Methods of repairing a substrate

NASA Technical Reports Server (NTRS)

Riedell, James A. (Inventor); Easler, Timothy E. (Inventor)

2011-01-01

A precursor of a ceramic adhesive suitable for use in a vacuum, thermal, and microgravity environment. The precursor of the ceramic adhesive includes a silicon-based, preceramic polymer and at least one ceramic powder selected from the group consisting of aluminum oxide, aluminum nitride, boron carbide, boron oxide, boron nitride, hafnium boride, hafnium carbide, hafnium oxide, lithium aluminate, molybdenum silicide, niobium carbide, niobium nitride, silicon boride, silicon carbide, silicon oxide, silicon nitride, tin oxide, tantalum boride, tantalum carbide, tantalum oxide, tantalum nitride, titanium boride, titanium carbide, titanium oxide, titanium nitride, yttrium oxide, zirconium boride, zirconium carbide, zirconium oxide, and zirconium silicate. Methods of forming the ceramic adhesive and of repairing a substrate in a vacuum and microgravity environment are also disclosed, as is a substrate repaired with the ceramic adhesive.

Characterization and diffusion model for the titanium boride layers formed on the Ti6Al4V alloy by plasma paste boriding

NASA Astrophysics Data System (ADS)

Keddam, Mourad; Taktak, Sukru

2017-03-01

The present study is focused on the estimation of activation energy of boron in the plasma paste borided Ti6Al4V alloy, which is extensively used in technological applications, using an analytical diffusion model. Titanium boride layers were successfully produced by plasma paste boriding method on the Ti6Al4V alloy in the temperature range of 973-1073 K for a treatment time ranging from 3 to 7 h. The presence of both TiB2 top-layer and TiB whiskers sub-layer was confirmed by the XRD analysis and SEM observations. The surface hardness of the borided alloy was evaluated using Micro-Knoop indenter. The formation rates of the TiB2 and TiB layers were found to have a parabolic character at all applied process temperatures. A diffusion model was suggested to estimate the boron diffusivities in TiB2 and TiB layers under certain assumptions, by considering the effect of boride incubation times. Basing on own experimental data on boriding kinetics, the activation energies of boron in TiB2 and TiB phases were estimated as 136.24 ± 0.5 and 63.76 ± 0.5 kJ mol-1, respectively. Finally, the obtained values of boron activation energies for Ti6Al4V alloy were compared with the data available in the literature.

Properties of boride-added powder metallurgy magnesium alloys

NASA Astrophysics Data System (ADS)

Tanaka, Atsushi; Yoshimura, Syota; Fujima, Takuya; Takagi, Ken-ichi

2009-06-01

Magnesium alloys with metallic borides, magnesium diboride (MgB2) or aluminum diboride (AlB2), were investigated regarding their mechanical properties, transverse rupture strength (TRS) and micro Vickers hardness (HV). The alloys were made from pure Mg, Al and B powders by mechanical alloying and hot pressing to have boride content of between 2.0 and 20 vol%. The alloy with AlB2 exhibited an obvious improvement of HV around a boride content of 6 vol% though the other alloy, with MgB2, did not. TRS showed moderate maxima around the same boride content region for the both alloys. X-ray diffraction measurements indicated an intermetallic compound, Mg17Al12, formed in the alloy with AlB2, which was consistent with its higher hardness.

Influence of laser alloying with boron and niobium on microstructure and properties of Nimonic 80A-alloy

NASA Astrophysics Data System (ADS)

Makuch, N.; Piasecki, A.; Dziarski, P.; Kulka, M.

2015-12-01

Ni-base superalloys were widely used in aeronautics, chemical and petrochemical industries due to their high corrosion resistance, high creep and rupture strength at high temperature. However, these alloys were not considered for applications in which conditions of appreciable mechanical wear were predominant. The diffusion boriding provided suitable protection against wear. Unfortunately, this process required long duration and high temperature. In this study, instead of the diffusion process, the laser alloying with boron and niobium was used in order to produce the hard and wear resistant layer on Nimonic 80A-alloy. The laser-alloying was carried out as a two-step process. First, the external cylindrical surface of specimens was pre-placed with a paste containing boron and niobium. Then, the pre-placed coating and the thin surface layer of the substrate were re-melted by a laser beam. The high laser beam power (P=1.56 kW) and high averaging irradiance (E=49.66 kW/cm2) provided the thick laser re-melted zone. The laser-borided layers were significantly thicker (470 μm) in comparison with the layers obtained as a consequence of the diffusion boriding. Simultaneously, the high overlapping of multiple laser tracks (86%) caused that the laser-alloyed layer was uniform in respect of the thickness. The produced layer consisted of nickel borides (Ni3B, Ni2B, Ni4B3, NiB), chromium borides (CrB, Cr2B), niobium borides (NbB2, NbB) and Ni-phase. The presence of hard borides caused the increase in microhardness up to 1000 HV in the re-melted zone. However, the measured values were lower than those-characteristic of niobium borides, chromium borides and nickel borides. The presence of the soft Ni-phase in re-melted zone was the reason for such a situation. After laser alloying, the significant increase in abrasive wear resistance was also observed. The mass wear intensity factor, as well as the relative mass loss of the laser-alloyed specimens, was over 10 times smaller in comparison with untreated Nimonic 80A-alloy.

In Situ Solid-Gas Reactivity of Nanoscaled Metal Borides from Molten Salt Synthesis.

PubMed

Gouget, Guillaume; Debecker, Damien P; Kim, Ara; Olivieri, Giorgia; Gallet, Jean-Jacques; Bournel, Fabrice; Thomas, Cyril; Ersen, Ovidiu; Moldovan, Simona; Sanchez, Clément; Carenco, Sophie; Portehault, David

2017-08-07

Metal borides have mostly been studied as bulk materials. The nanoscale provides new opportunities to investigate the properties of these materials, e.g., nanoscale hardening and surface reactivity. Metal borides are often considered stable solids because of their covalent character, but little is known on their behavior under a reactive atmosphere, especially reductive gases. We use molten salt synthesis at 750 °C to provide cobalt monoboride (CoB) nanocrystals embedded in an amorphous layer of cobalt(II) and partially oxidized boron as a model platform to study morphological, chemical, and structural evolutions of the boride and the superficial layer exposed to argon, dihydrogen (H 2 ), and a mixture of H 2 and carbon dioxide (CO 2 ) through a multiscale in situ approach: environmental transmission electron microscopy, synchrotron-based near-ambient-pressure X-ray photoelectron spectroscopy, and near-edge X-ray absorption spectroscopy. Although the material is stable under argon, H 2 triggers at 400 °C decomposition of CoB, leading to cobalt(0) nanoparticles. We then show that H 2 activates CoB for the catalysis of CO 2 methanation. A similar decomposition process is also observed on NiB nanocrystals under oxidizing conditions at 300 °C. Our work highlights the instability under reactive atmospheres of nanocrystalline cobalt and nickel borides obtained from molten salt synthesis. Therefore, we question the general stability of metal borides with distinct compositions under such conditions. These results shed light on the actual species in metal boride catalysis and provide the framework for future applications of metal borides in their stability domains.

Interlayer utilization (including metal borides) for subsequent deposition of NSD films via microwave plasma CVD on 316 and 440C stainless steels

NASA Astrophysics Data System (ADS)

Ballinger, Jared

Diamond thin films have promising applications in numerous fields due to the extreme properties of diamonds in conjunction with the surface enhancement of thin films. Biomedical applications are numerous including temporary implants and various dental and surgical instruments. The unique combination of properties offered by nanostructured diamond films that make it such an attractive surface coating include extreme hardness, low obtainable surface roughness, excellent thermal conductivity, and chemical inertness. Regrettably, numerous problems exist when attempting to coat stainless steel with diamond generating a readily delaminated film: outward diffusion of iron to the surface, inward diffusion of carbon limiting necessary surface carbon precursor, and the mismatch between the coefficients of thermal expansion yielding substantial residual stress. While some exotic methods have been attempted to overcome these hindrances, the most common approach is the use of an intermediate layer between the stainless steel substrate and the diamond thin film. In this research, both 316 stainless steel disks and 440C stainless steel ball bearings were tested with interlayers including discrete coatings and graded, diffusion-based surface enhancements. Titanium nitride and thermochemical diffusion boride interlayers were both examined for their effectiveness at allowing for the growth of continuous and adherent diamond films. Titanium nitride interlayers were deposited by cathodic arc vacuum deposition on 440C bearings. Lower temperature diamond processing resulted in improved surface coverage after cooling, but ultimately, both continuity and adhesion of the nanostructured diamond films were unacceptable. The ability to grow quality diamond films on TiN interlayers is in agreement with previous work on iron and low alloy steel substrates, and the similarly seen inadequate adhesion strength is partially a consequence of the lacking establishment of an interfacial carbide phase. Surface boriding was implemented using the novel method of microwave plasma CVD with a mixture of hydrogen and diborane gases. On 440C bearings, dual phase boride layers of Fe2B and FeB were formed which supported adhered nanostructured diamond films. Continuity of the films was not seamless with limited regions remaining uncoated potentially corresponding to delamination of the film as evidenced by the presence of tubular structures presumably composed of sp2 bonded carbon. Surface boriding of 316 stainless steel discs was conducted at various powers and pressures to achieve temperatures ranging from 550-800 °C. The substrate boriding temperature was found to substantially influence the resultant interlayer by altering the metal boride(s) present. The lowest temperatures produced an interlayer where CrB was the single detected phase, higher temperatures yielded the presence of only Fe2B, and a combination of the two phases resulted from an intermediate boriding temperature. Compared with the more common, commercialized boriding methods, this a profound result given the problems posed by the FeB phase in addition to other advantages offered by CVD processes and microwave generated plasmas in general. Indentation testing of the boride layers revealed excellent adhesion strength for all borided interlayers, and above all, no evidence of cracking was observed for a sole Fe2B phase. As with boriding of 440C bearings, subsequent diamond deposition was achieved on these interlayers with substantially improved adhesion strength relative to diamond coated TiN interlayers. Both XRD and Raman spectroscopy confirmed a nanostructured diamond film with interfacial chromium carbides responsible for enhanced adhesion strength. Interlayers consisting solely of Fe2B have displayed an ability to support fully continuous nanostructured diamond films, yet additional study is required for consistent reproduction. This is in good agreement with initial work on pack borided high alloy steels to promote diamond film surface modification. The future direction for continued research of nanostructured diamond coatings on microwave plasma CVD borided stainless steel should further investigate the adhesion of both borided interlayers and subsequent NSD films in addition to short, interrupted diamond depositions to study the interlayer/diamond film interface.

Plasma boriding of a cobalt-chromium alloy as an interlayer for nanostructured diamond growth

NASA Astrophysics Data System (ADS)

Johnston, Jamin M.; Jubinsky, Matthew; Catledge, Shane A.

2015-02-01

Chemical vapor deposited (CVD) diamond coatings can potentially improve the wear resistance of cobalt-chromium medical implant surfaces, but the high cobalt content in these alloys acts as a catalyst to form graphitic carbon. Boriding by high temperature liquid baths and powder packing has been shown to improve CVD diamond compatibility with cobalt alloys. We use the microwave plasma-enhanced (PE) CVD process to deposit interlayers composed primarily of the borides of cobalt and chromium. The use of diborane (B2H6) in the plasma feedgas allows for the formation of a robust boride interlayer for suppressing graphitic carbon during subsequent CVD of nano-structured diamond (NSD). This metal-boride interlayer is shown to be an effective diffusion barrier against elemental cobalt for improving nucleation and adhesion of NSD coatings on a CoCrMo alloy. Migration of elemental cobalt to the surface of the interlayer is significantly reduced and undetectable on the surface of the subsequently-grown NSD coating. The effects of PECVD boriding are compared for a range of substrate temperatures and deposition times and are evaluated using glancing-angle X-ray diffraction (XRD), cross-sectional scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and micro-Raman spectroscopy. Boriding of CoCrMo results in adhered nanostructured diamond coatings with low surface roughness.

Analysis of Deformation Substructures in a Notched LCF Sample Under Dwell Condition in a Ni-Based Superalloy (PREPRINT)

DTIC Science & Technology

2012-08-01

interior, and carbides and borides at the grain boundaries. Blocky carbide particles can also be seen in the grain interior (Figure 1b). The borides ...can be seen distributed (b) higher magnification image of a typical grain boundary decorated with carbide and boride particles. Bi-modal distribution

Future Directions for Selected Topics in Physics and Materials Science

DTIC Science & Technology

2012-07-12

referred to as lightides (e.g. borides , nitrides, phosphides) • Materials for energy conversion, energy storage, energy transport and energy production...Distributed nanosystems and sensors • Strategy for multilayered combinatorics • lightides ( borides , nitrides, phosphides, • New applications for...Strategy for multilayered combinatorics Lightides ( borides , nitrides, phosphides) • Energy conversion, .storage and production • Precision control

Plasma metallurgical production of nanocrystalline borides and carbides

NASA Astrophysics Data System (ADS)

Galevsky, G. V.; Rudneva, V. V.; Cherepanov, A. N.; Galevsky, S. G.; Efimova, K. A.

2016-09-01

he experience in production and study of properties of nanocrystalline borides and chromium carbides, titanium, silicon was summarized. The design and features of the vertical three-jet once-through reactor with power 150 kW, used in the plasma metallurgical production, was described. The technological, thermotechnical and resource characteristics of the reactor were identified. The parameters of borides and carbides synthesis, their main characteristics in the nanodispersed state and equipment-technological scheme of production were provided. Evaluation of engineering-and-economical performance of the laboratory and industrial levels of borides and carbides production and the state corresponding to the segment of the world market was carried out.

The Growth Behavior of Titanium Boride Layers in α and β Phase Fields of Titanium

NASA Astrophysics Data System (ADS)

Lv, Xiaojun; Hu, Lingyun; Shuang, Yajing; Liu, Jianhua; Lai, Yanqing; Jiang, Liangxing; Li, Jie

2016-07-01

In this study, the commercially pure titanium was successfully electrochemical borided in a borax-based electrolyte. The process was carried out at a constant cathodic current density of 300 mA cm-2 and at temperatures of 1123 K and 1223 K (850 °C and 950 °C) for 0.5, 1, 2, 3, and 5 hours. The growth behavior of titanium boride layers in the α phase field of titanium was compared with that in the β phase field. After boriding, the presence of both the TiB2 top layer and TiB whisker sub-layer was confirmed by the X-ray diffraction (XRD) and scanning electron microscope. The relationship between the thickness of boride layers and boriding time was found to have a parabolic character in both α and β phase fields of titanium. The TiB whiskers showed ultra-fast growth rate in the β phase field. Its growth rate constant was found to be as high as 3.2002 × 10-13 m2 s-1. Besides, the chemical resistance of the TiB2 layer on the surface of titanium substrate was characterized by immersion tests in molten aluminum.

Kinetic Investigation and Wear Properties of Fe2B Layers on AISI 12L14 Steel

NASA Astrophysics Data System (ADS)

Keddam, M.; Ortiz-Dominguez, M.; Elias-Espinosa, M.; Arenas-Flores, A.; Zuno-Silva, J.; Zamarripa-Zepeda, D.; Gomez-Vargas, O. A.

2018-03-01

In the current study, the powder-pack boriding was applied to the AISI 12L14 steel in the temperature range 1123 K to 1273 K for an exposure time between 2 and 8 hours. The produced boride layer was composed of Fe2B with a sawtooth morphology. A diffusion model based on the integral method was applied to investigate the growth kinetics of Fe2B layers. As a main result, the boron diffusion coefficients in Fe2B were estimated by considering the principle of mass balance at the (Fe2B/substrate) interface with an inclusion of boride incubation times. The value of activation energy for boron diffusion in AISI 12L14 steel was estimated as 165 kJ mol-1 and compared with other values of activation energy found in the literature. An experimental validation of the present model was made by using four different boriding conditions. Furthermore, the Rockwell-C adhesion test was employed to assess the cohesion of boride layers to the base metal. The scratch and pin-on-disc tests were also carried out to analyze the effect of boriding on wear behavior of AISI 12L14 steel.

Suppression of Boride Formation in Transient Liquid Phase Bonding of Pairings of Parent Superalloy Materials with Different Compositions and Grain Structures and Resulting Mechanical Properties

NASA Astrophysics Data System (ADS)

Steuer, Susanne; Singer, Robert F.

2014-07-01

Two Ni-based superalloys, columnar grained Alloy 247 and single-crystal PWA1483, are joined by transient liquid phase bonding using an amorphous brazing foil containing boron as a melting point depressant. At lower brazing temperatures, two different morphologies of borides develop in both base materials: plate-like and globular ones. Their ratio to each other is temperature dependent. With very high brazing temperatures, the deleterious boride formation in Alloy 247 can be totally avoided, probably because the three-phase-field moves to higher alloying element contents. For the superalloy PWA1483, the formation of borides cannot be completely avoided at high brazing temperatures as incipient melting occurs. During subsequent solidification of these areas, Chinese-script-like borides precipitate. The mechanical properties (tensile tests at room and elevated temperatures and short-term creep rupture tests at elevated temperatures) for brazed samples without boride precipitation are very promising. Tensile strengths and creep times to 1 pct strain are comparable, respectively, higher than the ones of the weaker parent material for all tested temperatures and creep conditions (from 90 to 100 pct rsp. 175 to 250 pct).

