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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on CePm3 by Materials Project

Pm3Ce is Copper-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Pm sites. In the first Pm site, Pm is bonded to eight Pm and four equivalent Ce atoms to form PmCe4Pm8 cuboctahedra that share corners with twelve equivalent PmCe4Pm8 cuboctahedra, edges with eight equivalent CePm12 cuboctahedra, edges with sixteen PmCe4Pm8 cuboctahedra, faces with four equivalent CePm12 cuboctahedra, and faces with fourteen PmCe4Pm8 cuboctahedra. There are four shorter (3.64 Å) and four longer (3.66 Å) Pm–Pm bond lengths. All Pm–Ce bond lengths are 3.66 Å. In the second Pm site, Pm is bonded to eight equivalent Pm and four equivalent Ce atoms to form PmCe4Pm8 cuboctahedra that share corners with four equivalent PmCe4Pm8 cuboctahedra, corners with eight equivalent CePm12 cuboctahedra, edges with twenty-four PmCe4Pm8 cuboctahedra, faces with six equivalent CePm12 cuboctahedra, and faces with twelve PmCe4Pm8 cuboctahedra. All Pm–Ce bond lengths are 3.64 Å. Ce is bonded to twelve Pm atoms to form CePm12 cuboctahedra that share corners with four equivalent CePm12 cuboctahedra, corners with eight equivalent PmCe4Pm8 cuboctahedra, edges with eight equivalent CePm12 cuboctahedra, edges with sixteen equivalent PmCe4Pm8 cuboctahedra, faces with four equivalent CePm12 cuboctahedra, and faces with fourteen PmCe4Pm8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pm3Hf by Materials Project

Pm3Hf is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Pm sites. In the first Pm site, Pm is bonded to eight Pm and four equivalent Hf atoms to form PmPm8Hf4 cuboctahedra that share corners with twelve equivalent PmPm8Hf4 cuboctahedra, edges with eight equivalent HfPm12 cuboctahedra, edges with sixteen PmPm8Hf4 cuboctahedra, faces with four equivalent HfPm12 cuboctahedra, and faces with fourteen PmPm8Hf4 cuboctahedra. All Pm–Pm bond lengths are 3.51 Å. All Pm–Hf bond lengths are 3.51 Å. In the second Pm site, Pm is bonded to eight equivalent Pm and four equivalent Hf atoms to form PmPm8Hf4 cuboctahedra that share corners with four equivalent PmPm8Hf4 cuboctahedra, corners with eight equivalent HfPm12 cuboctahedra, edges with twenty-four PmPm8Hf4 cuboctahedra, faces with six equivalent HfPm12 cuboctahedra, and faces with twelve PmPm8Hf4 cuboctahedra. All Pm–Hf bond lengths are 3.51 Å. Hf is bonded to twelve Pm atoms to form HfPm12 cuboctahedra that share corners with four equivalent HfPm12 cuboctahedra, corners with eight equivalent PmPm8Hf4 cuboctahedra, edges with eight equivalent HfPm12 cuboctahedra, edges with sixteen equivalent PmPm8Hf4 cuboctahedra, faces with four equivalent HfPm12 cuboctahedra, and faces with fourteen PmPm8Hf4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2024

The value of adding black carbon to community monitoring of particulate matter

Low-cost particulate matter (PM) sensors are increasingly used by researchers, public health agencies, and the public to measure spatial and temporal variations in air pollution, which can inform strategies for community air pollution reduction. While low-cost PM sensors provide a valuable measure of harmful fine particulate matter (PM 2.5 ), a significant portion of ambient PM 2.5 is typically the secondary product of air pollution emitted by varied sources outside of community boundaries. In contrast, concentrations of black carbon (BC), a component of PM 2.5 , are directly emitted by a few specific sources, such as diesel engines within communities. Motivated by community organizations seeking to understand persistent sources of local pollution, this study deployed a suite of custom-built BC sensors alongside a network of low-cost PM sensors for four weeks in two seasons at 50 stationary locations in the adjacent cities of Richmond, North Richmond, and San Pablo, California, east of the San Francisco Bay. Concentrations of BC varied more than PM 2.5 both temporally and spatially. Monthly network-average BC was 3×higher in winter than late spring, while PM 2.5 was only 10% lower. In both seasons, average PM 2.5 concentrations at two-thirds of sites were within ±10% of the network average, whereas two-thirds of sites had BC levels outside of ±10% of the network-average concentration. The most and least polluted locations were more persistent across seasons for BC than PM 2.5 , and the temporal dynamics of BC at these sites were similar, signifying that they are impacted by the same emission sources. Together, these spatiotemporal trends show that BC is a better indicator of the proximity and activity of local pollution sources than PM 2.5 . Thus, including BC in addition to PM 2.5 in community monitoring networks can provide additional insights about local sources of air pollution.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS2016

