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At least 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Topographic Correction of Optical Remote Sensing Images in Mountainous Areas: A systematic review

Rugged terrain distorts optical remote sensing observations and subsequently impacts land cover classification and biophysical and biochemical parameter retrieval over mountainous areas. Therefore, topographic correction (TC) is a prerequisite for many remote sensing applications. Although various TC methods have been explored over the past four decades to mitigate topographic effects, a systematic and global review of these studies is still lacking. Using a multicomponent bibliometric approach, we extracted bibliometric metadata from 426 publications identified by searching titles, keywords, and abstracts for research on “topographic correction” and “topographic effects” in Scopus and Web of Science (WoS) from 1980 to 2022. Here this systematic review revealed a rapid growth in the number of TC studies since the 1980s, primarily driven by the availability of decametric-resolution remote sensing observations and digital elevation models (DEMs). Most of the research has focused on relatively low-elevation regions, with increasing attention beyond American and European regions, particularly in China. The seasonal distribution of satellite acquisition for TC showed considerable imbalance, mainly concentrated in months with favorable solar illumination conditions (e.g., May to October). Important themes emerged from the keyword analysis, including satellite sensors, DEMs, TC methods, evaluation criteria, and applications.

58 GEOSCIENCES↗
DOE OSTI2023

An Extratropical Pathway for the Madden–Julian Oscillation’s Influence on North Atlantic Tropical Cyclones

Abstract This study investigates the combined impacts of the Madden–Julian oscillation (MJO) and extratropical anticyclonic Rossby wave breaking (AWB) on subseasonal Atlantic tropical cyclone (TC) activity and their physical connections. Our results show that during MJO phases 2–3 (enhanced Indian Ocean convection) and 6–7 (enhanced tropical Pacific convection), there are significant changes in basinwide TC activity. The MJO and AWB collaborate to suppress basinwide TC activity during phases 6–7 but not during phases 2–3. During phases 6–7, when AWB occurs, various TC metrics including hurricanes, accumulated cyclone energy, and rapid intensification probability decrease by ∼50%–80%. Simultaneously, large-scale environmental variables, like vertical wind shear, precipitable water, and sea surface temperatures become extremely unfavorable for TC formation and intensification, compared to periods characterized by suppressed AWB activity during the same MJO phases. Further investigation reveals that AWB events during phases 6–7 occur in concert with the development of a stronger anticyclone in the lower troposphere, which transports more dry, stable extratropical air equatorward, and drives enhanced tropical SST cooling. As a result, individual AWB events in phases 6–7 can disturb the development of surrounding TCs to a greater extent than their phases 2–3 counterparts. The influence of the MJO on AWB over the western subtropical Atlantic can be attributed to the modulation of the convectively forced Rossby wave source over the tropical eastern Pacific. A significant number of Rossby waves initiating from this region during phases 5–6 propagate into the subtropical North Atlantic, preceding the occurrence of AWB events in phases 6–7.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Are North Atlantic Tropical Cyclones Modulated by the Madden–Julian Oscillation in HighResMIP AGCMs?

This study assesses the representation of the observed relationship between Atlantic tropical cyclones (TCs) and the Madden–Julian oscillation (MJO) across nine models participating in CMIP6 High Resolution Model Intercomparison Project (HighResMIP). Most models struggle to faithfully reproduce the observed impacts of the MJO on Atlantic TCs, with the primary issue being the underestimated TC activity over the Atlantic main development region (MDR). The negative biases in genesis frequency within the MDR can be further attributed to weaker-than-observed African easterly wave (AEW) activity south of ∼12°N. Errors in the diabatic heating profile within the Atlantic intertropical convergence zone lead to insufficient potential vorticity production in the lower troposphere and constrain the amplification of AEWs. In addition to the biased TC climatology, the eastward-propagating power of the MJO is consistently underestimated across all models. Nevertheless, in models with a higher eastward–westward power ratio, the simulated MJO demonstrates a stronger capacity to modulate subseasonal TC activity. Models with relatively realistic eastward propagation of the MJO also exhibit greater variance in tropical intraseasonal convection. Stronger contrasts in convective heating over the North Atlantic between phases 2–3 and phases 6–7 drive larger fluctuations in MDR shear and AEW activity over the Gulf of Mexico and West Africa, resulting in a more pronounced TC response to the MJO. Overall, our findings suggest that improved MDR TC climatology and MJO propagation are essential for models to accurately capture the observed modulations of Atlantic TCs by the MJO.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Effects of Atmosphere and Ocean Horizontal Model Resolution on Tropical Cyclone and Upper-Ocean Response Forecasts in Four Major Hurricanes

