Pressure-induced closure of the jahn-teller distortion in Rb₂CuCl₄(H₂O)₂

This work investigates the pressure-induced variation of the local structure around Cu²⁺ as well as the crystal structure in Rb₂CuCl₄(H₂O)₂ through XAS and XRD techniques. The application of pressure induces a structural change in the Jahn-Teller (JT) [Formula: See Text] complex from axially elongated to compressed. This change leads to the closing of the 2D JT distortion related to the four in-plane Cl⁻ 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 favours the occurrence of such a local structural transition below the metallization pressure. The results are compared with recent pressure experiments on A₂CuCl₄ systems.

Keywords:

• Cu2+
• Cucl4(H2O)2
• Jahn-Teller Effect
• Xrd And Xas Under Pressure
• Layer Perovskite