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7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on K(AsIr)2 by Materials Project

K(IrAs)2 is Parent of FeAs superconductors-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. K is bonded in a body-centered cubic geometry to eight equivalent As atoms. All K–As bond lengths are 3.48 Å. Ir is bonded to four equivalent As atoms to form a mixture of distorted edge and corner-sharing IrAs4 tetrahedra. All Ir–As bond lengths are 2.47 Å. As is bonded in a 8-coordinate geometry to four equivalent K and four equivalent Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cs(AsIr)2 by Materials Project

Cs(IrAs)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Cs is bonded in a body-centered cubic geometry to eight equivalent As atoms. All Cs–As bond lengths are 3.71 Å. Ir is bonded to four equivalent As atoms to form a mixture of distorted edge and corner-sharing IrAs4 tetrahedra. All Ir–As bond lengths are 2.47 Å. As is bonded in a 8-coordinate geometry to four equivalent Cs and four equivalent Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AsIrS by Materials Project

IrAsS crystallizes in the cubic P2_13 space group. The structure is three-dimensional. Ir5+ is bonded to three equivalent As3- and three equivalent S2- atoms to form IrAs3S3 octahedra that share corners with twelve equivalent IrAs3S3 octahedra, corners with three equivalent AsIr3S tetrahedra, and corners with three equivalent SAsIr3 tetrahedra. The corner-sharing octahedral tilt angles are 64°. All Ir–As bond lengths are 2.46 Å. All Ir–S bond lengths are 2.43 Å. As3- is bonded to three equivalent Ir5+ and one S2- atom to form distorted AsIr3S tetrahedra that share corners with three equivalent IrAs3S3 octahedra, corners with six equivalent AsIr3S tetrahedra, and corners with nine equivalent SAsIr3 tetrahedra. The corner-sharing octahedral tilt angles are 78°. The As–S bond length is 2.34 Å. S2- is bonded to three equivalent Ir5+ and one As3- atom to form SAsIr3 tetrahedra that share corners with three equivalent IrAs3S3 octahedra, corners with six equivalent SAsIr3 tetrahedra, and corners with nine equivalent AsIr3S tetrahedra. The corner-sharing octahedral tilt angles are 78°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr2(AsIr)3 by Materials Project

Sr2(IrAs)3 crystallizes in the tetragonal P4/mmm space group. The structure is one-dimensional and consists of one Sr2(IrAs)3 ribbon oriented in the (0, 0, 1) direction. Sr is bonded in a linear geometry to one Ir and one As atom. The Sr–Ir bond length is 2.92 Å. The Sr–As bond length is 2.91 Å. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a linear geometry to one Sr and one As atom. The Ir–As bond length is 2.23 Å. In the second Ir site, Ir is bonded in a linear geometry to two equivalent As atoms. Both Ir–As bond lengths are 2.25 Å. There are two inequivalent As sites. In the first As site, As is bonded in a linear geometry to one Sr and one Ir atom. In the second As site, As is bonded in a linear geometry to two equivalent Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La(AsIr)2 by Materials Project

LaIr2As2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. La is bonded in a 4-coordinate geometry to eight Ir and eight As atoms. There are four shorter (3.32 Å) and four longer (3.37 Å) La–Ir bond lengths. There are four shorter (3.28 Å) and four longer (3.30 Å) La–As bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 12-coordinate geometry to four equivalent La and four equivalent As atoms. All Ir–As bond lengths are 2.58 Å. In the second Ir site, Ir is bonded in a 9-coordinate geometry to four equivalent La and five As atoms. There are one shorter (2.47 Å) and four longer (2.48 Å) Ir–As bond lengths. There are two inequivalent As sites. In the first As site, As is bonded in a 8-coordinate geometry to four equivalent La and four equivalent Ir atoms. In the second As site, As is bonded in a 9-coordinate geometry to four equivalent La and five Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb(AsIr)2 by Materials Project

Rb(IrAs)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Rb is bonded in a body-centered cubic geometry to eight equivalent As atoms. All Rb–As bond lengths are 3.57 Å. Ir is bonded to four equivalent As atoms to form a mixture of distorted edge and corner-sharing IrAs4 tetrahedra. All Ir–As bond lengths are 2.47 Å. As is bonded in a 8-coordinate geometry to four equivalent Rb and four equivalent Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Surface conduction and reduced electrical resistivity in ultrathin noncrystalline NbP semimetal

The electrical resistivity of conventional metals such as copper is known to increase in thin films as a result of electron-surface scattering, thus limiting the performance of metals in nanoscale electronics. Here, in this study, we find an unusual reduction of resistivity with decreasing film thickness in niobium phosphide (NbP) semimetal deposited at relatively low temperatures of 400°C. In films thinner than 5 nanometers, the room temperature resistivity (~34 microhm centimeters for 1.5-nanometer-thick NbP) is up to six times lower than the resistivity of our bulk NbP films, and lower than conventional metals at similar thickness (typically about 100 microhm centimeters). The NbP films are not crystalline but display local nanocrystalline, short-range order within an amorphous matrix. Our analysis suggests that the lower effective resistivity is caused by conduction through surface channels, together with high surface carrier density and sufficiently good mobility as the film thickness is reduced. These results and the fundamental insights obtained here could enable ultrathin, low-resistivity wires for nanoelectronics beyond the limitations of conventional metals.

42 ENGINEERING↗