A coupled atmosphere–ocean model is necessary for tropical cyclone (TC) prediction to accurately characterize ocean feedback on atmospheric processes within the TC environment. Here, the ECMWF coupled global model is run at horizontal resolutions from 9 to 1.4 km in the atmosphere, as well as 25 and 8 km in the ocean, to identify how resolution impacts forecast accuracy of four observed major TCs in the Atlantic: Irma, Florence, Teddy, and Ida. Most of the resolutions used here are unprecedented for global models. GOES-16 and synthetic aperture radar (SAR) satellite images and best track data are used for atmospheric validation. Salinity and temperature observations from Air-Launched Autonomous Micro-Observer (ALAMO) floats are used to validate modeled upper-ocean response, including mixed layer deepening, sea surface cooling, and near-inertial waves in the wakes of TCs. Increasing atmospheric resolution leads to more realistic TC structure and stronger winds, significantly improving TC intensity forecasts and modestly improving track errors. Ocean resolution impacts the upper-ocean response but does not influence atmospheric forecasts for the fast-moving TCs considered here. Stronger mixing, sea surface cooling, and near-inertial oscillations are found for both higher atmosphere and ocean resolutions, provided the initial upper-ocean state is the same for the two ocean resolutions. Whether this agrees better with the ALAMO observations also depends on the realism of the initial upper-ocean state in the model, emphasizing the importance of ocean initialization for the accurate upper-ocean response. Overall, the model at all resolutions correctly predicts stronger mixing, surface cooling, and near-inertial oscillation amplitudes to the right of a TC center, as observed by ALAMO floats.

Atmosphere-ocean interaction↗
DOE OSTI2023

Intensification of Hurricane Sally (2020) over the Mississippi River Plume

Abstract Tropical Cyclone (TC) Sally formed on 11 September 2020, traveled through the Gulf of Mexico (GMX), and intensified rapidly before making landfall on the Alabama coast as a devastating category-2 TC with extensive coastal and inland flooding. In this study, using a combination of observations and idealized numerical model experiments, we demonstrate that the Mississippi River plume played a key role in the intensification of Sally near the northern Gulf Coast. As the storm intensified and its translation slowed before landfall, sea surface cooling was reduced along its track, coincident with a pronounced increase in SSS. Further analysis reveals that TC Sally encountered a warm Loop Current eddy in the northern GMX close to the Mississippi River plume. Besides deepening the thermocline, the eddy advected low-salinity Mississippi River plume water into the storm’s path. This resulted in the development of strong upper-ocean salinity stratification, with a shallow layer of freshwater lying above a deep, warm “barrier layer.” Consequently, TC-induced mixing and the associated sea surface cooling were reduced, aiding Sally’s intensification. These results suggest that the Mississippi River plume and freshwater advection by the Loop Current eddies can play an important role in TC intensification near the U.S. Gulf Coast.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Vitrification of Hanford Tank 241-AP-107 with Recycled Condensate