Microstructure Evolution and Composition Control during the Processing of Thin-gage Metallic Foil (Preprint)

DTIC Science & Technology

2012-02-01

the presence of somewhat randomly-distributed carbides and borides (white particles in BSE images), this grain size was comparable to that observed...pinned by carbide/ boride particles (imaging white in Figure 8c). The very fine gamma-prime precipitates likely produced during magnetron sputtering...sputtered material. First, the carbide/ boride particles were nucleated and hence located preferentially at the grain boundaries in the sputtered

Novel Routes to Tune Thermal Conductivities and Thermoelectric Properties of Materials

DTIC Science & Technology

2012-11-15

expand the possibilities of borides as functional compou nds. A series of indium-free novel TCO compounds with novel crystal structures, has...powerful methods for modification were demonstrated in the borides , silicides and oxides. Introduction: The goal of this project is to...the possibility to modify the crystal structures can expand the possibilities of borides as functional compounds. A series of indium-free novel TCO

Alloying-Element Loss during High-Temperature Processing of a Nickel-Base Superalloy (Preprint)

DTIC Science & Technology

2013-01-01

precipitates, and the fine white/gray particles are carbides and borides . ............................................. 23 Figure 2. Aluminum...comparable size, and submicron carbides and borides . A fifteen-minute heat treatment at the subsolvus temperature used in the present work (i.e...precipitates, and ~0.3 volume pct. of carbides and borides with an average diameter of ~0.3 m (Figure 1) [5, 6]. B. Procedures To establish the

Amorphous Iron Borides: Preparation, Structure and Magnetic Properties.

DTIC Science & Technology

1982-09-28

temperature. External magnetic field experiments were performed in a superconducting solenoid with both source and absor- ber at 4.2 K. The observed...D-Ai20 919 AMORPHOUS IRON BORIDES: PREPARATION STRUCTURE AND i/i MAGNETIC PROPERTIES(U) JOHNS HOPKINS UNIV LAUREL NO APPLIED PHYSICS LRB K MOORJRNI...NATIONAL BUREAU OF STANOANOS-93-A 10 AMORPHOUS IRON BORIDES: PREPARATION, STRUCTURE ~AND MAGNETIC PROPERTIES FINAL REPORT Kishin Moorjani September 1982 U

Effect of Heat Treatment on Borides Precipitation and Mechanical Properties of CoCrFeNiAl1.8Cu0.7B0.3Si0.1 High-Entropy Alloy Prepared by Arc-Melting and Laser-Cladding

NASA Astrophysics Data System (ADS)

Zhang, H.; Tang, H.; He, Y. Z.; Zhang, J. L.; Li, W. H.; Guo, S.

2017-11-01

Effects of heat treatment on borides precipitation and mechanical properties of arc-melted and laser-cladded CoCrNiFeAl1.8Cu0.7B0.3Si0.1 high-entropy alloys were comparatively studied. The arc-melted alloy contains lots of long strip borides distributed in the body-centered cubic phase, with a hardness about 643 HV0.5. Laser-cladding can effectively inhibit the boride precipitation and the laser-cladded alloy is mainly composed of a simple bcc solid solution, with a high hardness about 769 HV0.5, indicating the strengthening effect by interstitial boron atoms is greater than the strengthening by borides precipitation. Heat treatments between 800°C and 1200°C can simultaneously improve the hardness and fracture toughness of arc-melted alloys, owing to the boride spheroidization, dissolution, re-precipitation, and hence the increased boron solubility and nano-precipitation in the bcc solid solution. By contrast, the hardness of laser-cladded alloys reduce after heat treatments in the same temperature range, due to the decreased boron solubility in the matrix.

Observation of Dust Particle Gyromotion in a Magnetized Dusty Plasma

NASA Astrophysics Data System (ADS)

Compton, C. S.; Amatucci, W. E.; Gatling, G.; Tejero, E.

2008-11-01

In dusty plasma research, gyromotion of the dust has been difficult to observe experimentally. Previous experiments by Amatucci et al. have shown gyromotion of a single dust particle [1]. This early work was performed with alumina dust that had a size distribution and non-uniformly shaped particles. In the current experiment, evidence of spherical, monodispersed, dust particles exhibiting gyromotion has been observed. Silica particles 0.97 micrometers in diameter are suspended in a DC glow discharge argon plasma. The experiment is performed in the Naval Research Laboratory's DUsty PLasma EXperiment (DUPLEX Jr.). DUPLEX is a 61-cm tall by 46-cm diameter acrylic chamber allowing full 360 degree optical access for diagnostics. The neutral pressure for the experiment is 230 mTorr with a 275 V bias between the circular electrodes. The electrodes have a separation of 4 cm. A strong magnetic field is created by 2 pairs of neodymium iron boride magnets placed above and below the anode and cathode respectively. The resulting field is 1.4 kG. The dust particles are illuminated with a 25 mW, 672 nm laser. Images are captured using an intensified CCD camera and a consumer digital video cassette recorder. Recent evidence of gyromotion of spherical, monodispersed, dust particles will be presented. [1] Amatucci, W.E., et al., Phys. Plasmas, 11, 2097 (2004)

Certain physical properties of cobalt and nickel borides

NASA Technical Reports Server (NTRS)

Kostetskiy, I. I.; Lvov, S. N.

1981-01-01

The temperature dependence of the electrical resistivity, the thermal conductivity, and the thermal emf of cobalt and nickel borides were studied. In the case of the nickel borides the magnetic susceptibility and the Hall coefficient were determined at room temperature. The results are discussed with allowance for the current carrier concentration, the effect of various mechanisms of current-carrier scattering and the location of the Fermi level in relation to the 3d band.

A study on the formation of solid state nanoscale materials using polyhedral borane compounds

NASA Astrophysics Data System (ADS)

Romero, Jennifer V.

The formation of boron containing materials using a variety of methods was explored. The pyrolysis of a metal boride precursor solution can be accomplished using a one-source method by combining TiCl4, B10H 14 and CH3CN in one reaction vessel and pyrolyzing it at temperatures above 900 °C. Amorphous dark blue colored films were obtained after the pyrolysis reactions. Well-defined spherical shaped grains or particles were observed by SEM. The amorphous films generated contained titanium, however, the determination of the boron content of the films was inconclusive. This one pot method making metal boride thin films has the advantage of being able to dictate the stoichiometry of the reactants. Another part of this work represents the first report of both the use of metal boride materials and the use of a titanium-based compound for the formation of nanotubes. This method provides a facile method for generating well-formed boron-containing carbon nanotubes in a "one-pot" process through an efficient aerosol process. The formation of metal boride corrosion resistant layers was also explored. It was shown that metallic substrates can be effectively boronized using paste mixtures containing boron carbide and borax. The formation of a Fe4B 2 iron boride phase was achieved, however, this iron boride phase does not give enough corrosion protection. The formation of a corrosion resistant metal boride coating with strong adhesion was accomplished by boronization of a thermal sprayed nickel layer on the surface of steel. Surfactants were explored as possible nanoreactors in which metal boride nanoparticles could be formed to use as nanotube growth catalyst via room temperature reaction. Different surfactants were used, but none of them successfully generated very well dispersed metal boride nanoparticles. Nanoparticles with varying shapes and sizes were generated which were highly amorphous. The carboxylic acid derivative of closo-C2B 10 cages was explored as a ligand in the hydrothermal preparation of coordination polymers with zinc salts. It was found that the stability of the cage is apparently insufficient under these conditions and cage degradation was observed. Consequently, a preliminary investigation of the preparation of dipyridyl derivatives of both the closo-C2B 10 and the closo-B12 cages was performed.

Synthesis and Characterization of YB4 Ceramics

DTIC Science & Technology

2011-06-24

capa bility at temperatures above 2000°C1 with adequate mechani cal properties and oxidation resistance. Refractory metal borides based on HfB2 and ZrB2...increase in the oxidation resistance was accomplished by the addition of the Group IV VI transition metal borides , which was the result of phase...metal borides for use as materials for ultra high temper ature (UHT) applications. However, for instance, yttrium tet raboride, YB4, appears promising as

Finding the Stable Structures of WxN1-x with an ab-initio High-Throughput Approach

DTIC Science & Technology

2014-03-13

cubic boron nitride[4], carbonitrides,[5] and transition metal borides .[6, 7] Over the past several years there has been considerable theoretical...include ionic and covalent structures which seem chemically similar to W-N. These include borides , carbides, oxides, and other nitrides. In this paper we...metallic alloys, [23–27] we extended it to include over fifty new structures. These include nitrides, oxides, borides , and carbides. The important

Magnesium Aluminum Borides as Explosive Materials

DTIC Science & Technology

2011-12-20

Metal Silicides , and Metal Borides by Chemical Vapour Deposition Using Single Organometallic Precursors,” Trans. Inst. Met. Finishing, 72, 127-129...391 (2003). 62. X. Xiaojing, D. Bohua, Q. Zuanhui, and L. Yuanhui, “ Preparation and Synthesis Mechanism of Li-B Alloy,” Rare Metal Materials and...SUPPLEMENTARY NOTES 14. ABSTRACT Metal boride.; and boroo carbide Witted l’"irh Al ’I\\· ere compared co B. Mg. Al Mg:-AJ and Si a.s poteotia! fuel ad.diti

Development of high temperature stable Ohmic and Schottky contacts on n-gallium nitride

NASA Astrophysics Data System (ADS)

Khanna, Rohit

In this work the effort was made to towards develop and investigate high temperature stable Ohmic and Schottky contacts for n type GaN. Various borides and refractory materials were incorporated in metallization scheme to best attain the desired effect of minimal degradation of contacts when placed at high temperatures. This work focuses on achieving a contact scheme using different borides which include two Tungsten Borides (namely W2B, W2B 5), Titanium Boride (TiB2), Chromium Boride (CrB2) and Zirconium Boride (ZrB2). Further a high temperature metal namely Iridium (Ir) was evaluated as a potential contact to n-GaN, as part of continuing improved device technology development. The main goal of this project was to investigate the most promising boride-based contact metallurgies on GaN, and finally to fabricate a High Electron Mobility Transistor (HEMT) and compare its reliability to a HEMT using present technology contact. Ohmic contacts were fabricated on n GaN using borides in the metallization scheme of Ti/Al/boride/Ti/Au. The characterization of the contacts was done using current-voltage measurements, scanning electron microscopy (SEM) and Auger Electron Spectroscopy (AES) measurements. The contacts formed gave specific contact resistance of the order of 10-5 to 10-6 Ohm-cm2. A minimum contact resistance of 1.5x10-6 O.cm 2 was achieved for the TiB2 based scheme at an annealing temperature of 850-900°C, which was comparable to a regular ohmic contact of Ti/Al/Ni/Au on n GaN. When some of borides contacts were placed on a hot plate or in hot oven for temperature ranging from 200°C to 350°C, the regular metallization contacts degraded before than borides ones. Even with a certain amount of intermixing of the metallization scheme the boride contacts showed minimal roughening and smoother morphology, which, in terms of edge acuity, is crucial for very small gate devices. Schottky contacts were also fabricated and characterized using all the five boride compounds. The barrier height obtained on n GaN was ˜0-5-0.6 eV which was low compared to those obtained by Pt or Ni. This barrier height is too low for use as a gate contact and they can only have limited use, perhaps, in gas sensors where large leakage current can be tolerated in exchange for better thermal reliability. AlGaN/GaN High Electron Mobility Transistors (HEMTs) were fabricated with Ti/Al/TiB2/Ti/Au source/drain ohmic contacts and a variety of gate metal schemes (Pt/Au, Ni/Au, Pt/TiB2/Au or Ni/TiB 2/Au) and were subjected to long-term annealing at 350°C. By comparison with companion devices with conventional Ti/Al/Pt/Au ohmic contacts and Pt/Au gate contacts, the HEMTs with boride-based ohmic metal and either Pt/Au, Ni/Au or Ni/TiB2/Au gate metal showed superior stability of both source-drain current and transconductance after 25 days aging at 350°C. The need for sputter deposition of the borides causes' problem in achieving significantly lower specific contact resistance than with conventional schemes deposited using e-beam evaporation. The borides also seem to be, in general, good getters for oxygen leading to sheet resistivity issues. Ir/Au Schottky contacts and Ti/Al/Ir/Au ohmic contacts on n-type GaN were investigated as a function of annealing temperature and compared to their more common Ni-based counterparts. The Ir/Au ohmic contacts on n-type GaN with n˜1017 cm-3 exhibited barrier heights of 0.55 eV after annealing at 700°C and displayed less intermixing of the contact metals compared to Ni/Au. A minimum specific contact resistance of 1.6 x 10-6 O.cm2 was obtained for the ohmic contacts on n-type GaN with n˜1018 cm-3 after annealing at 900°C. The measurement temperature dependence of contact resistance was similar for both Ti/Al/Ir/Au and Ti/Al/Ni/Au, suggesting the same transport mechanism was present in both types of contacts. The Ir-based ohmic contacts displayed superior thermal aging characteristics at 350°C. Auger Electron Spectroscopy showed that Ir is a superior diffusion barrier at these moderate temperatures than Ni.

Fabrication and Characterization of Plasma Electrolytic Borocarburized Layers on Q235 Low-Carbon Steel at Different Discharge Voltages

NASA Astrophysics Data System (ADS)

Wang, Bin; Wu, Jie; Jin, Xiaoyue; Wu, Xiaoling; Wu, Zhenglong; Xue, Wenbin

The influence of applied voltage on the plasma electrolytic borocarburizing (PEB/C) layer of Q235 low-carbon steel in high-concentration borax solution was investigated. XRD and XPS spectra of PEB/C layer confirmed that the modified boride layer mainly consisted of Fe2B phase, and the FeB phase only exists in the loose top layer. The applied voltage on Q235 steel played a key role in determining the properties of hardened layers. The thickness and microhardness of boride layers increased with the increase of the applied voltage, which led to superior corrosion and wear resistances of Q235 low-carbon steel. The diffusion coefficient (D) of boride layer at 280, 300 and 330V increased with borocarburizing temperature and ranged from 0.062×10-12m2/s to 0.462×10-12m2/s. The activation energy (Q) of boride layer growth during PEB/C treatment was only 52.83kJṡmol-1, which was much lower than that of the conventional boriding process.

Niobium boride layers deposition on the surface AISI D2 steel by a duplex treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kon, O., E-mail: okon42@htotmail.com; Pazarlioglu, S.; Sen, S.

2015-03-30

In this paper, we investigated the possibility of deposition of niobium boride layers on the surface of AISI D2 steel by a duplex treatment. At the first step of duplex treatment, boronizing was performed on AISI D2 steel samples at 1000{sup o}C for 2h and then pre-boronized samples niobized at 850°C, 900°C and 950°C using thermo-reactive deposition method for 1–4 h. The presence of the niobium boride layers such as NbB, NbB{sub 2} and Nb{sub 3}B{sub 4} and also iron boride phases such as FeB, Fe{sub 2}B were examined by X-ray diffraction analysis. Scanning electron microscope (SEM) and micro-hardness measurementsmore » were realized. Experimental studies showed that the depth of the coating layers increased with increasing temperature and times and also ranged from 0.42 µm to 2.43 µm, depending on treatment time and temperature. The hardness of the niobium boride layer was 2620±180 HV{sub 0.005}.« less

Crystal structure and phase stability of tungsten borides

NASA Astrophysics Data System (ADS)

Li, Quan; Zhou, Dan; Ma, Yanming; Chen, Changfeng

2013-03-01

We address the longstanding and controversial issue of ground-state structures of technically important tungsten borides using a first-principles structural search method via a particle-swarm optimization (PSO) algorithm. We have explored a large set of stable chemical compositions (convex hull) and clarified the ground-state structures for a wide range of boron concentrations, including W2B, W3B2,WB,W2B3, WB2,W2B5, WB3, and WB4. We further assessed relative stability of various tungsten borides and compared the calculated results with previously reported experimental data. The phase diagram predicted by the presented calculations may serve as a useful guide for synthesis of a variety of tungsten borides. This work was supported by DOE Grant No. DE-FC52-06NA26274.

