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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on FeH2Cl5O3 by Materials Project

FeH2O3Cl5 is High Pressure (4-7GPa) Tellurium structured and crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four FeH2O3Cl5 clusters. Fe is bonded in a 6-coordinate geometry to one O and five Cl atoms. The Fe–O bond length is 1.92 Å. There are a spread of Fe–Cl bond distances ranging from 2.29–2.58 Å. H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. There are two inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one Fe atom. In the second O site, O is bonded in a single-bond geometry to one H and one Cl atom. The O–Cl bond length is 2.30 Å. There are four inequivalent Cl sites. In the first Cl site, Cl is bonded in a single-bond geometry to one Fe atom. In the second Cl site, Cl is bonded in a distorted trigonal non-coplanar geometry to one Fe and two equivalent O atoms. In the third Cl site, Cl is bonded in a single-bond geometry to one Fe atom. In the fourth Cl site, Cl is bonded in a single-bond geometry to one Fe atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiH20C8ClO4 by Materials Project

LiC8H20O4Cl is High Pressure Cadmuum Telluride-derived structured and crystallizes in the monoclinic C2/c space group. The structure is zero-dimensional and consists of four LiC8H20O4Cl clusters. Li1+ is bonded to four O2- and one Cl1- atom to form LiClO4 trigonal bipyramids that share corners with four CH3O tetrahedra. There are two shorter (2.12 Å) and two longer (2.14 Å) Li–O bond lengths. The Li–Cl bond length is 2.42 Å. There are four inequivalent C+1.50- sites. In the first C+1.50- site, C+1.50- is bonded to three H1+ and one O2- atom to form CH3O tetrahedra that share a cornercorner with one LiClO4 trigonal bipyramid. All C–H bond lengths are 1.10 Å. The C–O bond length is 1.43 Å. In the second C+1.50- site, C+1.50- is bonded in a distorted trigonal non-coplanar geometry to two H1+ and one O2- atom. There is one shorter (1.10 Å) and one longer (1.11 Å) C–H bond length. The C–O bond length is 1.44 Å. In the third C+1.50- site, C+1.50- is bonded in a distorted trigonal non-coplanar geometry to two H1+ and one O2- atom. Both C–H bond lengths are 1.11 Å. The C–O bond length is 1.44 Å. In the fourth C+1.50- site, C+1.50- is bonded to three H1+ and one O2- atom to form CH3O tetrahedra that share a cornercorner with one LiClO4 trigonal bipyramid. All C–H bond lengths are 1.10 Å. The C–O bond length is 1.44 Å. There are ten inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C+1.50- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C+1.50- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one C+1.50- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one C+1.50- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one C+1.50- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one C+1.50- atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one C+1.50- atom. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one C+1.50- atom. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to one C+1.50- atom. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one C+1.50- atom. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Li1+ and two C+1.50- atoms. In the second O2- site, O2- is bonded in a trigonal non-coplanar geometry to one Li1+ and two C+1.50- atoms. Cl1- is bonded in a single-bond geometry to one Li1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CrH14N4Cl3O by Materials Project

CrN4H14OCl3 is High Pressure (4-7GPa) Tellurium structured and crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four CrN4H14OCl3 clusters. Cr3+ is bonded in an octahedral geometry to four N3-, one O2-, and one Cl1- atom. There are one shorter (2.09 Å) and three longer (2.10 Å) Cr–N bond lengths. The Cr–O bond length is 2.08 Å. The Cr–Cl bond length is 2.35 Å. There are three inequivalent N3- sites. In the first N3- site, N3- is bonded in a distorted trigonal non-coplanar geometry to one Cr3+ and three H1+ atoms. There is one shorter (1.02 Å) and two longer (1.03 Å) N–H bond length. In the second N3- site, N3- is bonded in a distorted trigonal non-coplanar geometry to one Cr3+ and three H1+ atoms. There is one shorter (1.02 Å) and two longer (1.03 Å) N–H bond length. In the third N3- site, N3- is bonded in a distorted trigonal non-coplanar geometry to one Cr3+ and three H1+ atoms. There is one shorter (1.02 Å) and two longer (1.03 Å) N–H bond length. There are eight inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- and one Cl1- atom. The H–O bond length is 1.00 Å. The H–Cl bond length is 2.10 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. O2- is bonded in a distorted trigonal non-coplanar geometry to one Cr3+ and two equivalent H1+ atoms. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Cr3+ atom. In the second Cl1- site, Cl1- is bonded in a distorted single-bond geometry to one H1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CoBr3N5 by Materials Project