During the vitrification of nuclear waste at the Hanford Waste Treatment and Immobilization Plant (WTP) – the primary mission of the U.S. Department of Energy Office of River Protection – the offgas condensate generated from the waste-to-glass conversion is currently planned to be concentrated by evaporation in the Effluent Management Facility (EMF). This concentrated condensate can then be recycled back to the incoming waste and vitrified. To test the recycle process, a test apparatus was designed to mimic the EMF evaporator and used to concentrate a volume of condensate that had been previously produced during the vitrification of Hanford tank 241-AP-107 (referred to herein as AP-107) waste in a continuous laboratory-scale melter (CLSM). The test apparatus successfully concentrated the AP-107 condensate by a factor of 10 while retaining over 90 % of the technetium-99 ( 99 Tc), Cs, and I inventory. A second portion of AP-107 waste was retrieved by Washington River Protection Solutions, LLC, given to Pacific Northwest National Laboratory, and combined with the AP-107 condensate concentrate after undergoing solids filtration and cesium removal by ion exchange. This combination served to approximate the recycling action to be performed at the WTP. After the addition of glass-forming chemicals (GFCs), the combined AP-107 waste and AP-107 condensate concentrate were processed in the CLSM to produce a glass, called AP-107-1R, that was designed to satisfy the WTP baseline requirements (Kim et al. 2012). During the 8.87 hours of processing, 7.27 kg of AP-107-1R glass were produced for an average glass production rate of 1739 kg m 2 d -1 . Compared to the previous run in the CLSM without recycled condensate, the run with the recycle had a greater average glass production rate, but the rate was within the potential range of variability when processing melter feeds with similar composition in the CLSM. The glass produced from the AP-107 recycle run in the CLSM was within 10 % of the target AP-107-1R glass composition with respect to the primary glass components. Analysis of the minor component impurities revealed that their content in the glass product had approached their nominal target after 2 turnovers of the glass inventory in the CLSM while the activity of the minor radionuclides was retained in the glass product. The 99 Tc and total cesium content in the combined AP-107 waste and recycled condensate were maintained at concentrations expected to be experienced at the WTP. During processing in the CLSM, at discrete sampling time periods, the target 99 Tc/Cs mass ratio in the glass formulation varied from 0.9 to 62.9. Across this range, the Cs retention in the glass ranged from 53 to 60 %, while the retention from the entire runtime totaled 68 %, values which align with Cs retention in other scaled melter systems while processing LAW melter feeds at 99 Tc/Cs mass ratios ranging from 1 to 100. The 99 Tc retention in the glass ranged from 22 to 32 %, primarily due to the cold-cap coverage on the glass melt surface, the area covered by reacting melter feed, varying from ~80 % to ~95 % during processing, demonstrating greater volatility of 99 Tc from the glass while more surface was exposed, as expected based on previous 99 Tc volatility studies.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2021

Vitrification of Hanford Tank Wastes for Condensate Recycle and Feed Composition Changeover Testing

