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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Additive manufacturing of amorphous metal soft magnetic composites

Soft magnet alloys are used as magnetic cores for electric motors, transformers, wind turbines and other power generation systems. Soft magnetic cores are expensive and time consuming to manufacture in the complex shapes required for next-generation devices using conventional press and sinter powder metallurgy. The objective of this effort is to additively manufacture high performance soft magnets, with reduced cost and reduced material waste and 10x lower energy (core) loss at the high operating frequencies of many electric machines. Laser powder bed fusion additive manufacturing is used as the fabrication method. Electrical steel and amorphous alloys atomized powders are used as a feedstock materials. Magnetic cores are printed in topology optimized structures such as the Hilbert curve because this has been shown to reduce energy losses by minimizing the eddy currents that circulate within the magnet at high frequencies. In our project, we succeed in printing FeSi 3.5wt% and FeSi 6.5wt% electrical steels, and iron-based soft magnetic amorphous alloys in the shape of Hilbert and Peano curve topology optimized structures. We found that the Peano curve has a higher cut-off frequency than the Hilbert curve, and that amorphous alloys have high cut-off frequencies and higher mechanical hardness than electrical steels. Processing conditions such as laser power, scan speed, and hatching pattern were optimized to achieve high density prints, and optimize magnetic performance. We find that the printing of amorphous alloy soft magnetic cores may be technoeconomically feasible for large scale applications such as transformers, for which supply chain issues and the labor costs of manual fabrication of magnetic cores is prohibitive in some cases.

36 MATERIALS SCIENCE↗
NASA NTRS1983

Solar system ice - Amorphous or crystalline?

The meteoritic bombardment of icy surfaces is discussed, focusing on the formation of amorphous ice and its thermal, mechanical, and optical properties. A numerical code has been developed for evaluating the ratio of the volume of the melted and vaporized ice target to the volume of the projectile that has impacted the surface and left a crater. However, water will only vaporize with impact speeds over 4 to 6 km/sec, and subsequent condensation into ice below 150 K will produce amorphous ice. A denser form of amorphous ice exists below 10 K, with the transition into a crystalline form occurring above 150 K. Maximum impact velocities have been defined for all major bodies in the solar system, with the finding that crystalline ice will form in the crater while amorphous ice will form on the ejecta. The amount of each is dependent on the ratio of solidified water to condensed water vapor and on the fraction of solid ejecta.

Smoluchowski, R.↗
NASA NTRS1984

The U.S. and Japanese amorphous silicon technology programs A comparison

The U.S. Department of Energy/Solar Energy Research Institute Amorphous Silicon (a-Si) Solar Cell Program performs R&D on thin-film hydrogenated amorphous silicon for eventual development of stable amorphous silicon cells with 12 percent efficiency by 1988. The Amorphous Silicon Solar Cell Program in Japan is sponsored by the Sunshine Project to develop an alternate energy technology. While the objectives of both programs are to eventually develop a-Si photovoltaic modules and arrays that would produce electricity to compete with utility electricity cost, the U.S. program approach is research oriented and the Japanese is development oriented.

Shimada, K.↗
NASA NTRS1989

Experimental studies of gas trapping in amorphous ice and thermal modelling of comets: Implications for Rosetta

The trapping of mixtures of CO, CH4, N2 and Ar in amorphous water ice was studied experimentally. It is shown that the ice particles could not have been formed at a higher temperature and, subsequently, cool down. Experiments where ice was deposited at elevated temperatures, then cooled down and gas was flowed into the ice, showed that the amount of trapped gas depends only on the highest temperature at which the ice was formed, or resided, prior to cooling and gas flow into it. Consequently, the cometary ice had to be formed at approx. 48 K and the ice is therefore amorphous. The thermal profile of a comet in Halley's orbit was calculated, including the build-up of an insulating dust layer. It was found that an insulating dust layer a few cm thick is enough to choke most of the water emission from the surface. A similar thermal model was calculated for comet P/Temple-1, a candidate for both CRAF and Rosetta (CNSR) missions. The temperature at a depth of 10 m is approx. 160 K for all models considered and, hence, the ice at this depth is crystalline. A crystalline ice layer 40 to 240 m thick was found to overly the gas-laden amorphous ice. Consequently, it should be difficult for the probes of the two comet missions to sample pristine amorphous ice, unless they are aimed at the bottom of an active crater.

