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At least 307 records · Page 17

Direct-Y: Fast Acquisition of the GPS PPS Signal

The NAVSTAR Global Positioning System (GPS) provides positioning and time information to military users via the Precise Positioning Service (PPS) which typically allows users a significant margin of precision over the commercially available Standard Positioning Service (SPS), Military sets that rely on first acquiring the SPS Coarse Acquisition (C/A) code, read from the data message the handover word (HOW) that provides the time-of-signal transmission needed to acquire and lock onto the PPS Y-code. Under extreme battlefield conditions, the use of GPS would be denied to the warfighter who cannot pick up the un-encrypted C/A code. Studies are underway at the GPS Joint Program Office (JPO) at the Space and Missile Center, Los Angeles Air Force Base that are aimed at developing the capability to directly acquire Y-code without first acquiring C/A code. This paper briefly outlines efforts to develop 'direct-Y' acquisition, and various approaches to solving this problem. The potential ramifications of direct-Y to military users are also discussed.

Namoos, Omar M.↗

New Observations of the NO(y)/N2O Correlation in the lower Stratosphere

During the Airborne Arctic Stratospheric Expedition II (AASE II), September 1991 through March 1992, in situ measurements of reactive nitrogen (NO(y)) and N2O were made in the Northern Hemisphere lower stratosphere. We present an analysis of this new data and compare it with results from similar data taken during AASE in the winter of 1989. In the Northern Hemisphere there is a consistent linear correlation of N2O and NO(y) which shows no interannual variation. Cases of departure from a linear correlation are examined and classified as being due to denitrification (NO(y) loss) or sampling air from a region where the photochemical lifetime of NO(y) is decreased. The latter case was observed for the first time in the winter of 1992.

Lowenstein, M.↗

Airborne Measurements of NO, NO2, and NO(y) as Related to NASA's Pacific Exploratory Mission

The Tropospheric Trace Gas and Airborne Measurements Group's (TTGAMG) efforts on NASA GTE (Global Tropospheric Experiment) PEM (Pacific Exploratory Mission) West A & B field campaign primarily involved the acquisition of NO, NO2 and NO(y) measurements, as well as the subsequent analysis and interpretation of the data base obtained during the PEM West field campaign. These investigations focused on the distribution of trace gases, sources and sinks of ozone, ozone producing precursors with a heavy emphasize on ozone's photochemical state, and the partitioning of the molecules within the NO(y) family over the north western Pacific Ocean. The two components of PEM West were focused on observing air masses as they reached the Asian Continent (PEM West A) or as the air mass departed the Asian Continent (PEM West B). NO(x) concentrations play a pivotal role in controlling the photochemical lifetime of ozone in these environments, and understanding the NO(x) species partitioning is paramount. The transport of NO(x) into the regions, in the form of longer lived NO(y) family members, was examined in relation to the comparison of natural occurring sources of NO(x) (i.e., lightning and stratosphere/troposphere exchange) to those produced as a result of anthropogenic activity (i.e., biomass burning and aircraft emissions). The TTGAMG's measurements of NOx and NO(y), in conjunction with other investigators' measurements of PAN (H. B. Singh's group) and HNO3 (R. W. Talbot's group), have been used to assess the total reactive odd nitrogen levels over the study regions, the partitioning of the reactive odd nitrogen species in their various forms, and the usefulness of the NO, measurement and its measurement technique. The TTGAMG's primary PEM West objectives were the characterization of the factors controlling the distribution and fate of reactive odd nitrogen compounds over the western Pacific Ocean and an analysis of the concentration of various trace gases in the troposphere as the air mass aged by both dynamical mixing and photochemical processes in the troposphere.

