Binary copper oxides [Cu-O] are enjoying large attention from a broad scientific community due to their electronic and optical properties that render them promising candidates for photovoltaics and for all-oxide electronics. They are excellent light absorbers across the visible energy range, exhibit excellent stability, are non-toxic and simply manufactured. Furthermore, they give rise to a vast family of semiconductors and superconductors, and as such belong to the most studied transition metal oxides [1,2]. Interestingly, only three binary phases are known Cu₂O, Cu^IIO and Cu^I₂Cu^II₂O₃ although there are many indications scattered across the known literature that suggest formation of various other stoichiometries [3,4]. Also, no binary oxide with Cu^III is known even though it is perfectly valid oxidation state of copper. The recognized technological potential of copper oxides as well as our chemical curiosity urges us for their immediate exploration. In this contribution we provide new theoretical evidence for phase diversity among the binary copper oxides by addressing the ‘suspected’ stoichiometries and oxidation states with various Density Functional Theory approaches. We take advantage of the structural diversity observed in the binary and ternary transition metal oxides and evaluate accessibility of their crystal structures to various copper oxidation states, electronic configurations (high-spin, low-spin), ionic sizes and shapes in hypothetical binary copper oxides obtained by M --> Cu substitution. We will present details of calculated crystal, electronic and magnetic structure and vibrational spectra for the most interesting cases.

Acknowledgement: The European Regional Development Fund, Research and Innovation Operational Programme, for project No. ITMS2014+: 313011W085; Scientific Grant Agency of the Slovak Republic, grant No. VG 1/0223/19; the Slovak Research and Development Agency, grant No. APVV-18-0168; Aurel supercomputing infrastructure in CC of Slovak Academy of Sciences acquired in projects ITMS 26230120002 and 26210120002 funded by ERDF.

References:

[1] B. K. Meyer et al., Phys. Status Solidi B, 249, 8, 1487 (2012).

[2] T. K. S. Wong, S. Zhuk, S. Masudy-Panah, G. K. Dalapati, Materials, 9, 271 (2016).

[3] D.L. Cockea et al., Vacuum, 79, 71 (2005).

[4] G.K. Moiseev and A.L. Ivanovskii, Neorganicheskie Materialy, 42, 700 (2006).