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At least 667 records · Page 37
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Li2Sm2Ge3 by Materials Project

Li2Sm2Ge3 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Li is bonded to three equivalent Sm and four Ge atoms to form a mixture of distorted corner, edge, and face-sharing LiSm3Ge4 tetrahedra. There are one shorter (3.11 Å) and two longer (3.15 Å) Li–Sm bond lengths. There are a spread of Li–Ge bond distances ranging from 2.56–2.72 Å. There are two inequivalent Sm sites. In the first Sm site, Sm is bonded in a 5-coordinate geometry to nine Ge atoms. There are a spread of Sm–Ge bond distances ranging from 3.11–3.31 Å. In the second Sm site, Sm is bonded in a 12-coordinate geometry to six equivalent Li and six Ge atoms. There are four shorter (3.09 Å) and two longer (3.17 Å) Sm–Ge bond lengths. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 1-coordinate geometry to one Li, six Sm, and two equivalent Ge atoms. There are one shorter (2.50 Å) and one longer (2.53 Å) Ge–Ge bond lengths. In the second Ge site, Ge is bonded in a 6-coordinate geometry to six equivalent Li and three Sm atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KSm3 by Materials Project

KSm3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. K is bonded to twelve Sm atoms to form KSm12 cuboctahedra that share corners with four equivalent KSm12 cuboctahedra, corners with eight equivalent SmK4Sm8 cuboctahedra, edges with eight equivalent KSm12 cuboctahedra, edges with sixteen equivalent SmK4Sm8 cuboctahedra, faces with four equivalent KSm12 cuboctahedra, and faces with fourteen SmK4Sm8 cuboctahedra. There are four shorter (3.74 Å) and eight longer (3.80 Å) K–Sm bond lengths. There are two inequivalent Sm sites. In the first Sm site, Sm is bonded to four equivalent K and eight Sm atoms to form SmK4Sm8 cuboctahedra that share corners with twelve equivalent SmK4Sm8 cuboctahedra, edges with eight equivalent KSm12 cuboctahedra, edges with sixteen SmK4Sm8 cuboctahedra, faces with four equivalent KSm12 cuboctahedra, and faces with fourteen SmK4Sm8 cuboctahedra. There are four shorter (3.74 Å) and four longer (3.80 Å) Sm–Sm bond lengths. In the second Sm site, Sm is bonded to four equivalent K and eight equivalent Sm atoms to form distorted SmK4Sm8 cuboctahedra that share corners with four equivalent SmK4Sm8 cuboctahedra, corners with eight equivalent KSm12 cuboctahedra, edges with twenty-four SmK4Sm8 cuboctahedra, faces with six equivalent KSm12 cuboctahedra, and faces with twelve SmK4Sm8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm2Ni17 by Materials Project

Sm2Ni17 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Sm sites. In the first Sm site, Sm is bonded in a 12-coordinate geometry to eighteen Ni atoms. There are a spread of Sm–Ni bond distances ranging from 2.92–3.21 Å. In the second Sm site, Sm is bonded in a 2-coordinate geometry to twenty Ni atoms. There are a spread of Sm–Ni bond distances ranging from 2.85–3.13 Å. There are four inequivalent Ni sites. In the first Ni site, Ni is bonded in a 2-coordinate geometry to one Sm and thirteen Ni atoms. There are a spread of Ni–Ni bond distances ranging from 2.35–2.71 Å. In the second Ni site, Ni is bonded to two equivalent Sm and ten Ni atoms to form NiSm2Ni10 cuboctahedra that share corners with fourteen NiSm2Ni10 cuboctahedra, edges with six equivalent NiSm3Ni9 cuboctahedra, and faces with ten NiSm2Ni10 cuboctahedra. There are four shorter (2.39 Å) and four longer (2.41 Å) Ni–Ni bond lengths. In the third Ni site, Ni is bonded in a 12-coordinate geometry to two Sm and ten Ni atoms. There are a spread of Ni–Ni bond distances ranging from 2.38–2.54 Å. In the fourth Ni site, Ni is bonded to three Sm and nine Ni atoms to form a mixture of distorted edge, face, and corner-sharing NiSm3Ni9 cuboctahedra. Both Ni–Ni bond lengths are 2.41 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SmB7IO15 by Materials Project

