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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.

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At least 1,063 records · Page 59
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Analysis of two-dimensional incompressible flow past airfoils using unsteady Navier-Stokes equations

The conservative form of the unsteady Navier-Stokes equations in terms of vorticity and stream function in generalized curvilinear coordinates are used to analyze the flow structure of steady separation and unsteady flow with massive separation. The numerical method solves the discretized equations using an ADI-BGE method. The method is applied to a symmetric 12 percent thick Joukowski airfoil. A conformal clustered grid is generated; several 1-D stretching transformations are used to obtain a grid that attempts to resolve many of the multiple scales of the unsteady flow with massive separation, while maintaining the transformation metrics to be smooth and continuous in the entire flow field. Detailed numerical results are obtained for three flow configurations (1) Re = 1000, alpha = 5 deg, (2) Re = 1000, alpha = 15 deg, (3) Re = 10,000, alpha = 5 deg. No artificial dissipation was added; however, lack of a fine grid in the normal direction has presently led to results which are considered qualitative, especially for case (3).

Ghia, K. N.↗
NASA NTRS1986

Analysis of two-dimensional incompressible flow past airfoils using unsteady Navier-Stokes equations

The conservative form of the unsteady Navier-Stokes equations in terms of vorticity and stream function in generalized curvilinear coordinates are used to analyze the flow structure of steady separation and unsteady flow with massive separation. The numerical method solves the discretized equations using an ADI-BGE method. The method is applied to a symmetric 12 percent thick Joukowski airfoil. A conformal clustered grid is generated; several 1-D stretching transformations are used to obtain a grid that attempts to resolve many of the multiple scales of the unsteady flow with massive separation, while maintaining the transformation metrics to be smooth and continuous in the entire flow field. Detailed numerical results are obtained for three flow configurations (1) Re = 1000, alpha = 5 deg., (2) Re =1000, alpha = 15 deg., (3) Re = 10,000, alpha = 5 deg. No artificial dissipation was added; however, lack of a fine grid in the normal direction has presently led to results which are considered qualitative, especially for case (3).

Ghia, K. N.↗
NASA NTRS1987

The focal plane reception pattern calculation for a paraboloidal antenna with a nearby fence

A computer simulation program is described which is used to estimate the effects of a proximate diffraction fence on the performance of paraboloid antennas. The computer program is written in FORTRAN. The physical problem, mathematical formulation and coordinate references are described. The main control structure of the program and the function of the individual subroutines are discussed. The Job Control Language set-up and program instruction are provided in the user's instruction to help users execute the present program. A sample problem with an appropriate output listing is made available as an illustration of the usage of the program.

Schmidt, Richard F.↗
NASA NTRS1987

Software and hardware for intelligent robots

Various architectures and their respective software for Hierarchically Intelligent Robots are discussed. They conform to the Principle of Increasing Precision with Decreasing Intelligence by following a three-level structure. The architecture of the organization and coordination levels is presented here and their algorithms are outlined.

Saridis, G. N.↗
NASA NTRS1996

Multidisciplinary Design Of Hot Composite Structures

Unified computer code developed to implement multidisciplinary approach to design and analysis of composite-material structures that must withstand high temperatures. Code modular: includes executive module communicating with and coordinating other modules performing calculations pertaining to traditionally separate disciplines like those of acoustics, structural vibrations, structural loads, and thermal effects. Essential feature, finite-element numerical simulation of relevant physical phenomena according to applicable disciplines. Same finite-element mesh used in thermal, vibrational, and structural analyses; minimizing data-preparation time and eliminating errors incurred in transforming temperatures from one finite-element mesh to another.

