Revealing unusual rigid diamond net analogues in superhard titanium carbides

Xu, Chao; Bao, Kuo; Li, Da; Duan, Defang; Yu, Hongyu; Jin, Xilian; Tian, Fubo; Liu, Bingbing; Cui, Tian

doi:10.1039/c8ra00400e

Cited by 12 publications

(10 citation statements)

References 67 publications

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“…TiC is predicted to take on the rocksalt F m3m structure, as indeed observed experimentally. The remaining stoichiometries Ti 6 C 5 , Ti 4 C 3 and Ti 3 C 2 have been reported in previous structure prediction studies [67]. Carbon dioxide, CO 2 , is the only predicted stable oxide of carbon, and is found in our searches in its experimentally observed, P a3-symmetry 'Phase I' structure [68].…”

Section: A the Ti-c-o Ternary Systemsupporting

confidence: 72%

Navigating the Ti-C-O and Al-C-O ternary systems through theory-driven discovery

Nelson,

Needs,

Pickard

2021

Preprint

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Computational searches for new materials are naturally turning from binary systems, to ternary and other multicomponent systems, and beyond. Here, we select the industrially-relevant metals titanium and aluminium and report the results of an extensive structure prediction study on the ternary titanium-carbon-oxygen (Ti-C-O) and aluminium-carbon-oxygen (Al-C-O) systems. We map out for the first time the full phase stability of Ti-C-O and Al-C-O compounds using firstprinciples calculations, through simple, efficient and highly parallel random structure searching in conjunction with techniques based on complex network theory. These phase stabilities emerge naturally from our 'data agnostic' approach, in which we map stable compounds without recourse to structural databases or other prior knowledge. A surprising find is the predicted ambient pressure stability of octet-rule-fulfiling titanium and aluminium carbonate: Ti(CO 3 ) 2 and Al 2 (CO 3 ) 3 , neither of which has to our knowledge been synthesised before. These materials could potentially act as carbon sequestering compounds. Our searches discover several additional stable and metastable ternary compounds supported by the Ti-C-O and Al-C-O systems.

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Section: A the Ti-c-o Ternary Systemsupporting

confidence: 72%

Navigating the Ti-C-O and Al-C-O ternary systems through theory-driven discovery

Nelson,

Needs,

Pickard

2021

Preprint

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“…Due to minuscule G (39 GPa) in NM zb-MnN, the hardness is negative. Moreover, in some TM light elements, Chen’s model may provide a hardness value that is quite different from the experiment one due to the lack of consideration of the metallicity and part of the covalent bond, especially in WN. − On the contrary, the results of Zhong’s model (Hv2) agree well with the experimental results. Thus, the two models were used in this work.…”

Section: Resultsmentioning

confidence: 65%

Bonding Properties of Manganese Nitrides at High Pressure and the Discovery of MnN₄with Planar N₄Rings

Bao

Zhao

et al. 2021

J. Phys. Chem. C

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It is not easy to synthesize high-quality manganese nitrides experimentally; however, owing to the intrinsic characteristics of manganese and nitrogen, these materials possess remarkable properties and have highly promising applications. In this study, we systematically examined the stoichiometric phase spaces of Mn−N compounds from 0 to 100 GPa using ab initio calculations and constructed a high-pressure magnetic phase diagram. Remarkably, N-rich MnN 4 with a planar N 4 ring was discovered for the first time in the pressure range of 40−100 GPa. The electronic structures revealed that the N 4 ring is formed of the sp 2 -hybridized nitrogen atoms. Furthermore, its superconducting transition temperature is approximately 1.6 K, and its bulk modulus is 381 GPa, thereby rendering it a potential hard superconductive material. Moreover, we determined a new phase transition sequence for MnN: the semi-conducting non-magnetic zb phase (5 GPa) first transforms to metallic antiferromagnetic NiAs (40 GPa), which further transforms to the more stable metallic ferromagnetic rs phase. The mechanical properties indicated that covalent interactions have a significant effect on the hardness of the N-rich structures and almost no effect on the Mn-rich structures in Mn−N compounds. Our work provides an overview of the Mn− N compounds and their properties under pressure and presents an updated phase diagram.

