Compressibility Studies of Copper Selenides Obtained by Cation Exchange Reaction Revealing the New CsCl Phase.

Banerjee, Progna; Prakapenka, Vitali B; Chariton, Stella; Shevchenko, Elena V · Nano Lett · 2024

basic_science · Level V

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Abstract

In this study, we conducted a high-pressure investigation of Cu<sub>2-<i>x</i></sub>Se nanostructures with pyramid- and plate-like morphologies, created through cation exchange from zinc-blende CdSe nanocrystals and wurtzite CdSe nanoplatelets respectively. Using a diamond anvil cell setup at the APS synchrotron, we observed the phase transitions in the Cu<sub>2-<i>x</i></sub>Se nanostructures up to 40 GPa, identifying a novel CsCl-type lattice with <i>Pm</i>3̅<i>m</i> symmetry above 4 GPa. This CsCl-type structure, previously unreported in copper selenides, was partially retained after decompression. Our results indicate that the initial crystalline structure of CdSe does not affect the stability of Cu<sub>2-<i>x</i></sub>Se nanostructures formed via cation exchange. Both morphologies of Cu<sub>2-<i>x</i></sub>Se sintered under compression, potentially contributing to the stabilization of the high-pressure phase through interfacial defects. These findings are significant for discovering new phases with potential applications in future technologies.