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At least 847 records · Page 47
All sourcesNASA NTRSDOE OSTI
NASA NTRS2007

Neuro-Motor Responses to Daily Centrifugation in Bed-Rested Subjects

It is well known from numerous space flight studies that exposure to micro-g produces both morphological and neural adaptations in the major postural muscles. However, the characteristics and mechanism of these changes, particularly when it may involve the central nervous system are not defined. Furthermore, it is not known what role unloading of the muscular system may have on central changes in sensorimotor function or if centrifugation along the +Gz direction (long body axis) can mitigate both the peripheral changes in muscle function and modification of the central changes in sensorimotor adaptation to the near weightless environment of space flight. The purpose of this specific effort was, therefore, to investigate the efficacy of artificial gravity (AG) as a method for maintaining sensorimotor function in micro-g. Eight male subjects were exposed to daily 1 hr centrifugation during a 21 day 6 degree head-down bed rest study. Seven controls were placed on the centrifuge without rotation. The radius and angular velocity of the centrifuge were adjusted such that each subject experienced a centripetal acceleration of 2.5g at the feet, and approximately 1.0g at the heart. Both the tendon (MSR) and functional stretch reflexes (FSR) were collected using an 80 lb. ft. servomotor controlled via position feedback to provide a dorsiflexion step input to elicit the MSR, and the same step input with a built in 3 sec hold to evoke the FSR. EMG data were obtained from the triceps surae. Supplementary torque, velocity and position data were collected with the EMG responses. All data were digitized and sampled at 4 kHz. Only the MSR data has been analyzed at this time, and preliminary results suggest that those subjects exposed to active centrifugation (treatment group) show only minor changes in MSR peak latency times, either as a function of time spent in bed rest or exposure to centrifugation, while the control subjects show delays in the MSR peak latencies that are typical of bed rested subjects. There also appears to be a trend in the treatment group where centrifugation results in peak latencies that are shorter than the control group. This trend is supported by the observation that peak reflex amplitudes are larger (up to 40% in magnitude)than those of the control subjects. Furthermore, centrifugation tends, by day 21 of bed rest, to normalize the peak amplitudes to the amplitudes observed prior to bed rest or centrifugation. From a preliminary point of view, centrifugation appears to have a positive effect on the sensorimotor system, and specifically on those muscles that provide anti-gravity and postural support.

Reschke, Millard F.↗
DOE OSTI2020

Materials Data on Si2Ag6O7 by Materials Project

Ag6Si2O7 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are twelve inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a distorted T-shaped geometry to three O2- atoms. There are a spread of Ag–O bond distances ranging from 2.19–2.57 Å. In the second Ag1+ site, Ag1+ is bonded in a distorted T-shaped geometry to three O2- atoms. There are a spread of Ag–O bond distances ranging from 2.18–2.46 Å. In the third Ag1+ site, Ag1+ is bonded in a 2-coordinate geometry to four O2- atoms. There are a spread of Ag–O bond distances ranging from 2.22–2.84 Å. In the fourth Ag1+ site, Ag1+ is bonded in a distorted see-saw-like geometry to four O2- atoms. There are a spread of Ag–O bond distances ranging from 2.29–2.70 Å. In the fifth Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Ag–O bond distances ranging from 2.28–2.77 Å. In the sixth Ag1+ site, Ag1+ is bonded in a 2-coordinate geometry to four O2- atoms. There are a spread of Ag–O bond distances ranging from 2.25–2.84 Å. In the seventh Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Ag–O bond distances ranging from 2.28–2.76 Å. In the eighth Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Ag–O bond distances ranging from 2.36–2.67 Å. In the ninth Ag1+ site, Ag1+ is bonded in a 2-coordinate geometry to three O2- atoms. There are a spread of Ag–O bond distances ranging from 2.16–2.78 Å. In the tenth Ag1+ site, Ag1+ is bonded in a T-shaped geometry to three O2- atoms. There are a spread of Ag–O bond distances ranging from 2.25–2.43 Å. In the eleventh Ag1+ site, Ag1+ is bonded in a distorted T-shaped geometry to three O2- atoms. There are a spread of Ag–O bond distances ranging from 2.19–2.58 Å. In the twelfth Ag1+ site, Ag1+ is bonded in a distorted linear geometry to two O2- atoms. There are one shorter (2.18 Å) and one longer (2.20 Å) Ag–O bond lengths. There are four inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.64–1.68 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.63–1.68 Å. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.64–1.67 Å. In the fourth Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.64–1.67 Å. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to four Ag1+ and one Si4+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to three Ag1+ and one Si4+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to three Ag1+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ag1+ and two Si4+ atoms. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to two Ag1+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to three Ag1+ and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to three Ag1+ and one Si4+ atom. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to three Ag1+ and one Si4+ atom. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to three Ag1+ and one Si4+ atom. In the tenth O2- site, O2- is bonded in a 1-coordinate geometry to four Ag1+ and one Si4+ atom. In the eleventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ag1+ and two Si4+ atoms. In the twelfth O2- site, O2- is bonded in a 1-coordinate geometry to four Ag1+ and one Si4+ atom. In the thirteenth O2- site, O2- is bonded in a distorted tetrahedral geometry to three Ag1+ and one Si4+ atom. In the fourteenth O2- site, O2- is bonded in a 1-coordinate geometry to four Ag1+ and one Si4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TbAgH10C20(N3O4)2 by Materials Project

