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At least 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Synthesis and Single Crystals of Refractory Oxides of Lanthanides and Thorium

At the completion of this program, we can report that we developed a considerable degree of technical improvements in our ability to perform hydrothermal reactions at high temperatures and pressures. We can now routinely perform reactions at 700-750°C and 200 MPa. Currently we are in the process of exploiting this new technology synthesizing a range of exotic new materials investigating relatively poorly understood materials. Our initial efforts focused on the chemistry of rare earth oxides with tetravalent and pentavalent oxides. We recently published a study of the lanthanides with Nb 5+ and Ta 5+ ions, where we grew oxides such as RENdO 4 and RETaO 4 as high quality single crystals. These compounds were targeted as potential hosts for luminescent and scintillation materials, particularly given that they are among the densest oxide hosts and hence have good potential as absorbers for high energy radiation like X-rays and gamma rays. We also isolated a range of unusual new rare earth tantalates with very complex structures. indicating that the chemistry is very sensitive to conditions. We performed some fairly comprehensive examinations of the solid-state chemistry of rare earth ions with various tetravalent metal ions especially Si 4+ , Ge 4+ , Sn 4+ and Ti 4+ . Given the potential role of rare earth silicates in immobilizing radioactive waste elements in long-term storage, and the similarity of our hydrothermal fluids with known geological conditions, this chemistry continues to be relevant. We prepared an extensive series of new lanthanide germanates (e.g. RE 13 Ge 6 O 31 (OH), BaRE 10 (GeO 4 ) 4 O 8 ). and found that there is there is almost no overlap between the chemistry of the rare earth silicates. Stannic oxide (SnO 2 ) is much more refractory and requires higher temperatures and of mineralizer concentrations. One significant result is the growth of RE 2 Sn 2 O 7 pyrochlore single crystals. These are of interest because the rare earth stannate pyrochlores are known to display a wide range of magnetic frustration such as spin ice behavior. We grew high quality single crystals of rare earth germanate and stannate pyrochlores and this led to a collaboration with Professor Kate Ross at Colorado State. Preliminary measurements, indicate that the crystals contain no detectable defects or site disorder. Initial neutron diffraction on single crystals was performed at Oak Ridge, and more detailed experiments involving the Ross group are underway at both NIST and ORNL. This particular chemistry has turned out to be the most potentially significant work on this project and the collaborative effort with Prof. Ross is the topic of a DoE renewal project on quantum materials. Our initial foray into the hydrothermal chemistry of rare earth titanates has also been very promising and a range of cubic and polar ferroic phases of the light rare earths RE 2 Ti 2 O 7 (RE = La - Pr) in the P2 1 phase. We also discovered an interesting new phase Ce 2 Ti 4 O 11 that can have implications in heavy metal immobilization and storage. along with a series of new rare earth titanates (La 5 Ti 4 O 15 (OH) Sm 3 TiO 5 (OH) 3 and Lu 5 Ti 2 O 11 (OH) with exceptionally complex structures. One interesting sidelight has been high temperature hydrothermal chemistry terbium, including the growth of large crystals of TbO(OH). This is not a new compound but it is the first time it has been grown as large single crystals. The Tb atom density is almost as high as that in Tb 2 O 3 and has a very high Verdet constant (ca. 70), making it a very attractive candidate as a Faraday rotator. Unfortunately it is not in a cubic structure but he material is hard, stable, pure and inexpensive, so should still be an attractive Faraday oscillator. We recently received a patent on this material. We also synthesized K 2 Tb(Ge 2 O 7 ) containing stable octahedral Tb 4+ ions, which appears to be the first example of a well-characterized Tb 4+ complex. Given that Tb 4+ has been proposed as a benign surrogate for more treacherous tetravalent ions such as Cf 4+ and Bk 4+ , we think that Tb 4+ silicates can be a particularly useful study for actinide immobilization and related work. We also began reaction studies with rare earths and both ReO 2 and RuO 2 . These resulted in large single crystals of species like RE 5 Ru 2 O 12 , RE 4 Re 2 O 11 , REReO 4 and RE 2 ReO 5 . Several of these samples have already been sent to ORNL for magnetic and neutron diffraction studies.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Exploring the Interaction of Amphiphilic Mycobacterial Lipoarabinomannan with Lipoproteins: Implications for Blood Based Diagnosis

