High-pressure behaviour of Prussian blue analogues: interplay of hydration, Jahn-Teller distortions and vacancies

Hanna L B Boström; Ines E Collings; Andrew B Cairns; Carl P Romao; Andrew L Goodwin

doi:10.1039/c8dt04463e

High-pressure behaviour of Prussian blue analogues: interplay of hydration, Jahn-Teller distortions and vacancies

Dalton Trans. 2019 Feb 7;48(5):1647-1655. doi: 10.1039/c8dt04463e. Epub 2018 Dec 14.

Authors

Hanna L B Boström¹, Ines E Collings², Andrew B Cairns³, Carl P Romao⁴, Andrew L Goodwin¹

Affiliations

¹ Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR, UK. andrew.goodwin@chem.ox.ac.uk.
² European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France.
³ European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000 Grenoble, France and Department of Materials, Imperial College London, Royal School of Mines, Exhibition Road, SW7 2AZ, UK.
⁴ Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR, UK. andrew.goodwin@chem.ox.ac.uk and Institut für Anorganische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany.

PMID: 30548036
DOI: 10.1039/c8dt04463e

Abstract

We report a high-pressure crystallographic study of four hydrated Prussian blue analogues: M[Pt(CN)₆] and M[Co(CN)₆]_0.67 (M = Mn²⁺, Cu²⁺) in the range 0-3 GPa. Mn[Co(CN)₆]_0.67 was studied by single-crystal X-ray diffraction, whereas the other systems were only available in polycrystalline form. The Mn-containing compounds undergo pressure-induced phase transitions from Fm3[combining macron]m to R3[combining macron] at ∼1.0-1.5 GPa driven by cooperative tilting of the octahedral units. No phase transition was found for the orbitally disordered Cu[Co(CN)₆]_0.67 up to 3 GPa. Mn[Co(CN)₆]_0.67 is significantly softer than the other samples, with a bulk modulus of ∼14 GPa compared to ∼35 GPa of the powdered samples. The discrepant pressure responses are discussed in terms of the presence of structural defects, Jahn-Teller distortions, and hydration. The implications for the development of polar systems are reviewed based upon our high-pressure study.