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At least 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on LiTb(WO4)2 by Materials Project

LiTbW2O8 is Zircon-derived structured and crystallizes in the tetragonal I-4 space group. The structure is three-dimensional. Li1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are four shorter (2.43 Å) and four longer (2.44 Å) Li–O bond lengths. Tb3+ is bonded in a 8-coordinate geometry to eight O2- atoms. All Tb–O bond lengths are 2.39 Å. There are two inequivalent W6+ sites. In the first W6+ site, W6+ is bonded in a tetrahedral geometry to four equivalent O2- atoms. All W–O bond lengths are 1.83 Å. In the second W6+ site, W6+ is bonded in a tetrahedral geometry to four equivalent O2- atoms. All W–O bond lengths are 1.83 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Tb3+, and one W6+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one Tb3+, and one W6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Gd3YV4O16 by Materials Project

Gd3YV4O16 is Zircon-derived structured and crystallizes in the orthorhombic C222 space group. The structure is three-dimensional. there are two inequivalent Gd3+ sites. In the first Gd3+ site, Gd3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are four shorter (2.36 Å) and four longer (2.48 Å) Gd–O bond lengths. In the second Gd3+ site, Gd3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Gd–O bond distances ranging from 2.35–2.49 Å. Y3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are four shorter (2.33 Å) and four longer (2.47 Å) Y–O bond lengths. There are three inequivalent V5+ sites. In the first V5+ site, V5+ is bonded in a tetrahedral geometry to four O2- atoms. All V–O bond lengths are 1.74 Å. In the second V5+ site, V5+ is bonded in a tetrahedral geometry to four equivalent O2- atoms. All V–O bond lengths are 1.74 Å. In the third V5+ site, V5+ is bonded in a tetrahedral geometry to four equivalent O2- atoms. All V–O bond lengths are 1.74 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one Gd3+, one Y3+, and one V5+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to two Gd3+ and one V5+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to one Gd3+, one Y3+, and one V5+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to two Gd3+ and one V5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KSm(MoO4)2 by Materials Project

KSm(MoO4)2 is Zircon-derived structured and crystallizes in the monoclinic C2 space group. The structure is three-dimensional. K1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 2.67–2.69 Å. Sm3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are four shorter (2.49 Å) and four longer (2.50 Å) Sm–O bond lengths. There are two inequivalent Mo6+ sites. In the first Mo6+ site, Mo6+ is bonded in a tetrahedral geometry to four O2- atoms. All Mo–O bond lengths are 1.81 Å. In the second Mo6+ site, Mo6+ is bonded in a tetrahedral geometry to four O2- atoms. There is two shorter (1.80 Å) and two longer (1.81 Å) Mo–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one K1+, one Sm3+, and one Mo6+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one K1+, one Sm3+, and one Mo6+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one K1+, one Sm3+, and one Mo6+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to one K1+, one Sm3+, and one Mo6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ScCrO4 by Materials Project

ScCrO4 is Zircon structured and crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. Sc3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Sc–O bond distances ranging from 2.16–2.44 Å. Cr5+ is bonded in a tetrahedral geometry to four O2- atoms. There is two shorter (1.70 Å) and two longer (1.74 Å) Cr–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Sc3+ and one Cr5+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Sc3+ and one Cr5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaLa(MoO4)2 by Materials Project

NaLa(MoO4)2 is Zircon-derived structured and crystallizes in the tetragonal I-4 space group. The structure is three-dimensional. Na1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are four shorter (2.60 Å) and four longer (2.61 Å) Na–O bond lengths. La3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are four shorter (2.52 Å) and four longer (2.54 Å) La–O bond lengths. There are two inequivalent Mo6+ sites. In the first Mo6+ site, Mo6+ is bonded in a tetrahedral geometry to four equivalent O2- atoms. All Mo–O bond lengths are 1.80 Å. In the second Mo6+ site, Mo6+ is bonded in a tetrahedral geometry to four equivalent O2- atoms. All Mo–O bond lengths are 1.80 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, one La3+, and one Mo6+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one La3+, and one Mo6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AgMoO4 by Materials Project

