Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “PN ranging”

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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on CuW3Cl7 by Materials Project

W3CuCl7 crystallizes in the cubic Pn-3 space group. The structure is three-dimensional. W2+ is bonded to five Cl1- atoms to form edge-sharing WCl5 square pyramids. There are a spread of W–Cl bond distances ranging from 2.49–2.52 Å. Cu1+ is bonded in a trigonal planar geometry to three equivalent Cl1- atoms. All Cu–Cl bond lengths are 2.26 Å. There are three inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 3-coordinate geometry to three equivalent W2+ atoms. In the second Cl1- site, Cl1- is bonded in a bent 120 degrees geometry to one W2+ and one Cu1+ atom. In the third Cl1- site, Cl1- is bonded in a 12-coordinate geometry to three equivalent W2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuMo3Cl7 by Materials Project

Mo3CuCl7 crystallizes in the cubic Pn-3 space group. The structure is three-dimensional. Mo2+ is bonded to five Cl1- atoms to form edge-sharing MoCl5 square pyramids. There are a spread of Mo–Cl bond distances ranging from 2.48–2.50 Å. Cu1+ is bonded in a trigonal planar geometry to three equivalent Cl1- atoms. All Cu–Cl bond lengths are 2.26 Å. There are three inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 3-coordinate geometry to three equivalent Mo2+ atoms. In the second Cl1- site, Cl1- is bonded in a 3-coordinate geometry to three equivalent Mo2+ atoms. In the third Cl1- site, Cl1- is bonded in a bent 120 degrees geometry to one Mo2+ and one Cu1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuMo3Br7 by Materials Project

Mo3CuBr7 crystallizes in the cubic Pn-3 space group. The structure is three-dimensional. Mo2+ is bonded to five Br1- atoms to form edge-sharing MoBr5 square pyramids. There are a spread of Mo–Br bond distances ranging from 2.62–2.66 Å. Cu1+ is bonded in a trigonal planar geometry to three equivalent Br1- atoms. All Cu–Br bond lengths are 2.40 Å. There are three inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a 12-coordinate geometry to three equivalent Mo2+ atoms. In the second Br1- site, Br1- is bonded in a bent 120 degrees geometry to one Mo2+ and one Cu1+ atom. In the third Br1- site, Br1- is bonded in a 12-coordinate geometry to three equivalent Mo2+ atoms.

36 MATERIALS SCIENCE↗
NASA NTRS2005

Measurements of Breakdown Field and Forward Current Stability in 3C-SiC P-N Junction Diodes Grown on Step-Free 4H-SiC

This paper reports on initial fabrication and electrical characterization of 3C-SiC p-n junction diodes grown on step-free 4H-SiC mesas. Diodes with n-blocking-layer doping ranging from approx. 2 x 10(exp 16)/cu cm to approx.. 5 x 10(exp 17)/cu cm were fabricated and tested. No optimization of junction edge termination or ohmic contacts was employed. Room temperature reverse characteristics of the best devices show excellent low-leakage behavior, below previous 3C-SiC devices produced by other growth techniques, until the onset of a sharp breakdown knee. The resulting estimated breakdown field of 3C-SiC is at least twice the breakdown field of silicon, but is only around half the breakdown field of <0001> 4H-SiC for the doping range studied. Initial high current stressing of 3C diodes at 100 A/sq cm for more than 20 hours resulted in less than 50 mV change in approx. 3 V forward voltage. 3C-SiC, pn junction, p+n diode, rectifier, reverse breakdown, breakdown field,heteroepitaxy, epitaxial growth, electroluminescence, mesa, bipolar diode

Neudeck, Philip G.↗
NASA NTRS1983

Development of ion-implantation confined, shallow mesa stripe (Pn,Sn)Te/Pb(Te,Se) DH laser diodes

Preliminary results of a program to develop ion implantation confined, shallow mesa stripe (Pb,Sn)Te laser diodes are presented. The practicality of using a shallow mesa stripe to produce single mode laser output and to increase the single mode tuning range are demonstrated. The first results of p-type ion implantation in the lead-tin salts are also reported. It is shown that sodium and lithium both can be used to convert n-type Pb(Te,Se) to p-type. The implant and anneal procedures are described, and electrical characteristics of Li-implanted layers are presented.