Tb(CO2)4AgH4(CN)6(C)4(CH)6 crystallizes in the monoclinic C2/c space group. The structure is one-dimensional and consists of sixteen methane molecules; twenty-four methane molecules; four AgH4(CN)6 clusters; and two Tb(CO2)4 ribbons oriented in the (0, 0, 1) direction. In each AgH4(CN)6 cluster, Ag1+ is bonded in a distorted linear geometry to two equivalent N3- atoms. Both Ag–N bond lengths are 2.11 Å. There are three inequivalent C1+ sites. In the first C1+ site, C1+ is bonded in a trigonal planar geometry to two N3- and one H1+ atom. There is one shorter (1.32 Å) and one longer (1.36 Å) C–N bond length. The C–H bond length is 1.08 Å. In the second C1+ site, C1+ is bonded in a trigonal planar geometry to two N3- and one H1+ atom. There is one shorter (1.31 Å) and one longer (1.37 Å) C–N bond length. The C–H bond length is 1.08 Å. In the third C1+ site, C1+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.43 Å. There are three inequivalent N3- sites. In the first N3- site, N3- is bonded in a trigonal planar geometry to three C1+ atoms. In the second N3- site, N3- is bonded in a 3-coordinate geometry to one Ag1+, one C1+, and one N3- atom. The N–N bond length is 1.38 Å. In the third N3- site, N3- is bonded in a distorted single-bond geometry to one C1+ and one N3- atom. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C1+ atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C1+ atom. In each Tb(CO2)4 ribbon, Tb3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Tb–O bond distances ranging from 2.32–2.50 Å. There are two inequivalent C1+ sites. In the first C1+ site, C1+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.27 Å) and one longer (1.28 Å) C–O bond length. In the second C1+ site, C1+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.26 Å) and one longer (1.27 Å) C–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Tb3+ and one C1+ atom. In the second O2- site, O2- is bonded in a distorted linear geometry to one Tb3+ and one C1+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to one Tb3+ and one C1+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to one Tb3+ and one C1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AgBi3S5 by Materials Project

AgBi3S5 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded to six S2- atoms to form AgS6 octahedra that share corners with two equivalent BiS6 octahedra, corners with four equivalent BiS5 square pyramids, edges with two equivalent AgS6 octahedra, and edges with six equivalent BiS5 square pyramids. The corner-sharing octahedral tilt angles are 54°. There are two shorter (2.58 Å) and four longer (2.91 Å) Ag–S bond lengths. In the second Ag1+ site, Ag1+ is bonded to six S2- atoms to form AgS6 octahedra that share corners with four equivalent BiS6 octahedra, edges with two equivalent AgS6 octahedra, and edges with ten BiS6 octahedra. The corner-sharing octahedral tilt angles are 6°. There are two shorter (2.54 Å) and four longer (3.07 Å) Ag–S bond lengths. There are three inequivalent Bi3+ sites. In the first Bi3+ site, Bi3+ is bonded to five S2- atoms to form distorted BiS5 square pyramids that share corners with two equivalent AgS6 octahedra, corners with two equivalent BiS6 octahedra, edges with three equivalent AgS6 octahedra, and edges with four equivalent BiS5 square pyramids. The corner-sharing octahedra tilt angles range from 14–64°. There are a spread of Bi–S bond distances ranging from 2.61–2.87 Å. In the second Bi3+ site, Bi3+ is bonded to six S2- atoms to form BiS6 octahedra that share a cornercorner with one AgS6 octahedra, corners with three equivalent BiS6 octahedra, corners with two equivalent BiS5 square pyramids, edges with two equivalent AgS6 octahedra, and edges with five BiS6 octahedra. The corner-sharing octahedra tilt angles range from 9–54°. There are a spread of Bi–S bond distances ranging from 2.70–3.00 Å. In the third Bi3+ site, Bi3+ is bonded to six S2- atoms to form BiS6 octahedra that share corners with two equivalent AgS6 octahedra, corners with three equivalent BiS6 octahedra, edges with three equivalent AgS6 octahedra, and edges with seven BiS6 octahedra. The corner-sharing octahedra tilt angles range from 6–16°. There are a spread of Bi–S bond distances ranging from 2.75–2.94 Å. There are five inequivalent S2- sites. In the first S2- site, S2- is bonded to two equivalent Ag1+ and three equivalent Bi3+ atoms to form a mixture of distorted edge and corner-sharing SAg2Bi3 square pyramids. In the second S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to one Ag1+ and three Bi3+ atoms. In the third S2- site, S2- is bonded in a 3-coordinate geometry to three Bi3+ atoms. In the fourth S2- site, S2- is bonded to one Ag1+ and four Bi3+ atoms to form SAgBi4 square pyramids that share corners with two equivalent SAg2Bi4 octahedra, a cornercorner with one SAgBi4 square pyramid, edges with five equivalent SAg2Bi4 octahedra, and edges with two equivalent SAgBi4 square pyramids. The corner-sharing octahedral tilt angles are 9°. In the fifth S2- site, S2- is bonded to two equivalent Ag1+ and four Bi3+ atoms to form SAg2Bi4 octahedra that share corners with two equivalent SAg2Bi4 octahedra, corners with two equivalent SAgBi4 square pyramids, edges with five equivalent SAg2Bi4 octahedra, and edges with five equivalent SAgBi4 square pyramids. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Thermal and kinematic properties of ejecta in SN1987A revealed by XRISM