SmB7O15I crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Sm is bonded in a 9-coordinate geometry to nine O atoms. There are a spread of Sm–O bond distances ranging from 2.25–2.77 Å. There are seven inequivalent B sites. In the first B site, B is bonded in a trigonal planar geometry to three O atoms. There is two shorter (1.37 Å) and one longer (1.39 Å) B–O bond length. In the second B site, B is bonded to four O atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.43–1.54 Å. In the third B site, B is bonded to four O atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.43–1.51 Å. In the fourth B site, B is bonded to four O atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.43–1.51 Å. In the fifth B site, B is bonded in a trigonal planar geometry to three O atoms. All B–O bond lengths are 1.37 Å. In the sixth B site, B is bonded in a trigonal planar geometry to three O atoms. There is one shorter (1.36 Å) and two longer (1.37 Å) B–O bond length. In the seventh B site, B is bonded in a trigonal planar geometry to three O atoms. There are a spread of B–O bond distances ranging from 1.36–1.38 Å. There are fifteen inequivalent O sites. In the first O site, O is bonded in a bent 120 degrees geometry to two B atoms. In the second O site, O is bonded in a distorted bent 120 degrees geometry to one Sm and two B atoms. In the third O site, O is bonded in a distorted bent 120 degrees geometry to one Sm and two B atoms. In the fourth O site, O is bonded in a trigonal planar geometry to three B atoms. In the fifth O site, O is bonded in a bent 120 degrees geometry to one Sm and two B atoms. In the sixth O site, O is bonded in a bent 120 degrees geometry to two B atoms. In the seventh O site, O is bonded in a bent 120 degrees geometry to two B atoms. In the eighth O site, O is bonded in a bent 120 degrees geometry to two B atoms. In the ninth O site, O is bonded in a distorted bent 120 degrees geometry to one Sm and two B atoms. In the tenth O site, O is bonded in a bent 120 degrees geometry to one Sm and one I atom. The O–I bond length is 1.96 Å. In the eleventh O site, O is bonded in a distorted bent 120 degrees geometry to one Sm and two B atoms. In the twelfth O site, O is bonded in a single-bond geometry to one Sm atom. In the thirteenth O site, O is bonded in a bent 120 degrees geometry to one Sm and two B atoms. In the fourteenth O site, O is bonded in a bent 120 degrees geometry to one Sm and one I atom. The O–I bond length is 2.23 Å. In the fifteenth O site, O is bonded in a single-bond geometry to one B atom. I is bonded in a 1-coordinate geometry to two O atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SrSm3 by Materials Project

SrSm3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sr is bonded to twelve Sm atoms to form SrSm12 cuboctahedra that share corners with four equivalent SrSm12 cuboctahedra, corners with eight equivalent SmSr4Sm8 cuboctahedra, edges with eight equivalent SrSm12 cuboctahedra, edges with sixteen equivalent SmSr4Sm8 cuboctahedra, faces with four equivalent SrSm12 cuboctahedra, and faces with fourteen SmSr4Sm8 cuboctahedra. All Sr–Sm bond lengths are 3.75 Å. There are two inequivalent Sm sites. In the first Sm site, Sm is bonded to four equivalent Sr and eight Sm atoms to form SmSr4Sm8 cuboctahedra that share corners with twelve equivalent SmSr4Sm8 cuboctahedra, edges with eight equivalent SrSm12 cuboctahedra, edges with sixteen SmSr4Sm8 cuboctahedra, faces with four equivalent SrSm12 cuboctahedra, and faces with fourteen SmSr4Sm8 cuboctahedra. All Sm–Sm bond lengths are 3.75 Å. In the second Sm site, Sm is bonded to four equivalent Sr and eight equivalent Sm atoms to form SmSr4Sm8 cuboctahedra that share corners with four equivalent SmSr4Sm8 cuboctahedra, corners with eight equivalent SrSm12 cuboctahedra, edges with twenty-four SmSr4Sm8 cuboctahedra, faces with six equivalent SrSm12 cuboctahedra, and faces with twelve SmSr4Sm8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm3(AgSn)4 by Materials Project