Fonstad, C. G.↗
NASA NTRS2019

Design of P-3 Nadir Port

This project details the design and analysis of a structure to replace the interface of the P-3B nadir port with an optimized interface for science installations. A new nadir port plug has been designed to replace the OEM (Original Equipment Manufacturer) plug (Lockheed PN 910169) currently used in Nadir ports 1 and 2 on the NASA P-3B aircraft. The plug consists of a milled frame that can be outfitted with customizable flat plates to meet a broad range of science needs. The frame slides into place using the existing P-3B rail system using a lever and tie-rod assembly. The seal interface will contact the Fuselage skin of the aircraft and consists of a bulb E-seal that is riveted around the perimeter of the frame. The flat plate (20 inches x 31 inches) provides a large profile that can be outfitted based on science mission goals and requirements to attach multiple instruments. This is a significant increase to the aircraft capability. Previously, the OEM plug had to be modified to hold very small plates, windows, or instruments limiting the use of the ports.There were several challenges for this project that included a constrained schedule, lack of historical references, and reverse engineering. The unusually tight schedule for design, manufacture, and install limited potential approaches. In addition, design of a new interface to replace the existing plug, on an aircraft designed in the 1960's by Lockheed for the Navy with little to no documentation, required substantial reverse engineering. In order to accomplish this, a suitable method to determine interface requirements with the aircraft had to be solved. After several iterations, the solution was to implement laser scanning techniques to scan the aircraft and the OEM plug and generate a 3D model to capture the design envelope. The structure is designed to maintain a positive margin of safety when subjected to the inertial, pressure, and aerodynamic load requirements for an external installation on the P-3B, as described in the Wallops' P-3B Design Requirements 548-RQMT-0001 Rev. A . A finite element model is created in FEMAP (Finite Element Modeling And Postprocessing) and is run through NX Nastran solver to analyze the structure. After several iterations of analysis, the structure was enveloped to hold 115 pounds evenly distributed on the plate.

Chance, Monica↗
DOE OSTI2023

New Trick for an Old Dog: From Prediction to Properties of “Hidden Clathrates” Ba 2 Zn 5 As 6 and Ba 2 Zn 5 Sb 6

The zinc–antimony phase space has been heavily investigated due to the structural complexity and abundance of high-performing thermoelectric materials. Consequentially, the desire to use zinc and antimony as framework elements to encage rattling cations and achieve phonon-glass-electron-crystal-type properties has remained an enticing goal with only two alkali metal clathrates to date, Cs 8 Zn 18 Sb 28 and K 58 Zn 122 Sb 207 . Guided by Zintl electron-counting predictions, here we explored the Ba–Zn–Pn (Pn = As, Sb) phase space proximal to the expected composition of the type-I clathrate. In situ powder X-ray diffraction studies revealed two “hidden” compounds which can only be synthesized in a narrow temperature range. The ex situ synthesis and crystal growth unveiled that instead of type-I clathrates, compositionally close but structurally different new clathrate-like compounds formed, Ba 2 Zn 5 As 6 and Ba 2 Zn 5 Sb 6 . These materials crystallize in a unique structure, in the orthorhombic space group Pmna with the Wyckoff sequence i 2 h 6 gfe. Single-phase synthesis enabled the exploration of their transport properties. Rattling of the Ba cations in oversized cages manifested low thermal conductivity, which, coupled with the high Seebeck coefficients observed, are prerequisites for a promising thermoelectric material. Potential for further optimization of the thermoelectric performance by aliovalent doping was computationally analyzed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1994

