Lithium silicate glasses

Lithium oxide(s), 15 134, 141 Lithium perchlorate, 3 417 15 141-142 dessicant, 3 360 in lithium cells, 3 459 Lithium peroxide, 15 142 18 393 Lithium phosphate, 15 142 Lithium-polymer cells, 3 551 in development, 3 43 It Lithium primary cells, 3 459-466 Lithium production, 9 640 Lithium products, sales of, 15 121 Lithium salts, 15 135-136, 142 Lithium secondary cells, 3 549-551 ambient temperature, 3 541-549 economic aspects, 3 551-552 high temperature, 3 549-551 Lithium silicate glass-ceramics, 12 631-632... 

Fig. 5.17. Si MAS NMR spectra of lithium silicate glasses and their decomposition to Gaussian components both in terms of the chemical shift (8 in ppm, with Gaussians shown as dotted lines on left-hand side above) and in terms of Si-O-Si bond angle (a) distribution (right-hand side above). Samples studied were (a) vitreous silica (b) 15 Li,0-85 SiOj glass (c) 33.3 LijO-bb. SiOj glass (d) 40 Li,O-60 SiO, glass (after Selvaray et al., 1985 reproduced with the publisher s permission).

Figure 4.20. Distribution of Q" units in a binary silicate glass, predicted by A. binary distribution model, and B. random statistical distribution model, from Dupree et al. (1987). C. Experimental data for lithium silicate glasses plotted against the line calculated from the binary distribution model (dashed). From Dupree et al. (1990), by permission of Elsevier Seience.

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.

Fig. 15 Schematic illustrating lithium clustering in lithium silicate glasses...

Fig. 16 Site-resolved Si Li REDOR data vs NTr/s j on a lithium silicate glass, using...

Figure 8.6 Effect of phase separation on the electrical conductivity at 300 °C of lithium silicate glasses. (Data supplied by B. M. Wright)...

M. R. DeSocio, in Effect of Potassium Content on the Properties of Lithium Silicate Glass-Ceramics, M. S. Thesis, Alfred University, 1985. 

V. R. Stenshorn, in Effect of Hydroxyl Concentration on the Crystallization of a Lithium Silicate Glass-Ceramic, M.S. Thesis, Alfred University, 1992. 

Infinite A leads to the binary model, whilst A = 0 leads to a completely random distribution. Gurman found that the lithium silicate glasses have AE/kT = 1.5 0.5[21j.However, some NMR data [20,22, 23] from alkali-silicate glass systems support the binary model. On the other hand, other NMR data [24,25, 26, 27] and a Raman investigation[28] support the bondordering model. 

Cao, Y. and Cormack, A.N. (1995) Structure and Alkali Migration Behavior in Lithium Silicate Glasses, J. Non-Crys. Solids, (submitted)... 

Commercially available, highly efficient liquid and solid scintillators were tested as standards for comparison with our samples. Ultima Gold (PerkinElmer) is a standard liquid scintillation counting cocktail, containing PPO (ca. 1 wt %) in a mixture of aromatic compounds, and phosphate and succinate surfactants. BC-400 (Bicron) is a plastic scintillator composed of organic fluors, PPO and POPOP, at <3 wt % in PVT. KG2 (Bicron) is a cerium-activated lithium silicate glass scintillator, containing 7.5 wt % of Li (95% i) as a neutron absorber, and Ce as a scintillation material. 

Silica O crystallizes from lithium silicate glasses during devitrification at low temperature. It has a crystal lattice similar to quartz and may simply be high quartz" stabilized below 573 C, the normal transition temperature, to low quartz (53, 70) by inclusions of metal ion impurities. The only way pure material can be obtained is by neutron bombardment of quartz. 

Silica rapidly depolymerizes in the presence of strong alkali. Thus colloidal silica can be converted to a solution of sodium polysilicate containing from 4.2 to 6.0 moles of silica per mole of sodium oxide (738) or lithium polysilicate and lithium stabilized sols with 4-25 moles of silica oxide per mole of lithium oxide (739). These compositions cannot be obtained by dissolving a sodium or lithium silicate glass, nor by dissolving sand in the alkali because of the peculiar fact that lithium silicate is not soluble in hot water. For lower ratio silicates the advantage of starting with colloidal silica is only a matter of convenience because of the rapid reaction rate. 

Chemical Machining. Selective etching or dissolution of material to shape a component. See leachable glass LITHIUM SILICATE GLASSES. 

Fotoform Process. Tradename. An image is nucleated and crystallized within a lithium silicate glass, doped with an appropriate sensitizer. The pattern can then be preferentially etched away to produce holes, patterns, and internal channels, with an accuracy of a few microns. 

It must be noted that the reaction mechanisms in glass/glass-ceramic powders are usually of a very complex nature. Jacquin and Tomozawa (1995) addressed the complex sintering process and the various ways of controlling it in the fabrication of lithium silicate glass-ceramics. 

Dupree R., Holland D., and Mortuza M.G., "A MAS-NMR Investigation of Lithium Silicate Glasses and Glass-Ceramics,"/. Non-Cryst. Solids, 116, 148-60 (1990). 

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