High Energy Advanced Thermal Storage for Spacecraft Solar Thermal Power and Propulsion Systems

DTIC Science & Technology

2011-10-12

Vol. 108, No. 6, June 1961, pp. 568-572. 38. Storms, E. and Mueller, B., "Phase Relations and Thermodynamic Properties of Transition Metal Borides ...T., and Naka, S., "Formation Process of Tungsten Borides by Solid State Reaction Between Tungsten and Amorphous Boron," Journal of Materials...Molybdenum- Borides ," Journal of Metals, September 1952, pp. 983-988. 41. Ellis, R.C., “Various Preparations of Elemental Boron,” Proceedings of the 1st

Finding the Stable Structures of N1-xWx with an Ab Initio High-Throughput Approach

DTIC Science & Technology

2015-05-26

W. These include borides , carbides, oxides, and other nitrides. We also invented many structures to mimic the random pattern of vacancies on both the...structures. These include nitrides, oxides, borides , and carbides, as well as supercells of standard structures with atoms removed to mimic the random patter...1930). [15] R. Kiessling and Y. H. Liu, Thermal stability of the chromium, iron, and tungsten borides in streaming ammonia and the existence of a new

Molten Boron Phase-Change Thermal Energy Storage to Augment Solar Thermal Propulsion Systems

DTIC Science & Technology

2011-07-13

Thermodynamic Properties of Transition Metal Borides . I. The Molybdenum-boron system and Elemental Boron," Journal of Physical Chemistry, Vol. 81...February 1977, pp. 318-324. 38Itoh, H., Matsudaira, T., and Naka, S., "Formation Process of Tungsten Borides by Solid State Reaction Between Tungsten...Molybdenum-Boron and Some Properties of The Molybdenum- Borides ," Journal of Metals, September 1952, pp. 983-988. 40Stout, N. D., Mar, R. W., and Boo, W. O

Effects of Tungsten Addition on the Microstructure and Corrosion Resistance of Fe-3.5B Alloy in Liquid Zinc

PubMed Central

Liu, Xin; Wang, Mengmeng; Yin, Fucheng; Ouyang, Xuemei; Li, Zhi

2017-01-01

The effects of tungsten addition on the microstructure and corrosion resistance of Fe-3.5B alloys in a liquid zinc bath at 520 °C were investigated by means of scanning electron microscopy, X-ray diffraction and electron probe micro-analysis. The microstructure evolution in different alloys is analyzed and discussed using an extrapolated Fe-B-W ternary phase diagram. Experimental results show that there are three kinds of borides, the reticular (Fe, W)2B, the rod-like (Fe, W)3B and flower-like FeWB. The addition of tungsten can refine the microstructure and improve the stability of the reticular borides. Besides, it is beneficial to the formation of the metastable (Fe, W)3B phase. The resultant Fe-3.5B-11W (wt %) alloy possesses excellent corrosion resistance to liquid zinc. When tungsten content exceeds 11 wt %, the formed flower-like FeWB phase destroys the integrity of the reticular borides and results in the deterioration of the corrosion resistance. Also, the corrosion failure resulting from the spalling of borides due to the initiation of micro-cracks in the grain boundary of borides is discussed in this paper. PMID:28772759

Non-Contact Tabletop Mechanical Testing of Ultra-High Temperature Ceramics

DTIC Science & Technology

2012-05-01

class of refractory materials including transition metal borides , carbides and nitrides e.g. ZrB2l HfB2) ZrC, HfC, TaC, HfN and ZrN. They recently...ike oxidizing atmospheres, at very high temperatures Refractory borides like ZrB2 and HfB2 have extremely high melting temperatures (over 3000°C...But borides are very poor in oxidation resistance, due to the nature of thär oxides Non-protective ZrCfe or Hf02 and volatile liquid B203. Addition

Dislocation Decorrelation and Relationship to Deformation Microtwins during Creep of a Gamma’ Precipitate Strengthened Ni-based Superalloy

DTIC Science & Technology

2011-11-01

Deformation is highly localized around stress concentrators such as carbides, borides and serrated grain boundaries, which act as sources of a/2h110i...highly localized around stress concentrators such as carbides, borides and serrated grain boundaries, which act as sources of a/2h110i matrix-type...phase at different thicknesses. 7328 R.R. Unocic et al. / Acta Materialia 59 (2011) 7325–7339 the image. A number of carbide and/or boride phases are

Beta cell device using icosahedral boride compounds

DOEpatents

Aselage, Terrence L.; Emin, David

2002-01-01

A beta cell for converting beta-particle energies into electrical energy having a semiconductor junction that incorporates an icosahedral boride compound selected from B.sub.12 As.sub.2, B.sub.12 P.sub.2, elemental boron having an .alpha.-rhombohedral structure, elemental boron having a .beta.-rhombohedral structure, and boron carbides of the chemical formula B.sub.12-x C.sub.3-x, where 0.15

Materials flow analysis of neodymium, status of rare earth metal in the Republic of Korea.

PubMed

Swain, Basudev; Kang, Leeseung; Mishra, Chinmayee; Ahn, JoongWoo; Hong, Hyun Seon

2015-11-01

Materials flow analysis of neodymium, status of rare earth elements (REEs) in the Republic of Korea has been investigated. Information from various resources like the Korean Ministry of Environment, Korea international trade association, United Nations Commodity Trade Statistics Database and from individual industry were collected and analyzed for materials flow analysis of neodymium. Demand of neodymium in the Republic of Korea for the year 2010 was 409.5 tons out of which the majority of neodymium, i.e., 68.41% was consumed by domestic electronics industry followed by medical appliances manufacturing (13.36%). The Republic Korea is one of the biggest consumer and leading exporter of these industrial products, absolutely depends on import of neodymium, as the country is lacking natural resources. The Republic of Korea has imported 325.9 tons of neodymium permanent magnet and 79.5 tons of neodymium containing equipment parts mainly for electronics, medical appliances, and heavy/light vehicles manufacturing industry. Out of which 95.4 tons of neodymium permanent magnet get exported as an intermediate product and 140.6 tons of neodymium in the form of consumable products get exported. Worldwide the neodymium is at the high end of supply chain critical metal because of increasing demand, scarcity and irreplaceable for technological application. To bring back the neodymium to supply stream the recycling of end of life neodymium-bearing waste can be a feasible option. Out of total domestic consumption, only 21.9 tons of neodymium have been collected and subsequently recycled. From material flow analysis, the requirement for an efficient recycling system and element-wise material flow management for these REEs in the Republic of Korea were realized and recommended. Copyright © 2015 Elsevier Ltd. All rights reserved.

Nano-Disperse Borides and Carbides: Plasma Technology Production, Specific Properties, Economic Evaluation

NASA Astrophysics Data System (ADS)

Galevskii, G. V.; Rudneva, V. V.; Galevskii, S. G.; Tomas, K. I.; Zubkov, M. S.

2016-04-01

The experience of production and study on properties of nano-disperse chromium and titanium borides and carbides, and silicon carbide has been generalized. The structure and special service aspects of utilized plasma-metallurgical complex equipped with a three-jet direct-flow reactor with a capacity of 150 kW have been outlined. Processing, heat engineering and service life characteristics of the reactor are specified. The synthesis parameters of borides and carbides, as well as their basic characteristics in nano-disperse condition and their production flow diagram are outlined. Engineering and economic performance of synthesizing borides in laboratory and industrial conditions is assessed, and the respective segment of the international market as well. The work is performed at State Siberian Industrial University as a project part of the State Order of Ministry of Science and Education of the Russian Federation No. 11.1531/2014/K.

The effect of boriding on wear resistance of cold work tool steel

NASA Astrophysics Data System (ADS)

Anzawa, Y.; Koyama, S.; Shohji, I.

2017-05-01

Recently, boriding has attracted extensive attention as surface stiffening processing of plain steel. In this research, the influence of processing time on the formation layer of cold work tool steel (KD11MAX) by Al added fused salt bath was examined. In addition, in order to improve the abrasion resistance of KD11MAX, the effect of the treatment of boronization on the formation layer has been investigated. Boriding were performed in molten borax which contained about 10 mass% Al at processing time of 1.8 ~ 7.2 ks (processing temperature of 1303 K). As a result of the examination, the hardness of the boriding layer becomes about 1900 HV when the processing time of 3.6 ks. Also the abrasion resistance has improved remarkably. Furthermore, it was revealed that the formation layer was boronized iron from the Vickers hardness and analysis of the X-ray diffraction measurement.

Metal Immiscibility Route to Synthesis of Ultrathin Carbides, Borides, and Nitrides.

PubMed

Wang, Zixing; Kochat, Vidya; Pandey, Prafull; Kashyap, Sanjay; Chattopadhyay, Soham; Samanta, Atanu; Sarkar, Suman; Manimunda, Praveena; Zhang, Xiang; Asif, Syed; Singh, Abhisek K; Chattopadhyay, Kamanio; Tiwary, Chandra Sekhar; Ajayan, Pulickel M

2017-08-01

Ultrathin ceramic coatings are of high interest as protective coatings from aviation to biomedical applications. Here, a generic approach of making scalable ultrathin transition metal-carbide/boride/nitride using immiscibility of two metals is demonstrated. Ultrathin tantalum carbide, nitride, and boride are grown using chemical vapor deposition by heating a tantalum-copper bilayer with corresponding precursor (C 2 H 2 , B powder, and NH 3 ). The ultrathin crystals are found on the copper surface (opposite of the metal-metal junction). A detailed microscopy analysis followed by density functional theory based calculation demonstrates the migration mechanism, where Ta atoms prefer to stay in clusters in the Cu matrix. These ultrathin materials have good interface attachment with Cu, improving the scratch resistance and oxidation resistance of Cu. This metal-metal immiscibility system can be extended to other metals to synthesize metal carbide, boride, and nitride coatings. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kinetics and Tribological Characterization of Pack-Borided AISI 1025 Steel

NASA Astrophysics Data System (ADS)

Gómez-Vargas, O. A.; Keddam, M.; Ortiz-Domínguez, M.

2017-03-01

In this present study, the AISI 1025 steel was pack-borided in the temperature range of 1,123-1,273 K for different treatment times ranging from 2 to 8 h. A diffusion model was suggested to estimate the boron diffusion coefficients in the Fe2B layers. As a result, the boron activation energy for the AISI 1025 steel was estimated as 174.36 kJ/mol. This value of energy was compared with the literature data. To extend the validity of the present model, other additional boriding conditions were considered. The boride layers formed on the AISI 1025 steel were characterized by the following experimental techniques: scanning electron microscopy, X-ray diffraction analysis and the Daimler-Benz Rockwell-C indentation technique. Finally, the scratch and pin-on-disc tests for wear resistance were achieved using an LG Motion Ltd and a CSM tribometer, respectively, under dry sliding conditions.

Ceramic material suitable for repair of a space vehicle component in a microgravity and vacuum environment, method of making same, and method of repairing a space vehicle component

NASA Technical Reports Server (NTRS)

Riedell, James A. (Inventor); Easler, Timothy E. (Inventor)

2009-01-01

A precursor of a ceramic adhesive suitable for use in a vacuum, thermal, and microgravity environment. The precursor of the ceramic adhesive includes a silicon-based, preceramic polymer and at least one ceramic powder selected from the group consisting of aluminum oxide, aluminum nitride, boron carbide, boron oxide, boron nitride, hafnium boride, hafnium carbide, hafnium oxide, lithium aluminate, molybdenum silicide, niobium carbide, niobium nitride, silicon boride, silicon carbide, silicon oxide, silicon nitride, tin oxide, tantalum boride, tantalum carbide, tantalum oxide, tantalum nitride, titanium boride, titanium carbide, titanium oxide, titanium nitride, yttrium oxide, zirconium diboride, zirconium carbide, zirconium oxide, and zirconium silicate. Methods of forming the ceramic adhesive and of repairing a substrate in a vacuum and microgravity environment are also disclosed, as is a substrate repaired with the ceramic adhesive.

Effect of borides on hot deformation behavior and microstructure evolution of powder metallurgy high borated stainless steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Xuan

To investigate borides effect on the hot deformation behavior and microstructure evolution of powder metallurgy high borated stainless steel, hot compression tests at the temperatures of 950– 1150 °C and the strain rates of 0.01– 10 s{sup −1} were performed. Flow stress curves indicated that borides increased the material's stress level at low temperature but the strength was sacrificed at temperatures above 1100 °C. A hyperbolic-sine equation was used to characterize the dependence of the flow stress on the deformation temperature and strain rate. The hot deformation activation energy and stress exponent were determined to be 355 kJ/mol and 3.2,more » respectively. The main factors leading to activation energy and stress exponent of studied steel lower than those of commercial 304 stainless steel were discussed. Processing maps at the strains of 0.1, 0.3, 0.5, and 0.7 showed that flow instability mainly concentrated at 950– 1150 °C and strain rate higher than 0.6 s{sup −1}. Results of microstructure illustrated that dynamic recrystallization was fully completed at both high temperature-low strain rate and low temperature-high strain rate. In the instability region cracks were generated in addition to cavities. Interestingly, borides maintained a preferential orientation resulting from particle rotation during compression. - Highlights: •The decrement of activation energy was affected by boride and boron solution. •The decrease of stress exponent was influenced by composition and Cottrell atmosphere. •Boride represented a preferential orientation caused by particle rotation.« less

On the Correlation between Morphology of alpha and Its Crystallographic Orientation Relationship with TiB and Beta in Boron Containing Ti-5Al-5Mo-5V-3Cr-0.5Fe Alloy (Preprint)

DTIC Science & Technology

2012-01-01

submitted to Metallurgical Transactions. This document contains color. 14. ABSTRACT While the role of borides on the microstructure of titanium...Ohio, U.S.A. Abstract While the role of borides on the microstructure of titanium alloys has been discussed in many previous reports, this paper...morphology of  precipitates nucleating from boride precipitates present in the  matrix of a titanium alloy; and (b) to investigate the role of presence or

Thermodynamic modelling of phase equilibrium in system Ti-B-Si-C, synthesis and phases composition of borides and carbides layers on titanic alloyVT-1 at electron beam treatment in vacuum

NASA Astrophysics Data System (ADS)

Smirnyagina, N. N.; Khaltanova, V. M.; Lapina, A. E.; Dasheev, D. E.

2017-01-01

Composite layers on the basis of carbides and borides the titan and silicon on titanic alloy VT-1 are generated at diffused saturation in vacuum. Formation in a composite of MAX phase Ti3SiC2 is shown. Thermodynamic research of phase equilibrium in systems Ti-Si-C and Ti-B-C in the conditions of high vacuum is executed. The thermodynamics, formation mechanisms of superfirm layers borides and carbides of the titan and silicon are investigated.

Effect of mechanical activation on jell boronizing treatment of the AISI 4140

NASA Astrophysics Data System (ADS)

Yılmaz, S. O.; Karataş, S.

2013-06-01

The article presents the effect of mechanical activation on the growth kinetics of boride layer of boronized AISI 4140 steel. The samples were boronized by ferroboron + (SiO2-Na2O) powders for 873-1173 K temperature and 2, 4, 6 and 8 h times, respectively. The morphology and types of borides formed on the surface of AISI 4140 steel substrate were analyzed. Layer growth kinetics were analyzed by measuring the extent of penetration of FeB and Fe2B sublayers as function of treatment time and temperature in the range of 873-1173 K. High diffusivity was obtained by creating a large number of defects through mechanical activation in the form of nanometer sized crystalline particles through the repeated fracturing and cold-welding of the powder particles, and a depth of 100 μm was found in the specimen borided by the 2 h MA powders, for 4 h and 1073 K, where 2000-2350 HV were measured. Consequently, the application conditions of boronizing were improved by usage of mechanical activation. The preferred Fe2B boride without FeB could be formed in the boride layer under 973 K boronizing temperature by mechanically activated by ferroboron + sodium silicate powder mixture due to the decrease of the activation energy.

Yttria Nanoparticle Reinforced Commercially Pure (CP) Titanium

DTIC Science & Technology

2011-09-01

nanoparticles as well as titanium boride (TiB) reinforcements were produced through gas atomization. After consolidation and extrusion, room temperature...pure FE iron O oxygen Ti titanium TiB titanium boride TYS tensile yield strength UTS ultimate tensile strength wt% weight percent Y2O3

Growth kinetics of borided layers: Artificial neural network and least square approaches

NASA Astrophysics Data System (ADS)

Campos, I.; Islas, M.; Ramírez, G.; VillaVelázquez, C.; Mota, C.

2007-05-01

The present study evaluates the growth kinetics of the boride layer Fe 2B in AISI 1045 steel, by means of neural networks and the least square techniques. The Fe 2B phase was formed at the material surface using the paste boriding process. The surface boron potential was modified considering different boron paste thicknesses, with exposure times of 2, 4 and 6 h, and treatment temperatures of 1193, 1223 and 1273 K. The neural network and the least square models were set by the layer thickness of Fe 2B phase, and assuming that the growth of the boride layer follows a parabolic law. The reliability of the techniques used is compared with a set of experiments at a temperature of 1223 K with 5 h of treatment time and boron potentials of 2, 3, 4 and 5 mm. The results of the Fe 2B layer thicknesses show a mean error of 5.31% for the neural network and 3.42% for the least square method.

Selection of peptides binding to metallic borides by screening M13 phage display libraries.

PubMed

Ploss, Martin; Facey, Sandra J; Bruhn, Carina; Zemel, Limor; Hofmann, Kathrin; Stark, Robert W; Albert, Barbara; Hauer, Bernhard

2014-02-10

Metal borides are a class of inorganic solids that is much less known and investigated than for example metal oxides or intermetallics. At the same time it is a highly versatile and interesting class of compounds in terms of physical and chemical properties, like semiconductivity, ferromagnetism, or catalytic activity. This makes these substances attractive for the generation of new materials. Very little is known about the interaction between organic materials and borides. To generate nanostructured and composite materials which consist of metal borides and organic modifiers it is necessary to develop new synthetic strategies. Phage peptide display libraries are commonly used to select peptides that bind specifically to metals, metal oxides, and semiconductors. Further, these binding peptides can serve as templates to control the nucleation and growth of inorganic nanoparticles. Additionally, the combination of two different binding motifs into a single bifunctional phage could be useful for the generation of new composite materials. In this study, we have identified a unique set of sequences that bind to amorphous and crystalline nickel boride (Ni3B) nanoparticles, from a random peptide library using the phage display technique. Using this technique, strong binders were identified that are selective for nickel boride. Sequence analysis of the peptides revealed that the sequences exhibit similar, yet subtle different patterns of amino acid usage. Although a predominant binding motif was not observed, certain charged amino acids emerged as essential in specific binding to both substrates. The 7-mer peptide sequence LGFREKE, isolated on amorphous Ni3B emerged as the best binder for both substrates. Fluorescence microscopy and atomic force microscopy confirmed the specific binding affinity of LGFREKE expressing phage to amorphous and crystalline Ni3B nanoparticles. This study is, to our knowledge, the first to identify peptides that bind specifically to amorphous and to crystalline Ni3B nanoparticles. We think that the identified strong binding sequences described here could potentially serve for the utilisation of M13 phage as a viable alternative to other methods to create tailor-made boride composite materials or new catalytic surfaces by a biologically driven nano-assembly synthesis and structuring.