The spectrum of the variable planetary nebula IC 4997

The compact, dusty, presumably young planetary nebula (PN) IC 4997 has been studied extensively since the variability of the lambda 4363/lambda 4340 ratio was established in 1956. Since 1938, other nebular lines have shown changes. IC 4997 is also unique because of the great density range revealed by its spectrum which goes in excitation from Mg I to (Ar IV). We present a detailed listing of spectral lines from 360 to 1005 nm. The diagnostic diagram shows that the spectrum can be interpreted only in terms of strata with a huge density gamut. Essential spectral features can be reproduced approximately by a model consisting of a geometrically thin shell of density around 10(exp 7) atoms cm(exp -3), surrounded by a much larger shell with a density of about 10(exp 4) atoms cm(exp -3). The actual, certainly more complex structure can be evaluated only when high resolution spatial imaging is at hand. The usual method of getting abundances from N(ion)/N(H(+)) and ionization correction factors (ICFs) cannot be applied here. It is argued that a reasonable theoretical model that represents the spectrum provides a valid initial approximation to nebular abundances. We propose that the chemical composition of IC 4997 does not differ greatly from that of the Sun. The finally adopted model suggests that the ejection of the material destined to form the inner shell occurred between 1900 and 1960, but observational evidence of such an ejection event is lacking. Perhaps the shell was accelerated. A need for further study is emphasized, especially the role of dust which appears to contribute 2% of the total mass. More attention to this object is recommended. An accurate measurement of its distance is especially desirable.

Hyung, Siek↗
DOE OSTI2020

Materials Data on W3Br7 by Materials Project

W3Br7 is Copper structured and crystallizes in the cubic Pn-3 space group. The structure is zero-dimensional and consists of four W3Br7 clusters. W+2.33+ is bonded to five Br1- atoms to form edge-sharing WBr5 square pyramids. There are a spread of W–Br bond distances ranging from 2.55–2.66 Å. There are three inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a 6-coordinate geometry to three equivalent W+2.33+ atoms. In the second Br1- site, Br1- is bonded in a 12-coordinate geometry to three equivalent W+2.33+ atoms. In the third Br1- site, Br1- is bonded in a single-bond geometry to one W+2.33+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Magnetic Properties Tuning via Broad Range Site Deficiency in Square Net Material UCu x Bi 2

HfCuSi 2 -type pnictogen compounds have recently been shown to be a versatile platform for designing materials with topologically nontrivial band structures. However, these phases require strict control over the electron count to tune the Fermi level, which can only be achieved in compositions with A 2+ M 2+ Pn 2 and A 3+ M + Pn 2 (A = lanthanides, M = transition metals, Pn = pnictogens P–Bi) charge distribution. While such lanthanide compounds have been thoroughly studied as candidate magnetic topological materials, their heavy element analogs with uranium and bismuth remain largely underexplored. In this report, we present the synthesis of UCu x Bi 2 single crystals and study their magnetic properties. Detailed structural analysis revealed that flux-grown crystals always form as a site-deficient UCu x Bi 2 composition, where x varies between 0.20 and 0.64. Magnetic property measurements revealed a dependence of the magnetic coupling on the Cu site deficiency, linearly changing the Néel temperature from 51 K for UCu 0.60 Bi 2 to 118 K for UCu 0.30 Bi 2 . Moreover, higher Cu concentration promotes a metamagnetic transition in highly magnetically anisotropic UCu 0.60 Bi 2 single crystals. We show that DFT calculations can successfully model site deficiency in the UCu x Sb 2 and UCu x Bi 2 systems. This work paves the way toward using the site deficiency to tune the Fermi level in more ubiquitous A 3+ M 2+ x Pn 2 phases, which previously have not been considered topological candidate materials due to unfavorable electron count.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on La3Ru3O11 by Materials Project

