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Local Structure and Dynamics in MPt(CN)6 Prussian Blue Analogues
Elodie A Harbourne1, Helena Barker1, Quentin Guéroult1
1Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR, U.K.
Chemistry of Materials : a Publication of the American Chemical Society
|June 17, 2024
Summary
Researchers studied local structure and dynamics in Prussian blue analogues using X-ray pair distribution function (PDF) and density functional theory (DFT). They identified correlated octahedra tilts as the key mechanism for negative thermal expansion (NTE).
Area of Science:
- Materials Science
- Solid-State Physics
- Crystallography
Background:
- Prussian blue analogues (PBAs) exhibit complex structural and dynamic properties.
- Understanding local structure and lattice dynamics is crucial for predicting material behavior, including negative thermal expansion (NTE).
Purpose of the Study:
- To investigate the local structure and dynamics in MPt(CN)6 Prussian blue analogues.
- To establish a direct link between local distortions observed via PDF and the lattice dynamics.
- To identify the atomic-level mechanisms responsible for NTE in these materials.
Main Methods:
- X-ray pair distribution function (PDF) measurements.
- Lattice dynamical calculations.
- Ab initio density functional theory (DFT) calculations.
- Development and application of a novel "interaction-space" PDF refinement approach.
Main Results:
- The "interaction-space" PDF refinement approach successfully yielded effective harmonic force constants.
- Experiment-derived low-energy phonon dispersion relations were approximated.
- Grüneisen parameters identified correlated tilts of coordination octahedra as the primary cause of NTE.
- DFT calculations corroborated the NTE mechanism identified through experimental data.
Conclusions:
- Correlated octahedra tilts are the dominant mechanism driving negative thermal expansion in MPt(CN)6 PBAs.
- The developed "interaction-space" PDF refinement approach provides a powerful tool for linking local structure to lattice dynamics.
- This study offers fundamental insights into the structure-property relationships of Prussian blue analogues.
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