Pressure-induced closure of the Jahn-Teller distortion in Rb{sub}2CuCl{sub}(H{sub}2O){sub}2

摘要

This work investigates the pressure-induced variation of the local structure around Cu{sup}(2+) as well as the crystal structure in Rb{sub}2CuCl{sub}4(H{sub}2O){sub}2 through XAS and XRD techniques. The application of pressure induces a structural change in the Jahn-Teller (JT) CuCl{sub}4(H{sub}2O){sub}2{sup}(2-) complex from axially elongated to compressed. This change leads to the closing of the 2D JT distortion related to the four in-plane Cl{sup}- ligands, which are responsible for the antiferrodistortive structure displayed by the crystal. It is shown that the presence of water ligands enhances a JT release. Their associated axial ligand-field favors the occurrence of such a local structural transition below the metallization pressure. The results are compared with recent pressure experiments on A{sub}2CuCl{sub}4 systems.