Sm3Ag4Sn4 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. there are two inequivalent Sm sites. In the first Sm site, Sm is bonded in a 12-coordinate geometry to six equivalent Ag and six Sn atoms. There are four shorter (3.31 Å) and two longer (3.44 Å) Sm–Ag bond lengths. There are two shorter (3.35 Å) and four longer (3.39 Å) Sm–Sn bond lengths. In the second Sm site, Sm is bonded to six Sn atoms to form distorted edge-sharing SmSn6 octahedra. There are four shorter (3.25 Å) and two longer (3.35 Å) Sm–Sn bond lengths. Ag is bonded in a 12-coordinate geometry to three equivalent Sm, one Ag, and four Sn atoms. The Ag–Ag bond length is 2.88 Å. There are a spread of Ag–Sn bond distances ranging from 2.76–2.88 Å. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 9-coordinate geometry to three Sm and six equivalent Ag atoms. In the second Sn site, Sn is bonded in a 9-coordinate geometry to six Sm, two equivalent Ag, and one Sn atom. The Sn–Sn bond length is 2.88 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm2Co17 by Materials Project

Sm2Co17 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Sm sites. In the first Sm site, Sm is bonded in a 12-coordinate geometry to eighteen Co atoms. There are a spread of Sm–Co bond distances ranging from 2.98–3.27 Å. In the second Sm site, Sm is bonded in a 2-coordinate geometry to twenty Co atoms. There are a spread of Sm–Co bond distances ranging from 2.91–3.16 Å. There are four inequivalent Co sites. In the first Co site, Co is bonded in a 2-coordinate geometry to one Sm and thirteen Co atoms. There are a spread of Co–Co bond distances ranging from 2.32–2.66 Å. In the second Co site, Co is bonded to two equivalent Sm and ten Co atoms to form CoSm2Co10 cuboctahedra that share corners with twenty-two CoSm2Co10 cuboctahedra, edges with ten CoSm3Co9 cuboctahedra, and faces with eighteen CoSm2Co10 cuboctahedra. There are four shorter (2.40 Å) and four longer (2.42 Å) Co–Co bond lengths. In the third Co site, Co is bonded to two Sm and ten Co atoms to form a mixture of distorted edge, face, and corner-sharing CoSm2Co10 cuboctahedra. There are a spread of Co–Co bond distances ranging from 2.34–2.58 Å. In the fourth Co site, Co is bonded to three Sm and nine Co atoms to form a mixture of distorted edge, face, and corner-sharing CoSm3Co9 cuboctahedra. Both Co–Co bond lengths are 2.44 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SmRh3 by Materials Project

SmRh3 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Sm sites. In the first Sm site, Sm is bonded in a 12-coordinate geometry to twelve Rh atoms. There are a spread of Sm–Rh bond distances ranging from 3.05–3.35 Å. In the second Sm site, Sm is bonded in a distorted hexagonal planar geometry to eighteen Rh atoms. There are six shorter (3.07 Å) and twelve longer (3.43 Å) Sm–Rh bond lengths. There are four inequivalent Rh sites. In the first Rh site, Rh is bonded to five Sm and seven Rh atoms to form a mixture of distorted corner, edge, and face-sharing RhSm5Rh7 cuboctahedra. There are a spread of Rh–Rh bond distances ranging from 2.65–2.72 Å. In the second Rh site, Rh is bonded in a 12-coordinate geometry to three equivalent Sm and six equivalent Rh atoms. In the third Rh site, Rh is bonded in a 12-coordinate geometry to three equivalent Sm and six equivalent Rh atoms. In the fourth Rh site, Rh is bonded to six equivalent Sm and six equivalent Rh atoms to form RhSm6Rh6 cuboctahedra that share corners with twelve equivalent RhSm5Rh7 cuboctahedra, edges with six equivalent RhSm6Rh6 cuboctahedra, and faces with eighteen equivalent RhSm5Rh7 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm2SbS by Materials Project

Sm2SbS is Caswellsilverite-like structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are two inequivalent Sm+2.50+ sites. In the first Sm+2.50+ site, Sm+2.50+ is bonded to two equivalent Sb3- and four equivalent S2- atoms to form a mixture of edge and corner-sharing SmSb2S4 octahedra. The corner-sharing octahedral tilt angles are 0°. Both Sm–Sb bond lengths are 3.02 Å. All Sm–S bond lengths are 3.02 Å. In the second Sm+2.50+ site, Sm+2.50+ is bonded to four equivalent Sb3- and two equivalent S2- atoms to form SmSb4S2 octahedra that share corners with six equivalent SmSb4S2 octahedra and edges with twelve SmSb2S4 octahedra. The corner-sharing octahedral tilt angles are 0°. All Sm–Sb bond lengths are 3.02 Å. Both Sm–S bond lengths are 3.02 Å. Sb3- is bonded to six Sm+2.50+ atoms to form SbSm6 octahedra that share corners with six equivalent SbSm6 octahedra, edges with four equivalent SbSm6 octahedra, and edges with eight equivalent SSm6 octahedra. The corner-sharing octahedral tilt angles are 0°. S2- is bonded to six Sm+2.50+ atoms to form SSm6 octahedra that share corners with six equivalent SSm6 octahedra, edges with four equivalent SSm6 octahedra, and edges with eight equivalent SbSm6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Elucidating the role of earth alkaline doping in perovskite-based methane dry reforming catalysts