Recycling potential of neodymium: the case of computer hard disk drives.

PubMed

Sprecher, Benjamin; Kleijn, Rene; Kramer, Gert Jan

2014-08-19

Neodymium, one of the more critically scarce rare earth metals, is often used in sustainable technologies. In this study, we investigate the potential contribution of neodymium recycling to reducing scarcity in supply, with a case study on computer hard disk drives (HDDs). We first review the literature on neodymium production and recycling potential. From this review, we find that recycling of computer HDDs is currently the most feasible pathway toward large-scale recycling of neodymium, even though HDDs do not represent the largest application of neodymium. We then use a combination of dynamic modeling and empirical experiments to conclude that within the application of NdFeB magnets for HDDs, the potential for loop-closing is significant: up to 57% in 2017. However, compared to the total NdFeB production capacity, the recovery potential from HDDs is relatively small (in the 1-3% range). The distributed nature of neodymium poses a significant challenge for recycling of neodymium.

Synthesis of Binary Transition Metal Nitrides, Carbides and Borides from the Elements in the Laser-Heated Diamond Anvil Cell and Their Structure-Property Relations

PubMed Central

Friedrich, Alexandra; Winkler, Björn; Juarez-Arellano, Erick A.; Bayarjargal, Lkhamsuren

2011-01-01

Transition metal nitrides, carbides and borides have a high potential for industrial applications as they not only have a high melting point but are generally harder and less compressible than the pure metals. Here we summarize recent advances in the synthesis of binary transition metal nitrides, carbides and borides focusing on the reaction of the elements at extreme conditions generated within the laser-heated diamond anvil cell. The current knowledge of their structures and high-pressure properties like high-(p,T) stability, compressibility and hardness is described as obtained from experiments. PMID:28824101

Directionally Solidified Eutectic Ceramics for Multifunctional Aerospace Applications

DTIC Science & Technology

2013-01-01

eutectic materials development through a new initiative entitled Boride Eutectic Project. These results first time organize and populate materials...property databases, and utilize an iterative feedback routine to constantly improve the design process of the boride eutectics LaB6-MeB2 (Me = Zr, Hf, Ti

Superabrasive boride and a method of preparing the same by mechanical alloying and hot pressing

DOEpatents

Cook, Bruce A.; Harringa, Joel L.; Russell, Alan M.

2002-08-13

A ceramic material which is an orthorhombic boride of the general formula: AlMgB.sub.14 :X, with X being a doping agent. The ceramic is a superabrasive, and in most instances provides a hardness of 40 GPa or greater.

Theoretical and Experimental Investigations on the Mechanism of Carbothermal Reduction of Zirconia (Preprint)

DTIC Science & Technology

2012-08-01

Properties. Abyss Books, Washington, D.C., 2002. 2. G. Montel, A. Lebugle and H. Pastor. "Manufacture of Materials Containing Refractory Borides ...and ZrO2," International Journal of Refractory Metals and Hard Materials, 17, 235-43 (1999). 10. A.W. Weimer, Carbide, nitride and boride

Adhesive and Cohesive Strength in FeB/Fe2B Systems

NASA Astrophysics Data System (ADS)

Meneses-Amador, A.; Blancas-Pérez, D.; Corpus-Mejía, R.; Rodríguez-Castro, G. A.; Martínez-Trinidad, J.; Jiménez-Tinoco, L. F.

2018-05-01

In this work, FeB/Fe2B systems were evaluated by the scratch test. The powder-pack boriding process was performed on the surface of AISI M2 steel. The mechanical parameters, such as yield stress and Young's modulus of the boride layer, were obtained by the instrumented indentation technique. Residual stresses produced on the boride layer were estimated by using the x-ray diffraction (XRD) technique. The scratch test was performed in order to evaluate the cohesive/adhesive strength of the FeB/Fe2B coating. In addition, a numerical evaluation of the scratch test on boride layers was performed by the finite element method. Maximum principal stresses were related to the failure mechanisms observed by the experimental scratch test. Shear stresses at the interfaces of the FeB/Fe2B/substrate system were also evaluated. Finally, the results obtained provide essential information about the effect of the layer thickness, the residual stresses, and the resilience modulus on the cohesive/adhesive strength in FeB/Fe2B systems.

The Effects of Borides on the Mechanical Properties of TLPB Repaired Inconel 738 Superalloy

NASA Astrophysics Data System (ADS)

Wei, J.; Ye, Y.; Sun, Z.; Zou, G.; Bai, H.; Wu, A.; Liu, L.

2017-10-01

The transient liquid phase diffusion bonding (TLPB) method was used to repair an artificial crack in Inconel 738, which was notched by a femtosecond laser. Mixed ratios of BNi-1a:DF-4B were investigated at the bonding temperature of 1373 K (1100 °C) for 2 to 36 hours. The effect of borides on the mechanical properties of TLPB repaired joints was studied through analysis of the microstructure, fracture path, and morphology observations. The borides formation, morphology, distribution, and joints strength were studied in detail. The results showed that the diffusion of B can either increase or decrease the joint strength, depending on its distribution and morphology. The amount of large blocky Ni-B compounds in the precipitate zone were reduced with increasing holding time, which resulted in an increase in joint strength. Nevertheless, further increasing the holding time led to a decrease in joint strength because of the formation of continuous acicular borides in the diffusion-affected zone. The fracture modes of TLPB joints were also discussed on the basis of the microstructure and fractography.

Micro-Abrasion Wear Resistance of Borided 316L Stainless Steel and AISI 1018 Steel

NASA Astrophysics Data System (ADS)

Reséndiz-Calderon, C. D.; Rodríguez-Castro, G. A.; Meneses-Amador, A.; Campos-Silva, I. E.; Andraca-Adame, J.; Palomar-Pardavé, M. E.; Gallardo-Hernández, E. A.

2017-11-01

The 316L stainless steel has high corrosion resistance but low tribological performance. In different industrial sectors (biomedical, chemical, petrochemical, and nuclear engineering), improvement upon wear resistance of 316L stainless steel components using accessible and inexpensive methods is critical. The AISI 1018 steel is widely used in industry, but its tribological performance is not the best among steels. Therefore, in this study the behavior of the borided 316L stainless steel and 1018 steel is evaluated under micro-abrasion wear. The boriding was carried out at 1223 K over 6 h of exposure time, resulting in a biphase layer composed of FeB/Fe2B phases. In order to evaluate Fe2B phase with no influence from FeB phase, AISI 1018 steel samples were borided at 1273 K for over 20 min and then diffusion annealed at 1273 K over 2 h to obtain a Fe2B mono-phase layer. Micro-abrasion wear resistance was evaluated by a commercial micro-abrasion testing rig using a mix of F-1200 SiC particles with deionized water as abrasive slurry. The obtained wear rates for FeB and Fe2B phases and for the 316L stainless steel were compared. Wear resistance of 316L stainless steel increases after boriding. The wear mechanisms for both phases and for the stainless steel were identified. Also, transient conditions for rolling and grooving abrasion were determined for the FeB and Fe2B phases.

Surface decoration through electrostatic interaction leading to enhanced reactivity: Low temperature synthesis of nanostructured chromium borides (CrB and CrB{sub 2})

DOE Office of Scientific and Technical Information (OSTI.GOV)

Menaka,; Kumar, Bharat; Kumar, Sandeep

The present study describes a novel low temperature route at ambient pressure for the synthesis of nanocrystalline chromium borides (CrB and CrB{sub 2}) without using any flux or additives. The favorable and intimate mixing of nanoparticles of chromium acetate (Cr source) and boron forms an active chromium–boron precursor which decomposes at much lower temperature (400 °C) to form CrB (which is ∼1000 °C less than the known ambient pressure synthesis). The chromium acetate nanoparticles (∼5 nm) decorate the larger boron particles (150–200 nm) due to electrostatic interactions resulting from opposing surface charges of boron (zeta potential:+48.101 mV) and chromium acetatemore » (zeta potential:−4.021 mV) in ethanolic medium and is evident in the TEM micrographs. The above method leads to the formation of pure CrB film like structure at 400 °C and nanospheres (40–60 nm) at 600 °C. Also, chromium diboride (CrB{sub 2}) nanoparticles (25 nm) could be obtained at 1000 °C. - Graphical abstract: Variation of surface charge of reactants, precursor and the products, chromium borides (CrB and CrB{sub 2}). Highlights: ► Novel borothermal reduction process for synthesis of chromium boride. ► Significant lowering of reaction temperature to obtain nanocrystalline chromium boride. ► Enhanced reactivity due to appropriate surface interactions.« less

Investigation of diffusional interaction between P91 grade ferritic steel and Fe-15 wt.%B alloy and study of kinetics of boride formation at high temperature

NASA Astrophysics Data System (ADS)

Rai, Arun Kumar; Vijayashanthi, N.; Tripathy, H.; Hajra, R. N.; Raju, S.; Murugesan, S.; Saroja, S.

2017-11-01

In the present study, the feasibility of employing the indigenously developed ferroboron alloy (Fe-15 wt.%B) as an alternate neutron shield material in combination with 9Cr-based ferritic steel (P91) clad in future Indian fast breeder reactors (FBR), has been investigated from a metallurgical perspective. Towards this goal, a series of diffusion couple experiments have been conducted at three different temperatures namely, 600, 700 and 800 °C for time durations up to 5000 h. The thickness of interaction layer has been monitored using standard metallographic procedures. The experiments revealed that ferroboron/P91 combination exhibited a tendency to form complex intermetallic borides at the interface. The structural and microstructural characterization of the interface confirmed that the reaction layer consists predominantly of borides of Fe and Cr of type FeB, Fe2B, (Fe,Cr)2B and (Fe,Cr)B. The measured variation of interaction layer thickness as a function of time and temperature have been modelled in terms of diffusion mediated interaction. The growth kinetics of borided layer has followed the parabolic law at each temperature, and the apparent activation energy for boride layer formation is found to be of the order of 115 kJ mol-1. This indicates that the kinetics of boriding could be governed by diffusion of B into the P91 matrix. Based on the findings of present study, an extrapolative estimate of the clad attack thickness at 550 °C for 60 years of operating time has been made and it turns out to be 210 ± 15 μm, which is less than the clad thickness of FBR shielding subassembly (4 mm) [1]. Thus, this study confirms that at testing temperatures from 550 to 600 °C, the ferroboron/P91 steel combination can be safely employed for shielding subassembly applications in fast reactors.

Research and development of neodymium phosphate laser glass for high power laser application

NASA Astrophysics Data System (ADS)

Hu, Lili; He, Dongbing; Chen, Huiyu; Wang, Xin; Meng, Tao; Wen, Lei; Hu, Junjiang; Xu, Yongchun; Li, Shunguang; Chen, Youkuo; Chen, Wei; Chen, Shubin; Tang, Jingping; Wang, Biao

2017-01-01

Neodymium phosphate laser glass is a key optical element for high-power laser facility. In this work, the latest research and development of neodymium phosphate laser glass at the Shanghai Institute of Optics and Fine Mechanics (SIOM), China, is addressed. Neodymium phosphate laser glasses, N31, N41, NAP2, and NAP4, for high peak power and high average power applications have been developed. The properties of these glasses are presented and compared to those of other commercial neodymium phosphate laser glass from the Schott and Hoya companies and the Vavilov State Optical Institute (GOI), Russia. Continuous melting and edge cladding are the two key fabrication techniques that are used for the mass production of neodymium phosphate laser glass slabs. These techniques for the fabrication of large-aperture N31 neodymium phosphate laser glass slabs with low stress birefringence and residual reflectivity have been developed by us The effect of acid etching on the microstructure, optical transmission, and mechanical properties of NAP2 glass is also discussed.

Research and development of neodymium phosphate laser glass for high power laser application

NASA Astrophysics Data System (ADS)

Hu, Lili; He, Dongbing; Chen, Huiyu; Wang, Xin; Meng, Tao; Wen, Lei; Hu, Junjiang; Xu, Yongchun; Li, Shunguang; Chen, Youkuo; Chen, Wei; Chen, Shubin; Tang, Jingping; Wang, Biao

2016-12-01

Neodymium phosphate laser glass is a key optical element for high-power laser facility. In this work, the latest research and development of neodymium phosphate laser glass at the Shanghai Institute of Optics and Fine Mechanics (SIOM), China, is addressed. Neodymium phosphate laser glasses, N31, N41, NAP2, and NAP4, for high peak power and high average power applications have been developed. The properties of these glasses are presented and compared to those of other commercial neodymium phosphate laser glass from the Schott and Hoya companies and the Vavilov State Optical Institute (GOI), Russia. Continuous melting and edge cladding are the two key fabrication techniques that are used for the mass production of neodymium phosphate laser glass slabs. These techniques for the fabrication of large-aperture N31 neodymium phosphate laser glass slabs with low stress birefringence and residual reflectivity have been developed by us The effect of acid etching on the microstructure, optical transmission, and mechanical properties of NAP2 glass is also discussed.

Kinetics of electrolysis current reversal boriding of tool steels in a boron-containing oxychloride melt based on CaCl2

NASA Astrophysics Data System (ADS)

Chernov, Ya. B.; Filatov, E. S.

2017-08-01

The kinetics of thermal diffusion boriding in a melt based on calcium chloride with a boron oxide additive is studied using reversed current. The main temperature, concentration, and current parameters of the process are determined. The phase composition of the coating is determined by a metallographic method.

Search for New Superconductors for Energy and Power Applications

DTIC Science & Technology

2014-10-21

superconductors, borides , carbides, silicides, and chalcogenides. In addition, a number of thin film systems have been explored: A15s, superlattices, arrays of...YBa2Cu3O7 Bi2Se3 Eu-Si-C ErRh4B4 Bi2Sr2CaCu2O8 (UD, OD) Sb2Se3 V-Si-C (Ga,Mn)As CuO ZrSe2 Sm-Si-C Hf(FeCo)P Y1-xCaxCrO3 Fe-Te-Se BORIDES Hf-Fe-C-P...Physics, Warsaw, Poland Table III New superconductors, discovered by UCSD MURI team. BORIDES Tc (K) Nb0.9Zr0.1B 11.2 ZrNbxB 9.0 ZrVxB 9.0

Silicon carbide sintered body manufactured from silicon carbide powder containing boron, silicon and carbonaceous additive

NASA Technical Reports Server (NTRS)

Tanaka, Hidehiko

1987-01-01

A silicon carbide powder of a 5-micron grain size is mixed with 0.15 to 0.60 wt% mixture of a boron compound, i.e., boric acid, boron carbide (B4C), silicon boride (SiB4 or SiB6), aluminum boride, etc., and an aluminum compound, i.e., aluminum, aluminum oxide, aluminum hydroxide, aluminum carbide, etc., or aluminum boride (AlB2) alone, in such a proportion that the boron/aluminum atomic ratio in the sintered body becomes 0.05 to 0.25 wt% and 0.05 to 0.40 wt%, respectively, together with a carbonaceous additive to supply enough carbon to convert oxygen accompanying raw materials and additives into carbon monoxide.

Method of boronizing transition metal surfaces

DOEpatents

Koyama, Koichiro; Shimotake, Hiroshi

1983-01-01

A method is presented for preparing a boride layer on a transition metal substrate for use in corrosive environments or as a harden surface in machine applications. This method is particularly useful in treating current collectors for use within a high temperature and corrosive electrochemical cell environment. A melt of a alkali metal boride tetrafluoride salt including such as KF to lower its melting point is prepared including a dissolved boron containing material, for instance NiB, MnB.sub.2, or CrB.sub.2. A transition metal to be coated is immersed in the melt at a temperature of no more than 700.degree. C. and a surface boride layer of that transition metal is formed within a period of about 24 hours on the substrate surface.

Subminiature eddy current transducers for studying boride coatings

NASA Astrophysics Data System (ADS)

Dmitriev, S. F.; Ishkov, A. V.; Malikov, V. N.; Sagalakov, A. M.

2016-07-01

Strengthening of parts and units of machines, increased reliability and longer service life is an important task of modern mechanical engineering. The main objects of study in the work were selected steel 65G and 50HGA, wear-resistant boride coatings ternary system Fe-B-Fe n B which were investigated by scanning electron microscopy and eddy-current nondestructive methods.

Demonstration of Shear Localization in Ultrafine Grained Tungsten Alloys via Powder Metallurgy Processing Route

DTIC Science & Technology

2012-09-01

of a di-tungsten boride (W2B) phase was not detected in the nW-B sample, but the low concentration of boron may have made this phase undetectable by...Split Hopkinson Bar UFG ultrafine grained W2B di-tungsten boride XRD x-ray diffraction NO. OF NO. OF COPIES ORGANIZATION COPIES

Slater-Pauling behavior within quaternary intermetallic borides of the Ti{sub 3}Co{sub 5}B{sub 2} structure-type

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burghaus, Jens; Dronskowski, Richard, E-mail: drons@HAL9000.ac.rwth-aachen.d; Miller, Gordon J.