MoAgO4 is Zircon-like structured and crystallizes in the tetragonal I-4 space group. The structure is three-dimensional. there are two inequivalent Mo6+ sites. In the first Mo6+ site, Mo6+ is bonded in a tetrahedral geometry to four equivalent O2- atoms. All Mo–O bond lengths are 1.81 Å. In the second Mo6+ site, Mo6+ is bonded in a tetrahedral geometry to four equivalent O2- atoms. All Mo–O bond lengths are 1.81 Å. There are two inequivalent Ag2+ sites. In the first Ag2+ site, Ag2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are four shorter (2.42 Å) and four longer (2.49 Å) Ag–O bond lengths. In the second Ag2+ site, Ag2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are four shorter (2.43 Å) and four longer (2.49 Å) Ag–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one Mo6+ and two Ag2+ atoms. In the second O2- site, O2- is bonded in a 1-coordinate geometry to one Mo6+ and two Ag2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Additive Manufacturing of Energy Harvesting Material System for Active Wireless MEMS Sensors

Combustion systems make up a large sum of the world’s yearly energy production despite advances in renewable energy sources. Precise control of pressure and temperature in combustion chambers allows for lower carbon emissions, and overall higher efficiency. Wireless temperature and pressure sensors are critical for the operation of combustion chambers. Energy harvesters have emerged as a viable way to power wireless sensors when heat and mechanical energy are available. Lithium niobate (LNB), barium titanate (BTO), and lead zirconate titanate (PZT) pyroelectric ceramics were studied and fabricated through additive manufacturing (AM) for use as energy harvesting structures in combustion environments. The electric power generation potential of LNB and PZT ceramics was studied by varying the temperature from 50 to 60 °C and by introducing cyclic compression loads of 2000 N amplitude. It was found that thermal energy conversion had the highest output of 500 nW and that combined thermal and mechanical conversion did not increase the harvesting potential because of the competing contributions of both effects. Powder bed and slurry extrusion AM methods were used to fabricate BTO and PZT ceramic structures. Optimization of the powder-based binder jetting method produced BTO ceramics with a relative density of 36.77% a piezoelectric coefficient of 153 pC/N. The density of the ceramics increased up to 56% when increasing the saturation of binder in the powder to because of liquid phase sintering. Finally, PZT structures were manufactured through AM and fin features were added to the design to enhance the heat transfer along the material. The harvested power density of the flat samples was 3.643 μW/cm 3 and of the finned samples was 3.034 μW/cm3. This research paves the ways for the development of self-powered wireless sensors in critical areas of operation such as combustion.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2022

Glass Crystallization Constraints for WTP LAW Operations: Assessment of Isothermal Treatments on Crystal Formation

Much work has been done to expand the glass composition region available for operation of the Hanford Tank Waste Treatment and Immobilization Plant. This includes the development of updated glass property-composition models as well as constraints. This report supports this effort by suggesting constraints for avoiding excessive, and likely detrimental, crystallization during melter operation while processing advanced low-activity glasses. The constraints target Cassiterite and ZrO 2 -containing phases (ZCP, e.g., Baddeleyite and Zircon) that can form when melter temperatures drop below 1100 °C. These types of crystals were found to be potentially detrimental during processing as they are denser than low-activity waste glass melts; with densities of 6.95 g/cm 3 for Cassiterite and 5.68 g/cm 3 for Baddeleyite (the most prevalent ZCP). Compared to melt densities of approximately 2.65 g/cm 3 . Thus, they have the potential to form during melter idling and settle to the bottom of the melter or inside the melter. If the crystals are present in appreciable amounts, they can result in blockages of the pour-spout riser, which impacts glass pouring and melter operation. Additionally, SnO 2 and ZrO 2 are added to glass formulations to improve glass durability. Their precipitation from the melt may reduce overall glass durability. Using previously acquired results and results from testing during this effort, the following constraints (Table S.1) were determined and are recommended to reduce the risk of forming crystals of the types and concentrations that are likely detrimental to melter operation.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

