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At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Low fractional volume superconductivity in single crystals of Pr{sub 4}Ni{sub 3}O{sub 10} under pressure

Magnetotransport measurements of P⁢r4⁢N⁢i3⁢O10 single crystals performed under externally applied pressures up to 73 GPa in diamond anvil cells with either KBr or Nujol oil as pressure media yield signatures of superconductivity with a maximum onset temperature of approximately 31 K. True zero resistance was not observed, consistent with a nonpercolating superconducting volume fraction. Magnetization measurements provided corroborating evidence of superconductivity, with a pressure-dependent diamagnetic signal occurring below the onset temperature, and an estimate from the absolute value of the susceptibility suggests a superconducting volume fraction on the order of 10%. We observe sample to sample variations in the magnitude and pressure dependence of 𝑇𝑐 as well as a dependence on the configuration of electrical contacts on a given sample. Possible causes of this behavior may be significant inhomogeneities in the pressure and/or damage to the samples induced by the pressure media as well as inhomogeneities in the crystals themselves. The results imply that our as-grown P⁢r4⁢N⁢i3⁢O10 single crystals are not bulk superconductors but that there is a minority structure present within the crystals that is indeed superconductin

Chen, Xinglong↗
DOE OSTI2020

Phase diagram of infinite layer praseodymium nickelate Pr 1– x Sr x NiO 2 thin films

In this paper, we report the phase diagram of infinite layer Pr 1-x Sr x NiO 2 thin films synthesized via topotactic reduction from the perovskite precursor phase using CaH 2 . Based on the electrical transport properties, we find a doping-dependent superconducting dome extending between x = 0.12 and 0.28, with a maximum superconducting transition temperature T c of 14 K at x = 0.18, bounded by weakly insulating behavior on both sides. In contrast to the narrower dome observed in Nd 1–x Sr x NiO 2 , a local T c suppression near x = 0.2 was not observed for the Pr 1-x Sr x NiO 2 system. Normal state Hall effect measurements indicate mixed carrier contributions of both electrons and holes, and show a sign change in the Hall coefficient as functions of temperature and x, quite similar to that in Nd 1-x Sr x NiO 2 . Also similar is the observation of a minimum in the normal state resistivity associated with the superconducting compositions. These findings indicate an infinite layer nickelate phase diagram that is relatively insensitive to the rare-earth element, but suggest that disorder arising from the variations of the ionic radii on the rare-earth site affects the superconducting dome.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Physical properties of 𝑅⁢ Co 2 ⁢Al 8 single crystals (𝑅 = La, Ce, Pr, Nd, and Sm) : An emerging structure-type for anisotropic Kondo-lattice studies

Systematic investigations of rare-earth (𝑅)-based intermetallic materials are a leading strategy to reveal the underlying mechanisms governing a range of physical phenomena, such as the formation of a Kondo lattice and competing electronic and magnetic anisotropies. Here, in this work, the magnetic, thermal, and transport properties of 𝑅⁢Co 2 ⁢Al 8 (𝑅 = La, Ce, Pr, Nd, and Sm) single crystals are presented. LaCo 2 ⁢Al 8 is characterized as a Pauli paramagnet, and transport measurements, with the current along and perpendicular to the orthorhombic 𝑐-axis (𝜌 𝑐 and 𝜌 𝑎⁢𝑏 , respectively), reveal a clear electronic anisotropy, with 𝜌 𝑎⁢𝑏 ⁢≈ (4 –7)⁢𝜌 𝑐 at 300K . We show that CeCo 2 ⁢Al 8 is a Kondo lattice for which the Kondo coherence temperature 𝑇$^*_K$, deduced from broad maximums in 𝜌 𝑐 and 𝜌 𝑎⁢𝑏 at ≈ 68 and 46 K, respectively, is also anisotropic. This finding is related to a possible underlying anisotropy of the Kondo coupling in CeCo 2⁢ Al 8 . The Pr- and Nd-based materials present strong easy-axis anisotropy (𝑐-axis) and antiferromagnetic (AFM) orders below 𝑇 = 4.84 and 8.1K , respectively. Metamagnetic transitions from this AFM to a spin-polarized paramagnetic phase state are investigated by isothermal magnetization measurements. The Sm-based compound is also an easy-axis AFM with a transition at 𝑇 = 21.6K .