We present an analysis of high-resolution spectra from the shock-heated plasmas in SN 1987A, based on an observation using the Resolve instrument onboard the X-Ray Imaging and Spectroscopy Mission (XRISM). The 1.7–10 keV Resolve spectra are accurately represented by a single-component, plane-parallel shock plasma model, with a temperature of $2.84_{-0.08}^{+0.09}$ keV and an ionization parameter of $2.64_{-0.45}^{+0.58}$ × $10^{11}\,\,{\rm s\,\, cm}^{-3}$. The Resolve spectra are also well reproduced by the 3D magneto-hydrodynamic simulation presented by Orlando et al. (2020, A&A, 636, A22) suggesting substantial contribution from the ejecta. The metal abundances obtained with Resolve align with the Large Magellanic Cloud value, indicating that the X-rays in 2024 originate from “non-metal-rich” shock-heated ejecta and the reverse shock has not reached the inner metal-rich region of ejecta. Doppler widths of the atomic lines from Si, S, and Fe correspond to velocities of 1500–1700 km s$^{-1}$, where the thermal broadening effects in this non-metal-rich plasma are negligible. Therefore, the line broadening seen in Resolve spectra is determined by the large bulk motion of ejecta. For reference, we determined a $90\%$ upper limit on non-thermal emission from a pulsar wind nebula at $4.3 \times 10^{-13}$ erg cm$^{-2}$ s$^{-1}$ in the 2–10 keV range, aligning with NuSTAR findings by Greco et al. (2022, ApJ, 931, 132). Additionally, we searched for the $^{44}$Sc K line feature and found a $1\sigma$ upper limit of $1.0 \times 10^{-6}$ photons cm$^{-2}$ s$^{-1}$, which translates to an initial $^{44}$Ti mass of approximately $2 \times 10^{-4}\, M_{\odot }$, consistent with previous X-ray to soft gamma-ray observations (Boggs et al. 2015, Science, 348, 670; Grebenev et al. 2012, Nature, 490, 373; Leising 2006, ApJ, 651, 1019).

ISM: supernova remnants↗
DOE OSTI2020

Materials Data on NaAgTe5O14 by Materials Project

NaAgTe5O14 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Na1+ is bonded to eight O2- atoms to form distorted NaO8 hexagonal bipyramids that share corners with four TeO5 square pyramids and edges with six TeO6 octahedra. There are a spread of Na–O bond distances ranging from 2.28–2.80 Å. Ag1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ag–O bond distances ranging from 2.48–2.91 Å. There are six inequivalent Te+5.20+ sites. In the first Te+5.20+ site, Te+5.20+ is bonded to six O2- atoms to form TeO6 octahedra that share corners with four TeO6 octahedra, corners with two TeO5 square pyramids, and edges with two equivalent NaO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 41–44°. There are a spread of Te–O bond distances ranging from 1.92–1.99 Å. In the second Te+5.20+ site, Te+5.20+ is bonded to five O2- atoms to form distorted TeO5 square pyramids that share corners with two equivalent NaO8 hexagonal bipyramids, corners with three TeO6 octahedra, and an edgeedge with one TeO5 square pyramid. The corner-sharing octahedra tilt angles range from 39–58°. There are a spread of Te–O bond distances ranging from 1.92–2.45 Å. In the third Te+5.20+ site, Te+5.20+ is bonded to six O2- atoms to form TeO6 octahedra that share corners with four TeO6 octahedra, corners with two equivalent TeO5 square pyramids, and edges with two equivalent NaO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 39–44°. There are a spread of Te–O bond distances ranging from 1.91–1.99 Å. In the fourth Te+5.20+ site, Te+5.20+ is bonded to five O2- atoms to form distorted TeO5 square pyramids that share corners with two equivalent NaO8 hexagonal bipyramids, corners with three TeO6 octahedra, and an edgeedge with one TeO5 square pyramid. The corner-sharing octahedra tilt angles range from 44–59°. There are a spread of Te–O bond distances ranging from 1.89–2.33 Å. In the fifth Te+5.20+ site, Te+5.20+ is bonded to six O2- atoms to form TeO6 octahedra that share corners with four TeO6 octahedra, corners with two equivalent TeO5 square pyramids, and edges with two equivalent NaO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 41–44°. There are a spread of Te–O bond distances ranging from 1.92–2.00 Å. In the sixth Te+5.20+ site, Te+5.20+ is bonded to six O2- atoms to form TeO6 octahedra that share corners with four TeO6 octahedra, corners with two equivalent TeO5 square pyramids, and edges with two equivalent NaO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 41–43°. There are a spread of Te–O bond distances ranging from 1.95–1.98 Å. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Ag1+ and two Te+5.20+ atoms. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to two Te+5.20+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ag1+ and two Te+5.20+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and two equivalent Te+5.20+ atoms. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+ and two Te+5.20+ atoms. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and two Te+5.20+ atoms. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Ag1+ and two Te+5.20+ atoms. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to two Te+5.20+ atoms. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+, one Ag1+, and two Te+5.20+ atoms. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ag1+ and two Te+5.20+ atoms. In the eleventh O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Na1+ and two Te+5.20+ atoms. In the twelfth O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+ and two Te+5.20+ atoms. In the thirteenth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Ag1+, and two Te+5.20+ atoms. In the fourteenth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Ag1+, and two Te+5.20+ atoms.