To elucidate the role of earth alkaline doping in perovskite-based dry reforming of methane (DRM) catalysts, we embarked on a comparative and exemplary study of a Ni-based Sm perovskite with and without Sr doping. While the Sr-doped material appears as a structure-pure Sm 1.5 Sr 0.5 NiO 4 Ruddlesden Popper structure, the undoped material is a NiO/monoclinic Sm 2 O 3 composite. Hydrogen pre-reduction or direct activation in the DRM mixture in all cases yields either active Ni/Sm 2 O 3 or Ni/Sm 2 O 3 /SrCO 3 materials, with albeit different short-term stability and deactivation behavior. The much smaller Ni particle size after hydrogen reduction of Sm 1.5 Sr 0.5 NiO 4 , and of generally all undoped materials stabilizes the short and long-term DRM activity. Carbon dioxide reactivity manifests itself in the direct formation of SrCO 3 in the case of Sm 1.5 Sr 0.5 NiO 4 , which is dominant at high temperatures. For Sm 1.5 Sr 0.5 NiO 4 , the CO : H 2 ratio exceeds 1 at these temperatures, which is attributed to faster direct carbon dioxide conversion to SrCO 3 without catalytic DRM reactivity. As no Sm 2 O 2 CO 3 surface or bulk phase as a result of carbon dioxide activation was observed for any material – in contrast to La 2 O 2 CO 3 – we suggest that oxy-carbonate formation plays only a minor role for DRM reactivity. Rather, we identify surface graphitic carbon as the potentially reactive intermediate. Graphitic carbon has already been shown as a crucial reaction intermediate in metal-oxide DRM catalysts and appears both for Sm 1.5 Sr 0.5 NiO 4 and NiO/monoclinic Sm 2 O 3 after reaction as crystalline structure. It is significantly more pronounced for the latter due to the higher amount of oxygen-deficient monoclinic Sm 2 O 3 facilitating carbon dioxide activation. Despite the often reported beneficial role of earth alkaline dopants in DRM catalysis, we show that the situation is more complex. In our studies, the detrimental role of earth alkaline doping manifests itself in the exclusive formation of the sole stable carbonated species and a general destabilization of the Ni/monoclinic Sm 2 O 3 interface by favoring Ni particle sintering.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1994

Pre-bombardment crystallization ages of basaltic clasts from Antarctic howardites EET87503 and EET87513

Igneous clasts of basaltic eucrites are found in both howardites and polymict eucrites. We have studied the Rb-Sr and Sm-Nd isotopic systematics of a number of such clasts, of metamorphic grades 1-6, using the classification of Takeda and Graham. Here, we report Rb-Sr, (147)Sm-(143)Nd, and (145)Sm-(142)Nd studies of clast, 53 from Antarctic howardite EET87503. Although there is no evidence of disturbance of trace element systematics by Antarctic weathering, the Rb-Sr and conventional Sm-Nd isotopic systematics are severely disturbed, which we ascribe to thermal metamorphism. The Ar-Ar age spectrum shows ages ranging from approximately 3.85-3.55 Ga in an unusual 'down stairstep'. The (146)Sm-(142)Nd systematics, however, show the presence of live (146)Sm(t(sub 1/2) = 103 Ma), with (146)Sm/(144)Sm = 0.0061 +/- 0.0007 at the time of crystallization. This result is very similar to that previously obtained for basaltic clast, 18 from howardite EET87513 (paired with EET87503), which has concordant Rb-Sr and Sm-Nd ages of approximately 4.5 Ga. Thus, the two clasts are nearly the same age, and we conclude further than the EET87503,53 clast crystallized within 33 +/- 19 Ma of the LEW86010 angrite by comparing initial (146)Sm/(144)Sm to that of the angrite. We suggest that disturbances in the isotopic systematics of EET87503,53 are consanguineous with pyroxene homogenization.

