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DOE OSTI2020

Materials Data on La4Cu4SeS3O4 by Materials Project

(LaO)4Cu4SeS3 crystallizes in the tetragonal P4mm space group. The structure is two-dimensional and consists of one Cu4SeS3 sheet oriented in the (0, 0, 1) direction and one LaO sheet oriented in the (0, 0, 1) direction. In the Cu4SeS3 sheet, Cu1+ is bonded to one Se2- and three S2- atoms to form a mixture of edge and corner-sharing CuSeS3 tetrahedra. The Cu–Se bond length is 2.50 Å. All Cu–S bond lengths are 2.42 Å. Se2- is bonded in a 12-coordinate geometry to four equivalent Cu1+ atoms. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a 4-coordinate geometry to four equivalent Cu1+ atoms. In the second S2- site, S2- is bonded in a 4-coordinate geometry to four equivalent Cu1+ atoms. In the LaO sheet, there are three inequivalent La3+ sites. In the first La3+ site, La3+ is bonded in a 4-coordinate geometry to four equivalent O2- atoms. All La–O bond lengths are 2.37 Å. In the second La3+ site, La3+ is bonded in a 4-coordinate geometry to four equivalent O2- atoms. All La–O bond lengths are 2.36 Å. In the third La3+ site, La3+ is bonded in a 4-coordinate geometry to four equivalent O2- atoms. All La–O bond lengths are 2.37 Å. O2- is bonded to four La3+ atoms to form a mixture of edge and corner-sharing OLa4 tetrahedra.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on La2Zn(SeO)2 by Materials Project

(LaO)2ZnSe2 crystallizes in the orthorhombic Cmce space group. The structure is two-dimensional and consists of two LaO sheets oriented in the (1, 0, 0) direction and two ZnSe2 sheets oriented in the (1, 0, 0) direction. In each LaO sheet, there are three inequivalent La3+ sites. In the first La3+ site, La3+ is bonded in a 4-coordinate geometry to four equivalent O2- atoms. There are two shorter (2.38 Å) and two longer (2.39 Å) La–O bond lengths. In the second La3+ site, La3+ is bonded in a 4-coordinate geometry to four equivalent O2- atoms. There are two shorter (2.38 Å) and two longer (2.40 Å) La–O bond lengths. In the third La3+ site, La3+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of La–O bond distances ranging from 2.35–2.41 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four La3+ atoms to form a mixture of edge and corner-sharing OLa4 tetrahedra. In the second O2- site, O2- is bonded to four La3+ atoms to form a mixture of edge and corner-sharing OLa4 tetrahedra. In each ZnSe2 sheet, there are two inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded to four Se2- atoms to form a mixture of edge and corner-sharing ZnSe4 tetrahedra. There are two shorter (2.50 Å) and two longer (2.53 Å) Zn–Se bond lengths. In the second Zn2+ site, Zn2+ is bonded to four Se2- atoms to form corner-sharing ZnSe4 tetrahedra. All Zn–Se bond lengths are 2.51 Å. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a distorted water-like geometry to two equivalent Zn2+ atoms. In the second Se2- site, Se2- is bonded in a 2-coordinate geometry to two equivalent Zn2+ atoms. In the third Se2- site, Se2- is bonded in a distorted water-like geometry to two Zn2+ atoms.

36 MATERIALS SCIENCE↗

NASA NTRS2019

Assessment of the Biomass Productivity Decline in the Lower Mekong Basin

This study aimed to delineate the geographic hotspots of negative trends in biomass productivity in the Lower Mekong Basin countries (Vietnam, Cambodia, Laos, and Thailand) and identify correlated regional environmental and anthropogenic factors. A long-term time-series (1982–2015) of Normalized Difference Vegetation Index at a resolution of approximately 9.16 km x 9.16 km was used to specify the areas with significant decline or increase in productivity. The relationships between vegetation changes and land attributes, such as climate, population density, soil/terrain conditions, and land-cover types, were examined. Rainfall time-series maps were used to identify areas that might have been affected by land degradation from those correlated with rainfall. Most of the detected potentially degraded areas were found in Cambodia, the Northwest and the Highland of Vietnam, the Northern Mountains of Thailand and Laos, and the mountainous border between Laos, Vietnam, and Cambodia. About 15% of the total land area of these four countries experienced a reduction in biomass productivity during the 34-year study period. The map of hotspots of changes in productivity can be used to direct further studies, including those at finer spatial resolution that may support policy makers and researchers in targeting the strategies for combating land degradation.

