Prediction of stable high-pressure structures of tantalum nitride TaN2

Xing, Wandong; Wei, Zijie; Yu, Rong; Meng, Fanyan

doi:10.1016/j.jmst.2019.05.035

Cited by 10 publications

(14 citation statements)

References 60 publications

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“…Our labels (II and III) have been chosen to allow for a low-pressure monoclinic polymorph TaN 2 -I ( C 2/ m (12)), which occurs only in the phase diagram computed using the progressive extrapolation formula for the chemical potential change of nitrogen. Polymorphs I and III have been proposed previously for TaN 2 and NbN 2 . , All three TaN 2 structures are mixed nitride-per-nitrides, TaN 2 == Ta 2 N 2 (N 2 ). Two more phases with high nitrogen content emerge at high pressures.…”

Section: Resultsmentioning

confidence: 94%

“…Calculations using the generalized-gradient-approximation (GGA) in the form of the Perdew–Burke–Ernzerhof (PBE) functional yield similar but not identical results. Enthalpy differences vary by up to 5 meV per atom and have the impact that ε-TaN and Ta 5 N 6 do not appear in the convex hull, in contrast to previous calculations. , For comparison with experimental data, we stress that in all calculations we consider perfect ideal crystals only, while the nature of defects in a solid and its surface chemistry have an additional impact on the Gibbs energy. Additionally, the pathways and kinetics of decomposition or formation reactions or uneven reaction conditions may yield transient metastable intermediates or byproducts in an experiment. , …”

Section: Discussionmentioning

confidence: 92%

“…Monoclinic TaN 4 ( P 2 1 / c (14)) displays a finite chain of nitrogen atoms forming a complex N 8 10– -anion; hence, TaN 4 == Ta 2 (N 8 ). This structure has been proposed previously as well. , Finally, we include orthorhombic TaN 10 ( Immm (71)) that displays infinite chains of nitrogen together with enclosed N 2 molecules. This structure has been predicted for HfN 10 already …”

Section: Resultsmentioning

confidence: 98%

“…For structural explorations, we first computed the wealth of previously reported structures in the Ta–N system. − We then augmented the database by structures attained via an evolutionary algorithm (USPEX) as well as through a random structure search (AIRSS). Searches were performed at 40, 80, 120, and 160 GPa (and T = 0 K) with up to 20 and more atoms in a simulation cell.…”

Section: Computational Methodsmentioning

confidence: 99%

“…Tantalum–nitrogen compounds obtained in experiments include crystalline structures of Ta 2 N, TaN, Ta 5 N 6 , Ta 4 N 5 , Ta 2 N 3 , and Ta 3 N 5 . Much computational work has been devoted to identify additional Ta–N structures that can be obtained in high-pressure experiments. − Our early assessment of the pressure–temperature phase diagram of nitrogen-rich tantalum nitride addressed a phase boundary between TaN and Ta 3 N 5 at high temperature and high pressure . Motivated by this work, three experimental endeavors were reported.…”

Section: Introductionmentioning

confidence: 99%

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Computing the Tantalum–Nitrogen Phase Diagram at High Pressure and High Temperature

Alkhaldi

Kroll

2020

J. Phys. Chem. C

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We investigate the pressure−temperature phase diagram of the tantalum− nitrogen system through a combination of density functional theory computations and thermodynamic calculations. Accounting for the chemical potential of nitrogen at high pressure and high temperature, we obtain a Gibbs energy surface for every Ta−N phase in the pressure−temperature space. Combining the data yields a coherent stability map that identifies the one most favorable Ta−N structure at given p, T conditions in the presence of excess nitrogen. Slices through the phase diagram at constant pressure or constant temperature are used to examine the manifold of competing structures and locate optimum conditions with maximum driving force for successful syntheses. We rationalize high-pressure experiments that synthesized new Ta−N polymorphs and predict the temperature and pressure conditions necessary to synthesize Ta 2 N 2 (N 2 ) and Ta 2 N 8 .

