Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Ac”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 811 records · Page 45
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Example Alternative Compliance Annual Report: EPAct State and Alternative Fuel Provider Fleet Program User Guide

The U.S. Department of Energy developed an electronic reporting spreadsheet to facilitate fleets' preparation of a complete Alternative Compliance (AC) annual report. All fleets that participate in AC are encouraged to use the spreadsheet. The following examples include one AC annual report that uses the spreadsheet and one AC annual report that does not use the spreadsheet. Both examples include all components that must be included in a fleet's AC annual report. For further instructions on how to use the reporting spreadsheet, review the Alternative Compliance Guidance Document.

ADVANCED PROPULSION SYSTEMS,ENERGY PLANNING, POLIC↗
NASA NTRSDate not supplied

Alternating Direct Current (ADC) - A New Form of Efficient Energy Transmission for Renewable Sources

The prevailing means of electricity transmission through Direct Current (DC) and Alternating Current (AC) have limitations with the ongoing transition to renewable energy sources. In this paper, we discuss a new form of energy transmission, known as alternating direct current (ADC) that would provide significant savings in energy consumption and simultaneously allow efficient utilization of generated energy from renewable sources. This has become possible due to substantial advances in electronics and optoelectronics technologies since the days of Nicholas Tesla and Thomas Edison. Recent efforts of implementing the proposed ADC technology in relevant environments have demonstrated significant energy savings and opened a new paradigm that has the potential to provide an efficient and cost-effective pathway for transition to renewable energy sources even with the existing grid infrastructure. The DC power utilization initiated by Thomas Edison can be stored in battery arrangement but suffers from line loss and hence is not efficient for long-distance transmission. However, AC power developed by Nicholas Tesla cannot be stored efficiently but can be transmitted over long distances due to significantly lower line losses. Currently, AC power is the global foundational energy transmission methodology used because of events that took place over 135 years ago involving Edison, Tesla, and Westinghouse, and since AC power can transmit long distances from power plants to end users efficiently and economically. Approximately 50 years ago, the introduction of semiconductors in commercialized electronic devices and products changed the way people consume electricity. Also, over the years, the expanding adaptation of nonlinear loads has adversely affected the grid stability and hence the utility infrastructures worldwide.

AC↗
DOE OSTI2021

Performance Analysis and Limiting Parameters of Cross-flow Membrane-based Liquid-desiccant Air Dehumidifiers

We report that to dehumidify a humid air stream, existing air conditioning (AC) systems substantially overcool the outdoor humid air below its dew point, thereby significantly reducing energy efficiency. Directly capturing humidity, membrane-based liquid-desiccant dehumidification systems separate sensible and latent cooling (SSLC) loads and thus offer a promising pathway for a high-performance AC solution. Design of an energy-efficient SSLC-AC system, however, rests largely on detailed understating of the dehumidification process. While some studies have identified the dehumidification process mainly depends on membrane characteristics, other studies have argued that the process is limited by desiccant liquid or alternatively air thermo-hydraulic physics for typical humid climate conditions. The present study examines performance and physics of the membrane-based liquid-desiccant dehumidification process over a wide range of climate conditions through a novel 3D, two-phase, multi-species CFD model. Decoupling the thermodynamic and hydraulic effects, the study reveals that the dehumidification rate is a linear function of the water vapor pressure potential ($J=α ΔP$) summarizing the system's thermodynamic state. The slope of the curve (i.e., α) depends on hydraulic transport characteristics of the membrane pores, air stream, and desiccant solution. More importantly, it was found that the air dehumidification process is mainly limited by the air-side transport physics for thin liquid-desiccant films and commonly used porous superhydrophobic membranes. Additionally, results show that, depending on ambient/desiccant conditions and physical dehumidifier characteristics, energy effectiveness and dehumidification rate vary from 13 to 34% and from 0.13 to 1.4 g m -2 s -1 , respectively. Therefore, the present study allows to efficiently design future SSLC-based AC systems exhibiting high performance energy metrics.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2023

