Origin of the piezochromism in Cs2CuCl4: Electron-phonon and crystal-structure correlations

Article

关键词: RAMAN-SCATTERING;    PRESSURE;    COMPLEXES;    SPECTRA;    PLANAR;   

DOI  :  10.1103/PhysRevB.99.134106

来源: SCIE

【 摘 要 】

By using optical absorption and Raman spectroscopy, we have investigated the effects of pressure in the structural, electronic, and vibrational properties of Cs2CuCl4 in the 0-20 GPa range. Our study has provided a complete characterization of the electronic and vibrational structures of Cs2CuCl4 in the low-pressure Pnma phase as a function of cell volume and the Cu-Cl bond length, RCu-Cl. We have focused on the electronic structure in the Pnma phase, which is mainly related to the tetrahedral CuCl42- units distorted by the Jahn-Teller effect. The strong piezochromism of Cs2CuCl4 is caused by the opposite shift of the charge-transfer band gap and the Cu2+ d-d crystal-field transitions with pressure. The high-pressure structure of Cs2CuCl4 above 4.9 GPa yields structural transformations that we ascribe to a change of coordination around Cu2+. The high-pressure phase appears largely amorphized, therefore any structural information from x-ray diffraction is ruled out. Here we use electronic and vibrational probes to get inside the structural information.

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