Hardness of cubic spinel Si3N4

He, Jingliang; Guo, Licong; Yu, Dongli; Liu, Riping; Tian, Yongjun; Wang, Hui-Tian

doi:10.1063/1.1832756

Cited by 56 publications

(32 citation statements)

References 31 publications

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“…[102,104,[118][119][120][121][122][123][124], and other high hardness materials [125][126][127]. Table 2 lists the calculated bandgap, density, Young's moduli, tensile strength, bulk modulus, shear modulus, and Vickers hardness of some 3D-linked SWCNTs composed of small CNTs.…”

Section: Theoretical Sectionmentioning

confidence: 99%

High-pressure behaviors of carbon nanotubes

Zhao

Zhou

et al. 2012

J. Superhard Mater.

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High-pressure behaviors of carbon nanotubesIn this paper, we have reviewed the experimental and theoretical studies on pressure-induced polygonization, ovalization, racetrack-shape deformation, and polymerization of carbon nanotubes (CNTs). The corresponding electronic, optical, and mechanical changes accompanying these behaviors have been discussed. The transformations of armchair (n, n) CNT bundles (n = 2, 3, 4, 6, and 8) Keywords: pressure-induced carbon nanotubes, polymerization, novel metastable carbons, electronic and mechanical characteristics. INTRODUCTIONCarbon adopts a wide range of allotropes with unique physical and chemical properties, e.g., graphite, diamond, fullerenes, nanotubes, chaoite, graphene, and amorphous carbon due to its ability to form sp-, sp 2 -, and sp 3 -hybridized bonds. Graphite, the most stable form of carbon at ambient pressure, has a layered and planar structure with the stacked graphene layers coupled by delocalized weak π bonds resulting in conductive and soft nature. Graphene, a recently rising star material, is one-atom-thick planar sheet with a honeycomb crystal lattice like that of graphite. Graphene has the amazing conductivity and strongest tensile strength along the planar layer directions but flexile in the other directions because of the conductive, strong, and flexile sp 2 bonds. Fullerenes and carbon nanotubes (CNTs) represent another two classes of fully sp 2 bonding carbons and are the focus of modern nanoscience and nanotechnology. Structurally, fullerenes are hollow graphitic cage structures composed of nonplanar 5-and 6-membered carbon rings. The smallest fullerene is C 20 [1] . Larger fullerene with increased diameter can also be formed [2,3]. Among them, purified C 60 and C 70 are now commercially available. CNTs can be considered as seamless cylinders formed by rolling single-or multilayer graphene. Different rolling manners yield distinct diametral and chiral CNTs. Given these unique configurations, CNTs possess a wide range of chemical and physical properties, e.g., low density, versatile electronic properties (insulating, semiconducting, Pressure is an effective means to induce the sp 2 -to-sp 3 bond change in carbon, and the produced metastable carbon phases strongly depend on the crystal structure and hybridization scheme of raw carbons, as well as on applied hydrostatic/nonhydrostatic pressure. For example, the compression of graphite can experimentally yield cubic and hexagonal diamonds, as well as a superhard coldcompressed post-graphite phase [5][6][7][8][9][10]. The glass carbon under pressure can transform into a superhard amorphous diamond [11], whereas the compression of C 60 and C 70 fullerenes can produce interesting 1D, 2D, and 3D C 60 and C 70 polymers, as well as other elusive new carbon phases [12][13][14][15][16][17][18][19][20][21][22][23][24][25]. Because a variety of CNT configurations can now be synthesized with a high yield, more interesting pressure-induced structural, electronic, and mechanical changes in CNTs are expected an...

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Section: Theoretical Sectionmentioning

confidence: 99%

High-pressure behaviors of carbon nanotubes

Zhao

Zhou

et al. 2012

J. Superhard Mater.

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“…However, this correlation is not always successful, as discussed in Refs. [5,13,14]. For instance, tungsten carbide (WC) has a very large bulk modulus (439 GPa) and shear modulus (282 GPa) but its hardness is only 30 GPa [15], clearly violating the Teter's linear correlation [see Fig.…”

Section: Introductionmentioning

confidence: 99%

Modeling hardness of polycrystalline materials and bulk metallic glasses

et al. 2011

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Though extensively studied, hardness, defined as the resistance of a material to deformation, still remains a challenging issue for a formal theoretical description due to its inherent mechanical complexity. The widely applied Teter's empirical correlation between hardness and shear modulus has been considered to be not always valid for a large variety of materials. Here, inspired by the classical work on Pugh's modulus ratio, we develop a theoretical model which establishes a robust correlation between hardness and elasticity for a wide class of materials, including bulk metallic glasses, with results in very good agreement with experiment. The simplified form of our model also provides an unambiguous theoretical evidence for Teter's empirical correlation.

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“…[1][2][3] Especially, 5d-TM dinitrides (PtN 2 , IrN 2 , and OsN 2 ) have been studied widely and synthesized under high pressure and temperature, showing very high bulk modulus and high shear modulus. [4][5][6][7][8][9] However, the drawback of these TMN 2 is their extreme high-pressure condition for synthesizing them.…”

Section: Introductionmentioning

confidence: 99%

Structure and mechanical properties of tantalum mononitride under high pressure: A first-principles study

Chang

Zhao

Zhou

et al. 2012

Journal of Applied Physics

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The structure and mechanical properties of tantalum mononitride (TaN) are investigated at high pressure from first-principles using the plane wave pseudopotential method within the local density approximation. Three stable phases were considered, i.e., two hexagonal phases (e and h) and a cubic d phase. The obtained equilibrium structure parameters and ground state mechanical properties are in excellent agreement with the experimental and other theoretical results. A full elastic tensor and crystal anisotropy of the ultra-incompressible TaN in three stable phases are determined in the wide pressure range. Results indicated that the elastic properties of TaN in three phases are strongly pressure dependent. And the hexagonal h-TaN is the most ultraincompressible among the consider phases, which suggests that the h phase of TaN is a potential candidate structure to be one of the ultraincompressible and hard materials. By the elastic stability criteria, it is predicted that h-TaN is not stable above 53.9 GPa. In addition, the calculated B/G ratio indicated that the e and d phases possess brittle nature in the range of pressure from 0 to 100 GPa. While h phase is brittleness at low pressure (below 8.2 GPa) and is strongly prone to ductility at high pressure (above 8.2 GPa). The calculated elastic anisotropic factors for three phases of TaN suggest that they are elastically highly anisotropic and strongly dependent on the propagation direction.

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Hardness of cubic spinel Si3N4

Cited by 56 publications

References 31 publications

High-pressure behaviors of carbon nanotubes

High-pressure behaviors of carbon nanotubes

Modeling hardness of polycrystalline materials and bulk metallic glasses

Structure and mechanical properties of tantalum mononitride under high pressure: A first-principles study

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