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Title: A Combined Variable-Temperature Neutron Diffraction and Thermogravimetric Analysis Study on a Promising Oxygen Electrode, SrCo 0.9Nb 0.1O 3–δ, for Reversible Solid Oxide Fuel Cells

Abstract

The present study reported herein investigates the temperature–structure–stoichiometry relationship of a promising oxygen electrode SrCo 0.9Nb 0.1O 3-δ over a temperature (T) range from room temperature (RT) to 900 °C. The techniques employed are variable-temperature neutron diffraction (VTND) and thermogravimetric analysis (TGA). At $T$ < 75 °C, VTND reveals a tetragonal (P4/mmm) structure with a G-type magnetic ordering. Above 75 °C, the nucleus structure remains the same, while the magnetic ordering disappears. A phase transition from tetragonal ($P4/mmm$) to cubic ($$Pm\overline3m$$) is observed at 412 °C, where the two Co sites and three O sites in the $P4/mmm$ phase converge to one equivalent site, respectively. The phase transition temperature coincides with the peak temperature of oxygen uptake obtained by TGA. It is also observed that the Nb dopant has no preferred Co site to occupy. The oxygen vacancies are mostly located at the O3 site surrounding the Co2 site in the $P4/mmm$ structure. The intermediate-spin state of Co 3+ at the Co2 site is responsible for the observed distortions of CoO 6 octahedra, i.e., elongation of Co2O 6 octahedra and shortening of Co1O 6 octahedra along the c-axis, which is a phenomenon known as Jahn–Teller distortion. At high temperatures, large thermal displacement factor for O 2– is observed with high concentration of oxygen vacancies, providing a structural environment favorable to high O 2– conductivity in Nb-doped SrCoO 3-based oxygen electrode materials.

Authors:
 [1];  [1]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [2];  [1]; ORCiD logo [1]
  1. Univ. of South Carolina, Columbia, SC (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
Sponsoring Org.:
USDOE Advanced Research Projects Agency - Energy (ARPA-E); USDOE Office of Fossil Energy (FE); National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division
OSTI Identifier:
1607184
Grant/Contract Number:  
AC05-00OR22725; AR0000492; FE0023317l CBET-1464112
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
ACS Applied Materials and Interfaces
Additional Journal Information:
Journal Volume: 9; Journal Issue: 40; Journal ID: ISSN 1944-8244
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; neutron diffraction; thermogravimetric analysis; oxygen stoichiometry; oxidation-state; phase transition

Citation Formats

Yang, Tianrang, Wang, Jie, Chen, Yan, An, Ke, Ma, Dong, Vogt, Thomas, and Huang, Kevin. A Combined Variable-Temperature Neutron Diffraction and Thermogravimetric Analysis Study on a Promising Oxygen Electrode, SrCo0.9Nb 0.1O3–δ, for Reversible Solid Oxide Fuel Cells. United States: N. p., 2017. Web. doi:10.1021/acsami.7b08697.
Yang, Tianrang, Wang, Jie, Chen, Yan, An, Ke, Ma, Dong, Vogt, Thomas, & Huang, Kevin. A Combined Variable-Temperature Neutron Diffraction and Thermogravimetric Analysis Study on a Promising Oxygen Electrode, SrCo0.9Nb 0.1O3–δ, for Reversible Solid Oxide Fuel Cells. United States. doi:10.1021/acsami.7b08697.
Yang, Tianrang, Wang, Jie, Chen, Yan, An, Ke, Ma, Dong, Vogt, Thomas, and Huang, Kevin. Mon . "A Combined Variable-Temperature Neutron Diffraction and Thermogravimetric Analysis Study on a Promising Oxygen Electrode, SrCo0.9Nb 0.1O3–δ, for Reversible Solid Oxide Fuel Cells". United States. doi:10.1021/acsami.7b08697. https://www.osti.gov/servlets/purl/1607184.
@article{osti_1607184,
title = {A Combined Variable-Temperature Neutron Diffraction and Thermogravimetric Analysis Study on a Promising Oxygen Electrode, SrCo0.9Nb 0.1O3–δ, for Reversible Solid Oxide Fuel Cells},
author = {Yang, Tianrang and Wang, Jie and Chen, Yan and An, Ke and Ma, Dong and Vogt, Thomas and Huang, Kevin},
abstractNote = {The present study reported herein investigates the temperature–structure–stoichiometry relationship of a promising oxygen electrode SrCo0.9Nb0.1O3-δ over a temperature (T) range from room temperature (RT) to 900 °C. The techniques employed are variable-temperature neutron diffraction (VTND) and thermogravimetric analysis (TGA). At $T$ < 75 °C, VTND reveals a tetragonal (P4/mmm) structure with a G-type magnetic ordering. Above 75 °C, the nucleus structure remains the same, while the magnetic ordering disappears. A phase transition from tetragonal ($P4/mmm$) to cubic ($Pm\overline3m$) is observed at 412 °C, where the two Co sites and three O sites in the $P4/mmm$ phase converge to one equivalent site, respectively. The phase transition temperature coincides with the peak temperature of oxygen uptake obtained by TGA. It is also observed that the Nb dopant has no preferred Co site to occupy. The oxygen vacancies are mostly located at the O3 site surrounding the Co2 site in the $P4/mmm$ structure. The intermediate-spin state of Co3+ at the Co2 site is responsible for the observed distortions of CoO6 octahedra, i.e., elongation of Co2O6 octahedra and shortening of Co1O6 octahedra along the c-axis, which is a phenomenon known as Jahn–Teller distortion. At high temperatures, large thermal displacement factor for O2– is observed with high concentration of oxygen vacancies, providing a structural environment favorable to high O2– conductivity in Nb-doped SrCoO3-based oxygen electrode materials.},
doi = {10.1021/acsami.7b08697},
journal = {ACS Applied Materials and Interfaces},
issn = {1944-8244},
number = 40,
volume = 9,
place = {United States},
year = {2017},
month = {10}
}

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