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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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All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

SIMULATED LSST SURVEY OF RR LYRAE STARS THROUGHOUT THE LOCAL GROUP

We report on a study to determine the efficiency of the Large Synoptic Survey Telescope (LSST) to recover the periods, brightnesses, and shapes of RR Lyrae stars' light curves in the volume extending to heliocentric distances of 1.5 Mpc. We place the smoothed light curves of 30 type ab and 10 type c RR Lyrae stars in 1007 fields across the sky, each of which represents a different realization of the LSST sampling cadences, and that sample five particular observing modes. A light curve simulation tool was used to sample the idealized RR Lyrae stars' light curves, returning each as it would have been observed by LSST, including realistic photometric scatter, limiting magnitudes, and telescope downtime. We report here the period, brightness, and light curve shape recovery as a function of apparent magnitude and for survey lengths varying from 1 to 10 years. We find that 10 years of LSST data are sufficient to recover the pulsation periods with a fractional precision of {approx}10{sup -5} for {>=}90% of ab stars within Almost-Equal-To 360 kpc of the Sun in Universal Cadence fields and out to Almost-Equal-To 760 kpc for Deep Drilling fields. The 50% completeness level extends to Almost-Equal-To 600 kpc and Almost-Equal-To 1.0 Mpc for the same fields, respectively. For virtually all stars that had their periods recovered, their light curve shape parameter {phi}{sub 31} was recovered with sufficient precision to also recover photometric metallicities to within 0.14 dex (the systematic error in the photometric relations). With RR Lyrae stars' periods and metallicities well measured to these distances, LSST will be able to search for halo streams and dwarf satellite galaxies over half of the Local Group, informing galaxy formation models and providing essential data for mapping the Galactic potential. This study also informs the LSST science operations plan for optimizing observing strategies to achieve particular science goals. We additionally present a new [Fe/H]-{phi}{sub 31} photometric relation in the r band and a new and generally useful metric for defining period recovery for time domain surveys.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Demographic and genetic consequences of a steelhead supplementation program

Abstract Objective Supplementation of naturally spawning populations by the addition of hatchery-spawned individuals is commonly conducted for recovery of threatened and endangered populations and to support harvest opportunities. Our objective was to evaluate whether the use of a juvenile captive broodstock and an integrated paradigm could increase returns of steelhead, the anadromous form of Rainbow Trout Oncorhynchus mykiss, while avoiding negative genetic impacts commonly associated with hatchery propagation. Methods We analyzed 291 genetic markers in adult steelhead returning to an integrated population in southwest Washington over the course of 15 years. Reproductive success (RS) of fish spawning in the natural environment was evaluated by origin (hatchery versus natural) and return year. Data were then pooled over years to maximize sample sizes for comparing RS estimates among groups (i.e., estimation of relative reproductive success [RRS]). Result We observed a weak relationship between RS and origin (male p = 0.347; female p = 0.066), but a significant relationship between RS and return year (male p < 0.001, η2 = 0.896; female p ⟨ 0.001, η2 = 0.867) (i.e., hatchery- and natural-origin fish did well or poorly together each year). Estimates of RRS for fish spawned in the hatchery ranged from 2.4 to 6.4, indicating that fish spawned in the hatchery produced more returning adult progeny than did fish allowed to spawn in the natural environment. Estimates of RRS were ⟨1.0 for hatchery-origin fish spawning in the natural environment, but the difference was nonsignificant for males and marginally significant for females. Hatchery-origin fish exhibited reduced genetic diversity as well as evidence of increased temporal population structure. Conclusion We conclude that the program was successful in achieving an increase in adult returns but not in avoiding negative genetic effects on the population and that any lasting impacts of supplementation remain to be determined.