During the vitrification of Hanford Site nuclear waste at the Waste Treatment and Immobilization Plant (WTP), which is a part of the safe and efficient retrieval, treatment, and disposal mission of the U.S. Department of Energy Office of River Protection, the offgas condensate generated from the waste-to-glass conversion is currently planned to be concentrated by evaporation in the Effluent Management Facility (EMF). This concentrated condensate can then be recycled back to the incoming waste and vitrified. To test the recycle process, an apparatus was designed and built to mimic the EMF evaporator and was then used to concentrate a volume of condensate produced during the vitrification of a sample of Hanford tank 241-AP-107 (referred to herein as AP-107) waste in a continuous laboratory-scale melter (CLSM). The concentrated condensate was added to an additional sample of AP-107 waste, to mimic one round of the recycle process, and the combined solution was vitrified, producing a second round of recycle condensate. In the current study, the EMF test apparatus was used to concentrate the second-round recycle condensate under evaporation conditions (at 45 °C and 1.4 psia) designed to emulate EMF operation. The condensate was successfully concentrated by a factor of ~10 while retaining over 95 % of the technetium-99 ( 99 Tc), Cs, and I inventories in the concentrate. Another portion of AP-107 waste was retrieved by Washington River Protection Solutions, LLC (WRPS) and transferred to Pacific Northwest National Laboratory (PNNL), where it was pretreated and then combined with the second-round recycle AP-107 condensate concentrate and glass-forming chemicals (GFCs) to form the two-time recycle AP-107 melter feed, approximating a second round to the recycling action to be performed at the WTP. A portion of AP-105 waste was also retrieved by WRPS and provided to PNNL for pretreatment and combining with GFCs to form AP-105 melter feed. The two-time recycle AP-107 and AP-105 melter feeds were processed consecutively in the CLSM. The CLSM run proceeded for 13.63 hours, producing 9.70 kg of glass for an average glass production rate of 1464 kg m 2 d -1 during the two-time recycle AP-107 feed charging and 1568 kg m 2 d -1 during the AP-105 feed charging. The rate during AP-107 charging was essentially equivalent to the rate when processing no-recycle AP-107 feed and lower than that achieved when processing one-time recycle AP-107 feed. However, all rates were within the potential range of variability when processing melter feeds with similar composition in the CLSM. Likewise, the rate during AP-105 charging was higher than the previous rate processing AP-105, but within the potential CLSM range. The cold-cap characteristics changed from the typically thin AP-107 cold cap to a foamy-edged cold cap as previously seen with AP-105 shortly after transitioning to the AP-105 melter feed. The glass produced during the CLSM run was within 10 % of its target composition for the primary glass components. The CaO and Li 2 O targets varied by more than 1 wt% between the two-time recycle AP-107 and AP-105 glass targets and it took about 2 turnovers of the CLSM glass inventory to reach a relative chemical steady state in the glass for CaO and Li 2 O after the melter feed inputs were switched. The 99 Tc and total cesium content in the melter feeds were maintained at concentrations expected to be experienced at the WTP. During the CLSM run, while processing the two-time recycle AP-107 melter feed at a relative chemical steady state, the 99 Tc/Cs ratio was 10, and 34% of 99 Tc and 74% of Cs were retained in the glass. These values were higher than those measured in the CLSM run with one-time recycle AP-107 melter feed. After the transition to processing the AP-105 melter feed, when the production reached a relative chemical steady state, the 99 Tc/Cs ratio was 77 while 44% of 99 Tc was retained in the glass. The C's retention during this time frame reached 200% due to the excess C's in the glass after the target content decreased to 15% of its initial level in the two-time recycle AP-107 melter feed to the lower target in the Ap-105 melter feed. While iodine was below inductively coupled plasma mass spectrometry analytical reporting limits in the melter feed and glass samples, it was detected in quantities above the analytical reporting limits in the liquid and filter samples collected from the CLSM offgas treatment system. The behavior of iodine in the CLSM offgas treatment system followed a similar pattern to those of 99 Tc and Cs.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2023

High-temperature irradiation-resistant thermocouple instability model for in-pile reactor use

This article presents an instability model for the high-temperature irradiation-resistant thermocouple (HTIR-TC). Here the term instability defines the superposition of both drift and inhomogeneity of TC thermoelements occurring simultaneously. The HTIR-TC is an advanced thermocouple (TC) that uses the refractory metals niobium and molybdenum as sensing thermoelements for generating electromotive force (EMF) in a field of neutrons and at temperatures upward of 1,600°C. In the Advanced Gas Reactor (AGR) 5/6/7 tests conducted at Idaho National Laboratory’s Advanced Test Reactor (ATR), the HTIR-TCs showed low to moderate instability throughout the life of the test. The instability model reveals that HTIR-TCs can, when the operating temperature of the reactor fuel is normal, maintain performance throughout an 18-month refueling cycle typical of nuclear power plants, reflecting an instability of less than ±1%. The HTIR-TC is also qualified for incorporation into a test fixture during the testing of new fuels.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Bioconversion of Thermochemical Intermediates

Thermochemical (TC) biofuels production via both pyrolysis and hydrothermal liquefaction produces aqueous waste streams, typically with organic compounds at concentrations of -50-100 g/L. These streams represent a wastewater treatment cost and carbon loss for the TC biorefinery, but the concentration range for these compounds is ideal for bioconversion. To that end, the Bioconversion of Thermochemical Intermediates (BTI) project is developing advanced analytics and engineered microbes to convert these waste streams to co-products, with the overall aim of improving the economics and carbon conversion efficiency of TC biorefining. To date, we have primarily focused on development of advanced analytical chemistry approaches to fully characterize TC aqueous streams and engineering of Pseudomonas putida for conversion of non-conventional substrates, including methylated phenolics, cyclic ketones, furans, and C1-C3 light oxygenates, into atom-efficient products. Two primary challenges are the rapid deployment of aqueous-compatible analytics to changing upstream conditions and dealing with the toxicity of the feed streams to engineered microbes. The project efforts have resulted in engineered strains of P. putida able to consume 90% of the organic compounds in aqueous waste streams from catalytic fast pyrolysis, more than 300-fold toxicity tolerance improvements in P. putida, and carbon closures exceeding 90% for TC wastewater streams across multiple processing technologies.