Currently, over one-third of the global population is infected with tuberculosis (TB), one of the world’s most deadly infectious diseases. The current gold standard for TB diagnosis is microbiological culture, which can take up to 6-8 weeks, which is not conducive to timely treatment. There are no reliable diagnostics for TB. Disease manifestation and outcome of diagnostic tests for TB is influenced by co-morbidities such as HIV co-infection, further complicating diagnostics development. Thus, there is a need for reliable diagnostics for TB. This is especially true in pediatric populations where the differential disease presentation further complicates outcomes. This dissertation describes the development and evaluation of new tailored methods-lipoprotein capture and membrane insertion- for the discriminative detection of an amphiphilic mycobacterial biomarker, lipoarabinomannan (LAM), for diagnosis of TB in adult and pediatric populations. LAM is released by Mycobacterium tuberculosis during active infection and associates with serum lipoproteins such as high and low density lipoproteins (HDL/LDL) in the human host. The guiding hypothesis of this work is that the vi sequestration of LAM in immune complexes and by lipoprotein carriers in the host contributes to difficulty in detection of the amphiphilic antigen in blood. To this end, we have evaluated the use of tailored amphiphile detection assays to process and measure sequestered LAM in host blood, and examined the application of this methodology in adults and children with TB disease. In addition, we have developed and studied an in vitro cell model to further extrapolate the impact of association of LAM with host carriers on its ability to induce innate immune processes, in order to better refine and design strategies for its direct detection. Overall, our conclusions indicate that the amphiphilic biochemistry of LAM and its interaction with lipoproteins is a feature which should be taken into account for the effective development of diagnostics.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS2011

Surface and Atmospheric Contributions to Passive Microwave Brightness Temperatures for Falling Snow Events

Physically based passive microwave precipitation retrieval algorithms require a set of relationships between satellite -observed brightness temperatures (TBs) and the physical state of the underlying atmosphere and surface. These relationships are nonlinear, such that inversions are ill ]posed especially over variable land surfaces. In order to elucidate these relationships, this work presents a theoretical analysis using TB weighting functions to quantify the percentage influence of the TB resulting from absorption, emission, and/or reflection from the surface, as well as from frozen hydrometeors in clouds, from atmospheric water vapor, and from other contributors. The percentage analysis was also compared to Jacobians. The results are presented for frequencies from 10 to 874 GHz, for individual snow profiles, and for averages over three cloud-resolving model simulations of falling snow. The bulk structure (e.g., ice water path and cloud depth) of the underlying cloud scene was found to affect the resultant TB and percentages, producing different values for blizzard, lake effect, and synoptic snow events. The slant path at a 53 viewing angle increases the hydrometeor contributions relative to nadir viewing channels. Jacobians provide the magnitude and direction of change in the TB values due to a change in the underlying scene; however, the percentage analysis provides detailed information on how that change affected contributions to the TB from the surface, hydrometeors, and water vapor. The TB percentage information presented in this paper provides information about the relative contributions to the TB and supplies key pieces of information required to develop and improve precipitation retrievals over land surfaces.

