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Negative thermal expansion in high pressure layered perovskite Ca2GeO4

Chen, Wei-Tin, Ablitt, Chris, Bristowe, Nicholas C., Mostof, Arash A., Saito, Takashi, Shimakawa, Yuichi, Senn, Mark S. (2019) Negative thermal expansion in high pressure layered perovskite Ca2GeO4. Chemical Communications, 55 (20). pp. 2984-2987. ISSN 1359-7345. E-ISSN 1364-548X. (doi:10.1039/c8cc09614g)

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We report the high pressure synthesis of a layered perovskite Ca2GeO4 which is found to have the Ruddlesden–Popper structure with I41/acd symmetry. Consonant with our recent predictions [Ablitt et al., npj Computational Materials, 2017, 3, 44], the phase displays pronounced uniaxial negative thermal expansion over a large temperature range. Negative thermal expansion that persists over a large temperature range is very unusual in the perovskite structure, and its occurrence in this instance can be understood to arise due to both soft lattice vibrations associated with a phase competition and the unusually compliant nature of this structure, which effectively couples thermal expansion in the layer plane to lattice contractions perpendicular to the layering direction via a “corkscrew” mechanism.

Item Type: Article
DOI/Identification number: 10.1039/c8cc09614g
Subjects: Q Science > QD Chemistry
Divisions: Faculties > Sciences > School of Physical Sciences > Functional Materials Group
Depositing User: Nicholas Bristowe
Date Deposited: 23 Jan 2019 13:03 UTC
Last Modified: 12 Jul 2019 10:55 UTC
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