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Negative thermal expansion in high pressure layered perovskite Ca2GeO4

    Home Ablitt Negative thermal expansion in high pressure layered perovskite Ca2GeO4
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    Negative thermal expansion in high pressure layered perovskite Ca2GeO4

    By Mark | Ablitt, Publications | 0 comment | 25 February, 2019 | 0

    Wei-Tin Chen, Chris Ablitt, Nicholas C. Bristowe, Arash A. Mostofi, Takashi Saito, Yuichi Shimakawaf and Mark S. Senn .  Chem. Commun., 2019, Advance Article  10.1039/C8CC09614G

    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 Comput. Mater., 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.

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