land degradation↗

DOE OSTI2021

Electrochromic Properties of Perovskite NdNiO 3 Thin Films for Smart Windows

Semiconductors with electrically tunable band gaps are of great interest in controlling transparency to electromagnetic radiation. Thin films of perovskite nickelate NdNiO 3 (NNO), a class of correlated oxides, were deposited on single-crystal (LaAlO 3 (LAO)) and polycrystalline (fluorine-doped tin oxide-coated glass (FTO)) substrates by magnetron sputtering, chemical solution deposition (CSD), and atomic layer deposition (ALD). Their electrochromic behaviors were investigated using a three-electrode setup in basic (KOH solution, pH = 12) electrolyte. During bleaching/coloration process, the proton intercalation/deintercalation and simultaneous electron compensation in the NNO lattice under electrical bias led to crossover of the material between the pristine-conducting phase (Ni 3+ ) and the strongly correlated insulating phase (Ni 2+ ), which serves as the working principle for electrochromic (tunable opacity in the visible range) behavior. Cyclic voltammetry (CV) scans demonstrate that NNO films are electrochemically stable in basic solutions for all three film deposition methods explored here. CV scans at varying rates enabled the extraction of diffusion coefficient of protons in thin film NNO, which is similar to 10 –7 cm 2 s –1 among all films studied. Large light transmittance modulation by bleaching and coloration was observed on films grown on both LAO and FTO substrates, suggesting its potential as an electrochromic material candidate for smart windows and optical shutter applications. Here, porous NNO films obtained by chemical solution deposition tend to demonstrate stronger electrochromic activity than dense films grown by sputtering or ALD.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Strain- and thickness-dependent magnetic properties of epitaxial La 0.67 Sr 0.33 CoO 3 /La 0.67 Sr 0.33 MnO 3 bilayers

Magnetic properties and interfacial phenomena of epitaxial perovskite oxides depend sensitively on parameters such as film thickness and strain state. In this work, epitaxial La0 .67 Sr 0.33 CoO 3 (LSCO)/La 0.67 Sr 0.33 MnO 3 (LSMO) bilayers were grown on NdGaO 3 (NGO) and LaAlO 3 (LAO) substrates with a fixed LSMO thickness of 6 nm, and LSCO thickness (t LSCO ) varying from 2 to 10 nm. Soft x-ray magnetic spectroscopy revealed that magnetically active Co 2+ ions that strongly coupled to the LSMO layer were observed below a critical t LSCO for bilayers grown on both substrates. On LAO substrates, this critical thickness was 2 nm, above which the formation of Co 2+ ions was quickly suppressed leaving only a soft LSCO layer with mixed valence Co 3+ /Co 4+ ions. The magnetic properties of both LSCO and LSMO layers displayed strong t LSCO dependence. This critical t LSCO increased to 4 nm on NGO substrates, and the magnetic properties of only the LSCO layer displayed t LSCO dependence. A non-magnetic layer characterized by Co 3+ ions and with a thickness below 2 nm exists at the LSCO/substrate interface for both substrates. Therefore, the results contribute to the understanding of interfacial exchange spring behavior needed for applications in next generation spintronic and magnetic memory devices.

36 MATERIALS SCIENCE↗

DOE OSTI2025

Nanoscale control of LaAlO 3 /SrTiO 3 conductance beyond the polar catastrophe

Conductive atomic force microscope (c-AFM) lithography can be utilized to create a wide range of LaAlO 3 /SrTiO 3 (LAO/STO)-based nanoelectronic devices in a reconfigurable manner. Experiments were generally performed with intrinsically insulating LAO/STO heterostructures, with LAO thickness less than the critical value at which a polar catastrophe takes place [<4 unit cell (u.c.)]. Here, we use inductively coupled plasma reactive ion etching (ICPRIE) to fabricate c-AFM “canvases” on intrinsically conducting LAO/STO samples with ≥4 u.c. LAO. We observe that its interfacial two-dimensional electron gas (2DEG) can be pinched off and then switched back on by c-AFM lithography. Nanowires created with initially conductive LAO/STO interfaces have an order-of-magnitude longer lifetime in ambient conditions, when compared to an identically created 3.4 u.c. LAO/STO nanowire. We also demonstrate key nanoscale properties such as ballistic transport in a quasi-one-dimensional electron waveguide at a 5 u.c. LAO/STO interface. This approach frees c-AFM-written nanodevice designs from time constraints in air associated with <4 u.c. LAO/STO heterostructures.

