scholarly journals Novel graphene-like two-dimensional bilayer germanene dioxide: electronic structure and optical properties

RSC Advances ◽  
2019 ◽  
Vol 9 (17) ◽  
pp. 9633-9639
Author(s):  
Yan-Mei Dou ◽  
Chang-Wen Zhang ◽  
Ping Li ◽  
Pei-Ji Wang

Using ab initio calculations, we present a two-dimensional (2D) α-2D-germanene dioxide material with an ideal sp3 bonding network which possesses a large band gap up to 2.50 eV.

2021 ◽  
Vol 63 (10) ◽  
pp. 1605
Author(s):  
Д.В. Суетин ◽  
А.В. Сердцев ◽  
Н.И. Медведева

The electronic structure and sodium diffusion in Na4-xKxMg(MoO4)3 with an alluadite structure have been investigated by ab initio methods. It was found that this molybdate is an insulator with a band gap of 3.5 eV for x = 0.25. The most probable positions of potassium in the sodium sublattice have been determined, and the preferred pathways for sodium migration have been established. It has been shown that the barriers to sodium diffusion in Na4-xKxMg(MoO4)3 significantly depend on the composition, position of potassium, and migration path. The introduction of potassium leads to a significant decrease in the barriers to both one-dimensional (1D) and two-dimensional (2D) sodium diffusion. However, the presence of potassium in 1D channels can hinder the rapid migration of sodium, and a sharp increase in conductivity occurs only at high temperatures due to the order-disorder transition.


2012 ◽  
Vol 63 ◽  
pp. 163-167 ◽  
Author(s):  
M.V. Lalić ◽  
Z.S. Popović ◽  
F.R. Vukajlović

2018 ◽  
Vol 32 (07) ◽  
pp. 1850092 ◽  
Author(s):  
Dandan Li ◽  
Juan Du ◽  
Qian Zhang ◽  
Congxin Xia ◽  
Shuyi Wei

Through first-principles calculations we study the electronic structures and optical properties of two-dimensional (2D) Sn[Formula: see text]Ti(Zr)[Formula: see text]S2 alloys. The results indicate that the band gap value of Sn[Formula: see text]Ti(Zr)[Formula: see text]S2 alloys is decreased continuously when Ti(Zr) concentration is increased, which is very beneficial to optoelectronic devices applications. Moreover, the static dielectric constant is increased when the Ti(Zr) concentration is increased in the 2D Sn[Formula: see text]Ti(Zr)[Formula: see text]S2 alloys. In addition, we also calculate the imaginary part [Formula: see text] dispersion of Sn[Formula: see text]Ti(Zr)[Formula: see text]S2 alloys along the plane with different Ti(Zr) concentrations. The threshold energy values decrease with increasing Ti(Zr) concentrations in the Sn[Formula: see text]Ti(Zr)[Formula: see text]S2 ternary alloys. Moreover, the calculations of formation energy also indicate that these 2D alloys can be fabricated under some experimental conditions. These results suggest that Ti(Zr) substituting Sn atom is an efficient way to tune the band gap and optical properties of 2D SnS2 nanosheets.


2019 ◽  
Vol 90 ◽  
pp. 77-86 ◽  
Author(s):  
Z. Souadia ◽  
A. Bouhemadou ◽  
S. Bin-Omran ◽  
R. Khenata ◽  
Y. Al-Douri ◽  
...  

2015 ◽  
Vol 29 (19) ◽  
pp. 1550100 ◽  
Author(s):  
Sui-Shuan Zhang ◽  
Zong-Yan Zhao ◽  
Pei-Zhi Yang

The crystal structure, electronic structure and optical properties of N-doped [Formula: see text] with different N impurity concentrations were calculated by density function theory within GGA[Formula: see text]+[Formula: see text]U method. The crystal distortion, impurity formation energy, band gap, band width and optical parameter of N-doped [Formula: see text] are closely related with N impurity concentration. Based on the calculated results, there are three new impurity energy levels emerging in the band gap of N-doped [Formula: see text], which determine the electronic structure and optical properties. The variations of optical properties induced by N doping are predominately determined by the unsaturated impurity states, which are more obvious at higher N impurity concentration. In addition, all the doping effects of N in both [Formula: see text]-quartz [Formula: see text] and [Formula: see text]-quartz [Formula: see text] are very similar. According to these findings, one could understand the relationship between nitrogen concentration and optical parameter of [Formula: see text] materials, and design new optoelectrionic Si–O–N compounds.


2011 ◽  
Vol 509 (17) ◽  
pp. 5230-5237 ◽  
Author(s):  
Altaf Hussain ◽  
Sitaram Aryal ◽  
Paul Rulis ◽  
M. Arshad Choudhry ◽  
Jun Chen ◽  
...  

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