Skofronick-Jackson, Gail↗
DOE OSTI2020

Materials Data on TbAgGe by Materials Project

TbAgGe crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Tb is bonded in a 11-coordinate geometry to five Ag and six equivalent Ge atoms. There are one shorter (2.93 Å) and four longer (3.07 Å) Tb–Ag bond lengths. There are two shorter (3.23 Å) and four longer (3.31 Å) Tb–Ge bond lengths. There are two inequivalent Ag sites. In the first Ag site, Ag is bonded in a 9-coordinate geometry to six equivalent Tb and three equivalent Ge atoms. All Ag–Ge bond lengths are 2.74 Å. In the second Ag site, Ag is bonded in a 9-coordinate geometry to three equivalent Tb and six equivalent Ge atoms. All Ag–Ge bond lengths are 2.86 Å. Ge is bonded in a distorted q6 geometry to six equivalent Tb and four Ag atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tb3Al by Materials Project

Tb3Al is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Tb is bonded to eight equivalent Tb and four equivalent Al atoms to form distorted TbTb8Al4 cuboctahedra that share corners with twelve equivalent TbTb8Al4 cuboctahedra, edges with eight equivalent AlTb12 cuboctahedra, edges with sixteen equivalent TbTb8Al4 cuboctahedra, faces with four equivalent AlTb12 cuboctahedra, and faces with fourteen equivalent TbTb8Al4 cuboctahedra. All Tb–Tb bond lengths are 3.38 Å. All Tb–Al bond lengths are 3.38 Å. Al is bonded to twelve equivalent Tb atoms to form AlTb12 cuboctahedra that share corners with twelve equivalent AlTb12 cuboctahedra, edges with twenty-four equivalent TbTb8Al4 cuboctahedra, faces with six equivalent AlTb12 cuboctahedra, and faces with twelve equivalent TbTb8Al4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TbAlNi by Materials Project

TbNiAl crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Tb is bonded in a 11-coordinate geometry to five Ni and six equivalent Al atoms. There are four shorter (2.86 Å) and one longer (2.95 Å) Tb–Ni bond lengths. There are two shorter (3.11 Å) and four longer (3.20 Å) Tb–Al bond lengths. There are two inequivalent Ni sites. In the first Ni site, Ni is bonded in a 9-coordinate geometry to three equivalent Tb and six equivalent Al atoms. All Ni–Al bond lengths are 2.54 Å. In the second Ni site, Ni is bonded in a 9-coordinate geometry to six equivalent Tb and three equivalent Al atoms. All Ni–Al bond lengths are 2.77 Å. Al is bonded in a 12-coordinate geometry to six equivalent Tb, four Ni, and two equivalent Al atoms. Both Al–Al bond lengths are 2.88 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TbZnSn2 by Materials Project

TbZnSn2 is Parent of FeAs superconductors-derived structured and crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Tb is bonded to four equivalent Zn and eight Sn atoms to form a mixture of face, edge, and corner-sharing TbZn4Sn8 cuboctahedra. All Tb–Zn bond lengths are 3.28 Å. There are four shorter (3.16 Å) and four longer (3.32 Å) Tb–Sn bond lengths. Zn is bonded in a 12-coordinate geometry to four equivalent Tb and four equivalent Sn atoms. All Zn–Sn bond lengths are 2.85 Å. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 8-coordinate geometry to four equivalent Tb and four equivalent Zn atoms. In the second Sn site, Sn is bonded in a 8-coordinate geometry to four equivalent Tb and four equivalent Sn atoms. All Sn–Sn bond lengths are 3.10 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TbZnNi by Materials Project

TbNiZn crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Tb is bonded in a 11-coordinate geometry to five Ni and six equivalent Zn atoms. There are four shorter (2.85 Å) and one longer (2.88 Å) Tb–Ni bond lengths. There are two shorter (3.10 Å) and four longer (3.14 Å) Tb–Zn bond lengths. There are two inequivalent Ni sites. In the first Ni site, Ni is bonded in a 9-coordinate geometry to three equivalent Tb and six equivalent Zn atoms. All Ni–Zn bond lengths are 2.54 Å. In the second Ni site, Ni is bonded in a 9-coordinate geometry to six equivalent Tb and three equivalent Zn atoms. All Ni–Zn bond lengths are 2.72 Å. Zn is bonded in a 12-coordinate geometry to six equivalent Tb, four Ni, and two equivalent Zn atoms. Both Zn–Zn bond lengths are 2.95 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TbGa3Os by Materials Project

