An Unusual Phase Transition Driven by Vibrational Entropy Changes in a Hybrid Organic–Inorganic Perovskite |
| |
| 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 |
| |
| Institution: | 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 |
| |
| 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. |
| |
| Keywords: | ab initio lattice dynamics calculations hybrid organic– inorganic perovskites phase transitions vibrational entropy |
|
|