Bar-Nun, Akiva↗
NASA NTRS1991

Processing Bi-Pb-Sr-Ca-Cu-O superconductors from amorphous state

The bismuth based high T sub c superconductors can be processed via an amorphous Bi-Pb-Sr-Ca-Cu oxide. The amorphous oxides were prepared by melting the constituent powders in an alumina crucible at 1200 C in air followed by pouring the liquid onto an aluminum plate, and rapidly pressing with a second plate. In the amorphous state, no crystalline phase was identified in the powder x ray diffraction pattern of the quenched materials. After heat treatment at high temperature the amorphous materials crystallized into a glass ceramic containing a large fraction of the Bi2Sr2Ca2Cu3O(x) phase T sub c = 110 K. The processing method, crystallization, and results of dc electrical resistivity and ac magnetic susceptibility measurements are discussed.

Chiang, C. K.↗
NASA NTRS1995

An electron tunneling study of superconductivity in amorphous Sn(sub 1-x)Cu(sub x) thin films

The amorphous phase of Sn would have a superconducting transition temperature near 8 K, much higher than that of crystalline Sn with T(sub c) = 3.5 K. To obtain the amorphous phase, however, it is necessary to use a Sn alloy, usually Cu, and quench condense the alloy films onto a liquid He temperature substrate. Alloying with Cu reduces the superconducting transition temperature almost linearly with Cu concentration with an extrapolation of T(sub c) to zero for x = 0.85. Analysis of the tunneling characteristics between a normal metal electrode with an insulating barrier and superconducting amorphous Sn-Cu films provides detailed information on the changes in the electron-phonon coupling which determines T(sub c) in these alloys. The change from very strong electron-phonon coupling to weak-coupling with the increase in Cu content of amorphous Sn-Cu alloys for the range 0.08 is less than or equal to x is less than or equal to 0.41 is presented and discussed in terms of theories of electron-phonon coupling in disordered metals.

Naugle, D. G.↗
NASA NTRS2004

Microcrystals and Amorphous Material in Comets and Primitive Meteorites: Keys to Understanding Processes in the Early Solar System

Comets, fine-grained matrices of chondrites, and chondritic interplanetary dust particles (IDPs) are each composed of both crystalline and amorphous silicates. The primitive solar nebula, in which comets and asteroids accreted, was formed from the collapsed core of a Giant Molecular Cloud, that, in turn, condensed from materials present in the interstellar medium (ISM). Despite observations that reveal the presence of crystalline magnesium silicate minerals in the shells of very high mass-loss-rate stars [1,2], typical silicate grains in the ISM are most likely to be amorphous, given their relatively long residence time in such a high radiation environment. An upper limit of ~3% crystalline grains can be derived from their non-detection in spectra of ISM solids [3]. If the vast majority of grains that enter the primitive solar nebula are amorphous, then the observation of crystalline dust in comets and primitive chondrite matrices indicates the action of specific processes required to transform the amorphous starting materials into the crystals that are observed.

Nuth, J. A.↗
NASA NTRS2006

New Optical Constants for Amorphous and Crystalline H2O-ice

We have used the infrared spectra of laboratory ices to calculate the real and imaginary indices of refraction for amorphous and crystalline H2O-ice. We create H2O-ice samples in vacuum (approx. 10(exp ^-8)Torr). We measure the thickness of the sample by reflecting a He-Ne laser off of the sample and counting interference fringes as it grows and then collect transmission spectra of the samples in the wavelength range 1.25-22 micrometers. Using the ice thickness and transmission spectrum we calculate the imaginary part of the index of refraction. A Kramers-Kronig calculation is then used to calculate the real part of the index of refraction (Berland et al. 1994; Hudgins et al. 1993). These optical constants can be used to create model spectra for comparison to spectra from Solar System objects. We will summarize the differences between the amorphous and crystalline H2O-ice spectra. These include weakening of features and shifting of features to shorter wavelength in amorphous H,O-ice spectra. We will also discuss methods of using band area ratios to quickly estimate the fraction of amorphous to crystalline H2O-ice. We acknowledge financial support from the NASA Origins of the Solar System Program, the NASA Planetary Geology and Geophysics Program, and the NASA Postdoctoral Program.