Variation in Global Chemical Composition of PM2.5: Emerging Results from SPARTAN

The Surface PARTiculate mAtter Network (SPARTAN) is a long-term project that includes characterization of chemical and physical attributes of aerosols from filter samples collected worldwide. This paper discusses the ongoing efforts of SPARTAN to define and quantify major ions and trace metals found in fine particulate matter (PM (sub 2.5). Our methods infer the spatial and temporal variability of PM (sub 2.5) in a cost-effective manner. Gravimetrically weighed filters represent multi-day averages of PM (sub 2.5), with a collocated nephelometer sampling air continuously. SPARTAN instruments are paired with AErosol RObotic NETwork (AERONET) sun photometers to better understand the relationship between ground-level PM (sub 2.5) and columnar aerosol optical depth (AOD). We have examined the chemical composition of PM (sub 2.5) at 12 globally dispersed, densely populated urban locations and a site at Mammoth Cave (US) National Park used as a background comparison. So far, each SPARTAN location has been active between the years 2013 and 2016 over periods of 2-26 months, with an average period of 12 months per site. These sites have collectively gathered over 10 years of quality aerosol data. The major PM (sub 2.5) constituents across all sites (relative contribution plus or minus Standard Deviation) are ammoniated sulfate (20 percent plus or minus 11 percent), crustal material (13.4 percent plus or minus 9.9 percent), equivalent black carbon (11.9 percent plus or minus 8.4 percent), ammonium nitrate (4.7 percent plus or minus 3.0 percent), sea salt (2.3 percent plus or minus 1.6 percent), trace element oxides (1.0 percent plus or minus 1.1 percent), water (7.2 percent plus or minus 3.3 percent) at 35 percent relative humidity, and residual matter (40 percent plus or minus 24 percent). Analysis of filter samples reveals that several PM (sub 2.5) chemical components varied by more than an order of magnitude between sites. Ammoniated sulfate ranges from 1.1 microns per cubic meter (Buenos Aires, Argentina) to 17 microns per cubic meter (Kanpur, India in the dry season). Ammonium nitrate ranged from 0.2 microns per cubic meter (Mammoth Cave, in summer) to 6.8 microns per cubic meter (Kanpur, dry season). Equivalent black carbon ranged from 0.7 microns per cubic meter (Mammoth Cave) to over 8 microns per cubic meter (Dhaka, Bangladesh and Kanpur, India). Comparison of SPARTAN vs. coincident measurements from the Interagency Monitoring of Protected Visual Environments (IMPROVE) network at Mammoth Cave yielded a high degree of consistency for daily PM (sub 2.5) (r squared equals 0.76, slope equals 1.12), daily sulfate (r squared equals 0.86, slope equals 1.03), and mean fractions of all major PM (sub 2.5) components (within 6 percent). Major ions generally agree well with previous studies at the same urban locations (e.g. sulfate fractions agree within 4 percent for 8 out of 11 collocation comparisons). Enhanced anthropogenic dust fractions in large urban areas (e.g. Singapore, Kanpur, Hanoi, and Dhaka) are apparent from high Zn to Al ratios. The expected water contribution to aerosols is calculated via the hygroscopicity parameter kappa (sub v (volume)) for each filter. Mean aggregate values ranged from 0.15 (Ilorin) to 0.28 (Rehovot). The all-site parameter mean is 0.20 plus or minus 0.04. Chemical composition and water retention in each filter measurement allows inference of hourly PM (sub 2.5) at 35 percent relative humidity by merging with nephelometer measurements. These hourly PM (sub 2.5) estimates compare favourably with a beta attenuation monitor (MetOne) at the nearby US embassy in Beijing, with a coefficient of variation r squared equals 0.67 (number equals 3167), compared to r squared equals 0.62 when v (volume) was not considered. SPARTAN continues to provide an open-access database of PM (sub 2.5) compositional filter information and hourly mass collected from a global federation of instruments.

