Diffusive equilibrium properties of O2 in amorphous SiO2 nanoparticles probed via dependence of concentration on size and pressure

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Abstract

An experimental study on the diffusiveequilibrium value of interstitial O2 in silica nanoparticles wascarried out on samples with average particles diameter 40, 14,and 7 nm. The investigation was performed by measuring theconcentration of interstitial O2 by Raman and photoluminescencetechniques. The dependence of diffusiveequilibrium concentration on pressure and temperature wasinvestigated in the pressure range from 0.2 to 76 bar and in thetemperature range from 98 to 244 °C. The equilibriumconcentration of interstitial O2 follows Henry’s law atpressures below 13 bar whereas a departure from this modelis observed at higher pressures. In particular, O2 concentration saturates above about 60 bar, reaching a temperature-independentvalue for fixed particles size. The concentration of dissolved O2, under fixed thermodynamical conditions, is size dependent, beinglower in smaller particles. These results evidence an effect of interaction among diffusing species in the dynamics of transport andgive support to a shell-like model for the distribution of O2 in nanoparticles.
Original languageEnglish
Pages (from-to)18044-18050
Number of pages7
JournalJOURNAL OF PHYSICAL CHEMISTRY. C
Volume118
Publication statusPublished - 2014

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • General Energy
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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