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First-principles study of half-metallicity in semi-hydrogenated BC3, BC5, BC7, and B-doped graphone sheets.

Ding Y, Wang Y, Ni J, Shi L, Shi S, Li C, Tang W - Nanoscale Res Lett (2011)

Bottom Line: On the other hand, boron atoms weaken the magnetic moments of nearby carbon atoms and act as holes doped in the sheets.It induces the down shift of the Fermi level and the half-metallicity in semi-hydrogenated sheets.Our studies demonstrate that the semi-hydrogenation is an effective route to achieve half-metallicity in the boron-carbon systems.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics, Hangzhou Normal University, Hangzhou, Zhejiang 310036, People's Republic of China. dingyi2001@tsinghua.org.cn.

ABSTRACT
Using first principles calculations, we investigate the electronic structures of semi-hydrogenated BC3, BC5, BC7, and B-doped graphone sheets. We find that all the semi-hydrogenated boron-carbon sheets exhibit half-metallic behaviors. The magnetism originates from the non-bonding pz orbitals of carbon atoms, which cause the flat bands to satisfy the Stoner criterion. On the other hand, boron atoms weaken the magnetic moments of nearby carbon atoms and act as holes doped in the sheets. It induces the down shift of the Fermi level and the half-metallicity in semi-hydrogenated sheets. Our studies demonstrate that the semi-hydrogenation is an effective route to achieve half-metallicity in the boron-carbon systems.

No MeSH data available.


The structures and energy bands of semi-hydrogenated sheets. (a,c) the graphone and (b,d) the H-BC3 sheets. The calculated units are delineated by dotted lines in (a,b). The Fermi level is indicated as the line at E = 0 eV.
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Figure 1: The structures and energy bands of semi-hydrogenated sheets. (a,c) the graphone and (b,d) the H-BC3 sheets. The calculated units are delineated by dotted lines in (a,b). The Fermi level is indicated as the line at E = 0 eV.

Mentions: Figure 1 shows the structures of the graphone and H-BC3 sheets. In the graphone sheet, hydrogen atoms only bond with the carbon atoms at β sites (Cβ), not the carbon atoms at α sites (Cα). After semi-hydrogenation, the lattice constant of graphone is increased, which is 2.75% larger than that of graphene. The calculated C-C and C-H bond lengths are 1.50 and 1.16 Å, respectively, which agree well with the previous study [20]. Owing to the inequivalence of Cα and Cβ atoms, graphone is a semiconductor. As shown in Figure 1c, it has an indirect band gap of 0.48 eV, which is also in good accordance with the results by Zhou et al. [20]. In the H-BC3 sheet, only the Cβ atoms are bonding with hydrogen atoms, since under normal chemical potential, the hydrogen atoms prefer to bonding with carbon atoms in the BC3 sheet [26]. We have also calculated the conformation in which all the Cβ and Bβ atoms bond with hydrogen atoms. The binding energy of this conformation is - 1.40 eV/H, which is 0.13 eV/H less stable than the H-BC3 sheet shown in Figure 1b. The calculated B-C, C-C, and C-H bond lengths of the H-BC3 sheet are 1.53, 1.49, and 1.14 Å, respectively, and the lattice constant is 6.59% larger than that of graphene. Different from graphone, the C-H bonds tilt to the nearby boron atoms in the H-BC3 sheet. These tilting C-H bonds, together with the elongated lattice constant, decrease the repulsion between the hydrogen atoms and lead to a high binding energy of - 1.53 eV/H for the H-BC3 sheet.


First-principles study of half-metallicity in semi-hydrogenated BC3, BC5, BC7, and B-doped graphone sheets.

Ding Y, Wang Y, Ni J, Shi L, Shi S, Li C, Tang W - Nanoscale Res Lett (2011)

The structures and energy bands of semi-hydrogenated sheets. (a,c) the graphone and (b,d) the H-BC3 sheets. The calculated units are delineated by dotted lines in (a,b). The Fermi level is indicated as the line at E = 0 eV.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211247&req=5

Figure 1: The structures and energy bands of semi-hydrogenated sheets. (a,c) the graphone and (b,d) the H-BC3 sheets. The calculated units are delineated by dotted lines in (a,b). The Fermi level is indicated as the line at E = 0 eV.
Mentions: Figure 1 shows the structures of the graphone and H-BC3 sheets. In the graphone sheet, hydrogen atoms only bond with the carbon atoms at β sites (Cβ), not the carbon atoms at α sites (Cα). After semi-hydrogenation, the lattice constant of graphone is increased, which is 2.75% larger than that of graphene. The calculated C-C and C-H bond lengths are 1.50 and 1.16 Å, respectively, which agree well with the previous study [20]. Owing to the inequivalence of Cα and Cβ atoms, graphone is a semiconductor. As shown in Figure 1c, it has an indirect band gap of 0.48 eV, which is also in good accordance with the results by Zhou et al. [20]. In the H-BC3 sheet, only the Cβ atoms are bonding with hydrogen atoms, since under normal chemical potential, the hydrogen atoms prefer to bonding with carbon atoms in the BC3 sheet [26]. We have also calculated the conformation in which all the Cβ and Bβ atoms bond with hydrogen atoms. The binding energy of this conformation is - 1.40 eV/H, which is 0.13 eV/H less stable than the H-BC3 sheet shown in Figure 1b. The calculated B-C, C-C, and C-H bond lengths of the H-BC3 sheet are 1.53, 1.49, and 1.14 Å, respectively, and the lattice constant is 6.59% larger than that of graphene. Different from graphone, the C-H bonds tilt to the nearby boron atoms in the H-BC3 sheet. These tilting C-H bonds, together with the elongated lattice constant, decrease the repulsion between the hydrogen atoms and lead to a high binding energy of - 1.53 eV/H for the H-BC3 sheet.

Bottom Line: On the other hand, boron atoms weaken the magnetic moments of nearby carbon atoms and act as holes doped in the sheets.It induces the down shift of the Fermi level and the half-metallicity in semi-hydrogenated sheets.Our studies demonstrate that the semi-hydrogenation is an effective route to achieve half-metallicity in the boron-carbon systems.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics, Hangzhou Normal University, Hangzhou, Zhejiang 310036, People's Republic of China. dingyi2001@tsinghua.org.cn.

ABSTRACT
Using first principles calculations, we investigate the electronic structures of semi-hydrogenated BC3, BC5, BC7, and B-doped graphone sheets. We find that all the semi-hydrogenated boron-carbon sheets exhibit half-metallic behaviors. The magnetism originates from the non-bonding pz orbitals of carbon atoms, which cause the flat bands to satisfy the Stoner criterion. On the other hand, boron atoms weaken the magnetic moments of nearby carbon atoms and act as holes doped in the sheets. It induces the down shift of the Fermi level and the half-metallicity in semi-hydrogenated sheets. Our studies demonstrate that the semi-hydrogenation is an effective route to achieve half-metallicity in the boron-carbon systems.

No MeSH data available.