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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Growth of New High-Quality and Large-Size Single Crystals via High Pressure Floating-Zone Technique

This award supports experimental materials physics research on a class of technologically relevant materials that cannot form under ambient conditions. With the complementary expertise at Louisiana State University (LSU) and infrastructure at Oak Ridge National Laboratory (ORNL), single crystals of these materials will be synthesized using the high-pressure floating-zone technique. Our ability to grow high-quality single crystals will facilitate advanced characterization of these materials and improve the scientific outcomes. In addition to in-house material characterization, the principle investigator will partner with scientists at ORNL and Brookhaven National Laboratory (BNL) to tackle materials problems using the state-of-the-art characterization techniques. This will allow us to explore the fundamental physics underlying the emergent phenomena only seen in materials prepared under extreme conditions. Our ultimate goal is to address one of the grand challenges of materials science: how do complex phenomena emerge from simple ingredients? The proposed project will also spearhead a unique opportunity to train “new breed” scientists, co-advised by experts at both LSU and U. S. Department of Energy National Laboratories. They will be essential for expanding materials physics research with ability to grow crystals, characterize their properties, and design new materials -- an imperative skill that is scarce in the U. S. scientific community.

36 MATERIALS SCIENCE↗
NASA NTRS1983

Properties of large nearly perfect crystals at very low temperatures

A liquid helium cryostat of a size and construction unavailable commercially, was built for use in measuring the Q of several materials at milli-Kelvin temperatures. The design and testing of the cryostat is described as well as the design of the experiment vacuum chamber and adaptor for the dilution refrigerator insert. Theory, design, and testing are also discussed for the magnetic coils built to levitate the materials so as to isolate them and increase the measured Q. A four point suspension with capacitor end plates as the transducer was used to obtain preliminary Q measurements of 6061 aluminum alloy and single crystal silicon. Results are tabulated.

Davis, W.↗
DOE OSTI2024

Thermal Conversion of Ultrathin Nickel Hydroxide for Wide Band Gap 2D Nickel Oxides

Wide band gap (WBG) semiconductors (E g > 2.0 eV) are integral to the advancement of next-generation electronics, optoelectronics, and power industries owing to their capability for high-temperature operation, high breakdown voltage, and efficient light emission. Enhanced power efficiency and functional performance can be attained through miniaturization, specifically via the integration of device fabrication into a two-dimensional (2D) structure enabled by WBG 2D semiconductors. However, as an essential subgroup of WBG semiconductors, 2D transition metal oxides (TMOs) remain largely underexplored in terms of physical properties and applications in 2D optoelectronic devices, primarily due to the scarcity of sufficiently large 2D crystals. Thus, our goal is to develop synthesis pathways for 2D TMOs possessing large crystal domains (e.g., >10 μm), expanding the 2D TMO family and providing insights for future engineering of 2D TMOs. Here, we demonstrate the synthesis of WBG 2D nickel oxide (NiO) (E g > 2.7 eV) thermally converted from 2D nickel hydroxide (Ni(OH) 2 ) with a lateral domain size larger than 10 μm. Moreover, the conversion process is investigated using various microscopic techniques, such as atomic force microscopy, Raman spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy, providing significant insights into morphology and structural variations under different oxidative conditions. The electronic structure of the converted Ni x O y is further investigated using multiple soft X-ray spectroscopies, such as X-ray absorption and emission spectroscopies.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

In situ counter-diffusion crystallization and long-term crystal preservation in microfluidic fixed targets for serial crystallography

Compared with batch and vapor diffusion methods, counter diffusion can generate larger and higher-quality protein crystals yielding improved diffraction data and higher-resolution structures. Typically, counter-diffusion experiments are conducted in elongated chambers, such as glass capillaries, and the crystals are either directly measured in the capillary or extracted and mounted at the X-ray beamline. Despite the advantages of counter-diffusion protein crystallization, there are few fixed-target devices that utilize counter diffusion for crystallization. In this article, different designs of user-friendly counter-diffusion chambers are presented which can be used to grow large protein crystals in a 2D polymer microfluidic fixed-target chip. Methods for rapid chip fabrication using commercially available thin-film materials such as Mylar, propylene and Kapton are also detailed. Rules of thumb are provided to tune the nucleation and crystal growth to meet users' needs while minimizing sample consumption. These designs provide a reliable approach to forming large crystals and maintaining their hydration for weeks and even months. This allows ample time to grow, select and preserve the best crystal batches before X-ray beam time. Importantly, the fixed-target microfluidic chip has a low background scatter and can be directly used at beamlines without any crystal handling, enabling crystal quality to be preserved. The approach is demonstrated with serial diffraction of photoactive yellow protein, yielding 1.32 Å resolution at room temperature. Fabrication of this standard microfluidic chip with commercially available thin films greatly simplifies fabrication and provides enhanced stability under vacuum. These advances will further broaden microfluidic fixed-target utilization by crystallographers.