CoN5Br3 is High Pressure (4-7GPa) Tellurium structured and crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four CoN5Br3 clusters. Co4+ is bonded in a 2-coordinate geometry to five N+1.40- atoms. There are a spread of Co–N bond distances ranging from 1.60–2.22 Å. There are four inequivalent N+1.40- sites. In the first N+1.40- site, N+1.40- is bonded in a T-shaped geometry to one Co4+ and two equivalent N+1.40- atoms. Both N–N bond lengths are 1.20 Å. In the second N+1.40- site, N+1.40- is bonded in a distorted single-bond geometry to one Co4+ and one Br1+ atom. The N–Br bond length is 1.81 Å. In the third N+1.40- site, N+1.40- is bonded in a distorted single-bond geometry to one Co4+ and two equivalent Br1+ atoms. Both N–Br bond lengths are 1.90 Å. In the fourth N+1.40- site, N+1.40- is bonded in a 2-coordinate geometry to one Co4+ and one N+1.40- atom. There are two inequivalent Br1+ sites. In the first Br1+ site, Br1+ is bonded in a single-bond geometry to one N+1.40- atom. In the second Br1+ site, Br1+ is bonded in a single-bond geometry to one N+1.40- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CoN5Cl3 by Materials Project

CoN5Cl3 is High Pressure (4-7GPa) Tellurium structured and crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four CoN5Cl3 clusters. Co2+ is bonded in a distorted bent 120 degrees geometry to five N+0.20+ atoms. There are a spread of Co–N bond distances ranging from 1.58–1.95 Å. There are four inequivalent N+0.20+ sites. In the first N+0.20+ site, N+0.20+ is bonded in a single-bond geometry to one Co2+ and two equivalent Cl1- atoms. Both N–Cl bond lengths are 2.42 Å. In the second N+0.20+ site, N+0.20+ is bonded in a single-bond geometry to one Co2+ atom. In the third N+0.20+ site, N+0.20+ is bonded in a water-like geometry to one Co2+ and one Cl1- atom. The N–Cl bond length is 1.68 Å. In the fourth N+0.20+ site, N+0.20+ is bonded in a distorted bent 120 degrees geometry to one Co2+ and one Cl1- atom. The N–Cl bond length is 1.67 Å. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one N+0.20+ atom. In the second Cl1- site, Cl1- is bonded in a distorted single-bond geometry to two N+0.20+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on OF2 by Materials Project

OF2 is High Pressure (4-7GPa) Tellurium structured and crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four oxygen difluoride molecules. O is bonded in a water-like geometry to two equivalent F atoms. Both O–F bond lengths are 1.43 Å. F is bonded in a single-bond geometry to one O atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HgBrCl by Materials Project

HgClBr is High Pressure (4-7GPa) Tellurium structured and crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four bromo(chloro)mercury molecules. Hg2+ is bonded in a linear geometry to one Br1- and one Cl1- atom. The Hg–Br bond length is 2.44 Å. The Hg–Cl bond length is 2.33 Å. Br1- is bonded in a single-bond geometry to one Hg2+ atom. Cl1- is bonded in a single-bond geometry to one Hg2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AlTeH6C2Cl3 by Materials Project

AlC2H6TeCl3 is High Pressure (4-7GPa) Tellurium structured and crystallizes in the orthorhombic Pbcm space group. The structure is zero-dimensional and consists of four AlC2H6TeCl3 clusters. Al3+ is bonded in a distorted tetrahedral geometry to one Te2- and three Cl1- atoms. The Al–Te bond length is 2.75 Å. There are two shorter (2.14 Å) and one longer (2.15 Å) Al–Cl bond lengths. C2- is bonded in a distorted trigonal non-coplanar geometry to three H1+ and one Te2- atom. There is one shorter (1.09 Å) and two longer (1.10 Å) C–H bond length. The C–Te bond length is 2.15 Å. There are three inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one C2- atom. Te2- is bonded in a 3-coordinate geometry to one Al3+ and two equivalent C2- atoms. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Al3+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Al3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CoBr3N5 by Materials Project

CoN5Br3 is High Pressure (4-7GPa) Tellurium structured and crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four CoN5Br3 clusters. Co4+ is bonded in a 4-coordinate geometry to five N+1.40- atoms. There are a spread of Co–N bond distances ranging from 1.56–2.15 Å. There are four inequivalent N+1.40- sites. In the first N+1.40- site, N+1.40- is bonded in a 3-coordinate geometry to one Co4+, two equivalent N+1.40-, and one Br1+ atom. Both N–N bond lengths are 1.28 Å. The N–Br bond length is 2.01 Å. In the second N+1.40- site, N+1.40- is bonded in a single-bond geometry to one Co4+ atom. In the third N+1.40- site, N+1.40- is bonded in a distorted single-bond geometry to one Co4+ and two equivalent Br1+ atoms. Both N–Br bond lengths are 1.89 Å. In the fourth N+1.40- site, N+1.40- is bonded in a distorted L-shaped geometry to one Co4+ and one N+1.40- atom. There are two inequivalent Br1+ sites. In the first Br1+ site, Br1+ is bonded in a single-bond geometry to one N+1.40- atom. In the second Br1+ site, Br1+ is bonded in a single-bond geometry to one N+1.40- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2021