Garcia, Fernando A. [Ames Laboratory (AMES), Ames,↗
DOE OSTI2025

CO 2 Electrolysis Using Metal-Supported Solid Oxide Cells with Infiltrated Pr 0.5 Sr 0.4 Mn 0.2 Fe 0.8 O 3-$δ$ Catalyst

Electrochemical conversion of CO 2 to CO is demonstrated with symmetric-structured metal supported solid oxide cells (MS-SOC). Perovskite Pr 0.5 Sr 0.4 Mn 0.2 Fe 0.8 O 3-δ (PSMF) and Pr 6 O 11 catalysts were infiltrated into the MS-SOC cathode and anode, using 3 cycles with firing at 850 °C and 8 cycles with firing at 800 °C, respectively. Upon reduction during operation, the perovskite PSMF was transformed to Ruddlesden–Popper structure with a highly efficient electrocatalytic activity. The impact of operating temperature (600–800 °C) and overpotential (0–1.8 V) on the CO 2 conversion was investigated. The highest CO 2 conversion of 57.2% was achieved at 750 °C and 1.8 V. During extended operation for 150 h at 750 °C and 1.2 V, a cell demonstrated relatively stable performance, with initial current density of 535 mA cm -2 and CO 2 conversion of 23%. Degradation mechanisms were studied by posttest characterization.

25 ENERGY STORAGE↗
DOE OSTI2024

Comparing Designed Training Sets to Optimize Multivariate Regression Models for Pr, Nd, and Nitric Acid Using Spectrophotometry

Chemometric regression models were developed for the quantification of praseodymium (Pr, 0–1000 µg/mL), neodymium (Nd, 0–1000 µg/mL), and nitric acid (HNO 3 , 0.1–5 M) using spectrophotometry. Designed calibration sets were composed of 20 samples each: 10 model points and 10 lack-of-fit (LOF) points. The D-optimal designs effectively minimized the number of samples required to build models, and each design resulted in similar prediction performance, suggesting that statistical design of experiments can provide a reliable framework for selecting training set samples in three-variable systems. Partial least squares regression (PLSR) models were validated against a one-factor-at-a-time validation set composed of 125 samples (three variables, five levels). The top PLS-1 models resulted in average percent root mean square error of prediction error values of 3.5%, 1.7%, and 1.2% for Pr(III), Nd(III), and HNO 3 , respectively. Power set augmentations of the model and LOF samples were investigated to optimize the number of training set samples. PLSR models built using just required model points (10) had similar predictive capabilities as models including the LOF points (20) but with fewer samples. The number of validation samples was also varied systematically to learn how many samples are needed to validate regression models. This work addresses long-standing questions in the field of chemometrics to help make this approach amenable to the near-real-time quantification of hazardous species in remote settings.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

SST-TG-P50F4R3200: Decaying Stably-Stratified Turbulence (SST), Initialized Using Taylor-Green Vortices (TG) at Prandtl Number Pr=50, Froude Number Fr=4, Reynolds Number Re=3200

This dataset comprises direct numerical simulations (DNS) of decaying stably-stratified turbulence influenced by a linear background density gradient, initialized using an array of Taylor-Green vortices, extending the Pr=1 simulations performed in [Riley and de Bruyn Kops (2003)](https://doi.org/10.1063/1.1578077). The initial Prandtl, Froude, and Reynolds numbers are (Pr, Fr, Re) = (50, 4, 3200). A total of 1,680 snapshots are recorded at uniform time intervals, each with a spatial resolution of 3584x3584x1792 grid points. Four flow variables are associated with each snapshot: the three velocity components (u,v,w) and the perturbed density field (rho) away from the background gradient. All fields are stored in binary format (32-bit little-endian), each with a size of 85.8 GB, yielding a total dataset size of 577 TB. Further details are referenced in the attached README file, and a current list of publications and associated analysis tools are provided at https://stratified-turbulence.github.io/web/.

42 ENGINEERING↗
DOE OSTI2025

SST-TG-P7F4R3200: Decaying Stably-Stratified Turbulence (SST), Initialized Using Taylor-Green Vortices (TG) at Prandtl Number Pr=7, Froude Number Fr=4, Reynolds Number Re=3200

This dataset comprises direct numerical simulations (DNS) of decaying stably-stratified turbulence influenced by a linear background density gradient, initialized using an array of Taylor-Green vortices, extending the Pr=1 simulations performed in [Riley and de Bruyn Kops (2003)](https://doi.org/10.1063/1.1578077). The initial Prandtl, Froude, and Reynolds numbers are (Pr, Fr, Re) = (7, 4, 3200). A total of 15,250 snapshots are recorded at uniform time intervals, each with a spatial resolution of 1280x1280x640 grid points. Four flow variables are associated with each snapshot: the three velocity components (u,v,w) and the perturbed density field (rho) away from the background gradient. All fields are stored in binary format (32-bit little-endian), each with a size of 4 GB, yielding a total dataset size of 244 TB. Further details are referenced in the attached README file, and a current list of publications and associated analysis tools are provided at https://stratified-turbulence.github.io/web/.