TbOsGa3 crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Tb is bonded in a 8-coordinate geometry to four equivalent Os and ten Ga atoms. All Tb–Os bond lengths are 3.22 Å. There are eight shorter (2.97 Å) and two longer (3.22 Å) Tb–Ga bond lengths. Os is bonded to four equivalent Tb and eight equivalent Ga atoms to form distorted OsTb4Ga8 cuboctahedra that share corners with four equivalent OsTb4Ga8 cuboctahedra, edges with four equivalent GaTb6 octahedra, and faces with eight equivalent OsTb4Ga8 cuboctahedra. All Os–Ga bond lengths are 2.68 Å. There are two inequivalent Ga sites. In the first Ga site, Ga is bonded to six equivalent Tb atoms to form GaTb6 octahedra that share corners with six equivalent GaTb6 octahedra and edges with twelve equivalent OsTb4Ga8 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. In the second Ga site, Ga is bonded in a 6-coordinate geometry to three equivalent Tb, three equivalent Os, and three equivalent Ga atoms. All Ga–Ga bond lengths are 2.71 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TbInCu by Materials Project

TbCuIn crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Tb is bonded in a 11-coordinate geometry to five Cu and six equivalent In atoms. There are four shorter (3.01 Å) and one longer (3.06 Å) Tb–Cu bond lengths. There are two shorter (3.20 Å) and four longer (3.34 Å) Tb–In bond lengths. There are two inequivalent Cu sites. In the first Cu site, Cu is bonded in a 9-coordinate geometry to six equivalent Tb and three equivalent In atoms. All Cu–In bond lengths are 2.83 Å. In the second Cu site, Cu is bonded in a 9-coordinate geometry to three equivalent Tb and six equivalent In atoms. All Cu–In bond lengths are 2.74 Å. In is bonded in a 10-coordinate geometry to six equivalent Tb and four Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TbMn2 by Materials Project

TbMn2 is Cubic Laves structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Tb is bonded in a 12-coordinate geometry to four equivalent Tb and twelve equivalent Mn atoms. All Tb–Tb bond lengths are 3.14 Å. All Tb–Mn bond lengths are 3.01 Å. Mn is bonded to six equivalent Tb and six equivalent Mn atoms to form a mixture of corner, edge, and face-sharing MnTb6Mn6 cuboctahedra. All Mn–Mn bond lengths are 2.57 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TbInCo2 by Materials Project

TbCo2In crystallizes in the orthorhombic Pmma space group. The structure is three-dimensional. Tb is bonded in a 1-coordinate geometry to seven Co and six equivalent In atoms. There are a spread of Tb–Co bond distances ranging from 2.64–3.10 Å. There are four shorter (3.27 Å) and two longer (3.34 Å) Tb–In bond lengths. There are two inequivalent Co sites. In the first Co site, Co is bonded in a 3-coordinate geometry to three equivalent Tb, four equivalent Co, and two equivalent In atoms. All Co–Co bond lengths are 2.46 Å. Both Co–In bond lengths are 2.74 Å. In the second Co site, Co is bonded to four equivalent Tb, six Co, and two equivalent In atoms to form a mixture of face, edge, and corner-sharing CoTb4In2Co6 cuboctahedra. Both Co–Co bond lengths are 2.52 Å. Both Co–In bond lengths are 2.80 Å. In is bonded in a 12-coordinate geometry to six equivalent Tb, four Co, and two equivalent In atoms. Both In–In bond lengths are 3.33 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TbInRh by Materials Project

TbRhIn crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Tb is bonded in a 11-coordinate geometry to five Rh and six equivalent In atoms. There are four shorter (3.03 Å) and one longer (3.07 Å) Tb–Rh bond lengths. There are two shorter (3.22 Å) and four longer (3.34 Å) Tb–In bond lengths. There are two inequivalent Rh sites. In the first Rh site, Rh is bonded in a 9-coordinate geometry to six equivalent Tb and three equivalent In atoms. All Rh–In bond lengths are 2.85 Å. In the second Rh site, Rh is bonded in a 9-coordinate geometry to three equivalent Tb and six equivalent In atoms. All Rh–In bond lengths are 2.77 Å. In is bonded in a 10-coordinate geometry to six equivalent Tb and four Rh atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TbInPd by Materials Project