36 MATERIALS SCIENCE↗
NASA NTRS1979

Breccias 73215 and 73255 - Siderophile and volatile trace elements

Fifteen siderophile and volatile trace elements (Os, Re, Ir, Pd, Ni, Au, Sb, Ge, Se, Ag, In, Zn, Cd, Bi, Tl) and U were determined by radiochemical neutron activation analysis in a spheroidal aphanitic clast and a clast of coarse-grained anorthositic gabbro from breccia 73215 and in three types of aphanite and two clasts of fine-grained anorthositic gabbro from breccia 73255. In common with most Apollo 17 fragment-laden melt rocks, the aphanites from 73215 and 73255 predominantly contain a Group 2 meteoritic component, which is apparently derived from the Serenitatis impact. All aphanitic lithologies contain the same meteoritic component, and are probably cogenetic. The clasts of fine-grained anorthositic gabbro contain substantial amounts (2% to 6% Cl equivalent based on Au) of a pre-Serenitatis Group 3 component. The clast of coarse-grained anorthositic gabbro is low in siderophile elements (0.4% Cl equivalent), and the meteoritic component (Group 5) is not well-defined. A strong correlation exists between Ir and Au in both the aphanites and the anorthositic gabbro clasts, which argues against the breccias 73215 and 73255 being open systems for Au

Morgan, J. W.↗
DOE OSTI2020

Materials Data on NiAg4P6(HO3)6 by Materials Project

NiAg4P6(HO3)6 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Ni2+ is bonded to six H atoms to form NiH6 octahedra that share corners with two equivalent AgHO4 trigonal bipyramids. There is two shorter (1.55 Å) and four longer (1.58 Å) Ni–H bond length. There are two inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Ag–O bond distances ranging from 2.26–2.52 Å. In the second Ag1+ site, Ag1+ is bonded to one H and four O2- atoms to form distorted AgHO4 trigonal bipyramids that share a cornercorner with one NiH6 octahedra, corners with four PO4 tetrahedra, and an edgeedge with one AgHO4 trigonal bipyramid. The corner-sharing octahedral tilt angles are 19°. The Ag–H bond length is 1.83 Å. There are a spread of Ag–O bond distances ranging from 2.32–2.46 Å. There are three inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two PO4 tetrahedra and corners with three equivalent AgHO4 trigonal bipyramids. There are a spread of P–O bond distances ranging from 1.50–1.63 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two PO4 tetrahedra and a cornercorner with one AgHO4 trigonal bipyramid. There are a spread of P–O bond distances ranging from 1.49–1.62 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.48–1.66 Å. There are three inequivalent H sites. In the first H site, H is bonded in a 2-coordinate geometry to one Ni2+ and one H atom. The H–H bond length is 0.83 Å. In the second H site, H is bonded in a 3-coordinate geometry to one Ni2+, one H, and one O2- atom. The H–O bond length is 2.25 Å. In the third H site, H is bonded in a bent 150 degrees geometry to one Ni2+ and one Ag1+ atom. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one Ag1+ and one P5+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the third O2- site, O2- is bonded in a 1-coordinate geometry to two Ag1+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to one Ag1+, one P5+, and one H atom. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the seventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ag1+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ag1+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a distorted single-bond geometry to two Ag1+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Fundamental Thermodynamic, Kinetic, and Mechanical Properties of Lithium and Its Alloys

Lithium alloying reactions are beneficial in promoting uniform plating and stripping of lithium metal in all-solid-state batteries. First-principles calculations are performed to predict thermodynamic, kinetic, and mechanical properties of lithium and several important Li–M alloys (M = Mg, Ag, Zn, Al, Ga, In, Sn, Sb, and Bi). While the Li–Mg binary system forms a solid solution, most other lithium–metal alloys prefer stoichiometric intermetallic compounds with common local motifs that enable fast Li diffusion. Lithium and Li-rich alloys exhibit an unusually flat energy landscape along paths that connect BCC to close-packed structures like FCC and HCP, with important implications for mechanical properties. Very low migration barriers for Li diffusion that rival those of superion conductors are predicted, both in pure Li and in Li–M intermetallics. However, vacancy concentration, which is crucial for substitutional diffusion, is predicted to be low in metallic Li and most Li–M intermetallics. Compounds such as B32 LiAl and LiGa as well as D0 3 Li 3 Sb and Li 3 Bi exhibit structural vacancies at higher ends of their voltage windows, which together with low migration barriers leads to exceptionally high Li mobilities. In the Li–Mg solid solution, the addition of Mg is found to decrease the vacancy tracer diffusion coefficient by an order of magnitude.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Understanding and Overcoming Water-induced Interfacial Degradation in Si Modules (Final Technical Report)

Moisture ingress is an established issue for photovoltaic module durability. Durability studies probing moisture effects typically evaluate performance losses at the module level, attributing global power losses to the overall humidity condition of the test environment while leaving local module behavior unknown. This project successfully develops an in situ short-wave infrared probe of moisture content in PV modules with demonstrated detection limits better than 100 ppm in EVA-encapsulated Al-BSF and PERC architectures (66 µg/cm3) and applicability across the range of terrestrial conditions. Combining this optical moisture quantification method (water reflectometry detection, WaRD) with peel testing of interfaces, biased photoluminescence imaging of performance, and first principles computation, we correlate module moisture content and cell performance over the course of accelerated damp heat tests. By performing multi-level humidity and thermal accelerated testing over thousands of hours (0, 65 and 85% RH and 25, 65, and 85°C), we are able to attribute effects of individual environmental stresses and the dependence on module architecture. Using first-principles computational chemistry, we find that the decomposition of EVA to acetic acid (Norrish II) is thermodynamically preferred over a pathway to acetaldehyde (Norrish I), elucidating the underlying chemistry of encapsulant degradation. We also find it is likely that water segregates to the stable interfaces of the cell, especially the SiNx/EVA interface. We find that moisture is strongly correlated with reduction in adhesion at the interfaces of the cells, particularly at Ag fingers. We show uniquely that the peel strength required to delaminate the encapsulant from the front of the cell depends not only on the exposure to a high heat and humid environment, but also to the moisture content during the mechanical testing, indicating an important interaction between when mechanical stresses are faced in terms of the moisture content of the module and its durability. We find that the background sheet resistance (that is, the sheet resistance rise not attributable to finger interruptions or cracks) is substantially higher in the backsheet mini-modules vs glass-glass packages when humidity and temperature are faced. This increase in power loss due to the background resistance increase over time in damp heat in glass-backsheet modules resulted in ~3-4% larger decrease in relative PCE compared to glass-glass modules. In glass-backsheet modules, the effect of the moisture dose alone is comparable or greater than that of the combined temperature and water term, suggesting that glass-backsheet modules are overall more susceptible to moisture induced performance loss. Finally, we show that thin film PV modules are amenable to WaRD measurement, based on the ability to detect moisture in POE encapsulants or in the cell stack itself. The ease of WaRD measurement and its few requirements on the bill of materials should enable broad applicability of this technique for studying the effects of moisture in PV.