42 ENGINEERING↗
DOE OSTI2025

AmeriFlux FLUXNET-1F PR-xLA NEON Lajas Experimental Station (LAJA)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site PR-xLA NEON Lajas Experimental Station (LAJA). This is the FLUXNET version of the carbon flux data for the site PR-xLA NEON Lajas Experimental Station (LAJA) produced by applying the standard ONEFlux (1F) software. Site Description - The NEON Lajas Experimental Station (LAJA) site is located on the southwest corner of the main island of Puerto Rico in a experimental range. This is a grassland site that is periodically grazed by cattle.

Network), NEON (National Ecological Observatory [N↗
DOE OSTI2026

AmeriFlux FLUXNET-1F PR-xGU NEON Guanica Forest (GUAN)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site PR-xGU NEON Guanica Forest (GUAN). This is the FLUXNET version of the carbon flux data for the site PR-xGU NEON Guanica Forest (GUAN) produced by applying the standard ONEFlux (1F) software. Site Description - The Guanica Forest (GUAN) site is located on the southwest corner of the main island of Puerto Rico in a protected forest with primary phenological species of Gymnanthes lucida, Pisonia albida, and Bursera simaruba. The mean canopy height is approximately 10 m.

Network), NEON (National Ecological Observatory [N↗
DOE OSTI2020

Materials Data on Pr(ZnP)3 by Materials Project

PrZn3P3 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Pr3+ is bonded to six equivalent P3- atoms to form PrP6 octahedra that share corners with six equivalent ZnP4 tetrahedra, edges with six equivalent PrP6 octahedra, and edges with six equivalent ZnP4 tetrahedra. All Pr–P bond lengths are 2.95 Å. There are two inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded in a trigonal planar geometry to three equivalent P3- atoms. All Zn–P bond lengths are 2.35 Å. In the second Zn2+ site, Zn2+ is bonded to four P3- atoms to form ZnP4 tetrahedra that share corners with three equivalent PrP6 octahedra, corners with seven equivalent ZnP4 tetrahedra, and edges with three equivalent PrP6 octahedra. The corner-sharing octahedral tilt angles are 18°. There are one shorter (2.42 Å) and three longer (2.49 Å) Zn–P bond lengths. There are two inequivalent P3- sites. In the first P3- site, P3- is bonded to five Zn2+ atoms to form PZn5 trigonal bipyramids that share corners with six equivalent PPr3Zn3 octahedra and corners with six equivalent PZn5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 70°. In the second P3- site, P3- is bonded to three equivalent Pr3+ and three equivalent Zn2+ atoms to form distorted PPr3Zn3 octahedra that share corners with three equivalent PPr3Zn3 octahedra, corners with three equivalent PZn5 trigonal bipyramids, and edges with nine equivalent PPr3Zn3 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(CdP)3 by Materials Project

PrCd3P3 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Pr3+ is bonded to six equivalent P3- atoms to form PrP6 octahedra that share corners with six equivalent CdP4 tetrahedra, edges with six equivalent PrP6 octahedra, and edges with six equivalent CdP4 tetrahedra. All Pr–P bond lengths are 2.99 Å. There are two inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded in a trigonal planar geometry to three equivalent P3- atoms. All Cd–P bond lengths are 2.50 Å. In the second Cd2+ site, Cd2+ is bonded to four P3- atoms to form CdP4 tetrahedra that share corners with three equivalent PrP6 octahedra, corners with seven equivalent CdP4 tetrahedra, and edges with three equivalent PrP6 octahedra. The corner-sharing octahedral tilt angles are 11°. There are one shorter (2.62 Å) and three longer (2.70 Å) Cd–P bond lengths. There are two inequivalent P3- sites. In the first P3- site, P3- is bonded to five Cd2+ atoms to form PCd5 trigonal bipyramids that share corners with six equivalent PPr3Cd3 octahedra and corners with six equivalent PCd5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 67°. In the second P3- site, P3- is bonded to three equivalent Pr3+ and three equivalent Cd2+ atoms to form PPr3Cd3 octahedra that share corners with three equivalent PPr3Cd3 octahedra, corners with three equivalent PCd5 trigonal bipyramids, and edges with nine equivalent PPr3Cd3 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(BC)2 by Materials Project

PrB2C2 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. Pr4+ is bonded in a body-centered cubic geometry to eight equivalent C2- atoms. All Pr–C bond lengths are 2.81 Å. B is bonded in a distorted trigonal planar geometry to three equivalent C2- atoms. There is one shorter (1.54 Å) and two longer (1.62 Å) B–C bond length. C2- is bonded in a 3-coordinate geometry to four equivalent Pr4+ and three equivalent B atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(FeP3)4 by Materials Project