Snider, Graydon↗
NASA NTRS2020

Assessment of Natural and Anthropogenic Aerosol Air Pollution In the Middle East Using MERRA-2, CAMS Data Assimilation Products, and High-Resolution WRF-Chem Model Simulations

Modern-Era Retrospective analysis for Research and Applications v.2 (MERRA-2), Copernicus Atmosphere Monitoring Service Operational Analysis (CAMS-OA), and a high-resolution regional Weather Research and Forecasting model coupled with chemistry (WRF-Chem) were used to evaluate natural and anthropogenic particulate matter (PM) air pollution in the Middle East (ME) during 2015–2016. Two Moderate Resolution Imaging Spectrometer (MODIS) retrievals – combined product Deep Blue and Deep Target (MODIS-DB&DT) and Multi-Angle Implementation of Atmospheric Correction (MAIAC) – and Aerosol Robotic Network (AERONET) aerosol optical depth (AOD) observations as well as in situ PM measurements for 2016 were used for validation of the WRF-Chem output and both assimilation products. MERRA-2 and CAMS-OA assimilate AOD observations. WRF-Chem is a free-running model, but dust emission in WRF-Chem is tuned to fit AOD and aerosol volume size distributions obtained from AERONET. MERRA-2 was used to construct WRF-Chem initial and boundary conditions both for meteorology and chemical and aerosol species. SO2 emissions in WRF-Chem are based on the novel OMI-HTAP SO2 emission dataset. The correlation with the AERONET AOD is highest for MERRA-2 (0.72–0.91), MAIAC (0.63–0.96), and CAMSOA (0.65–0.87), followed by MODIS-DB&DT (0.56–0.84) and WRF-Chem (0.43–0.85). However, CAMS-OA has a relatively high positive mean bias with respect to AERONET AOD. The spatial distributions of seasonally averaged AODs from WRF-Chem, assimilation products, and MAIAC are well correlated with MODIS-DB&DT AOD product. MAIAC has the highest correlation (R = 0.8), followed by MERRA-2 (R = 0.66), CAMS-OA (R = 0.65), and WRF-Chem (R = 0.61). WRF-Chem, MERRA-2, and MAIAC underestimate and CAMS-OA overestimates MODIS-DB&DT AOD. The simulated and observed PM concentrations might differ by a factor of 2 because it is more challenging for the model and the assimilation products to reproduce PM concentration measured within the city. Although aerosol fields in WRF-Chem and assimilation products are entirely consistent, WRF-Chem is preferable for analysis of regional air quality over the ME due to its higher spatial resolution and better SO2 emissions. The WRF-Chem’s PM background concentrations exceed the World Health Organization (WHO) guidelines over the entire ME. Mineral dust is the major contributor to PM (≈ 75%–95%) compared to other aerosol types. Near and downwind from the SO2 emission sources, non-dust aerosols (primarily sulfate) contribute up to 30% to PM(sub 2.5). The contribution of sea salt to PM in coastal regions can reach 5%. The contributions of organic matter, black carbon and organic carbon to PM over the Middle East are insignificant. In the major cities over the Arabian Peninsula, the 90th percentile of PM(sub 10) and PM(sub 2.5) (particles with diameters less than 10 and 2.5 μm, respectively) daily mean surface concentrations exceed the corresponding Kingdom of Saudi Arabia air quality limits. The contribution of the non-dust component to PM(sub 2.5) is < 25%, which limits the emission control effect on air quality. The mitigation of the dust effect on air quality requires the development of environment-based approaches like growing tree belts around the cities and enhancing in-city vegetation cover. The WRF-Chem configuration presented in this study could be a prototype of a future air quality forecast system that warns the population against air pollution hazards.