Advanced silicon tracking detector developments for the future Electron-Ion Collider

The proposed Electron-Ion Collider (EIC) will operate high-luminosity high-energy electron+proton and electron+nucleus collisions at the collision energies from 20 GeV to 141 GeV to solve several fundamental questions in the high energy and nuclear physics fields. Its instantaneous luminosity can reach 10 33-34 cm -2 s -1 and the bunching crossing rate is around 10 ns. The EIC project has received CD1 approval from the US DOE in 2021 and moves toward the machine design and preparation for construction. To realize various particle measurements with high precision at the future EIC, a low material-budget and high-granularity silicon vertex and tracking detector with fine spatial and momentum resolutions and nearly 4π solid angle coverage is desired. The Monolithic Active Pixel Sensor (MAPS) and AC Coupled Low Gain Avalanche Diode (AC-LGAD) technologies stand out of several advanced technology options for the EIC silicon vertex and tracking detector subsystems. The MAPS technology has advanced features of low material budget, low power consumption, good radiation resistance and fine spatial resolution. The AC-LGAD technology can achieve fast timing resolution. Latest studies and progress of the EIC silicon vertex and tracking detector conceptual design, performance validations in simulation and ongoing MAPS and AC-LGAD R&D will be shown. Furthermore, schedule and plan of the EIC project detector development will be discussed as well.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2020

Skyrmion pinball and directed motion on obstacle arrays

Abstract We examine skyrmions interacting with a square array of obstacles under ac drives applied in one or two directions. For a single direction of ac driving, we find that the Magnus force in conjunction with the obstacle interactions can create elliptical skyrmion orbits of increasing size, leading to localized phases, chaotic phases, and translating or ratcheting orbits. Under two ac drives that are out of phase by 90° and applied in two directions, the skyrmions form localized commensurate orbits that encircle an integer number of obstacles, similar to the electron pinball effect observed for electrons in antidot lattices. As a function of ac amplitude, Magnus force strength, and obstacle size, we find that chaotic scattering regimes and directed motion can emerge even in the absence of asymmetry in the substrate. The directed motion follows different symmetry axes of the periodic substrate, and we observe a variety of reversed ratchet effects. The Magnus force in the skyrmion system produces a significantly larger number of directed motion regimes than are exhibited by overdamped systems. We discuss how these results could be used to move skyrmions in a controlled way for possible applications.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2020

Materials Data on AcAg3 by Materials Project

AcAg3 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Ac is bonded to twelve Ag atoms to form a mixture of distorted corner and face-sharing AcAg12 cuboctahedra. There are a spread of Ac–Ag bond distances ranging from 3.36–3.51 Å. There are two inequivalent Ag sites. In the first Ag site, Ag is bonded in a 10-coordinate geometry to four equivalent Ac and six Ag atoms. There are a spread of Ag–Ag bond distances ranging from 2.94–2.97 Å. In the second Ag site, Ag is bonded in a 10-coordinate geometry to four equivalent Ac and six equivalent Ag atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AcLa3 by Materials Project

AcLa3 is Copper-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ac is bonded to twelve La atoms to form AcLa12 cuboctahedra that share corners with four equivalent AcLa12 cuboctahedra, corners with eight equivalent LaAc4La8 cuboctahedra, edges with eight equivalent AcLa12 cuboctahedra, edges with sixteen equivalent LaAc4La8 cuboctahedra, faces with four equivalent AcLa12 cuboctahedra, and faces with fourteen LaAc4La8 cuboctahedra. There are four shorter (3.80 Å) and eight longer (3.81 Å) Ac–La bond lengths. There are two inequivalent La sites. In the first La site, La is bonded to four equivalent Ac and eight La atoms to form LaAc4La8 cuboctahedra that share corners with twelve equivalent LaAc4La8 cuboctahedra, edges with eight equivalent AcLa12 cuboctahedra, edges with sixteen LaAc4La8 cuboctahedra, faces with four equivalent AcLa12 cuboctahedra, and faces with fourteen LaAc4La8 cuboctahedra. There are four shorter (3.80 Å) and four longer (3.81 Å) La–La bond lengths. In the second La site, La is bonded to four equivalent Ac and eight equivalent La atoms to form LaAc4La8 cuboctahedra that share corners with four equivalent LaAc4La8 cuboctahedra, corners with eight equivalent AcLa12 cuboctahedra, edges with twenty-four LaAc4La8 cuboctahedra, faces with six equivalent AcLa12 cuboctahedra, and faces with twelve LaAc4La8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AcDy3 by Materials Project