Smith, Christian T. (ORCID:0000000240522669)↗
DOE OSTI2012

Molecular beam mass spectrometry with tunable vacuum ultraviolet (VUV) synchrotron radiation

Tunable soft ionization coupled to mass spectroscopy is a powerful method to investigate isolated molecules, complexes and clusters and their spectroscopy and dynamics.[1-4] Fundamental studies of photoionization processes of biomolecules provide information about electronic structure of these systems. Furthermore determinations of ionization energies and other properties of biomolecules in the gas phase are not trivial, and these experiments provide a platform to generate these data. We have developed a thermal vaporization technique coupled with supersonic molecular beams that provides a gentle way to transport these species into the gas phase. Judicious combination of source gas and temperature allows for formation of dimers and higher clusters of the DNA bases. The focus of this particular work is on the effects of non-covalent interactions, i.e., hydrogen bonding, stacking, and electrostatic interactions, on the ionization energies and proton transfer of individual biomolecules, their complexes and upon micro-hydration by water.[1, 5-9] We have performed experimental and theoretical characterization of the photoionization dynamics of gas-phase uracil and 1,3-methyluracil dimers using molecular beams coupled with synchrotron radiation at the Chemical Dynamics Beamline[10] located at the Advanced Light Source and the experimental details are visualized here. This allowed us to observe the proton transfer in 1,3-dimethyluracil dimers, a system with pi stacking geometry and with no hydrogen bonds[1]. Molecular beams provide a very convenient and efficient way to isolate the sample of interest from environmental perturbations which in return allows accurate comparison with electronic structure calculations[11, 12]. By tuning the photon energy from the synchrotron, a photoionization efficiency (PIE) curve can be plotted which informs us about the cationic electronic states. These values can then be compared to theoretical models and calculations and in turn, explain in detail the electronic structure and dynamics of the investigated species [1, 3].

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Removal of Technetium-99 on Ion Exchange Resin - A Case Study at 200 West Pump and Treat - 17303

The 200 West Pump and Treat (P and T), on the U.S. Department of Energy's Hanford Site and operated by CH2M HILL Plateau Remediation Company, has a 9,464 liters per minute capacity designed to capture and treat an 8 km{sup 2} contaminated groundwater plume and reduce the mass of contaminants of concern (COCs) by 95 percent in 25 years. The plume is a complex mix of contaminants including technetium-99 (Tc-99), uranium, carbon tetrachloride, chromium, hexavalent chromium, nitrate, and iodine-129 (I-129). Ion exchange (IX), a common treatment approach for Tc-99 used by many nuclear remediation sites, is used to remove uranium and Tc-99 at 200 West P and T. The IX vessels are arranged in a sequence of three to provide a lead, lag and polish vessel. Tc-99 concentrations are monitored monthly to assure good performance of the system. Performance tracking revealed surprising results. On October 14, 2015, the resin in the lead vessels released Tc-99 at concentrations greater than what was being fed. Although Tc-99 was captured by the downstream lag and polish vessels, the facility staff grabbled with the sudden release of Tc-99 entertaining a variety of scenarios that might result in sudden failure of the IX processes. Subsequent sampling indicated Tc-99 removal began a steady return to normal. The incident raised many questions, chief among them whether the same events could recur and undermine Tc-99 treatment. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2025

Counterpart identification and classification for eRASS1 and characterisation of the active galactic nuclei content

Context. Accurately accounting for the Active Galactic Nucleus (AGN) phase in galaxy evolution requires a large, clean AGN sample. This is now possible with SRG/eROSITA, which completed its first all-sky X-ray survey (eRASS1) on June 12, 2020. The public Data Release 1 (DR1, Jan 31, 2024) includes 930,203 sources from the western Galactic hemisphere. Aims. The data enable the selection of a large AGN sample and the discovery of rare sources. However, scientific return depends on accurate characterisation of the X-ray emitters, requiring high-quality multi-wavelength data. This paper presents the identification and classification of optical and infrared counterparts to eRASS1 sources. Methods. Counterparts to eRASS1 X-ray point sources were identified using Gaia DR3, CatWISE2020, and Legacy Survey DR10 (LS10) with the Bayesian NWAY algorithm and trained priors. Sources were classified as Galactic or extragalactic via a machine-learning model combining optical/IR and X-ray properties, trained on a reference sample. For extragalactic LS10 sources, photometric redshifts were computed using CIRCLEZ. Results. Within the LS10 footprint, all 656,614 eROSITA/DR1 sources have at least one possible optical counterpart; ∼570 000 are extragalactic and likely AGN. Half are new detections compared to AllWISE, Gaia, and Quaia AGN catalogues. Gaia and CatWISE2020 counterparts are less reliable, due to the survey’s shallowness and the limited amount of features available to assess the probability of being an X-ray emitter. In the Galactic plane, where the overdensity of stellar sources also increases the chance of associations, using conservative reliability cuts, we identified approximately 18 000 Gaia and 55 000 CatWISE2020 extragalactic sources. Conclusions. We have released three high-quality counterpart catalogues – plus the training and validation sets – as a benchmark for the field. These datasets have many applications, but in particular, they empower researchers to build AGN samples tailored for completeness and purity, accelerating the hunt for the Universe’s most energetic engines.