Alexander Ukhov↗
DOE OSTI2020

Materials Data on YbPm3 by Materials Project

YbPm3 is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Yb is bonded to twelve Pm atoms to form YbPm12 cuboctahedra that share corners with four equivalent YbPm12 cuboctahedra, corners with eight equivalent PmYb4Pm8 cuboctahedra, edges with eight equivalent YbPm12 cuboctahedra, edges with sixteen equivalent PmYb4Pm8 cuboctahedra, faces with four equivalent YbPm12 cuboctahedra, and faces with fourteen PmYb4Pm8 cuboctahedra. All Yb–Pm bond lengths are 3.67 Å. There are two inequivalent Pm sites. In the first Pm site, Pm is bonded to four equivalent Yb and eight Pm atoms to form PmYb4Pm8 cuboctahedra that share corners with twelve equivalent PmYb4Pm8 cuboctahedra, edges with eight equivalent YbPm12 cuboctahedra, edges with sixteen PmYb4Pm8 cuboctahedra, faces with four equivalent YbPm12 cuboctahedra, and faces with fourteen PmYb4Pm8 cuboctahedra. All Pm–Pm bond lengths are 3.67 Å. In the second Pm site, Pm is bonded to four equivalent Yb and eight equivalent Pm atoms to form PmYb4Pm8 cuboctahedra that share corners with four equivalent PmYb4Pm8 cuboctahedra, corners with eight equivalent YbPm12 cuboctahedra, edges with twenty-four PmYb4Pm8 cuboctahedra, faces with six equivalent YbPm12 cuboctahedra, and faces with twelve PmYb4Pm8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AcPm3 by Materials Project

AcPm3 is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ac is bonded to twelve Pm atoms to form AcPm12 cuboctahedra that share corners with four equivalent AcPm12 cuboctahedra, corners with eight equivalent PmAc4Pm8 cuboctahedra, edges with eight equivalent AcPm12 cuboctahedra, edges with sixteen equivalent PmAc4Pm8 cuboctahedra, faces with four equivalent AcPm12 cuboctahedra, and faces with fourteen PmAc4Pm8 cuboctahedra. There are four shorter (3.73 Å) and eight longer (3.74 Å) Ac–Pm bond lengths. There are two inequivalent Pm sites. In the first Pm site, Pm is bonded to four equivalent Ac and eight Pm atoms to form PmAc4Pm8 cuboctahedra that share corners with twelve equivalent PmAc4Pm8 cuboctahedra, edges with eight equivalent AcPm12 cuboctahedra, edges with sixteen PmAc4Pm8 cuboctahedra, faces with four equivalent AcPm12 cuboctahedra, and faces with fourteen PmAc4Pm8 cuboctahedra. There are four shorter (3.73 Å) and four longer (3.74 Å) Pm–Pm bond lengths. In the second Pm site, Pm is bonded to four equivalent Ac and eight equivalent Pm atoms to form PmAc4Pm8 cuboctahedra that share corners with four equivalent PmAc4Pm8 cuboctahedra, corners with eight equivalent AcPm12 cuboctahedra, edges with twenty-four PmAc4Pm8 cuboctahedra, faces with six equivalent AcPm12 cuboctahedra, and faces with twelve PmAc4Pm8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pm3Pa by Materials Project