TbPdIn crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Tb is bonded in a 11-coordinate geometry to five Pd and six equivalent In atoms. There are four shorter (3.03 Å) and one longer (3.20 Å) Tb–Pd bond lengths. There are two shorter (3.20 Å) and four longer (3.38 Å) Tb–In bond lengths. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 9-coordinate geometry to three equivalent Tb and six equivalent In atoms. All Pd–In bond lengths are 2.78 Å. In the second Pd site, Pd is bonded in a 9-coordinate geometry to six equivalent Tb and three equivalent In atoms. All Pd–In bond lengths are 2.93 Å. In is bonded in a 10-coordinate geometry to six equivalent Tb and four Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TbInIr by Materials Project

TbIrIn crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Tb is bonded in a 11-coordinate geometry to five Ir and six equivalent In atoms. There are four shorter (3.03 Å) and one longer (3.06 Å) Tb–Ir bond lengths. There are two shorter (3.23 Å) and four longer (3.34 Å) Tb–In bond lengths. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 9-coordinate geometry to three equivalent Tb and six equivalent In atoms. All Ir–In bond lengths are 2.78 Å. In the second Ir site, Ir is bonded in a 9-coordinate geometry to six equivalent Tb and three equivalent In atoms. All Ir–In bond lengths are 2.84 Å. In is bonded in a 10-coordinate geometry to six equivalent Tb and four Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TbInAu by Materials Project

TbAuIn crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Tb is bonded in a 11-coordinate geometry to five Au and six equivalent In atoms. There are four shorter (3.11 Å) and one longer (3.14 Å) Tb–Au bond lengths. There are two shorter (3.30 Å) and four longer (3.42 Å) Tb–In bond lengths. There are two inequivalent Au sites. In the first Au site, Au is bonded in a 9-coordinate geometry to three equivalent Tb and six equivalent In atoms. All Au–In bond lengths are 2.86 Å. In the second Au site, Au is bonded in a 9-coordinate geometry to six equivalent Tb and three equivalent In atoms. All Au–In bond lengths are 2.92 Å. In is bonded in a 4-coordinate geometry to six equivalent Tb and four Au atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TbTlPd by Materials Project

TbPdTl crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Tb is bonded in a 11-coordinate geometry to five Pd and six equivalent Tl atoms. There are four shorter (3.07 Å) and one longer (3.17 Å) Tb–Pd bond lengths. There are two shorter (3.23 Å) and four longer (3.38 Å) Tb–Tl bond lengths. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 9-coordinate geometry to three equivalent Tb and six equivalent Tl atoms. All Pd–Tl bond lengths are 2.84 Å. In the second Pd site, Pd is bonded in a 9-coordinate geometry to six equivalent Tb and three equivalent Tl atoms. All Pd–Tl bond lengths are 2.93 Å. Tl is bonded in a 10-coordinate geometry to six equivalent Tb and four Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TbCoSn2 by Materials Project

TbCoSn2 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Tb is bonded in a 12-coordinate geometry to four equivalent Co and ten Sn atoms. All Tb–Co bond lengths are 3.35 Å. There are a spread of Tb–Sn bond distances ranging from 3.30–3.69 Å. Co is bonded in a 9-coordinate geometry to four equivalent Tb and five Sn atoms. There are a spread of Co–Sn bond distances ranging from 2.41–2.56 Å. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 1-coordinate geometry to six equivalent Tb, one Co, and two equivalent Sn atoms. Both Sn–Sn bond lengths are 2.85 Å. In the second Sn site, Sn is bonded in a 12-coordinate geometry to four equivalent Tb and four equivalent Co atoms.

36 MATERIALS SCIENCE↗