Nanophase transition metal oxides show large thermodynamically driven shifts in oxidation-reduction equilibria

Alexandra Navrotsky, Chengcheng Ma, Kristina Lilova, Nancy Birkner

Research output: Contribution to journalArticlepeer-review

219 Scopus citations

Abstract

Knowing the thermodynamic stability of transition metal oxide nanoparticles is important for understanding and controlling their role in a variety of industrial and environmental systems. Using calorimetric data on surface energies for cobalt, iron, manganese, and nickel oxide systems, we show that surface energy strongly influences their redox equilibria and phase stability. Spinels (M3O4) commonly have lower surface energies than metals (M), rocksalt oxides (MO), and trivalent oxides (M2O 3) of the same metal; thus, the contraction of the stability field of the divalent oxide and expansion of the spinel field appear to be general phenomena. Using tabulated thermodynamic data for bulk phases to calculate redox phase equilibria at the nanoscale can lead to errors of several orders of magnitude in oxygen fugacity and of 100 to 200 kelvin in temperature.

Original languageEnglish (US)
Pages (from-to)199-201
Number of pages3
JournalScience
Volume330
Issue number6001
DOIs
StatePublished - Oct 8 2010
Externally publishedYes

ASJC Scopus subject areas

  • General

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