PaPm3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Pa is bonded to twelve Pm atoms to form PaPm12 cuboctahedra that share corners with four equivalent PaPm12 cuboctahedra, corners with eight equivalent PmPm8Pa4 cuboctahedra, edges with eight equivalent PaPm12 cuboctahedra, edges with sixteen equivalent PmPm8Pa4 cuboctahedra, faces with four equivalent PaPm12 cuboctahedra, and faces with fourteen PmPm8Pa4 cuboctahedra. There are four shorter (3.52 Å) and eight longer (3.55 Å) Pa–Pm bond lengths. There are two inequivalent Pm sites. In the first Pm site, Pm is bonded to four equivalent Pa and eight Pm atoms to form PmPm8Pa4 cuboctahedra that share corners with twelve equivalent PmPm8Pa4 cuboctahedra, edges with eight equivalent PaPm12 cuboctahedra, edges with sixteen PmPm8Pa4 cuboctahedra, faces with four equivalent PaPm12 cuboctahedra, and faces with fourteen PmPm8Pa4 cuboctahedra. There are four shorter (3.52 Å) and four longer (3.55 Å) Pm–Pm bond lengths. In the second Pm site, Pm is bonded to four equivalent Pa and eight equivalent Pm atoms to form distorted PmPm8Pa4 cuboctahedra that share corners with four equivalent PmPm8Pa4 cuboctahedra, corners with eight equivalent PaPm12 cuboctahedra, edges with twenty-four PmPm8Pa4 cuboctahedra, faces with six equivalent PaPm12 cuboctahedra, and faces with twelve PmPm8Pa4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pm3Er by Materials Project

ErPm3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Er is bonded to twelve Pm atoms to form ErPm12 cuboctahedra that share corners with four equivalent ErPm12 cuboctahedra, corners with eight equivalent PmPm8Er4 cuboctahedra, edges with eight equivalent ErPm12 cuboctahedra, edges with sixteen equivalent PmPm8Er4 cuboctahedra, faces with four equivalent ErPm12 cuboctahedra, and faces with fourteen PmPm8Er4 cuboctahedra. There are four shorter (3.61 Å) and eight longer (3.63 Å) Er–Pm bond lengths. There are two inequivalent Pm sites. In the first Pm site, Pm is bonded to four equivalent Er and eight Pm atoms to form PmPm8Er4 cuboctahedra that share corners with twelve equivalent PmPm8Er4 cuboctahedra, edges with eight equivalent ErPm12 cuboctahedra, edges with sixteen PmPm8Er4 cuboctahedra, faces with four equivalent ErPm12 cuboctahedra, and faces with fourteen PmPm8Er4 cuboctahedra. There are four shorter (3.61 Å) and four longer (3.63 Å) Pm–Pm bond lengths. In the second Pm site, Pm is bonded to four equivalent Er and eight equivalent Pm atoms to form PmPm8Er4 cuboctahedra that share corners with four equivalent PmPm8Er4 cuboctahedra, corners with eight equivalent ErPm12 cuboctahedra, edges with twenty-four PmPm8Er4 cuboctahedra, faces with six equivalent ErPm12 cuboctahedra, and faces with twelve PmPm8Er4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pm3Gd by Materials Project

GdPm3 is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Gd is bonded to twelve Pm atoms to form GdPm12 cuboctahedra that share corners with four equivalent GdPm12 cuboctahedra, corners with eight equivalent PmPm8Gd4 cuboctahedra, edges with eight equivalent GdPm12 cuboctahedra, edges with sixteen equivalent PmPm8Gd4 cuboctahedra, faces with four equivalent GdPm12 cuboctahedra, and faces with fourteen PmPm8Gd4 cuboctahedra. There are four shorter (3.64 Å) and eight longer (3.65 Å) Gd–Pm bond lengths. There are two inequivalent Pm sites. In the first Pm site, Pm is bonded to four equivalent Gd and eight Pm atoms to form PmPm8Gd4 cuboctahedra that share corners with twelve equivalent PmPm8Gd4 cuboctahedra, edges with eight equivalent GdPm12 cuboctahedra, edges with sixteen PmPm8Gd4 cuboctahedra, faces with four equivalent GdPm12 cuboctahedra, and faces with fourteen PmPm8Gd4 cuboctahedra. There are four shorter (3.64 Å) and four longer (3.65 Å) Pm–Pm bond lengths. In the second Pm site, Pm is bonded to four equivalent Gd and eight equivalent Pm atoms to form PmPm8Gd4 cuboctahedra that share corners with four equivalent PmPm8Gd4 cuboctahedra, corners with eight equivalent GdPm12 cuboctahedra, edges with twenty-four PmPm8Gd4 cuboctahedra, faces with six equivalent GdPm12 cuboctahedra, and faces with twelve PmPm8Gd4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KPm3 by Materials Project