14 SOLAR ENERGY↗
DOE OSTI2020

Materials Data on Ag3Bi8S13 by Materials Project

Ag3Bi8S13 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded to six S2- atoms to form AgS6 octahedra that share a cornercorner with one AgS6 octahedra, corners with four BiS6 octahedra, edges with two equivalent AgS6 octahedra, and edges with ten BiS6 octahedra. The corner-sharing octahedra tilt angles range from 0–6°. There are a spread of Ag–S bond distances ranging from 2.67–2.99 Å. In the second Ag1+ site, Ag1+ is bonded to six S2- atoms to form AgS6 octahedra that share corners with two equivalent BiS6 octahedra, corners with four equivalent BiS5 square pyramids, edges with two equivalent AgS6 octahedra, and edges with six equivalent BiS5 square pyramids. The corner-sharing octahedral tilt angles are 53°. There are two shorter (2.53 Å) and four longer (2.91 Å) Ag–S bond lengths. There are four inequivalent Bi+2.88+ sites. In the first Bi+2.88+ site, Bi+2.88+ is bonded to six S2- atoms to form BiS6 octahedra that share corners with two equivalent AgS6 octahedra, corners with three BiS6 octahedra, edges with three equivalent AgS6 octahedra, and edges with seven BiS6 octahedra. The corner-sharing octahedra tilt angles range from 2–9°. There are a spread of Bi–S bond distances ranging from 2.70–3.01 Å. In the second Bi+2.88+ site, Bi+2.88+ is bonded to six S2- atoms to form BiS6 octahedra that share corners with two equivalent AgS6 octahedra, corners with four BiS6 octahedra, edges with five equivalent AgS6 octahedra, and edges with seven BiS6 octahedra. The corner-sharing octahedra tilt angles range from 0–5°. There are a spread of Bi–S bond distances ranging from 2.79–2.90 Å. In the third Bi+2.88+ site, Bi+2.88+ is bonded to six S2- atoms to form BiS6 octahedra that share a cornercorner with one AgS6 octahedra, corners with three BiS6 octahedra, corners with two equivalent BiS5 square pyramids, edges with two equivalent AgS6 octahedra, and edges with five BiS6 octahedra. The corner-sharing octahedra tilt angles range from 1–53°. There are a spread of Bi–S bond distances ranging from 2.66–3.09 Å. In the fourth Bi+2.88+ site, Bi+2.88+ is bonded to five S2- atoms to form BiS5 square pyramids that share corners with two equivalent AgS6 octahedra, corners with two equivalent BiS6 octahedra, edges with three equivalent AgS6 octahedra, and edges with four equivalent BiS5 square pyramids. The corner-sharing octahedra tilt angles range from 13–64°. There are a spread of Bi–S bond distances ranging from 2.63–2.87 Å. There are seven inequivalent S2- sites. In the first S2- site, S2- is bonded to two equivalent Ag1+ and four equivalent Bi+2.88+ atoms to form SAg2Bi4 octahedra that share corners with four equivalent SAg2Bi4 octahedra, corners with two equivalent SAgBi4 square pyramids, and edges with twelve SAg2Bi4 octahedra. The corner-sharing octahedral tilt angles are 3°. In the second S2- site, S2- is bonded to one Ag1+ and three Bi+2.88+ atoms to form distorted SAgBi3 tetrahedra that share a cornercorner with one SAg2Bi4 octahedra, corners with six SAg2Bi3 square pyramids, corners with three equivalent SAgBi3 tetrahedra, and edges with three equivalent SAg2Bi3 square pyramids. The corner-sharing octahedral tilt angles are 0°. In the third S2- site, S2- is bonded to two equivalent Ag1+ and four Bi+2.88+ atoms to form SAg2Bi4 octahedra that share corners with five SAg2Bi4 octahedra, edges with ten SAg2Bi4 octahedra, and edges with two equivalent SAgBi4 square pyramids. The corner-sharing octahedra tilt angles range from 1–6°. In the fourth S2- site, S2- is bonded to two equivalent Ag1+ and three equivalent Bi+2.88+ atoms to form distorted SAg2Bi3 square pyramids that share corners with two equivalent SAg2Bi3 square pyramids, corners with four equivalent SAgBi3 tetrahedra, edges with five equivalent SAg2Bi3 square pyramids, and edges with three equivalent SAgBi3 tetrahedra. In the fifth S2- site, S2- is bonded in a 3-coordinate geometry to three Bi+2.88+ atoms. In the sixth S2- site, S2- is bonded to two equivalent Ag1+ and four Bi+2.88+ atoms to form SAg2Bi4 octahedra that share corners with three equivalent SAg2Bi4 octahedra, corners with two equivalent SAgBi4 square pyramids, a cornercorner with one SAgBi3 tetrahedra, edges with seven SAg2Bi4 octahedra, and edges with three equivalent SAgBi4 square pyramids. The corner-sharing octahedra tilt angles range from 1–6°. In the seventh S2- site, S2- is bonded to one Ag1+ and four Bi+2.88+ atoms to form SAgBi4 square pyramids that share corners with three SAg2Bi4 octahedra, corners with two equivalent SAgBi3 tetrahedra, edges with five SAg2Bi4 octahedra, and edges with two equivalent SAgBi4 square pyramids. The corner-sharing octahedra tilt angles range from 1–7°.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Unraveling the Structural Sensitivity of Metal Catalysts in Ethylene Hydroformylation: Insights from Theory and Experiments

