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Journal of Physical Studies 23(3), Article 3703 [9 pages] (2019)
DOI: https://doi.org/10.30970/jps.23.3703 INTERCALATION OF Na ATOMS IN SnS2 FILMS: CALCULATIONS FROM THE FIRST PRINCIPLESR. M. Balabai, Yu. O. Prykhozha
Kryvyi Rih State Pedagogical University, |
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To reproduce the material of the electrodes for the accumulation of Na atoms in the form of 2-D monolayers SnS$_2$, consisting of two atomic layers of sulfur separated by an atomic layer of tin, the method of the construction of a super-lattice was used.
Using the methods of the functional of electronic density and pseudopotential, computational experiments on atomic models that reproduce the 2-D layered structure of tin chalcogenides with Na atoms intercalated in its interlayer space were performed from the first principles. The spatial distributions of the density of valence electrons and their intersections, the energy barriers of the migration of Na atoms in the interlayer space SnS$_2$, have been calculated, under different filling conditions during the movement of two metal atoms away from each other.
It has been established that the motion of Na atoms was accompanied by the collapse of energy barriers, whose magnitude depended on the degree of filling of the SnS$_2$ layer with metal atoms. Analyzing the energy barriers that arise in the path of a Na atom movement in the intermediate layer of the SnS$_2$, it was recorded that their values changed nonmonotonically with the degree of the filling of the layer. With an increase in the number of Na atoms, the total energy of the system increased from values 23.41 eV/atom to 111.77 eV/atom. It has been established that the migration energy reliefs of the Na atoms had one appearance with the filling of the SnS$_2$ layer from 12.5\0 25\%, and another with fullness of 37.5\% and more. The optimum filling of the SnS$_2$ layer with Na atoms in 75\% was observed, when the motion of Na atoms was accompanied by the lowest energy costs.
PACS number(s): 71.15.Mb, 73.61.At, 71.20.Be, 72.80.Ga, 73.50.Bk