KPm3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. K is bonded to twelve Pm atoms to form KPm12 cuboctahedra that share corners with four equivalent KPm12 cuboctahedra, corners with eight equivalent PmK4Pm8 cuboctahedra, edges with eight equivalent KPm12 cuboctahedra, edges with sixteen equivalent PmK4Pm8 cuboctahedra, faces with four equivalent KPm12 cuboctahedra, and faces with fourteen PmK4Pm8 cuboctahedra. There are four shorter (3.72 Å) and eight longer (3.81 Å) K–Pm bond lengths. There are two inequivalent Pm sites. In the first Pm site, Pm is bonded to four equivalent K and eight Pm atoms to form PmK4Pm8 cuboctahedra that share corners with twelve equivalent PmK4Pm8 cuboctahedra, edges with eight equivalent KPm12 cuboctahedra, edges with sixteen PmK4Pm8 cuboctahedra, faces with four equivalent KPm12 cuboctahedra, and faces with fourteen PmK4Pm8 cuboctahedra. There are four shorter (3.72 Å) and four longer (3.81 Å) Pm–Pm bond lengths. In the second Pm site, Pm is bonded to four equivalent K and eight equivalent Pm atoms to form distorted PmK4Pm8 cuboctahedra that share corners with four equivalent PmK4Pm8 cuboctahedra, corners with eight equivalent KPm12 cuboctahedra, edges with twenty-four PmK4Pm8 cuboctahedra, faces with six equivalent KPm12 cuboctahedra, and faces with twelve PmK4Pm8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pm3Ho by Materials Project

HoPm3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ho is bonded to twelve Pm atoms to form HoPm12 cuboctahedra that share corners with four equivalent HoPm12 cuboctahedra, corners with eight equivalent PmPm8Ho4 cuboctahedra, edges with eight equivalent HoPm12 cuboctahedra, edges with sixteen equivalent PmPm8Ho4 cuboctahedra, faces with four equivalent HoPm12 cuboctahedra, and faces with fourteen PmPm8Ho4 cuboctahedra. There are four shorter (3.62 Å) and eight longer (3.63 Å) Ho–Pm bond lengths. There are two inequivalent Pm sites. In the first Pm site, Pm is bonded to four equivalent Ho and eight Pm atoms to form PmPm8Ho4 cuboctahedra that share corners with twelve equivalent PmPm8Ho4 cuboctahedra, edges with eight equivalent HoPm12 cuboctahedra, edges with sixteen PmPm8Ho4 cuboctahedra, faces with four equivalent HoPm12 cuboctahedra, and faces with fourteen PmPm8Ho4 cuboctahedra. There are four shorter (3.62 Å) and four longer (3.63 Å) Pm–Pm bond lengths. In the second Pm site, Pm is bonded to four equivalent Ho and eight equivalent Pm atoms to form PmPm8Ho4 cuboctahedra that share corners with four equivalent PmPm8Ho4 cuboctahedra, corners with eight equivalent HoPm12 cuboctahedra, edges with twenty-four PmPm8Ho4 cuboctahedra, faces with six equivalent HoPm12 cuboctahedra, and faces with twelve PmPm8Ho4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BaPm3 by Materials Project