Mastrapa, Rachel↗
NASA NTRS2009

Amorphous Silk Fibroin Membranes for Separation of CO2

Amorphous silk fibroin has shown promise as a polymeric material derivable from natural sources for making membranes for use in removing CO2 from mixed-gas streams. For most applications of silk fibroin, for purposes other than gas separation, this material is used in its highly crystalline, nearly natural form because this form has uncommonly high tensile strength. However, the crystalline phase of silk fibroin is impermeable, making it necessary to convert the material to amorphous form to obtain the high permeability needed for gas separation. Accordingly, one aspect of the present development is a process for generating amorphous silk fibroin by treating native silk fibroin in an aqueous methanol/salt solution. The resulting material remains self-standing and can be prepared as thin film suitable for permeation testing. The permeability of this material by pure CO2 has been found to be highly improved, and its mixed-gas permeability has been found to exceed the mixed-gas permeabilities of several ultrahigh-CO2-permeable synthetic polymers. Only one of the synthetic polymers poly(trimethylsilylpropyne) [PTMSP] may be more highly permeable by CO2. PTMSP becomes unstable with time, whereas amorphous silk should not, although at the time of this reporting this has not been conclusively proven.

Aberg, Christopher M.↗
NASA NTRS2010

Mimas: Preliminary Evidence For Amorphous Water Ice from VIMS

We have conducted a statistical clustering analysis (1,2) on a mosaic of VIMS data cubes obtained on February 13, 2010, for Saturn s satellite Mimas. Seven VIMS cubes were geometrically projected and re-sampled to a common spatial resolution. The clustering technique consists of a partitioning algorithm coupled to a criterion that prevents sub-optimal solutions and tests for the influence of random noise in the measurements. The clustering technique is agnostic about the meaning of the clusters, and scientific interpretation requires their a posteriori evaluation. The preliminary results yielded five clusters, demonstrating that spectral variability across Mimas surface is statistically significant. The ratios of the means calculated for each of the clusters show structure within the 1.6- micron water ice band, as well as the shape and the central wavelength of the strong ice band at 2 micron, that map spatially in patterns apparently related to the topography of Mimas, in particular certain regions in and around Herschel crater. The mean spectra of the five clusters, show similarities with laboratory spectra of amorphous and crystalline H2O ice (3) that are suggestive of the presence of an amorphous ice component in certain regions of Mimas, notably on the central peak of Herschel, on the crater floor, and in faults surrounding the crater. This may represent a mixture of both ice phases, or perhaps a layer of amorphous ice on a base of crystalline ice. Another possible occurrence of amorphous ice appears southwest of Herschel, close to the south pole.

Cruikshank, Dale P.↗
NASA NTRS2016

MSL SAM-Like Evolved Gas Analyses of Si-rich Amorphous Materials

Chemical and mineralogical analyses of several samples from Murray Formation mudstones and Stimson Formation sandstones by the Mars Science Laboratory (MSL) revealed the presence of Si-rich amorphous or poorly ordered materials. It is possible to identify the presence of high-SiO2 vs. lower SiO2 amorphous materials (e.g., basaltic glasses), based on the position of the resulting wide diffraction features in XRD patterns from the Chemistry and Mineralogy (CheMin) instrument, but it is not possible to distinguish between several candidate high-SiO2 amorphous materials such as opal-A or rhyolitic glass. In the Buckskin (BS) sample from the upper Murray Formation, and the Big Sky (BY) and Greenhorn (GH) samples from the Stimson Formation, analyses by the Sample Analysis at Mars (SAM) instrument showed very broad H2O evolutions during sample heating at temperatures >450-500degC which had not been observed from previous samples. BS also had a significant broad evolution <450-500degC. We have undertaken a laboratory study targeted at understanding if the data from SAM can be used to place constraints on the nature of the amorphous phases. SAM-like evolved gas analyses have been performed on several opal and rhyolitic glass samples. Opal-A samples exhibited wide <500degC H2O evolutions, with lesser H2O evolved above ~500degC. H2O evolution traces from rhyolitic glasses varied, having either two broad H2O peaks, <300degC and >500degC, or a broad peak centered around 400degC. For samples that produced two evolutions, the lower temperature peak is more intense than the higher temperature peak, a trend also exhibited by opal-A. This trend is consistent with data from BS, but does not seem consistent with data from BY and GH which evolved most of their H2O >500degC. It may be that dehydration of opal-A and/or rhyolitic glass can result in some preferential loss of lower temperature H2O, to produce traces that more closely resemble BY and GH. This is currently under investigation and results will be reported.

McAdam, Amy↗
NASA NTRS2017

Infrared Spectra and Band Strengths of Amorphous and Crystalline N2O

Infrared transmission spectra from 4000 to 400 cm (exp -1), and associated band strengths and absorption coefficients, are presented for the first time for both amorphous and crystalline N2O. Changes in the spectra as a function of ice thickness and ice temperature are shown. New measurements of density, refractive index, and specific refraction are reported for amorphous and crystalline N2O. Comparisons are made to published results, and the most-likely reason for some recent disagreements in the literature is discussed. As with CO2, its isoelectronic congener, the formation of amorphous N2O is found to require greater care than the formation of amorphous solids from more-polar molecules.