AcDy3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ac is bonded to twelve Dy atoms to form AcDy12 cuboctahedra that share corners with four equivalent AcDy12 cuboctahedra, corners with eight equivalent DyAc4Dy8 cuboctahedra, edges with eight equivalent AcDy12 cuboctahedra, edges with sixteen equivalent DyAc4Dy8 cuboctahedra, faces with four equivalent AcDy12 cuboctahedra, and faces with fourteen DyAc4Dy8 cuboctahedra. There are eight shorter (3.65 Å) and four longer (3.68 Å) Ac–Dy bond lengths. There are two inequivalent Dy sites. In the first Dy site, Dy is bonded to four equivalent Ac and eight Dy atoms to form DyAc4Dy8 cuboctahedra that share corners with twelve equivalent DyAc4Dy8 cuboctahedra, edges with eight equivalent AcDy12 cuboctahedra, edges with sixteen DyAc4Dy8 cuboctahedra, faces with four equivalent AcDy12 cuboctahedra, and faces with fourteen DyAc4Dy8 cuboctahedra. There are four shorter (3.65 Å) and four longer (3.68 Å) Dy–Dy bond lengths. In the second Dy site, Dy is bonded to four equivalent Ac and eight equivalent Dy atoms to form DyAc4Dy8 cuboctahedra that share corners with four equivalent DyAc4Dy8 cuboctahedra, corners with eight equivalent AcDy12 cuboctahedra, edges with twenty-four DyAc4Dy8 cuboctahedra, faces with six equivalent AcDy12 cuboctahedra, and faces with twelve DyAc4Dy8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ac3In by Materials Project

In(Ac)3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Ac is bonded in a 4-coordinate geometry to four equivalent In atoms. There are two shorter (3.68 Å) and two longer (3.86 Å) Ac–In bond lengths. In is bonded to twelve equivalent Ac atoms to form a mixture of corner and face-sharing InAc12 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AcSm3 by Materials Project

AcSm3 is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ac is bonded to twelve Sm atoms to form AcSm12 cuboctahedra that share corners with four equivalent AcSm12 cuboctahedra, corners with eight equivalent SmAc4Sm8 cuboctahedra, edges with eight equivalent AcSm12 cuboctahedra, edges with sixteen equivalent SmAc4Sm8 cuboctahedra, faces with four equivalent AcSm12 cuboctahedra, and faces with fourteen SmAc4Sm8 cuboctahedra. There are four shorter (3.71 Å) and eight longer (3.72 Å) Ac–Sm bond lengths. There are two inequivalent Sm sites. In the first Sm site, Sm is bonded to four equivalent Ac and eight Sm atoms to form SmAc4Sm8 cuboctahedra that share corners with twelve equivalent SmAc4Sm8 cuboctahedra, edges with eight equivalent AcSm12 cuboctahedra, edges with sixteen SmAc4Sm8 cuboctahedra, faces with four equivalent AcSm12 cuboctahedra, and faces with fourteen SmAc4Sm8 cuboctahedra. There are four shorter (3.71 Å) and four longer (3.72 Å) Sm–Sm bond lengths. In the second Sm site, Sm is bonded to four equivalent Ac and eight equivalent Sm atoms to form SmAc4Sm8 cuboctahedra that share corners with four equivalent SmAc4Sm8 cuboctahedra, corners with eight equivalent AcSm12 cuboctahedra, edges with twenty-four SmAc4Sm8 cuboctahedra, faces with six equivalent AcSm12 cuboctahedra, and faces with twelve SmAc4Sm8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AcPm3 by Materials Project