Nyquist, L. E.↗
NASA NTRS2018

AMSR2 Soil Moisture Downscaling Using Temperature and Vegetation Data

Soil moisture (SM) applications in terrestrial hydrology require higher spatial resolution soil moisture products than those provided by passive microwave remote sensing instruments (grid resolution of 9 km or larger). In this investigation, an innovative algorithm that uses visible/infrared remote sensing observations to downscale Advanced Microwave Scanning Radiometer 2 (AMSR2) coarse spatial resolution SM products was developed and implemented for use with data provided by the Advanced Microwave Scanning Radiometer 2 (AMSR2). The method is based on using the Normalized Difference Vegetation Index (NDVI) modulated relationships between day/night SM and temperature change at corresponding times. Land surface model output variables from the North America Land Data Assimilation System (NLDAS), remote sensing data from the Moderate-Resolution Imaging Spectroradiometer (MODIS), and Advanced Very High Resolution Radiometer (AVHRR) were used in this methodology. The functional relationships developed using NLDAS data at a grid resolution of 12.5 km were applied to downscale AMSR2 JAXA (Japan Aerospace Exploration Agency) SM product (25 km) using MODIS land surface temperature (LST) and NDVI observations (1 km) to produce the 1 km SM estimates. The downscaled SM estimates were validated by comparing them with ISMN (International Soil Moisture Network) in situ SM in the Black Bear-Red Rock watershed, central Oklahoma between 2015-2017. The overall statistical variables of the downscaled AMSR2 SM validation R2, slope, RMSE and bias, demonstrate good accuracy. The downscaled SM better characterized the spatial and temporal variability of SM at watershed scales than the original SM product.

AMSR2; passive microwave soil moisture; soil moist↗
NASA NTRS2022

Multi-Frequency Radiometer-Based Soil Moisture Retrieval and Algorithm Parameterization Using In Situ Sites

L-band brightness temperature (TB) has been shown to provide the best sensitivity to soil moisture (SM) although C- and X-band based products offer a longer time-series from satellite-based measurements. Currently, global coverage SM is routinely produced from spaceborne measurements using all three frequency bands, but despite continued validation efforts of the products, the relative characteristics and performance of these observations have not been fully established. Therefore, this study focused on the parametrization of SM retrieval algorithms at L-, C- and X-bands using TB observations from the L-band radiometer on NASA's SM Active Passive (SMAP) mission and the C- and X-band channels of JAXA's Advanced Microwave Scanning Radiometer 2 (AMSR2) onboard the GCOM-W satellite. These can be applied in global SM retrieval algorithms using either one of the frequencies or a combination of them. The reference in situ SM data was obtained from 12 core validation sites across various land cover types around the world. The investigation highlighted the known challenges of retrieving SM from C- and X-band data compared to the higher sensitivity of the L-band data. Even with a site-specific retrieval algorithm parameterization, the mean correlation of the C- and X-band retrievals for the core validation site SM measurement were much lower than that for L-band, being 0.52 (0.54) and 0.45 (0.47) for vertical (horizontal) polarization, respectively, while for the L-band retrieval the corresponding values were 0.81 (0.77). The parameterization exercise showed that matching the C- and X-band TB measurements with an emission model was not difficult; the problem was relating the observations to SM under the influence of large roughness and vegetation effects. As a result, parameter optimization produced values for some sites that were not realistic or did not allow any practical sensitivity to SM at C- and X-band. Considering the L-band observations, the parameter optimization resulted in superior bias performance as compared to the operational SMAP product parameterization, but the sensitivity to SM changes (R and unbiased root mean square difference) did not improve markedly, or in some cases degraded at the expense of a smaller bias.

passive microwave↗
NASA NTRS2023

Assimilation of Blended Satellite Soil Moisture Data Products to Further Improve Noah-MP Model Skills