BASIC BIOLOGICAL SCIENCES,BIOMASS FUELS↗
DOE OSTI2020

Materials Data on KTcCl3 by Materials Project

KTcCl3 crystallizes in the monoclinic Cc space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 8-coordinate geometry to eight Cl1- atoms. There are a spread of K–Cl bond distances ranging from 3.12–3.70 Å. In the second K1+ site, K1+ is bonded in a 6-coordinate geometry to eight Cl1- atoms. There are a spread of K–Cl bond distances ranging from 3.15–3.87 Å. There are two inequivalent Tc2+ sites. In the first Tc2+ site, Tc2+ is bonded in a 4-coordinate geometry to one Tc2+ and four Cl1- atoms. The Tc–Tc bond length is 2.10 Å. There are a spread of Tc–Cl bond distances ranging from 2.40–2.45 Å. In the second Tc2+ site, Tc2+ is bonded in a 4-coordinate geometry to one Tc2+ and four Cl1- atoms. There are a spread of Tc–Cl bond distances ranging from 2.40–2.44 Å. There are six inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 3-coordinate geometry to two K1+ and one Tc2+ atom. In the second Cl1- site, Cl1- is bonded in a 3-coordinate geometry to two K1+ and one Tc2+ atom. In the third Cl1- site, Cl1- is bonded in a 1-coordinate geometry to four K1+ and one Tc2+ atom. In the fourth Cl1- site, Cl1- is bonded in a 3-coordinate geometry to two K1+ and two Tc2+ atoms. In the fifth Cl1- site, Cl1- is bonded in a 2-coordinate geometry to two K1+ and two Tc2+ atoms. In the sixth Cl1- site, Cl1- is bonded in a 1-coordinate geometry to four K1+ and one Tc2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tc2O5F4 by Materials Project

TcO3FTcO2F3 crystallizes in the monoclinic P2_1/c space group. The structure is one-dimensional and consists of four TcO3F clusters and two TcO2F3 ribbons oriented in the (1, 0, 0) direction. In each TcO3F cluster, Tc7+ is bonded in a tetrahedral geometry to three O2- and one F1- atom. There is two shorter (1.70 Å) and one longer (1.71 Å) Tc–O bond length. The Tc–F bond length is 1.87 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one Tc7+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one Tc7+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one Tc7+ atom. F1- is bonded in a single-bond geometry to one Tc7+ atom. In each TcO2F3 ribbon, Tc7+ is bonded to two O2- and four F1- atoms to form distorted corner-sharing TcO2F4 octahedra. The corner-sharing octahedral tilt angles are 23°. Both Tc–O bond lengths are 1.69 Å. There are a spread of Tc–F bond distances ranging from 1.87–2.15 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one Tc7+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one Tc7+ atom. There are three inequivalent F1- sites. In the first F1- site, F1- is bonded in a bent 150 degrees geometry to two equivalent Tc7+ atoms. In the second F1- site, F1- is bonded in a single-bond geometry to one Tc7+ atom. In the third F1- site, F1- is bonded in a single-bond geometry to one Tc7+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KFeTc2 by Materials Project

KTc2Fe crystallizes in the cubic F-43m space group. The structure is three-dimensional. K1+ is bonded in a distorted body-centered cubic geometry to ten Tc2- and four equivalent Fe3+ atoms. There are four shorter (2.74 Å) and six longer (3.16 Å) K–Tc bond lengths. All K–Fe bond lengths are 2.74 Å. There are two inequivalent Tc2- sites. In the first Tc2- site, Tc2- is bonded to four equivalent K1+ and four equivalent Tc2- atoms to form distorted edge-sharing TcK4Tc4 tetrahedra. All Tc–Tc bond lengths are 2.74 Å. In the second Tc2- site, Tc2- is bonded in a 4-coordinate geometry to six equivalent K1+, four equivalent Tc2-, and four equivalent Fe3+ atoms. All Tc–Fe bond lengths are 2.74 Å. Fe3+ is bonded in a distorted body-centered cubic geometry to four equivalent K1+ and four equivalent Tc2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BaSiTc2 by Materials Project