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Section: Resultsmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 98%

Section: Computational Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Computing the Tantalum–Nitrogen Phase Diagram at High Pressure and High Temperature

Alkhaldi

Kroll

2020

J. Phys. Chem. C

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High‐Pressure Synthesis of Ultra‐Incompressible, Hard and Superconducting Tungsten Nitrides

Liang,

Osmond,

Krach

et al. 2024

Adv Funct Materials

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Transition metal nitrides, particularly those of 5d metals, are known for their outstanding properties, often relevant for industrial applications. Among these metal elements, tungsten is especially attractive given its low cost. In this high‐pressure investigation of the W–N system, two novel ultra‐incompressible tungsten nitride superconductors, namely W2N3 and W3N5, are successfully synthesized at 35 and 56 GPa, respectively, through a direct reaction between N2 and W in laser‐heated diamond anvil cells. Their crystal structure is determined using synchrotron single‐crystal X‐ray diffraction. While the W2N3 solid's sole constituting nitrogen species are N3‐ units, W3N5 features both discrete N3‐ as well as N24‐ pernitride anions. The bulk modulus of W2N3 and W3N5 is experimentally determined to be 380(3) and 406(7) GPa, and their ultra‐incompressible behavior is rationalized by their constituting WN7 polyhedra and their linkages. Importantly, both W2N3 and W3N5 are recoverable to ambient conditions and stable in air. Density functional theory calculations reveal W2N3 and W3N5 to have a Vickers hardness of 30 and 34 GPa, and superconducting transition temperatures at ambient pressure (50 GPa) of 11.6 K (9.8 K) and 9.4 K (7.2 K), respectively. Additionally, transport measurements performed at 50 GPa on W2N3 corroborate with the calculations.

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Thermal Expansion of Incompressible U₂S₃-Type Nb₂N₃ Synthesized in a Diamond Anvil Cell

et al. 2020

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A novel niobium nitride, U 2 S 3 -type Nb 2 N 3 , has been successfully synthesized by nitridation of δ-NbN above approximately 30 GPa in a laser-heated diamond anvil cell. Nb 2 N 3 crystallizes in the same orthorhombic structure (space group: Pnma) as η-Ta 2 N 3 . Nb 2 N 3 consists of regular-shaped polyhedra, and the bulk modulus has been determined to K 0 = 300(2) GPa. The low-temperature X-ray diffraction measurements have been successfully conducted for the tiny novel Nb 2 N 3 between 297.7(5) and 106.3(3) K under ambient pressure. Nb 2 N 3 shows no structural phase transition down to 106.3(3) K, and investigation of the linear thermal expansion coefficients yields α a = 3.36(9) × 10 −6 K −1 , α b = 5.39(10) × 10 −6 K −1 , α c = 6.77(15) × 10 −6 K −1 , respectively. Our study reveals that the incompressible novel nitride shows low thermal expansion behavior, which offers new insights for the development of functional nitrides and their crystal chemistry.U ltrahigh-pressure techniques allow one to synthesize novel transition-metal nitrides, pernitrides, and polynitrides, such as c-Zr 3 N 4 , 1 PtN 2 , 2 and FeN 4 . 3 These novel compounds are attracting attention from the viewpoints of superior mechanical and electronic properties and more. Among the early-transition-metal nitrides, in particular, niobium nitrides are considered to be extraordinary functional materials used as hard materials, 4 superconductors, 5,4 electrochemical capacitors, 6 and electrocatalysts. 7 Yet, most of the reported niobium nitrides, such as Nb

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Prediction of stable high-pressure structures of tantalum nitride TaN2

Cited by 10 publications

References 60 publications

Computing the Tantalum–Nitrogen Phase Diagram at High Pressure and High Temperature

Computing the Tantalum–Nitrogen Phase Diagram at High Pressure and High Temperature

High‐Pressure Synthesis of Ultra‐Incompressible, Hard and Superconducting Tungsten Nitrides

Thermal Expansion of Incompressible U₂S₃-Type Nb₂N₃ Synthesized in a Diamond Anvil Cell

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Prediction of stable high-pressure structures of tantalum nitride TaN2

Cited by 10 publications

References 60 publications

Computing the Tantalum–Nitrogen Phase Diagram at High Pressure and High Temperature

Computing the Tantalum–Nitrogen Phase Diagram at High Pressure and High Temperature

High‐Pressure Synthesis of Ultra‐Incompressible, Hard and Superconducting Tungsten Nitrides

Thermal Expansion of Incompressible U2S3-Type Nb2N3 Synthesized in a Diamond Anvil Cell

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Thermal Expansion of Incompressible U₂S₃-Type Nb₂N₃ Synthesized in a Diamond Anvil Cell