Abstract
The hybrid perovskites are coordination frameworks with the same topology as the inorganic perovskites, but with properties driven by different chemistry, including host-framework hydrogen bonding. Like the inorganic perovskites, these materials exhibit many different phases, including structures with potentially exploitable functionality. However, their phase transformations under pressure are more complex and less well understood. We have studied the structures of manganese and cobalt guanidinium formate under pressure using single-crystal X-ray and powder neutron diffraction. Under pressure, these materials transform to a rhombohedral phase isostructural to cadmium guanidinium formate. This transformation accommodates the reduced cell volume while preserving the perovskite topology of the framework. Using density-functional theory calculations, we show that this behaviour is a consequence of the hydrogen-bonded network of guanidinium ions, which act as struts protecting the metal formate framework against compression within their plane. Our results demonstrate more generally that identifying suitable host-guest hydrogen-bonding geometries may provide a route to engineering hybrid perovskite phases with desirable crystal structures. This article is part of the theme issue 'Mineralomimesis: natural and synthetic frameworks in science and technology'.
| Original language | English |
|---|---|
| Article number | 20180227 |
| Journal | Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences |
| Volume | 377 |
| Issue number | 2149 |
| DOIs | |
| State | Published - 2019 |
| Externally published | Yes |
Funding
Data accessibility. The raw neutron data reported here are available from the ISIS data repository at DOIs 10.5286/ISIS.E.47628012 and 10.5286/ISIS.E.58447525. Single-crystal diffraction data in CIF format and full experimental and computational details are provided as electronic supplementary material. Authors’ contributions. Z.Y., G.C. and A.E.P. performed the synchrotron experiments; C.L.B., M.G.T, M.T.D. and A.E.P. performed the neutron experiments; A.F. performed the laboratory X-ray experiments and analysed the associated data. Z.Y. and A.E.P. analysed the synchrotron and neutron diffraction data. A.E.P. conceived the project, wrote the proposals for synchrotron and neutron beam time, performed the DFT calculations and wrote the first draft of the manuscript. All authors contributed to revising the data analysis and manuscript, and read and approved the final version. Competing interests. We declare we have no competing interests. Funding. We are grateful to ISIS Neutron and Muon Source and Diamond Light Source for the award of beam time and to the UK Materials and Molecular Modelling Hub for computational resources, which is partially funded by EPSRC (EP/P020194/1). Z.Y. and G.C. thank the Chinese Scholarships Council for scholarships. A.F. acknowledges financial support from the DFG, Germany, within priority program SPP1236 (project no. FR-2491/2-1) and from Goethe-Universität Frankfurt. A.E.P. thanks EPSRC for funding (EP/L024977/1). Acknowledgements. We gratefully acknowledge Björn Winkler (Goethe-Universität Frankfurt) for collaboration on preliminary experiments for this work; Nicholas Funnell (ISIS Neutron and Muon Source) and Viswanathan Mohandoss (QMUL) for assistance with the neutron experiments; Mark Warren and David Allan (Diamond Light Source) for assistance with the X-ray experiments; and Keith Refson (Royal Holloway, University of London) for helpful discussion about the DFT calculations. We are grateful to ISIS Neutron and Muon Source and Diamond Light Source for the award of beam time and to the UK Materials and Molecular Modelling Hub for computational resources, which is partially funded by EPSRC (EP/P020194/1). Z.Y. and G.C. thank the Chinese Scholarships Council for scholarships. A.F. acknowledges financial support from the DFG, Germany, within priority program SPP1236 (project no. FR-2491/2-1) and from Goethe-Universität Frankfurt. A.E.P. thanks EPSRC for funding (EP/L024977/1).
Keywords
- Coordination frameworks
- High pressure
- Hybrid perovskites
- Hydrogen bonding
- Phase transitions