Here, in this study, we combined experimental and theoretical methods to investigate the structural sensitivity of metal catalysts in the ethylene hydroformylation reaction. Among Rh, Pt, Ir, Ni, Au, Ag, Pd, and Cu catalysts studied using experimental and theoretical methods, Rh showed the highest selectivity toward the C-C coupling product from CO and C 2 H 5 (i.e., C 2 H 5 CHO). The results from DFT and microkinetic simulations revealed that the activation energy barrier for C-C coupling is lowest on the Rh nanocluster, which explains the experimentally observed highest C 2 H 5 CHO selectivity on the Rh catalyst. Furthermore, DFT results demonstrated that the sites located on the flat surfaces of nanoparticles primarily promote the hydrogenation reaction, leading to the formation of undesired C 2 H 6 . In contrast, undercoordinated edge and corner sites of the nanocluster promote the C-C coupling reaction. Thus, our results illustrate that the selectivity toward C 3 oxygenates in ethylene hydroformylation reaction can be steered by tuning the size of Rh nanoparticles (the best-performing catalyst) to optimize the active (edge and corner) sites that preferentially promote the C-C coupling reaction.

58 GEOSCIENCES↗
DOE OSTI2020

Materials Data on GaAgGeS4 by Materials Project

AgGaGeS4 is Chalcostibite-derived structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are three inequivalent Ag1+ sites. In the first Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four S2- atoms. There are a spread of Ag–S bond distances ranging from 2.58–2.76 Å. In the second Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four S2- atoms. There are a spread of Ag–S bond distances ranging from 2.57–2.83 Å. In the third Ag1+ site, Ag1+ is bonded in a 4-coordinate geometry to four S2- atoms. There are a spread of Ag–S bond distances ranging from 2.58–2.72 Å. There are three inequivalent Ga3+ sites. In the first Ga3+ site, Ga3+ is bonded to four S2- atoms to form GaS4 tetrahedra that share a cornercorner with one GaS4 tetrahedra and corners with three GeS4 tetrahedra. There are a spread of Ga–S bond distances ranging from 2.27–2.34 Å. In the second Ga3+ site, Ga3+ is bonded to four S2- atoms to form GaS4 tetrahedra that share a cornercorner with one GaS4 tetrahedra and corners with three GeS4 tetrahedra. There are a spread of Ga–S bond distances ranging from 2.29–2.34 Å. In the third Ga3+ site, Ga3+ is bonded to four S2- atoms to form GaS4 tetrahedra that share corners with two GaS4 tetrahedra and corners with two equivalent GeS4 tetrahedra. There are a spread of Ga–S bond distances ranging from 2.27–2.32 Å. There are three inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to four S2- atoms to form GeS4 tetrahedra that share corners with two GaS4 tetrahedra and corners with two equivalent GeS4 tetrahedra. There are a spread of Ge–S bond distances ranging from 2.23–2.28 Å. In the second Ge4+ site, Ge4+ is bonded to four S2- atoms to form GeS4 tetrahedra that share corners with four GaS4 tetrahedra. There are a spread of Ge–S bond distances ranging from 2.23–2.28 Å. In the third Ge4+ site, Ge4+ is bonded to four S2- atoms to form GeS4 tetrahedra that share corners with two GaS4 tetrahedra and corners with two equivalent GeS4 tetrahedra. There are a spread of Ge–S bond distances ranging from 2.20–2.28 Å. There are twelve inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to one Ag1+ and two Ge4+ atoms. In the second S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to one Ag1+, one Ga3+, and one Ge4+ atom. In the third S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to one Ag1+, one Ga3+, and one Ge4+ atom. In the fourth S2- site, S2- is bonded in a water-like geometry to two Ge4+ atoms. In the fifth S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to one Ag1+, one Ga3+, and one Ge4+ atom. In the sixth S2- site, S2- is bonded in a 3-coordinate geometry to one Ag1+, one Ga3+, and one Ge4+ atom. In the seventh S2- site, S2- is bonded in a 3-coordinate geometry to one Ag1+ and two Ga3+ atoms. In the eighth S2- site, S2- is bonded in a water-like geometry to one Ga3+ and one Ge4+ atom. In the ninth S2- site, S2- is bonded in a trigonal non-coplanar geometry to one Ag1+, one Ga3+, and one Ge4+ atom. In the tenth S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to one Ag1+, one Ga3+, and one Ge4+ atom. In the eleventh S2- site, S2- is bonded to two Ag1+ and two Ga3+ atoms to form corner-sharing SGa2Ag2 tetrahedra. In the twelfth S2- site, S2- is bonded to two Ag1+, one Ga3+, and one Ge4+ atom to form corner-sharing SGaAg2Ge tetrahedra.

