An Unusual Phase Transition Driven by Vibrational Entropy Changes in a Hybrid Organic–Inorganic Perovskite |
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| Authors: | Wenjuan Wei Prof. Wei Li Dr. Keith T. Butler Dr. Guoqiang Feng Prof. Christopher J. Howard Prof. Michael A. Carpenter Prof. Peixiang Lu Prof. Aron Walsh Prof. Anthony K. Cheetham |
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| Affiliation: | 1. School of Physics, Huazhong University of Science and Technology, Wuhan, China;2. ISIS Facility, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire, UK;3. School of Engineering, University of Newcastle, New South Wales, Australia;4. Department of Earth Sciences, University of Cambridge, Cambridge, UK;5. Laboratory of Optical Information Technology, Wuhan Institute of Technology, Wuhan, China;6. Department of Materials, Imperial College London, Royal School of Mines, London, UK;7. Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, UK |
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| Abstract: | The driving forces for the phase transitions of ABX3 hybrid organic–inorganic perovskites have been limited to the octahedral tilting, order–disorder, and displacement. Now, a complex structural phase transition has been explored in a HOIP, [CH3NH3][Mn(N3)3], based on structural characterizations and ab initio lattice dynamics calculations. This unusual first‐order phase transition between two ordered phases at about 265 K is primarily driven by changes in the collective atomic vibrations of the whole lattice, along with concurrent molecular displacements and an unusual octahedral tilting. A significant entropy difference (4.35 J K?1 mol?1) is observed between the low‐ and high‐temperature structures induced by such atomic vibrations, which plays a main role in driving the transition. This finding offers an alternative pathway for designing new ferroic phase transitions and related physical properties in HOIPs and other hybrid crystals. |
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| Keywords: | ab initio lattice dynamics calculations hybrid organic– inorganic perovskites phase transitions vibrational entropy |
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