BaTc2Si crystallizes in the cubic F-43m space group. The structure is three-dimensional. Ba2+ is bonded to ten Tc3- atoms to form distorted BaTc10 tetrahedra that share corners with six equivalent BaTc10 tetrahedra, corners with twelve equivalent TcBa4Tc4 tetrahedra, faces with four equivalent TcBa4Tc4 tetrahedra, and faces with twelve equivalent BaTc10 tetrahedra. There are four shorter (2.94 Å) and six longer (3.39 Å) Ba–Tc bond lengths. There are two inequivalent Tc3- sites. In the first Tc3- site, Tc3- is bonded in a 8-coordinate geometry to six equivalent Ba2+, four equivalent Tc3-, and four equivalent Si4+ atoms. All Tc–Tc bond lengths are 2.94 Å. All Tc–Si bond lengths are 2.94 Å. In the second Tc3- site, Tc3- is bonded to four equivalent Ba2+ and four equivalent Tc3- atoms to form distorted TcBa4Tc4 tetrahedra that share corners with twelve equivalent BaTc10 tetrahedra, edges with twelve equivalent TcBa4Tc4 tetrahedra, and faces with four equivalent BaTc10 tetrahedra. Si4+ is bonded in a 4-coordinate geometry to four equivalent Tc3- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb5Tc3S7 by Materials Project

Rb5Tc3S7 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are seven inequivalent Rb1+ sites. In the first Rb1+ site, Rb1+ is bonded to six S2- atoms to form RbS6 octahedra that share corners with six TcS5 square pyramids. There are a spread of Rb–S bond distances ranging from 3.10–3.42 Å. In the second Rb1+ site, Rb1+ is bonded in a 6-coordinate geometry to six S2- atoms. There are a spread of Rb–S bond distances ranging from 3.19–3.66 Å. In the third Rb1+ site, Rb1+ is bonded in a 2-coordinate geometry to six S2- atoms. There are a spread of Rb–S bond distances ranging from 3.12–3.61 Å. In the fourth Rb1+ site, Rb1+ is bonded in a 3-coordinate geometry to four S2- atoms. There are a spread of Rb–S bond distances ranging from 3.18–3.78 Å. In the fifth Rb1+ site, Rb1+ is bonded in a 4-coordinate geometry to four S2- atoms. There are a spread of Rb–S bond distances ranging from 3.18–3.45 Å. In the sixth Rb1+ site, Rb1+ is bonded in a 6-coordinate geometry to six S2- atoms. There are a spread of Rb–S bond distances ranging from 3.25–3.76 Å. In the seventh Rb1+ site, Rb1+ is bonded in a 5-coordinate geometry to five S2- atoms. There are a spread of Rb–S bond distances ranging from 3.20–3.77 Å. There are four inequivalent Tc3+ sites. In the first Tc3+ site, Tc3+ is bonded to five S2- atoms to form TcS5 square pyramids that share a cornercorner with one RbS6 octahedra and edges with four TcS5 square pyramids. The corner-sharing octahedral tilt angles are 7°. There are a spread of Tc–S bond distances ranging from 2.42–2.44 Å. In the second Tc3+ site, Tc3+ is bonded to five S2- atoms to form TcS5 square pyramids that share a cornercorner with one RbS6 octahedra and edges with four TcS5 square pyramids. The corner-sharing octahedral tilt angles are 1°. There are a spread of Tc–S bond distances ranging from 2.42–2.44 Å. In the third Tc3+ site, Tc3+ is bonded to five S2- atoms to form TcS5 square pyramids that share a cornercorner with one RbS6 octahedra and edges with four TcS5 square pyramids. The corner-sharing octahedral tilt angles are 11°. There are a spread of Tc–S bond distances ranging from 2.42–2.46 Å. In the fourth Tc3+ site, Tc3+ is bonded to five S2- atoms to form TcS5 square pyramids that share a cornercorner with one RbS6 octahedra and edges with four TcS5 square pyramids. The corner-sharing octahedral tilt angles are 5°. There are a spread of Tc–S bond distances ranging from 2.40–2.48 Å. There are ten inequivalent S2- sites. In the first S2- site, S2- is bonded in an octahedral geometry to five Rb1+ and one Tc3+ atom. In the second S2- site, S2- is bonded in a 5-coordinate geometry to four Rb1+ and one Tc3+ atom. In the third S2- site, S2- is bonded in a 7-coordinate geometry to four Rb1+ and three Tc3+ atoms. In the fourth S2- site, S2- is bonded in a 8-coordinate geometry to three Rb1+ and three Tc3+ atoms. In the fifth S2- site, S2- is bonded in a 6-coordinate geometry to three Rb1+ and three Tc3+ atoms. In the sixth S2- site, S2- is bonded in a 6-coordinate geometry to five Rb1+ and one Tc3+ atom. In the seventh S2- site, S2- is bonded in a 7-coordinate geometry to four Rb1+ and three Tc3+ atoms. In the eighth S2- site, S2- is bonded in a 6-coordinate geometry to three Rb1+ and three Tc3+ atoms. In the ninth S2- site, S2- is bonded in a 6-coordinate geometry to three Rb1+ and three Tc3+ atoms. In the tenth S2- site, S2- is bonded in a 6-coordinate geometry to five Rb1+ and one Tc3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al3Tc by Materials Project

