Search

Material science faces a significant problem in the search for new two-dimensional materials for electrical, gas sensing, and catalytic applications. The search for novel two-dimensional tin oxide materials was carried out in this study using an evolutionary structure prediction algorithm and ab initio approaches. The results of evolutionary search calculations reveal stable Sn2O3, SnO2, SnO, and Sn3O4and metastable Sn3O5structures. Here, Sn2O3is a novel structure with a tetragonal symmetry that has been confirmed to be dynamically stable by phonon and ab initio molecular dynamics simulations. Electronic structure investigations show that Sn2O3is a perspective material for gas sensing and catalyzing applications due to the unconnected bond on the top and bottom Sn atoms. The predicted tetragonal structure of SnO2is consistent with that in the literature. In the case of SnO, the thermodynamic phase diagram and phonon calculations showed that the two-dimensional orthorhombic structure is more stable than the tetragonal one. Ab initio molecular dynamic simulations at 300, 700, and 1100 K were performed to investigate the stability of all structures.

Crystal structure prediction of new ternary compounds is challenging due to a very large chemical space with many possible compositions, few of which turn out to be stable. Using the evolutionary algorithm USPEX, here we predicted potentially superhard ternary compounds in the W–Mo–B system. Five new stable ternary compounds with various chemical compositions were predicted at different temperatures, and the composition–temperature phase diagrams were calculated. Electronic properties of the new compounds were studied in detail to find their correlation with the mechanical properties, crystal structure, and atomic composition (i.e., mass percentage of elements within the molecular formula).