Online Lead/Water Heat Exchanger Sensor/System Feasibility-PNNL (Final Report)

On-line structural health corrosion monitoring in advanced lead fast reactor heat exchangers and molten salt reactor heat exchangers is desirable for detecting tube degradation prior to leaks that may allow mixing of heat exchanger fluids or release of radiological contamination beyond the design containment boundary. This program, On-Line Lead/Water Heat Exchanger Sensor/System Feasibility – PNNL 76092, demonstrates feasibility for an ultrasonic torsional wave mode sensor attached to the outside of a long (30.5-m) heat exchanger tube in the stagnant flow area where the tube joins a heat exchanger plenum and where it is possible to protect a sensor and cable from high-force flows. The sensor must be cable connected to a monitoring instrument near the heat exchanger. The sensor and cable management approach for periodic in-service inspection will be impractical to implement on existing heat exchangers; rather permanently mounted sensors must be installed in conjunction with heat exchanger fabrication. Previous work has shown low-temperature lead zirconate titanate (PZT) piezoceramic sensors are able to detect anomalies of interest in 3.0-m long tubes. These sensors have hereby been extended to a 30.5-m long tube more representative of commercial power heat exchanger designs. The program will continue to investigate higher temperature piezoelectric ceramics and long-term performance of high temperature adhesives and sealants and mechanical pressure coupling for 350-500 °C lead reactor environments and higher temperature (700 °C) molten salt environments.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2023

Physical and Flow Properties of Glass-Forming Chemicals (V 2 O 5 , SnO, SnO 2 , Cr 2 O 3 , FeCr 2 O 4 , and ZrSiO 4 ) and Mixtures

For an efficient nuclear waste vitrification process at the Waste Treatment and Immobilization Plant (WTP) on the Hanford Site, proper selection and consistent supply of glass-forming chemicals (GFCs) are crucial. Thorough characterization of the GFCs is required to reduce risks in operation of the vitrification facility. Low-activity waste (LAW) will be blended with GFCs to form slurry feeds and then fed to melters and vitrified. To enhance properties of waste glasses, new chemicals are being introduced to the current GFC mixture. In this study, three new GFCs were evaluated for enhanced LAW glass formulations: chromium oxide (Cr 2 O 3 ), vanadium oxide (V 2 O 5 ), and stannic oxide (SnO 2 ). These three oxide components are included in enhanced waste glass formulations, and GFCs with the appropriate physical and flow properties are needed. As a starting point, single metal oxide GFCs, Cr 2 O 3 , V 2 O 5 , and SnO 2 , were sourced and tested. Then, alternative sources of Sn and Cr (SnO and FeCr 2 O 4 ) were tested along with an alternative zircon source (ZrSiO 4 ). This report documents the work performed to collect physical and flow property data on these new GFCs and melter feed slurries generated using these GFCs and simulated low-activity wastes.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2024

New dynamic diamond anvil cell for time-resolved radial x-ray diffraction

The dynamic diamond anvil cell (dDAC) is a recently developed experimental platform that has shown promise for studying the behavior of materials at strain rates ranging from intermediate to quasi-static and shock compression regimes. Combining dDAC with time-resolved x-ray diffraction (XRD) in the radial geometry (i.e., with incident x-rays perpendicular to the axis of compression) enables the study of material properties such as strength, texture evolution, and deformation mechanisms. This work describes a radial XRD dDAC setup at beamline P02.2 (Extreme Conditions Beamline) at DESY’s PETRA III synchrotron. Time-resolved radial XRD data are collected for titanium, zirconium, and zircon samples, demonstrating the ability to study the strength and texture of materials at compression rates above 300 GPa/s. In addition, the simultaneous optical imaging of the DAC sample chamber is demonstrated. The ability to conduct simultaneous radial XRD and optical imaging provides the opportunity to characterize plastic strain and deviatoric strain rates in the DAC at intermediate rates, exploring the strength and deformation mechanisms of materials in this regime.