A virtual element generalization on polygonal meshes of the Scott-Vogelius finite element method for the 2-D Stokes problem

The virtual element method (VEM) is a Galerkin approximation method that extends the finite element method to polytopal meshes. In this paper, we present a conforming formulation that generalizes the Scott-Vogelius finite element method (FEM) for the numerical approximation of the Stokes problem to polygonal meshes in the framework of the virtual element method. In particular, we consider a straightforward application of the virtual element approximation space for scalar elliptic problems to the vector case and approximate the pressure variable through discontinuous polynomials. We assess the effectiveness of the numerical approximation by investigating the convergence on a manufactured solution problem and a set of representative polygonal meshes. We numerically show that this formulation is convergent with optimal convergence rates except for the lowest-order case on triangular and square meshes where the method coincides with the P 1 - P 0 Scott-Vogelius scheme, which is well-known to be unstable.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2022

Implementation and Results of Extended-MHD Post-processing of xRAGE Simulations

Magnetic fields are known to affect the evolution of conducting fluids via the J× B force, where J is the current density and B is the magnetic field. Typically, J× B in high energy density plasmas (HEDP) systems is considered small compared to the plasma pressure gradients. However, many experiments lie in a part of the parameter space where the plasma is indirectly affected via magnetization of the heat flux and charged particle transport. This is true even for initially unmagnetized plasmas, since misaligned density and temperature gradients can self-generate the so-called Biermann magnetic fields.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

AI-Enabled Robotic NDE for Structural Damage Assessment and Repair

The aim of this paper is to develop the concept and a prototype of an intelligent mobile robotic platform that is integrated with nondestructive evaluation (NDE) capabilities for autonomous live inspection and repair. In many industrial environments, such as the application of power plant boiler inspection, human inspectors often have to perform hazardous and challenging tasks. There is a significant chance of injury, considering the confined spaces and limited visibility of the inspection environment and hazards such as pressurization and improper water levels. In order to provide a solution to eliminate these dangers, the concept of a new robotic system was developed and prototyped that is capable of autonomously sweeping the region to be inspected. The robot design contains systematic integration of components from robotics, NDE, and artificial intelligence (AI). A magnetic track system is used to navigate over the vertical steel structures required for examination. While moving across the inspection area, the robot uses an NDE sensor to acquire data for inspection and repair. This paper presents a design of a portable NDE scanning system based on eddy current array probes, which can be customized and installed on various mobile robot platforms. Machine learning methods are applied for semantic segmentation that will simultaneously localize and recognize defects without the need of human intervention. Experiments were conducted that show the NDE and repair capabilities of the system. Improvements in human safety and structural damage prevention, as well as lowering the overall costs of maintenance, are possible through the implementation of this robotic NDE system.

Materials Science↗
DOE OSTI2021

A virtual element generalization on polygonal meshes of the Scott-Vogelius finite element method for the 2-D Stokes problem

The Virtual Element Method (VEM) is a Galerkin approximation method that extends the Finite Element Method (FEM) to polytopal meshes. In this paper, we present a conforming formulation that generalizes the Scott-Vogelius finite element method for the numerical approximation of the Stokes problem to polygonal meshes in the framework of the virtual element method. In particular, we consider a straightforward application of the virtual element approximation space for scalar elliptic problems to the vector case and approximate the pressure variable through discontinuous polynomials. We assess the effectiveness of the numerical approximation by investigating the convergence on a manufactured solution problem and a set of representative polygonal meshes. Finally, we numerically show that this formulation is convergent with optimal convergence rates except for the lowest-order case on triangular meshes, where the method coincides with the $\mathbb{P}_1$ – $\mathbb{P}_0$ Scott-Vogelius scheme, and on square meshes, which are situations that are well-known to be unstable.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2023

Expandable systems for space

Systems for insulating a space vehicle or space borne container from an external environment as well as cryogens from heat sources. Such systems also protect the vehicle from the high dynamic pressures, the high heat loads encountered in atmospheric flight, and provide storage capability that strongly limits, or effectively eliminates, cryogenic boil-off losses once in space. Such systems include an expandable structure having a plurality of contiguously adjacent expandable layers. The layers are connected by a plurality of tension connectors between successive layers. For launch and flight the layers can be restrained in a collapsed position. Whereupon exiting a free stream environment, the layers are expanded where they can lock into place or otherwise remain in an expanded state. The expansion creates separation between the layers with minimal conduction paths providing near theoretically perfect multi-layer insulation and extremely effective debris protection.