Infrared spectra↗
NASA NTRSDate not supplied

TEM and XRD Investigation of Impact Glass Alteration Products: Amorphous Materials, Phyllosilicates and Everything in Between

Impact cratering is one of the most ubiquitous geologic processes shaping the surface of all solid bodies in our solar system. Impacts are also a major source of clay minerals and poorly crystalline, clay-like materials on Earth and Mars[1,2].These phyllosilicates and related clay-like phases comprise an incredibly complex group of materials, and their characterization, even in controlled laboratory settings, remains a challenging endeavor. The nature and origin of clay minerals and amorphous materials on Mars, which form a major component (~20-70 wt %) of rock and soil samples in Gale Crater as determined by the CheMin instrument on Curiosity, have remained ambiguous[3]. These amorphous phases likely fall on a spectrum between pristine volcanic and/or impact-produced primary materials and clay minerals and related phases formed from aqueous alteration. Amorphous materials are common weathering products in terrestrial sediments, soils, and paleosols [e.g., 4,5].Primary impact materials (glass, melt rocks)are comparable in some ways to those generated volcanically [6], and so it may be possible that an amorphous component is preserved within altered impactites. There are hundreds of thousands of impact craters on Mars, and Curiosity and Perseverance are currently exploring ancient impact craters. We hypothesize that the sediments and lithologies in Gale and Jezero Craters and elsewhere contain altered impact products; it is therefore important to better understand the composition and structure of these materials. Here we present the first results from a study characterizing materials produced from impact glass alteration–clay minerals, poorly crystalline/amorphous materials–in terrestrial craters using Transmission Electron Microscopy (TEM), powder X-ray diffraction (pXRD)and chemical (EDS) analysis.

Impact crater↗
NASA NTRS2026

Polarized Resonant Soft X-ray Scattering (P-RSoXS) as a New Technique for Characterizing Amorphous Astromaterials

In the coming years, samples will be returned from several asteroids, the lunar surface, and the first material returned directly from the Martian surface. Previous in-situ and remote studies indicate these samples will contain abundant amorphous or weakly crystalline materials. However, detailed characterization and quantification of these amorphous materials remains challenging. Conventional techniques, including electron microscopy and X-ray diffraction, provide important information on material structure, but are generally limited to crystalline materials. Polarized resonant soft X-ray scattering (P-RSoXS) is a synchrotron-based X-ray scattering technique that has been used to characterize and quantify weakly crystalline systems, including soft materials. This research aims to translate this technique to geologic and extraterrestrial materials, building off the knowledge of using P-RSoXS to interrogate soft materials. P-RSoXS is well-suited to interrogate geologic materials, which are often multiphase, heterogeneous systems with crystalline and amorphous components, and domain sizes on the order of tens of nanometers. It is anticipated that future work will help reveal new chemical and structural information in geologic materials. Maturation of this preliminary work to develop P-RSoXS to characterize astromaterial-relevant samples will provide new understanding of the secondary processes responsible for the development of amorphous astromaterials and further elucidate our knowledge of the geologic history and past alteration processes.

Joshua H Litofsky↗
DOE OSTI2025

Impact of Interfacial Structure on Heterogeneous Nucleation of Amorphous Carbonates

For this work, classical molecular dynamics simulations were performed to provide physical insight into the impact of interfacial structure on the heterogeneous nucleation of amorphous calcium carbonate (ACC, CaCO 3 ·H 2 O) and amorphous magnesium carbonate (AMC, MgCO 3 ·H 2 O) by using α-quartz as a model substrate. Interfacial structure and energies were computed for ACC and AMC in contact with the (100), (001), and (101) α-quartz surfaces. The simulations showed α-quartz surfaces drew water molecules out of the carbonate nuclei to form a partial hydration layer. The formation of a partial hydration layer and its disruption to the ACC/AMC structure meant the α-quartz–ACC/AMC interfaces were not energetically favored relative to separate α-quartz–water and ACC/AMC–water interfaces and, thus, homogeneous ACC/AMC nucleation was favored over heterogeneous nucleation. The CMD simulations hence provided an atomic-level explanation for a reported nonclassical growth mechanism whereby carbonate minerals grow via homogeneous nucleation and subsequent surface attachment of amorphous intermediates.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Electron Microscopy Approaches to Unraveling the Structure of Amorphous Materials

