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Controlling thermal expansion and phase transitions in Ca1−xSrxMnO3−δ by Sr-content

Klaas, Lena and Pein, Mathias and Mechnich, Peter and Francke, Alexander and Giasafakis, Dimitra and Kriechbaumer, Dorottya and Agrafiotis, Christos and Roeb, Martin and Sattler, Christian (2022) Controlling thermal expansion and phase transitions in Ca1−xSrxMnO3−δ by Sr-content. Physical Chemistry Chemical Physics, 45 (24), pp. 27976-27988. Royal Society of Chemistry. doi: 10.1039/D2CP04332G. ISSN 1463-9076.

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Official URL: https://pubs.rsc.org/en/content/articlelanding/2022/CP/D2CP04332G


Perovskite oxides of the general formula ABO3−δ, with A and B being metal cations, present themselves in various crystal structures that originate from a distorted ideal cubic perovskite. Understanding how composition, temperature, atmosphere and reduction extent of these non-stoichiometric redox materials induce structural changes on an atomic, as well as macroscopic, level is crucial to transfer newly developed materials to industrial scale applications in the redox-based energy conversion sector. Herein, Ca1−xSrxMnO3−δ (x ∈ [0,0.2]) and its micro- and macroscopic structural changes at elevated temperatures and varying oxygen partial pressure are analyzed by means of in situ high temperature XRD, DSC and dilatometry. Results are expanded by room temperature XRD of compositions with higher Sr-content up to x = 0.4. By adjusting the Sr-content, the formed crystal structure can be governed and thermal expansion can be impacted beneficially in the context of future applications utilizing monolithic structures. Phase transitions from orthorhombic to cubic were found to shift from 900 °C to 830 °C under air and to even lower temperatures under 1% O2 atmosphere. Small amounts of Sr-content (5–10%) stabilize the macroscopic structural integrity by improving the reversibility of the cyclic thermal expansion and contraction in a 1% O2 atmosphere. However, at Sr-contents of 20% an increased irreversible residual expansion within each thermal cycle becomes apparent and shows that such improvements do not follow a linear dependency with Sr-content, but most benefits in this context can be found at Sr-contents below 20%. The results demonstrate the sensitivity of such materials micro- and macroscopic characteristics to composition. In the context of utilization of monolithic structures, fabricated entirely from Ca1−xSrxMnO3−δ, in thermochemical or thermoelectric applications, the results have considerable significance as minor A-site Sr-substitution can substantially improve macroscopic stability of monolithic structures over multiple thermal cycles. Besides the often solely regarded thermodynamic characteristic, this work demonstrates the importance to consider the impact of composition on structural behavior in materials design processes including perovskites for thermochemical applications.

Item URL in elib:https://elib.dlr.de/193422/
Document Type:Article
Title:Controlling thermal expansion and phase transitions in Ca1−xSrxMnO3−δ by Sr-content
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Klaas, LenaUNSPECIFIEDhttps://orcid.org/0000-0003-0671-2335UNSPECIFIED
Pein, MathiasUNSPECIFIEDhttps://orcid.org/0000-0002-2796-1229UNSPECIFIED
Mechnich, PeterUNSPECIFIEDhttps://orcid.org/0000-0003-4689-8197UNSPECIFIED
Kriechbaumer, DorottyaUNSPECIFIEDhttps://orcid.org/0000-0001-7183-6401UNSPECIFIED
Agrafiotis, ChristosUNSPECIFIEDhttps://orcid.org/0000-0002-7140-9642UNSPECIFIED
Roeb, MartinUNSPECIFIEDhttps://orcid.org/0000-0002-9813-5135UNSPECIFIED
Sattler, ChristianUNSPECIFIEDhttps://orcid.org/0000-0002-4314-1124UNSPECIFIED
Date:14 November 2022
Journal or Publication Title:Physical Chemistry Chemical Physics
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
Page Range:pp. 27976-27988
Publisher:Royal Society of Chemistry
Keywords:Perovskite oxides, structural behavior, redox-based energy conversion sector
HGF - Research field:Energy
HGF - Program:Materials and Technologies for the Energy Transition
HGF - Program Themes:Chemical Energy Carriers
DLR - Research area:Energy
DLR - Program:E SW - Solar and Wind Energy
DLR - Research theme (Project):E - Solar Fuels
Location: Jülich , Köln-Porz
Institutes and Institutions:Institute of Future Fuels
Institute of Future Fuels > Solar-Chemical Process Development
Institute of Materials Research
Institute of Materials Research > Structural and Functional ceramics
Deposited By: Bülow, Mark
Deposited On:30 Jan 2023 07:25
Last Modified:30 Jan 2023 10:26

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