TcAl3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Tc is bonded to twelve Al atoms to form TcAl12 cuboctahedra that share corners with four equivalent TcAl12 cuboctahedra, corners with eight equivalent AlAl8Tc4 cuboctahedra, edges with eight equivalent TcAl12 cuboctahedra, edges with sixteen equivalent AlAl8Tc4 cuboctahedra, faces with four equivalent TcAl12 cuboctahedra, and faces with fourteen AlAl8Tc4 cuboctahedra. There are four shorter (2.71 Å) and eight longer (2.78 Å) Tc–Al bond lengths. There are two inequivalent Al sites. In the first Al site, Al is bonded to four equivalent Tc and eight Al atoms to form AlAl8Tc4 cuboctahedra that share corners with twelve equivalent AlAl8Tc4 cuboctahedra, edges with eight equivalent TcAl12 cuboctahedra, edges with sixteen AlAl8Tc4 cuboctahedra, faces with four equivalent TcAl12 cuboctahedra, and faces with fourteen AlAl8Tc4 cuboctahedra. There are four shorter (2.71 Å) and four longer (2.78 Å) Al–Al bond lengths. In the second Al site, Al is bonded to four equivalent Tc and eight equivalent Al atoms to form distorted AlAl8Tc4 cuboctahedra that share corners with four equivalent AlAl8Tc4 cuboctahedra, corners with eight equivalent TcAl12 cuboctahedra, edges with twenty-four AlAl8Tc4 cuboctahedra, faces with six equivalent TcAl12 cuboctahedra, and faces with twelve AlAl8Tc4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TcGe3 by Materials Project