Chamis, Christos C.↗
NASA NTRS1999

Advances in Understanding Decadal Climate Variability

Recently, a joint Brazil-France-U.S. program, known as PIRATA (Pilot Research moored Array in the Tropical Atlantic), was proposed to begin the deployment of moored measurement platforms in the tropical Atlantic in order to enhance the existing observational data base and subsequent understanding of the processes by which the ocean and atmosphere couple in key regions of the tropical Atlantic Ocean. Empirical studies have suggested that there are strong relationships between tropical Atlantic upper ocean variability, SST, ocean-atmosphere coupling and regional climate variability. During the early 1980's a coordinated set of surface wind, subsurface thermal structure, and subsurface current observations were obtained as part of the U.S.-France SEQUAL-FOCAL process experiment designed to observe the seasonal response of the tropical Atlantic Ocean to surface forcing. Since that time, however, the observational data base for the tropical Atlantic Ocean has disintegrated to a few ship-tracks measuring ocean temperatures and a small collection of tide gauge stations measuring sea level. A more comprehensive set of observations, modeling and empirical studies is now in order to make progress on understanding the regional climate variability. The proposed PIRATA program will use mooring platforms similar to the tropical Pacific Ocean TAO array to measure surface fluxes of momentum and heat and the corresponding changes in the upper ocean thermal structure. It is anticipated that the oceanic data from this monitoring array will also be used in a predictive mode for initialization studies of regional coupled climate models. Of particular interest are zonal and meridional modes of ocean-atmosphere variability within the tropical Atlantic basin that have significant impacts on the regional climate of the bordering continents.

Busalacchi, Antonio J.↗
NASA NTRS1998

Advances in Understanding Decadal Climate Variability

Recently, a joint Brazil-France-U.S. program, known as PIRATA (Pilot Research moored Array in the Tropical Atlantic), was proposed to begin the deployment of moored measurement platforms in the tropical Atlantic in order to enhance the existing observational data base and subsequent understanding of the processes by which the ocean and atmosphere couple in key regions of the tropical Atlantic Ocean. Empirical studies have suggested that there are strong relationships between tropical Atlantic upper ocean variability, SST, ocean-atmosphere coupling and regional climate variability. During the early 1980's a coordinated set of surface wind, subsurface thermal structure, and subsurface current observations were obtained as part of the U.S.-France SEQUAL- FOCAL process experiment designed to observe the seasonal response of the tropical Atlantic Ocean to surface forcing. Since that time, however, the observational data base for the tropical Atlantic Ocean has disintegrated to a few shiptracks measuring ocean temperatures and a small collection of tide gauge stations measuring sea level. A more comprehensive set of observations, modeling and empirical studies is now in order to make progress on understanding the regional climate variability. The proposed PIRATA program will use mooring platforms similar to the tropical Pacific Ocean TAO array to measure surface fluxes of momentum and heat and the corresponding changes in the upper ocean thermal structure. It is anticipated that the oceanic data from this monitoring array will also be used in a predictive mode for initialization studies of regional coupled climate models. Of particular interest are zonal and meridional modes of ocean-atmosphere variability within the tropical Atlantic basin that have significant impacts on the regional climate of the bordering continents.

Busalaacchi, Antonio J.↗
NASA NTRS2008

Construction of Penrose Diagrams for Dynamic Black Holes

A set of Penrose diagrams is constructed in order to examine the large-scale causal structure of black holes with dynamic horizons. Coordinate dependencies of significant features, such as the event horizon and radial mass scale, are demonstrated on the diagrams. Unlike in static Schwarzschild geometries, the radial mass scale is clearly seen to differ from the horizon. Trajectories for photons near the horizon are briefly discussed.

Brown, Beth A.↗
NASA NTRS2009

An Overview of the NASA FAP Hypersonics Project Airbreathing Propulsion Research

The propulsion research portfolio of the National Aeronautics and Space Administration Fundamental Aeronautics Program Hypersonics Project encompasses a significant number of technical tasks that are aligned to achieve mastery and intellectual stewardship of the core competencies in the hypersonic-flight regime. An overall coordinated programmatic and technical effort has been structured to advance the state-of-the-art, via both experimental and analytical efforts. A subset of the entire hypersonics propulsion research portfolio is presented in this overview paper. To this end, two programmatic research disciplines are discussed; namely, (1) the Propulsion Discipline, including three associated research elements: the X-51A partnership, the HIFiRE-2 partnership, and the Durable Combustor Rig, and (2) the Turbine-Based Combine Cycle Discipline, including three associated research elements: the Combined Cycle Engine Large Scale Inlet Mode Transition Experiment, the small-scale Inlet Mode Transition Experiment, and the High-Mach Fan Rig.

