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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Structural changes induced by electric currents in a single crystal of Pr 2 CuO 4

We demonstrate an approach to the structural and electronic property modification of perovskites, focusing on Pr 2 CuO 4 , an undoped parent compound of a class of electron-doped copper-oxide superconductors. Currents were passed parallel or perpendicular to the copper oxygen layers with the voltage ramped up until a rapid drop in the resistivity was achieved, a process referred to as “flash.” The current was then further increased tenfold in current-control mode. This state was quenched by immersion into liquid nitrogen. Flash can drive many compounds into different atomic structures with new properties, whereas the quench freezes them into a long-lived state. Single-crystal neutron diffraction of as-grown and modified Pr 2 CuO 4 revealed a √10 ×√10 superlattice due to oxygen-vacancy order. The diffraction peak intensities of the superlattice of the modified sample were significantly enhanced relative to the pristine sample. Raman-active phonons in the modified sample were considerably sharper. Measurements of electrical resistivity, magnetization, and two-magnon Raman scattering indicate that the modification affected only the Pr-O layers, but not the Cu-O planes. These results point to enhanced oxygen-vacancy order in the modified samples well beyond what can be achieved without passing electrical current. Our work opens a new avenue toward electric field/quench control of structure and properties of layered perovskite oxides.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Observation of van der Waals phonons in the single-layer cuprate ( Bi , Pb ) 2 ( Sr , La ) 2 CuO 6 + δ

Interlayer van der Waals (vdW) coupling is generic in two-dimensional materials such as graphene and transition-metal dichalcogenides, which can induce very low-energy phonon modes. Using high-resolution inelastic hard x-ray scattering, we uncover the ultralow energy phonon mode along the Cu-O bond direction in the high- T c cuprate (Bi,Pb) 2 (Sr,La) 2 ⁢CuO 6+$\delta$ (Bi2201). The energy and full-width half-maximum (FWHM) of these modes are independent of temperature, while their intensity decreases with doping in accordance with an increasing c -axis lattice parameter. Here, we compare the experimental results to first-principles density functional theory simulations and identify the observed mode as a van der Waals phonon, which arises from the shear motion of the adjacent Bi-O layers. This shows that Bi-based cuprate has vibrational properties similar to graphene and transition-metal dichalcogenides, which can be exploited to engineer novel heterostructures.

36 MATERIALS SCIENCE↗
DOE OSTI2025

First-principles electron-phonon interactions and polarons in the parent cuprate La 2 CuO 4

Understanding electronic interactions in high-temperature superconductors is an outstanding challenge. In the widely studied cuprate materials, experimental evidence points to strong electron-phonon ( e -ph) coupling and broad photoemission spectra. Yet, the microscopic origin of this behavior is not fully understood. Here, we study e -ph interactions and polarons in a prototypical parent (undoped) cuprate, La 2 CuO 4 (LCO), by means of first-principles calculations. Leveraging parameter-free Hubbard-corrected density functional theory, we obtain a ground state with the band gap and Cu magnetic moment in nearly exact agreement with experiments. This enables a quantitative characterization of e -ph interactions. Our calculations reveal two classes of longitudinal optical (LO) phonons with strong e -ph coupling to hole states. These modes consist of bond stretching and bond bending in the Cu-O plane as well as vibrations of apical O atoms. The hole spectral functions, obtained with a cumulant method that can capture strong e -ph coupling, exhibit broad quasiparticle peaks with a small spectral weight ( Z ≈ 0.25 ) and pronounced LO-phonon sidebands characteristic of polaron effects. Our calculations predict features observed in photoemission spectra, including a 40-meV peak in the e -ph coupling distribution function not explained by existing models. These results show that the universal strong e -ph coupling found experimentally in doped lanthanum cuprates is also present in the parent compound, and elucidate its microscopic origin. Published by the American Physical Society 2025

Chang, Benjamin K. (ORCID:0000000313049324)↗
DOE OSTI2020

Materials Data on CuO by Materials Project

CuO is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Cu2+ is bonded to six equivalent O2- atoms to form a mixture of edge and corner-sharing CuO6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Cu–O bond lengths are 2.12 Å. O2- is bonded to six equivalent Cu2+ atoms to form a mixture of edge and corner-sharing OCu6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu4O3 by Materials Project

