Structural Phase Transitions and Magnetic Superexchange in MIAgIIF3 Perovskites at High Pressure** |
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Authors: | Dr Łukasz Wolański Dr Marvin Metzelaars Dr Jan van Leusen Prof Paul Kögerler Prof Wojciech Grochala |
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Institution: | 1. Centre of New Technologies, University of Warsaw, S. Banacha 2c, 02-097 Warsaw, Poland;2. Institute of Inorganic Chemistry, RWTH Aachen University, 52074 Aachen, Germany |
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Abstract: | Pressure-induced phase transitions of MIAgIIF3 perovskites (M=K, Rb, Cs) have been predicted theoretically for the first time for pressures up to 100 GPa. The sequence of phase transitions for M=K and Rb consists of a transition from orthorhombic to monoclinic and back to orthorhombic, associated with progressive bending of infinite chains of corner-sharing AgF6]4− octahedra and their mutual approach through secondary Ag⋅⋅⋅F contacts. In stark contrast, only a single phase transition (tetragonal→triclinic) is predicted for CsAgF3; this is associated with substantial deformation of the Jahn–Teller-distorted first coordination sphere of AgII and association of the infinite AgF6]4− chains into a polymeric sublattice. The phase transitions markedly decrease the coupling strength of intra-chain antiferromagnetic superexchange in MAgF3 hosts lattices. |
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Keywords: | fluorides high pressure magnetic superexchange perovskites phase transitions silver |
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