Sandholm, Scott↗

Evolution of the Global Aurora During Positive IMF B(sub z) and Varying IMF B(sub y) Conditions

The DE 1 imaging instrumentation provides a full view of the entire auroral oval every 12 min for several hours during each orbit. We examined five examples of global evolution of the aurora that occurred during the northern hemisphere winter of 1981-1982 when the z component of the interplanetary magnetic field (IMF) was positive and the y component was changing sign. Evolution of an expanded auroral emission region into a theta aurora appears to require a change in the sign of B(sub y) during northward Interplanetary Magnetic Field. Theta aurora are formed both from expanded duskside emission regions (B(sub y) changes from positive to negative) and dawnside emission regions (B(sub y) changes from negative to positive), however the dawnside-originating and duskside-originating evolutions are not mirror images. The persistence of a theta aurora after its formation suggests that there may be no clear relationship between the theta aurora pattern and the instantaneous configuration of the IMF.

Cumnock, J. A.↗

Performance Analysis of the NAS Y-MP Workload

This paper describes the performance characteristics of the computational workloads on the NAS Cray Y-MP machines, a Y-MP 832 and later a Y-MP 8128. Hardware measurements indicated that the Y-MP workload performance matured over time, ultimately sustaining an average throughput of 0.8 GFLOPS and a vector operation fraction of 87%. The measurements also revealed an operation rate exceeding 1 per clock period, a well-balanced architecture featuring a strong utilization of vector functional units, and an efficient memory organization. Introduction of the larger memory 8128 increased throughput by allowing a more efficient utilization of CPUs. Throughput also depended on the metering of the batch queues; low-idle Saturday workloads required a buffer of small jobs to prevent memory starvation of the CPU. UNICOS required about 7% of total CPU time to service the 832 workloads; this overhead decreased to 5% for the 8128 workloads. While most of the system time went to service I/O requests, efficient scheduling prevented excessive idle due to I/O wait. System measurements disclosed no obvious bottlenecks in the response of the machine and UNICOS to the workloads. In most cases, Cray-provided software tools were- quite sufficient for measuring the performance of both the machine and operating, system.

Bergeron, Robert J.↗

Test and Analysis Correlation for a Y-Joint Specimen for a Composite Cryotank

The Composite Cryotank Technology Demonstration (CCTD) project under NASA's Game Changing Development Program (GCDP) developed space technologies using advanced composite materials. Under CCTD, NASA funded the Boeing Company to design and test a number of element-level joint specimens as a precursor to a 2.4-m diameter composite cryotank. Preliminary analyses indicated that the y-joint in the cryotank had low margins of safety; hence the y-joint was considered to be a critical design region. The y-joint design includes a softening strip wedge to reduce localized shear stresses at the skirt/dome interface. In this paper, NASA-developed analytical models will be correlated with the experimental results of a series of positive-peel y-joint specimens from Boeing tests. Initial analytical models over-predicted the experimental strain gage readings in the far-field region by approximately 10%. The over-prediction was attributed to uncertainty in the elastic properties of the laminate and a mismatch between the thermal expansion of the strain gages and the laminate. The elastic properties of the analytical model were adjusted to account for the strain gage differences. The experimental strain gages also indicated a large non-linear effect in the softening strip region that was not predicted by the analytical model. This non-linear effect was attributed to delamination initiating in the softening strip region at below 20% of the failure load for the specimen. Because the specimen was contained in a thermally insulated box during cryogenic testing to failure, delamination initiation and progression was not visualized during the test. Several possible failure initiation locations were investigated, and a most likely failure scenario was determined that correlated well with the experimental data. The most likely failure scenario corresponded to damage initiating in the softening strip and delamination extending to the grips at final failure.

Mason, Brian H.↗

A 40-y record reveals gradual Antarctic sea ice increases followed by decreases at rates far exceeding the rates seen in the Arctic

Following over 3 decades of gradual but uneven increases in sea ice coverage, the yearly average Antarctic sea ice extents reached a record high of 12.8 × 106(6) sq. km in 2014, followed by a decline so precipitous that they reached their lowest value in the 40-y 1979– 2018 satellite multichannel passive-microwave record, 10.7 × 10^(6) sq. km, in 2017. In contrast, it took the Arctic sea ice cover a full 3 decades to register a loss that great in yearly average ice extents. Still, when considering the 40-y record as a whole, the Antarctic sea ice continues to have a positive overall trend in yearly average ice extents, although at 11,300 ± 5,300 sq. km/y, this trend is only 50% of the trend for 1979–2014, before the precipitous decline. Four of the 5 sectors into which the Antarctic sea ice cover is divided all also have 40-y positive trends that are well reduced from their 2014–2017 values. The one anomalous sector in this regard, the Bellingshausen/Amundsen Seas, has a 40-y negative trend, with the yearly average ice extents decreasing overall in the first 3 decades, reaching a minimum in 2007, and exhibiting an overall upward trend since 2007 (i.e., reflecting a reversal in the opposite direction from the other 4 sectors and the Antarctic sea ice cover as a whole).

