TY - JOUR
T1 - Nanophase transition metal oxides show large thermodynamically driven shifts in oxidation-reduction equilibria
AU - Navrotsky, Alexandra
AU - Ma, Chengcheng
AU - Lilova, Kristina
AU - Birkner, Nancy
PY - 2010/10/8
Y1 - 2010/10/8
N2 - 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.
AB - 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.
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U2 - 10.1126/science.1195875
DO - 10.1126/science.1195875
M3 - Article
C2 - 20929770
AN - SCOPUS:77957732538
SN - 0036-8075
VL - 330
SP - 199
EP - 201
JO - Science
JF - Science
IS - 6001
ER -