Auslender, A. H.↗
NASA NTRS2007

Science Archives in the 21st Century: A NASA LAMBDA Report

Lambda is a thematic data center that focuses on serving the cosmic microwave background (CMB) research community. LAMBDA is an active archive for NASA's Cosmic Background Explorer (COBE) and Wilkinson Microwave Anisotropy Probe (WMAP) mission data sets. In addition, LAMBDA provides analysis software, on-line tools, relevant ancillary data and important web links. LAMBDA also tries to preserve the most important ground-based and suborbital CMB data sets. CMB data is unlike other astrophysical data, consisting of intrinsically diffuse surface brightness photometry with a signal contrast of the order 1 part in 100,000 relative to the uniform background. Because of the extremely faint signal levels, the signal-to-noise ratio is relatively low and detailed instrument-specific knowledge of the data is essential. While the number of data sets being produced is not especially large, those data sets are becoming large and complex. That tendency will increase when the many polarization experiments currently being deployed begin producing data. The LAMBDA experience supports many aspects of the NASA data archive model developed informally over the last ten years-that small focused data centers are often more effective than larger more ambitious collections, for example; that data centers are usually best run by active scientists; that it can be particularly advantageous if those scientists are leaders in the use of the archived data sets; etc. LAMBDA has done some things so well that they might provide lessons for other archives. A lot of effort has been devoted to developing a simple and consistent interface to data sets, for example; and serving all the documentation required via simple 'more' pages and longer explanatory supplements. Many of the problems faced by LAMBDA will also not surprise anyone trying to manage other space science data. These range from persuading mission scientists to provide their data as quickly as possible, to dealing with a high volume of nuisance (spam) messages. Because so many data center problems and solutions are common across individual data centers and disciplines it would be very valuable to establish some new systems of communication - such as informal email lists for administrators and developers. But resources are very limited, so new timeconsuming and inefficient mechanisms - like too-frequent and too-structured meetingsshould be avoided. Although there are great advantages to being small, agile and independent, there are also some areas where science data centers within and without NASA could be better coordinated - for the assignment of persistent identifiers; to encourage the early adoption of useful standards and technologies; etc. Some super-structure to facilitate such coordination might be beneficial as long as it doesn't begin to control the other work of the archives, and become a "methodology police". In this respect the CCSDS "Reference Model for an Open Archive Information System" is a little worrying. It may be that the closer a data center gets to following such a detailed prescription, the less effective it will become. It is much better to have an informal coordination process than a bureaucratic straight-jacket.

Butterworth, P.↗
DOE OSTI2020

Materials Data on NdTa7O19 by Materials Project

NdTa7O19 crystallizes in the hexagonal P-6c2 space group. The structure is three-dimensional. Nd3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are six shorter (2.46 Å) and two longer (2.66 Å) Nd–O bond lengths. There are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ta–O bond distances ranging from 1.93–2.49 Å. In the second Ta5+ site, Ta5+ is bonded in an octahedral geometry to six equivalent O2- atoms. All Ta–O bond lengths are 2.01 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to three equivalent Ta5+ atoms. In the second O2- site, O2- is bonded in a 4-coordinate geometry to one Nd3+ and three equivalent Ta5+ atoms. In the third O2- site, O2- is bonded in a trigonal planar geometry to three equivalent Ta5+ atoms. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Ta5+ atoms. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Nd3+ and two Ta5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NdP2H9O10 by Materials Project

NdP2H9O10 crystallizes in the orthorhombic Pnna space group. The structure is three-dimensional. Nd3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Nd–O bond distances ranging from 2.43–2.51 Å. P5+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There are a spread of P–O bond distances ranging from 1.53–1.57 Å. There are five inequivalent H+0.78+ sites. In the first H+0.78+ site, H+0.78+ is bonded in a linear geometry to two equivalent O2- atoms. Both H–O bond lengths are 1.21 Å. In the second H+0.78+ site, H+0.78+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the third H+0.78+ site, H+0.78+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fourth H+0.78+ site, H+0.78+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fifth H+0.78+ site, H+0.78+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a water-like geometry to one Nd3+ and two H+0.78+ atoms. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one P5+ and one H+0.78+ atom. In the third O2- site, O2- is bonded in a water-like geometry to one Nd3+ and two H+0.78+ atoms. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to one Nd3+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to one Nd3+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KTa5O13 by Materials Project

