Search results for "Schottky defect"
showing 2 items of 2 documents
Atomic scale DFT simulations of point defects in uranium nitride
2007
Atomic scale density functional calculations are used to predict the behaviour of defects in uranium mononitride (UN). Two different density functional codes (VASP and CASTEP) were employed with supercells containing from 8 to 250 atoms (providing a significant range of defect concentrations). Schottky and nitrogen Frenkel point defect formation energies, local lattice relaxations and overall lattice parameter change, as well as the defect induced electronic density redistribution, are discussed.
The Structural Disorder and Lattice Stability of (Ba,Sr)(Co,Fe)O3 Complex Perovskites
2011
The structural disorder and lattice stability of complex perovskite (Ba,Sr)(Co,Fe)O3, a promising cathode material for solid oxide fuel cells and oxygen permeation membranes, is explored by means of first principles DFT calculations. It is predicted that Ba and Sr ions easily exchange their lattice positions (A-cation disorder) similarly to Co and Fe ions (B-cation disorder). The cation antisite defects (exchange of A- and B-type cations) also have the low formation energy. The BSCF is predicted to exist in an equilibrium mixture of several phases and can decompose exothermically into the Ba- and Co-rich hexagonal (Ba,Sr)CoO3 and Sr- and Fe-rich cubic (Ba,Sr)FeO3 perovskites.