La3Ru3O11 crystallizes in the cubic Pn-3 space group. The structure is three-dimensional. there are two inequivalent La3+ sites. In the first La3+ site, La3+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of La–O bond distances ranging from 2.34–2.92 Å. In the second La3+ site, La3+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are two shorter (2.40 Å) and six longer (2.56 Å) La–O bond lengths. Ru+4.33+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing RuO6 octahedra. The corner-sharing octahedral tilt angles are 56°. There are a spread of Ru–O bond distances ranging from 1.96–2.03 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to four La3+ atoms to form OLa4 tetrahedra that share a cornercorner with one OLa4 tetrahedra, corners with nine equivalent OLa2Ru2 trigonal pyramids, edges with three equivalent OLa4 tetrahedra, and edges with three equivalent OLa2Ru2 trigonal pyramids. In the second O2- site, O2- is bonded in a distorted water-like geometry to two equivalent La3+ and two equivalent Ru+4.33+ atoms. In the third O2- site, O2- is bonded to two La3+ and two equivalent Ru+4.33+ atoms to form distorted OLa2Ru2 trigonal pyramids that share corners with three equivalent OLa4 tetrahedra, corners with nine equivalent OLa2Ru2 trigonal pyramids, an edgeedge with one OLa4 tetrahedra, and edges with two equivalent OLa2Ru2 trigonal pyramids.

36 MATERIALS SCIENCE↗
NASA NTRS1981

Minus 55 to plus 200 deg C 12 bit analog-to-digital converter

A 12 bit successive approximation analog to digital converter that offers moderately high speed precision data conversion at a reasonable level of cost and complexity is studied. The ADCH10HT extends this capability over a temperature range of -55 to +200 C. No missing-code performance is maintained over the entire temperature range. The converter is completely self-contained with internal clock and +10 volt reference. The CMOS devices offer low power dissipation, so that the internal temperature of the hybrid circuit does not rise as much from self heating. In CMOS circuits, pn junction leakage currents are returned to the supplies so that the logic keeps working at temperatures up to 250 C.

Smith, L. R.↗
NASA NTRS1999

Study of Bulk and Elementary Screw Dislocation Assisted Reverse Breakdown in Low-Voltage (< 250 V) 4H-SiC p(sup +)n Junction Diodes--Part II: Dynamic Breakdown Properties: Dynamic Breakdown Properties - Part 2

This paper outlines the dynamic reverse-breakdown characteristics of low-voltage (<250 V) small-area <5 x 10(exp -4) sq cm 4H-SiC p(sup +)n diodes subjected to nonadiabatic breakdown-bias pulsewidths ranging from 0.1 to 20 microseconds. 4H-SiC diodes with and without elementary screw dislocations exhibited positive temperature coefficient of breakdown voltage and high junction failure power densities approximately five times larger than the average failure power density of reliable silicon pn rectifiers. This result indicates that highly reliable low-voltage SiC rectifiers may be attainable despite the presence of elementary screw dislocations. However, the impact of elementary screw dislocations on other more useful 4H-SiC power device structures, such as high-voltage (>1 kV) pn junction and Schottky rectifiers, and bipolar gain devices (thyristors, IGBT's, etc.) remains to be investigated.

Neudeck, Philip G.↗
NASA NTRS1985

Kinematics of a large-scale intraplate extending lithosphere: The Basin-Range

Upper lithospheric structure of the Cordilleran Basin Range (B-R) is characterised by an E-W symmetry of velocity layering. The crust is 25 km thick on its eastern active margin, thickening to 30 km within the central portion and thinning to approx. 25 km on the west. Pn velocities of 7.8 to 7.9 km/s characterize the upper mantle low velocity cushion, 7.4 km/s to 7.5 km/s, occurs at a depth of approx. 25 km in the eastern B-R and underlies the area of active extension. An upper-crustal low-velocity zone in the eastern B-R shows a marked P-wave velocity inversion of 7% at depths of 7 to 10 km also in the area of greatest extension. The seismic velocity models for this region of intraplate extension suggest major differences from that of a normal, thermally underformed continental lithosphere. Interpretations of seismic reflection data demonstrate the presence of extensive low-angle reflections in the upper-crust of the eastern B-R at depths from near-surface to 7 to 10 km. These reflections have been interpreted to represent low-angle normal fault detachments or reactivated thrusts. Seismic profiles across steeply-dipping normal faults in unconsolidated sediments show reflections from both planar to downward flatening (listric) faults that in most cases do not penetrate the low-angle detachments. These faults are interpreted as late Cenozoic and cataclastic mylonitic zones of shear displacement.