2009-10-15

First-principles, density-functional studies of several intermetallic borides of the general type M{sub 2}M'Ru{sub 5-n}Rh{sub n}B{sub 2} (n=0-5; M=Sc, Ti, Nb; M'=Fe, Co) show that the variation in saturation magnetic moment with valence-electron count follows a Slater-Pauling curve, with a maximum moment occurring typically at 66 valence electrons. The magnetic moments in these compounds occur primarily from the 3d electrons of the magnetically active M' sites, with some contribution from the Ru/Rh sites via magnetic polarization. Electronic DOS curves reveal that a rigid-band approach is a reasonable approximation for the estimation of saturation moments and the analysis of orbital interactions inmore » this family of complex borides. COHP analyses of the M'-M' orbital interactions indicate optimized interactions in the minority spin states for Co-containing phases, but strong bonding interactions remaining in Fe-containing phases. - Graphical abstract: Theoretically determined (spin-polarized LMTO-GGA) local magnetic moments as a function of the chemical valence Z for various intermetallic borides.« less

Superplastic behavior of two ultrahigh boron steels

NASA Astrophysics Data System (ADS)

Jiménez, J. A.; González-Doncel, G.; Acosta, P.; Ruano, O. A.

1994-06-01

The high-temperature deformation behavior of two ultrahigh boron steels containing 2.2 pct and 4.9 pct B was investigated. Both alloys were processed via powder metallurgy involving gas atomization and hot isostatic pressing (hipping) at various temperatures. After hipping at 700 °C, the Fe-2.2 pct B alloy showed a fine microstructure consisting of l- µm grains and small elongated borides (less than 1 µm) . At 1100 °C, a coarser microstructure with rounded borides was formed. This alloy was superplastic at 850 °C with stress exponents of about two and tensile elongations as high as 435 pct. The microstructure of the Fe-4.9 pct B alloy was similar to that of the Fe-2.2 pct B alloy showing, in addition, coarse borides. This alloy also showed low stress exponent values but lacked high tensile elongation (less than 65 pct), which was attributed to the presence of stress accumulation at the interface between the matrix and the large borides. A change in the activation energy value at the α-γ transformation temperature was seen in the Fe-2.2 pct B alloy. The plastic flow data were in agreement with grain boundary sliding and slip creep models.

Friction and wear of radiofrequency-sputtered borides, silicides, and carbides

NASA Technical Reports Server (NTRS)

Brainard, W. A.; Wheeler, D. R.

1978-01-01

The friction and wear properties of several refractory compound coatings were examined. These compounds were applied to 440 C bearing steel surfaces by radiofrequency (RF) sputtering. The refractory compounds were the titanium and molybdenum borides, the titanium and molybdenum silicides, and the titanium, molybdenum, and boron carbides. Friction testing was done with a pin-on-disk wear apparatus at loads from 0.1 to 5.0 newtons. Generally, the best wear properties were obtained when the coatings were bias sputtered onto 440 C disks that had been preoxidized. Adherence was improved because of the better bonding of the coatings to the iron oxide formed during preoxidation. As a class the carbides provided wear protection to the highest loads. Titanium boride coatings provided low friction and good wear properties to moderate loads.

Low temperature InP /Si wafer bonding using boride treated surface

NASA Astrophysics Data System (ADS)

Huang, Hui; Ren, Xiaomin; Wang, Wenjuan; Song, Hailan; Wang, Qi; Cai, Shiwei; Huang, Yongqing

2007-04-01

An approach for InP /Si wafer bonding based on boride-solution treatment was presented. The bonding energy is higher than the InP fracture energy by annealing at 280°C. An In0.53Ga0.47As/InP multiple-quantum-well (MQW) structure grown on InP was transferred onto Si substrate via the bonding process. X-ray diffraction and photoluminescence reveal that crystal quality of the bonded MQW was preserved. A thin B2O3-POx-SiO2 oxide layer of about 28nm thick at the bonding interface was detected. X-ray photoelectron spectroscopy and Raman analyses indicate that the formation of oxygen bridging bonds by boride treatment is responsible for the strong fusion obtained at such low temperature.

Method of boronizing transition metal surfaces

DOEpatents

Koyama, Koichiro; Shimotake, Hiroshi.

1983-08-16

A method is presented for preparing a boride layer on a transition metal substrate for use in corrosive environments or as a harden surface in machine applications. This method is particularly useful in treating current collectors for use within a high temperature and corrosive electrochemical cell environment. A melt of a alkali metal boride tetrafluoride salt including such as KF to lower its melting point is prepared including a dissolved boron containing material, for instance NiB, MnB[sub 2], or CrB[sub 2]. A transition metal to be coated is immersed in the melt at a temperature of no more than 700 C and a surface boride layer of that transition metal is formed within a period of about 24 hours on the substrate surface. 4 figs.

Taguchi Analysis on the Effect of Process Parameters on Densification During Spark Plasma Sintering of HfB2-20SiC (Preprint)

DTIC Science & Technology

2011-11-01

30 kN pressure and heating rate of 100 K/min. Introduction Boride , carbides and nitrides of the group IVB and VB transition metals are considered...10. Sciti D., Silvestroni L., Nygren M. Spark plasma sintering of Zr- and Hf- borides with decreasing amounts of MoSi2 as sintering aid Journal of

Phase identification in boron-containing powder metallurgy steel using EBSD in combination with EPMA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Ming-Wei, E-mail: mwwu@ntut.edu.tw; Cai, Wen-Zhang

2016-03-15

Boron (B) is extensively used to induce liquid phase sintering (LPS) in powder metallurgy (PM) steels and thereby increase the densification. The alloying elements in B-containing PM steels affect the boride phase, stability of the boride, the temperature of liquid formation, and the progress of LPS. However, the boride phase has not been systematically identified yet. The main objective of this study was to clarify the influences of alloying elements, including C, Cr, and Ni, on the boride phases using electron backscatter diffraction (EBSD) in combination with electron probe microanalysis (EPMA). Network structures consisting of ferrite, Fe{sub 2}B boride, andmore » Fe{sub 3}C carbide were extensively observed in the Fe–0.4B–0.5C steel. The portions of Fe{sub 2}B were sufficiently larger than those of Fe{sub 3}C, and Fe{sub 3}C was mostly distributed at the interfaces between ferrite and Fe{sub 2}B. Adding 1.5 wt.% Cr or 1.8 wt.% Ni to Fe–0.4B–0.5C steel completely changes the Fe{sub 2}B and Fe{sub 3}C phases to a M{sub 3}(B,C) phase, where M represents the metallic elements, including Fe, Cr, Mo, and Ni. Furthermore, Cr, Mo, B, and C atoms tend to concentrate on the M{sub 3}(B,C) phase, but Ni atoms do not. - Highlights: • Network structures consisting of ferrite, Fe{sub 2}B boride, and Fe{sub 3}C carbide were extensively observed in the Fe–0.4B–0.5C steel. • Adding 1.5 wt.% Cr or 1.8 wt.% Ni to Fe–0.4B–0.5C steel completely transforms the Fe{sub 2}B and Fe{sub 3}C phases to a M{sub 3}(B,C) phase. • Cr, Mo, B, and C atoms tend to concentrate on the M{sub 3}(B,C) phase, but Ni atoms do not.« less

Multifunctional Ceramic Nanostructured Coatings

DTIC Science & Technology

2010-12-01

silicon carbide composites // J. Europ. Cer. Soc. − 2004. − Vol. 24. − P. 2169−2179. 22. Yu. P. Udalov, E. E. Valova, S. S. Ordanian. Fabrication and...by the titanium and tungsten borides and carbides . The analysis was done using the X-ray and electron-optical methods. This information expands our...coating compositions should be based on limited solubility materials. Such systems include carbides , nitrides, borides and silicides based on

Structure of superhard tungsten tetraboride: A missing link between MB2 and MB12 higher borides

PubMed Central

Lech, Andrew T.; Turner, Christopher L.; Mohammadi, Reza; Tolbert, Sarah H.; Kaner, Richard B.

2015-01-01

Superhard metals are of interest as possible replacements with enhanced properties over the metal carbides commonly used in cutting, drilling, and wear-resistant tooling. Of the superhard metals, the highest boride of tungsten—often referred to as WB4 and sometimes as W1–xB3—is one of the most promising candidates. The structure of this boride, however, has never been fully resolved, despite the fact that it was discovered in 1961—a fact that severely limits our understanding of its structure–property relationships and has generated increasing controversy in the literature. Here, we present a new crystallographic model of this compound based on refinement against time-of-flight neutron diffraction data. Contrary to previous X-ray–only structural refinements, there is strong evidence for the presence of interstitial arrangements of boron atoms and polyhedral bonding. The formation of these polyhedra—slightly distorted boron cuboctahedra—appears to be dependent upon the defective nature of the tungsten-deficient metal sublattice. This previously unidentified structure type has an intermediary relationship between MB2 and MB12 type boride polymorphs. Manipulation of the fractionally occupied metal and boron sites may provide insight for the rational design of new superhard metals. PMID:25733870

Analysis of boron carbides' electronic structure

NASA Technical Reports Server (NTRS)

Howard, Iris A.; Beckel, Charles L.

1986-01-01

The electronic properties of boron-rich icosahedral clusters were studied as a means of understanding the electronic structure of the icosahedral borides such as boron carbide. A lower bound was estimated on bipolaron formation energies in B12 and B11C icosahedra, and the associated distortions. While the magnitude of the distortion associated with bipolaron formation is similar in both cases, the calculated formation energies differ greatly, formation being much more favorable on B11C icosahedra. The stable positions of a divalent atom relative to an icosahedral borane was also investigated, with the result that a stable energy minimum was found when the atom is at the center of the borane, internal to the B12 cage. If incorporation of dopant atoms into B12 cages in icosahedral boride solids is feasible, novel materials might result. In addition, the normal modes of a B12H12 cluster, of the C2B10 cage in para-carborane, and of a B12 icosahedron of reduced (D sub 3d) symmetry, such as is found in the icosahedral borides, were calculated. The nature of these vibrational modes will be important in determining, for instance, the character of the electron-lattice coupling in the borides, and in analyzing the lattice contribution to the thermal conductivity.

Electrochemical Corrosion Behavior of Spray-Formed Boron-Modified Supermartensitic Stainless Steel

NASA Astrophysics Data System (ADS)

Zepon, Guilherme; Nogueira, Ricardo P.; Kiminami, Claudio S.; Botta, Walter J.; Bolfarini, Claudemiro

2017-04-01

Spray-formed boron-modified supermartensitic stainless steel (SMSS) grades are alloys developed to withstand severe wear conditions. The addition of boron to the conventional chemical composition of SMSS, combined with the solidification features promoted by the spray forming process, leads to a microstructure composed of low carbon martensitic matrix reinforced by an eutectic network of M2B-type borides, which considerably increases the wear resistance of the stainless steel. Although the presence of borides in the microstructure has a very beneficial effect on the wear properties of the alloy, their effect on the corrosion resistance of the stainless steel was not comprehensively evaluated. The present work presents a study of the effect of boron addition on the corrosion resistance of the spray-formed boron-modified SMSS grades by means of electrochemical techniques. The borides fraction seems to have some influence on the repassivation kinetics of the spray-formed boron-modified SMSS. It was shown that the Cr content of the martensitic matrix is the microstructural feature deciding the corrosion resistance of this sort of alloys. Therefore, if the Cr content in the alloy is increased to around 14 wt pct to compensate for the boron consumed by the borides formation, the corrosion resistance of the alloy is kept at the same level of the alloy without boron addition.

A 6-GW NEODYMIUM GLASS LASER,

DTIC Science & Technology

A 6-GW neodymium glass laser with a simple phototropic Q-switch is described. The laser consists of three cylindrical rods in series, each 250 mm...operation (50-80 microsec. repetition frequency), the total output was 200 j. The use of a phototropic liquid switch and large-diameter neodymium glass

A Crossover from High Stiffness to High Hardness: The Case of Osmium and Its Borides

NASA Astrophysics Data System (ADS)

Bian, Yongming; Liu, Xiaomei; Li, Anhu; Liang, Yongcheng

2016-09-01

Transition-metal light-element compounds are currently raising great expectations for hard and superhard materials. Using the widely attracting osmium (Os) and its borides (OsB, Os2B3 and OsB2) as prototypes, we demonstrate by first-principles calculations that heavy transition metals, which possess high stiffness but low hardness, can be converted into highly hard materials by incorporating of light elements to form compounds. Such a crossover is a manifestation that the underlying sources of high stiffness and high hardness are fundamentally different. The stiffness is related to elastic deformation that is closely associated with valence electron density, whereas the hardness depends strongly on plastic deformation that is determined by bonding nature. Therefore, the incorporation of light atoms into transition metal should be a valid pathway of designing hard and superhard materials. This strategy is in principle also applicable to other transition-metal borides, carbides, and nitrides.

Investigation of the structure and properties of boron-containing coatings obtained by electron-beam treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krivezhenko, Dina S., E-mail: dinylkaa@yandex.ru; Drobyaz, Ekaterina A., E-mail: ekaterina.drobyaz@yandex.ru; Bataev, Ivan A., E-mail: ivanbataev@ngs.ru

2015-10-27

An investigation of surface-hardened materials obtained by cladding with an electron beam injected into the air atmosphere was carried out. Structural investigations of coatings revealed that an increase in boron carbide concentration in a saturating mixture contributed to a rise of a volume fraction of iron borides in coatings. The maximum hardened depth reached 2 mm. Hardened layers were characterized by the formation of heterogeneous structure which consisted of iron borides and titanium carbides distributed uniformly in the eutectic matrix. Areas of titanium boride conglomerations were detected. It was found that an increase in the boron carbide content led to anmore » enhancement in hardness of the investigated materials. Friction testing against loosely fixed abrasive particles showed that electron-beam cladding of powder mixtures containing boron carbides, titanium, and iron in air atmosphere allowed enhancing a resistance of materials hardened in two times.« less

Thermodynamical and thermoelectric properties of boron doped YPd{sub 3} and YRh{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dwivedi, Shalini; Sharma, Yamini, E-mail: sharma.yamini62@gmail.com; Sharma, Ramesh

2016-05-23

The structural, electronic, thermal, and optical properties of borides of cubic non-magnetic YX{sub 3} (X=Rh, Pd) compounds and their borides which crystallize in the AuCu{sub 3} structure have been studied using the density functional theory (DFT). The flat bands in the vicinity of E{sub F} which are associated with superconductivity appear in YPd{sub 3} and YRh{sub 3} band structures. However, the B s-states enhance the flat band only in YRh{sub 3}B. The optical properties clearly show that boron insertion modifies the absorption and transmittance. The YX{sub 3} alloys and their borides exhibit valuable changes in the thermopower and ZT. Itmore » is observed that the properties of the Y-X intermetallics change significantly for the Y-Rh and Y-Pd alloys and the presence of single boron atom modifies the properties to a great extent.« less

Magnetization Analysis of Magnesium Boride Wires

NASA Astrophysics Data System (ADS)

Cave, J. R.; Zhu, W.

2006-03-01

Cycled applied field magnetization curves contain a wealth of information on critical current density and flux pinning that is not commonly exploited. Detailed magnetization data for magnesium boride wire cores have been analyzed for critical state model consistency. The iron-sheathed silicon nitride doped magnesium boride wires were prepared from pure magnesium and boron powders with nano-scale silicon nitride additions (MgB2-x(Si3N4)x/7 with x = 0 - 0.4). A subsequent short annealing heat treatment, 800 degrees C and of 1 hour duration in Argon, was applied to create the desired phase. Magnetization critical current densities were up to ˜340 kA/cm2 at 5K and 1T. Major and minor loop analysis will be described, for field sweeps up to 3 tesla at fixed temperatures and for temperature sweeps from 5K to 45K in fixed fields, with respect to parameters describing the critical state model.

Investigation of the structure and properties of boron-containing coatings obtained by electron-beam treatment

NASA Astrophysics Data System (ADS)

Krivezhenko, Dina S.; Drobyaz, Ekaterina A.; Bataev, Ivan A.; Chuchkova, Lyubov V.

2015-10-01

An investigation of surface-hardened materials obtained by cladding with an electron beam injected into the air atmosphere was carried out. Structural investigations of coatings revealed that an increase in boron carbide concentration in a saturating mixture contributed to a rise of a volume fraction of iron borides in coatings. The maximum hardened depth reached 2 mm. Hardened layers were characterized by the formation of heterogeneous structure which consisted of iron borides and titanium carbides distributed uniformly in the eutectic matrix. Areas of titanium boride conglomerations were detected. It was found that an increase in the boron carbide content led to an enhancement in hardness of the investigated materials. Friction testing against loosely fixed abrasive particles showed that electron-beam cladding of powder mixtures containing boron carbides, titanium, and iron in air atmosphere allowed enhancing a resistance of materials hardened in two times.

Q-Switching in a Neodymium Laser

ERIC Educational Resources Information Center

Holgado, Warein; Sola, Inigo J.; Jarque, Enrique Conejero; Jarabo, Sebastian; Roso, Luis

2012-01-01

We present a laboratory experiment for advanced undergraduate or graduate laser-related classes to study the performance of a neodymium laser. In the experiment, the student has to build the neodymium laser using an open cavity. After that, the cavity losses are modulated with an optical chopper located inside, so the Q-switching regime is…

Origin of the Sudbury Complex by meteoritic impact: Neodymium isotopic evidence

USGS Publications Warehouse

Faggart, B.E.; Basu, A.R.; Tatsumoto, M.

1985-01-01

Samarium-neodymium isotopic data on whole rocks and minerals of the Sudbury Complex in Canada gave an igneous crystallization age of 1840 ?? 21 ?? 106 years. The initial epsilon neodymium values for 15 whole rocks are similar to those for average upper continental crust, falling on the crustal trend of neodymium isotopic evolution as defined by shales. The rare earth element concentration patterns of Sudbury rocks are also similar to upper crustal averages. These data suggest that the Sudbury Complex formed from melts generated in the upper crust and are consistent with a meteoritic impact.