X-rays: general↗
DOE OSTI2021

Automatic detection of impact craters on Al foils from the Stardust interstellar dust collector using convolutional neural networks

NASA's Stardust mission utilized a sample collector composed of aerogel and aluminum foil to return cometary and interstellar particles to Earth. Analysis of the aluminum foil begins with locating craters produced by hypervelocity impacts of cometary and interstellar dust. Interstellar dust craters are typically less than one micrometer in size and are sparsely distributed, making them difficult to find. In this paper, we describe a convolutional neural network based on the VGG16 architecture that achieves high specificity and sensitivity in locating impact craters in the Stardust interstellar collector foils. Finally, we evaluate its implications for current and future analyses of Stardust samples.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

Binary pseudorandom test standard to determine the modulation transfer function of optical microscopes

This work reports on the development of a binary pseudo-random test sample optimized to calibrate the MTF of optical microscopes. The sample consists of a number of 1-D and 2-D patterns, with different minimum sizes of spatial artifacts from 300 nm to 2 microns. We describe the mathematical background, fabrication process, data acquisition and analysis procedure to return spatial frequency based instrument calibration. We show that the developed samples satisfy the characteristics of a test standard: functionality, ease of specification and fabrication, reproducibility, and low sensitivity to manufacturing error. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Effect of pH on hydrogen pick-up and corrosion in zircaloy-4

Thermal Desorption Spectroscopy (TDS) has been used to investigate the hydrogen pick-up behaviour in different samples of Zircaloy-4. This includes as-received, cold rolled, hydrogen charged, and autoclave-oxidised in pure water and at an elevated pH (with 50% deuterated water) compared to commercial reactors. A characteristic desorption peak for hydrogen has been found at about 650 Celsius degrees, which is theorised to come from hydrides. Cold rolled samples show the same general shape spectrum as the as-received samples, with more hydrogen detected per unit volume of sample. This suggests more hydrogen is in trapping sites or outward diffusion paths are facilitated by dislocations, since no more hydrogen has been added. The peak broadens towards higher temperature, which indicates that additional dislocations could provide trapping sites with a slightly higher energy than the average in the as-received samples. The hydrogen charged samples form a hydride rim, which contains much more hydrogen than the as-received samples. The peak broadens but on average does not shift. The surface oxide, when present, acts as a barrier to the desorption of hydrogen, until the temperature rises enough for the oxygen to migrate into the bulk. The oxide itself only contains a small amount of hydrogen, as is evidenced when the oxide layer is removed, whereupon the desorption peak returns to the characteristic shape seen in as-received samples. Samples oxidised in pure water exhibit a slightly higher oxidation rate, and pass through kinetic transition much earlier than samples exposed to an elevated pH. Before transition pH has little effect on the hydrogen pick-up. After transition the hydrogen pick-up is much higher in pure water, which implies that the H{sup +} concentration in the environment affects hydrogen pickup at this stage. The elevated pH samples showed peaks for D-H and D{sub 2}, which follow the H{sub 2} peaks. The hydrogen content in these samples increases at around 70% of the time to the first transition. This may correlate with development of through-thickness percolation paths, which could lead to the pH inside cracks being modified to a lower value, increasing the availability of H{sup +} ions. (authors)

36 MATERIALS SCIENCE↗
DOE OSTI2020

Crewmember microbiome may influence microbial composition of ISS habitable surfaces