Cu4O3 crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. there are two inequivalent Cu+1.50+ sites. In the first Cu+1.50+ site, Cu+1.50+ is bonded in a square co-planar geometry to four O2- atoms. There is two shorter (1.92 Å) and two longer (2.01 Å) Cu–O bond length. In the second Cu+1.50+ site, Cu+1.50+ is bonded in a linear geometry to two equivalent O2- atoms. Both Cu–O bond lengths are 1.84 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Cu+1.50+ atoms to form a mixture of edge and corner-sharing OCu4 tetrahedra. In the second O2- site, O2- is bonded to four Cu+1.50+ atoms to form a mixture of edge and corner-sharing OCu4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuO by Materials Project

CuO crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Cu2+ is bonded in a square co-planar geometry to four equivalent O2- atoms. There is two shorter (1.94 Å) and two longer (1.96 Å) Cu–O bond length. O2- is bonded to four equivalent Cu2+ atoms to form a mixture of edge and corner-sharing OCu4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuO by Materials Project

CuO crystallizes in the tetragonal I4/mmm space group. The structure is zero-dimensional and consists of two CuO clusters. Cu2+ is bonded in a bent 150 degrees geometry to two equivalent O2- atoms. Both Cu–O bond lengths are 1.74 Å. O2- is bonded in a bent 120 degrees geometry to two equivalent Cu2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuO2 by Materials Project

CuO2 is trigonal omega-like structured and crystallizes in the trigonal R-3m space group. The structure is two-dimensional and consists of three CuO2 sheets oriented in the (0, 0, 1) direction. Cu is bonded to six equivalent O atoms to form edge-sharing CuO6 octahedra. All Cu–O bond lengths are 1.94 Å. O is bonded in a distorted trigonal non-coplanar geometry to three equivalent Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu8O by Materials Project

Cu8O crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are four inequivalent Cu sites. In the first Cu site, Cu is bonded in a 11-coordinate geometry to eleven Cu atoms. There are a spread of Cu–Cu bond distances ranging from 2.50–2.72 Å. In the second Cu site, Cu is bonded in a single-bond geometry to two equivalent Cu and one O atom. The Cu–O bond length is 1.93 Å. In the third Cu site, Cu is bonded in a single-bond geometry to four equivalent Cu and one O atom. The Cu–O bond length is 2.05 Å. In the fourth Cu site, Cu is bonded in a single-bond geometry to four equivalent Cu and one O atom. The Cu–O bond length is 2.06 Å. O is bonded in an octahedral geometry to six Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu8O7 by Materials Project

Cu8O7 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are four inequivalent Cu+1.75+ sites. In the first Cu+1.75+ site, Cu+1.75+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of Cu–O bond distances ranging from 1.92–2.00 Å. In the second Cu+1.75+ site, Cu+1.75+ is bonded in a T-shaped geometry to three O2- atoms. There are a spread of Cu–O bond distances ranging from 1.88–2.01 Å. In the third Cu+1.75+ site, Cu+1.75+ is bonded in a T-shaped geometry to three O2- atoms. There are a spread of Cu–O bond distances ranging from 1.89–2.01 Å. In the fourth Cu+1.75+ site, Cu+1.75+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of Cu–O bond distances ranging from 1.93–1.98 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to four Cu+1.75+ atoms to form a mixture of edge and corner-sharing OCu4 tetrahedra. In the second O2- site, O2- is bonded to four Cu+1.75+ atoms to form a mixture of edge and corner-sharing OCu4 tetrahedra. In the third O2- site, O2- is bonded to four Cu+1.75+ atoms to form a mixture of distorted edge and corner-sharing OCu4 tetrahedra. In the fourth O2- site, O2- is bonded to four Cu+1.75+ atoms to form a mixture of edge and corner-sharing OCu4 tetrahedra. In the fifth O2- site, O2- is bonded to four Cu+1.75+ atoms to form a mixture of edge and corner-sharing OCu4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu2O by Materials Project

