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Title: Oxygen vacancy formation energies in PbTiO 3 / SrTiO 3 superlattice

The defect stability in a prototypical perovskite oxide superlattice consisting of $${\mathrm{SrTiO}}_{3}$$ and $${\mathrm{PbTiO}}_{3}$$ (STO/PTO) is determined by using first principles density functional theory calculations. Specifically, the oxygen vacancy formation energies $${E}_{\mathrm{v}}$$ in the paraelectric and ferroelectric phases of a superlattice with four atomic layers of STO and four layers of PTO (4STO/4PTO) are determined and compared. The effects of charge state, octahedral rotation, polarization, and interfaces on $${E}_{\mathrm{v}}$$ are examined in this paper. The formation energies vary layer by layer in the superlattices, with $${E}_{\mathrm{v}}$$ being higher in the ferroelectric phase than that in the paraelectric phase. The two interfaces constructed in these oxide superlattices, which are symmetrically equivalent in the paraelectric systems, exhibit very different formation energies in the ferroelectric superlattices and this can be seen to be driven by the coupling of ferroelectric and rotational modes. At equivalent lattice sites, $${E}_{\mathrm{v}}$$ of charged vacancies is generally lower than that of neutral vacancies. Octahedral rotations $$({\mathrm{a}}^{0}{\mathrm{a}}^{0}{\mathrm{c}}^{{-}})$$ in the superlattices have a significant effect on $${E}_{\mathrm{v}}$$, increasing the formation energy of vacancies located near the interface but decreasing the formation energy of the oxygen vacancies located in the bulk-like regions of the STO and PTO constituent parts. The formation-energy variations among different layers are found to be primarily caused by the difference in the local relaxation at each layer. Finally, these fundamental insights into the defect stability in perovskite superlattices can be used to tune defect properties by controlling the constituent materials of superlattices and interface engineering.
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [2] ;  [4] ;  [5]
  1. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science. Computational Science and Engineering Division
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science
  5. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering. Joint Inst. for Advanced Materials
Publication Date:
Grant/Contract Number:
AC05-00OR22725; AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Physical Review Materials
Additional Journal Information:
Journal Volume: 2; Journal Issue: 6; Journal ID: ISSN 2475-9953
Publisher:
American Physical Society (APS)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); ORNL Laboratory Directed Research and Development (LDRD) Program; The Univ. of Tennessee (UT) Science Alliance Joint Directed Research and Development Program (United States)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; crystal defects; ferroelectrics; superlattices
OSTI Identifier:
1460196
Alternate Identifier(s):
OSTI ID: 1457079

Zhang, Lipeng, Bredeson, Isaac, Birenbaum, Axiel Y., Kent, P. R. C., Cooper, Valentino R., Ganesh, P., and Xu, Haixuan. Oxygen vacancy formation energies in PbTiO3/SrTiO3 superlattice. United States: N. p., Web. doi:10.1103/PhysRevMaterials.2.064409.
Zhang, Lipeng, Bredeson, Isaac, Birenbaum, Axiel Y., Kent, P. R. C., Cooper, Valentino R., Ganesh, P., & Xu, Haixuan. Oxygen vacancy formation energies in PbTiO3/SrTiO3 superlattice. United States. doi:10.1103/PhysRevMaterials.2.064409.
Zhang, Lipeng, Bredeson, Isaac, Birenbaum, Axiel Y., Kent, P. R. C., Cooper, Valentino R., Ganesh, P., and Xu, Haixuan. 2018. "Oxygen vacancy formation energies in PbTiO3/SrTiO3 superlattice". United States. doi:10.1103/PhysRevMaterials.2.064409.
@article{osti_1460196,
title = {Oxygen vacancy formation energies in PbTiO3/SrTiO3 superlattice},
author = {Zhang, Lipeng and Bredeson, Isaac and Birenbaum, Axiel Y. and Kent, P. R. C. and Cooper, Valentino R. and Ganesh, P. and Xu, Haixuan},
abstractNote = {The defect stability in a prototypical perovskite oxide superlattice consisting of ${\mathrm{SrTiO}}_{3}$ and ${\mathrm{PbTiO}}_{3}$ (STO/PTO) is determined by using first principles density functional theory calculations. Specifically, the oxygen vacancy formation energies ${E}_{\mathrm{v}}$ in the paraelectric and ferroelectric phases of a superlattice with four atomic layers of STO and four layers of PTO (4STO/4PTO) are determined and compared. The effects of charge state, octahedral rotation, polarization, and interfaces on ${E}_{\mathrm{v}}$ are examined in this paper. The formation energies vary layer by layer in the superlattices, with ${E}_{\mathrm{v}}$ being higher in the ferroelectric phase than that in the paraelectric phase. The two interfaces constructed in these oxide superlattices, which are symmetrically equivalent in the paraelectric systems, exhibit very different formation energies in the ferroelectric superlattices and this can be seen to be driven by the coupling of ferroelectric and rotational modes. At equivalent lattice sites, ${E}_{\mathrm{v}}$ of charged vacancies is generally lower than that of neutral vacancies. Octahedral rotations $({\mathrm{a}}^{0}{\mathrm{a}}^{0}{\mathrm{c}}^{{-}})$ in the superlattices have a significant effect on ${E}_{\mathrm{v}}$, increasing the formation energy of vacancies located near the interface but decreasing the formation energy of the oxygen vacancies located in the bulk-like regions of the STO and PTO constituent parts. The formation-energy variations among different layers are found to be primarily caused by the difference in the local relaxation at each layer. Finally, these fundamental insights into the defect stability in perovskite superlattices can be used to tune defect properties by controlling the constituent materials of superlattices and interface engineering.},
doi = {10.1103/PhysRevMaterials.2.064409},
journal = {Physical Review Materials},
number = 6,
volume = 2,
place = {United States},
year = {2018},
month = {6}
}

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