Speaker
Description
N. Chetty1,2, N.F. Andriambelaza1
1 Department of Physics, University of Pretoria, Pretoria 0002, South Africa
2Faculty of Science, University of Witwatersrand, Johannesburg 2000, South Africa
Density functional theory (DFT) method as implemented in the Quantum Espresso packages was
used to investigate the effects of trivalent atoms such as B and Ga substituting Si atom in a bilayer
silica material. This bilayer system was recently proposed by researchers from Brookhaven lab
(Boscoboinik et al. [1]) as a suitable candidate for 2D representative of zeolites. The effects of the
trivalent atoms on the stability, structural and electronic properties of the 2D zeolite model were
explored. The formation energy analysis revealed that the introduction of B atom is exothermic
whereas that of Ga atom is endothermic. Next, the introduction of B and Ga were found to affect the
bond lengths of the system, however, it does not lead to a significant deformation of the structure.
Regarding the electronic properties, the Fermi level was shifted towards the valence band revealing
the obtention of p−type materials. The presence of B and Ga atoms in bilayer material results in a
net negative charge to the framework. In the present study, proton and alkali metals were considered
as charge balance. Their suitable site preference as well as the best candidate for charge balance
were identified. The density of states analysis showed that the presence of cations induces defect
states near the band edges narrowing the band gap. Our results provide detailed information about
the properties of the doped silica bilayer at the atomic level which is beneficial for its
nanotechnological applications as well as for its fully validation as 2D model for zeolite.
[1] Boscoboinik, J. Anibal, and Shamil Shaikhutdinov. Catalysis letters 144.12 (2014): 1987-1995.