KTa5O13 crystallizes in the orthorhombic Pbcm space group. The structure is three-dimensional. K1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of K–O bond distances ranging from 2.73–3.11 Å. There are three inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form a mixture of distorted edge and corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 51–55°. There are a spread of Ta–O bond distances ranging from 1.93–2.22 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 14–45°. There are a spread of Ta–O bond distances ranging from 1.93–2.12 Å. In the third Ta5+ site, Ta5+ is bonded to six O2- atoms to form a mixture of distorted edge and corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 32–55°. There are a spread of Ta–O bond distances ranging from 1.89–2.23 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two Ta5+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to three Ta5+ atoms. In the third O2- site, O2- is bonded in a 3-coordinate geometry to three Ta5+ atoms. In the fourth O2- site, O2- is bonded in a distorted linear geometry to one K1+ and two equivalent Ta5+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+ and two Ta5+ atoms. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+ and two Ta5+ atoms. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one K1+ and two Ta5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaLi5Sn4 by Materials Project

NaLi5Sn4 crystallizes in the trigonal R3m space group. The structure is three-dimensional. Na is bonded in a 10-coordinate geometry to seven Li and three equivalent Sn atoms. There are a spread of Na–Li bond distances ranging from 2.90–3.19 Å. All Na–Sn bond lengths are 3.22 Å. There are five inequivalent Li sites. In the first Li site, Li is bonded in a 4-coordinate geometry to three equivalent Na, one Li, and four Sn atoms. The Li–Li bond length is 2.72 Å. There are one shorter (2.85 Å) and three longer (3.02 Å) Li–Sn bond lengths. In the second Li site, Li is bonded in a 3-coordinate geometry to one Li and three equivalent Sn atoms. All Li–Sn bond lengths are 3.10 Å. In the third Li site, Li is bonded to one Na and four Sn atoms to form distorted corner-sharing LiNaSn4 tetrahedra. There are three shorter (2.98 Å) and one longer (3.09 Å) Li–Sn bond lengths. In the fourth Li site, Li is bonded in a distorted body-centered cubic geometry to three equivalent Na, one Li, and four Sn atoms. The Li–Li bond length is 2.63 Å. There are one shorter (2.79 Å) and three longer (3.04 Å) Li–Sn bond lengths. In the fifth Li site, Li is bonded in a 3-coordinate geometry to one Li and six Sn atoms. There are three shorter (3.12 Å) and three longer (3.29 Å) Li–Sn bond lengths. There are four inequivalent Sn sites. In the first Sn site, Sn is bonded in a 11-coordinate geometry to three equivalent Na, seven Li, and one Sn atom. The Sn–Sn bond length is 2.84 Å. In the second Sn site, Sn is bonded in a distorted body-centered cubic geometry to four Li and four Sn atoms. All Sn–Sn bond lengths are 3.03 Å. In the third Sn site, Sn is bonded in a distorted trigonal non-coplanar geometry to three equivalent Li and four Sn atoms. The Sn–Sn bond length is 2.93 Å. In the fourth Sn site, Sn is bonded in a 7-coordinate geometry to seven Li and one Sn atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TlSb3S5 by Materials Project

