SEARCH · Engineering Papers
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
ZnN is Tetraauricupride structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Zn2+ is bonded in a body-centered cubic geometry to eight equivalent N2- atoms. All Zn–N bond lengths are 2.35 Å. N2- is bonded in a body-centered cubic geometry to eight equivalent Zn2+ atoms.
ZnN is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Zn2+ is bonded to six equivalent N2- atoms to form a mixture of corner and edge-sharing ZnN6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Zn–N bond lengths are 2.16 Å. N2- is bonded to six equivalent Zn2+ atoms to form a mixture of corner and edge-sharing NZn6 octahedra. The corner-sharing octahedral tilt angles are 0°.
ZnN is Zincblende, Sphalerite structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. Zn2+ is bonded to four equivalent N2- atoms to form corner-sharing ZnN4 tetrahedra. All Zn–N bond lengths are 1.99 Å. N2- is bonded to four equivalent Zn2+ atoms to form corner-sharing NZn4 tetrahedra.
Mn(ZnN)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are two inequivalent Mn2+ sites. In the first Mn2+ site, Mn2+ is bonded in a distorted trigonal planar geometry to three N3- atoms. There are a spread of Mn–N bond distances ranging from 1.87–1.97 Å. In the second Mn2+ site, Mn2+ is bonded in a distorted trigonal planar geometry to three N3- atoms. There is two shorter (1.87 Å) and one longer (1.96 Å) Mn–N bond length. There are four inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded in a trigonal non-coplanar geometry to three N3- atoms. There are two shorter (2.02 Å) and one longer (2.10 Å) Zn–N bond lengths. In the second Zn2+ site, Zn2+ is bonded in a trigonal non-coplanar geometry to three N3- atoms. There are two shorter (2.02 Å) and one longer (2.10 Å) Zn–N bond lengths. In the third Zn2+ site, Zn2+ is bonded to four N3- atoms to form a mixture of corner and edge-sharing ZnN4 trigonal pyramids. There are a spread of Zn–N bond distances ranging from 1.97–2.54 Å. In the fourth Zn2+ site, Zn2+ is bonded to four N3- atoms to form a mixture of corner and edge-sharing ZnN4 trigonal pyramids. There are a spread of Zn–N bond distances ranging from 1.97–2.55 Å. There are four inequivalent N3- sites. In the first N3- site, N3- is bonded in a 5-coordinate geometry to one Mn2+ and four Zn2+ atoms. In the second N3- site, N3- is bonded in a 5-coordinate geometry to one Mn2+ and four Zn2+ atoms. In the third N3- site, N3- is bonded to two Mn2+ and three Zn2+ atoms to form a mixture of corner and edge-sharing NMn2Zn3 trigonal bipyramids. In the fourth N3- site, N3- is bonded to two Mn2+ and three Zn2+ atoms to form a mixture of corner and edge-sharing NMn2Zn3 trigonal bipyramids.
Ti(ZnN)2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Ti2+ is bonded in a T-shaped geometry to three N3- atoms. There are a spread of Ti–N bond distances ranging from 1.90–2.07 Å. There are two inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded to five N3- atoms to form a mixture of corner and edge-sharing ZnN5 square pyramids. There are a spread of Zn–N bond distances ranging from 2.13–2.54 Å. In the second Zn2+ site, Zn2+ is bonded in a rectangular see-saw-like geometry to four N3- atoms. There are a spread of Zn–N bond distances ranging from 2.12–2.19 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded to one Ti2+ and five Zn2+ atoms to form a mixture of distorted corner and edge-sharing NTiZn5 octahedra. The corner-sharing octahedra tilt angles range from 6–13°. In the second N3- site, N3- is bonded to two equivalent Ti2+ and four Zn2+ atoms to form a mixture of distorted corner and edge-sharing NTi2Zn4 octahedra. The corner-sharing octahedra tilt angles range from 7–19°.
