Microscopic theory of hardness and design of novel superhard crystals

Tian, Yongjun; Xu, Bin; Zhao, Zhisheng

doi:10.1016/j.ijrmhm.2012.02.021

Cited by 1,032 publications

(453 citation statements)

References 164 publications

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“…Microscopically, hardness can be defined as the combined resistance of chemical bonds in a crystal to indentation, with the determining factors of superhard materials being high bond strength, short bond distance, and high valence electron density (e.g., [654,655]). These factors can all be enhanced at HP, making HP a common route for synthesizing and studying superhard materials.…”

Section: Superhard Materialsmentioning

confidence: 99%

High-pressure studies with x-rays using diamond anvil cells

2016

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Pressure profoundly alters all states of matter. The symbiotic development of ultrahighpressure diamond anvil cells, to compress samples to sustainable multi-megabar pressures; and synchrotron x-ray techniques, to probe materials' properties in situ, has enabled the exploration of rich high-pressure (HP) science. In this article, we first introduce the essential concept of diamond anvil cell technology, together with recent developments and its integration with other extreme environments. We then provide an overview of the latest developments in HP synchrotron techniques, their applications, and current problems, followed by a discussion of HP scientific studies using x-rays in the key multidisciplinary fields. These HP studies include: HP x-ray emission spectroscopy, which provides information on the filled electronic states of HP samples; HP x-ray Raman spectroscopy, which probes the HP chemical bonding changes of light elements; HP electronic inelastic x-ray scattering spectroscopy, which accesses high energy electronic phenomena, including electronic band structure, Fermi surface, excitons, plasmons, and their dispersions; HP resonant inelastic x-ray scattering spectroscopy, which probes shallow core excitations, multiplet structures, and spin-resolved electronic structure; HP nuclear resonant x-ray spectroscopy, which provides phonon densities of state and time-resolved Mössbauer information; HP x-ray imaging, which provides information on hierarchical structures, dynamic processes, and internal strains; HP x-ray diffraction, which determines the fundamental structures and densities of single-crystal, polycrystalline, nanocrystalline, and non-crystalline materials; and HP radial x-ray diffraction, which yields deviatoric, elastic and rheological information. Integrating these tools with hydrostatic or uniaxial pressure media, laser and resistive heating, and cryogenic cooling, has enabled investigations of the structural, vibrational, electronic, and magnetic properties of materials over a wide range of pressure-temperature conditions.

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Section: Superhard Materialsmentioning

confidence: 99%

High-pressure studies with x-rays using diamond anvil cells

2016

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“…Therefore, designing and synthesizing novel hard and superhard materials are highly anticipated. These efforts concentrate in two areas, i.e., light element compounds in B-C-N-O system with short and strong three-dimensional (3D) covalent bonds and compounds fabricated by light elements (B, C, N, and O) and heavy transformation metals with high valence electron densities [1,2]. Currently, diamond is known to be the hardest material in the field of industry.…”

Section: Introductionmentioning

confidence: 99%

Covalent-bonded graphyne polymers with high hardness

Wang

et al. 2014

J. Superhard Mater.

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“…Both bulk and shear moduli are macroscopic concepts. Liu et al [30] employed this model to calculate the hardness in pyrite-type transition-metal pernitrides. In this study, we employ the model proposed by Gao et al [24] to calculate the theoretical Vickers hardness.…”

Section: Hardnessmentioning

confidence: 99%

Theoretical Study on Electronic, Optical Properties and Hardness of Technetium Phosphides under High Pressure

Feng

Cheng

et al. 2017

Crystals

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Abstract:In this paper, the structural properties of technetium phosphides Tc 3 P and TcP 4 are investigated by first principles at zero pressure and compared with the experimental values. In addition, the electronic properties of these two crystals in the pressure range of 0-40 GPa are investigated. Further, we discuss the change in the optical properties of technetium phosphides at high pressures. At the end of our study, we focus on the research of the hardness of TcP 4 at different pressures by employing a semiempirical method, and the effect of pressure on the hardness is studied. Results show that the hardness of TcP 4 increases with the increasing pressure, and the influence mechanism of pressure effect on the hardness of TcP 4 is also discussed.

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Microscopic theory of hardness and design of novel superhard crystals

Cited by 1,032 publications

References 164 publications

High-pressure studies with x-rays using diamond anvil cells

High-pressure studies with x-rays using diamond anvil cells

Covalent-bonded graphyne polymers with high hardness

Theoretical Study on Electronic, Optical Properties and Hardness of Technetium Phosphides under High Pressure

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