CHEMICAL EXPANSIVITY IN CERAMIC OXYGEN TRANSPORT MATERIALS

CHEMICAL EXPANSIVITY IN CERAMIC OXYGEN TRANSPORT MATERIALS

Bibliographic Details
Main Author: Cai, Andrew
Language:English
Published: Case Western Reserve University School of Graduate Studies / OhioLINK 2020
Subjects:
Materials Science
Engineering
Oxygen transport membranes
perovskite
reduce
chemical strain
chemical expansion
mixed electronic ionic conducting
ceramic
methane reforming
syngas
Online Access:http://rave.ohiolink.edu/etdc/view?acc_num=case159439738367673
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spelling ndltd-OhioLink-oai-etd.ohiolink.edu-case1594397383676732021-08-03T07:15:41Z CHEMICAL EXPANSIVITY IN CERAMIC OXYGEN TRANSPORT MATERIALS Cai, Andrew Materials Science Engineering Oxygen transport membranes perovskite reduce chemical strain chemical expansion mixed electronic ionic conducting ceramic methane reforming syngas Chemical expansion of eight lanthanum strontium ferrite (LSF)-based oxygen transport materials (four purchased, four synthesized) was assessed isothermally at 800 °C, 900 °C, and 1,000 °C at oxygen potentials from 10<sup>-0.678</sup> atm (air) to 10<sup>-20.3</sup>–10<sup>-15.9</sup> atm (depending on temperature). The following compositions were tested: (La<sub>0.60</sub>Sr<sub>0.40</sub>)<sub>0.995</sub> Co<sub>0.20</sub>Fe<sub>0.80</sub>O<sub>3-δ</sub>, (La<sub>0.80</sub>Sr<sub>0.20</sub>)<sub>0.95</sub>FeO<sub>3-δ</sub>, (La<sub>0.20</sub>Sr<sub>0.80</sub>) Cr<sub>0.20</sub>Fe<sub>0.80</sub>O<sub>3-δ</sub>, (La<sub>0.20</sub>Sr<sub>0.80</sub>) Co<sub>0.10</sub>Cr<sub>0.20</sub>Fe<sub>0.70</sub>O<sub>3-δ</sub>, (La<sub>0.50</sub>Sr<sub>0.50</sub>)Cr<sub>0.20</sub>Fe<sub>0.80</sub>O<sub>3-δ</sub>, (La<sub>0.20</sub>Sr<sub>0.80</sub>) Co<sub>0.10</sub>Cr<sub>0.10</sub>Fe<sub>0.80</sub>O<sub>3-δ</sub>, (La<sub>0.20</sub>Sr<sub>0.80</sub>)Co<sub>0.10</sub>Cr<sub>0.10</sub>Mg<sub>0.05</sub>Fe<sub>0.75</sub>O<sub>3-δ</sub>, and (La<sub>0.50</sub>Sr<sub>0.50</sub>) Cr<sub>0.20</sub>Mg<sub>0.05</sub>Fe<sub>0.75</sub>O<sub>3-δ</sub>. Powder synthesis utilized aqueous nitrate solutions with malic acid added as a complexing agent. These exhibited good agreement with their target compositions. All eight materials sintered to ≥95% density in 16 hours at 1250–1350 °C. At the lowest partial pressure of oxygen (10<sup>-20.3</sup>, 10<sup>-17.9</sup>, 10<sup>-15.9</sup>) at their respective isothermal temperatures (800 °C, 900 °C, 1000 °C), three compositions demonstrated the lowest chemical expansion: (La<sub>0.60</sub>Sr<sub>0.40</sub>)<sub>0.995</sub> Co<sub>0.20</sub>Fe<sub>0.80</sub>O<sub>3-δ</sub>, (La<sub>0.20</sub>Sr<sub>0.80</sub>) Cr<sub>0.20</sub>Fe<sub>0.80</sub>O<sub>3-δ</sub>, and (La<sub>0.20</sub>Sr<sub>0.80</sub>)Co<sub>0.10</sub>Cr<sub>0.10</sub>Mg<sub>0.05</sub>Fe<sub>0.75</sub>O<sub>3-δ</sub>. Among these materials, (La<sub>0.60</sub>Sr<sub>0.40</sub>)<sub>0.995</sub> Co<sub>0.20</sub>Fe<sub>0.80</sub>O<sub>3-δ</sub> had a higher coefficient of chemical expansion compared to (La<sub>0.20</sub>Sr<sub>0.80</sub>) Cr<sub>0.20</sub>Fe<sub>0.80</sub>O<sub>3-δ</sub>, which is attributed to chromium being less reducible and therefore causing less lattice distortion compared to cobalt. It was concluded that (La<sub>0.60</sub>Sr<sub>0.40</sub>)<sub>0.995</sub> Co<sub>0.20</sub>Fe<sub>0.80</sub>O<sub>3-δ</sub> had low chemical expansion due to the A-site deficiency, and both (La<sub>0.20</sub>Sr<sub>0.80</sub>) Cr<sub>0.20</sub>Fe<sub>0.80</sub>O<sub>3-δ</sub> and (La<sub>0.20</sub>Sr<sub>0.80</sub>)Co<sub>0.10</sub>Cr<sub>0.10</sub>Mg<sub>0.05</sub>Fe<sub>0.75</sub>O<sub>3-δ</sub> due to their less reducible chromium and magnesium content. 2020-08-27 English text Case Western Reserve University School of Graduate Studies / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=case159439738367673 http://rave.ohiolink.edu/etdc/view?acc_num=case159439738367673 unrestricted This thesis or dissertation is protected by copyright: some rights reserved. It is licensed for use under a Creative Commons license. Specific terms and permissions are available from this document's record in the OhioLINK ETD Center.
collection NDLTD
language English
sources NDLTD
topic Materials Science
Engineering
Oxygen transport membranes
perovskite
reduce
chemical strain
chemical expansion
mixed electronic ionic conducting
ceramic
methane reforming
syngas
spellingShingle Materials Science
Engineering
Oxygen transport membranes
perovskite
reduce
chemical strain
chemical expansion
mixed electronic ionic conducting
ceramic
methane reforming
syngas
Cai, Andrew
CHEMICAL EXPANSIVITY IN CERAMIC OXYGEN TRANSPORT MATERIALS
author Cai, Andrew
author_facet Cai, Andrew
author_sort Cai, Andrew
title CHEMICAL EXPANSIVITY IN CERAMIC OXYGEN TRANSPORT MATERIALS
title_short CHEMICAL EXPANSIVITY IN CERAMIC OXYGEN TRANSPORT MATERIALS
title_full CHEMICAL EXPANSIVITY IN CERAMIC OXYGEN TRANSPORT MATERIALS
title_fullStr CHEMICAL EXPANSIVITY IN CERAMIC OXYGEN TRANSPORT MATERIALS
title_full_unstemmed CHEMICAL EXPANSIVITY IN CERAMIC OXYGEN TRANSPORT MATERIALS
title_sort chemical expansivity in ceramic oxygen transport materials
publisher Case Western Reserve University School of Graduate Studies / OhioLINK
publishDate 2020
url http://rave.ohiolink.edu/etdc/view?acc_num=case159439738367673
work_keys_str_mv AT caiandrew chemicalexpansivityinceramicoxygentransportmaterials
_version_ 1719457388157730816

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