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10 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Nd2O3 by Materials Project

Nd2O3 is Corundum-like structured and crystallizes in the cubic Ia-3 space group. The structure is three-dimensional. there are two inequivalent Nd3+ sites. In the first Nd3+ site, Nd3+ is bonded to six equivalent O2- atoms to form a mixture of distorted edge and corner-sharing NdO6 octahedra. The corner-sharing octahedra tilt angles range from 55–57°. There are a spread of Nd–O bond distances ranging from 2.37–2.47 Å. In the second Nd3+ site, Nd3+ is bonded to six equivalent O2- atoms to form a mixture of distorted edge and corner-sharing NdO6 octahedra. The corner-sharing octahedral tilt angles are 57°. All Nd–O bond lengths are 2.41 Å. O2- is bonded to four Nd3+ atoms to form a mixture of distorted edge and corner-sharing ONd4 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nd2O3 by Materials Project

Nd2O3 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Nd3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Nd–O bond distances ranging from 2.32–2.70 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Nd3+ atoms to form ONd4 tetrahedra that share corners with six equivalent ONd6 octahedra, corners with six equivalent ONd4 tetrahedra, edges with three equivalent ONd6 octahedra, and edges with three equivalent ONd4 tetrahedra. The corner-sharing octahedra tilt angles range from 18–56°. In the second O2- site, O2- is bonded to six equivalent Nd3+ atoms to form ONd6 octahedra that share corners with twelve equivalent ONd4 tetrahedra, edges with six equivalent ONd6 octahedra, and edges with six equivalent ONd4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nd2O3 by Materials Project

Nd2O3 is High-temperature superconductor-like structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional and consists of one neodimio molecule and one NdO3 framework. In the NdO3 framework, Nd3+ is bonded to six equivalent O2- atoms to form corner-sharing NdO6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Nd–O bond lengths are 2.25 Å. O2- is bonded in a linear geometry to two equivalent Nd3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nd2O3 by Materials Project

Nd2O3 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are three inequivalent Nd3+ sites. In the first Nd3+ site, Nd3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Nd–O bond distances ranging from 2.35–2.77 Å. In the second Nd3+ site, Nd3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Nd–O bond distances ranging from 2.35–2.83 Å. In the third Nd3+ site, Nd3+ is bonded to six O2- atoms to form a mixture of distorted edge and corner-sharing NdO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Nd–O bond distances ranging from 2.31–2.62 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to four Nd3+ atoms to form ONd4 tetrahedra that share corners with two equivalent ONd6 octahedra, corners with two equivalent ONd5 square pyramids, corners with four ONd4 tetrahedra, corners with six equivalent ONd4 trigonal pyramids, an edgeedge with one ONd6 octahedra, edges with two equivalent ONd5 square pyramids, and an edgeedge with one ONd4 tetrahedra. The corner-sharing octahedral tilt angles are 15°. In the second O2- site, O2- is bonded to four Nd3+ atoms to form distorted ONd4 trigonal pyramids that share a cornercorner with one ONd6 octahedra, corners with two equivalent ONd5 square pyramids, corners with nine ONd4 tetrahedra, corners with two equivalent ONd4 trigonal pyramids, edges with three equivalent ONd5 square pyramids, and edges with two equivalent ONd4 trigonal pyramids. The corner-sharing octahedral tilt angles are 35°. In the third O2- site, O2- is bonded to five Nd3+ atoms to form distorted ONd5 square pyramids that share corners with seven ONd4 tetrahedra, corners with two equivalent ONd4 trigonal pyramids, edges with two equivalent ONd6 octahedra, edges with two equivalent ONd5 square pyramids, edges with three ONd4 tetrahedra, and edges with three equivalent ONd4 trigonal pyramids. In the fourth O2- site, O2- is bonded to six Nd3+ atoms to form ONd6 octahedra that share corners with six ONd4 tetrahedra, corners with two equivalent ONd4 trigonal pyramids, edges with two equivalent ONd6 octahedra, edges with four equivalent ONd5 square pyramids, and edges with six ONd4 tetrahedra. In the fifth O2- site, O2- is bonded to four Nd3+ atoms to form ONd4 tetrahedra that share a cornercorner with one ONd6 octahedra, corners with five equivalent ONd5 square pyramids, corners with four ONd4 tetrahedra, corners with three equivalent ONd4 trigonal pyramids, edges with two equivalent ONd6 octahedra, an edgeedge with one ONd5 square pyramid, and edges with two equivalent ONd4 tetrahedra. The corner-sharing octahedral tilt angles are 51°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nd2O3 by Materials Project

Nd2O3 crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Nd3+ is bonded to six equivalent O2- atoms to form a mixture of distorted face, edge, and corner-sharing NdO6 pentagonal pyramids. All Nd–O bond lengths are 2.41 Å. O2- is bonded in a square co-planar geometry to four equivalent Nd3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Thermal conversion in air of rare-earth fluorides to rare-earth oxyfluorides and rare-earth oxides