AcPm3 is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ac is bonded to twelve Pm atoms to form AcPm12 cuboctahedra that share corners with four equivalent AcPm12 cuboctahedra, corners with eight equivalent PmAc4Pm8 cuboctahedra, edges with eight equivalent AcPm12 cuboctahedra, edges with sixteen equivalent PmAc4Pm8 cuboctahedra, faces with four equivalent AcPm12 cuboctahedra, and faces with fourteen PmAc4Pm8 cuboctahedra. There are four shorter (3.73 Å) and eight longer (3.74 Å) Ac–Pm bond lengths. There are two inequivalent Pm sites. In the first Pm site, Pm is bonded to four equivalent Ac and eight Pm atoms to form PmAc4Pm8 cuboctahedra that share corners with twelve equivalent PmAc4Pm8 cuboctahedra, edges with eight equivalent AcPm12 cuboctahedra, edges with sixteen PmAc4Pm8 cuboctahedra, faces with four equivalent AcPm12 cuboctahedra, and faces with fourteen PmAc4Pm8 cuboctahedra. There are four shorter (3.73 Å) and four longer (3.74 Å) Pm–Pm bond lengths. In the second Pm site, Pm is bonded to four equivalent Ac and eight equivalent Pm atoms to form PmAc4Pm8 cuboctahedra that share corners with four equivalent PmAc4Pm8 cuboctahedra, corners with eight equivalent AcPm12 cuboctahedra, edges with twenty-four PmAc4Pm8 cuboctahedra, faces with six equivalent AcPm12 cuboctahedra, and faces with twelve PmAc4Pm8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AcNd3 by Materials Project

AcNd3 is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ac is bonded to twelve Nd atoms to form AcNd12 cuboctahedra that share corners with four equivalent AcNd12 cuboctahedra, corners with eight equivalent NdAc4Nd8 cuboctahedra, edges with eight equivalent AcNd12 cuboctahedra, edges with sixteen equivalent NdAc4Nd8 cuboctahedra, faces with four equivalent AcNd12 cuboctahedra, and faces with fourteen NdAc4Nd8 cuboctahedra. All Ac–Nd bond lengths are 3.75 Å. There are two inequivalent Nd sites. In the first Nd site, Nd is bonded to four equivalent Ac and eight Nd atoms to form NdAc4Nd8 cuboctahedra that share corners with twelve equivalent NdAc4Nd8 cuboctahedra, edges with eight equivalent AcNd12 cuboctahedra, edges with sixteen NdAc4Nd8 cuboctahedra, faces with four equivalent AcNd12 cuboctahedra, and faces with fourteen NdAc4Nd8 cuboctahedra. All Nd–Nd bond lengths are 3.75 Å. In the second Nd site, Nd is bonded to four equivalent Ac and eight equivalent Nd atoms to form NdAc4Nd8 cuboctahedra that share corners with four equivalent NdAc4Nd8 cuboctahedra, corners with eight equivalent AcNd12 cuboctahedra, edges with twenty-four NdAc4Nd8 cuboctahedra, faces with six equivalent AcNd12 cuboctahedra, and faces with twelve NdAc4Nd8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AcLa3 by Materials Project