de Jong, Maxim↗
DOE OSTI2022

Generalized quasiharmonic approximation via space group irreducible derivatives

The quasiharmonic approximation (QHA) is the simplest nontrivial approximation for interacting phonons under constant pressure, bringing the effects of anharmonicity into temperature-dependent observables. Nonetheless, the QHA is often implemented with additional approximations due to the complexity of computing phonons under arbitrary strains, and the generalized QHA, which employs constant stress boundary conditions, has not been completely developed. In this work we formulate the generalized QHA, providing a practical algorithm for computing the strain state and other observables as a function of temperature and true stress. We circumvent the complexity of computing phonons under arbitrary strains by employing irreducible second-order displacement derivatives of the Born-Oppenheimer potential and their strain dependence, which are efficiently and precisely computed using the lone irreducible derivative approach. We formulate two complementary strain parametrizations: a discretized strain grid interpolation and a Taylor series expansion in symmetrized strain. We illustrate our approach by evaluating the temperature and pressure dependence of select elastic constants and the thermal expansion in thoria (ThO 2 ) using density functional theory with three exchange-correlation functionals. The QHA results are compared to our measurements of the elastic constant tensor using time-domain Brillouin scattering and inelastic neutron scattering. Our irreducible derivative approach simplifies the implementation of the generalized QHA, which will facilitate reproducible, data-driven applications.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Revealing pressure-driven structural transitions in the hybrid improper ferroelectric Sr 3 Sn 2 O 7

In this work, we combine diamond anvil cell techniques and synchrotron-based infrared spectroscopy with a detailed symmetry analysis and lattice dynamics calculations to uncover a series of pressure induced structural phase transitions in the hybrid improper ferroelectric Sr 3 Sn 2 O 7 . The microscopic character of each high pressure phase is determined by comparing the measured spectrum with the predicted vibrational patterns of several related but distinct candidate space groups. Our analysis reveals a sequence of compression-induced transitions from A2 1 am ↔ Pnab ↔ Acaa ↔ I4/mmm at room temperature. Remarkably, this space group progression matches the sequence of temperature-dependent structural transitions observed in Sr 3 Sn 2 O 7 between 77 and 1000 K. Other hybrid improper ferroelectrics display a similar set of transitions, suggesting that pressure and probably strain will be very effective tuning parameters for this entire class of materials.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Deuterium retention in Be-D co-deposits formed over an ITER relevant parameter space

Be-D co-deposit samples are produced over an extended range of plasma-material interaction parameters reflective of the conditions expected in ITER deposition dominant locations. Deposition temperature, D impact energy, atomic Be deposition rate, and D2 neutral pressure were varied in the ranges 373–623 K, ~2–100 eV, 1–10 × 10 19 m 2 s –1 , and 0.27–13.3 Pa respectively. Thermal desorption spectrometry was carried out on samples, subsequently, to measure the D release profile and retention. In this work, it was found that the D retention in samples agrees well with the existing GDT D/Be scaling over the extended parameter space, and that increased D impact energy and D2 pressure can lead to the observation of a sharp low-temperature release peak at ~440 K in desorption data. Desorption data without the presence of the sharp release mechanism are modeled with TMAP-7 utilizing three traps of de-trapping energies, 0.8, 0.9 and 1.0 eV.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Time-resolved particle image velocimetry

Time-resolved particle image velocimetry (TR-PIV) has become widespread in fluid dynamics. Essentially a velocity field movie, the dynamic content provides temporal as well as spatial information, in contrast to conventional PIV offering only statistical ensembles of flow quantities. From these time series arise further analyses such as accelerometry, space-time correlations, frequency spectra of turbulence including spatial variability, and derivation of pressure fields and forces. The historical development of TR-PIV is chronicled, culminating in an assessment of the current state of technology in high-repetition-rate lasers and high-speed cameras. Commercialization of pulse-burst lasers has expanded TR-PIV into more flows, including the compressible regime, and has achieved MHz rates. Particle response times and peak locking during image interrogation require attention but generally are not impediments to success. Accuracy considerations are discussed, including the risks of noise and aliasing in spectral content. Oversampled TR-PIV measurements allow use of multi-frame image interrogation methods, which improve the precision of the correlation and raise the velocity dynamic range of PIV. In combination with volumetric methods and data assimilation, a full four-dimensional description of a flow is not only achievable but becoming standardized. Lastly, a survey of exemplary applications is followed by a few predictions concerning the future of TR-PIV.

47 OTHER INSTRUMENTATION↗