36 MATERIALS SCIENCE↗

DOE OSTI2023

Understanding the transient large amplitude oscillatory shear behavior of yield stress fluids

A full understanding of the sequence of processes exhibited by yield stress fluids under large amplitude oscillatory shearing is developed using multiple experimental and analytical approaches. A novel component rate Lissajous curve, where the rates at which strain is acquired unrecoverably and recoverably are plotted against each other, is introduced and its utility is demonstrated by application to the analytical responses of four simple viscoelastic models. Using the component rate space, yielding and unyielding are identified by changes in the way strain is acquired, from recoverably to unrecoverably and back again. The behaviors are investigated by comparing the experimental results with predictions from the elastic Bingham model that is constructed using the Oldroyd–Prager formalism and the recently proposed continuous model by Kamani, Donley, and Rogers in which yielding is enhanced by rapid acquisition of elastic strain. The physical interpretation gained from the transient large amplitude oscillatory shear (LAOS) data is compared to the results from the analytical sequence of physical processes framework and a novel time-resolved Pipkin space. The component rate figures, therefore, provide an independent test of the interpretations of the sequence of physical processes analysis that can also be applied to other LAOS analysis frameworks. Each of these methods, the component rates, the sequence of physical processes analysis, and the time-resolved Pipkin diagrams, unambigiously identifies the same material physics, showing that yield stress fluids go through a sequence of physical processes that includes elastic deformation, gradual yielding, plastic flow, and gradual unyielding.

Kamani, Krutarth M. (ORCID:0000000338975420)↗

DOE OSTI2020

Materials Data on LaCoPO by Materials Project

LaCoPO is Parent of FeAs superconductors structured and crystallizes in the tetragonal P4/nmm space group. The structure is two-dimensional and consists of one CoP sheet oriented in the (0, 0, 1) direction and one LaO sheet oriented in the (0, 0, 1) direction. In the CoP sheet, Co2+ is bonded to four equivalent P3- atoms to form a mixture of distorted edge and corner-sharing CoP4 tetrahedra. All Co–P bond lengths are 2.22 Å. P3- is bonded in a 4-coordinate geometry to four equivalent Co2+ atoms. In the LaO sheet, La3+ is bonded in a 4-coordinate geometry to four equivalent O2- atoms. All La–O bond lengths are 2.36 Å. O2- is bonded to four equivalent La3+ atoms to form a mixture of edge and corner-sharing OLa4 tetrahedra.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on LaCuSeO by Materials Project

LaCuOSe is Parent of FeAs superconductors structured and crystallizes in the tetragonal P4/nmm space group. The structure is two-dimensional and consists of one CuSe sheet oriented in the (0, 0, 1) direction and one LaO sheet oriented in the (0, 0, 1) direction. In the CuSe sheet, Cu1+ is bonded to four equivalent Se2- atoms to form a mixture of corner and edge-sharing CuSe4 tetrahedra. All Cu–Se bond lengths are 2.52 Å. Se2- is bonded in a 4-coordinate geometry to four equivalent Cu1+ atoms. In the LaO sheet, La3+ is bonded in a 4-coordinate geometry to four equivalent O2- atoms. All La–O bond lengths are 2.38 Å. O2- is bonded to four equivalent La3+ atoms to form a mixture of corner and edge-sharing OLa4 tetrahedra.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on LaNO4 by Materials Project

LaONO3 crystallizes in the orthorhombic Pnma space group. The structure is one-dimensional and consists of four nitric acid molecules and two LaO ribbons oriented in the (0, 1, 0) direction. In each LaO ribbon, La3+ is bonded in a 2-coordinate geometry to two equivalent O2- atoms. There are one shorter (2.13 Å) and one longer (2.16 Å) La–O bond lengths. O2- is bonded in a distorted bent 150 degrees geometry to two equivalent La3+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on LaNiPO by Materials Project

LaNiPO is lead oxide-derived structured and crystallizes in the tetragonal P4/nmm space group. The structure is two-dimensional and consists of one LaO sheet oriented in the (0, 0, 1) direction and one NiP sheet oriented in the (0, 0, 1) direction. In the LaO sheet, La3+ is bonded in a 4-coordinate geometry to four equivalent O2- atoms. All La–O bond lengths are 2.38 Å. O2- is bonded to four equivalent La3+ atoms to form a mixture of edge and corner-sharing OLa4 tetrahedra. In the NiP sheet, Ni2+ is bonded to four equivalent P3- atoms to form a mixture of distorted edge and corner-sharing NiP4 trigonal pyramids. All Ni–P bond lengths are 2.24 Å. P3- is bonded in a 4-coordinate geometry to four equivalent Ni2+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on LaNiAsO by Materials Project