Cu2O is Cuprite structured and crystallizes in the cubic Pn-3m space group. The structure is three-dimensional. Cu1+ is bonded in a linear geometry to two equivalent O2- atoms. Both Cu–O bond lengths are 1.86 Å. O2- is bonded to four equivalent Cu1+ atoms to form corner-sharing OCu4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuO2 by Materials Project

CuO2 is trigonal omega-like structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Cu is bonded to six equivalent O atoms to form edge-sharing CuO6 octahedra. All Cu–O bond lengths are 1.94 Å. O is bonded in a distorted T-shaped geometry to three equivalent Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuO by Materials Project

CuO crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Cu2+ sites. In the first Cu2+ site, Cu2+ is bonded in a linear geometry to two O2- atoms. Both Cu–O bond lengths are 1.82 Å. In the second Cu2+ site, Cu2+ is bonded in a 4-coordinate geometry to five O2- atoms. There are a spread of Cu–O bond distances ranging from 1.88–2.56 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Cu2+ atoms. In the second O2- site, O2- is bonded in a 4-coordinate geometry to four Cu2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuO2 by Materials Project

CuO2 crystallizes in the orthorhombic Fmmm space group. The structure is one-dimensional and consists of four CuO2 ribbons oriented in the (1, 0, 0) direction. Cu is bonded in a square co-planar geometry to four equivalent O atoms. All Cu–O bond lengths are 1.80 Å. O is bonded in a water-like geometry to two equivalent Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuO2 by Materials Project

CuO2 crystallizes in the orthorhombic Fmmm space group. The structure is one-dimensional and consists of four CuO2 ribbons oriented in the (1, 0, 0) direction. Cu is bonded in a square co-planar geometry to four equivalent O atoms. All Cu–O bond lengths are 1.81 Å. O is bonded in a water-like geometry to two equivalent Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuO by Materials Project

CuO crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Cu2+ is bonded in a square co-planar geometry to four equivalent O2- atoms. There is two shorter (1.95 Å) and two longer (1.96 Å) Cu–O bond length. O2- is bonded to four equivalent Cu2+ atoms to form a mixture of corner and edge-sharing OCu4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cu8O by Materials Project

Cu8O crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are four inequivalent Cu sites. In the first Cu site, Cu is bonded in a single-bond geometry to six Cu and one O atom. There are a spread of Cu–Cu bond distances ranging from 2.66–2.74 Å. The Cu–O bond length is 1.85 Å. In the second Cu site, Cu is bonded to twelve Cu atoms to form CuCu12 cuboctahedra that share corners with four equivalent CuCu12 cuboctahedra, corners with two equivalent OCu4 tetrahedra, edges with twelve CuCu12 cuboctahedra, edges with two equivalent OCu4 tetrahedra, and faces with eight CuCu12 cuboctahedra. There are a spread of Cu–Cu bond distances ranging from 2.52–2.79 Å. In the third Cu site, Cu is bonded to twelve Cu atoms to form CuCu12 cuboctahedra that share corners with twelve equivalent CuCu12 cuboctahedra, edges with twelve CuCu12 cuboctahedra, edges with three equivalent OCu4 tetrahedra, and faces with six CuCu12 cuboctahedra. There are a spread of Cu–Cu bond distances ranging from 2.52–2.84 Å. In the fourth Cu site, Cu is bonded in a single-bond geometry to six Cu and one O atom. The Cu–O bond length is 1.90 Å. O is bonded to four Cu atoms to form OCu4 tetrahedra that share corners with four equivalent CuCu12 cuboctahedra and edges with ten CuCu12 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuO2 by Materials Project

CuO2 is Cyanogen Chloride-derived structured and crystallizes in the orthorhombic Pmmm space group. The structure is one-dimensional and consists of one hydrogen peroxide molecule and one Cu ribbon oriented in the (1, 0, 0) direction. In the Cu ribbon, Cu is bonded in a distorted linear geometry to two equivalent Cu atoms. Both Cu–Cu bond lengths are 2.42 Å.

36 MATERIALS SCIENCE↗