TcGe3 is alpha bismuth trifluoride structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Tc is bonded to twelve Ge atoms to form TcGe12 cuboctahedra that share corners with four equivalent TcGe12 cuboctahedra, corners with eight equivalent GeTc4Ge8 cuboctahedra, edges with eight equivalent TcGe12 cuboctahedra, edges with sixteen equivalent GeTc4Ge8 cuboctahedra, faces with four equivalent TcGe12 cuboctahedra, and faces with fourteen GeTc4Ge8 cuboctahedra. There are eight shorter (2.80 Å) and four longer (2.88 Å) Tc–Ge bond lengths. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded to four equivalent Tc and eight Ge atoms to form GeTc4Ge8 cuboctahedra that share corners with twelve equivalent GeTc4Ge8 cuboctahedra, edges with eight equivalent TcGe12 cuboctahedra, edges with sixteen GeTc4Ge8 cuboctahedra, faces with four equivalent TcGe12 cuboctahedra, and faces with fourteen GeTc4Ge8 cuboctahedra. There are four shorter (2.80 Å) and four longer (2.88 Å) Ge–Ge bond lengths. In the second Ge site, Ge is bonded to four equivalent Tc and eight equivalent Ge atoms to form GeTc4Ge8 cuboctahedra that share corners with four equivalent GeTc4Ge8 cuboctahedra, corners with eight equivalent TcGe12 cuboctahedra, edges with twenty-four GeTc4Ge8 cuboctahedra, faces with six equivalent TcGe12 cuboctahedra, and faces with twelve GeTc4Ge8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on InTc3 by Materials Project

Tc3In is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Tc1- sites. In the first Tc1- site, Tc1- is bonded to eight Tc1- and four equivalent In3+ atoms to form TcIn4Tc8 cuboctahedra that share corners with twelve equivalent TcIn4Tc8 cuboctahedra, edges with eight equivalent InTc12 cuboctahedra, edges with sixteen TcIn4Tc8 cuboctahedra, faces with four equivalent InTc12 cuboctahedra, and faces with fourteen TcIn4Tc8 cuboctahedra. There are four shorter (2.74 Å) and four longer (2.87 Å) Tc–Tc bond lengths. All Tc–In bond lengths are 2.87 Å. In the second Tc1- site, Tc1- is bonded to eight equivalent Tc1- and four equivalent In3+ atoms to form distorted TcIn4Tc8 cuboctahedra that share corners with four equivalent TcIn4Tc8 cuboctahedra, corners with eight equivalent InTc12 cuboctahedra, edges with twenty-four TcIn4Tc8 cuboctahedra, faces with six equivalent InTc12 cuboctahedra, and faces with twelve TcIn4Tc8 cuboctahedra. All Tc–In bond lengths are 2.74 Å. In3+ is bonded to twelve Tc1- atoms to form InTc12 cuboctahedra that share corners with four equivalent InTc12 cuboctahedra, corners with eight equivalent TcIn4Tc8 cuboctahedra, edges with eight equivalent InTc12 cuboctahedra, edges with sixteen equivalent TcIn4Tc8 cuboctahedra, faces with four equivalent InTc12 cuboctahedra, and faces with fourteen TcIn4Tc8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ga3Tc by Materials Project

TcGa3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Tc is bonded to twelve Ga atoms to form TcGa12 cuboctahedra that share corners with four equivalent TcGa12 cuboctahedra, corners with eight equivalent GaGa8Tc4 cuboctahedra, edges with eight equivalent TcGa12 cuboctahedra, edges with sixteen equivalent GaGa8Tc4 cuboctahedra, faces with four equivalent TcGa12 cuboctahedra, and faces with fourteen GaGa8Tc4 cuboctahedra. There are four shorter (2.72 Å) and eight longer (2.80 Å) Tc–Ga bond lengths. There are two inequivalent Ga sites. In the first Ga site, Ga is bonded to four equivalent Tc and eight Ga atoms to form GaGa8Tc4 cuboctahedra that share corners with twelve equivalent GaGa8Tc4 cuboctahedra, edges with eight equivalent TcGa12 cuboctahedra, edges with sixteen GaGa8Tc4 cuboctahedra, faces with four equivalent TcGa12 cuboctahedra, and faces with fourteen GaGa8Tc4 cuboctahedra. There are four shorter (2.72 Å) and four longer (2.80 Å) Ga–Ga bond lengths. In the second Ga site, Ga is bonded to four equivalent Tc and eight equivalent Ga atoms to form GaGa8Tc4 cuboctahedra that share corners with four equivalent GaGa8Tc4 cuboctahedra, corners with eight equivalent TcGa12 cuboctahedra, edges with twenty-four GaGa8Tc4 cuboctahedra, faces with six equivalent TcGa12 cuboctahedra, and faces with twelve GaGa8Tc4 cuboctahedra.

36 MATERIALS SCIENCE↗