sea ice↗

Theoretical Prediction of Thermal Expansion Anisotropy for Y 2 Si 2 O 7 Environmental Barrier Coatings Using a Deep Neural Network Potential and Comparison to Experiment

Environmental barrier coatings (EBCs) are an enabling technology for silicon carbide (SiC)-based ceramic matrix composites (CMCs) in extreme environments such as gas turbine engines. However, development of new coating systems is hindered by the large design space and difficulty in predicting properties for these materials. Density Functional Theory (DFT) has successfully been used to model and predict some thermodynamic and thermo-mechanical properties of high-temperature ceramics for EBCs, although these calculations are challenging due to their high computational costs. In this work, we use machine learning to train a deep neural network potential (DNP) for Y 2 Si 2 O 7 , which is then applied to calculate thermodynamic and thermo-mechanical properties at near-DFT accuracy much faster and using less computational resources than DFT. We use this DNP to predict phonon-based thermodynamic properties of Y 2 Si 2 O 7 with good agreement to DFT and experiments. We also utilize the DNP to calculate the anisotropic, lattice direction-dependent coefficients of thermal expansion (CTEs) for Y 2 Si 2 O 7 . Molecular dynamics trajectories using the DNP correctly demonstrate accurate prediction of the anisotropy of the CTE in good agreement with diffraction experiments. In the future, this DNP could be applied to accelerate additional property calculations for Y 2 Si 2 O 7 compared to DFT or experiments.

rare earth silicates↗

CAAS-3S Radiation Testing for Y-12 and UPF with Godiva-IV

The Y-12 National Security Complex and the Uranium Processing Facility (UPF) selected the Mirion CAAS-3S as the Criticality Accident Alarm System for UPF and for Y-12 facilities replacing their legacy CAAS as part of efforts to extend the facility lifespans. As part of this process, the CAAS-3S system was exposed to a high radiation dose and dose rate during reactor testing with the Godiva-IV fast burst reactor. The reactor testing was designed around preliminary analyses that determined Y-12 and UPF requirements, and simulations of the radiation field within the reactor facility were used to determine reactor operating parameters, CAAS equipment locations, and the design of a neutron shield wall. This paper presents the design and results of the testing, and discusses how the test results were interpreted by criticality safety engineers at Y-12 and UPF.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Materials Data on Y(AlSi)2 by Materials Project

YAl2Si2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Y is bonded to six equivalent Si atoms to form distorted YSi6 octahedra that share corners with twelve equivalent AlSi4 tetrahedra, edges with six equivalent YSi6 octahedra, and edges with six equivalent AlSi4 tetrahedra. All Y–Si bond lengths are 2.97 Å. Al is bonded to four equivalent Si atoms to form distorted AlSi4 tetrahedra that share corners with six equivalent YSi6 octahedra, corners with six equivalent AlSi4 tetrahedra, edges with three equivalent YSi6 octahedra, and edges with three equivalent AlSi4 tetrahedra. The corner-sharing octahedra tilt angles range from 21–55°. There are three shorter (2.51 Å) and one longer (2.53 Å) Al–Si bond lengths. Si is bonded to three equivalent Y and four equivalent Al atoms to form a mixture of distorted edge and corner-sharing SiY3Al4 pentagonal bipyramids.