Crystal structures and compressibility of novel iron borides Fe{sub 2}B{sub 7} and Fe{sub x}B{sub 50} synthesized at high pressure and high temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bykova, E., E-mail: elena.bykova@uni-bayreuth.de; Laboratory of Crystallography, University of Bayreuth, D-95440 Bayreuth; Gou, H.

2015-10-15

We present here a detailed description of the crystal structures of novel iron borides, Fe{sub 2}B{sub 7} and Fe{sub x}B{sub 50} with various iron content (x=1.01(1), 1.04(1), 1.32(1)), synthesized at high pressures and high temperatures. As revealed by high-pressure single-crystal X-ray diffraction, the structure of Fe{sub 2}B{sub 7} possesses short incompressible B–B bonds, which make it as stiff as diamond in one crystallographic direction. The volume compressibility of Fe{sub 2}B{sub 7} (the bulk modulus K{sub 0}= 259(1.8) GPa, K{sub 0}′= 4 (fixed)) is even lower than that of FeB{sub 4} and comparable with that of MnB{sub 4}, known for highmore » bulk moduli among 3d metal borides. Fe{sub x}B{sub 50} adopts the structure of the tetragonal δ-B, in which Fe atoms occupy an interstitial position. Fe{sub x}B{sub 50} does not show considerable anisotropy in the elastic behavior. - Graphical abstract: Crystal structures of novel iron borides, Fe{sub 2}B{sub 7} and Fe{sub x}B{sub 50} (x=1.01(1), 1.04(1), 1.32(1)). - Highlights: • Novel iron borides, Fe{sub 2}B{sub 7} and Fe{sub x}B{sub 50}, were synthesized under HPHT conditions. • Fe{sub 2}B{sub 7} has a unique orthorhombic structure (space group Pbam). • Fe{sub 2}B{sub 7} possesses short incompressible B–B bonds that results in high bulk modulus. • Fe{sub x}B{sub 50} adopts the structure of the tetragonal δ-B composed of B{sub 12} icosahedra. • In Fe{sub x}B{sub 50} intraicosahedral bonds are stiffer than intericosahedral ones.« less

Synthesis, characterization and photocatalytic activity of neodymium carbonate and neodymium oxide nanoparticles

NASA Astrophysics Data System (ADS)

Pourmortazavi, Seied Mahdi; Rahimi-Nasrabadi, Mehdi; Aghazadeh, Mustafa; Ganjali, Mohammad Reza; Karimi, Meisam Sadeghpour; Norouzi, Parviz

2017-12-01

This work focuses on the application of an orthogonal array design to the optimization of the facile direct carbonization reaction for the synthesis of neodymium carbonate nanoparticles, were the product particles are prepared based on the direct precipitation of their ingredients. To optimize the method the influences of the major operating conditions on the dimensions of the neodymium carbonate particles were quantitatively evaluated through the analysis of variance (ANOVA). It was observed that the crystalls of the carbonate salt can be synthesized by controlling neodymium concentration and flow rate, as well as reactor temperature. Based on the results of ANOVA, 0.03 M, 2.5 mL min-1 and 30 °C are the optimum values for the above-mentioend parameters and controlling the parameters at these values yields nanoparticles with the sizes of about of 31 ± 2 nm. The product of this former stage was next used as the feed for a thermal decomposition procedure which yielding neodymium oxide nanoparticles. The products were studied through X-ray diffraction (XRD), SEM, TEM, FT-IR and thermal analysis techniques. In addition, the photocatalytic activity of dyspersium carbonate and dyspersium oxide nanoparticles were investigated using degradation of methyl orange (MO) under ultraviolet light.

The effect of melt refining upon inclusions in aluminum

NASA Astrophysics Data System (ADS)

Simensen, C. J.

1982-03-01

A series of aluminum melts has been refined with respect to inclusions by use of ALCOA 469, FILD, or SNIF. The content and size distribution of inclusions in the original-and the refined melts-have been measured by use of neutron activation (oxygen content), gas chromatography (carbide content), sedimentation analysis, and dissolution of metal in hydrochloric acid and subsequent analysis of oxides by means of a Coulter Counter. All the units tested have a beneficial effect and decrease the inclusion content, but the number of analyses are too few to make general conclusions. However, for melts cleaned by use of SNIF, it was found that oxides larger than 50 μm in cross section and borides larger than 20 μm in diameter were removed, while the smaller borides were agglomerated only. The effect of FILD and ALCOA 469 upon the melt tested was removal of borides larger than 5-10 μ m and oxides larger than 15μm in diameter, respectively.

Interfacial reactions in borsic/Ti-3Al-2-1/2V composite

NASA Technical Reports Server (NTRS)

Rao, V. B.; Houska, C. R.; Unnam, J.; Brewer, W. D.; Tenney, D. R.

1979-01-01

The paper provides a detailed X-ray characterization of a borsic/Ti-3Al-2-1/2V composite, and to correlate the relative intensities of the reaction products with the mechanical properties. Based on X-ray integrated intensity data two stages of interface reactions were identified: during the first stage there is a simultaneous interdiffusion of Si, C, and Ti atoms at the filament/matrix interface resulting in the formation of Ti5Si3, TiSi and small amounts of TiSi2 and TiC. The second stage is associated with considerable TiSi2 and boride formation. It appears that the alpha-phase of Ti is more reactive in forming silicides and borides than the beta-phase. The silicide intensities and the reaction zone thicknesses are shown to be directly related to the reduction of the ultimate tensile strength by thermal degradation, and the results indicate that silicide reaction products are as detrimental to strength as the borides.

A Simple Kinetic Model for the Growth of Fe2B Layers on AISI 1026 Steel During the Powder-pack Boriding

NASA Astrophysics Data System (ADS)

Flores-Rentería, M. A.; Ortiz-Domínguez, M.; Keddam, M.; Damián-Mejía, O.; Elias-Espinosa, M.; Flores-González, M. A.; Medina-Moreno, S. A.; Cruz-Avilés, A.; Villanueva-Ibañez, M.

2015-02-01

This work focused on the determination of boron diffusion coefficient through the Fe2B layers on AISI 1026 steel using a mathematical model. The suggested model solves the mass balance equation at the (Fe2B/substrate) interface. This thermochemical treatment was carried out in the temperature range of 1123-1273 K for a treatment time ranging from 2 to 8 h. The generated boride layers were characterized by different experimental techniques such as light optical microscopy, scanning electron microscopy, XRD analysis and the Daimler-Benz Rockwell-C indentation technique. As a result, the boron activation energy for AISI 1026 steel was estimated as 178.4 kJ/mol. Furthermore, this kinetic model was validated by comparing the experimental Fe2B layer thickness with the predicted one at a temperature of 1253 K for 5 h of treatment. A contour diagram relating the layer thickness to the boriding parameters was proposed to be used in practical applications.

Amorphous nickel boride membrane on a platinum-nickel alloy surface for enhanced oxygen reduction reaction.

PubMed

He, Daping; Zhang, Libo; He, Dongsheng; Zhou, Gang; Lin, Yue; Deng, Zhaoxiang; Hong, Xun; Wu, Yuen; Chen, Chen; Li, Yadong

2016-08-09

The low activity of the oxygen reduction reaction in polymer electrolyte membrane fuel cells is a major barrier for electrocatalysis, and hence needs to be optimized. Tuning the surface electronic structure of platinum-based bimetallic alloys, a promising oxygen reduction reaction catalyst, plays a key role in controlling its interaction with reactants, and thus affects the efficiency. Here we report that a dealloying process can be utilized to experimentally fabricate the interface between dealloyed platinum-nickel alloy and amorphous nickel boride membrane. The coating membrane works as an electron acceptor to tune the surface electronic structure of the platinum-nickel catalyst, and this composite catalyst composed of crystalline platinum-nickel covered by amorphous nickel boride achieves a 27-times enhancement in mass activity relative to commercial platinum/carbon at 0.9 V for the oxygen reduction reaction performance. Moreover, this interactional effect between a crystalline surface and amorphous membrane can be readily generalized to facilitate the 3-times higher catalytic activity of commercial platinum/carbon.

Influence of heat treatment on microstructure and hot crack susceptibility of laser-drilled turbine blades made from Rene 80

DOE Office of Scientific and Technical Information (OSTI.GOV)

Osterle, W.; Krause, S.; Moelders, T.

2008-11-15

Turbine components from conventionally cast nickel-base alloy Rene 80 show different hot cracking susceptibilities depending on their heat treatment conditions leading to slightly different microstructures. Electron probe micro-analysis, focused ion beam technique and analytical transmission electron microscopy were applied to reveal and identify grain boundary precipitates and the {gamma}-{gamma}'-microstructure. The distribution of borides along grain boundaries was evaluated statistically by quantitative metallography. The following features could be correlated with an increase of cracking susceptibility: i) Increasing grain size, ii) increasing fraction of grain boundaries with densely spaced borides, iii) lack of secondary {gamma}'-particles in matrix channels between the coarse cuboidalmore » {gamma}'-precipitates. The latter feature seems to be responsible for linking-up of cracked grain boundary precipitates which occurred as an additional cracking mechanism after one heat treatment, whereas decohesion at the boride-matrix-interface in the heat affected zone of laser-drilled holes was observed for both heat treatments.« less

Method of making an icosahedral boride structure

DOEpatents

Hersee, Stephen D.; Wang, Ronghua; Zubia, David; Aselage, Terrance L.; Emin, David

2005-01-11

A method for fabricating thin films of an icosahedral boride on a silicon carbide (SiC) substrate is provided. Preferably the icosahedral boride layer is comprised of either boron phosphide (B.sub.12 P.sub.2) or boron arsenide (B.sub.12 As.sub.2). The provided method achieves improved film crystallinity and lowered impurity concentrations. In one aspect, an epitaxially grown layer of B.sub.12 P.sub.2 with a base layer or substrate of SiC is provided. In another aspect, an epitaxially grown layer of B.sub.12 As.sub.2 with a base layer or substrate of SiC is provided. In yet another aspect, thin films of B.sub.12 P.sub.2 or B.sub.12 As.sub.2 are formed on SiC using CVD or other vapor deposition means. If CVD techniques are employed, preferably the deposition temperature is above 1050.degree. C., more preferably in the range of 1100.degree. C. to 1400.degree. C., and still more preferably approximately 1150.degree. C.

Microstructure and mechanical properties of Ni and Fe-base boride-dispersion-strengthened microcrystalline alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wade, C.S.; Park, H.G.; Hoagland, R.G.

This paper considers the relation between microstructure and mechanical properties of two Ni-base and two Fe-base Boride-Dispersion-Strengthened Microcrystalline (BDSM) alloys. In these very fine grained materials the borides were primarily Cr, Mo, and MoFe in a fcc matrix in three of the alloys, and a bcc in one of the Fe-base alloys. Strength data and resistance to stress corrosion cracking are reported and, in the latter case, extraordinary resistance to SCC in NaCl, Na{sub 2}S{sub 2}O{sub 3} and boiling MgCl{sub 2} environments was observed in every case. The fcc BDSM alloys also demonstrated excellent thermal stability in terms of strengthmore » and fracture roughness up to 1000 C. The bcc alloy suffered severe loss of toughness. The fracture mode involved ductile rupture in all alloys and they display a reasonably linear correlation between K{sub Ic} and the square root of particle spacing.« less

Electrolytic production of neodymium without perfluorinated carbon compounds on the offgases

DOEpatents

Keller, R.; Larimer, K.T.

1998-09-22

A method is described for producing neodymium in an electrolytic cell without formation of perfluorinated carbon gases (PFCs), the method comprising the steps of providing an electrolyte in the electrolytic cell and providing an anode in an anode region of the electrolyte and providing a cathode in a cathode region of the electrolytic cell. Dissolving an oxygen-containing neodymium compound in the electrolyte in the anode region and maintaining a more intense electrolyte circulation in the anode region than in the cathode region. Passing an electrolytic current between said anode and said cathode and depositing neodymium metal at the cathode, preventing the formation of perfluorinated carbon gases by limiting anode over voltage. 4 figs.

Electrolytic production of neodymium without perfluorinated carbon compounds on the offgases

DOEpatents

Keller, Rudolf; Larimer, Kirk T.

1998-01-01

A method of producing neodymium in an electrolytic cell without formation of perfluorinated carbon gases (PFCs), the method comprising the steps of providing an electrolyte in the electrolytic cell and providing an anode in an anode region of the electrolyte and providing a cathode in a cathode region of the electrolytic cell. Dissolving an oxygen-containing neodymium compound in the electrolyte in the anode region and maintaining a more intense electrolyte circulation in the anode region than in the cathode region. Passing an electrolytic current between said anode and said cathode and depositing neodymium metal at the cathode, preventing the formation of perfluorinated carbon gases by limiting anode over voltage.

Magnetic properties and magnetic hardening mechansim of Pt-Co-B alloys

NASA Technical Reports Server (NTRS)

Qiu, Ning; Flanagan, F.; Wittig, James E.

1994-01-01

The intrinsic coercivity is found to be maximized in the Pt42Co45B13 ternary alloy which is undercooled and rapidly solidified (quenched using a 70 m/s wheel speed after undercooling), and then annealed (800 C for 2400 min). The same alloy, processed at slower cooling rates and annealed in the same way, has a much larger scale microstructure and a much lower resulting magnetic coercivity. The microstructure which would optimize the coercitvity of this coercivity of this ternary alloy is a completely ordered L1(sub zero) Pt-Co matrix with a submicron magnetic single-domion Co-boride precipitate. The L1(sub zero) phase is highly anistropic magnetically while the Co-boride precipate is somewhat less so. Annealing treatments designed to produced single-domain Co-boride precipitates enhance the coercivity. This suggests that the refined microstructures is responsible for the high coercivities found in the rapidly solidified and annealed alloy. The magnetic domain wall thickness for a Co-boride precipitate is determined from both experimental observation and theoretical calculation in order to evaluate its influence on the coercivity of the alloy. The effects of the pinning of domain walls and the barrier to the nucleation of reverse domains on the coercivity are discussed. Both microstrucutral analysis and theoretical calculation indicate that the high coercivities in the Pt42Co45B13 alloy are due to the difficult nucleation of reverse magnetic domains.

Neodymium Magnets.

ERIC Educational Resources Information Center

Wida, Sam

1992-01-01

Uses extremely strong neodymium magnets to demonstrate several principles of physics including electromagnetic induction, Lenz's Law, domain theory, demagnetization, the Curie point, and magnetic flux lines. (MDH)

Perpendicular magnetic anisotropy in amorphous NdxCo1 -x thin films studied by x-ray magnetic circular dichroism

NASA Astrophysics Data System (ADS)

Cid, R.; Alameda, J. M.; Valvidares, S. M.; Cezar, J. C.; Bencok, P.; Brookes, N. B.; Díaz, J.

2017-06-01

The origin of perpendicular magnetic anisotropy (PMA) in amorphous NdxCo1 -x thin films is investigated using x-ray magnetic circular dichroism (XMCD) spectroscopy at the Co L2 ,3 and Nd M4 ,5 edges. The magnetic orbital and spin moments of the 3 d cobalt and 4 f neodymium electrons were measured as a function of the magnetic field orientation, neodymium concentration, and temperature. In all the studied samples, the magnetic anisotropy of the neodymium subnetwork is always oriented perpendicular to the plane, whereas the anisotropy of the orbital moment of cobalt is in the basal plane. The ratio Lz/Sz of the neodymium 4 f orbitals changes with the sample orientation angle, being higher and closer to the atomic expected value at normal orientation and smaller at grazing angles. This result is well explained by assuming that the 4 f orbital is distorted by the effect of an anisotropic crystal field when it is magnetized along its hard axis, clearly indicating that the 4 f states are not rotationally invariant. The magnetic anisotropy energy associated to the neodymium subnetwork should be proportional to this distortion, which we demonstrate is accessible by applying the XMCD sum rules for the spin and intensity at the Nd M4 ,5 edges. The analysis unveils a significant portion of neodymium atoms magnetically uncoupled to cobalt, i.e., paramagnetic, confirming the inhomogeneity of the films and the presence of a highly disordered neodymium rich phase already detected by extended x-ray-absorption fine structure (EXAFS) spectroscopy. The presence of these inhomogeneities is inherent to the evaporation preparation method when the chosen concentration in the alloy is far from its eutectic concentrations. An interesting consequence of the particular way in which cobalt and neodymium segregates in this system is the enhancement of the cobalt spin moment which reaches 1.95 μB in the sample with the largest segregation.

Development of High Temperature Superconducting Josephson Junction Device Technology

DTIC Science & Technology

1998-07-09

neodymium gallate , cerium oxide-buffered sapphire, and lanthanum aluminate, are not ideal for an in situ thallium cuprate junction technology. Moreover...determined that the standard HTS substrates, neodymium gallate , cerium oxide-buffered sapphire, and lanthanum aluminate, are not ideal for an in situ...2.2.1. Deposition Uniformity 10 2.2.2. Radiative Element 12 2.3. SUBSTRATES 13 2.3.1. Neodymium gallate 14 2.3.2. Cerium Oxide-Buffered Sapphire 16

Electroplating of the superconductive boride MgB2 from molten salts

NASA Astrophysics Data System (ADS)

Abe, Hideki; Yoshii, Kenji; Nishida, Kenji; Imai, Motoharu; Kitazawa, Hideaki

2005-02-01

An electroplating technique of the superconductive boride MgB2 onto graphite substrates is reported. Films of MgB2 with a thickness of tens micrometer were fabricated on the planar and curved surfaces of graphite substrates by means of electrolysis on a mixture of magnesium chloride, potassium chloride, sodium chloride, and magnesium borate fused at 600 °C under an Ar atmosphere. The electrical resistivity and magnetization measurements revealed that the electroplated MgB2 films undergo a superconducting transition with the critical temperature (Tc) of 36 K.

