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9 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on LaGaO3 by Materials Project

LaGaO3 crystallizes in the trigonal R-3c space group. The structure is three-dimensional. La3+ is bonded in a 3-coordinate geometry to nine equivalent O2- atoms. There are three shorter (2.41 Å) and six longer (2.79 Å) La–O bond lengths. Ga3+ is bonded to six equivalent O2- atoms to form corner-sharing GaO6 octahedra. The corner-sharing octahedral tilt angles are 22°. All Ga–O bond lengths are 2.00 Å. O2- is bonded in a 5-coordinate geometry to three equivalent La3+ and two equivalent Ga3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LaGaO3 by Materials Project

LaGaO3 is Orthorhombic Perovskite-like structured and crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. La3+ is bonded in a 11-coordinate geometry to seven O2- atoms. There are a spread of La–O bond distances ranging from 2.39–2.82 Å. Ga3+ is bonded to six O2- atoms to form corner-sharing GaO6 octahedra. The corner-sharing octahedra tilt angles range from 20–26°. There are four shorter (2.00 Å) and two longer (2.02 Å) Ga–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent La3+ and two equivalent Ga3+ atoms. In the second O2- site, O2- is bonded in a 5-coordinate geometry to three equivalent La3+ and two equivalent Ga3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LaGaO3 by Materials Project

LaGaO3 is Orthorhombic Perovskite structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. La3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of La–O bond distances ranging from 2.41–2.80 Å. Ga3+ is bonded to six O2- atoms to form corner-sharing GaO6 octahedra. The corner-sharing octahedra tilt angles range from 24–25°. There are two shorter (2.01 Å) and four longer (2.02 Å) Ga–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to three equivalent La3+ and two equivalent Ga3+ atoms. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent La3+ and two equivalent Ga3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LaGaO3 by Materials Project

LaGaO3 is (Cubic) Perovskite structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional and consists of one gallium molecule and one LaO3 framework. In the LaO3 framework, La3+ is bonded to six equivalent O2- atoms to form corner-sharing LaO6 octahedra. The corner-sharing octahedral tilt angles are 0°. All La–O bond lengths are 2.30 Å. O2- is bonded in a linear geometry to two equivalent La3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LaGaO3 by Materials Project

LaGaO3 is Orthorhombic Perovskite-like structured and crystallizes in the trigonal R3c space group. The structure is three-dimensional. La3+ is bonded in a 3-coordinate geometry to nine equivalent O2- atoms. There are a spread of La–O bond distances ranging from 2.41–2.84 Å. Ga3+ is bonded to six equivalent O2- atoms to form corner-sharing GaO6 octahedra. The corner-sharing octahedral tilt angles are 22°. There are three shorter (2.00 Å) and three longer (2.01 Å) Ga–O bond lengths. O2- is bonded in a 5-coordinate geometry to three equivalent La3+ and two equivalent Ga3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Improved cell performance and sulphur tolerance using A-site substituted Sr2Fe1.4Ni0.1Mo0.5O6–δ anodes for solid-oxide fuel cells

Abstract Solid-oxide fuel cells (SOFCs) offer great promise for producing electricity using a wide variety of fuels such as natural gas, coal gas and gasified carbonaceous solids; however, conventional nickel-based anodes face great challenges due to contaminants in readily available fuels, especially sulphur-containing compounds. Thus, the development of new anode materials that can suppress sulphur poisoning is crucial to the realization of fuel-flexible and cost-effective SOFCs. In this work, La0.1Sr1.9Fe1.4Ni0.1Mo0.5O6–δ (LSFNM) and Pr0.1Sr1.9Fe1.4Ni0.1Mo0.5O6–δ (PSFNM) materials have been synthesized using a sol-gel method in air and investigated as anode materials for SOFCs. Metallic nanoparticle-decorated ceramic anodes were obtained by the reduction of LSFNM and PSFNM in H2 at 850°C, forming a Ruddlesden–Popper oxide with exsolved FeNi3 bimetallic nanoparticles. The electrochemical performance of the Sr2Fe1.4Ni0.1Mo0.5O6–δ ceramic anode was greatly enhanced by La doping of A-sites, resulting in a 44% decrease in the polarization resistance in reducing atmosphere. The maximum power densities of Sr- and Mg-doped LaGaO3 (LSGM) (300 μm) electrolyte-supported single cells with LSFNM as the anode reached 1.371 W cm −2 in H2 and 1.306 W cm–2 in 50 ppm H2S–H2 at 850°C. Meanwhile, PSFNM showed improved sulphur tolerance, which could be fully recovered after six cycles from H2 to 50 ppm H2S–H2 operation. This study indicates that LSFNM and PSFNM are promising high-performance anodes for SOFCs.

Li, Haixia↗
NASA NTRS1990

Millimeter wave surface resistance of RBa2Cu3O(7-delta) (R=Y,Eu,Dy,Sm,Er) superconductors

The measurements are reported of the millimeter wave surface resistance R(sub s) at 58.6 GHz of bulk samples of RBa2Cu3O(7-delta) (R = Y,Eu,Dy,Sm,Er) and of YBa2Cu3O(7-delta) superconducting films, in the temperature range from 20 to 300 K. The bulk samples were prepared by cold pressing the powders of RBa2Cu3O(7-delta) into one in. disks. The powders were prepared by several sinterings in one atmosphere of oxygen at 925 C, with grindings between sinterings, to obtain the superconducting phase. The thin films were deposited on SrTiO3 and LaGaO3 substrates by pulsed laser ablation. Each sample was measured by replacing the end wall of a gold-plated Te sub 013 circular mode copper cavity with the sample and determining the cavity quality factor . From the difference in the Q-factor of the cavity, with and without the sample, the R(sub s) of the sample was determined.

Miranda, F. A.↗
NASA NTRS1990

Millimeter-wave surface resistance of laser-ablated YBa2Cu3O(7-delta) superconducting films

The millimeter-wave surface resistance of YBa2Cu3O(7-delta) superconducting films was measured in a gold-plated copper host cavity at 58.6 GHz between 25 and 300 K. High-quality laser-ablated films of 1.2-micron thickness were deposited on SrTiO3 and LaGaO3 substrates. Their transition temperatures were 90.0 and 88.9 K, with a surface resistance at 70 K of 82 and 116 milliohms, respectively. These values are better than the values for the gold-plated cavity at the same temperature and frequency.

Miranda, F. A.↗
NASA NTRS1991

Microwave properties of YBa2Cu3O(7-delta) high-transition-temperature superconducting thin films measured by the power transmission method

The microwave response of YBa2Cu3O(7-delta) superconducting thin films deposited on LaAlO3, MgO, YSZ, and LaGaO3 substrates are studied. It is found that the microwave transmission properties are very weakly dependent on temperature in the normal state but change drastically upon transition to the superconducting state. In particular, the transmission decreases and there is a negative phase shift with respect to the phase at room temperature when the sample is cooled through its transition temperature. The magnetic penetration depth for all the films was determined from the surface reactance of the films. The microwave complex conductivity is determined in both the normal and the superconducting state. It is observed that both sigma1 and sigma2 increase in transition to the superconducting state. The surface resistivity is calculated for all the films.

Miranda, F. A.↗