36 MATERIALS SCIENCE↗

Materials Data on Y(AlGe)2 by Materials Project

Al2Ge2Y crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Y is bonded to six equivalent Ge atoms to form distorted YGe6 octahedra that share corners with twelve equivalent AlGe4 tetrahedra, edges with six equivalent YGe6 octahedra, and edges with six equivalent AlGe4 tetrahedra. All Y–Ge bond lengths are 3.01 Å. Al is bonded to four equivalent Ge atoms to form distorted AlGe4 tetrahedra that share corners with six equivalent YGe6 octahedra, corners with six equivalent AlGe4 tetrahedra, edges with three equivalent YGe6 octahedra, and edges with three equivalent AlGe4 tetrahedra. The corner-sharing octahedra tilt angles range from 20–55°. There are three shorter (2.56 Å) and one longer (2.57 Å) Al–Ge bond lengths. Ge is bonded to three equivalent Y and four equivalent Al atoms to form a mixture of distorted edge and corner-sharing GeY3Al4 pentagonal bipyramids.

36 MATERIALS SCIENCE↗

Materials Data on Y(MnGe)2 by Materials Project

YMn2Ge2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Y is bonded in a 8-coordinate geometry to eight equivalent Ge atoms. All Y–Ge bond lengths are 3.08 Å. Mn is bonded to four equivalent Ge atoms to form a mixture of corner and edge-sharing MnGe4 tetrahedra. All Mn–Ge bond lengths are 2.44 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Y, four equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.61 Å.

36 MATERIALS SCIENCE↗

Materials Data on Y(PO3)3 by Materials Project

Y(PO3)3 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are two inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded to six O2- atoms to form YO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Y–O bond distances ranging from 2.25–2.31 Å. In the second Y3+ site, Y3+ is bonded to six O2- atoms to form YO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Y–O bond distances ranging from 2.26–2.29 Å. There are four inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent YO6 octahedra and corners with two equivalent PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 11–39°. There is two shorter (1.50 Å) and two longer (1.62 Å) P–O bond length. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent YO6 octahedra and corners with two equivalent PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 11–38°. There is two shorter (1.50 Å) and two longer (1.61 Å) P–O bond length. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two YO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 25–29°. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two YO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 24–38°. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. There are eleven inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one Y3+ and one P5+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Y3+ and one P5+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Y3+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two P5+ atoms. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Y3+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two P5+ atoms. In the eighth O2- site, O2- is bonded in a linear geometry to one Y3+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a distorted linear geometry to one Y3+ and one P5+ atom. In the tenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Y3+ and one P5+ atom. In the eleventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Y3+ and one P5+ atom.

36 MATERIALS SCIENCE↗

Materials Data on Y(IO3)3 by Materials Project

Y(O3I)3 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of one Y(O3I)3 sheet oriented in the (-1, 0, 2) direction. Y3+ is bonded in a 7-coordinate geometry to eight O2- atoms. There are a spread of Y–O bond distances ranging from 2.31–2.86 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Y3+ and one I5+ atom. The O–I bond length is 1.85 Å. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one I5+ atom. The O–I bond length is 1.84 Å. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one Y3+ and one I5+ atom. The O–I bond length is 1.85 Å. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one Y3+ and one I5+ atom. The O–I bond length is 1.82 Å. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to one I5+ atom. The O–I bond length is 1.86 Å. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to one Y3+ and one I5+ atom. The O–I bond length is 1.84 Å. In the seventh O2- site, O2- is bonded in a bent 120 degrees geometry to one Y3+ and one I5+ atom. The O–I bond length is 1.84 Å. In the eighth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Y3+ and one I5+ atom. The O–I bond length is 1.85 Å. In the ninth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Y3+ and one I5+ atom. The O–I bond length is 1.84 Å. There are three inequivalent I5+ sites. In the first I5+ site, I5+ is bonded in a 3-coordinate geometry to three O2- atoms. In the second I5+ site, I5+ is bonded in a 6-coordinate geometry to three O2- atoms. In the third I5+ site, I5+ is bonded in a 5-coordinate geometry to three O2- atoms.