TlSb3S5 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Tl1+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are a spread of Tl–S bond distances ranging from 3.09–3.75 Å. There are three inequivalent Sb3+ sites. In the first Sb3+ site, Sb3+ is bonded in a distorted rectangular see-saw-like geometry to four S2- atoms. There are a spread of Sb–S bond distances ranging from 2.46–3.11 Å. In the second Sb3+ site, Sb3+ is bonded to five S2- atoms to form distorted edge-sharing SbS5 square pyramids. There are a spread of Sb–S bond distances ranging from 2.46–3.17 Å. In the third Sb3+ site, Sb3+ is bonded in a distorted see-saw-like geometry to four S2- atoms. There are a spread of Sb–S bond distances ranging from 2.48–3.05 Å. There are five inequivalent S2- sites. In the first S2- site, S2- is bonded in a 2-coordinate geometry to two equivalent Tl1+ and three Sb3+ atoms. In the second S2- site, S2- is bonded to two equivalent Tl1+ and two Sb3+ atoms to form distorted corner-sharing STl2Sb2 tetrahedra. In the third S2- site, S2- is bonded in a 2-coordinate geometry to two equivalent Tl1+ and two Sb3+ atoms. In the fourth S2- site, S2- is bonded in a 3-coordinate geometry to one Tl1+ and two Sb3+ atoms. In the fifth S2- site, S2- is bonded in a 5-coordinate geometry to one Tl1+ and four Sb3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaSb5O8 by Materials Project

NaSb5O8 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Na1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Na–O bond distances ranging from 2.36–3.01 Å. There are five inequivalent Sb3+ sites. In the first Sb3+ site, Sb3+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Sb–O bond distances ranging from 1.98–2.67 Å. In the second Sb3+ site, Sb3+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are a spread of Sb–O bond distances ranging from 1.99–2.31 Å. In the third Sb3+ site, Sb3+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of Sb–O bond distances ranging from 2.01–2.29 Å. In the fourth Sb3+ site, Sb3+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are a spread of Sb–O bond distances ranging from 1.98–2.71 Å. In the fifth Sb3+ site, Sb3+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are a spread of Sb–O bond distances ranging from 2.00–2.52 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Na1+ and two Sb3+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to three Sb3+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Na1+ and two Sb3+ atoms. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+ and three Sb3+ atoms. In the fifth O2- site, O2- is bonded to two equivalent Na1+ and two Sb3+ atoms to form distorted edge-sharing ONa2Sb2 tetrahedra. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to four Sb3+ atoms. In the seventh O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Na1+ and two Sb3+ atoms. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and three Sb3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TlI3 by Materials Project

TlI3 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Tl3+ is bonded in a 5-coordinate geometry to five I1- atoms. There are a spread of Tl–I bond distances ranging from 3.63–3.76 Å. There are three inequivalent I1- sites. In the first I1- site, I1- is bonded in a 2-coordinate geometry to two I1- atoms. There are one shorter (2.88 Å) and one longer (3.03 Å) I–I bond lengths. In the second I1- site, I1- is bonded in a 1-coordinate geometry to four equivalent Tl3+ and one I1- atom. In the third I1- site, I1- is bonded in a 2-coordinate geometry to one Tl3+ and one I1- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ThTa2O7 by Materials Project

ThTa2O7 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Th4+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Th–O bond distances ranging from 2.40–2.85 Å. There are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form distorted TaO6 octahedra that share corners with two equivalent TaO6 octahedra, a cornercorner with one TaO7 pentagonal bipyramid, an edgeedge with one TaO6 octahedra, and an edgeedge with one TaO7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 22°. There are a spread of Ta–O bond distances ranging from 1.93–2.12 Å. In the second Ta5+ site, Ta5+ is bonded to seven O2- atoms to form TaO7 pentagonal bipyramids that share a cornercorner with one TaO6 octahedra, corners with two equivalent TaO7 pentagonal bipyramids, an edgeedge with one TaO6 octahedra, and an edgeedge with one TaO7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 39°. There are a spread of Ta–O bond distances ranging from 1.98–2.21 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to three Ta5+ atoms. In the second O2- site, O2- is bonded in a distorted water-like geometry to two equivalent Th4+ and two equivalent Ta5+ atoms. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Th4+ and two equivalent Ta5+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Th4+ and two equivalent Ta5+ atoms. In the fifth O2- site, O2- is bonded to three equivalent Th4+ and one Ta5+ atom to form a mixture of distorted edge and corner-sharing OTh3Ta tetrahedra. In the sixth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two equivalent Th4+ and one Ta5+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Th4+ and two Ta5+ atoms.

36 MATERIALS SCIENCE↗