AcLa3 is Magnesium-derived structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Ac is bonded to twelve La atoms to form AcLa12 cuboctahedra that share corners with six equivalent AcLa12 cuboctahedra, corners with twelve LaAc4La8 cuboctahedra, edges with eighteen LaAc4La8 cuboctahedra, faces with eight equivalent AcLa12 cuboctahedra, and faces with twelve LaAc4La8 cuboctahedra. There are six shorter (3.82 Å) and six longer (3.85 Å) Ac–La bond lengths. There are two inequivalent La sites. In the first La site, La is bonded to four equivalent Ac and eight La atoms to form LaAc4La8 cuboctahedra that share corners with four equivalent AcLa12 cuboctahedra, corners with fourteen equivalent LaAc4La8 cuboctahedra, edges with six equivalent AcLa12 cuboctahedra, edges with twelve LaAc4La8 cuboctahedra, faces with four equivalent AcLa12 cuboctahedra, and faces with sixteen LaAc4La8 cuboctahedra. There are a spread of La–La bond distances ranging from 3.75–3.89 Å. In the second La site, La is bonded to four equivalent Ac and eight equivalent La atoms to form LaAc4La8 cuboctahedra that share corners with four equivalent AcLa12 cuboctahedra, corners with fourteen LaAc4La8 cuboctahedra, edges with six equivalent AcLa12 cuboctahedra, edges with twelve equivalent LaAc4La8 cuboctahedra, faces with four equivalent AcLa12 cuboctahedra, and faces with sixteen LaAc4La8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AcNb3 by Materials Project

AcNb3 is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Ac is bonded in a distorted body-centered cubic geometry to fourteen Nb atoms. There are eight shorter (3.06 Å) and six longer (3.53 Å) Ac–Nb bond lengths. There are two inequivalent Nb sites. In the first Nb site, Nb is bonded to four equivalent Ac and four equivalent Nb atoms to form a mixture of distorted face, edge, and corner-sharing NbAc4Nb4 tetrahedra. All Nb–Nb bond lengths are 3.06 Å. In the second Nb site, Nb is bonded in a 8-coordinate geometry to six equivalent Ac and eight equivalent Nb atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AcCe3 by Materials Project

AcCe3 is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ac is bonded to twelve Ce atoms to form AcCe12 cuboctahedra that share corners with four equivalent AcCe12 cuboctahedra, corners with eight equivalent CeAc4Ce8 cuboctahedra, edges with eight equivalent AcCe12 cuboctahedra, edges with sixteen equivalent CeAc4Ce8 cuboctahedra, faces with four equivalent AcCe12 cuboctahedra, and faces with fourteen CeAc4Ce8 cuboctahedra. There are four shorter (3.53 Å) and eight longer (3.54 Å) Ac–Ce bond lengths. There are two inequivalent Ce sites. In the first Ce site, Ce is bonded to four equivalent Ac and eight Ce atoms to form CeAc4Ce8 cuboctahedra that share corners with twelve equivalent CeAc4Ce8 cuboctahedra, edges with eight equivalent AcCe12 cuboctahedra, edges with sixteen CeAc4Ce8 cuboctahedra, faces with four equivalent AcCe12 cuboctahedra, and faces with fourteen CeAc4Ce8 cuboctahedra. There are four shorter (3.53 Å) and four longer (3.54 Å) Ce–Ce bond lengths. In the second Ce site, Ce is bonded to four equivalent Ac and eight equivalent Ce atoms to form CeAc4Ce8 cuboctahedra that share corners with four equivalent CeAc4Ce8 cuboctahedra, corners with eight equivalent AcCe12 cuboctahedra, edges with twenty-four CeAc4Ce8 cuboctahedra, faces with six equivalent AcCe12 cuboctahedra, and faces with twelve CeAc4Ce8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AcPr3 by Materials Project

AcPr3 is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ac is bonded to twelve Pr atoms to form AcPr12 cuboctahedra that share corners with four equivalent AcPr12 cuboctahedra, corners with eight equivalent PrAc4Pr8 cuboctahedra, edges with eight equivalent AcPr12 cuboctahedra, edges with sixteen equivalent PrAc4Pr8 cuboctahedra, faces with four equivalent AcPr12 cuboctahedra, and faces with fourteen PrAc4Pr8 cuboctahedra. There are four shorter (3.77 Å) and eight longer (3.78 Å) Ac–Pr bond lengths. There are two inequivalent Pr sites. In the first Pr site, Pr is bonded to four equivalent Ac and eight Pr atoms to form PrAc4Pr8 cuboctahedra that share corners with twelve equivalent PrAc4Pr8 cuboctahedra, edges with eight equivalent AcPr12 cuboctahedra, edges with sixteen PrAc4Pr8 cuboctahedra, faces with four equivalent AcPr12 cuboctahedra, and faces with fourteen PrAc4Pr8 cuboctahedra. There are four shorter (3.77 Å) and four longer (3.78 Å) Pr–Pr bond lengths. In the second Pr site, Pr is bonded to four equivalent Ac and eight equivalent Pr atoms to form PrAc4Pr8 cuboctahedra that share corners with four equivalent PrAc4Pr8 cuboctahedra, corners with eight equivalent AcPr12 cuboctahedra, edges with twenty-four PrAc4Pr8 cuboctahedra, faces with six equivalent AcPr12 cuboctahedra, and faces with twelve PrAc4Pr8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AcTb3 by Materials Project