PrFe4P12 crystallizes in the cubic Im-3 space group. The structure is three-dimensional. Pr3+ is bonded to twelve equivalent P1- atoms to form PrP12 cuboctahedra that share faces with eight equivalent FeP6 octahedra. All Pr–P bond lengths are 3.01 Å. Fe+2.25+ is bonded to six equivalent P1- atoms to form FeP6 octahedra that share corners with six equivalent FeP6 octahedra and faces with two equivalent PrP12 cuboctahedra. The corner-sharing octahedral tilt angles are 59°. All Fe–P bond lengths are 2.25 Å. P1- is bonded in a 2-coordinate geometry to one Pr3+, two equivalent Fe+2.25+, and two equivalent P1- atoms. There are one shorter (2.29 Å) and one longer (2.37 Å) P–P bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(SiAu)2 by Materials Project

PrAu2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Pr3+ is bonded to eight equivalent Si4- atoms to form PrSi8 hexagonal bipyramids that share corners with sixteen equivalent AuSi4 tetrahedra, edges with four equivalent PrSi8 hexagonal bipyramids, edges with eight equivalent AuSi4 tetrahedra, and faces with four equivalent PrSi8 hexagonal bipyramids. All Pr–Si bond lengths are 3.29 Å. Au+2.50+ is bonded to four equivalent Si4- atoms to form AuSi4 tetrahedra that share corners with eight equivalent PrSi8 hexagonal bipyramids, corners with four equivalent AuSi4 tetrahedra, edges with four equivalent PrSi8 hexagonal bipyramids, and edges with four equivalent AuSi4 tetrahedra. All Au–Si bond lengths are 2.59 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Pr3+, four equivalent Au+2.50+, and one Si4- atom. The Si–Si bond length is 2.36 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(SiAg)2 by Materials Project

PrAg2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Pr4+ is bonded to eight equivalent Si4- atoms to form PrSi8 hexagonal bipyramids that share corners with sixteen equivalent AgSi4 tetrahedra, edges with four equivalent PrSi8 hexagonal bipyramids, edges with eight equivalent AgSi4 tetrahedra, and faces with four equivalent PrSi8 hexagonal bipyramids. All Pr–Si bond lengths are 3.24 Å. Ag2+ is bonded to four equivalent Si4- atoms to form AgSi4 tetrahedra that share corners with eight equivalent PrSi8 hexagonal bipyramids, corners with four equivalent AgSi4 tetrahedra, edges with four equivalent PrSi8 hexagonal bipyramids, and edges with four equivalent AgSi4 tetrahedra. All Ag–Si bond lengths are 2.62 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Pr4+, four equivalent Ag2+, and one Si4- atom. The Si–Si bond length is 2.34 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(SiPd)2 by Materials Project

PrPd2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Pr4+ is bonded to eight equivalent Si4- atoms to form PrSi8 hexagonal bipyramids that share corners with sixteen equivalent PdSi4 tetrahedra, edges with four equivalent PrSi8 hexagonal bipyramids, edges with eight equivalent PdSi4 tetrahedra, and faces with four equivalent PrSi8 hexagonal bipyramids. All Pr–Si bond lengths are 3.24 Å. Pd2+ is bonded to four equivalent Si4- atoms to form PdSi4 tetrahedra that share corners with eight equivalent PrSi8 hexagonal bipyramids, corners with four equivalent PdSi4 tetrahedra, edges with four equivalent PrSi8 hexagonal bipyramids, and edges with four equivalent PdSi4 tetrahedra. All Pd–Si bond lengths are 2.50 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Pr4+, four equivalent Pd2+, and one Si4- atom. The Si–Si bond length is 2.39 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(CuSi)2 by Materials Project

PrCu2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Pr4+ is bonded in a distorted body-centered cubic geometry to eight equivalent Si4- atoms. All Pr–Si bond lengths are 3.15 Å. Cu2+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing CuSi4 tetrahedra. All Cu–Si bond lengths are 2.42 Å. Si4- is bonded in a 9-coordinate geometry to four equivalent Pr4+, four equivalent Cu2+, and one Si4- atom. The Si–Si bond length is 2.43 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(CoB)2 by Materials Project

PrCo2B2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Pr3+ is bonded in a body-centered cubic geometry to eight equivalent B3- atoms. All Pr–B bond lengths are 3.03 Å. Co+1.50+ is bonded to four equivalent B3- atoms to form a mixture of distorted edge and corner-sharing CoB4 tetrahedra. All Co–B bond lengths are 1.99 Å. B3- is bonded in a 4-coordinate geometry to four equivalent Pr3+ and four equivalent Co+1.50+ atoms.

36 MATERIALS SCIENCE↗