Influence Of Sodium Content Research Articles

Blast Furnace Slag Hydration in an Alkaline Medium: Influence of Sodium Content and Sodium Hydroxide Molarity

AbstractThe reaction of blast furnace slag in sodium hydroxide (NaOH) solutions of different molarities is evaluated. The compressive strength of the activated slag does not scale with the molarity...

P3 Na0.9Ni0.5Mn0.5O2 Cathode Material for Sodium Ion Batteries

NaxNi0.5Mn0.5O2 (0.5 ≤ x ≤ 1.2)-layered oxides have been prepared and studied as cathode materials in sodium metal cells. The influence of sodium content on the structure and electrochemical perfor...

Coefficients of Thermal Expansion of Al- and Y-Substituted NaSICON Solid Solution Na3+2xAlxYxZr2−2xSi2PO12

Because of an increasing interest in NaSICON materials as electrolyte materials in all-solid state sodium batteries, their thermal expansion was investigated in this study. The thermal expansion coefficient (CTE) of the Al and Y-substituted NaSICON compositions Na3+2xAlxYxZr2−2xSi2PO12 with 0 ≤ x ≤ 0.3 was obtained by dilatometry and compared to the CTE derived from the lattice parameters using high-temperature X-ray diffraction. The difference in CTE obtained from techniques, the influence of sodium content and central metal cation on CTE, as well as other observations such as phase changes are described and rationalized.

Influence of sodium content on the properties of bioactive glasses for use in air abrasion

Air abrasion is used in minimally invasive dentistry for preparing cavities, while removing no or little sound dentine or enamel, and the use of bioactive glass (rather than alumina) as an abrasive could aid in tooth remineralization. Melt-derived bioactive glasses (SiO2–P2O5–CaO–CaF2–Na2O) with low sodium content (0 to 10 mol% Na2O in exchange for CaO) for increased hardness, high phosphate content for high bioactivity and fluoride content for release of fluoride and formation of fluorapatite were produced, and particles between 38 and 80 µm in size were used for cutting soda-lime silicate glass microscope slides and human enamel. Vickers hardness increased with decreasing Na2O content, owing to a more compact silicate network in low sodium content glasses, resulting in shorter cutting times. Cutting times using bioactive glass were significantly longer than using the alumina control (29 µm) when tested on microscope slides; however, glasses showed more comparable results when cutting human enamel. The bioactive glasses formed apatite in Tris buffer within 6 h, which was significantly faster than Bioglass® 45S5 (24 h), suggesting that the hardness of the glasses makes them suitable for air abrasion application, while their high bioactivity and fluoride content make them of interest for tooth remineralization.

Effect of sodium on the CoMo/γ-Al2O3 system. Part 1.—Influence of sodium content on the state of dispersion and on the nature of the cobalt supported on γ-Al2O3

The effect of sodium content on the dispersion of cobalt on the surface of γ-Al2O3 as well as on the type of cobalt species formed on it have been studied using diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, X-ray powder analysis, electron microscopy and thermo-programmed reduction; two series containing, respectively, 2.1 and 8.8 % Co have been investigated.The former series showed a marked increase in the dispersion of cobalt on the surface of the support, as revealed by X.p.s., when the sodium content increased from 2.3 to 5.7 %. In this composition range, a considerable transformation of Co3O4 into CoAl2O4, as well as a shift of the distribution of cobalt species from the homogeneous to heterogeneous, have been observed.In contrast, virtually no change was observed for the 8.8 % Co series throughout the sodium composition range.

Effect of sodium on the CoMo/γ-Al2O3 system. Part 2.—Influence of sodium content and preparation methods on the state of dispersion and nature of molybdenum supported on γ-Al2O3

The effect of preparation method, calcination temperature and sodium content on the dispersion of molybdenum on the surface of γ-Al2O3, as well as on the kind of molybdenum species formed thereon, has been studied using diffuse reflectance spectroscopy (d.r.s), X-ray powder analysis (X.r.), X-ray photoelectron spectroscopy (X.p.s.), analytical electron microscopy (a.e.m.) and electron paramagnetic resonance (e.p.r.).Two series of specimens (each series containing 6 samples having various amounts of sodium) containing 12% MoO3 have been prepared by, respectively, wet and incipient wetness impregnations of sodium-doped γ-Al2O3 with ammonium paramolybdate aqueous solution.The adsorption of MoVIvia polymeric species, the presence of MoV after calcination at 300°C and the formation of small amounts of Al2(MoO4)3 after calcination at 500°C and above have been observed for a weakly-doped specimen prepared by pore volume impregnation. The formation of Na2MoO4 is observed only for high Na content, irrespective of the preparation method used.The dispersion of molybdenum, as measured by X.p.s., for calcination temperatures of 500°C, is virtually independent of the sodium content up to 3.6% Na; it decreases above this content. Calcining at 300°C leads to lower dispersion; sodium has no appreciable effect.Some mechanisms explaining the results are proposed.