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Nanomaterials
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Superhard Materials with Nanostructures
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Superhard Materials with Nanostructures

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Synthesis, Interfaces and Nanostructures".

Deadline for manuscript submissions: closed (30 November 2023) | Viewed by 8778

Special Issue Editors

Prof. Dr. Mikhail Popov

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Guest Editor
Technological Institute for Superhard and Novel Carbon Materials, Troitsk, Moscow, Russia
Interests: condensed matter physics (solid state physics); high pressure physics; mechanics of solids; material science; superhard ceramic and materials; Raman spectroscopy of carbon nanocluster-based/composite materials; technologies and applications of nanocarbon-based and nanocarbon scaled/modified materials
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Mingguang Yao

E-Mail Website
Guest Editor
State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
Interests: condensed matter physics (solid state physics); high pressure physics; mechanics of solids; superhard materials; Raman/IR spectroscopy of carbon materials; technologies and applications of carbon-based materials

Special Issue Information

Dear Colleagues,

The problem of creating materials that exceed the mechanical properties of diamond is widely discussed. The high values of strength and hardness of superhard materials formed by covalent bonds are due to the peculiarities of the mechanisms of plastic deformation at temperatures below the Debye temperature and are determined by their elastic modules. At the same time, in materials based on nanocluster structures, a decrease in the size of nanoclusters leads to an increase in elastic modules. This is due, on the one hand, to the surface effects in nanoclusters and the peculiarities of their structure. On the other hand, the increase in modules may be due to quantum size effects leading to an increase in the binding energy in nanoclusters.

Experimental and simulation data showed that quantum size effect was observed for diamond "quantum dots" (nano-diamond with dimensions of the order of 2-5 nm, quantum size restriction in three directions). As result, the diamond quantum dots bulk modulus corresponds to a value of about 600 GPa (bulk modulus of diamond is 443 GPa). Carbon nanocluster-based ultrahard fullerite has also higher than diamond bulk modulus (from 500 to 1000 GPa, depending on the structure and synthesis conditions) and hardness. Therefore, experimental studies and quantum mechanical modeling of elastic modules and force constants of covalent nanocluster structures are relevant for the creation of new superhard materials.

This Special Issue of Nanomaterials is not restricted by the fundamental problem of the increase in elastic modules with a decrease in the size of covalent nanoclusters. The main target is properties and applications of superhard materials with nanostructures. Generalization and systematization of existing and obtaining new experimental and theoretical results will lead to an understanding of the nature of their high mechanical strength and will allow significant progress in the field of their search and synthesis.

Prof. Dr. Mikhail Popov
Prof. Dr. Mingguang Yao
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Nanomaterials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • superhard materials
  • elasticity, plasticity
  • strength
  • hardness
  • covalent bonds
  • high pressure
  • nanocluster-based materials
  • structural self-organization
  • mechanical properties

Published Papers (5 papers)

