Abstract
By using optical absorption and Raman spectroscopy, we have investigated the effects of pressure in the structural, electronic, and vibrational properties of in the 0–20 GPa range. Our study has provided a complete characterization of the electronic and vibrational structures of in the low-pressure Pnma phase as a function of cell volume and the Cu-Cl bond length, . We have focused on the electronic structure in the Pnma phase, which is mainly related to the tetrahedral units distorted by the Jahn-Teller effect. The strong piezochromism of is caused by the opposite shift of the charge-transfer band gap and the d-d crystal-field transitions with pressure. The high-pressure structure of above 4.9 GPa yields structural transformations that we ascribe to a change of coordination around . 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.
2 More- Received 30 January 2019
- Revised 29 March 2019
DOI:https://doi.org/10.1103/PhysRevB.99.134106
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