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At least 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Fast and sensitive measurements of sub-3 nm particles using Condensation Particle Counters For Atmospheric Rapid Measurements (CPC FARM)

New particle formation (NPF) is the atmospheric process whereby gas molecules react and nucleate to form detectable particles. NPF has a strong impact on Earth's radiative balance as it produces roughly half of global cloud condensation nuclei. However, the time resolution and sensitivity of current instrumentation are inadequate in measuring the size distribution of sub-3 nm particles, the particles critical for understanding NPF. Here we present the Condensation Particle Counters For Atmospheric Rapid Measurements (CPC FARM), a method to measure the concentrations of freshly nucleated particles. The CPC FARM consists of five CPCs operating in parallel, each configured to operate at different detectable particle sizes between 1–3 nm. This study explores two methods to calculate the size distribution from the differential measurements across the CPC channels. The performance of both inversion methods was tested against the size distribution measured by a pair of stepping particle mobility sizers (SMPSs) during an ambient air sampling study in Pittsburgh, PA. Observational results indicate that the CPC FARM is more accurate with higher time resolution and sensitivity in the sub-3 nm range compared to the SMPS.

Cheng, Darren [Carnegie Mellon Univ., Pittsburgh, ↗
DOE OSTI2025

Self-Sensing Composites via an Embedded 3D-Printed PVDF-MoS 2 Nanosensor for Structural Health Monitoring

Carbon fiber (CF)-reinforced epoxy composites are widely used in vehicle applications, where early damage detection is crucial for reliability and safety. To address this need, we developed a self-sensing epoxy/CF composite by embedding a PVDF-MoS 2 nanosensor via an embedded 3D printing method. By harnessing the intrinsic curing kinetics of epoxy, we tailored its rheological properties to optimize the embedded printing process, enabling precise and reliable support for sensor filaments without compromising the composite’s structural and functional integrity. Through comprehensive rheological and kinetic analysis, we established a quantitative relationship among curing temperature, conversion rate, and resulting yield modulus─defining a narrow processing window essential for successful sensor integration. Specifically, we identified that an epoxy yield modulus range of 180–294 Pa and a conversion rate below 10% are critical to support the PVDF-MoS 2 filament architecture. Here, this embedded 3D printing method produces complex and multimaterial PVDF-MoS 2 sensors within an epoxy matrix with minimal deformation and reduced postprocessing, which is scalable and adaptable for industrial applications. Under cyclic loading, the embedded sensors exhibited stable signals under constant loads and increased voltage signals in response to crack formation (17–35% higher) and catastrophic failure (1 order of magnitude higher), effectively capturing structural changes in real time. This study demonstrates the potential of PVDF-MoS 2 nanocomposite sensor materials for real-time structural health monitoring in epoxy–CF composite systems, enabling early detection of defects and stress anomalies, significantly reducing the risk of unexpected failures, and enhancing structural reliability.

PVDF-MoS2 sensor↗
DOE OSTI2020

Materials Data on PaAs2 by Materials Project

PaAs2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Pa5+ is bonded in a 9-coordinate geometry to nine As+2.50- atoms. There are a spread of Pa–As bond distances ranging from 2.91–3.05 Å. There are two inequivalent As+2.50- sites. In the first As+2.50- site, As+2.50- is bonded to five equivalent Pa5+ atoms to form a mixture of distorted corner and edge-sharing AsPa5 square pyramids. In the second As+2.50- site, As+2.50- is bonded in a 8-coordinate geometry to four equivalent Pa5+ and four equivalent As+2.50- atoms. All As–As bond lengths are 2.84 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PaAs by Materials Project

PaAs is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Pa3+ is bonded to six equivalent As3- atoms to form a mixture of corner and edge-sharing PaAs6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Pa–As bond lengths are 2.90 Å. As3- is bonded to six equivalent Pa3+ atoms to form a mixture of corner and edge-sharing AsPa6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pa3Sb4 by Materials Project

Pa3Sb4 crystallizes in the cubic I-43d space group. The structure is three-dimensional. Pa4+ is bonded to eight equivalent Sb3- atoms to form a mixture of distorted corner, edge, and face-sharing PaSb8 hexagonal bipyramids. There are four shorter (3.14 Å) and four longer (3.21 Å) Pa–Sb bond lengths. Sb3- is bonded to six equivalent Pa4+ atoms to form a mixture of distorted corner, edge, and face-sharing SbPa6 octahedra. The corner-sharing octahedra tilt angles range from 15–51°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PaO2 by Materials Project

PaO2 is Fluorite structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Pa4+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Pa–O bond lengths are 2.36 Å. O2- is bonded to four equivalent Pa4+ atoms to form a mixture of edge and corner-sharing OPa4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pa3As4 by Materials Project

Pa3As4 crystallizes in the cubic I-43d space group. The structure is three-dimensional. Pa4+ is bonded to eight equivalent As3- atoms to form a mixture of distorted edge, face, and corner-sharing PaAs8 hexagonal bipyramids. There are four shorter (2.93 Å) and four longer (3.01 Å) Pa–As bond lengths. As3- is bonded to six equivalent Pa4+ atoms to form a mixture of distorted edge, face, and corner-sharing AsPa6 octahedra. The corner-sharing octahedra tilt angles range from 15–51°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PaCl4 by Materials Project

PaCl4 crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. Pa4+ is bonded in a 8-coordinate geometry to eight equivalent Cl1- atoms. There are four shorter (2.68 Å) and four longer (2.93 Å) Pa–Cl bond lengths. Cl1- is bonded in a distorted water-like geometry to two equivalent Pa4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PaCl5 by Materials Project

