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Title: Density-functional study of the La 2Zr 2O 7 low-index surfaces

Abstract

We report that in order to explain the ability of lanthanum zirconate (La 2Zr 2O 7, LZ) and various doped forms of LZ to function as catalysts, an understanding of LZ surface structures is needed. Accordingly, certain LZ surfaces that are expected to be prevalent in prepared samples of LZ, namely, the low-index (001), (011), and (111) surfaces, are examined at the level of density-functional theory. All possible surface terminations of these surfaces formed by cleaving a perfect LZ crystal, termed ideal surface terminations, are considered, as well as several defective surface terminations of a given surface. Surface energies and surface free energies are computed, and surface phase diagrams (SPDs) of the (001), (011), and (111) surfaces are obtained. From these SPDs, the thermodynamically preferred surface termination of the (001), (011), or (111) surface is concluded to be nonideal over a large range of temperature and oxygen gas partial pressure conditions. This finding is unchanged if the SPDs are determined more accurately by taking into account certain vibrational contributions obtained from computed phonon dispersions. Additionally, a way to use results to characterize the surfaces of synthesized LZ crystallites is discussed, but the shapes or dimensions of the crystallites first needmore » to be obtained.« less

Authors:
 [1]; ORCiD logo [2]
  1. National Energy Technology Lab. (NETL), Morgantown, WV (United States)
  2. National Energy Technology Lab. (NETL), Pittsburgh, PA (United States)
Publication Date:
Research Org.:
National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV, and Albany, OR (United States)
Sponsoring Org.:
USDOE Office of Fossil Energy (FE)
OSTI Identifier:
1582394
Report Number(s):
NETL-PUB-22200
Journal ID: ISSN 0039-6028
Resource Type:
Accepted Manuscript
Journal Name:
Surface Science
Additional Journal Information:
Journal Volume: 689; Journal Issue: C; Journal ID: ISSN 0039-6028
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; La2Zr2O7; Pyrochlore oxide; Surface free energy; Density-functional theory

Citation Formats

Mantz, Yves A., and Duan, Yuhua. Density-functional study of the La2Zr2O7 low-index surfaces. United States: N. p., 2018. Web. doi:10.1016/j.susc.2018.04.010.
Mantz, Yves A., & Duan, Yuhua. Density-functional study of the La2Zr2O7 low-index surfaces. United States. doi:10.1016/j.susc.2018.04.010.
Mantz, Yves A., and Duan, Yuhua. Thu . "Density-functional study of the La2Zr2O7 low-index surfaces". United States. doi:10.1016/j.susc.2018.04.010. https://www.osti.gov/servlets/purl/1582394.
@article{osti_1582394,
title = {Density-functional study of the La2Zr2O7 low-index surfaces},
author = {Mantz, Yves A. and Duan, Yuhua},
abstractNote = {We report that in order to explain the ability of lanthanum zirconate (La2Zr2O7, LZ) and various doped forms of LZ to function as catalysts, an understanding of LZ surface structures is needed. Accordingly, certain LZ surfaces that are expected to be prevalent in prepared samples of LZ, namely, the low-index (001), (011), and (111) surfaces, are examined at the level of density-functional theory. All possible surface terminations of these surfaces formed by cleaving a perfect LZ crystal, termed ideal surface terminations, are considered, as well as several defective surface terminations of a given surface. Surface energies and surface free energies are computed, and surface phase diagrams (SPDs) of the (001), (011), and (111) surfaces are obtained. From these SPDs, the thermodynamically preferred surface termination of the (001), (011), or (111) surface is concluded to be nonideal over a large range of temperature and oxygen gas partial pressure conditions. This finding is unchanged if the SPDs are determined more accurately by taking into account certain vibrational contributions obtained from computed phonon dispersions. Additionally, a way to use results to characterize the surfaces of synthesized LZ crystallites is discussed, but the shapes or dimensions of the crystallites first need to be obtained.},
doi = {10.1016/j.susc.2018.04.010},
journal = {Surface Science},
number = C,
volume = 689,
place = {United States},
year = {2018},
month = {4}
}

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