Wolański Łukasz, Metzelaars Marvin, van Leusen Jan, Kögerler Paul, Grochala Wojciech
Centre of New Technologies, University of Warsaw, S. Banacha 2c, 02-097, Warsaw, Poland.
Institute of Inorganic Chemistry, RWTH Aachen University, 52074, Aachen, Germany.
Chemistry. 2022 May 25;28(30):e202200712. doi: 10.1002/chem.202200712. Epub 2022 May 3.
Pressure-induced phase transitions of M Ag F 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 [AgF ] octahedra and their mutual approach through secondary Ag⋅⋅⋅F contacts. In stark contrast, only a single phase transition (tetragonal→triclinic) is predicted for CsAgF ; this is associated with substantial deformation of the Jahn-Teller-distorted first coordination sphere of Ag and association of the infinite [AgF ] chains into a polymeric sublattice. The phase transitions markedly decrease the coupling strength of intra-chain antiferromagnetic superexchange in MAgF hosts lattices.
首次从理论上预测了M = K、Rb、Cs的MAgF钙钛矿在高达100 GPa压力下的压力诱导相变。M = K和Rb的相变序列包括从正交晶系到单斜晶系再回到正交晶系的转变，这与角共享[AgF]八面体的无限链的逐渐弯曲以及它们通过Ag⋅⋅⋅F二次接触的相互靠近有关。与此形成鲜明对比的是，预测CsAgF只有一个相变（四方晶系→三斜晶系）；这与Ag的 Jahn-Teller 畸变的第一配位球的大量变形以及无限[AgF]链聚合成聚合物亚晶格有关。相变显著降低了MAgF主体晶格中链内反铁磁超交换的耦合强度。
