BaZrO3-Ni-defect-formation - Metadata

BaZrO3 is among the most proficient electrolytes for p-SOEC technology, due to its high ionic conductivity and relatively low electrical leakage. Keeping electrical leakage low is, however, somewhat complicated by the need to dope BaZrO3 with acceptor species such as Y or Sc in order to introduce high proton concentrations. One important consideration along these lines is whether NiO, commonly used as a sintering aide in BaZrO3-based p-SOECs, may degrade device performance due to the infiltration of electrically conductive Ni species into and through the electrolyte. Here, we have calculated the formation energies and kinetics of Ni impurities through BaZrO3, considering the presence of dopants and common defects (namely, oxygen vacancies) to understand how factors such as dopant selection and concentration may give rise to problematic levels of Ni permeation.

This spreadsheet contains data related to defect formation energies and migration barriers in BaZrO3, as computed using density functional theory with the VASP package. Specifically, data pertain to defects and defect complexes connected to nickel, which is a commonly used sintering aide in BaZrO3-based solid oxide cells. More details about the information in each tab are provided below:

Tab 1 (parameters): general details regarding calculations settings, etc.

Tab 2 (total energies): calculated energies used to calculate defect formation energies. Specifically: - the energy of the pristine supercell - the eigenvalue of the valence band maximum (VBM) - the calculated band gap using the HSE06 hybrid functional

Tab 3 (chemical potentials): elemental chemical potentials used to compute defect formation energies. The total chemical potential (Column D) is composed of the elemental total energy (column B) plus a chemical potential deviation (column C) based on the thermodynamic stability region of BaZrO3.

Tab 4 (defect formation energies): all information necessary to calculate defect formation energies in BaZrO3. Specifically: - the identity of the point defect - the charge state of the defect (e.g., # of electrons removed, where +2 indicates two electrons removed) - the total energy of the defect supercell as computed with VASP - the finite size correction term to account for periodic boundary conditions (using the approach of Freysoldt, Neugebauer, and Van de Walle) - the numbers of specific elements added or removed from the pristine supercell to create the defect - the formation energy of the defect at the valence band maximum. To extrapolate to a specific Fermi level position, add this value to the charge state times the Fermi level position (e.g., E^form_VBM + q*E_Fermi)

Tab 5 (NEB energies): energies and magnetic moments for migration pathways of nickel interstitial species using the climbing image nudged elastic band (NEB) method with three intermediate images. - configurations include neighboring oxygen vacancies and scandium/yttrium substitutional acceptor species

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