ES22-Bujdak

Author: Bujdák, Radovan - Advanced Technologies Research Institute, Faculty of Materials Science and Technology in Trnava, Slovak University of Technology in Bratislava, 917 24 Trnava, Slovakia

Title: Exploring new phases in Ni-O binary system from ab initio

Abstract: The Ni-O binary system contains only one well known phase, namely NiO, although other stoichiometries such as Ni2O3 and Ni2O5 are perfectly viable but much less studied. Nickel sesquioxide, Ni2O3, also referred to as black nickel oxide is currently being increasingly used as a component for number of functional materials due to its photocatalytic activity [1]. However, the compound remains poorly characterized and its crystal structure, which is a crucial starting point for the understanding of relationship between structure and properties, remains unresolved [2]. On the other hand, nickel pentoxide Ni2O5 represents a completely unknown and unstudied phase. Nevertheless, both sesquioxides and pentoxides are common among other transition metals. For example, majority of 3d transition metals forms sesquioxides and early transition metals such as V, Nb, Ta form pentoxides that exhibit rich polymorphism with various level of structural complexity. Therefore, our study is dedicated to theoretical prediction of crystal structure and structure-related properties of Ni2O3 and Ni2O5 with the use of Density Functional Theory (DFT) and evolutionary algorithms (EA). First, we evaluate the fitness of the structure types commonly observed in sesquioxides and pentoxides of transition metals to accommodate the corresponding Ni oxide by means of DFT calculations. Next, we use DFT modelling in conjunction with EA to search for the global minimum structures [3]. We present the results of thorough spin-polarized DFT calculations (DFT, DFT+U and hybrid DFT) and EA search including crystal, electronic and magnetic structures and lattice dynamics.

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; PRACE FENIX Project fnxp070004 at TGCC high performance computing infrastructure, France.

References:
[1] Shaban, M., Abukhadra, M.R. & Hamd, Clean Techn Environ Policy 20, 13–28 (2018).
[2] P. S. Aggarwal and A. Goswami, National Chemical Laboratory 2-0770 (1961). [3] D. C. Lonie, E. Zurek, Computer Physics Communications 182, 372-387 (2011).

Other authors: Gašpárková, Michaela, Advanced Technologies Research Institute, Faculty of Materials Science and Technology in Trnava, Slovak University of Technology in Bratislava, 917 24 Trnava, Slovakia; Tokár, Kamil, Advanced Technologies Research Institute, Faculty of Materials Science and Technology in Trnava, Slovak University of Technology in Bratislava, 917 24 Trnava, Slovakia, Institute of Physics, Slovak Academy of Sciences, 845 11 Bratislava, Slovakia; Derzsi, Mariana, Advanced Technologies Research Institute, Faculty of Materials Science and Technology in Trnava, Slovak University of Technology in Bratislava, 917 24 Trnava, Slovakia