Fine structure of the K X-ray absorption spectra of titanium in some hydrides, borides, and silicides (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vainshtein, �. E.; Zhurakovskii, E. A.

1959-08-01

X-ray spectral analyses confirmed the hypothesis on the metal-like state of hydrogen in tithnium hydrides. Experiments with titunium borides and silicides indicate the special character and degree of the 3d--level participation in the metallic'' bond between the atoms of various complexes. The structure of metalloid elements becomes more complicated with an increase in the specific number of boron and silicon atoms and the bond between the atoms tends to become covalent. (R.V.J.)

History of ``NANO''-Scale VERY EARLY Solid-State (and Liquid-State) Physics/Chemistry/Metallurgy/ Ceramics; Interstitial-Alloys Carbides/Nitrides/Borides/...Powders and Cermets, Rock Shocks, ...

NASA Astrophysics Data System (ADS)

Maiden, Colin; Siegel, Edward

History of ``NANO'': Siegel-Matsubara-Vest-Gregson[Mtls. Sci. and Eng. 8, 6, 323(`71); Physica Status Solidi (a)11,45(`72)] VERY EARLY carbides/nitrides/borides powders/cermets solid-state physics/chemistry/metallurgy/ ceramics FIRST-EVER EXPERIMENTAL NANO-physics/chemistry[1968 ->Physica Status Solidi (a)11,45(`72); and EARLY NANO-``physics''/NANO-``chemistry'' THEORY(after: Kubo(`62)-Matsubara(`60s-`70s)-Fulde (`65) [ref.: Sugano[Microcluster-Physics, Springer('82 `98)

A green separation strategy for neodymium (III) from cobalt (II) and nickel (II) using an ionic liquid-based aqueous two-phase system.

PubMed

Chen, Yuehua; Wang, Huiyong; Pei, Yuanchao; Wang, Jianji

2018-05-15

It is significant to develop sustainable strategies for the selective separation of rare earth from transition metals from fundamental and practical viewpoint. In this work, an environmentally friendly solvent extraction approach has been developed to selectively separate neodymium (III) from cobalt (II) and nickel (II) by using an ionic liquid-based aqueous two phase system (IL-ATPS). For this purpose, a hydrophilic ionic liquid (IL) tetrabutylphosphonate nitrate ([P 4444 ][NO 3 ]) was prepared and used for the formation of an ATPS with NaNO 3 . Binodal curves of the ATPSs have been determined for the design of extraction process. The extraction parameters such as contact time, aqueous phase pH, content of phase-formation components of NaNO 3 and the ionic liquid have been investigated systematically. It is shown that under optimal conditions, the extraction efficiency of neodymium (III) is as high as 99.7%, and neodymium (III) can be selectively separated from cobalt (II) and nickel (II) with a separation factor of 10 3 . After extraction, neodymium (III) can be stripped from the IL-rich phase by using dilute aqueous sodium oxalate, and the ILs can be quantitatively recovered and reused in the next extraction process. Since [P 4444 ][NO 3 ] works as one of the components of the ATPS and the extractant for the neodymium, no organic diluent, extra etractant and fluorinated ILs are used in the separation process. Thus, the strategy described here shows potential in green separation of neodymium from cobalt and nickel by using simple IL-based aqueous two-phase system. Copyright © 2018 Elsevier B.V. All rights reserved.

Synthesis and Characterization of Low-Cost Superhard Transition-Metal Borides

NASA Astrophysics Data System (ADS)

Kaner, Richard

2013-06-01

The increasing demand for high-performance cutting and forming tools, along with the shortcomings of traditional tool materials such as diamond (unable to cut ferrous materials), cubic boron nitride (expensive) and tungsten carbide (relatively-low hardness), has motivated the search for new superhard materials for these applications. This has led us to a new class of superhard materials, dense refractory transition-metal borides, which promise to address some of the existing problems of conventional superhard materials. For example, we have synthesized rhenium diboride (ReB2) using arc melting at ambient pressure. This superhard material has demonstrated an excellent electrical conductivity and superior mechanical properties, including a Vickers hardness of 48.0 GPa (under an applied load of 0.49 N). To further increase the hardness and lower the materials costs, we have begun exploring high boron content metal borides including tungsten tetraboride (WB4) . We have synthesized WB4 by arc melting and studied its hardness and high-pressure behavior. With a similar Vickers hardness (43.3 GPa under a load of 0.49 N) and bulk modulus (326-339 GPa) to ReB2, WB4 offers a lower cost alternative and has the potential to be used in cutting tools. To further enhance the hardness of this superhard metal, we have created the binary and ternary solid solutions of WB4 with Cr, Mn and Ta, the results of which show a hardness increase of up to 20 percent. As with other metals, these metallic borides can be readily cut and shaped using electric discharge machining (EDM).

Microstructure of Vacuum-Brazed Joints of Super-Ni/NiCr Laminated Composite Using Nickel-Based Amorphous Filler Metal

NASA Astrophysics Data System (ADS)

Ma, Qunshuang; Li, Yajiang; Wu, Na; Wang, Juan

2013-06-01

Vacuum brazing of super-Ni/NiCr laminated composite and Cr18-Ni8 stainless steel was carried out using Ni-Cr-Si-B amorphous filler metal at 1060, 1080, and 1100 °C, respectively. Microstructure and phase constitution were investigated by means of optical and scanning electron microscopy, energy-dispersive spectroscopy, x-ray diffraction, and micro-hardness tester. When brazed at 1060-1080 °C, the brazed region can be divided into two distinct zones: isothermally solidified zone (ISZ) consisting of γ-Ni solid solution and athermally solidified zone (ASZ) consisting of Cr-rich borides. Micro-hardness of the Cr-rich borides formed in the ASZ was as high as 809 HV50 g. ASZ decreased with increase of the brazing temperature. Isothermal solidification occurred sufficiently at 1100 °C and an excellent joint composed of γ-Ni solid solution formed. The segregation of boron from ISZ to residual liquid phase is the reason of Cr-rich borides formed in ASZ. The formation of secondary precipitates in diffusion-affected zone is mainly controlled by diffusion of B.

Microstructure and High Temperature Mechanical Property of Fe-Cr-B Based Metal/Ceramic Composite Manufactured by Metal Injection Molding Process

NASA Astrophysics Data System (ADS)

Lee, Kee-Ahn; Gwon, Jin-Han; Yoon, Tae-Sik

2018-03-01

This study investigated the microstructure and the room and high temperature mechanical properties of Fe-Cr-B alloy manufactured by metal injection molding. In addition, hot isostatic pressing was performed to increase the density of the material, and a comparison of properties was made. Microstructural observation confirmed a bi-continuous structure composed of a three-dimensional network of α-Fe phase and (Cr,Fe)2B phase. The HIPed specimen featured a well-formed adhesion between the α-Fe phase and boride, and the number of fine pores was significantly reduced. The tensile results confirmed that the HIPed specimen (RT to 900 °C) had higher strengths compared to the as-sintered specimen, and the change of elongation starting from 700 °C was significantly greater in the HIPed specimen. Fractography suggested that cracks propagated mostly along the interface between the α-Fe matrix and boride in the as-sintered specimen, while direct fracture of boride was observed in addition to interface separation in the HIPed specimen.

Antioxidant protection mechanism of chick hepatic mitochondria exposed to lanthanum chloride & neodymium chloride treatment.

PubMed

Ghosh, N; Chattopadhyay, D; Chatterjee, G C

1991-05-01

Acute lanthanum chloride (250 mg/kg body wt) and neodymium chloride (200 mg/kg body wt) administrations resulted in significant enhancement of glutathione level in chick hepatic mitochondria. However, glutathione-s-transferase activity was depressed. There was no alteration in the activity of glutathione reductase. Activity of glucose-6-phosphate dehydrogenase was not altered under lanthanum and neodymium treatment. There was a significant enhancement of intramitochondrial glutathione peroxidase and superoxide dismutase. Lipid peroxidation remains the same as control group of animals.

Electrically conductive containment vessel for molten aluminum

DOEpatents

Holcombe, C.E.; Scott, D.G.

1984-06-25

The present invention is directed to a containment vessel which is particularly useful in melting aluminum. The vessel of the present invention is a multilayered vessel characterized by being electrically conductive, essentially nonwettable by and nonreactive with molten aluminum. The vessel is formed by coating a tantalum substrate of a suitable configuration with a mixture of yttria and particulate metal 10 borides. The yttria in the coating inhibits the wetting of the coating while the boride particulate material provides the electrical conductivity through the vessel. The vessel of the present invention is particularly suitable for use in melting aluminum by ion bombardment.

Electrically conductive containment vessel for molten aluminum

DOEpatents

Holcombe, Cressie E.; Scott, Donald G.

1985-01-01

The present invention is directed to a containment vessel which is particularly useful in melting aluminum. The vessel of the present invention is a multilayered vessel characterized by being electrically conductive, essentially nonwettable by and nonreactive with molten aluminum. The vessel is formed by coating a tantalum substrate of a suitable configuration with a mixture of yttria and particulate metal borides. The yttria in the coating inhibits the wetting of the coating while the boride particulate material provides the electrical conductivity through the vessel. The vessel of the present invention is particularly suitable for use in melting aluminum by ion bombardment.

Phase equilibrium in system Ti-Si-C-B and synthesis of MAX phase layers in vacuum under the influence of electron beam

NASA Astrophysics Data System (ADS)

Smirnyagina, N. N.; Khaltanova, V. M.; Dasheev, D. E.; Lapina, A. E.

2017-05-01

Composite layers on the basis of carbides and borides the titan and silicon on titanic alloy VТ-1 are generated at diffused saturation by electron beam treatment in vacuum. Formation in a composite of MAX phase Ti3SiC2 is shown. Thermodynamic research of phase equilibrium in systems Ti-Si-C and Ti-B-C in the conditions of high vacuum is executed. The thermodynamics, formation mechanisms of superfirm layers borides and carbides of the titan and silicon are investigated.

Brazing Inconel 625 Using Two Ni/(Fe)-Based Amorphous Filler Foils

NASA Astrophysics Data System (ADS)

Chen, Wen-Shiang; Shiue, Ren-Kae

2012-07-01

For MBF-51 filler, the brazed joint consists of interfacial grain boundary borides, coarse Nb6Ni16Si7, and Ni/Cr-rich matrix. In contrast, the VZ-2106 brazed joint is composed of interfacial Nb6Ni16Si7 precipitates as well as grain boundary borides, coarse Nb6Ni16Si7, and Ni/Cr/Fe-rich matrix. The maximum tensile strength of 443 MPa is obtained from the MBF-51 brazed specimen. The tensile strengths of VZ-2106 brazed joints are approximately 300 MPa. Both amorphous filler foils demonstrate potential in brazing IN-625 substrate.

Isotope enrichment by frequency-tripled temperature tuned neodymium laser photolysis of formaldehyde

DOEpatents

Marling, John B.

1977-01-01

Enrichment of carbon, hydrogen and/or oxygen isotopes by means of isotopically selective photo-predissociation of formaldehyde is achieved by irradiation provided by a frequency-tripled, temperature tuned neodymium laser.

[The first experience with the concurrent effect of YAG-neodymium and YAG-erbium laser on experimental animal tissues and the possibility of its use in surgery].

PubMed

Roshal', L M; Gorbatova, N E; Livshits, Iu L; Parkhomenko, Iu G; Osiko, V V; Danileĭko, Iu K; Sidorin, A V; Tylaĭkova, T B; Ivanov, A D

1991-08-01

To guarantee the necessary rate of cutting live tissues with adequate hemostasis along the line of the incision, the authors studied isolated and joint effect of radiations of AIG-neodymium and AIG-erbium lasers on the tissues of laboratory animals. The possibility of accomplishing intraoperative hemostasis on the parenchymal organs was studied in experiments with AIG-neodymium laser. A good dissection effect in cutting various tissues was produced in the second series of experiments with AIG-erbium laser. The simultaneous action of AIG-neodymium and AIG-erbium beams converged at one point on the surface of the biological object was studied in the third series of experiments. It was found that the effect ensures a good dissection of tissues with sufficient hemostasis. The results of dynamic morphological studies are shown. The possibility of using the device in surgery is discussed.

Synthesis, Structure, and Properties of Refractory Hard-Metal Borides

NASA Astrophysics Data System (ADS)

Lech, Andrew Thomas

As the limits of what can be achieved with conventional hard compounds, such as tungsten carbide, are nearing reach, super-hard materials are an area of increasing industrial interest. The refractory hard metal borides, such as ReB2 and WB4, offer an increasingly attractive alternative to diamond and cubic boron nitride as a next-generation tool material. In this Thesis, a thorough discussion is made of the progress achieved by our laboratory towards understanding the synthesis, structure, and properties of these extremely hard compounds. Particular emphasis is placed on structural manipulation, solid solution formation, and the unique crystallographic manifestations of what might also be called "super-hard metals".

Microscale Demonstration of the Paramagnetism of Liquid Oxygen with a Neodymium Magnet

ERIC Educational Resources Information Center

Mattson, Bruce

2007-01-01

A microscale classroom demonstration of the paramagnetic behavior of various samples of liquid oxygen with neodymium magnet is being presented. The experiment should be done with extreme caution, as liquid oxygen reacts violently with organic matters.

Rare earth gas laser

DOEpatents

Krupke, W.F.

1975-10-31

A high energy gas laser with light output in the infrared or visible region of the spectrum is described. Laser action is obtained by generating vapors of rare earth halides, particularly neodymium iodide or, to a lesser extent, neodymium bromide, and disposing the rare earth vapor medium in a resonant cavity at elevated temperatures; e.g., approximately 1200/sup 0/ to 1400/sup 0/K. A particularly preferred gaseous medium is one involving a complex of aluminum chloride and neodymium chloride, which exhibits tremendously enhanced vapor pressure compared to the rare earth halides per se, and provides comparable increases in stored energy densities.

Treatment of vitreous floaters with neodymium YAG laser.

PubMed Central

Tsai, W F; Chen, Y C; Su, C Y

1993-01-01

Fifteen cases of vitreous floaters with serious psychological reactions have been collected. By using a direct ophthalmoscope, causal vitreous opacities were detected. The opacities were photodisrupted with neodymium YAG laser, using energy levels of 5 to 7.1 mJ and total energy 71 to 742.0 mJ. Symptoms completely disappeared immediately after treatment in all 15 cases. There were no intraoperative or postoperative complications noted during a follow up period of at least 1 year. To our knowledge, the use of neodymium YAG laser to treat vitreous floaters has not been previously described. Our initial experience indicates that the treatment is simple, safe, and effective. Images PMID:8025044

Structural, electronic and thermal properties of super hard ternary boride, WAlB

NASA Astrophysics Data System (ADS)

Rajpoot, Priyanka; Rastogi, Anugya; Verma, U. P.

2018-04-01

A first principle study of the structural, electronic and thermal properties of Tungsten Aluminum Boride (WAlB) using full-potential linearized augmented plane wave (FP-LAPW) in the frame work of density function theory (DFT) have been calculated. The calculated equilibrium structural parameters are in excellent agreement with available experimental results. The calculated electronic band structure reveals that WAlB is metallic in nature. The quasi-harmonic Debye model is applied to study of the temperature and pressure effect on volume, Debye temperature, thermal expansion coefficient and specific heat at constant volume and constant pressure. To the best of our knowledge theoretical investigation of these properties of WAlB is reported for the first time.

Infiltration processing of boron carbide-, boron-, and boride-reactive metal cermets

DOEpatents

Halverson, Danny C.; Landingham, Richard L.

1988-01-01

A chemical pretreatment method is used to produce boron carbide-, boron-, and boride-reactive metal composites by an infiltration process. The boron carbide or other starting constituents, in powder form, are immersed in various alcohols, or other chemical agents, to change the surface chemistry of the starting constituents. The chemically treated starting constituents are consolidated into a porous ceramic precursor which is then infiltrated by molten aluminum or other metal by heating to wetting conditions. Chemical treatment of the starting constituents allows infiltration to full density. The infiltrated precursor is further heat treated to produce a tailorable microstructure. The process at low cost produces composites with improved characteristics, including increased toughness, strength.

Demonstrating and Measuring Relative Molar Magnetic Susceptibility Using a Neodymium Magnet

ERIC Educational Resources Information Center

Malerich, Charles; Ruff, Patricia K.; Bird, Aubrey

2004-01-01

An easy-to-see method for demonstrating and measuring the magnetic force between paramagnetic substance and a rare earth magnet is presented. The readily available trapezoid-shaped neodymium magnet and a low cost, easy-to-set-up, portable apparatus are used in the experiments.

