Silicates disilicates

Pyrosilicates (Si207)6- - soro-silicates, Disilicates Two tetrahedral units are joined by sharing the O at one comer, thus giving (Si207)6-. The structure possessed by them are called island silicates stmcture(Fig)... 

Utilizing this description of silicate glass formation, we suggest models to explain the incorporation of 4+ and 6+ actinide ions in sodium disilicate glass. During cooldown,... 

C09-0080. The second simplest silicate is the disilicate anion, Si2 O7 , in which one oxygen bridges... 

In the route used in this work, a monomeric or oligomeric silicate is protonated, the resulting silicic acid is esterified, and the alkyl silicate is organodealkoxylated. In each step, the siloxane framework is fully or substantially preserved. For the case starting with a metal disilicate the reactions can be represented as ... 

NMR studies H, 13C, 29Si) demonstrated that the zwitterionic 5Si-silicates 53-60 and 63-70 and the biszwitterionic A5Si, A5Si -disilicates 72-74... 

Disilicates or soro-silicates Discrete [Si207] units formed by two [Si04] tetrahedra sharing a common oxygen Thortveitite, Sc2(Si207) Hemimorphite, Zn4(0H)2(Si2O7)H2O... 

Although the metasilicates, disilicates, and other silicates in which tetrahedron corners are shared are very stable, the corresponding compounds of phosphorus and sulfur are unstable. The explanation of... 

The rule reqiiires that in silicates the silicon tetrahedra share no elements with each other if the oxygen-silicon ratio is equal to or greater than four. This is found t o be vrue in general (topaz, zircon, olivine, other orthosilicates), Most of the few exceptional substances now known contain extra oxygen atoms in the form of hydroxide ions. These include the clay minerals, micas, and chlorites, discussed above, and also the mineral hemimorphite, Zn[Pg.561]

Simple Silicates. The most important simple silicate glass-ceramics are based on lithium metasilicate [10102-24-6], Li SiO, lithium disilicate... 

In this paper, we report on the synthesis and structural characterization of a series of related zwitterionic (molecular) spirocyclic X Si-silicates (mononuclear A, Si-silicon(IV) complexes) containing two bidentate l,2-diolato(2-) ligands derived from a-hydroxycarboxylic acids, such as glycolic acid, 2 methyllactic acid, benzilic acid, and citric acid. In addition, some analogous zwitterionic X Ge-germanates (mononuclear X Ge-germanium(rV) complexes) are described. Furthermore, we report on the synthesis and structural characterization of related zwitterionic x Si,X Si -disilicates (binuclear X Si-... 

Rare earth silicates exhibit potential applications as stable luminescent materials for phosphors, scintillators, and detectors. Silica and silicon substrates are frequently used for thin films fabrication, and their nanostructures including monodisperse sphere, NWs are also reliable templates and substrates. However, the composition, structure, and phase of rare earth silicates are rather complex, for example, there are many phases like silicate R2SiOs, disilicate R2Si207 (A-type, tetragonal), hexagonal Rx(Si04)602 oxyapatite, etc. The controlled synthesis of single-phase rare earth silicate nanomateriais can only be reached with precisely controlled experimental conditions. A number of heat treatment based routes, such as solid state reaction of rare earth oxides with silica/silicon substrate, sol-gel methods, and combustion method, as well as physical routes like pulsed laser ablation, have been applied to prepare various rare earth silicate powders and films. The optical properties of rare earth silicate nanocrystalline films and powders have been studied. 

Deer, W. A., R. A.. Howie, and J. Zussman (1986). Rock Forming Minerals, Vol. IB Disilicates and Ring Silicates. London Longmans. 

Figure 10.4. A. Relationship between the Li isotropic chemical shift and the composition of lithium silicate glasses. B. Relationship between the Li and "Li isotropic chemical shift and the composition of a series of (Li.Na) disilicate glasses. The open circles denote the Li shifts, the filled squares denote the Li shifts. From Gee et al. (1997), by permission of Elsevier Science.

FIGURE 22.1 Classes of silicate structures, (a) Symbol used for the SiOj" tetrahedron. This top view of the symbol shows a red circle to represent the fourth oxygen atom at the top of the tetrahedron. The black dot represents the silicon atom at the center of the tetrahedron. Bear in mind that all of these structures are actually three dimensional. Planar projections are used here for convenience of representation, (b) Disilicate, (c) Cyclosilicate, (d) Infinite single chain, (e) Infinite double chain, (f) Infinite sheet, (g) Infinite network (cristobalite, Si02). 

Fig. 16.1 Various silicate structures (a) Si04 tetrahedron. When carrying a -4 charge, this is the orthosilicate ion. (b) The disilicate anion, (c) Portion of an infinite single chain. (SiOdw""- (d) Portion of an infinite double chain or band. (Si40u] . (e) Portion of a sheet or layer structure, [SiiOsl, " .

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