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All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Novel Ultrafast Lu2O3:Yb Ceramics for Future HEP Applications

Inorganic scintillators activated by charge transfer luminescence Yb3+ are considered promising ultrafast material to break the ps timing barrier for future high energy physics applications. Inorganic scintillators in ceramic form are potentially more cost-effective than crystals because of their lower fabrication temperature and no need for aftergrowth mechanical processing. This paper reports an investigation on Lu2O3:Yb and Lu2xY2(1−x)O3:Yb scintillating ceramic samples fabricated by Radiation Monitoring Devices Inc. All samples show X-ray excited luminescence peaked at 370 nm. Ultrafast decay time of 1.1 ns was observed by using a microchannel plate-photomultiplier tube-based test bench at Caltech. Considering its intrinsic high density (9.4 g/cm3), Lu2O3:Yb ceramics are promising for future time of fight application for high energy physics experiments.

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

Materials Data on Lu2O3 by Materials Project

Lu2O3 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Lu3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Lu–O bond distances ranging from 2.14–2.52 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Lu3+ atoms to form OLu4 tetrahedra that share corners with six equivalent OLu6 octahedra, corners with six equivalent OLu4 tetrahedra, edges with three equivalent OLu6 octahedra, and edges with three equivalent OLu4 tetrahedra. The corner-sharing octahedra tilt angles range from 19–55°. In the second O2- site, O2- is bonded to six equivalent Lu3+ atoms to form OLu6 octahedra that share corners with twelve equivalent OLu4 tetrahedra, edges with six equivalent OLu6 octahedra, and edges with six equivalent OLu4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Lu2O3 by Materials Project

Lu2O3 is Corundum-like structured and crystallizes in the cubic Ia-3 space group. The structure is three-dimensional. there are two inequivalent Lu3+ sites. In the first Lu3+ site, Lu3+ is bonded to six equivalent O2- atoms to form a mixture of distorted edge and corner-sharing LuO6 octahedra. The corner-sharing octahedra tilt angles range from 54–56°. There are a spread of Lu–O bond distances ranging from 2.19–2.28 Å. In the second Lu3+ site, Lu3+ is bonded to six equivalent O2- atoms to form a mixture of edge and corner-sharing LuO6 octahedra. The corner-sharing octahedral tilt angles are 56°. All Lu–O bond lengths are 2.23 Å. O2- is bonded to four Lu3+ atoms to form a mixture of distorted edge and corner-sharing OLu4 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Lu2O3 by Materials Project

Lu2O3 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are three inequivalent Lu3+ sites. In the first Lu3+ site, Lu3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Lu–O bond distances ranging from 2.18–2.51 Å. In the second Lu3+ site, Lu3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Lu–O bond distances ranging from 2.19–2.68 Å. In the third Lu3+ site, Lu3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing LuO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Lu–O bond distances ranging from 2.14–2.40 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded to four Lu3+ atoms to form distorted OLu4 trigonal pyramids that share a cornercorner with one OLu6 octahedra, corners with nine OLu4 tetrahedra, corners with two equivalent OLu5 trigonal bipyramids, corners with two equivalent OLu4 trigonal pyramids, edges with three equivalent OLu5 trigonal bipyramids, and edges with two equivalent OLu4 trigonal pyramids. The corner-sharing octahedral tilt angles are 38°. In the second O2- site, O2- is bonded to five Lu3+ atoms to form distorted OLu5 trigonal bipyramids that share corners with seven OLu4 tetrahedra, corners with two equivalent OLu4 trigonal pyramids, edges with two equivalent OLu6 octahedra, edges with three OLu4 tetrahedra, edges with two equivalent OLu5 trigonal bipyramids, and edges with three equivalent OLu4 trigonal pyramids. In the third O2- site, O2- is bonded to four Lu3+ atoms to form OLu4 tetrahedra that share a cornercorner with one OLu6 octahedra, corners with four OLu4 tetrahedra, corners with five equivalent OLu5 trigonal bipyramids, corners with three equivalent OLu4 trigonal pyramids, edges with two equivalent OLu6 octahedra, edges with two equivalent OLu4 tetrahedra, and an edgeedge with one OLu5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 49°. In the fourth O2- site, O2- is bonded to four Lu3+ atoms to form distorted OLu4 tetrahedra that share corners with two equivalent OLu6 octahedra, corners with four OLu4 tetrahedra, corners with two equivalent OLu5 trigonal bipyramids, corners with six equivalent OLu4 trigonal pyramids, an edgeedge with one OLu6 octahedra, an edgeedge with one OLu4 tetrahedra, and edges with two equivalent OLu5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 12°. In the fifth O2- site, O2- is bonded to six Lu3+ atoms to form OLu6 octahedra that share corners with six OLu4 tetrahedra, corners with two equivalent OLu4 trigonal pyramids, edges with two equivalent OLu6 octahedra, edges with six OLu4 tetrahedra, and edges with four equivalent OLu5 trigonal bipyramids.

