Interstitial and substitutional zirconium in SrTiO3

Journal Article · Wed Feb 22 00:00:00 EST 2012 · Computational Materials Science, 53(1):153-157

DOI:https://doi.org/10.1016/j.commatsci.2011.08.023· OSTI ID:1033827

Jaffe, John E; Van Ginhoven, Renee M; Jiang, Weilin

We investigate Zr in SrTiO3 (STO) as a model for nuclear waste forms in which the fission product Sr90 eventually decays to stable Zr through beta emission. The transformation of a divalent into a tetravalent constituent is expected to affect the long-term structural and chemical stability of this solid. Computational methods of electronic structure theory, specifically the density functional theory (DFT) within the supercell model, are used to predict the thermodynamic stability and electronic states of interstitial and Sr- or Ti-substituted Zr atoms in the STO lattice. Native defects such as vacancies and antisites are also considered. When Zr replaces Sr, its most stable configuration is to simply occupy the Sr site (instead of, for example, replacing a Ti and displacing the Ti to the Sr site.) For Zr added to the lattice, its most stable configuration is to replace a Ti, making a ZrTi impurity plus a Ti interstitial (as opposed to the Zr just remaining as an interstitial atom.) ZrSr is predicted to be a double electron donor, ZrTi is electrically inactive and interstitial Zr and Ti are predicted to be quadruple donors, with all donor levels in the conduction band. ZrSr and the tetravalent interstitials are all predicted to increase the crystal volume, and the interstitials also are predicted to lead to a tetragonal distortion of the lattice. Experiments with injection of Zr atoms into STO qualitatively confirm these predictions of crystal structural changes.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1033827
• Report Number(s): PNNL-SA-80184; AF5805000; TRN: US1200610
• Journal Information: Computational Materials Science, 53(1):153-157, Vol. 53, Issue 1
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
ATOMS
BINDING ENERGY
CONFIGURATION
DEFECTS
ELECTRONIC STRUCTURE
ELECTRONS
FISSION PRODUCTS
FUNCTIONALS
INTERSTITIALS
RADIOACTIVE WASTES
STABILITY
THERMODYNAMICS
TRANSFORMATIONS
VACANCIES
VALENCE
ZIRCONIUM
Zirconium
strontium titanate
nuclear waste form