AUTHOR=Qin Fei , Zhang Dongzhou , Qin Shan 

TITLE=High Pressure Behaviors and a Novel High-Pressure Phase of Cuprous Oxide Cu2O

JOURNAL=Frontiers in Earth Science

VOLUME=9

YEAR=2021

URL=https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2021.740685

DOI=10.3389/feart.2021.740685

ISSN=2296-6463

ABSTRACT=<p>In the present study, we extensively explored the phase stabilities and elastic behaviors of Cu<sub>2</sub>O with elevated pressures up to 29.3 GPa based on single-crystal X-ray diffraction measurements. The structural sequence of Cu<sub>2</sub>O is different than previously determined. Specifically, we have established that Cu<sub>2</sub>O under pressure, displays a cubic-tetragonal-monoclinic phase transition sequence, and a novel monoclinic high-pressure phase assigned to the <italic>P</italic>1<italic>a</italic>1 or <italic>P</italic>12/<italic>a</italic>1 space group was firstly observed. The monoclinic phase Cu<sub>2</sub>O exhibits anisotropic compression with axial compressibility <italic>β</italic><sub><italic>b</italic></sub> &gt; <italic>β</italic><sub><italic>c</italic></sub> &gt; <italic>β</italic><sub><italic>a</italic></sub> in a ratio of 1.00:1.64:1.45. The obtained isothermal bulk modulus of cubic and monoclinic phase Cu<sub>2</sub>O are 125(2) and 41(6) GPa, respectively, and the <italic>K</italic><sub><italic>T</italic>0</sub>’ is fixed at 4. Our results provide new insights into the phase stability and elastic properties of copper oxides and chalcogenides at extreme conditions.</p>