The International Space Station (ISS) is a complex built environment physically isolated from Earth. Assessing the interplay between the microbial community of the ISS and its crew is important for preventing biomedical and structural complications for long term human spaceflight missions. In this study, we describe one crewmember’s microbial profile from body swabs of mouth, nose, ear, skin and saliva that were collected at eight different time points pre-, during and post-flight. Additionally, environmental surface samples from eight different habitable locations in the ISS were collected from two flights. Environmental samples from one flight were collected by the crewmember and samples from the next flight were collected after the crewmember departed. The microbial composition in both environment and crewmember samples was measured using shotgun metagenomic sequencing and processed using the Livermore Metagenomics Analysis Toolkit. Ordination of sample to sample distances showed that of the eight crew body sites analyzed, skin, nostril, and ear samples are more similar in microbial composition to the ISS surfaces than mouth and saliva samples; and that the microbial composition of the crewmember’s skin samples are more closely related to the ISS surface samples collected by the crewmember on the same flight than ISS surface samples collected by other crewmembers on different flights. In these collections, species alpha diversity in saliva samples appears to decrease during flight and rebound after returning to Earth. This is the first study to compare the ISS microbiome to a crewmember’s microbiome via shotgun metagenomic sequencing. We observed that the microbiome of the surfaces inside the ISS resemble those of the crew’s skin. These data support future crew and ISS microbial surveillance efforts and the design of preventive measures to maintain crew habitat onboard spacecraft destined for long term space travel.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

Adaptive Sample Preparation and Target Fabrication for High-Throughput Materials Science

High-repetition-rate brilliant and coherent light sources are significantly increasing the rate at which scientific experiments can be performed. An investment in transformative technologies to make samples of condensed matter could enable a paradigm shift for that field or open new exciting frontiers in high-energy density science (HEDS). This will especially be true for dynamic materials in extremes research or HEDS, where the repetition rate for placing samples into extreme environments is increasing and the samples or targets are irreversibly destroyed in each experiment. Research teams that are able to implement solutions to all aspects of the experimental process and enable a paradigm of high-throughput science will have the greatest success and impact. There are two different directions for adaptive samples. One is research when the number of experiments can be greatly increased with increased volume, such as in high energy density science. The other is when flexibility and agility can aid Bayesian optimization computational methods and speed up the discovery process, as with materials science. Conducting a similar equation-of-state (EOS) experiment took three years on the OMEGA laser facility, compared to five days of shifts at the LCLS XFEL. New materials with improved properties have been found by guided optimization of experimental science. Adaptive sample preparation and target fabrication can create a tremendous return on scientific investment. High-throughput enabling precision science is also a desirable goal. To address these issues, we sought a diverse set of innovative participants who had ideas of how to achieve this paradigm shift. We invited 42 researchers from a variety of disciplines and fields to attend a workshop in College Station, Texas, May 14–16, 2019. Many of the participants had never been in the same room before, and most found it very exciting to hear about new and different research. The goal was twofold: to define the challenges, i.e., “what would we like to be able to do and why it is difficult to do so,” and to describe the progress, approaches and capabilities, as well as the vision, “what we could do if we had more support.”

36 MATERIALS SCIENCE↗
DOE OSTI2024

Enabling dynamic 3D coherent diffraction imaging via adaptive latent space tuning of generative autoencoders

Abstract Coherent diffraction imaging (CDI) is an advanced non-destructive 3D X-ray imaging technique for measuring a sample’s electron density. The main challenge of CDI is loss of phase information in diffraction intensity measurements, resulting in lengthy iterative reconstruction processes that can return non-unique solutions, which pose challenges for experiments attempting to track dynamic sample evolution through multiple states. As the increased brightness of fourth-generation light sources enables faster sample measurements and drives operando experiments with Bragg CDI, there is a growing need for faster reconstruction techniques that can keep pace. We have developed an adaptive generative autoencoder approach for uniquely tracking a sample’s electron density as it dynamically evolves. Our approach adaptively tunes the low-dimensional latent embedding of a generative autoencoder, enabling a computationally efficient manner to account for time-varying shifting distributions in real-time. Analytic proof of convergence is provided as well as numerical demonstration of sample tracking with noisy measurements.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2014

Neutron Fluence Measurements for the UCF HSIS Experiment in ATR

The University of Central Florida (UCF) experiments were irradiated in the Hydraulic Shuttle Irradiation System (HSIS) of the Advanced Test Reactor (ATR) at Idaho national Laboratory (INL) to study the effects of how low neutron fluence on metallic fuels. Four samples were irradiated for 20 days from 2/20/2014 to 3/12/2014 and four additional samples were irradiated for 2 days from 3/17/2014 to 3/19/2014. All eight of the samples included neutron fluence capsules that were previously prepared at PNNL. After irradiation, the neutron fluence monitors were returned to Pacific Northwest National Laboratory (PNNL) for analysis to determine the neutron fluence that was received by each sample.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