47 OTHER INSTRUMENTATION↗
DOE OSTI2024

A Theoretical Analysis on the Dynamic Behavior and Electromechanical Response of PZT

Piezoelectric materials are used as a power source in stockpile components for safety and reliability assurances. The objective of this project is to gain insights into the fundamental pressure-induced behavior and electromechanical response of lead zirconate titanate (PZT). Specifically, to establish the basis for an accurate, physics-based material model for robust model-based design to rapidly optimize PZT-based materials and components for performance studies. Established ab-initio methods are used to interrogate and understand the dynamic behavior of PZT as a function of composition (50/50, 65/35, 80/20, 95/5) and dopants (La, Nb) to overcome the costly and time-consuming experimental methodologies. New cold curves for pure and doped single-crystal PZT are obtained as the reference equation-of-state (EOS). A negligible change in the pressure responses was observed for the systems and strains studied. Dielectric and piezoelectric responses of pure and doped single-crystal PZT were also calculated as a function of pressure. For undoped PZT, there is a clear and orderly pressure and composition dependence. For doped PZT, there is a significant increase in the responses, but the behavior is very disordered and inconclusive.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Rare Earth Elements (REE) and Critical Minerals (CM) in Middle Pennsylvanian-Age Coals and Associated Sediments in the Central Appalachian Basin, Eastern U.S.A.

The Central Appalachian Basin (CAB) of Kentucky, Tennessee, West Virginia and Virginia has a long history of coal mining and oil and gas extraction that has empowered the regional and national economies, the development of infrastructure, and a highly trained energy resources work force. As our societal demands for advanced technologies have rapidly increased in recent years, coal-related materials are viewed as an important new unconventional domestic source of critical minerals (CM) that are required for telecommunications, aerospace and transportation industries, electronics, the transition to low-carbon emissions energy production, and many consumer products. Coal-related materials encompass coal, associated sediments, coal mining waste materials, produced waters, and ash residues from coal-fired power plants. An important objective of the Evolve Central Appalachia Project (Evolve CAPP), sponsored by the U.S. Department of Energy (DOE) National Energy Technology Laboratory (NETL) is to assess the quantity and distribution of CM resources in the CAB region. The rare earth elements (REE) are considered highest priority, although other important CM such as niobium, gallium, and zirconium are known to occur in the Middle Pennsylvanian-age coals and sediments. Working with coal industry partners who provided access to drill cores, coal-related sediments and waste materials, over 600 samples have been collected for laboratory analysis, and over 730 materials have been scanned using portable x-ray fluorescence (pXRF) equipment. The application of pXRF provides the means for real-time semiquantitative analysis of CM content at very close spacings (typically 2-3 inch intervals) along drill core and in-situ channel samples that span the roof, coal seam, and floor rock. The comparison of pXRF geochemical data with laboratory results, geologic data, and downhole spectral gamma logs can provide high resolution input to lithologic and depositional models for future CM resource evaluations. The preliminary findings show that pXRF is capable of accurately measuring low concentrations of many of the CM with a high level of confidence (Ba, Cr, Ga, K, Nb, Rb, Sr, Th, Y), whereas for others (La, Ce, Co, Mn, Nd, Ni, Sc, Ti, V) the detection limits are very high or spectral interferences increase the uncertainty. Notably, the mean abundances of Y (34 ppm), La (86 ppm), Ga (40 ppm), and V (146 ppm) in coal underclays in the CAB region are up to 7X enriched compared with the overlying coal. These values also exceed the reported concentrations in published reference materials for upper continental crustal rocks (Rudnick and Gao, 2003), North American Shale Composite (Gromet et al., 1984), and North American coal (Finkelman, 1993). The pXRF data are in part verified by laboratory results that indicate the mean Y abundance (36 ppm) is highly correlated (R2 = 0.807) with total REE (ΣREE). The correlation is even higher (R2 = 0.957) with heavy REE (ΣHREE). Applying these correlations to the pXRF data for the coal underclays, the mean estimated values for ΣREE+Y and ΣHREE+Y are 270 ppm and 58 ppm, respectively. Although these average values are not considered high, the range of Y measured by pXRF in the coal underclays extended as high as 114 ppm, which would suggest ΣREE+Y equal to 847 ppm. The mean abundances of Zr (192 ppm) and Th (21 ppm) in coal underclays are also enriched compared with the overlying coal and these results likely reflect the presence of resistant detrital heavy minerals such as monazite, xenotime, and zircon in the underclay matrix. Several of the profiled coal seams and associated wall rocks contained thin volcanic ash layers up to 4-5 inches in thickness. The extent to which these ash fall layers provided a source for CM under the paleoenvironmental conditions that resulted in coal deposits in the CAB remains to be fully studied. Continuing investigations in the Evolve CAPP study area will include laboratory determinations of mineralogic and clay compositions, and evaluations of CM geochemical mobility in the coal and coal underclays.

