Structural Phase Transitions and Magnetic Superexchange in M^I Ag^II F₃ Perovskites at High Pressure.

ABSTRACT: Pressure-induced phase transitions of M^I Ag^II F₃ 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 Ag^II 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.

SUBMITTER: Wolanski L 

PROVIDER: S-EPMC9320850 | biostudies-literature | 2022 May

REPOSITORIES: biostudies-literature