36 MATERIALS SCIENCE↗
NASA NTRS1996

RAINBOWS and CERAMBOWS: The Technologies of Pre-Stressed Piezo Actuators

Amplified mechanical displacement effects, similar to those observed in the recently reported Rainbow actuators, have also been found to exist in prestressed ceramic/metal composite structures coined as CERAMBOW's - an acronym for CERamic And Metal Biased Oxide Wafer. Mimicking the Rainbows in many ways, the intentionally created internal compressive and tensile stresses within the Cerambows are used to amplify their displacement properties via the combined effects of piezoelectric d31 strain and domain reorientation. They are fabricated from ferroelectric, piezoelectric or electrostrictive materials and metal substrates of significantly different thermal expansions which are largely responsible for the creation of the stress. Typical ceramics used in Cerambows are PZT, PLZT, PBZT, PSZT and PMN and some typical metal substrates are Al, Ag, Ni, brass, steel and Be/Cu foil. Shapes can vary from round disks to square plates and rectangular bars. Formed at an elevated temperature of approximately 250 C, the stresses on cooling to room temperature are generally sufficient to produce displacements as large as 0.125mm (5 mils) when activated unipolar and 0.25mm (10 mils) when operated bipolar at 450 volts in a dome mode. Comparing equal structures of a Cerambow with a Rainbow, the Cerambow was found to achieve approximately 70% of the displacement that would normally be obtained with a Rainbow. Although this difference in displacement is sufficient to prefer a Rainbow for many applications, there are some advantages for the Cerambow. Among these are (1) the processing temperatures are lower, (2) high lead-containing ceramics are not required and (3) in some instances the metal substrate is more convenient to interface with other elements of a device. However, the disadvantages include (1) lower displacement in the dome mode of operation, (2) the higher displacement saddle mode has not yet been demonstrated with a Cerambow and (3) the ceramic/metal bond interface is a possible failure area when operated for extended periods of time. The applications for Cerambows are considered to be similar to Rainbows, i.e., actuators, pumps, deflectors, vibrators, speakers, hydrophones, hydroprojectors, switches, etc.

Haertling, Gene H.↗
DOE OSTI2023

Development of local-power-free, remote α -particle detection using optical fibers

We demonstrate the application of fluorescence optical fiber coupled to a telecom grade fiber as a sensor for alpha particles using alpha-specific ZnS(Ag) scintillation materials whose wavelength is down-shifted into a low-loss region of the telecom grade fiber transmission band. Telecom-grade fiber optics offer a solution for sensing alpha radiation in deep repositories and cask storage for radioactive materials due to the stability of SiO 2 under normal environmental conditions and its relative radiation hardness at low radiation doses. Long-term nuclear waste storage facilities require sensors for the detection of leakage of radioactive materials that are maintenance-free, do not require power and can survive with no ‘wear out’ mechanisms for decades. By accomplishing the wavelength transformation, we maximize efficiencies in the detection of α-particles and signal transport and can detect alpha scintillation at distances on the order of >1 km with a sensor that is ~3% efficient and can be easily scaled as a sensor array. This paper describes the construction and testing of the sensor including manufacture of the controlled thickness films, verification of the wavelength shift from 450 to 620 nm and optimization of the sensitivity as a function of thickness. We also model the relative sensitivity of the film as a function of film thickness, and we demonstrate a signal-to-noise ratio of 10 at a range of greater than 1 km.