AcTb3 is Copper-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ac is bonded to twelve Tb atoms to form AcTb12 cuboctahedra that share corners with four equivalent AcTb12 cuboctahedra, corners with eight equivalent TbAc4Tb8 cuboctahedra, edges with eight equivalent AcTb12 cuboctahedra, edges with sixteen equivalent TbAc4Tb8 cuboctahedra, faces with four equivalent AcTb12 cuboctahedra, and faces with fourteen TbAc4Tb8 cuboctahedra. There are eight shorter (3.67 Å) and four longer (3.68 Å) Ac–Tb bond lengths. There are two inequivalent Tb sites. In the first Tb site, Tb is bonded to four equivalent Ac and eight Tb atoms to form TbAc4Tb8 cuboctahedra that share corners with twelve equivalent TbAc4Tb8 cuboctahedra, edges with eight equivalent AcTb12 cuboctahedra, edges with sixteen TbAc4Tb8 cuboctahedra, faces with four equivalent AcTb12 cuboctahedra, and faces with fourteen TbAc4Tb8 cuboctahedra. There are four shorter (3.67 Å) and four longer (3.68 Å) Tb–Tb bond lengths. In the second Tb site, Tb is bonded to four equivalent Ac and eight equivalent Tb atoms to form TbAc4Tb8 cuboctahedra that share corners with four equivalent TbAc4Tb8 cuboctahedra, corners with eight equivalent AcTb12 cuboctahedra, edges with twenty-four TbAc4Tb8 cuboctahedra, faces with six equivalent AcTb12 cuboctahedra, and faces with twelve TbAc4Tb8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AcY3 by Materials Project

AcY3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ac is bonded to twelve Y atoms to form AcY12 cuboctahedra that share corners with four equivalent AcY12 cuboctahedra, corners with eight equivalent YAc4Y8 cuboctahedra, edges with eight equivalent AcY12 cuboctahedra, edges with sixteen equivalent YAc4Y8 cuboctahedra, faces with four equivalent AcY12 cuboctahedra, and faces with fourteen YAc4Y8 cuboctahedra. There are eight shorter (3.69 Å) and four longer (3.70 Å) Ac–Y bond lengths. There are two inequivalent Y sites. In the first Y site, Y is bonded to four equivalent Ac and eight Y atoms to form YAc4Y8 cuboctahedra that share corners with twelve equivalent YAc4Y8 cuboctahedra, edges with eight equivalent AcY12 cuboctahedra, edges with sixteen YAc4Y8 cuboctahedra, faces with four equivalent AcY12 cuboctahedra, and faces with fourteen YAc4Y8 cuboctahedra. There are four shorter (3.69 Å) and four longer (3.70 Å) Y–Y bond lengths. In the second Y site, Y is bonded to four equivalent Ac and eight equivalent Y atoms to form YAc4Y8 cuboctahedra that share corners with four equivalent YAc4Y8 cuboctahedra, corners with eight equivalent AcY12 cuboctahedra, edges with twenty-four YAc4Y8 cuboctahedra, faces with six equivalent AcY12 cuboctahedra, and faces with twelve YAc4Y8 cuboctahedra.

36 MATERIALS SCIENCE↗