Size-Driven Structural and Thermodynamic Complexity in Iron Oxides
Abstract
Iron oxides occur ubiquitously in environmental, geological, planetary, and technological settings. They exist in a rich variety of structures and hydration states. They are commonly fine-grained (nanophase) and poorly crystalline. This review summarizes recently measured thermodynamic data on their formation and surface energies. These data are essential for calculating the thermodynamic stability fields of the various iron oxide and oxyhydroxide phases and understanding their occurrence in natural and anthropogenic environments. The competition between surface enthalpy and the energetics of phase transformation leads to the general conclusion that polymorphs metastable as micrometer-sized or larger crystals can often be thermodynamically stabilized at the nanoscale. Such size-driven crossovers in stability help to explain patterns of occurrence of different iron oxides in nature.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Mar 21, 2008
- Source ID
- 10.1126/science.1148614
Entities
People
- Alexandra Navrotsky
- Juraj Majzlan
- Lena Mazeina
Organizations
- United States Naval Research Laboratory
- University of Freiburg