alpha particles↗
DOE OSTI2020

Materials Data on La6Sm2Co7AgO24 by Materials Project

Sm2La6Co7AgO24 is (Cubic) Perovskite-derived structured and crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Sm3+ is bonded to twelve O2- atoms to form SmO12 cuboctahedra that share corners with twelve LaO12 cuboctahedra, faces with two equivalent SmO12 cuboctahedra, faces with four equivalent LaO12 cuboctahedra, a faceface with one AgO6 octahedra, and faces with seven CoO6 octahedra. There are a spread of Sm–O bond distances ranging from 2.64–2.71 Å. There are two inequivalent La3+ sites. In the first La3+ site, La3+ is bonded to twelve O2- atoms to form LaO12 cuboctahedra that share corners with four equivalent SmO12 cuboctahedra, corners with eight LaO12 cuboctahedra, faces with two equivalent SmO12 cuboctahedra, faces with four LaO12 cuboctahedra, a faceface with one AgO6 octahedra, and faces with seven CoO6 octahedra. There are a spread of La–O bond distances ranging from 2.68–2.79 Å. In the second La3+ site, La3+ is bonded to twelve O2- atoms to form LaO12 cuboctahedra that share corners with four equivalent SmO12 cuboctahedra, corners with eight equivalent LaO12 cuboctahedra, faces with six LaO12 cuboctahedra, a faceface with one AgO6 octahedra, and faces with seven CoO6 octahedra. There are a spread of La–O bond distances ranging from 2.68–2.82 Å. There are five inequivalent Co+3.29+ sites. In the first Co+3.29+ site, Co+3.29+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with six CoO6 octahedra, faces with two equivalent SmO12 cuboctahedra, and faces with six LaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are a spread of Co–O bond distances ranging from 1.89–1.94 Å. In the second Co+3.29+ site, Co+3.29+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with six CoO6 octahedra, faces with two equivalent SmO12 cuboctahedra, and faces with six LaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are a spread of Co–O bond distances ranging from 1.90–1.92 Å. In the third Co+3.29+ site, Co+3.29+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with two equivalent AgO6 octahedra, corners with four CoO6 octahedra, faces with two equivalent SmO12 cuboctahedra, and faces with six LaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–4°. There are a spread of Co–O bond distances ranging from 1.81–1.94 Å. In the fourth Co+3.29+ site, Co+3.29+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with six CoO6 octahedra, faces with two equivalent SmO12 cuboctahedra, and faces with six LaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of Co–O bond distances ranging from 1.90–1.93 Å. In the fifth Co+3.29+ site, Co+3.29+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with two equivalent AgO6 octahedra, corners with four equivalent CoO6 octahedra, faces with two equivalent SmO12 cuboctahedra, and faces with six LaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–5°. There are a spread of Co–O bond distances ranging from 1.84–1.93 Å. Ag1+ is bonded to six O2- atoms to form AgO6 octahedra that share corners with six CoO6 octahedra, faces with two equivalent SmO12 cuboctahedra, and faces with six LaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 1–5°. There are two shorter (2.01 Å) and four longer (2.02 Å) Ag–O bond lengths. There are eleven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to four La3+ and two Co+3.29+ atoms. In the second O2- site, O2- is bonded in a distorted linear geometry to four La3+ and two Co+3.29+ atoms. In the third O2- site, O2- is bonded in a distorted linear geometry to four La3+, one Co+3.29+, and one Ag1+ atom. In the fourth O2- site, O2- is bonded in a distorted linear geometry to four La3+ and two Co+3.29+ atoms. In the fifth O2- site, O2- is bonded in a distorted linear geometry to two equivalent Sm3+, two equivalent La3+, and two Co+3.29+ atoms. In the sixth O2- site, O2- is bonded in a distorted linear geometry to two equivalent Sm3+, two equivalent La3+, and two Co+3.29+ atoms. In the seventh O2- site, O2- is bonded in a distorted linear geometry to two equivalent Sm3+, two equivalent La3+, one Co+3.29+, and one Ag1+ atom. In the eighth O2- site, O2- is bonded in a distorted linear geometry to two equivalent Sm3+, two equivalent La3+, and two Co+3.29+ atoms. In the ninth O2- site, O2- is bonded in a distorted linear geometry to one Sm3+, three La3+, and two Co+3.29+ atoms. In the tenth O2- site, O2- is bonded in a distorted linear geometry to one Sm3+, three La3+, and two Co+3.29+ atoms. In the eleventh O2- site, O2- is bonded in a distorted linear geometry to one Sm3+, three La3+, one Co+3.29+, and one Ag1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Microbial potentiometric sensor technology for real-time detecting and monitoring of toxic metals in aquatic matrices

Considering that toxic metals can affect metabolic processes in microorganisms adversely, it can be hypothesized that these metals in water matrices would induce a decrease in metabolic activity of the biofilm microorganisms populating the surface of a sensing electrode, which could be registered as a change in the open-circuit potential (OCP) generated by the biofilm microorganisms. The goal of this study was to test this hypothesis and demonstrate the underlying principle that microbial potentiometric sensor (MPS) technology could be used for long-term and real-time monitoring and detection of rapid changes in metal concentrations in realistic aquatic environments. To address the goal, four objective were addressed: (1) a batch reactor with three graphite-based MPS electrodes was fabricated; (2) a set of single-ion solutions and one multiple ion solution were prepared reflecting realistic concentrations of metals found in electroplating wastewaters; (3) the responses of the MPS to the simultaneous presence of multiple toxic metal ions in a single solution were measured; and (4) the changes of the MPS signals to the presence of individual metal ion solutions were examined. While the hypothesis was validated, the study also revealed that the MPS was sufficiently sensitive to not only detect, but also quantify, toxic metal ion concentrations in aqueous solutions. The coefficients of determination, which were R 2 > 0.995, and responsiveness of <1 μmol/L for some toxic metal cations, strongly support the performance of MPS technology in the echelons of expensive analytical tools capable detecting and measuring trace elements.The magnitude of the MPS response was toxic metal specific. When the molar concertation normalizes the inhibition portion of the signal area, the assessed sensitivity order was: Se>Cd>Pb>Ag>Ni> Zn. The study provides valuable information for enforcement agents, environmental professionals, and wastewater treatment operators, so toxic metal pollution and its detrimental impacts can be prevented and mitigated.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Size-tunable silver nanoparticle synthesis in glycerol driven by a low-pressure nonthermal plasma

Silver nanoparticles (NPs) are extensively used in electronic components, chemical sensors, and disinfection applications, in which many of their properties depend on particle size. However, control over silver NP size and morphology still remains a challenge for many synthesis techniques. Here, in this work, we demonstrate the surfactant-free synthesis of silver NPs using a low-pressure inductively coupled nonthermal argon plasma. Continuously forming droplets of silver nitrate (AgNO 3 ) precursor dissolved in glycerol are exposed to the plasma, with the droplet residence time being determined by the precursor flow rate. Glycerol has rarely been studied in plasma-liquid interactions but shows favorable properties for controlled NP synthesis at low pressure. We show that the droplet residence time and plasma power have strong influence on NP properties, and that improved size control and particle monodispersity can be achieved by pulsed power operation. Silver NPs had mean diameters of 20 nm with geometric standard deviations of 1.6 under continuous wave operation, which decreased to 6 nm mean and 1.3 geometric standard deviation for pulsed power operation at 100 Hz and 20% duty cycle. We propose that solvated electrons from the plasma and vacuum ultraviolet (VUV) radiation induced electrons produced in glycerol are the main reducing agents of Ag + , the precursor for NPs, while no significant change of chemical composition of the glycerol solvent was detected.

36 MATERIALS SCIENCE↗