Method for high-throughput micro-sampling analysis of electrochemical process salts

A method and apparatus for analyzing molten salt electrolyte. The method includes extracting a sample of a molten salt electrolyte from an electrorefiner or other process vessel or conduit; generating droplets from the sample, where the droplets are at a first temperature; transporting the droplets to detectors, where during transport, the droplets attain a second temperature that is lower than the first temperature; analyzing the droplets at or below the second temperature; and returning the droplets to the process. The apparatus includes a droplet generator; a sample transport mechanism; and at least one detector positioned above the sample transport mechanism.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2018

Macquarie Island Cloud and Radiation Experiment (MICRE) Ice Nucleating Particle Measurements Field Campaign Report

The U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) user facility Macquarie Island Cloud and Radiation Experiment (MICRE) Ice Nucleating Particle Measurements campaign was aligned as a supplemental activity with the second year of the overall MICRE campaign. The purpose of the supplemental campaign was to provide a first-ever annual cycle of ice nucleating particle (INP) measurements at a Southern Ocean (SO) site, toward the investigation/characterization of sources of INPs in the marine boundary layer as being from the production or primary sea spray aerosol (SSA) emissions versus other long-range transport influences. Furthermore, measuring the variability in INPs seasonally in this region, as this may relate to meteorology and ocean biological processes, is expected to help constrain (via parameterizations) numerical model simulations of cloud phase and regional climate. In concert with other SO studies during the time frame of the campaign (March 2017 to March 2018), MICRE sought to evaluate the hypotheses that SSA INPs represent the major INP source in the SO and, due to their generally less efficient INP activation properties compared to terrestrial sources, that they may directly influence the persistence of supercooled clouds in a unique manner for this climatic region. These measurements supplemented the original deployment of primarily radiation measurements provided in the ARM MICRE request and the associated Australian Antarctic Division (AAD) Antarctic Clouds and Radiation Experiment (ACRE). Assistance and collaboration was obtained from the AAD, the Commonwealth Scientific and Industrial Research Organization (CSIRO) and the Australian Bureau of Meteorology (BOM). Follow-up plans will include investigations with their additional aerosol, cloud, and radiative transfer measurements. AAD also saw to the transport to Australia and storage of filters at the end of the campaign. The added effort involved an average of twice-weekly collections (a 48-hour and a 72-hour collection) of pre-sterilized, open-faced, polycarbonate filter samples for post-processing of INP number concentrations and tests to analyze the nature of INP sources. Collections were made by AAD technician Emry Thaggard Crocker after online training from our team. Images of the filter sampler and site are shown in Figure 1. Sampling occurred from an approximate elevation of 4m MSL. Filters were returned frozen to Colorado State University (CSU) at the end of the campaign. Initial processing to obtain INP temperature spectra (0 to -28°C) of the concentrations of INPs active via the immersion freezing mechanism were conducted using the CSU ice spectrometer (IS) instrument systems (Hiranuma et al. 2015; McCluskey et al. 2018). In this method, particles are first removed from filters using ultrapure water while under mechanical agitation. Arrays of the particle suspensions from a portion of filter rinses are then cooled to obtain immersion freezing data per volume of water, and finally are related to sampling volumes to obtain numbers per volume of air following the analysis methods of Vali (1971). A total of 103 filters were collected, including blanks at selected intervals throughout the project. For archival and completion of tasks under this ARM proposal, nearly half of the filter collections (46) were processed for basic temperature spectra, and half of these (23) were also tested for microbial/proteinaceous contributions toward INPs via 95°C pre-treatment of portions of the original suspensions.

Southern Ocean, aerosols, marine clouds, MARCUS ca↗
DOE OSTI2020

Impacts of advanced diesel combustion operation and fuel formulation on soot nanostructure and reactivity

