Self-assembly and phase behavior of germanium oxide nanoparticles in basic aqueous solutions.

作者: Jeffrey D Rimer , Daniel D Roth , Dionisios G Vlachos , Raul F Lobo , None

DOI: 10.1021/LA062828Q

关键词: Aqueous solutionConductivityDissociation (chemistry)Inorganic chemistryAnalytical chemistryGermaniumBasic solutionPhase diagramSmall-angle X-ray scatteringChemistryGermanium oxide

摘要: We show that germania nanoparticle self-assembly in basic aqueous solutions occurs at a critical aggregation concentration (CAC) corresponding to 1:1 GeO2/OH- molar ratio. A combination of pH, conductivity, and small-angle X-ray scattering (SAXS) measurements was used monitor the effect incremental additions germanium (IV) ethoxide sodium hydroxide or tetraalkylammonium cations. Plots pH versus total varying alkalinities generated phase diagram with three distinct regions. The analyzed thermodynamic model based on chemical equilibria speciation dissociation. model, which uses GeO−H dissociation constant (pK = 7.1) as single fitting parameter, quantitatively captures trends CAC pH. SAXS patterns reveal nanoparticles have either cubic spherical geometry dimension ∼1 nm is independent solution cation. On basis these other literatur...

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