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Research

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10 pages, 1573 KiB  
Article
Surface Tamm States of 2–5 nm Nanodiamond via Raman Spectroscopy
by Mikhail Popov, Fedor Khorobrykh, Sergei Klimin, Valentin Churkin, Danila Ovsyannikov and Alexander Kvashnin
Nanomaterials 2023, 13(4), 696; https://doi.org/10.3390/nano13040696 - 10 Feb 2023
Cited by 3 | Viewed by 1435
Abstract
We observed resonance effects in the Raman scattering of nanodiamonds with an average size of 2–5 nm excited at a wavelength of 1064 nm (1.16 eV). The resonant Raman spectrum of the 2–5 nm nanodiamonds consists of bands at wavelengths of 1325 and [...] Read more.
We observed resonance effects in the Raman scattering of nanodiamonds with an average size of 2–5 nm excited at a wavelength of 1064 nm (1.16 eV). The resonant Raman spectrum of the 2–5 nm nanodiamonds consists of bands at wavelengths of 1325 and 1600 cm−1, a band at 1100–1250 cm−1, and a plateau in the range from 1420 to 1630 cm−1. When excited away from the resonance (at a wavelength of 405 nm, 3.1 eV), the Raman spectrum consists of only three bands at 1325, 1500, and 1600 cm−1. It is important to note that the additional lines (1500 and 1600 cm−1) belong to the sp3-hybridized carbon bonds. The phonon density of states for the nanodiamonds (~1 nm) was calculated using moment tensor potentials (MTP), a class of machine-learning interatomic potentials. The presence of these modes in agreement with the lattice dynamics indicates the existence of bonds with force constants higher than in single-crystal diamonds. The observed resonant phenomena of the Raman scattering and the increase in the bulk modulus are explained by the presence of Tamm states with an energy of electronic transitions of approximately 1 eV, previously observed on the surface of single-crystal diamonds. Full article
(This article belongs to the Special Issue Superhard Materials with Nanostructures)
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11 pages, 6731 KiB  
Article
Synthesis of cBN-hBN-SiCw Nanocomposite with Superior Hardness, Strength, and Toughness
by Lei Sun, Yitong Zou, Mengdong Ma, Guangqian Li, Xiaoyu Wang, Xiang Zhang, Zewen Zhuge, Bing Liu, Yingju Wu, Baozhong Li and Zhisheng Zhao
Nanomaterials 2023, 13(1), 37; https://doi.org/10.3390/nano13010037 - 22 Dec 2022
Cited by 4 | Viewed by 1650
Abstract
Nanocomposites with one-dimensional (1D) and two-dimensional (2D) phases can demonstrate superior hardness, fracture toughness, and flexural strength. Cubic boron nitride-hexagonal boron nitride-silicon carbide whiskers (cBN-hBN-SiCw) nanocomposites with the simultaneous containing 1D SiCw and 2D hBN phases were successfully fabricated via [...] Read more.
Nanocomposites with one-dimensional (1D) and two-dimensional (2D) phases can demonstrate superior hardness, fracture toughness, and flexural strength. Cubic boron nitride-hexagonal boron nitride-silicon carbide whiskers (cBN-hBN-SiCw) nanocomposites with the simultaneous containing 1D SiCw and 2D hBN phases were successfully fabricated via the high-pressure sintering of a mixture of SiCw and cBN nanopowders. The hBN was generated in situ via the limited phase transition from cBN to hBN. Nanocomposites with 25 wt.% SiCw exhibited optimal comprehensive mechanical properties with Vickers hardness of 36.5 GPa, fracture toughness of 6.2 MPa·m1/2, and flexural strength of 687.4 MPa. Higher SiCw contents did not significantly affect the flexural strength but clearly decreased the hardness and toughness. The main toughening mechanism is believed to be a combination of hBN inter-layer sliding, SiCw pull-out, crack deflection, and crack bridging. Full article
(This article belongs to the Special Issue Superhard Materials with Nanostructures)
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9 pages, 1883 KiB  
Article
On the Tensile Strength of Spark Plasma Sintered AlMgB14 Ceramics
by Pavel Nikitin, Ilya Zhukov, Dmitrii Tkachev, Alexander Kozulin and Alexander Vorozhtsov
Nanomaterials 2022, 12(21), 3805; https://doi.org/10.3390/nano12213805 - 28 Oct 2022
Cited by 1 | Viewed by 1278
Abstract
In this work, the structure, phase composition, hardness and tensile strength of the AlMgB14-based material obtained by spark plasma sintering (SPS) were investigated. According to the XRD results, the spark plasma sintered material contains 94 wt% AlMgB14 phase and 6 [...] Read more.
In this work, the structure, phase composition, hardness and tensile strength of the AlMgB14-based material obtained by spark plasma sintering (SPS) were investigated. According to the XRD results, the spark plasma sintered material contains 94 wt% AlMgB14 phase and 6 wt% spinel MgAl2O4. Analysis of the SEM images showed that the obtained AlMgB14 sample has a dense structure; the relative density of the sample is 98.6%. The average microhardness of the spark plasma sintered (SPSed) sample is 29 ± 0.88 GPa. According to the results of the Brazilian test, the tensile strength of AlMgB14 is 56 MPa. The fracture is characterized by a single straight tensile crack that divides the sample along the compression line into two halves. The type of fracture in the AlMgB14 sample can be characterized as a cleavage fracture due to crack growth occurring in accordance with the transcrystalline fracture. The tensile strength of the obtained material is in good agreement with the tensile strength of boride and oxide ceramics studied in other works. Full article
(This article belongs to the Special Issue Superhard Materials with Nanostructures)
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10 pages, 3922 KiB  
Article
Effects of Diamond on Microstructure, Fracture Toughness, and Tribological Properties of TiO2-Diamond Composites
by Bing Liu, Zewen Zhuge, Song Zhao, Yitong Zou, Ke Tong, Lei Sun, Xiaoyu Wang, Zitai Liang, Baozhong Li, Tianye Jin, Junyun Chen and Zhisheng Zhao
Nanomaterials 2022, 12(21), 3733; https://doi.org/10.3390/nano12213733 - 24 Oct 2022
Cited by 1 | Viewed by 1661
Abstract
The reinforcements represented by graphene nanoplatelets, graphite, and carbon nanotubes have demonstrated the great potential of carbon materials as reinforcements to enhance the mechanical properties of TiO2. However, it is difficult to successfully prepare TiO2-diamond composites because diamond is [...] Read more.
The reinforcements represented by graphene nanoplatelets, graphite, and carbon nanotubes have demonstrated the great potential of carbon materials as reinforcements to enhance the mechanical properties of TiO2. However, it is difficult to successfully prepare TiO2-diamond composites because diamond is highly susceptible to oxidation or graphitization at relatively high sintering temperatures. In this work, the TiO2-diamond composites were successfully prepared using high-pressure sintering. The effect of diamond on the phase composition, microstructure, mechanical properties, and tribological properties was systemically investigated. Diamond can improve fracture toughness by the crack deflection mechanism. Furthermore, the addition of diamond can also significantly reduce the friction coefficient. The composite composed of 10 wt.% diamond exhibits optimum mechanical and tribological properties, with a hardness of 14.5 GPa, bending strength of 205.2 MPa, fracture toughness of 3.5 MPa∙m1/2, and a friction coefficient of 0.3. These results enlarge the family of titania-based composites and provide a feasible approach for the preparation of TiO2-diamond composites. Full article
(This article belongs to the Special Issue Superhard Materials with Nanostructures)
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Review