V(ZnN)2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. V2+ is bonded in a distorted T-shaped geometry to three N3- atoms. There are a spread of V–N bond distances ranging from 1.79–1.99 Å. There are two inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded to five N3- atoms to form distorted ZnN5 square pyramids that share corners with two equivalent ZnN5 square pyramids, corners with two equivalent ZnN4 trigonal pyramids, edges with three equivalent ZnN5 square pyramids, and edges with four equivalent ZnN4 trigonal pyramids. There are a spread of Zn–N bond distances ranging from 2.08–2.57 Å. In the second Zn2+ site, Zn2+ is bonded to four N3- atoms to form ZnN4 trigonal pyramids that share corners with two equivalent ZnN5 square pyramids, corners with two equivalent ZnN4 trigonal pyramids, edges with four equivalent ZnN5 square pyramids, and an edgeedge with one ZnN4 trigonal pyramid. There are a spread of Zn–N bond distances ranging from 2.12–2.31 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded to one V2+ and five Zn2+ atoms to form a mixture of distorted corner and edge-sharing NVZn5 octahedra. The corner-sharing octahedra tilt angles range from 13–18°. In the second N3- site, N3- is bonded to two equivalent V2+ and four Zn2+ atoms to form a mixture of distorted corner and edge-sharing NV2Zn4 octahedra. The corner-sharing octahedra tilt angles range from 15–21°.
Ca(ZnN)2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Ca2+ is bonded to six equivalent N3- atoms to form CaN6 octahedra that share corners with twelve equivalent ZnN4 tetrahedra, edges with six equivalent CaN6 octahedra, and edges with six equivalent ZnN4 tetrahedra. All Ca–N bond lengths are 2.55 Å. Zn2+ is bonded to four equivalent N3- atoms to form ZnN4 tetrahedra that share corners with six equivalent CaN6 octahedra, corners with six equivalent ZnN4 tetrahedra, edges with three equivalent CaN6 octahedra, and edges with three equivalent ZnN4 tetrahedra. The corner-sharing octahedra tilt angles range from 21–52°. There are three shorter (2.10 Å) and one longer (2.30 Å) Zn–N bond lengths. N3- is bonded in a 7-coordinate geometry to three equivalent Ca2+ and four equivalent Zn2+ atoms.
Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations
Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations
Explore the source record for details and available documents.
Antiperovskite nitrides with the general formula M 3 AN have attracted significant attention due to their tunable electronic and magnetic properties. Among them are many cobalt-based compounds predicted to exhibit high thermodynamic stability and intriguing magnetic behavior. Here, we report the synthesis and magnetic characterization of epitaxial Co3ZnN thin films grown by radio frequency sputtering on SrTiO 3 (STO) and MgO substrates. X-ray diffraction confirms phase-pure (00l)-oriented films with cube-on-cube epitaxy on STO, with a c-lattice parameter of 3.752 Å. Magnetic measurements reveal clear hysteresis at 2 K with a coercive field of ∼0.11 T and a small net moment of 0.108 μ B /f.u., suggesting either a canted antiferromagnetic (AFM) or ferrimagnetic (FiM) configuration. Temperature-dependent magnetization measurements show a transition near 25 K, with strong AFM interactions with Curie–Weiss temperature (Θ) = −80.13 K. Complementary density functional theory and Monte Carlo simulations indicate a ferromagnetic (FM) ground state, with the FM–AFM energy difference decreasing systematically with increasing supercell size, consistent with competition between FM and AFM/FiM interactions. These results highlight Co3ZnN as a magnetically complex antiperovskite nitride with competing exchange interactions.
Bis(2-pyridylthio)(p-tolylthio)methane, [Bptm STol ]H, has been synthesized by treatment of a 2:1 mixture of 2-mercaptopyridine and p-thiocresol with NaH, followed by addition of CHI3. Access to zinc complexes is provided by the reaction of [Bptm STol ]H with Zn[N(SiMe 3 ) 2 ] 2 to afford [Bptm STol ]ZnN(SiMe 3 ) 2 , from which the halide derivatives [Bptm STol ]ZnX (X = Cl, Br, I) are obtained via reaction with Me 3 SiX (X = Cl, Br, I), and the formate complex, [Bptm STol ]ZnO 2 CH, is obtained by treatment with CO 2 in the presence of PhSiH 3 . Here, the molecular structures of [Bptm STol ]ZnN(SiMe 3 ) 2 , [Bptm STol ]ZnX (X = Cl, Br, I) and [Bptm STol ]ZnO 2 CH have been determined by single crystal X-ray diffraction, which indicate that the four coordinate zinc centers adopt structures that are intermediate between idealized trigonal monopyramidal and seesaw geometries. [Bptm STol ]ZnO 2 CH is a catalyst for the hydrosilylation of CO 2 by (RO) 3 SiH at room temperature to afford the silyl formate, HCO 2 Si(OR) 3 .
