Structural properties of defective (CH3NH3)2Cu(Cl1-xBrx)4 compounds
Alberto Martinelli1, Aniruddha Ray2, Ahmed L Abdelhady2
1SPIN-CNR, Corso Perrone 24, 16152 Genova, Italy.
This study reveals monoclinic crystal structures in (CH3NH3)2Cu(Cl1-xBrx)4 compounds, driven by Jahn-Teller distortion. Halogen vacancies and preferential bromine site occupancy were also observed.
Area of Science:
- Solid-state chemistry
- Crystallography
- Materials science
Background:
- Jahn-Teller distortion in Cu2+ ions influences crystal structures.
- Mixed halide perovskite compounds exhibit complex structural behaviors.
Purpose of the Study:
- To investigate the crystal structures of (CH3NH3)2Cu(Cl1-xBrx)4 compounds.
- To gain new insights into the structural properties and ordering phenomena.
Main Methods:
- Synchrotron powder X-ray diffraction.
- Pair distribution function analysis at room temperature.
Main Results:
- Monoclinic symmetry (space group P21/c) was identified, induced by cooperative orbital ordering from Jahn-Teller distortion.
- Significant vacancies were detected at halogen positions, differing from previous studies.
- Bromine atoms showed a preference for axial positions.
Conclusions:
- The study elucidates the structural characteristics of mixed halide copper(II) compounds.
- The findings highlight the impact of synthesis methods on defect formation and atomic site occupancy.
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