LaNiAsO is lead oxide-derived structured and crystallizes in the tetragonal P4/nmm space group. The structure is two-dimensional and consists of one LaO sheet oriented in the (0, 0, 1) direction and one NiAs sheet oriented in the (0, 0, 1) direction. In the LaO sheet, La3+ is bonded in a 4-coordinate geometry to four equivalent O2- atoms. All La–O bond lengths are 2.40 Å. O2- is bonded to four equivalent La3+ atoms to form a mixture of edge and corner-sharing OLa4 tetrahedra. In the NiAs sheet, Ni2+ is bonded to four equivalent As3- atoms to form a mixture of distorted edge and corner-sharing NiAs4 tetrahedra. All Ni–As bond lengths are 2.33 Å. As3- is bonded in a 4-coordinate geometry to four equivalent Ni2+ atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on LaCoAsO by Materials Project

LaOCoAs is Parent of FeAs superconductors structured and crystallizes in the tetragonal P4/nmm space group. The structure is two-dimensional and consists of one CoAs sheet oriented in the (0, 0, 1) direction and one LaO sheet oriented in the (0, 0, 1) direction. In the CoAs sheet, Co2+ is bonded to four equivalent As3- atoms to form a mixture of corner and edge-sharing CoAs4 tetrahedra. All Co–As bond lengths are 2.32 Å. As3- is bonded in a 4-coordinate geometry to four equivalent Co2+ atoms. In the LaO sheet, La3+ is bonded in a 4-coordinate geometry to four equivalent O2- atoms. All La–O bond lengths are 2.39 Å. O2- is bonded to four equivalent La3+ atoms to form a mixture of corner and edge-sharing OLa4 tetrahedra.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on La3Ni4(P2O)2 by Materials Project

La3Ni4P4O2 crystallizes in the tetragonal I4/mmm space group. The structure is two-dimensional and consists of two La(NiP)4 sheets oriented in the (0, 0, 1) direction and two LaO sheets oriented in the (0, 0, 1) direction. In each La(NiP)4 sheet, La3+ is bonded in a distorted body-centered cubic geometry to eight equivalent P3- atoms. All La–P bond lengths are 3.12 Å. Ni+1.75+ is bonded to four P3- atoms to form a mixture of edge and corner-sharing NiP4 tetrahedra. There are two shorter (2.24 Å) and two longer (2.29 Å) Ni–P bond lengths. There are two inequivalent P3- sites. In the first P3- site, P3- is bonded in a 9-coordinate geometry to four equivalent La3+, four equivalent Ni+1.75+, and one P3- atom. The P–P bond length is 2.61 Å. In the second P3- site, P3- is bonded in a 4-coordinate geometry to four equivalent Ni+1.75+ atoms. In each LaO sheet, La3+ is bonded in a 4-coordinate geometry to four equivalent O2- atoms. All La–O bond lengths are 2.36 Å. O2- is bonded to four equivalent La3+ atoms to form a mixture of edge and corner-sharing OLa4 tetrahedra.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on LiLaSO by Materials Project

LiSLaO is Parent of FeAs superconductors structured and crystallizes in the tetragonal P4/nmm space group. The structure is two-dimensional and consists of one LaO sheet oriented in the (0, 0, 1) direction and one LiS sheet oriented in the (0, 0, 1) direction. In the LaO sheet, La3+ is bonded in a 4-coordinate geometry to four equivalent O2- atoms. All La–O bond lengths are 2.36 Å. O2- is bonded to four equivalent La3+ atoms to form a mixture of edge and corner-sharing OLa4 tetrahedra. In the LiS sheet, Li1+ is bonded to four equivalent S2- atoms to form a mixture of edge and corner-sharing LiS4 tetrahedra. All Li–S bond lengths are 2.46 Å. S2- is bonded in a 4-coordinate geometry to four equivalent Li1+ atoms.

