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66 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on KSbO3 by Materials Project

KSbO3 crystallizes in the cubic Pn-3 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a distorted hexagonal planar geometry to six equivalent O2- atoms. All K–O bond lengths are 2.66 Å. In the second K1+ site, K1+ is bonded in a distorted hexagonal planar geometry to six O2- atoms. There are three shorter (2.71 Å) and three longer (2.93 Å) K–O bond lengths. Sb5+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing SbO6 octahedra. The corner-sharing octahedral tilt angles are 50°. There are a spread of Sb–O bond distances ranging from 2.00–2.05 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+ and two equivalent Sb5+ atoms. In the second O2- site, O2- is bonded to two K1+ and two equivalent Sb5+ atoms to form a mixture of distorted edge and corner-sharing OK2Sb2 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KBiO3 by Materials Project

KBiO3 crystallizes in the cubic Pn-3 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a distorted hexagonal planar geometry to six equivalent O2- atoms. All K–O bond lengths are 2.75 Å. In the second K1+ site, K1+ is bonded in a distorted hexagonal planar geometry to six O2- atoms. There are three shorter (2.75 Å) and three longer (3.06 Å) K–O bond lengths. Bi5+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing BiO6 octahedra. The corner-sharing octahedral tilt angles are 54°. There are a spread of Bi–O bond distances ranging from 2.13–2.18 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+ and two equivalent Bi5+ atoms. In the second O2- site, O2- is bonded to two K1+ and two equivalent Bi5+ atoms to form a mixture of distorted corner and edge-sharing OK2Bi2 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YTl5Cu2(NO2)12 by Materials Project

(Cu)2YTl5(NO2)12 crystallizes in the cubic Pn-3 space group. The structure is three-dimensional and consists of four copper molecules and one YTl5(NO2)12 framework. In the YTl5(NO2)12 framework, Y3+ is bonded to twelve equivalent O2- atoms to form YO12 cuboctahedra that share edges with six equivalent TlO12 cuboctahedra and faces with four equivalent TlO12 cuboctahedra. All Y–O bond lengths are 2.74 Å. There are two inequivalent Tl1+ sites. In the first Tl1+ site, Tl1+ is bonded to twelve O2- atoms to form distorted TlO12 cuboctahedra that share edges with two equivalent YO12 cuboctahedra, edges with four equivalent TlO12 cuboctahedra, and faces with four equivalent TlO12 cuboctahedra. There are a spread of Tl–O bond distances ranging from 3.20–3.57 Å. In the second Tl1+ site, Tl1+ is bonded to twelve O2- atoms to form TlO12 cuboctahedra that share faces with two equivalent YO12 cuboctahedra and faces with six equivalent TlO12 cuboctahedra. There are six shorter (2.85 Å) and six longer (2.95 Å) Tl–O bond lengths. N3+ 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) N–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three Tl1+ and one N3+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one Y3+, two Tl1+, and one N3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K5CeCu2(NO2)12 by Materials Project

K5Ce(NO2)12(Cu)2 crystallizes in the cubic Pn-3 space group. The structure is three-dimensional and consists of four copper molecules and one K5Ce(NO2)12 framework. In the K5Ce(NO2)12 framework, there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to twelve O2- atoms to form KO12 cuboctahedra that share faces with two equivalent CeO12 cuboctahedra and faces with six equivalent KO12 cuboctahedra. There are six shorter (2.78 Å) and six longer (2.85 Å) K–O bond lengths. In the second K1+ site, K1+ is bonded to twelve O2- atoms to form KO12 cuboctahedra that share edges with two equivalent CeO12 cuboctahedra, edges with four equivalent KO12 cuboctahedra, and faces with four equivalent KO12 cuboctahedra. There are a spread of K–O bond distances ranging from 3.11–3.31 Å. Ce3+ is bonded to twelve equivalent O2- atoms to form CeO12 cuboctahedra that share edges with six equivalent KO12 cuboctahedra and faces with four equivalent KO12 cuboctahedra. All Ce–O bond lengths are 2.86 Å. N3+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.25 Å) and one longer (1.27 Å) N–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three K1+ and one N3+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two K1+, one Ce3+, and one N3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K5YNi2(NO2)12 by Materials Project

K5Y(NO2)12(Ni)2 crystallizes in the cubic Pn-3 space group. The structure is three-dimensional and consists of four nickel molecules and one K5Y(NO2)12 framework. In the K5Y(NO2)12 framework, there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to twelve O2- atoms to form KO12 cuboctahedra that share faces with two equivalent YO12 cuboctahedra and faces with six equivalent KO12 cuboctahedra. There are six shorter (2.76 Å) and six longer (2.85 Å) K–O bond lengths. In the second K1+ site, K1+ is bonded to twelve O2- atoms to form KO12 cuboctahedra that share edges with two equivalent YO12 cuboctahedra, edges with four equivalent KO12 cuboctahedra, and faces with four equivalent KO12 cuboctahedra. There are a spread of K–O bond distances ranging from 3.08–3.35 Å. Y3+ is bonded to twelve equivalent O2- atoms to form YO12 cuboctahedra that share edges with six equivalent KO12 cuboctahedra and faces with four equivalent KO12 cuboctahedra. All Y–O bond lengths are 2.77 Å. N3+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.25 Å) and one longer (1.28 Å) N–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three K1+ and one N3+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two K1+, one Y3+, and one N3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K5CeFe2(NO2)12 by Materials Project