Microwave satellite remote sensing has enabled observations of soil moisture (SM) at the global scale, and multiple SM data products have been developed in the past decades. However, single-sensor-based measurements are insufficient for continuous spatiotemporal coverage. In the context of its climate program, the Climate Change Initiative, the European Space Agency (ESA) has developed robust, long term, global scale, multi instrument satellite derived time series of climate data record for key component of the climate system, including soil moisture (CCI), while the Soil Moisture Operational Product System (SMOPS) was specifically developed by National Oceanic and Atmospheric Administration (NOAA) to offer the real time blended SM datasets through merging all available individual products. Before combining, all individual SM data ingested into both SMOPS and CCI blended products are scaled to Global Land Data Assimilation System (GLDAS) 0-10 cm SM climatology. Benefiting from land surface model evolution and the availability of high-quality forcing data, GLDAS has become more comprehensive to track SM changes and dynamic trends. The development of GLDAS and the scaling procedure in CCI and SMOPS leave an open scientific and operational question: do the blended satellite SM data products have added value comparing to the GLDAS product? This study clearly reveals that both CCI and SMOPS can provide the reliable SM observations with independent information, although their climatology matches well with GLDAS. Relative to assimilation of GLDAS 0-10 cm SM data, Noah-MP model can be further improved by assimilating the blended satellite SM observations with respect to the quality-controlled in situ measurements. The strong consistency of results presented in this paper proves that the blended satellite SM data products are more useful than the GLDAS product in terms of improving Noah-MP model performance.

Jifu Yin↗
NASA NTRSDate not supplied

Systematic Errors in Simulated L-Band Brightness Temperature in the SMAP Level-4 Soil Moisture Analysis

The NASA Soil Moisture Active Passive (SMAP) mission has been providing L-band (1.4 GHz) brightness temperature (Tb) observations since April 2015. By assimilating the Tb observations into the NASA Catchment land surface model using a spatially distributed ensemble Kalman filter (EnKF), the SMAP Level-4 Soil Moisture (L4_SM) product provides global, 3-hourly, 9-km resolution estimates of surface (0-5 cm) and root-zone (0-100 cm) soil moisture with ~2.5-day latency for use in research and applications. The EnKF-based L4_SM analysis assumes unbiased forecast errors. Consequently, the seasonally varying bias between the model forecast Tb and the observed values is removed prior to the assimilation of the SMAP Tb observations. The L4_SM system is thus designed to only correct errors in synoptic-scale and interannual variations from the long-term mean seasonal cycle while maintaining the model’s (possibly wrong) climatology. In this paper, we examine the Tb observation-minus-forecast (O-F) residuals from the L4_SM Version 7 product (computed after rescaling the Tb observations to the mean seasonal cycle of the simulated Tb). The long-term average of the Tb O-F residuals has a global mean of only 0.13 K and locally small values, ranging from -1 to 3 K. The model forecast Tb, however, still exhibits undesirable systematic errors relative to the (rescaled) Tb observations. At some locations, the time-average Tb O-F values strongly depend on surface soil moisture (SM). At the Yanco SMAP core validation site, for example, the Tb O-F residuals typically range from 5 to 15 K under dry soil moisture conditions (SM < 0.15 m3 m-3) yet are predominantly negative under wet soil moisture conditions (SM > 0.25 m3 m-3), with values ranging from 0 to -40 K. This results in soil moisture analysis increments that persistently make the soil drier under dry SM conditions and persistently make the soil wetter under wet SM conditions, suggesting an error in the dynamic range of the simulated Tb, soil moisture or soil temperature. In this paper, we describe the higher-order systematic Tb forecast errors in more detail, examine their impact on the L4_SM product quality, and explore potential avenues to improve the L4_SM algorithm.

Rolf Reichle↗
DOE OSTI2020

Materials Data on SmZnSn by Materials Project

SmZnSn crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Sm sites. In the first Sm site, Sm is bonded to six equivalent Sn atoms to form edge-sharing SmSn6 octahedra. All Sm–Sn bond lengths are 3.23 Å. In the second Sm site, Sm is bonded in a 12-coordinate geometry to six equivalent Zn and six equivalent Sn atoms. All Sm–Zn bond lengths are 3.02 Å. All Sm–Sn bond lengths are 3.43 Å. Zn is bonded in a 6-coordinate geometry to three equivalent Sm and three equivalent Sn atoms. All Zn–Sn bond lengths are 2.72 Å. Sn is bonded in a 6-coordinate geometry to six Sm and three equivalent Zn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm3Ge5 by Materials Project

