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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Nd2CuO4 by Materials Project

Nd2CuO4 crystallizes in the orthorhombic Cmce space group. The structure is three-dimensional. Nd3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Nd–O bond distances ranging from 2.29–2.72 Å. Cu2+ is bonded to six O2- atoms to form corner-sharing CuO6 octahedra. The corner-sharing octahedral tilt angles are 13°. There are four shorter (1.93 Å) and two longer (2.43 Å) Cu–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 6-coordinate geometry to four equivalent Nd3+ and two equivalent Cu2+ atoms. In the second O2- site, O2- is bonded to four equivalent Nd3+ and one Cu2+ atom to form a mixture of distorted edge and corner-sharing ONd4Cu square pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nd2CuO4 by Materials Project

Nd2CuO4 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Nd3+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Nd–O bond distances ranging from 2.33–2.74 Å. Cu2+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Cu–O bond lengths are 1.99 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Nd3+ and two equivalent Cu2+ atoms to form distorted ONd4Cu2 octahedra that share corners with two equivalent ONd4Cu2 octahedra, corners with twelve equivalent ONd4 tetrahedra, edges with two equivalent ONd4Cu2 octahedra, edges with two equivalent ONd4 tetrahedra, and faces with four equivalent ONd4Cu2 octahedra. The corner-sharing octahedral tilt angles are 0°. In the second O2- site, O2- is bonded to four equivalent Nd3+ atoms to form ONd4 tetrahedra that share corners with twelve equivalent ONd4Cu2 octahedra, corners with four equivalent ONd4 tetrahedra, edges with two equivalent ONd4Cu2 octahedra, and edges with four equivalent ONd4 tetrahedra. The corner-sharing octahedra tilt angles range from 10–71°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nd2CuO4 by Materials Project

Nd2CuO4 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Nd3+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are four shorter (2.34 Å) and four longer (2.72 Å) Nd–O bond lengths. Cu2+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Cu–O bond lengths are 1.99 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Nd3+ and two equivalent Cu2+ atoms to form distorted ONd4Cu2 octahedra that share corners with two equivalent ONd4Cu2 octahedra, corners with twelve equivalent ONd4 tetrahedra, edges with two equivalent ONd4Cu2 octahedra, edges with two equivalent ONd4 tetrahedra, and faces with four equivalent ONd4Cu2 octahedra. The corner-sharing octahedral tilt angles are 0°. In the second O2- site, O2- is bonded to four equivalent Nd3+ atoms to form ONd4 tetrahedra that share corners with twelve equivalent ONd4Cu2 octahedra, corners with four equivalent ONd4 tetrahedra, edges with two equivalent ONd4Cu2 octahedra, and edges with four equivalent ONd4 tetrahedra. The corner-sharing octahedra tilt angles range from 11–69°.

36 MATERIALS SCIENCE↗
NASA NTRS1990

Preparation and characteristics of superconducting cuprate thin films: Nd(2-x)Ce(x)CuO4 and substituted Bi-system

Characteristics of the electron-doped-type Nd(2-x)Ce(x)CuO4 systems and substituted Bi2(Sr,Ln)3Cu2Oy system were systematically studied using the high quality thin-film samples. The Nd(2-x)Ce(x)CuO4 thin films with various Ce concentrations, x, were prepared by RF magnetron sputtering on SrTiO3 heated at around 500 C. After subsequent annealing at 1100 C in air, the films showed the c-axis orientation normal to the substrates. By means of the reducing treatment (annealing in a vacuum), superconductivity was induced for the films with 0.14 is less than or equal to x is less than or equal to 0.18. The superconductivity and transport properties of the films were strongly affected by the reducing treatment. The x = 0.15 film exhibited a sharp superconducting transition with zero resistivity at 22 K, in consistent with the diamagnetic properties. The resistivity of the films was fairly low with metallic characteristics, and the sight of the Hall coefficient was negative in the normal state. On the other hand, the normal-state optical measurements showed that the undoped Nd2CuO4 is a semiconductor with a charge transfer gap of 1.3 eV, and that, when Ce ions were doped, a plasma reflection due to the free-carriers came to be seen with the plasma frequency of 1.07 eV for 0.14 is less than or equal to x is less than or equal to 0.18. Moreover, x ray photoemission study revealed that the Cu valence of the film decreased for 2(+) for x = 0 to 1(+) for x = 0.15. These physical properties are in contrast with those of hole-doped-type cuprate superconductors. Bi2(Sr,Ln)3Cu2Oy thin films were also prepared on MgO substrates heated at 600 to 700 C by similar methods. It was found that the growth conditions for Bi-systems with two CuO2 planes were different for each composition and species of lanthanoid in the films. Moreover, preparation of Bi-system with three CuO2 planes was very difficult when lanthanoid atoms were doped in the system. Their electric transport properties and x ray photoemission spectroscopy were investigated. Carrier concentration and Cu valence were discussed with regard to the superconductivity.

Adachi, H.↗