K5Ce(NO2)12(Fe)2 crystallizes in the cubic Pn-3 space group. The structure is three-dimensional and consists of four iron molecules and one K5Ce(NO2)12 framework. In the K5Ce(NO2)12 framework, there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to twelve O2- atoms to form KO12 cuboctahedra that share faces with two equivalent CeO12 cuboctahedra and faces with six equivalent KO12 cuboctahedra. There are six shorter (2.81 Å) and six longer (2.86 Å) K–O bond lengths. In the second K1+ site, K1+ is bonded to twelve O2- atoms to form KO12 cuboctahedra that share edges with two equivalent CeO12 cuboctahedra, edges with four equivalent KO12 cuboctahedra, and faces with four equivalent KO12 cuboctahedra. There are a spread of K–O bond distances ranging from 3.02–3.24 Å. Ce3+ is bonded to twelve equivalent O2- atoms to form CeO12 cuboctahedra that share edges with six equivalent KO12 cuboctahedra and faces with four equivalent KO12 cuboctahedra. All Ce–O bond lengths are 2.83 Å. N+2.83+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.25 Å) and one longer (1.28 Å) N–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three K1+ and one N+2.83+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two K1+, one Ce3+, and one N+2.83+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K5CeNi2(NO2)12 by Materials Project

K5Ce(NO2)12(Ni)2 crystallizes in the cubic Pn-3 space group. The structure is three-dimensional and consists of four nickel molecules and one K5Ce(NO2)12 framework. In the K5Ce(NO2)12 framework, there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to twelve O2- atoms to form KO12 cuboctahedra that share faces with two equivalent CeO12 cuboctahedra and faces with six equivalent KO12 cuboctahedra. There are six shorter (2.79 Å) and six longer (2.86 Å) K–O bond lengths. In the second K1+ site, K1+ is bonded to twelve O2- atoms to form KO12 cuboctahedra that share edges with two equivalent CeO12 cuboctahedra, edges with four equivalent KO12 cuboctahedra, and faces with four equivalent KO12 cuboctahedra. There are a spread of K–O bond distances ranging from 3.10–3.35 Å. Ce3+ is bonded to twelve equivalent O2- atoms to form CeO12 cuboctahedra that share edges with six equivalent KO12 cuboctahedra and faces with four equivalent KO12 cuboctahedra. All Ce–O bond lengths are 2.85 Å. N3+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.25 Å) and one longer (1.27 Å) N–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three K1+ and one N3+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two K1+, one Ce3+, and one N3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cs5CeNi2(NO2)12 by Materials Project

Cs5Ce(NO2)12(Ni)2 crystallizes in the cubic Pn-3 space group. The structure is three-dimensional and consists of four nickel molecules and one Cs5Ce(NO2)12 framework. In the Cs5Ce(NO2)12 framework, there are two inequivalent Cs1+ sites. In the first Cs1+ site, Cs1+ is bonded to twelve O2- atoms to form CsO12 cuboctahedra that share faces with two equivalent CeO12 cuboctahedra and faces with six equivalent CsO12 cuboctahedra. There are six shorter (3.10 Å) and six longer (3.15 Å) Cs–O bond lengths. In the second Cs1+ site, Cs1+ is bonded to twelve O2- atoms to form CsO12 cuboctahedra that share edges with two equivalent CeO12 cuboctahedra, edges with four equivalent CsO12 cuboctahedra, and faces with four equivalent CsO12 cuboctahedra. There are a spread of Cs–O bond distances ranging from 3.34–3.62 Å. Ce3+ is bonded to twelve equivalent O2- atoms to form CeO12 cuboctahedra that share edges with six equivalent CsO12 cuboctahedra and faces with four equivalent CsO12 cuboctahedra. All Ce–O bond lengths are 2.97 Å. N3+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.25 Å) and one longer (1.28 Å) N–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to three Cs1+ and one N3+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to two Cs1+, one Ce3+, and one N3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb5CeCu2(NO2)12 by Materials Project