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“…Conductive diamond films and their nanostructures have been applied as the R-EC capacitor electrodes. They include boron-doped diamond (BDD), [25d] BDD networks (Figure 8C), [25d] carbon nanofiber (CNF)-coated BDD hybrid film (CNF/BDD) (Figure 8D), [25c] phosphorus-doped nanocrystalline diamond, [51a] graphite@nitrogen-doped diamond nano needle [85] graphene, [86] carbon nanofiber (CNF), [87] carbon nanotube (CNT), [86] diamond, [86] diamond-like carbon (DLC), [88] CNT/graphene, [89] CoTe 2 , [90] β-Co(OH) 2 , [91] FeCl 3 , [92] MnO 2 , [93] NiO, [94] TiC, [95] CuS, [96] polyaniline (PANI), [97] poly(3,4-ethylenedioxythiophene) (PEDOT), [98] and polypyrrole (PPy). [99] Image for graphene oxide: Reproduced with permission.…”

Section: Carbon Materialsmentioning

confidence: 99%

Electrochemical Capacitors with Confined Redox Electrolytes and Porous Electrodes

Yang

Zhang

et al. 2022

Advanced Materials

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Electrochemical capacitors (ECs), including electrical‐double‐layer capacitors and pseudocapacitors, feature high power densities but low energy densities. To improve the energy densities of ECs, redox electrolyte‐enhanced ECs (R‐ECs) or supercapbatteries are designed through employing confined soluble redox electrolytes and porous electrodes. In R‐ECs the energy storage is based on diffusion‐controlled faradaic processes of confined redox electrolytes at the surface of a porous electrode, which thus take the merits of high power densities of ECs and high energy densities of batteries. In the past few years, there has been great progress in the development of this energy storage technology, particularly in the design and synthesis of novel redox electrolytes and porous electrodes, as well as the configurations of new devices. Herein, a full‐screen picture of the fundamentals and the state‐of‐art progress of R‐ECs are given together with a discussion and outlines about the challenges and future perspectives of R‐ECs. The strategies to improve the performance of R‐ECs are highlighted from the aspects of their capacitances and capacitance retention, power densities, and energy densities. The insight into the philosophies behind these strategies will be favorable to promote the R‐EC technology toward practical applications of supercapacitors in different fields.

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Revealing unusual rigid diamond net analogues in superhard titanium carbides

Abstract: We found three diamond net analogues in titanium carbides firstly, including hard TiC2, superhard TiC3 and TiC4. Their hardness mainly originates from the strong covalent interactions of diamond-like C-layers.

Cited by 12 publications

References 67 publications

Navigating the Ti-C-O and Al-C-O ternary systems through theory-driven discovery

Navigating the Ti-C-O and Al-C-O ternary systems through theory-driven discovery

Bonding Properties of Manganese Nitrides at High Pressure and the Discovery of MnN₄with Planar N₄Rings

Electrochemical Capacitors with Confined Redox Electrolytes and Porous Electrodes

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Revealing unusual rigid diamond net analogues in superhard titanium carbides

Abstract: We found three diamond net analogues in titanium carbides firstly, including hard TiC2, superhard TiC3 and TiC4. Their hardness mainly originates from the strong covalent interactions of diamond-like C-layers.

Cited by 12 publications

References 67 publications

Navigating the Ti-C-O and Al-C-O ternary systems through theory-driven discovery

Navigating the Ti-C-O and Al-C-O ternary systems through theory-driven discovery

Bonding Properties of Manganese Nitrides at High Pressure and the Discovery of MnN4with Planar N4Rings

Electrochemical Capacitors with Confined Redox Electrolytes and Porous Electrodes

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Bonding Properties of Manganese Nitrides at High Pressure and the Discovery of MnN₄with Planar N₄Rings