clusters have traditionally been prepared by the use of colloids, micelles, polymers, crystalline hosts, and glasses. The clusters prepared by these methods have poorly-defined surfaces and a broad size distribution, which is detrimental to the properties of the semiconductor materials. The synthesis of monodisperse clusters with very well-defined surfaces is still a challenge to synthetic chemists. However, some recent approaches used to overcome these problems are (i) synthesis of the clusters within a porous host lattice (such as a zeolite) acting as a template and (ii) controlled fusion of clusters. 

AIELLO (R.), COLELLA (C.) and SERSALE (R.), 1970. Zeolite formation from synthetic and natural glasses. Arne. Chem. Soc. 2nd Int. Zeolite Conf., 48-58. 

A number of novel applications of zeolites depend on the ability to create thin, adhesive films on various substrates. While zeolite films or layers are commonly prepared on dense substrates such as silicon wafers, zeolite membranes are made on porous supports in order to permit permeation through the zeolite layer. Numerous synthetic studies have addressed the goal of obtaining adhesive layers of zeolites on various substrates such as noble and nonnoble metals, glass, ceramics, silicon, and even biological substrates such as cellulose fibers. For a more detailed discussion of zeolite membranes the reader is referred to the article by Julbe in this book. Pertinent reviews to this subject are given in the following references.[57,58]... 

Zeolite Formation from Synthetic and Natural Glasses... 

TJor a long time, the Institute of Applied Chemistry of Naples Univer-sity has been systematically investigating the zeolitization process of glasses, either volcanic (7) or synthetic, with composition near (8, 9) or different (4) from that of the natural ones. 

By using a novel synthetic technique named DBMD, we succeeded in converting glass bulk materials by replacing the glassy part to MFI zeolite crystals from the surface to the inside. A thoroughly converted zeolitic tube and partially converted zeolitic fibers and fabric were prepared with this technique. Seed crystals accelerated crystallization and improved both coverage and uniformity of the crystals. 

---