Rb5Ce(NO2)12(Cu)2 crystallizes in the cubic Pn-3 space group. The structure is three-dimensional and consists of four copper molecules and one Rb5Ce(NO2)12 framework. In the Rb5Ce(NO2)12 framework, there are two inequivalent Rb1+ sites. In the first Rb1+ site, Rb1+ is bonded to twelve O2- atoms to form RbO12 cuboctahedra that share faces with two equivalent CeO12 cuboctahedra and faces with six equivalent RbO12 cuboctahedra. There are six shorter (2.90 Å) and six longer (2.99 Å) Rb–O bond lengths. In the second Rb1+ site, Rb1+ is bonded to twelve O2- atoms to form distorted RbO12 cuboctahedra that share edges with two equivalent CeO12 cuboctahedra, edges with four equivalent RbO12 cuboctahedra, and faces with four equivalent RbO12 cuboctahedra. There are a spread of Rb–O bond distances ranging from 3.23–3.56 Å. Ce3+ is bonded to twelve equivalent O2- atoms to form CeO12 cuboctahedra that share edges with six equivalent RbO12 cuboctahedra and faces with four equivalent RbO12 cuboctahedra. All Ce–O bond lengths are 2.82 Å. N3+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.25 Å) and one longer (1.27 Å) N–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three Rb1+ and one N3+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two Rb1+, one Ce3+, and one N3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2022

How effective is the Brink–Axel hypothesis for astrophysical weak rates?

We explore the effectiveness of the Brink–Axel hypothesis (BAH) for the computation of stellar electron capture (EC) and β-decay (BD) rates, namely that the transition strength function depends only upon the transition energy and not upon the details of the initial state. For this purpose, we calculated Gamow–Teller (GT) strength distributions for a selection of sd-shell nuclides, using two different microscopic models, namely the proton–neutron quasiparticle random phase approximation and the full configuration-interaction shell model, taking into account the first 100 states of both the initial and final nuclides. The GT transition strengths among these levels evolve with initial state energy. These transition strength functions we folded into weak-interaction mediated rates in stellar matter, specifically EC and BD rates, for a range of densities 10 g cm –3 ≤ ρ ≤ 10 11 g cm –3 and range of temperatures 1 GK ≤ T ≤ 30 GK. When transitions from excited states were approximated using the BAH, augmented by so-called 'back-resonance' transitions, the rates were affected by up to three orders of magnitude or more at high temperatures and densities. Furthermore the BAH is not a reliable approximation for the calculation of stellar rates, especially in high temperature–density environments.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Materials Data on CeTl5Cu2(NO2)12 by Materials Project

(Cu)2CeTl5(NO2)12 crystallizes in the cubic Pn-3 space group. The structure is three-dimensional and consists of four copper molecules and one CeTl5(NO2)12 framework. In the CeTl5(NO2)12 framework, Ce3+ is bonded to twelve equivalent O2- atoms to form CeO12 cuboctahedra that share edges with six equivalent TlO12 cuboctahedra and faces with four equivalent TlO12 cuboctahedra. All Ce–O bond lengths are 2.83 Å. There are two inequivalent Tl1+ sites. In the first Tl1+ site, Tl1+ is bonded to twelve O2- atoms to form TlO12 cuboctahedra that share faces with two equivalent CeO12 cuboctahedra and faces with six equivalent TlO12 cuboctahedra. There are six shorter (2.81 Å) and six longer (2.89 Å) Tl–O bond lengths. In the second Tl1+ site, Tl1+ is bonded to twelve O2- atoms to form TlO12 cuboctahedra that share edges with two equivalent CeO12 cuboctahedra, edges with four equivalent TlO12 cuboctahedra, and faces with four equivalent TlO12 cuboctahedra. There are a spread of Tl–O bond distances ranging from 3.15–3.41 Å. N3+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.25 Å) and one longer (1.27 Å) N–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three Tl1+ and one N3+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one Ce3+, two Tl1+, and one N3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Probing the Isospin Composition of Short-Range Correlated Pairs at Jefferson Lab Hall B

Nucleons in short-range correlated (SRC) pairs, due to their close proximity and high relative momentum, can provide insight into the short-range part of the strong nuclear interaction. In particular, the prevalence of np pairs is due to the dominance of a tensor term for correlated nucleons with momenta of approximately 400?600 MeV/c. This dissertation comprises two studies advancing the community?s understanding of the isospin composition of SRC pairs. First, I performed a study of proton and neutron knockout from initially low-momentum and high-momentum states in 3He. Previous work has shown that protons are disproportionately represented in high-momentum states in neutron-rich nuclei. I demonstrate that spectral functions for the proton-rich nucleus 3He predict, in agreement with data, that neutrons are disproportionately represented in high-momentum states, but that 3He does not display the same strong prevalence of np pairs that is observed in larger nuclei. Second, Generalized Contact Formalism (GCF), a well-supported theory for predicting SRC behavior, predicts the transition from an isospin-dependent, tensor-dominant interaction at intermediate distances to a scalar-dominant, isospin-independent interaction at very short distances. This dissertation uses data from the CLAS12 Nuclear Targets Experiments in Hall B at Jefferson Lab to measure the relative abundances of pp and pn pairs for increasing relative momentum and decreasing separation. I provide an independent confirmation of the previously-observed increase in pp pairs at increasing momentum of the struck nucleon. I also contribute to the application of the new CLAS12 Central Neutron Detector by precisely measuring the neutron detection efficiency and developing a machine learning model for rejecting charged particle background.

Seroka, Erin↗