Abstract
In the present study, we extensively explored the phase stabilities and elastic behaviors of Cu2O with elevated pressures up to 29.3 GPa based on single-crystal X-ray diffraction measurements. The structural sequence of Cu2O is different than previously determined. Specifically, we have established that Cu2O under pressure, displays a cubic-tetragonal-monoclinic phase transition sequence, and a novel monoclinic high-pressure phase assigned to the P1a1 or P12/a1 space group was firstly observed. The monoclinic phase Cu2O exhibits anisotropic compression with axial compressibility βb > βc > βa in a ratio of 1.00:1.64:1.45. The obtained isothermal bulk modulus of cubic and monoclinic phase Cu2O are 125(2) and 41(6) GPa, respectively, and the KT0’ is fixed at 4. Our results provide new insights into the phase stability and elastic properties of copper oxides and chalcogenides at extreme conditions.
Highlights
The behaviors of transition metals and their oxides under high-temperature and high-pressure conditions have been studied extensively over a few decades, and knowledge about such material has important applications in physics, materials science, and engineering (Austin and Mott, 1970; Errandonea, 2006)
We report the phase transformations and elastic properties of Cu2O up to ∼30 GPa at room temperature, by using synchrotron-based single-crystal X-ray diffraction (XRD) with diamond anvil cell (DAC)
In this report we present the measured compressibilities and equations of states of these high pressure phases of Cu2O
Summary
The behaviors of transition metals and their oxides under high-temperature and high-pressure conditions have been studied extensively over a few decades, and knowledge about such material has important applications in physics, materials science, and engineering (Austin and Mott, 1970; Errandonea, 2006). Variations in physical properties and structural change of cuprous oxide Cu2O at extreme conditions have not been fully investigated. Cortona and Mebarki (2011) described the transition from cubic Cu2O to the CdI2-type structure (hexagonal, R-3m) at 10 GPa, while Feng et al (2017) suggested two phase transitions, one at 5 GPa (Pn-3m→R-3m) and the other at 12 GPa (R-3m→R-3m1). This is hard to reconcile with some experimental results on the pressure-induced structural transformations of Cu2O. What is more, Sinitsyn et al (2004) found a new hexagonal phase with lattice parameters of a 5.86 Å and c 18.78 Å at 21 GPa which was significantly different from those
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