MAX phase family has been extended by the addition of late transition metals at the A-site with the expectation of diverse functional properties. Here, we present our systematic density functional investigation on the thermodynamic and phonon stabilities, elastic properties, including elastic constants, elastic moduli and elastic anisotropy of newly synthesized Ti 2 ZnX (X = C, N) phases in comparison with conventional Ti 2 AlX (X = C, N). Due to the smaller size of N as compared to C, the unit cell dimension is reduced when C atoms are replaced by N atoms at the X-site. Furthermore, the Ti 2 ZnC and Ti 2 ZnN are stable at the equilibrium volume of 110.84 Å 3 and 105.70 Å 3 . The thermodynamic, mechanical and dynamical stabilities are validated by estimating the formation energies, elastic constants and phonon dispersions, respectively. The elastic properties of Ti 2 ZnN are less anisotropic as compared to those of Ti 2 ZnC. To understand the thin-film characteristics in Ti 2 ZnX, the surface properties with (001)-terminated slabs are investigated. Both Ti 2 ZnX bulk and (001)-surfaces exhibit metal-like electronic structures. There is a strong covalent bonding between Ti-X and Ti-Zn atoms confirmed by the charge density map and Mulliken population analysis. Additional states are generated at the Fermi level (EF) due to the unusual d-p states hybridization between Ti and Zn atoms. The anisotropy in chemical bonding is confirmed by the cleavage energy difference between Ti-X and Ti-Zn. Here, Ti(X)-001 and Zn-001 terminations are stable surfaces; however, in terms of chemical potentials, Zn-001 termination is the most favourable in Ti 2 ZnX.
Explore the source record for details and available documents.
Renewably driven, electrochemical conversion of carbon dioxide into value-added products is expected to be a critical tool in global decarbonization. However, theoretical studies based on the computational hydrogen electrode largely ignore the nonlinear effects of the applied potential on the calculated results, leading to inaccurate predictions of catalytic behavior or mechanistic pathways. Here, we use grand canonical density functional theory (GC-DFT) to model electrochemical CO2 reduction (CO2R) over metal- and nitrogen-doped graphene catalysts (MNCs) and explicitly include the effects of the applied potential. We used GC-DFT to compute the CO2 to CO reaction intermediate energies at -0.3, -0.7, and -1.2 VSHE catalyzed by MNCs each doped with 1 of the 10 3d block metals coordinated by four pyridinic nitrogen atoms. Our results predict that Sc-, Ti-, Co-, Cu-, and Zn-N4Cs effectively catalyze CO2R at moderate to large reducing potentials (-0.7 to -1.2 VSHE). ZnN4C is a particularly promising electrocatalyst for CO2R to CO both at low and moderate applied potentials based on our thermodynamic analysis. Our findings also explain the observed pH independence of CO production over FeN4C and predict that the rate-determining step of CO2R over FeN4C is not *CO2- formation but rather *CO desorption. Additionally, the GC-DFT-computed density of states analysis illustrates how the electronic states of MNCs and adsorbates change non-uniformly with applied potential, resulting in a significantly increased *CO2- stability relative to other intermediates and demonstrating that the formation of the adsorbed *CO2- anion is critical to CO2R activation. This work demonstrates how GC-DFT paves the way for physically realistic and accurate theoretical simulations of reacting electrochemical systems.
Here, the reactions of bis(2-pyridylthio)methane with Me 2 Zn and Zn[N(SiMe 3 ) 2 ] 2 afford [Bptm]ZnMe and [Bptm]ZnN(SiMe 3 ) 2 , thereby providing access to a variety of other [Bptm]ZnX derivatives, including the zinc hydride complex [Bptm]ZnH, which serves as a catalyst for the reduction of CO 2 and other carbonyl compounds via hydrosilylation and hydroboration.