36 MATERIALS SCIENCE↗

Materials Data on Y(HO)3 by Materials Project

Y(OH)3 crystallizes in the monoclinic Pm space group. The structure is three-dimensional. there are two inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Y–O bond distances ranging from 2.40–2.64 Å. In the second Y3+ site, Y3+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Y–O bond distances ranging from 2.40–2.62 Å. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to three Y3+ and one H1+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to three Y3+ and one H1+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to three Y3+ and one H1+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to three Y3+ and one H1+ atom. In the fifth O2- site, O2- is bonded in a single-bond geometry to three Y3+ and one H1+ atom. In the sixth O2- site, O2- is bonded in a single-bond geometry to three Y3+ and one H1+ atom.

36 MATERIALS SCIENCE↗

Materials Data on Y(PO3)3 by Materials Project

Y(PO3)3 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are two inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Y–O bond distances ranging from 2.12–2.87 Å. In the second Y3+ site, Y3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Y–O bond distances ranging from 2.04–2.81 Å. There are six inequivalent P5+ sites. In the first P5+ site, P5+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There are a spread of P–O bond distances ranging from 1.48–1.73 Å. In the second 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 1.48–1.65 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 1.47–1.63 Å. In the fourth 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 1.47–1.61 Å. In the fifth P5+ site, P5+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There is two shorter (1.51 Å) and one longer (1.67 Å) P–O bond length. In the sixth 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 1.49–1.63 Å. There are eighteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to two Y3+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two Y3+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Y3+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one Y3+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Y3+ and one P5+ atom. 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 single-bond geometry to one Y3+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a single-bond geometry to one P5+ atom. In the ninth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the tenth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the eleventh O2- site, O2- is bonded in a single-bond geometry to one Y3+ atom. In the twelfth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Y3+ and two P5+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Y3+ and one P5+ atom. In the fourteenth O2- site, O2- is bonded in a single-bond geometry to one Y3+ atom. In the fifteenth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the sixteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Y3+ and one P5+ atom. In the seventeenth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the eighteenth O2- site, O2- is bonded in a 2-coordinate geometry to one Y3+ and one P5+ atom.

36 MATERIALS SCIENCE↗

Materials Data on Y(BiO2)3 by Materials Project

Y(BiO2)3 is Ilmenite-like structured and crystallizes in the trigonal R-3 space group. The structure is three-dimensional. there are two inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded in an octahedral geometry to six equivalent O2- atoms. All Y–O bond lengths are 2.29 Å. In the second Y3+ site, Y3+ is bonded in an octahedral geometry to six equivalent O2- atoms. All Y–O bond lengths are 2.29 Å. Bi3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Bi–O bond distances ranging from 2.23–2.63 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to one Y3+ and three equivalent Bi3+ atoms to form a mixture of distorted edge and corner-sharing OYBi3 trigonal pyramids. In the second O2- site, O2- is bonded to one Y3+ and three equivalent Bi3+ atoms to form a mixture of distorted edge and corner-sharing OYBi3 trigonal pyramids.

36 MATERIALS SCIENCE↗

Materials Data on Y(NO3)3 by Materials Project

Y(NO3)3 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of one Y(NO3)3 sheet oriented in the (0, 0, 1) direction. Y3+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Y–O bond distances ranging from 2.37–2.76 Å. There are three inequivalent N5+ sites. In the first N5+ site, N5+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of N–O bond distances ranging from 1.25–1.28 Å. In the second N5+ site, N5+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.26 Å) and two longer (1.27 Å) N–O bond length. In the third N5+ site, N5+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of N–O bond distances ranging from 1.24–1.31 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one Y3+ and one N5+ atom. In the second O2- site, O2- is bonded in a distorted L-shaped geometry to one Y3+ and one N5+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Y3+ and one N5+ atom. In the fourth O2- site, O2- is bonded in a distorted water-like geometry to one Y3+ and one N5+ atom. In the fifth O2- site, O2- is bonded in a distorted L-shaped geometry to one Y3+ and one N5+ atom. In the sixth O2- site, O2- is bonded in a single-bond geometry to one Y3+ and one N5+ atom. In the seventh O2- site, O2- is bonded in a distorted L-shaped geometry to one Y3+ and one N5+ atom. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to one Y3+ and one N5+ atom. In the ninth O2- site, O2- is bonded in a distorted L-shaped geometry to one Y3+ and one N5+ atom.

36 MATERIALS SCIENCE↗