Lassetter, Billy↗
DOE OSTI2020

Electrothermal Phenomena in Ferroelectrics

Physical properties of lead-zirconate-titanate (PZT) ceramics change according to the initial electric poling process and electrical boundary conditions. This paper reports the electrothermal, piezothermal, and piezoelectric coupling phenomena in ferroelectrics from thermodynamics viewpoints, in particular, thermal property differences between unpoled and poled PZT’s in the poling direction for open circuit and short circuit conditions. We propose a new terminology, “secondary electrothermal” coupling factor kλ, which is analogous to the electromechanical coupling factor k, relating the elastic compliances under short- and open-circuit conditions, in order to explain the fact that the short-circuit condition exhibited the larger thermal diffusivity than the open-circuit condition. On the other hand, the unpoled specimen exhibits the lowest thermal diffusivity. This tutorial paper was authored for providing comprehensive knowledge on equilibrium and time-dependent thermodynamics in ferroelectrics.

Uchino, Kenji (ORCID:0000000316517912)↗
DOE OSTI2022

U–Pb Geochronology and Stable Isotope Geochemistry of Terrestrial Carbonates, Lower Cretaceous Cedar Mountain Formation, Utah: Implications for Synchronicity of Terrestrial and Marine Carbon Isotope Excursions

The terrestrial Lower Cretaceous Cedar Mountain Formation, Utah, is a critical archive of paleoclimate, tectonics, and vertebrate ecology and evolution. Early Cretaceous carbon cycle perturbations associated with ocean anoxia have been interpreted from this succession, as expressed in stable carbon isotopes. However, refining the timing of the observed stable isotope excursions remains a key challenge in understanding how marine anoxia affects the Earth system, and is ultimately recorded in the terrestrial realm. The geochronology and geochemistry of a terrestrial carbonate near the base of this succession, which potentially records the Ap7 global carbon isotope excursion, is studied here. Petrographic and geochemical analyses are used to test plausible mechanisms for U incorporation into the calcite lattice in this sample. Using these methods, the hypothesis that the incorporation of U was at or close to the timing of carbonate precipitation is evaluated. U–Pb geochronology of calcite indicates a plausible Early Cretaceous age. However, comparison of the new U–Pb ages of calcite with detrital zircon maximum depositional ages immediately beneath the studied sample indicates a disparity in the apparent sedimentation rates if both types of geochronologic information are interpreted as reflecting the timing of sediment deposition. The totality of data supports an early, and high-temperature, diagenetic timing of U incorporation, with potential for minor leaching of U in subsequent fluid–rock interaction. The most likely mechanism for U transport and immobilization in these samples is hydrothermal fluid–rock interaction. Therefore, the radiometric ages, and corresponding stable isotope composition of U-bearing carbonate domains in this sample, indicate early subsurface fluid–rock interactions and not a record of atmosphere–soil geochemical reactions.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Pretreatment of Bituminous Coal By-Products for the Hydrometallurgical Extraction of Rare Earth Elements