BaPm3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ba is bonded to twelve Pm atoms to form BaPm12 cuboctahedra that share corners with four equivalent BaPm12 cuboctahedra, corners with eight equivalent PmBa4Pm8 cuboctahedra, edges with eight equivalent BaPm12 cuboctahedra, edges with sixteen equivalent PmBa4Pm8 cuboctahedra, faces with four equivalent BaPm12 cuboctahedra, and faces with fourteen PmBa4Pm8 cuboctahedra. There are eight shorter (3.77 Å) and four longer (3.83 Å) Ba–Pm bond lengths. There are two inequivalent Pm sites. In the first Pm site, Pm is bonded to four equivalent Ba and eight Pm atoms to form PmBa4Pm8 cuboctahedra that share corners with twelve equivalent PmBa4Pm8 cuboctahedra, edges with eight equivalent BaPm12 cuboctahedra, edges with sixteen PmBa4Pm8 cuboctahedra, faces with four equivalent BaPm12 cuboctahedra, and faces with fourteen PmBa4Pm8 cuboctahedra. There are four shorter (3.77 Å) and four longer (3.83 Å) Pm–Pm bond lengths. In the second Pm site, Pm is bonded to four equivalent Ba and eight equivalent Pm atoms to form PmBa4Pm8 cuboctahedra that share corners with four equivalent PmBa4Pm8 cuboctahedra, corners with eight equivalent BaPm12 cuboctahedra, edges with twenty-four PmBa4Pm8 cuboctahedra, faces with six equivalent BaPm12 cuboctahedra, and faces with twelve PmBa4Pm8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pm3Sm by Materials Project

SmPm3 is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sm is bonded to twelve Pm atoms to form SmPm12 cuboctahedra that share corners with four equivalent SmPm12 cuboctahedra, corners with eight equivalent PmPm8Sm4 cuboctahedra, edges with eight equivalent SmPm12 cuboctahedra, edges with sixteen equivalent PmPm8Sm4 cuboctahedra, faces with four equivalent SmPm12 cuboctahedra, and faces with fourteen PmPm8Sm4 cuboctahedra. All Sm–Pm bond lengths are 3.65 Å. There are two inequivalent Pm sites. In the first Pm site, Pm is bonded to four equivalent Sm and eight Pm atoms to form PmPm8Sm4 cuboctahedra that share corners with twelve equivalent PmPm8Sm4 cuboctahedra, edges with eight equivalent SmPm12 cuboctahedra, edges with sixteen PmPm8Sm4 cuboctahedra, faces with four equivalent SmPm12 cuboctahedra, and faces with fourteen PmPm8Sm4 cuboctahedra. All Pm–Pm bond lengths are 3.65 Å. In the second Pm site, Pm is bonded to four equivalent Sm and eight equivalent Pm atoms to form PmPm8Sm4 cuboctahedra that share corners with four equivalent PmPm8Sm4 cuboctahedra, corners with eight equivalent SmPm12 cuboctahedra, edges with twenty-four PmPm8Sm4 cuboctahedra, faces with six equivalent SmPm12 cuboctahedra, and faces with twelve PmPm8Sm4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pm3Tm by Materials Project

TmPm3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Tm is bonded to twelve Pm atoms to form TmPm12 cuboctahedra that share corners with four equivalent TmPm12 cuboctahedra, corners with eight equivalent PmPm8Tm4 cuboctahedra, edges with eight equivalent TmPm12 cuboctahedra, edges with sixteen equivalent PmPm8Tm4 cuboctahedra, faces with four equivalent TmPm12 cuboctahedra, and faces with fourteen PmPm8Tm4 cuboctahedra. There are four shorter (3.61 Å) and eight longer (3.62 Å) Tm–Pm bond lengths. There are two inequivalent Pm sites. In the first Pm site, Pm is bonded to four equivalent Tm and eight Pm atoms to form PmPm8Tm4 cuboctahedra that share corners with twelve equivalent PmPm8Tm4 cuboctahedra, edges with eight equivalent TmPm12 cuboctahedra, edges with sixteen PmPm8Tm4 cuboctahedra, faces with four equivalent TmPm12 cuboctahedra, and faces with fourteen PmPm8Tm4 cuboctahedra. There are four shorter (3.61 Å) and four longer (3.62 Å) Pm–Pm bond lengths. In the second Pm site, Pm is bonded to four equivalent Tm and eight equivalent Pm atoms to form PmPm8Tm4 cuboctahedra that share corners with four equivalent PmPm8Tm4 cuboctahedra, corners with eight equivalent TmPm12 cuboctahedra, edges with twenty-four PmPm8Tm4 cuboctahedra, faces with six equivalent TmPm12 cuboctahedra, and faces with twelve PmPm8Tm4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pm3Eu by Materials Project

