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Hinge-like structure induced unusual properties of black phosphorus and new strategies to improve the thermoelectric performance.

Qin G, Yan QB, Qin Z, Yue SY, Cui HJ, Zheng QR, Su G - Sci Rep (2014)

Bottom Line: The hinge-like structure of BP brings unusual mechanical responses such as anisotropic Young's modulus and negative Poisson's ratio.By comparing the structure of BP with SnSe, a family of potential TE materials with hinge-like structure are suggested.This study not only exposes various novel properties of BP under strain, but also proposes effective strategies to seek for better TE materials.

View Article: PubMed Central - PubMed

Affiliation: College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China.

ABSTRACT
We systematically investigated the geometric, electronic and thermoelectric (TE) properties of bulk black phosphorus (BP) under strain. The hinge-like structure of BP brings unusual mechanical responses such as anisotropic Young's modulus and negative Poisson's ratio. A sensitive electronic structure of BP makes it transform among metal, direct and indirect semiconductors under strain. The maximal figure of merit ZT of BP is found to be 0.72 at 800 K that could be enhanced to 0.87 by exerting an appropriate strain, revealing BP could be a potential medium-high temperature TE material. Such strain-induced enhancements of TE performance are often observed to occur at the boundary of the direct-indirect band gap transition, which can be attributed to the increase of degeneracy of energy valleys at the transition point. By comparing the structure of BP with SnSe, a family of potential TE materials with hinge-like structure are suggested. This study not only exposes various novel properties of BP under strain, but also proposes effective strategies to seek for better TE materials.

No MeSH data available.


Related in: MedlinePlus

(a) A conventional cell and (b) a perspective side view of the crystal structure of black phosphorus.Within a hexagonal ring in one single layer, the upper three atoms are indicated as A, B and C, while the nether three atoms are indicated as D, E and F. The lattice parameters along x, y and z directions are defined as a, b and c, respectively.
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f1: (a) A conventional cell and (b) a perspective side view of the crystal structure of black phosphorus.Within a hexagonal ring in one single layer, the upper three atoms are indicated as A, B and C, while the nether three atoms are indicated as D, E and F. The lattice parameters along x, y and z directions are defined as a, b and c, respectively.

Mentions: BP has a layered orthorhombic structure with space group Cmca (No. 64), as shown in Fig. 1, which is very similar to the structure of SnSe except its lower symmetry with space group Pnma (No. 62). In BP, P atoms within a single layer are covalently bonded with each other, forming a puckered graphene-like hexagonal structure. The pucker is so dramatic that a hinge-like structure along the y direction is formed and the in-plane anisotropy is obvious, which is different from that of graphene. Besides, it is also reported that the individual layers in BP are stacked together by van der Waals Keesom forces26, unlike London forces in graphite27. The optimized geometric structures of BP in our calculations are in good agreement with experimental and previous computational results262829 (Supplemental Table S1).


Hinge-like structure induced unusual properties of black phosphorus and new strategies to improve the thermoelectric performance.

Qin G, Yan QB, Qin Z, Yue SY, Cui HJ, Zheng QR, Su G - Sci Rep (2014)

(a) A conventional cell and (b) a perspective side view of the crystal structure of black phosphorus.Within a hexagonal ring in one single layer, the upper three atoms are indicated as A, B and C, while the nether three atoms are indicated as D, E and F. The lattice parameters along x, y and z directions are defined as a, b and c, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4221793&req=5

f1: (a) A conventional cell and (b) a perspective side view of the crystal structure of black phosphorus.Within a hexagonal ring in one single layer, the upper three atoms are indicated as A, B and C, while the nether three atoms are indicated as D, E and F. The lattice parameters along x, y and z directions are defined as a, b and c, respectively.
Mentions: BP has a layered orthorhombic structure with space group Cmca (No. 64), as shown in Fig. 1, which is very similar to the structure of SnSe except its lower symmetry with space group Pnma (No. 62). In BP, P atoms within a single layer are covalently bonded with each other, forming a puckered graphene-like hexagonal structure. The pucker is so dramatic that a hinge-like structure along the y direction is formed and the in-plane anisotropy is obvious, which is different from that of graphene. Besides, it is also reported that the individual layers in BP are stacked together by van der Waals Keesom forces26, unlike London forces in graphite27. The optimized geometric structures of BP in our calculations are in good agreement with experimental and previous computational results262829 (Supplemental Table S1).

Bottom Line: The hinge-like structure of BP brings unusual mechanical responses such as anisotropic Young's modulus and negative Poisson's ratio.By comparing the structure of BP with SnSe, a family of potential TE materials with hinge-like structure are suggested.This study not only exposes various novel properties of BP under strain, but also proposes effective strategies to seek for better TE materials.

View Article: PubMed Central - PubMed

Affiliation: College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China.

ABSTRACT
We systematically investigated the geometric, electronic and thermoelectric (TE) properties of bulk black phosphorus (BP) under strain. The hinge-like structure of BP brings unusual mechanical responses such as anisotropic Young's modulus and negative Poisson's ratio. A sensitive electronic structure of BP makes it transform among metal, direct and indirect semiconductors under strain. The maximal figure of merit ZT of BP is found to be 0.72 at 800 K that could be enhanced to 0.87 by exerting an appropriate strain, revealing BP could be a potential medium-high temperature TE material. Such strain-induced enhancements of TE performance are often observed to occur at the boundary of the direct-indirect band gap transition, which can be attributed to the increase of degeneracy of energy valleys at the transition point. By comparing the structure of BP with SnSe, a family of potential TE materials with hinge-like structure are suggested. This study not only exposes various novel properties of BP under strain, but also proposes effective strategies to seek for better TE materials.

No MeSH data available.


Related in: MedlinePlus