Advanced diesel combustion, accomplished via a single pulse fuel injection and high levels of exhaust gas recirculation (referred to as “PCCI”, partially-premixed charge compression ignition), is shown to be a path to reduce oxides of nitrogen and particulate matter simultaneously. This is well established in the literature. Less established is the extent to which such dilute combustion processes influence soot formation and affect soot that is emitted from diesel engines under such combustion modes. This work focuses on characterization of the nanostructure and oxidative reactivity of soot generated by a light-duty turbodiesel engine operating under a PCCI combustion mode, a dilute, low-temperature combustion process. Previous work on a type of PCCI combustion, referred to as high-efficiency clean combustion (HECC), showed soot samples having a fullerenic nanostructure, characterized by high levels of tortuosity of the fringe layers as seen in transmission electron micrograph images and as quantified using an image processing algorithm. Thermogravimetric analysis of the HECC mode soot samples showed that they displayed higher rates of oxidation than soot samples from a conventional diesel combustion mode. The present work returns to PCCI combustion, considering the timing of the main fuel injection, and the effects of operating on fuels rich in n-alkanes, particularly a fuel produced from a low temperature Fischer-Tropsch process (LTFT) and a renewable diesel fuel (RD) produced via hydrodeoxygenation of a plant oil. PCCI combustion conditions yield soot that shows higher reactivity compared to soot from the conventional combustion mode regardless of fuel type. LTFT and RD fuels produce soots with lower reactivity compared to ULSD. Soots produced from PCCI combustion have higher surface oxygen concentration and higher proportion of amorphous carbon. In addition, TEM images show that PCCI soots from all three fuels have smaller primary particle and particle aggregate sizes, and smaller graphene layers. These properties explain the higher reactivity of soot from PCCI combustion. The less reactive soots, which are produced from LTFT and RD fuel under conventional combustion, show internal burning during oxidation. However, soots with higher reactivity which are produced from late injection PCCI combustion and ULSD show shrinking core oxidation, most likely because of their overall amorphous structure.

42 ENGINEERING↗
DOE OSTI2012

Synthesis of homogeneous Ca{sub 0.5}Sr{sub 0.5}FeO{sub 2.5+{delta}} compound using a mirror furnace method

Graphical abstract: X-ray diffraction pattern indexing of Ca{sub 0.5}Sr{sub 0.5}FeO{sub 2.5+{delta}} powder sample obtained by mirror furnace method after thermal treatment. Highlights: Black-Right-Pointing-Pointer A homogenous compound Ca{sub 0.5}Sr{sub 0.5}FeO{sub 2.5+{delta}} has been synthesized for the first time by a mirror furnace method. Black-Right-Pointing-Pointer Ca{sub 0.5}Sr{sub 0.5}FeO{sub 2.5+{delta}} powder sample is perfectly homogenous, confirmed by X-ray diffraction, Raman spectroscopy and EDS technique. Black-Right-Pointing-Pointer The thermal treatment of Ca{sub 0.5}Sr{sub 0.5}FeO{sub 2.5+{delta}} powder sample can increase their average grain sizes. -- Abstract: A new synthesis method using melting zone technique via the double mirror furnace around 1600 Degree-Sign C is used to obtain homogenous brownmillerite compounds Ca{sub 1-x}Sr{sub x}FeO{sub 2.5+{delta}} in the range 0.3 {<=} x {<=} 0.7. These compounds play important role in understanding the mystery of the oxygen diffusion in the perovskite-related oxides. We have successfully solved the miscibility gap problem by synthesizing a good quality of homogenous powder samples of Ca{sub 0.5}Sr{sub 0.5}FeO{sub 2.5+{delta}} compound. Our result was confirmed by X-rays diffraction, Raman spectroscopy and energy dispersive spectroscopy analysis. Thermal treatment was also applied until 800 Degree-Sign C under vacuum to confirm again the homogeneity of powder samples, improve its quality and show that no decomposition or return to form Ca- and Sr-enriched microdomains takes place as a result of phase separation.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Impact of UV Pulsed Laser Radiation and of the Electron Flow on Dielectric States of Polymer Composite Nanomaterial Based on LDPE Matrix

The influence of the soft electron flow and irradiating pulsed UV laser on dielectric states of polymer composite nanomaterial based on LDPE matrix is experimentally studied. It was shown that irradiation of the samples LDPE–ZnO by electron beam (10 keV) for 10–15 minutes gives rise the appearance of the horizontal portion of the temperature dependence of capacitance (permittivity) and to memory effect (slow relaxation of dielectric situation within a few days). Irradiation with pulsed UV laser of the LDPE–CdS sample allows you to switch into a conducting state and return it to their original state upon application of a weak electric field. The observed phenomena may find practical applications for the polymer electronic memories and switching devices.

36 MATERIALS SCIENCE↗