Low-temperature plasma (LTP) oxidation has been widely used to study the mineralogy of the mineral matter existing in coal sources. The current study investigated the potential of LTP oxidation as a pre-treatment method to improve rare earth element (REE) leachability from coal and its by-products. Representative density-fractionated samples of Baker and Fire Clay coarse refuse seam materials were ground to a top size of 180 µm and subjected to low-temperature plasma oxidation. Subsequently, the treated samples were leached at 1% w/v solids concentration and 75 °C for 5 h using (i) de-ionized (DI) water, (ii) 0.1 mol/L of ammonium sulfate, and (iii) 1.2 mol/L of sulfuric acid. It was determined that LTP treatment improved REE leaching characteristics, especially the leaching of heavy REEs (HREE), existing in the lighter density fractions of the Baker seam coarse refuse material. For instance, the HREE recovery for the 1.6 specific gravity (SG) float fraction increased from 8% to 33% using 0.1 mol/L of ammonium sulfate solution after 32 h of LTP treatment. This finding indicated that HREEs associated with the organic matter were released by the LTP treatment and adsorbed onto the surfaces of highly negative charged mineral matter and was exchanged with ammonium to allow their recovery. Similarly, when using 1.2 mol/L of sulfuric acid, the HREE recovery increased from 23% to 53% for the 1.6 SG float fraction. Interestingly, LTP oxidation did not provide significant improvement in REE recovery from the 2.2 sink density fractions, which was likely due to its lower organic content. No significant benefits were observed when treating the Fire Clay coarse refuse material, which was likely due to the lack of organic affinity and the difficult-to-leach REE minerals associated with the coal source such as monazite, xenotime, and zircon. Conversely, high-temperature oxidation within a temperature range of 600–750 °C significantly improved REE leaching characteristics for both coal sources. Improvement in REE recovery was due to decarbonization of the material, clay dehydroxylation and subsequent conversion of liberated REE-bearing minerals into a more leachable form. However, increasing the temperature above 800 °C decreased REE recovery due to the conversion of meta-kaolinite into mullite, which is chemically stable.

58 GEOSCIENCES↗
DOE OSTI2021

Sr and Co Vapor-Phase Transport from LSCF Cathodes

A series of tests were performed to differentiate between surface diffusion and vapor-phase diffusion of chemical species from LSCF cathode material at typical sintering temperatures (up to 1100°C) in SOFC production. A GDC source substrate was printed with LSCF and separated by an air gap from a YSZ target substrate. Various geometries with long surface paths were employed to reduce the possibility of surface transport. Sr and Co were detected on the target substrates via energy dispersive spectroscopy (EDS) and x-ray photoelectron spectroscopy (XPS), including spatially resolved XPS. These results support a vapor-phase transport mechanism for Sr and Co. Sintering conditions and barrier layer requirements may need to be revisited to prevent the formation of undesired strontium zirconate at cathode/electrolyte interface due to vapor-phase transport.

vapor phase transport, SOFC cathode, Sr transport↗
DOE OSTI2023

Thermal barrier coatings

High temperature stable thermal barrier coatings useful for substrates that form component parts of engines such as a component from a gas turbine engine exposed to high temperatures are provided. The thermal barrier coatings include a multiphase composite and/or a multilayer coating comprised of two or more phases with at least one phase providing a low thermal conductivity and at least one phase providing mechanical and erosion durability. Such low thermal conductivity phase can include a rare earth zirconate and such mechanical durability phase can include a rare earth a rare earth aluminate. The different phases are thermochemically compatible even at high temperatures above about 1200° C.

Wolfe, Douglas E.↗