Phase transformations of seven different rare-earth fluorides (i.e., REF3) where RE = La, Ce, Pr, Nd, Tm, Yb, Lu at temperatures ranging from 400–1400°C in air were investigated with X-ray diffraction. All of the REF3 compounds first transformed to oxyfluorides and then to oxides, with the exception of CeF3, which transformed directly to an oxide. This study focuses on the phase transitions of REF3 to REOx by simple heat-treatment processes in air and shows plausibility to remove RE elements from fluoride salt streams from molten salt reactors through fluoride-to-oxyfluoride or fluoride-to-oxide conversion mechanisms, which will result in precipitation. This could be used to remove fission product poisons from molten salt reactor waste streams. A waste form option for the resulting REOx products is lanthanide aluminoborosilicate (LABS) glass. To demonstrate this NdF3 was converted to Nd2O3 and immobilized in a LABS glass.

oxyfluoride, molten salt reactors, fluoride salt w↗
NASA NTRS1976

High modulus rare earth and beryllium containing silicate glass compositions

Glass compositions having a Young's modulus of at least 16 million psi and a specific modulus of at least 110 million inches consisting essentially of approximately, by weight, 20 to 43% SiO2, 8 to 21% Al2O3, 4 to 10% BeO, 27 to 58% of at least one oxide selected from a first group consisting of Y2O3, La2O3, Nd2O3, Ce2O3, Ce2O3, and the mixed rare earth oxides, and 3 to 12% of at least one oxide selected from a second group consisting of MgO, ZrO2, ZnO and CaO are described. The molar ratio of BeO to the total content of the first group oxides is from 1.0 to 3.0.

Bacon, J. F.↗
NASA NTRS1993

High efficiency direct thermal to electric energy conversion from radioisotope decay using selective emitters and spectrally tuned solar cells

Thermophotovoltaic (TPV) systems are attractive possibilities for direct thermal-to-electric energy conversion, but have typically required the use of black body radiators operating at high temperatures. Recent advances in both the understanding and performance of solid rare-earth oxide selective emitters make possible the use of TPV at temperatures as low as 1200K. Both selective emitter and filter system TPV systems are feasible. However, requirements on the filter system are severe in order to attain high efficiency. A thin-film of a rare-earth oxide is one method for producing an efficient, rugged selective emitter. An efficiency of 0.14 and power density of 9.2 W/KG at 1200K is calculated for a hypothetical thin-film neodymia (Nd2O3) selective emitter TPV system that uses radioisotope decay as the thermal energy source.

Chubb, Donald L.↗
NASA NTRS2002

Failure Morphologies of Cyclically Oxidized ZrO2-Based Thermal Barrier Coatings

Advanced and baseline thermal barrier coatings (TBCs) were thermal cycle tested in air at 1163 C until delamination or spallation of the ceramic top coat. The top coat of the advanced TBC s consisted of ZrO2 with various amounts of Y2O3, Yb2O3, Gd2O3, or Nd2O3 dopants. The composition of the top coat of the baseline TBC was ZrO2-8wt.%Y2O3. All top coats were deposited by air plasma spraying. A NiCrAlY or NiCoCrAlY bond coat was deposited by low pressure plasma spraying onto a single-crystal, Ni-base superalloy. The TBC lifetime for the baseline coatings was approximately 190 cycles (45 minutes at 1163 C per cycle) while the lifetime for the advanced coatings was as high as 425 cycles. The fracture surfaces and sample cross sections were examined after TBC failure by SEM and optical microscopy, and the top coats were further examined by X-ray diffraction. These post-test studies revealed that the fracture path largely followed splat boundaries with some trans-splat fracture. However, there were no obvious distinguishing features which explained the difference in TBC lifetimes between some of the advanced and baseline coatings.

Nesbitt, James A.↗
NASA NTRS1990

Failure Morphologies of Cyclically Oxidized ZrO2-Based Thermal Barrier Coatings

Plasma-sprayed thermal barrier coatings (TBC s) were thermal cycle tested in air at 1163 C until spallation of the top coat. Each thermal cycle consisted of a 45 minute exposure at the elevated temperature followed by a 15 minute cool to ambient temperature. The TBC s consisted of a ZrO2-based top coat containing various amounts of Y2O3, and/or Yb2O3, Gd2O3, and Nd2O3 applied by air plasma spraying and an MCrAlY bond coat applied by low pressure plasma spraying. The substrate was a single-crystal, Ni-based superalloy. The time to failure of the top coat varied from tens to hundreds of thermal cycles based on composition and spray parameters. The bond coat/top coat interface morphology and sample cross sections were examined by SEM and optical microscopy. The failure morphology following the cyclic oxidation testing will be discussed in relationship to the properties of the ceramic top coats.

Nesbit, James A.↗