Liu, Zhongrui↗
DOE OSTI2016

Focusing of white synchrotron radiation using large-acceptance cylindrical refractive lenses made of single – crystal diamond

Large-aperture cylindrical refractive lenses were manufactured by laser cutting of single-crystal diamond. Five linear single lenses with apertures of 1 mm and the depth of the structure of 1.2 mm were fabricated and tested at the ESRF ID06 beamline performing the focusing of white-beam synchrotron radiation. Uniform linear focus was stable during hours of exposure, representing such lenses as pre-focusing and collimating devices suitable for the front-end sections of today synchrotron radiation sources.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1975

Experimental modeling of the cooling history of Apollo 12 olivine basalts

An analog of the Apollo 12 olivine vitrophyres has been crystallized in a 1-atm gas-mixing furnace at cooling rates ranging between 1250 and 0.7 C/hr and isothermally at degrees of supercooling ranging from 10 C to 325 C. Mineral chemistry, crystal shapes, grain sizes and textures are systematically related to cooling rate and degree of supercooling. At linear cooling rates not exceeding 40 C/hr the texture is porphyritic - large olivine crystals are set in a groundmass of finer-grained pyroxene, plagioclase, and ilmenite; a later generation of olivine never crystallizes. There are three shapes of olivine crystals in the Apollo 12 olivine vitrophyres: glomerocrysts of subhedral crystals, large subequant skeletons, and highly elongate skeletons. These result from three generations of nucleation and a two-stage cooling history - a slow preeruption stage and a rapid continuously increasing posteruption stage. It seems likely that the Apollo 12 olivine basalt magmas were erupted with olivine crystals in suspension. The nucleation temperature of olivine in cooling-rate experiments is dependent on the experimental technique, and hence results of cooling experiments should be applied with caution.

Donaldson, C. H.↗
NASA NTRS1988

Growth and characterization of large YBa2Cu3O(7-x) single crystals

Centimeter-sized crystal plates of YBa2Cu3O(7-x) have been obtained using a bulk composition and method described by Schneemeyer at al. (1987) modified for growth in a pure oxygen atmosphere. A porous MgO crucible and long soak time promote large crystals. Mg was not detectable in the crystals. Electron microbeam analysis using a 60 A monochromator crystal for the oxygen determination gave the composition Y(1.05)Ba(2.02)Cu(2.94)O(6.52 + or - 0.06). As-grown crystals from the melt surface exhibit a fairly sharp Tc with zero resistance at 80 K, and show complex twinning and crack patterns. Optical micrographs of a lightly polished surface normal to the c-axis of a 3-mm crystal delineate twinning and fine scale microcracking; this crystal surface now has a zero resistance at 68 K. Microhardness measurements and microfracture observations indicate intrinsic properties that may inhibit or impede large scale manufacture of electronic ceramics.

Keester, Kenneth L.↗
NASA NTRS1985

Mechanical testing of large thallium doped sodium iodide single crystals

The findings of mechanical tests performed on five thallium-doped sodium iodide NaI(Tl) crystals are presented. These crystals are all in the shape of circular flat plates, 20.0 in. in diameter an d0.5 in. thick. The test setup, testing procedure, and the test data are presented. Large crystals exhibit a high degree of material plasticity, as well as a much higher strength than previously anticipated, on the order of 500 psi. Also revealed from the testing is the fact that crystal with a large number of grain boundaries developed less plasticity, and therefore less permanent deformation, than those with fewer grain boundaries.

