Glasses Tech

March 8, 2010

Effect of current density on the electron microprobe analysis of alkali aluminosilicate glasses

Filed under: Glasses 2005 — admin @ 7:22 am

Eyeglasses

In a previous work (Morgan and London 1996), we proposed an optimized procedure for electron microprobe analysis (EMPA) of rhyolitic glasses using a broad (20 µm diameter), low-current (2 nA) fixed beam. Some important applications for EMPA of glass, such as vitreous inclusions in minerals and experimental run products, require smaller beam diameters that produce greater areal current densities (expressed as nA/µm2). For these situations, we have assessed the effect of areal current density on the migration of Na and its concomitant effects on other elements and their ratios during EMPA of granitic glasses. Anhydrous and hydrous glasses of a haplogranite composition (Ab38.23Or29.31Qtz33.37C0.10) were analyzed at 20 kV accelerating potential, using 2–50 nA beam currents, fixed beam diameters of 2–20 µm, and counting times scaled to yield similar analytical uncertainty at each condition (~2.6% relative for Na2O). (more…)

Quantification of Anion and Cation Release from a Range of Ternary Phosphate-based Glasses with Fixed 45 mol% P2O5

Filed under: Glasses 2005 — admin @ 7:15 am

This article reports on the use of ion chromatography (IC) to investigate extensively the release profiles of both cations and anions and characterize the relationship between composition and degradation for a ternary-based Na2O-CaO-P2O5 glass system developed as biomaterials. Studies are carried out on glasses with the formula 45P2O5-55(xCaO-Na2O) in deionized water, where x = 30, 35, and 40 mol%, using a cumulative release method, where the solution is changed at regular intervals. (more…)

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