Determining atomic structures in crystalline materials—where atoms are arranged in rigid, periodic lattices—has been highly successful using probes such as electrons, X-rays, and neutrons. In contrast, amorphous materials, despite their ubiquity and technological importance, remain far more challenging to characterize with comparable accuracy and precision. This review highlights existing, emerging, and potential (scanning) transmission electron microscopy ((S)TEM) techniques for probing short- and medium-range order in amorphous materials. Approaches ranging from high-resolution (S)TEM imaging and selected electron diffraction pattern to four-dimensional STEM (4D-STEM) based pair distribution function, fluctuation electron microscopy, tomography, ptychography, and spectroscopic methods are discussed, emphasizing their ability to provide complementary insights across multiple length scales—from sub-angstrom local environments to nanometer-scale correlations. Here, we further explore the promise of multimodal and correlative strategies, as well as the growing role of machine learning and physics-informed AI in enabling real-time, quantitative interpretation of complex structural signatures. Together, these advances point toward a future where electron microscopy not only reveals the hidden order in amorphous systems but also establishes robust structure–property relationships, paving the way for materials innovation in disordered matter.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2025

Bulk nanocrystalline Al–Mg–Y alloys with amorphous grain boundary complexions display high strength and compressive plasticity

Although nanocrystalline alloys regularly exhibit high strengths, their use in structural applications often face challenges due to sample size limitations, unstable microstructures, and the limited ability to plastically deform. The incorporation of amorphous grain boundary complexions has been proposed to address these issues, by simultaneously stabilizing nanocrystalline grain structures for scale-up processing and improving alloy toughness. In the present study, the mechanical behavior of bulk nanocrystalline Al–Mg–Y is examined with macroscale compression testing, probing a length scale that is relevant to real-world structural applications. Bulk samples were fabricated via a simple powder metallurgy approach, with different hot-pressing temperatures and durations employed for consolidation in order to investigate microstructural and property evolution. All of the specimens contained primary face-centered cubic Al and secondary Al 4 C 3 and Al 3 Y phases, with the Al 3 Y particles exhibiting two populations of small equiaxed and larger elongated particles. Appreciable plasticity was measured along with high ultimate stresses over 800 MPa due to the presence of amorphous grain boundary complexions. Microstructural characterization of fracture surfaces revealed that the area fraction of dimpled regions increased with longer hot-pressing time. Most importantly, the elongated Al 3 Y particles formed regular cellular patterns with increasing hot-pressing time, delaying shear localization and significantly enhancing plasticity. The hierarchy present in the microstructure of the Al–Mg–Y alloy, from amorphous grain boundary complexions to secondary phases, gives rise to excellent bulk mechanical properties, which are attractive for structural applications.

Bulk nanocrystalline alloy↗
DOE OSTI2025

Kinetics of amorphous defect phases measured through ultrafast nanocalorimetry

Recognition of the role of extended defects on local phase transitions has led to the conceptualization of the defect phase, localized thermodynamically stable interfacial states that have since been applied in a myriad of material systems to realize significant enhancements in material properties. Here, we explore the kinetics of grain boundary confined amorphous defect phases, utilizing the high temperature and scanning rates afforded by ultrafast differential scanning calorimetry to apply targeted annealing/quenching treatments at high rates capable of capturing the kinetic behavior. Four Al-based nanocrystalline alloys, including two binary systems, Al–Ni and Al–Y, and two ternary systems, Al–Mg–Y and Al–Ni–Y, are selected to probe the materials design space (enthalpy of mixing, enthalpy of segregation, chemical complexity) for amorphous defect phase formation and stability, with correlative transmission electron microscopy applied to link phase evolution and grain stability to nanocalorimetry signatures. A series of targeted isothermal annealing heat treatments is utilized to construct a Time–Temperature-Transformation curve for the Al–Ni system, from which a critical cooling rate of 2400 °C/s was determined for the grain boundary confined disordered-to-ordered transition. Finally, a thermal profile consisting of 1000 repeated annealing sequences was created to quantify the recovery of the amorphous defect phase following sequential annealing treatments, with results indicating remarkable microstructural stability after annealing at temperatures above 90% of the melting temperature. This work contributes to a deeper understanding of grain boundary localized thermodynamics and kinetics, with potential implications for the design and optimization of advanced materials with enhanced stability and performance.

Amorphous defect phases↗