Smith, R. B.↗
DOE OSTI2020

Materials Data on Y4CdMo3O16 by Materials Project

Y4CdMo3O16 crystallizes in the cubic Pn-3 space group. The structure is three-dimensional. there are two inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Y–O bond distances ranging from 2.30–2.53 Å. In the second Y3+ site, Y3+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are two shorter (2.28 Å) and six longer (2.48 Å) Y–O bond lengths. Mo6+ is bonded in a tetrahedral geometry to four O2- atoms. There is two shorter (1.79 Å) and two longer (1.82 Å) Mo–O bond length. Cd2+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are two shorter (2.26 Å) and six longer (2.61 Å) Cd–O bond lengths. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to two Y3+ and one Mo6+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to one Y3+, one Mo6+, and one Cd2+ atom. In the third O2- site, O2- is bonded to three equivalent Y3+ and one Cd2+ atom to form OY3Cd tetrahedra that share corners with four equivalent OY3Cd tetrahedra and edges with three equivalent OY4 tetrahedra. In the fourth O2- site, O2- is bonded to four Y3+ atoms to form OY4 tetrahedra that share corners with four equivalent OY4 tetrahedra and edges with three equivalent OY3Cd tetrahedra.

36 MATERIALS SCIENCE↗
NASA NTRS1983

Photovoltaic module bypass diode encapsulation

The design and processing techniques necessary to incorporate bypass diodes within the module encapsulant are presented. The Semicon PN junction diode cells were selected. Diode junction to heat spreader thermal resistance measurements, performed on a variety of mounted diode chip types and sizes, have yielded values which are consistently below 1 deg C per watt, but show some instability when thermally cycled over the temperature range from -40 to 150 deg C. Three representative experimental modules, each incorporating integral bypass diode/heat spreader assemblies of various sizes, were designed. Thermal testing of these modules enabled the formulation of a recommended heat spreader plate sizing relationship. The production cost of three encapsulated bypass diode/heat spreader assemblies were compared with similarly rated externally mounted packaged diodes. It is concluded that, when proper designed and installed, these bypass diode devices will improve the overall reliability of a terrestrial array over a 20 year design lifetime.

Shepard, N. J., Jr.↗
DOE OSTI2020

Materials Data on Bi3Ru3O11 by Materials Project

Bi3Ru3O11 crystallizes in the cubic Pn-3 space group. The structure is three-dimensional. Ru+4.33+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing RuO6 octahedra. The corner-sharing octahedral tilt angles are 49°. There are a spread of Ru–O bond distances ranging from 1.98–2.02 Å. There are two inequivalent Bi3+ sites. In the first Bi3+ site, Bi3+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are two shorter (2.39 Å) and six longer (2.49 Å) Bi–O bond lengths. In the second Bi3+ site, Bi3+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Bi–O bond distances ranging from 2.26–2.81 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to four Bi3+ atoms to form a mixture of corner and edge-sharing OBi4 tetrahedra. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ru+4.33+ and two Bi3+ atoms. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ru+4.33+ and two equivalent Bi3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Bi3Pt3O11 by Materials Project

Pt3Bi3O11 crystallizes in the cubic Pn-3 space group. The structure is three-dimensional. Pt+4.33+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing PtO6 octahedra. The corner-sharing octahedral tilt angles are 55°. There are a spread of Pt–O bond distances ranging from 2.02–2.04 Å. There are two inequivalent Bi3+ sites. In the first Bi3+ site, Bi3+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Bi–O bond distances ranging from 2.28–2.77 Å. In the second Bi3+ site, Bi3+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are two shorter (2.43 Å) and six longer (2.48 Å) Bi–O bond lengths. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to four Bi3+ atoms to form a mixture of edge and corner-sharing OBi4 tetrahedra. In the second O2- site, O2- is bonded in a distorted L-shaped geometry to two equivalent Pt+4.33+ and two equivalent Bi3+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Pt+4.33+ and two Bi3+ atoms.

36 MATERIALS SCIENCE↗