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19 pages, 3301 KiB  
Review
Mechanical Properties and Deformation Behavior of Superhard Lightweight Nanocrystalline Ceramics
by Byeongyun Jeong, Simanta Lahkar, Qi An and Kolan Madhav Reddy
Nanomaterials 2022, 12(18), 3228; https://doi.org/10.3390/nano12183228 - 16 Sep 2022
Cited by 5 | Viewed by 2076
Abstract
Lightweight polycrystalline ceramics possess promising physical, chemical, and mechanical properties, which can be used in a variety of important structural applications. However, these ceramics with coarse-grained structures are brittle and have low fracture toughness due to their rigid covalent bonding (more often consisting [...] Read more.
Lightweight polycrystalline ceramics possess promising physical, chemical, and mechanical properties, which can be used in a variety of important structural applications. However, these ceramics with coarse-grained structures are brittle and have low fracture toughness due to their rigid covalent bonding (more often consisting of high-angle grain boundaries) that can cause catastrophic failures. Nanocrystalline ceramics with soft interface phases or disordered structures at grain boundaries have been demonstrated to enhance their mechanical properties, such as strength, toughness, and ductility, significantly. In this review, the underlying deformation mechanisms that are contributing to the enhanced mechanical properties of superhard nanocrystalline ceramics, particularly in boron carbide and silicon carbide, are elucidated using state-of-the-art transmission electron microscopy and first-principles simulations. The observations on these superhard ceramics revealed that grain boundary sliding induced amorphization can effectively accommodate local deformation, leading to an outstanding combination of mechanical properties. Full article
(This article belongs to the Special Issue Superhard Materials with Nanostructures)
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