High-pressure phase transitions of Cu 2 O

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

“…2.74, 2.42, 2.30, 2.03, 1.97, 1.76 Å and so on) and the d values of these peaks are totally different from those previous patterns, suggesting that the Cu 2 O undergoes a reconstructive phase transition, and with further compression to the highest pressure, the structure can persist and no other transition was observed (Figure 1A). We have compared our patterns with some predicted hexagonal high-pressure phases of Cu 2 O based on previous ab initio calculation and measurement results, but none of the predicted structures matches our measured diffraction pattern (Werner and Hochheimer, 1982;Cortona and Mebarki, 2011;Liu et al, 2014;Feng et al, 2017). In this case, the high quality data allow us to determine the crystal structure of the new high-pressure phase of Cu 2 O.…”

“…Some diffraction peaks become fainter at higher angle, making it more difficult to determine the peak positions exactly (Figure 1B). We compared our integrated data of the high-pressure phase with previous studies but did not find any compatible structures (Werner and Hochheimer, 1982;Cortona and Mebarki, 2011;Feng et al, 2017).…”

“…The high-pressure behavior of cuprous oxide Cu 2 O has attracted broad interests due to their various structures at different P-T conditions and its potential applications. Several previous studies have been published which focus on the phase transitions and decompositions of Cu 2 O and its thermodynamic properties as well (Machon et al, 2003;Sinitsyn et al, 2004;Cortona and Mebarki, 2011;Liu et al, 2014;Feng et al, 2017). However, these previous results were unclear about the high-pressure crystal structure of Cu 2 O (tetragonal or hexagonal phase) and it is obvious that a large discrepancy of transformation pressure between the cubic and high-pressure phases existed between literatures.…”

“…Cu 2 O crystalizes in a simple cubic Bravais lattice with space group Pn-3m under normal thermodynamic conditions, while it has numerous structure forms at extreme conditions (Machon et al, 2003;Cortona and Mebarki, 2011;Feng et al, 2017). Most of previous studies have focused on the structural variations under high P-T conditions based on first-principles calculations.…”

“…Most of previous studies have focused on the structural variations under high P-T conditions based on first-principles calculations. Cortona and Mebarki (2011) described the transition from cubic Cu 2 O to the CdI 2 -type structure (hexagonal, R-3m) at 10 GPa, while Feng et al (2017) suggested two phase transitions, one at 5 GPa and the other at 12 GPa (R-3m→R-3m1). However, this is hard to reconcile with some experimental results on the pressure-induced structural transformations of Cu 2 O.…”