Sodium borosilicate

The slow rate of dissolution of, or leaching from, durable glasses has led to proposals for the vitrification of nuclear waste. Glasses based on the sodium borosilicate system appear to be favoured because of their ability to dissolve the waste, combined with good chemical durability. Intensive development has taken place over recent ycars and a regular journal is devoted to this topic . 

Waste-Form Stability. If they occur at all, solid state transformations in dry glass and UO2 matrices will be too slow under the temperature conditions of service to be observable in the laboratory at the same temperature. Here we need to extrapolate from high temperature laboratory conditions to low temperature service conditions. It will be desirable to develop an intimate knowledge of the processes of phase separation and devitrification of sodium borosilicate glasses at temperatures below the softening point by meticulous application of electron microscopic. X-ray crystallographic and other techniques. The glasses will contain inactive elements representative of the fission product... 

Stefanovsky, S. V. 1989. The effect of sulfur oxide (VI) on phase separation in sodium borosilicate glasses. Glass and Ceramic, 3, 10-11 (in Russian). 

Figure 2. SIMS depth profiles for a sodium borosilicate glass blank sample, air-exposed only (a), and sample exposed to aqueous leaching at 25°C for 30 min (b).

Figure 3. Comparison of SIMS depth profiles of aqueous leaching of a sodium borosilicate glass, for 30 min (a). Key ----------, 0°C and--------, 25°C. Error func-...

This contribution describes the preparation of mechanically stable flat porous glass mem-brcines with variable texture properties on the basis of phase-separated sodium borosilicate initial glasses and their characteri2ation with a series of techniques. 

Textural properties of some ultrathin porous glass membranes prepared from a sodium borosilicate initial glass by varying of the conditions of heat treatment ... 

Ultrathin porous glass membranes with variable texture properties were prepared from a Si02-rich sodium borosilicate initial glass by careful fine timing of the conditions of heat treatment for phase-separation. Pore sizes between < 1 and 120 nm can be realized. The membranes are characterized by a narrow pore size distribution. The transport, optical and mechanical properties vary with the pore size. The tailorable texture and transport characteris-... 

K. B. Albaugh, Electric phenomena during anodic bonding of silicon to sodium borosilicate glass, J. Electrochem. Soc. 138, 3089, 1991. 

The Si NMR spectra of a series of sodium borosilicate glasses (Bunker et al. 1990) show that in compositions containing 30-40 mol% B2O3 the predominant structural unit is Q" (8 of about — 110 ppm), but at lower B2O3 contents the Si shift becomes less negative, reflecting an increase in the number of Q" (1B) (—105 ppm) and Q (OB) units (— 90 ppm). The latter component could also arise from the presence of Q (3B)... 

A similar plot of 8(B03) for the series of ternary sodium borosilicate glasses shows a similar trend with the mole fraction of Si02 (x) but with much greater scatter even when the compositions in the immiscibility region are omitted (Martens and Miiller-Warmuth 2000) (Figure 7.14B). The fitted line to these data is given by ... 

Table 1 lists sodium ion resistivities at 300°C for polycrystalline ceramic conductors (e.g., 6"-alumina, and NASICON) and sodium ion conducting glasses (e.g., NASIGLAS and a sodium borosilicate glass). (The terms NASICON and NASIGLAS were defined... 

The so called porous silica is made by the acid etching of annealed sodium borosilicate glass. The bulk structure is glass mainly of silica and has a uniform pore size distribution in the mesopore region. These are used as a source of silica glass. 

Expressions have been derived for determining the content of tetrahedrally co-ordinated boron in sodium borosilicate glasses from their composition. ... 

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