Lee, H. M.↗
DOE OSTI2022

Use of wire grid polarizers with liquid crystal display for large-volume stereolithography

Spatial light modulators that use liquid crystal devices (LCDs) to pattern ultraviolet light for vat polymerization suffer from a few limitations: limited range of wavelengths that can be patterned, low damage threshold for incoming light, and low efficiency of light transmission. A monochrome LCD can more efficiently transmit useful wavelengths of light for stereolithography (365–405 nm) than a color LCD, but it still contains two absorptive film polarizers that suffer from the aforementioned limitations. Wire grid polarizers reflect rather than absorb the blocked polarizations of light, resulting in a higher intensity damage threshold. They can also polarize lower wavelength light that is limited only by the wire pitch. In this work, this research investigates the effects of replacing an LCD’s film polarizers with wire grid polarizers to enable polarization and patterning of high intensity UV light, resulting in shorter curing times and the ability to print a wider range of stereolithography feedstocks.

42 ENGINEERING↗
DOE OSTI2016

Synthesis, crystal growth, structural and magnetic characterization of NH{sub 4}MCl{sub 2}(HCOO), M=(Fe, Co, Ni)

An ambient-pressure solution route and an improved solvothermal synthetic method have been developed to produce polycrystalline powders and large single crystals of NH{sub 4}MCl{sub 2}(HCOO) (M=Fe, Co, Ni). The magnetic structure of the 1D linear chain compound NH{sub 4}FeCl{sub 2}(HCOO) has been determined by low-temperature neutron powder diffraction, revealing ferromagnetic intra-chain interactions and antiferromagnetic inter-chain interactions. The newly-reported Co and Ni analogs are isostructural with NH{sub 4}FeCl{sub 2}(HCOO), but there are significant differences in the magnetic properties of each compound; the Ni analog behaves similarly to the Fe compound but with stronger magnetic coupling, exhibiting antiferromagnetic ordering (T{sub N}=8.5 K) and a broad metamagnetic transition between 2 and 5 T, while the Co analog does not order magnetically above 2 K, despite strong antiferromagnetic nearest-neighbor interactions. - Graphical abstract: Large single crystals of NH{sub 4}MCl{sub 2}(HCOO) (M=Fe, Co, Ni), which adopt a 1D zig-zag chain structure, can be grown via a solvothermal method. Neutron diffraction experiments revealed that the magnetic structure of the iron compound exhibits ferromagnetic intra-chain coupling and antiferromagnetic inter-chain coupling. - Highlights: • Large crystals of NH{sub 4}MCl{sub 2}(HCOO) (M=Fe, Co, Ni) have been grown solvothermally. • The magnetic structure of M=Fe was solved by low-temperature neutron diffraction. • NH{sub 4}FeCl{sub 2}(HCOO) exhibits FM intra-chain and AFM inter-chain interactions. • NH{sub 4}CoCl{sub 2}(HCOO) exhibits no 3D magnetic ordering above 2 K. • NH{sub 4}NiCl{sub 2}(HCOO) exhibits AFM ordering (T{sub N}=8.5 K) and FM intra-chain interactions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Growth Kinetics and Morphology of Barite Crystals Derived from Face-Specific Growth Rates

Here we investigate the growth kinetics and morphology of barite (BaSO 4 ) crystals by measuring the growth rates of the (001), (210), (010), and (100) surfaces using vertical scanning interferometry. Solutions with saturation indices 1.1, 2.1, and 3.0 without additional electrolyte, in 0.7 M NaCl, or in 1.3 mM SrCl2 are investigated. Face-specific growth rates are inhibited in the SrCl 2 solution relative to a solution without electrolyte, except for (100). Contrarily, growth of all faces is promoted in the NaCl solution. The variation of face-specific rates is solution-specific, which leads to a. change of the crystal morphology and overall growth rate of crystals. The measured face-specific growth rates are used to model the growth of single crystals. Modeled crystals have a morphology and size similar to those grown from solution. Based on the model the time dependence of surface area and growth rates is analyzed. Growth rates change with time due to surface area normalization for small crystals and large growth intervals. By extrapolating rates to crystals with large surfaces areas, time-independent growth rates are 0.783, 2.96, and 0.513 mmol∙m -2 ∙h -1 , for saturation index 2.1 solutions without additional electrolyte, NaCl, and SrCl 2 , respectively.

36 MATERIALS SCIENCE↗