EuPm3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Eu is bonded to twelve Pm atoms to form EuPm12 cuboctahedra that share corners with six equivalent EuPm12 cuboctahedra, corners with twelve PmPm8Eu4 cuboctahedra, edges with eighteen PmPm8Eu4 cuboctahedra, faces with eight equivalent EuPm12 cuboctahedra, and faces with twelve PmPm8Eu4 cuboctahedra. All Eu–Pm bond lengths are 3.71 Å. There are two inequivalent Pm sites. In the first Pm site, Pm is bonded to four equivalent Eu and eight Pm atoms to form PmPm8Eu4 cuboctahedra that share corners with four equivalent EuPm12 cuboctahedra, corners with fourteen PmPm8Eu4 cuboctahedra, edges with six equivalent EuPm12 cuboctahedra, edges with twelve PmPm8Eu4 cuboctahedra, faces with four equivalent EuPm12 cuboctahedra, and faces with sixteen PmPm8Eu4 cuboctahedra. There are a spread of Pm–Pm bond distances ranging from 3.64–3.78 Å. In the second Pm site, Pm is bonded to four equivalent Eu and eight equivalent Pm atoms to form PmPm8Eu4 cuboctahedra that share corners with four equivalent EuPm12 cuboctahedra, corners with fourteen PmPm8Eu4 cuboctahedra, edges with six equivalent EuPm12 cuboctahedra, edges with twelve equivalent PmPm8Eu4 cuboctahedra, faces with four equivalent EuPm12 cuboctahedra, and faces with sixteen PmPm8Eu4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Observationally constrained analysis on the distribution of fine- and coarse-mode nitrate in global models

Nitrate plays an important role in the Earth system and air quality. A key challenge in simulating the life cycle of nitrate aerosol in global models is to accurately represent mass size distribution of nitrate aerosol. In this study, we evaluate the performance of the Energy Exascale Earth System Model version 2 (E3SMv2) and the Community Earth System Model version 2 (CESM2), along with Aerosol Comparisons between Observations and Models (AeroCom) phase III models, in simulating spatial distribution of fine-mode nitrate, the mass size distribution of fine- and coarse-mode nitrate, and the gas–aerosol partitioning between nitric acid gas and nitrate, using long-term ground-based observations and measurements from multiple aircraft campaigns. We find that most models underestimate the annual mean PM 2.5 (particulate matter with diameter less than 2.5 µm) nitrate surface concentration averaged over all sites. The observed nitrate PM 2.5 / PM 10 and PM 1 / PM 4 ratios are influenced by the relative contribution of fine sulfate or organic particles and coarse dust or sea salt particles. Overall, the ground-based observations give an annual mean surface nitrate PM 2.5 / PM 10 ratio of 0.7. Most models underestimate the annual mean PM 2.5 / PM 10 ratio in all regions. There are large spreads in the modeled nitrate PM 1 / PM 4 ratios, which span the full range from 0 to 1. Most models underestimate the surface molar ratio of nitrate to total inorganic nitrate averaged across all sites. Our study indicates the importance of gas–aerosol partition parameterization and the simulation of dust and sea salt in correctly simulating the mass size distribution of nitrate.

Nitrate↗
DOE OSTI2023

Design and construction of the MUSE permanent magnet stellarator

This paper documents the design and construction of MUSE, the world's first permanent magnet (PM) stellarator and the first quasi-axisymmetric experiment. The purpose of MUSE is to develop and assess a new way of building optimised stellarators that uses simple planar coils PMs. Our PM optimisation algorithm consists of initialising a geometry to pack dipoles densely, running the FAMUS code to minimise surface field error subject to PM constraints and applying discrete jumps to reach a physically realisable solution. FAMUS treats the PM system as a set of ideal point dipoles. From there we construct finite-volume magnet towers to be housed in 3D-printed PM holders. We describe the design of the PM holders, which were validated by laser metrology. We analyse the effects of finite permeability, sensitivity to perturbations and magnetostatic forces. An exact analytic formula for the magnetic field from a finite-volume PM tower is presented to compute PM–PM forces and stress on the PM holder. Stellarator construction is complete and experiments are underway.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