36 MATERIALS SCIENCE↗

NASA NTRS2024

Land Cover Change Analysis and Spatial Variations in Southeast Asian Nations: Insights on Spatial Scale Dynamics

Land cover type is a fundamental aspect of studies using remote sensing for environmental analysis such as monitoring deforestation, quantifying wildland fire emissions, and more. There are many land cover products available for varying time periods and spatial resolutions, each with different land cover class definitions and number of land cover classes. These differences yield inherent variation in land cover estimates. In this study, we explore the spatial and areal variation between two major datasets for their commonly available time of 2018 to 2022 (MODIS 500m Land Cover and Esri Sentinel-2 10m land cover) in the continental Southeast Asia countries of Cambodia, Laos, Myanmar, Thailand, and Vietnam. To enable comparison, we resampled the datasets and reclassified the land cover classes to a common scheme. Major disagreement was detected between Esri and MODIS, especially for the wetlands/flooded vegetation class in which only 3.6% of pixels were in agreement. In addition to quantifying variation between the datasets, we quantify land cover change at the decadal scale of 2001, 2011, and 2021 for each country and identified province-level hotspots of land cover change. Cambodia experienced the highest rate of land cover change with 67.8% of total land area changed, followed by Vietnam (58.6%), Laos (50.2%), Myanmar (46.9%), and Thailand (46.3%). The highest rate of land cover change was detected in Odtar Mean Chey, Cambodia, which had large swaths of forest area cleared for agricultural production, river damming, and more. Ultimately, many areas in the region experienced forest clearing for crop production (i.e. rice) which appeared to be classified as wetland in the MODIS product, and crop in the Esri product. Myanmar was the only country which did not experience net decline in forest area over the 2001 to 2021 time period.

Land Cover Change↗

DOE OSTI2024

Influence of Joule Heating on the Stability of High Temperature Irradiation Resistant Thermocouples

Development of in-core instrumentation is driven by the pursuit of safer and more economic energy production from both existing nuclear reactors and Generation IV reactor designs. Idaho National Laboratory (INL) has developed high temperature irradiation resistant thermocouples (HTIR-TCs) for temperature sensing inside Generation IV nuclear reactors. These thermocouples are composed of phosphorus-doped niobium (Nb-P) and lanthana-doped molybdenum (Mo-LaO) thermoelements, an alumina (Al2O3) insulation, and a niobium sheath. HTIR-TCs require an initial heat treatment exceeding the maximum service temperature to stabilize the generated electromotive force (EMF) signal; however, the mechanism behind this stabilization is not well understood. This work evaluates the impact of Joule heating on the thermoelements' microstructures, chemical stability, and mechanical properties to determine the mechanisms by which the EMF signal stabilization occurs. Accordingly, during the Joule heat treatment, a secondary Nb3P phase coarsened along the length of the Nb-P thermoelement, along with the formation of an interaction region at the Al2O3/niobium interface. The interaction between the alumina insulation and the Nb-P thermoelement was also observed within the Mo-LaO thermoelement. Joule heating induced stability within the generated EMF signal of HTIR-TCs through the formation of secondary phases within the Nb-P and the interaction of the alumina insulation with the thermoelements.

46 - INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AN↗

DOE OSTI2024

Influence of Joule Heating on the Stability of High Temperature Irradiation-resistant Thermocouples

Development of in-core instrumentation is driven by the pursuit of safer, more economic energy production from the perspective of both existing nuclear reactors and Generation IV reactor designs. Idaho National Laboratory has developed high-temperature irradiation-resistant thermocouples (HTIR-TCs) for temperature sensing inside Generation IV nuclear reactors. These thermocouples are composed of phosphorus-doped niobium (Nb-P) and lanthana-doped molybdenum (Mo-LaO) thermoelements, an alumina (Al2O3) insulation, and a niobium sheath. HTIR-TCs require an initial heat treatment exceeding the maximum service temperature to stabilize the generated electromotive force (EMF) signal. The mechanism behind the stabilization of the HTIR-TCs through traditional heat treatment methods is understood; however, the traditional heat treatment method is expensive, time consuming, and results in a heterogeneous microstructure. Therefore, we investigated a rapid method for stabilization and microstructure homogeneity, through Joule heating. This work evaluates the impact of Joule heating on the thermoelements’ microstructures, chemical stability, and mechanical properties so as to determine the mechanisms by which stabilization of the EMF signal occurs. Accordingly, during the Joule heat treatment, a secondary Nb3P phase coarsened along the length of the Nb-P thermoelement, along with the formation of an interaction region at the Al2O3/niobium interface. The interaction between the alumina insulation and the Nb-P thermoelement was also observed within the Mo-LaO thermoelement. Joule heating induced stability within the generated HTIR-TC EMF signal via the formation of secondary phases within the Nb-P and the interaction between the alumina insulation and the thermoelements.

46 - INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AN↗