Rayleigh Scattering Losses in Soda Borosilicate Glasses

Abstract

once the level of the organic species has been reduced by adsorption or complexing, allowing growth of CH crystals. Since the level of silicate ions in solution will be high, the initial hydration will be rapid.However, it is difficult to see how this theory, although it explains retardation, can explain complete inhibition of hydration, since there is no evidence, even after 50 days, that hydration products form in the paste made with 0.1 c7c sodium gluconate, nor does it explain the retention of organic material in pastes with no evidence of hydration products.The SEM micrographs show a distinct change in surface features and thus the inhibition of hydration could be due to a surface phenomenon. Tadros er a1.'* showed that, in the early stages of hydration, the surface of the hydrating C,S particles carries a positive charge due to adsorption of Caz+ ions onto the silica-rich layer left as the Ca2+ ions diffuse out. It seems logical that the sugar-acid anions could adsorb onto this positively charged layer, preventing the nucleation of C-S-H aciculae. Thus the sinks for all ions in solution are poisoned and hydration is halted. This hypothesis assumes that initial hydration does occur, at least to form a small amount of hydration product. This explanation appears to be reasonable, since adsorption onto C3S in an anhydrous system is very limited.:'Because sugars are not readily ionized, the greater effect of gluconic acid at low levels can be readily explained, i.e. adsorption of the negatively charged species on the positively charged surface will be much greater. The additional stability of sugar acids in alkali h a s also been suggested as a reason for their greater effectiveness as retardersi6 and also explains why the sugar-reduced lignosulfonate fractions are as effective as the sugar-containing fractions since it is not the sugars which are responsible for most of the delay in hydration. V. Conclusions(1) The delaying action of calcium lignosulfonates in the hydration of C,S is caused by sugar acids present in the lignosulfonates. The effect is that of a delayed accelerator rather than of a slowing of the hydration rate. (2) Sugar acids are more effective as delayed accelerators of C,S hydration than sugars because of their charge and stability.(3) The delay in hydration is caused by poisoning of the Ca(OH), nuclei and complexing of Ca2+ ions, preventing a growth of Ca(OH),. (4) Inhibition of hydration occurs when the C-S-H nucleation sites on the positively charged surface are poisoned by adsorbed sugar-acid anions.

A unified materials approach to mitigating optical nonlinearities in optical fiber. III. Canonical examples and materials road map

“…Contemporaneously, the binary potassium silicate system was studied with both Rayleigh and Brillouin scattering being investigated as a function of K 2 O concentration. 10 With increasing K 2 O, both p 12 and p 44 photoelasticity coefficients, shear and longitudinal wave velocities, and fictive temperature were found to decrease. Conversely, the refractive index and isothermal compressibility were shown to increase with increasing K 2 O concentration.…”

“…From the perspective of specific systems, as noted in Companion Paper I, a glass system that possesses both refractive index and density values that are roughly independent of composition should exhibit intrinsically low Rayleigh scattering. As an example, binary borosilicates (B 2 O 3 ‐SiO 2 ) possess reduced ∂ε/∂ρ values, whereas binary alkali silicates exhibit reduced <Δρ 2 > values . Accordingly, the sodium borosilicate system is particularly interesting because it exhibits reduced Rayleigh scattering due to these combined effects.…”

“…As an example, binary borosilicates (B 2 O 3 -SiO 2 ) possess reduced @e/@q values, whereas binary alkali silicates exhibit reduced <Dq 2 > values. 12 Accordingly, the sodium borosilicate system is particularly interesting because it exhibits reduced Rayleigh scattering due to these combined effects.…”

“…Ternary silicate glasses also received considerable attention, particularly those in the sodium borosilicate (Na 2 O‐B 2 O 3 ‐SiO 2 ) and sodium aluminosilicate (Na 2 O‐Al 2 O 3 ‐SiO 2 ) systems. As noted by Tynes et al a glass system that exhibits both refractive index and density values that are roughly independent of composition must then exhibit a ∂ε/∂C value of zero (or nearly so), which implies low Rayleigh scattering. Akin to the concept employed here of component additivity to achieve multiple property tailoring, Tynes et al, further postulated that a ternary borosilicate with low total Rayleigh scattering could be achieved by mixing a binary borosilicate (B 2 O 3 ‐SiO 2 ) having reduced ∂ε/∂ρ with a binary alkali silicate exhibiting a reduced <Δρ 2 > value (see Companion Paper I for more detail on these factors).…”

A unified materials approach to mitigating optical nonlinearities in optical fiber. I. Thermodynamics of optical scattering

“…More generally, reductions to the chemical potential difference should reduce Rayleigh scattering. Lastly, as noted by Tynes , the (∂ɛ/∂ C ) term should vanish for glasses where the refractive index and density are largely independent of composition, such as the sodium borosilicate system . In such systems, both density‐ and composition‐related scattering can be reduced.…”