Summary This study investigates the oxygen-scavenging behavior of bisulfite ions in monoethylene glycol (MEG)/water mixtures at concentrations commonly found in gas-transportation pipelines. Temperatures and pH values were varied. The influence of transition-metal (TM) ions to catalyze the bisulfite oxygen scavenging was studied. Experimental results indicate that MEG significantly inhibits bisulfite oxygen removal, which is hindered at low pH values and, to some extent, temperature. TMs can accelerate the oxygen-scavenging reaction in pH-unadjusted solutions, although the rate was still lower than that of the pH-adjusted solutions. The possible mechanism for such behavior and industrial implications are discussed.

We have studied oxygen diffusion in thin films of Pb(Zr,Ti)O3 on Pt/Ti/SiO2/Si <100> multilayer substrates using 18O as a tracer. The PZT films were synthesized using the sol-gel technique and crystallized in air at 650° C for 30 minutes. Diffusion experiments were conducted in one atmosphere of 18O2 at tmipertures between 400-600°C, the extent of exchange was monitored using secondary ion mass spectromentry. Exchange profiles were modeled using solutions of the diffusion equation with boundary conditions for a layer with finite thickness. Significant exchange (>60%) of 16O by 18O was measured after treatment under conditions similar to those used for crystallization. At low levels of exchange, oxygen diffusion does not follow a simple Fickian profile and differences exist between nominally identical films. These results suggest that oxygen exchange is sensitive to the film's microstructure.

The movement of oxygen through MgO and BaF2 overcoats on YBa2Cu3O7−Δ has been studied using 18O tracer diffusion techniques. By analyzing the 18O and 16O signals from secondary-ion mass spectrometry depth profiles, the motion of small concentrations of oxygen in both insulating and oxygenated hosts has been tracked. BaF2 was found to be &lt;m1;37p&gt;transparent to oxygen diffusion while MgO blocked its motion during 10 min 500–600 °C anneals. Uncovered YBa2Cu3O7−Δ films were also found to exchange up to 90% of their oxygen during similar anneals. These results have important ramifications for reoxygenation steps during device fabrications.