PaCl5 crystallizes in the monoclinic C2/c space group. The structure is one-dimensional and consists of two PaCl5 ribbons oriented in the (0, 0, 1) direction. Pa5+ is bonded to seven Cl1- atoms to form edge-sharing PaCl7 pentagonal bipyramids. There are a spread of Pa–Cl bond distances ranging from 2.49–2.80 Å. There are three inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Pa5+ atom. In the second Cl1- site, Cl1- is bonded in a water-like geometry to two equivalent Pa5+ atoms. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one Pa5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PaBr4 by Materials Project

PaBr4 crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. Pa4+ is bonded in a 8-coordinate geometry to eight equivalent Br1- atoms. There are four shorter (2.84 Å) and four longer (3.13 Å) Pa–Br bond lengths. Br1- is bonded in a distorted water-like geometry to two equivalent Pa4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na3PaF8 by Materials Project

Na3PaF8 is alpha bismuth trifluoride-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a body-centered cubic geometry to eight equivalent F1- atoms. All Na–F bond lengths are 2.45 Å. In the second Na1+ site, Na1+ is bonded in a body-centered cubic geometry to eight equivalent F1- atoms. All Na–F bond lengths are 2.46 Å. Pa5+ is bonded in a body-centered cubic geometry to eight equivalent F1- atoms. All Pa–F bond lengths are 2.22 Å. F1- is bonded to three Na1+ and one Pa5+ atom to form a mixture of edge and corner-sharing FNa3Pa tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PaBr5 by Materials Project

PaBr5 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of two PaBr5 clusters. Pa5+ is bonded to six Br1- atoms to form edge-sharing PaBr6 octahedra. There are a spread of Pa–Br bond distances ranging from 2.65–2.91 Å. There are five inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a single-bond geometry to one Pa5+ atom. In the second Br1- site, Br1- is bonded in a water-like geometry to two equivalent Pa5+ atoms. In the third Br1- site, Br1- is bonded in a single-bond geometry to one Pa5+ atom. In the fourth Br1- site, Br1- is bonded in a single-bond geometry to one Pa5+ atom. In the fifth Br1- site, Br1- is bonded in a single-bond geometry to one Pa5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on RbPaF6 by Materials Project

RbPaF6 crystallizes in the orthorhombic Cmme space group. The structure is two-dimensional and consists of two RbPaF6 sheets oriented in the (0, 1, 0) direction. Rb1+ is bonded in a distorted body-centered cubic geometry to eight equivalent F1- atoms. There are four shorter (3.01 Å) and four longer (3.08 Å) Rb–F bond lengths. Pa5+ is bonded in a body-centered cubic geometry to eight F1- atoms. There are four shorter (2.13 Å) and four longer (2.34 Å) Pa–F bond lengths. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted single-bond geometry to two equivalent Rb1+ and one Pa5+ atom. In the second F1- site, F1- is bonded in a bent 120 degrees geometry to two equivalent Pa5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GdPaO4 by Materials Project

PaGdO4 is Fluorite-derived structured and crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. Pa5+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Pa–O bond lengths are 2.31 Å. Gd3+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Gd–O bond lengths are 2.40 Å. O2- is bonded to two equivalent Pa5+ and two equivalent Gd3+ atoms to form a mixture of edge and corner-sharing OGd2Pa2 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K2PaF7 by Materials Project

K2PaF7 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. K1+ is bonded in a 9-coordinate geometry to nine F1- atoms. There are a spread of K–F bond distances ranging from 2.70–3.04 Å. Pa5+ is bonded in a 9-coordinate geometry to nine F1- atoms. There are a spread of Pa–F bond distances ranging from 2.18–2.55 Å. There are four inequivalent F1- sites. In the first F1- site, F1- is bonded in a 4-coordinate geometry to two equivalent K1+ and two equivalent Pa5+ atoms. In the second F1- site, F1- is bonded in a 1-coordinate geometry to three equivalent K1+ and one Pa5+ atom. In the third F1- site, F1- is bonded in a 4-coordinate geometry to three equivalent K1+ and one Pa5+ atom. In the fourth F1- site, F1- is bonded in a distorted trigonal planar geometry to two equivalent K1+ and one Pa5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YPaTc2 by Materials Project

PaYTc2 is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Pa3+ is bonded in a body-centered cubic geometry to eight equivalent Tc3- atoms. All Pa–Tc bond lengths are 2.97 Å. Y3+ is bonded in a body-centered cubic geometry to eight equivalent Tc3- atoms. All Y–Tc bond lengths are 2.97 Å. Tc3- is bonded in a body-centered cubic geometry to four equivalent Pa3+ and four equivalent Y3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BaPaO3 by Materials Project

BaPaO3 is (Cubic) Perovskite structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Ba2+ is bonded to twelve equivalent O2- atoms to form BaO12 cuboctahedra that share corners with twelve equivalent BaO12 cuboctahedra, faces with six equivalent BaO12 cuboctahedra, and faces with eight equivalent PaO6 octahedra. All Ba–O bond lengths are 3.19 Å. Pa4+ is bonded to six equivalent O2- atoms to form PaO6 octahedra that share corners with six equivalent PaO6 octahedra and faces with eight equivalent BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. All Pa–O bond lengths are 2.26 Å. O2- is bonded in a distorted linear geometry to four equivalent Ba2+ and two equivalent Pa4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PaC by Materials Project

PaC is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Pa4+ is bonded to six equivalent C4- atoms to form a mixture of corner and edge-sharing PaC6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Pa–C bond lengths are 2.54 Å. C4- is bonded to six equivalent Pa4+ atoms to form a mixture of corner and edge-sharing CPa6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