36 MATERIALS SCIENCE↗
NASA NTRS2021

Thermodynamics of the Lu2O3 – SiO2 system and comparison to other Rare Earth Silicates

Environmental barrier coatings are necessary to protect SiC based ceramics and composites from water vapor degradation in harsh engine environments. Currently, rare earth (RE) silicates are the most promising systems to protect SiC based ceramics and composites. This protection is largely based on reduced silica activity in these rare earth silicates which results in a lowered reactivity with water vapor. To that end, previous Knudsen effusion mass spectrometry (KEMS) studies have explored RE = Yb, Y silicates to measure the reduced silica activity and subsequent water vapor reactivity. Similarly, this work employs the KEMS technique to measure the SiO(g) vapor pressure in Lu containing RE silicates to calculate the activity of silica within the monosilicate [log(a(SiO2)) = -2351.1*1/T-1.6731] and the disilicate (log(a(SiO2)) = -4884.0*1/T + 2.2208) as a function of temperature. The enthalpies of formation for Lu monosilicate from the oxides and the elements were calculated to be -45±3 kJ/mol at 1550 K and -2831.1±12 kJ/mol at 298 K, respectively. The measured enthalpy of formation and those found in literature are compared to modeled values from density functional theory and those estimated using electronegativity.

Knudesen Effusion Mass Spectrometry↗
DOE OSTI2023

Effects of processing parameters on the morphologies of complex sesquioxide thin films

Controlling and predicting the morphology of lanthanide sesquioxides in thin film form is vital to their use in current applications. In the present study, single and codeposited Sm2O3, Er2O3, and Lu2O3 thin films were grown on yttria-stabilized zirconia (8%) substrates by radio frequency magnetron sputtering at room temperature and 500 °C. The effect of two different substrate temperatures and altering the oxide cation on the structural and morphological properties of the films was analyzed. The thin films were characterized by profilometry, scanning electron microscopy, transmission electron microscopy, and x-ray diffraction. The single-component Lu2O3 and Sm2O3 films obtained were of the cubic phase, and the Er2O3 was a mix of cubic and monoclinic phases. It was observed for both the Er2O3 and Lu2O3 films that increasing the substrate temperature to 500 °C resulted in larger grained polycrystalline films. In contrast, large grained polycrystalline films were obtained at both room temperature and 500 °C for Sm2O3 and uneven granularity increased as temperature increased. Codeposition of Lu2O3 and Sm2O3, and Lu2O3 and Er2O3 resulted in a cubic bixbyite phase (the C phase of the lanthanide sesquioxide) solid solution. It was observed that the structure and morphology of the films can be controlled by manipulating deposition parameters. Both substrate temperature and altering the oxide cation contributed to changes in crystallinity and grain structure, which can modify the chemical and physical properties of the films for their applications.

36 MATERIALS SCIENCE↗
NASA NTRS2009

Development of Ceramic Solid-State Laser Host Material

Polycrystalline ceramic laser materials are gaining importance in the development of novel diode-pumped solid-state lasers. Compared to single-crystals, ceramic laser materials offer advantages in terms of ease of fabrication, shape, size, and control of dopant concentrations. Recently, we have developed Neodymium doped Yttria (Nd:Y2O3) as a solid-state ceramic laser material. A scalable production method was utilized to make spherical non agglomerated and monodisperse metastable ceramic powders of compositions that were used to fabricate polycrystalline ceramic material components. This processing technique allowed for higher doping concentrations without the segregation problems that are normally encountered in single crystalline growth. We have successfully fabricated undoped and Neodymium doped Yttria material up to 2" in diameter, Ytterbium doped Yttria, and erbium doped Yttria. We are also in the process of developing other sesquioxides such as scandium Oxide (Sc2O3) and Lutesium Oxide (Lu2O3) doped with Ytterbium, erbium and thulium dopants. In this paper, we present our initial results on the material, optical, and spectroscopic properties of the doped and undoped sesquioxide materials. Polycrystalline ceramic lasers have enormous potential applications including remote sensing, chem.-bio detection, and space exploration research. It is also potentially much less expensive to produce ceramic laser materials compared to their single crystalline counterparts because of the shorter fabrication time and the potential for mass production in large sizes.

Prasad, Narasimha S.↗