Sm3Ge5 crystallizes in the orthorhombic Fdd2 space group. The structure is three-dimensional. there are two inequivalent Sm sites. In the first Sm site, Sm is bonded in a 10-coordinate geometry to ten Ge atoms. There are a spread of Sm–Ge bond distances ranging from 3.04–3.46 Å. In the second Sm site, Sm is bonded in a 10-coordinate geometry to ten Ge atoms. There are a spread of Sm–Ge bond distances ranging from 3.02–3.48 Å. There are three inequivalent Ge sites. In the first Ge site, Ge is bonded in a 8-coordinate geometry to six Sm and two equivalent Ge atoms. There are one shorter (2.57 Å) and one longer (2.64 Å) Ge–Ge bond lengths. In the second Ge site, Ge is bonded in a 9-coordinate geometry to six Sm and three Ge atoms. The Ge–Ge bond length is 2.61 Å. In the third Ge site, Ge is bonded in a 8-coordinate geometry to six Sm and two equivalent Ge atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm2Ga2Fe15C by Materials Project

Sm2Fe15Ga2C crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Sm is bonded in a distorted single-bond geometry to thirteen Fe, one Ga, and one C atom. There are a spread of Sm–Fe bond distances ranging from 3.03–3.38 Å. The Sm–Ga bond length is 3.06 Å. The Sm–C bond length is 2.55 Å. There are six inequivalent Fe sites. In the first Fe site, Fe is bonded in a single-bond geometry to six Fe, one Ga, and one C atom. There are a spread of Fe–Fe bond distances ranging from 2.48–2.59 Å. The Fe–Ga bond length is 2.64 Å. The Fe–C bond length is 1.93 Å. In the second Fe site, Fe is bonded to three equivalent Sm, eight Fe, and one Ga atom to form FeSm3GaFe8 cuboctahedra that share corners with seventeen FeSm3GaFe8 cuboctahedra, corners with two equivalent CSm2Fe4 octahedra, edges with seven FeSm3GaFe8 cuboctahedra, faces with fourteen FeSm3GaFe8 cuboctahedra, and a faceface with one CSm2Fe4 octahedra. The corner-sharing octahedra tilt angles range from 65–71°. There are a spread of Fe–Fe bond distances ranging from 2.47–2.67 Å. The Fe–Ga bond length is 2.64 Å. In the third Fe site, Fe is bonded in a single-bond geometry to six Fe, two equivalent Ga, and one C atom. There are two shorter (2.46 Å) and two longer (2.49 Å) Fe–Fe bond lengths. Both Fe–Ga bond lengths are 2.80 Å. The Fe–C bond length is 1.84 Å. In the fourth Fe site, Fe is bonded to two equivalent Sm, eight Fe, and two equivalent Ga atoms to form distorted FeSm2Ga2Fe8 cuboctahedra that share corners with sixteen FeSm3GaFe8 cuboctahedra, corners with two equivalent CSm2Fe4 octahedra, edges with four FeSm3GaFe8 cuboctahedra, an edgeedge with one CSm2Fe4 octahedra, and faces with fifteen FeSm3GaFe8 cuboctahedra. The corner-sharing octahedra tilt angles range from 25–30°. There are two shorter (2.46 Å) and one longer (2.52 Å) Fe–Fe bond lengths. There are one shorter (2.82 Å) and one longer (2.83 Å) Fe–Ga bond lengths. In the fifth Fe site, Fe is bonded to two equivalent Sm, eight Fe, and two equivalent Ga atoms to form FeSm2Ga2Fe8 cuboctahedra that share corners with twelve FeSm3GaFe8 cuboctahedra, corners with two equivalent CSm2Fe4 octahedra, edges with eight FeSm3GaFe8 cuboctahedra, and faces with twelve FeSm3GaFe8 cuboctahedra. The corner-sharing octahedral tilt angles are 47°. Both Fe–Ga bond lengths are 2.61 Å. In the sixth Fe site, Fe is bonded to two equivalent Sm, eight Fe, and two equivalent Ga atoms to form distorted FeSm2Ga2Fe8 cuboctahedra that share corners with eighteen FeSm3GaFe8 cuboctahedra, edges with six FeSm3GaFe8 cuboctahedra, faces with fourteen FeSm3GaFe8 cuboctahedra, and faces with two equivalent CSm2Fe4 octahedra. Both Fe–Ga bond lengths are 2.61 Å. Ga is bonded in a 8-coordinate geometry to one Sm, twelve Fe, and one Ga atom. The Ga–Ga bond length is 2.59 Å. C is bonded to two equivalent Sm and four Fe atoms to form CSm2Fe4 octahedra that share corners with eighteen FeSm3GaFe8 cuboctahedra, edges with four equivalent FeSm2Ga2Fe8 cuboctahedra, and faces with eight FeSm3GaFe8 cuboctahedra.

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