Complexation of Nd(III) with tetraborate ion and its effect on actinide (III) solubility in WIPP brine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borkowski, Marian; Richmann, Michael K; Reed, Donald T

2010-01-01

The potential importance of tetraborate complexation on lanthanide(III) and actinide(III) solubility is recognized in the literature but a systematic study of f-element complexation has not been performed. In neodymium solubility studies in WIPP brines, the carbonate complexation effect is not observed since tetraborate ions form a moderately strong complex with neodymium(III). The existence of these tetraborate complexes was established for low and high ionic strength solutions. Changes in neodymium(III) concentrations in undersaturation experiments were used to determine the neodymium with tetraborate stability constants as a function of NaCl ionic strength. As very low Nd(III) concentrations have to be measured, itmore » was necessary to use an extraction pre-concentration step combined with ICP-MS analysis to extend the detection limit by a factor of 50. The determined Nd(III) with borate stability constants at infinite dilution and 25 C are equal to log {beta}{sub 1} = 4.55 {+-} 0.06 using the SIT approach, equal to log {beta}{sub 1} = 4.99 {+-} 0.30 using the Pitzer approach, with an apparent log {beta}{sub 1} = 4.06 {+-} 0.15 (in molal units) at I = 5.6 m NaCl. Pitzer ion-interaction parameters for neodymium with tetraborate and SIT interaction coefficients were also determined and reported.« less

Material flow analysis of NdFeB magnets for Denmark: a comprehensive waste flow sampling and analysis approach.

PubMed

Habib, Komal; Schibye, Peter Klausen; Vestbø, Andreas Peter; Dall, Ole; Wenzel, Henrik

2014-10-21

Neodymium-iron-boron (NdFeB) magnets have become highly desirable for modern hi-tech applications. These magnets, in general, contain two key rare earth elements (REEs), i.e., neodymium (Nd) and dysprosium (Dy), which are responsible for the very high strength of these magnets, allowing for considerable size and weight reduction in modern applications. This study aims to explore the current and future potential of a secondary supply of neodymium and dysprosium from recycling of NdFeB magnets. For this purpose, material flow analysis (MFA) has been carried out to perform the detailed mapping of stocks and flows of NdFeB magnets in Denmark. A novel element of this study is the value added to the traditionally practiced MFAs at national and/or global levels by complementing them with a comprehensive sampling and elemental analysis of NdFeB magnets, taken out from a sample of 157 different products representing 18 various product types. The results show that the current amount of neodymium and dysprosium in NdFeB magnets present in the Danish waste stream is only 3 and 0.2 Mg, respectively. However, this number is estimated to increase to 175 Mg of neodymium and 11.4 Mg of dysprosium by 2035. Nevertheless, efficient recovery of these elements from a very diverse electronic waste stream remains a logistic and economic challenge.

UV and fluorescence spectral changes induced by neodymium binding of N,N'-ethylenebis[2-(o-hydroxyphenolic)glycine] and N,N'-di(2-hydroxybenzyl)ethylenediamine-N,N' diacetic acid.

PubMed

Wang, Zhijun; Yang, Binsheng

2006-11-01

In 0.01 M 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (Hepes), pH 7.4 and room temperature, the binding of neodymium to N,N'-ethylenebis[2-(o-hydroxyphenolic)glycine] (EHPG), or N,N'-di(2-hydroxybenzyl)ethylenediamine-N,N' diacetic acid (HBED) had been studied from 210 to 330 nm by means of difference UV spectra. Two peaks at 240 and 292 nm appear in difference UV spectra after neodymium binding to EHPG or HBED. The 1:1 stable complex can be confirmed from spectral titration curves. The molar extinction coefficient of Nd-EHPG and Nd-HBED complexes are Deltaepsilon(Nd-EHPG)=(12.93+/-0.21) x 10(3)cm(-1)M(-1), Deltaepsilon(Nd-HBED)=(14.45+/-0.51) x 10(5)cm(-1)M(-1) at 240 nm, respectively. Using EDTA as a competitor, the conditional equilibrium constants of the complexes are logK(Nd-EHPG)=11.89+/-0.09 and logK(Nd-HBED)=12.19+/-0.15, respectively. At the same conditions, fluorescence measurements show that neodymium binding to EHPG leads to a quenching of the fluorescence of EHPG at near 310 nm. However, there is no obvious fluorescence change of HBED at 318 nm with the binding of neodymium to HBED.

The Quantitative Significance of Nondestructive Evaluation of Graphite and Ceramic Materials.

DTIC Science & Technology

NONDESTRUCTIVE TESTING), (* GRAPHITE , (*BORIDES, NONDESTRUCTIVE TESTING), (*REFRACTORY MATERIALS, NONDESTRUCTIVE TESTING), DEFECTS(MATERIALS), TENSILE PROPERTIES, RADIOGRAPHY, ULTRASONIC PROPERTIES, DENSITY.

High-Temperature Syntheses of New, Thermally-Stable Chemical Compounds.

DTIC Science & Technology

SYNTHESIS(CHEMISTRY), HEAT RESISTANT PLASTICS, NITRILES, FLUORINE COMPOUNDS, COMPLEX COMPOUNDS, NITROGEN, SULFIDES, ORGANOMETALLIC COMPOUNDS, ORGANOBORANES, BORIDES, SPINEL, CARBIDES, NITRIDES, SILICIDES .

X-ray emission from a plasma mirror of a neodymium glass laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalal, M.; Pina, L.; Vrbova, M.

1984-11-01

An investigation was made of the optical and x-ray characteristics of the radiation emitted by a plasma mirror in a neodymium glass laser. The optical reflection coefficient of the mirror was found to be nonlinear and the plasma temperature was about 300 eV.

B Layers and Adhesion on Armco Iron Substrate

NASA Astrophysics Data System (ADS)

Elias-Espinosa, M.; Ortiz-Domínguez, M.; Keddam, M.; Flores-Rentería, M. A.; Damián-Mejía, O.; Zuno-Silva, J.; Hernández-Ávila, J.; Cardoso-Legorreta, E.; Arenas-Flores, A.

2014-08-01

In this work, a kinetic model was suggested to evaluate the boron diffusion coefficient in the Fe2B layers grown on the Armco iron substrate by the powder-pack boriding. This thermochemical treatment was carried out in the temperature range of 1123-1273 K for treatment times ranging from 2 to 8 h. The boron diffusion coefficient in the Fe2B layers was estimated by solving the mass balance equation at the (Fe2B/substrate) interface with an inclusion of boride incubation time. To validate the present model, the simulated value of Fe2B layer thickness was compared with the experimental value obtained at 1253 K for a treatment time of 5 h. The morphology of Fe2B layers was observed by SEM and optical microscopy. Metallographic studies showed that the boride layer has a saw-tooth morphology in all the samples. The layer thickness measurements were done with the help of MSQ PLUS software. The Fe2B phase was identified by x-ray diffraction method. Finally, the adherence of Fe2B layers on the Armco iron substrate was qualitatively evaluated by using the Daimler-Benz Rockwell-C indentation technique. In addition, the estimated value of boron activation energy was compared to the literature data.

A Simple, General Synthetic Route toward Nanoscale Transition Metal Borides.

PubMed

Jothi, Palani R; Yubuta, Kunio; Fokwa, Boniface P T

2018-04-01

Most nanomaterials, such as transition metal carbides, phosphides, nitrides, chalcogenides, etc., have been extensively studied for their various properties in recent years. The similarly attractive transition metal borides, on the contrary, have seen little interest from the materials science community, mainly because nanomaterials are notoriously difficult to synthesize. Herein, a simple, general synthetic method toward crystalline transition metal boride nanomaterials is proposed. This new method takes advantage of the redox chemistry of Sn/SnCl 2 , the volatility and recrystallization of SnCl 2 at the synthesis conditions, as well as the immiscibility of tin with boron, to produce crystalline phases of 3d, 4d, and 5d transition metal nanoborides with different morphologies (nanorods, nanosheets, nanoprisms, nanoplates, nanoparticles, etc.). Importantly, this method allows flexibility in the choice of the transition metal, as well as the ability to target several compositions within the same binary phase diagram (e.g., Mo 2 B, α-MoB, MoB 2 , Mo 2 B 4 ). The simplicity and wide applicability of the method should enable the fulfillment of the great potential of this understudied class of materials, which show a variety of excellent chemical, electrochemical, and physical properties at the microscale. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Corrosion and wear behaviors of boronized AISI 316L stainless steel

NASA Astrophysics Data System (ADS)

Kayali, Yusuf; Büyüksaǧiş, Aysel; Yalçin, Yılmaz

2013-09-01

In this study, the effects of a boronizing treatment on the corrosion and wear behaviors of AISI 316L austenitic stainless steel (AISI 316L) were examined. The corrosion behavior of the boronized samples was studied via electrochemical methods in a simulation body fluid (SBF) and the wear behavior was examined using the ball-on-disk wear method. It was observed that the boride layer that formed on the AISI 316L surface had a flat and smooth morphology. Furthermore, X-ray diffraction analyses show that the boride layer contained FeB, Fe2B, CrB, Cr2B, NiB, and Ni2B phases. Boride layer thickness increased with an increasing boronizing temperature and time. The boronizing treatment also increased the surface hardness of the AISI 316L. Although there was no positive effect of the coating on the corrosion resistance in the SBF medium. Furthermore, a decrease in the friction coefficient was recorded for the boronized AISI 316L. As the boronizing temperature increased, the wear rate decreased in both dry and wet mediums. As a result, the boronizing treatment contributed positively to the wear resistance by increasing the surface hardness and by decreasing the friction coefficient of the AISI 316L.

Design of cemented tungsten carbide and boride-containing shields for a fusion power plant

NASA Astrophysics Data System (ADS)

Windsor, C. G.; Marshall, J. M.; Morgan, J. G.; Fair, J.; Smith, G. D. W.; Rajczyk-Wryk, A.; Tarragó, J. M.

2018-07-01

Results are reported on cemented tungsten carbide (cWC) and boride-containing composite materials for the task of shielding the centre column of a superconducting tokamak power plant. The shield is based on five concentric annular shells consisting of cWC and water layers of which the innermost cWC shield can be replaced with boride composites. Sample materials have been fabricated changing the parameters of porosity P, binder alloy fraction f binder and boron weight fraction f boron. For the fabricated materials, and other hypothetical samples with chosen parameters, Monte Carlo studies are made of: (i) the power deposition into the superconducting core, (ii) the fast neutron and gamma fluxes and (iii) the attenuation coefficients through the shield for the deposited power and neutron and gamma fluxes. It is shown that conventional Co-based cWC binder alloy can be replaced with a Fe–Cr alloy (92 wt.% Fe, 8 wt.% Cr), which has lower activation than cobalt with minor changes in shield performance. Boride-based composite materials have been prepared and shown to give a significant reduction in power deposition and flux, when placed close to the superconducting core. A typical shield of cemented tungsten carbide with 10 wt.% of Fe–8Cr binder and 0.1% porosity has a power reduction half-length of 0.06 m. It is shown that the power deposition increases by 4.3% for every 1% additional porosity, and 1.7% for every 1 wt.% additional binder. Power deposition decreased by 26% for an initial 1 wt.% boron addition, but further increases in f boron showed only a marginal decrease. The dependences of power deposited in the core, the maximum neutron and gamma fluxes on the core surface, and the half attenuation distances through the shield have been fitted to within a fractional percentage error by analytic functions of the porosity, metallic binder alloy and boron weight fractions.

Etude des mecanismes de formation des microstructures lors du brasage isotherme de superalliages a base de nickel

NASA Astrophysics Data System (ADS)

Ruiz-Vargas, Jose

This thesis reports theoretical and experimental investigations carried out to understand the mechanisms of microstructure formation during isothermal brazing, produced by brazing Inconel 625 and MC2 nickel-based superalloys with filler metal BNi-2. Firstly, studies were made on pure Ni to interpret microstructure's formation with simplified alloy chemistry. Microstructure formation have been studied when varying time at constant temperature (isothermal kinetics), but also when varying temperature for constant hold time (isochronal kinetics). The chemical composition and crystallography of the present phases have been identified, with the following results : (i) the fraction of dissolved base metal has been found proportional to the initial thickness of the brazing alloy, so that the composition of the liquid remains homogeneous with a precise initial equilibrium composition during the whole brazing process, (ii) the melting of the joint occurs in two steps : at lower temperature, it involves only partially melting, and boron diffusion in pure Ni leads to the precipitation of fine Ni3B borides at the interface ; in a second stage, at higher temperature, melting is complete and thermodynamic equilibrium requires significant dissolution of nickel, which also involves the dissolution of part of borides already formed. Secondly, nickel plating technique was used on Inconel 625 nickel-based superalloy. A thin layer of Ni with varying thickness, has been electrodeposited to observe the gradual dissolution of Inconel and microstructural features formation due to the presence of superalloy alloying elements. It has been observed that the nickel coating does not prevent precipitation in the base metal as boron diffuse rapidly through the coating width. In the intermediate nickel plating width, fragile precipitates of nickel borides have been observed, because the contribution of Inconel alloying elements to the melt was very limited. In absence of nickel plating on the superalloy, the formation of Nb and Cr-Mo borides phase has been observed. Efforts have been made to evaluate the accuracy of Boron measurement by energy dispersion X-ray spectroscopy (EDS) in the MC2 superalloy and BNi-2 filler metal. The most accurate method to quantify Boron using EDS is by composition difference. A precision of 5 at.% has been reached when using optimized data acquisition and post processing schemes. Ultimately, Electron Backscatter Diffraction (EBSD) combined with localized EDS analysis has been proven invaluable in conclusively identifying micrometer sized boride precipitates ; thus further improving the characterization of brazed Ni-based superalloys.

Plasma enhanced chemical vapor deposition of metalboride interfacial layers as diffusion barriers for nanostructured diamond growth on cobalt containing alloys CoCrMo and WC-Co

NASA Astrophysics Data System (ADS)

Johnston, Jamin M.

This work is a compilation of theory, finite element modeling and experimental research related to the use of microwave plasma enhanced chemical vapor deposition (MPECVD) of diborane to create metal-boride surface coatings on CoCrMo and WC-Co, including the subsequent growth of nanostructured diamond (NSD). Motivation for this research stems from the need for wear resistant coatings on industrial materials, which require improved wear resistance and product lifetime to remain competitive and satisfy growing demand. Nanostructured diamond coatings are a promising solution to material wear but cannot be directly applied to cobalt containing substrates due to graphite nucleation. Unfortunately, conventional pre-treatment methods, such as acid etching, render the substrate too brittle. Thus, the use of boron in a MPECVD process is explored to create robust interlayers which inhibit carbon-cobalt interaction. Furthermore, modeling of the MPECVD process, through the COMSOL MultiphysicsRTM platform, is performed to provide insight into plasma-surface interactions using the simulation of a real-world apparatus. Experimental investigation of MPECVD boriding and NSD deposition was conducted at surface temperatures from 700 to 1100 °C. Several well-adhered metal-boride surface layers were formed: consisting of CoB, CrB, WCoB, CoB and/or W2CoB2. Many of the interlayers were shown to be effective diffusion barriers against elemental cobalt for improving nucleation and adhesion of NSD coatings; diamond on W2CoB2 was well adhered. However, predominantly WCoB and CoB phase interlayers suffered from diamond film delamination. Metal-boride and NSD surfaces were evaluated using glancing-angle x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), cross-sectional scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), micro-Raman spectroscopy, nanoindentation, scratch testing and epoxy pull testing. COMSOL MultiphysicsRTM was used to construct a representation of the MPECVD chamber. Relevant material properties, boundary conditions and adjustable parameters were applied to match the actual experimental set-up. Despite approximations, simulations for the surface temperature and surface accumulation matched well with experimental data. The combination of data from CoCrMo, WC-Co and modeling of the MPECVD process confirms that the use of boron to create metal-boride interlayers is applicable for subsequent nanostructured diamond coatings and that the surface temperature and deposition thickness can be predicted using finite element modeling.

Deposition and characterization of aluminum magnesium boride thin film coatings

NASA Astrophysics Data System (ADS)

Tian, Yun

Boron-rich borides are a special group of materials possessing complex structures typically comprised of B12 icosahedra. All of the boron-rich borides sharing this common structural unit exhibit a variety of exceptional physical and electrical properties. In this work, a new ternary boride compound AlMgB14, which has been extensively studied in bulk form due to its novel mechanical properties, was fabricated into thin film coatings by pulsed laser deposition (PLD) technology. The effect of processing conditions (laser operating modes, vacuum level, substrate temperature, and postannealing, etc.) on the composition, microstructure evolution, chemical bonding, and surface morphology of AlMgB14 thin film coatings has been investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectrometry; the mechanical, electrical, and optical properties of AlMgB14 thin films have been characterized by nanoindentation, four-point probe, van der Pauw Hall measurement, activation energy measurement, and UV-VIS-NIR spectrophotometer. Experimental results show that AlMgB14 films deposited in the temperature range of 300 K - 873 K are amorphous. Depositions under a low vacuum level (5 x 10-5 Torr) can introduce a significant amount of C and O impurities into AlMgB14 films and lead to a complex oxide glass structure. Orthorhombic AlMgB14 phase cannot be obtained by subsequent high temperature annealing. By contrast, the orthorhombic AlMgB 14 crystal structure can be attained via high temperature-annealing of AlMgB14 films deposited under a high vacuum level (< 3 x 10-6 Torr), accompanied by strong texture formation. Low vacuum level-as deposited AlMgB14 films have low hardness (10 GPa), but high vacuum level-as deposited AlMgB14 films exhibit an extremely high hardness (45 GPa - 51 GPa), and the higher deposition temperature results in still higher hardness. Furthermore, a very low friction coefficient (0.04 - 0.05) has been observed for high vacuum level-as deposited AlMgB14 films, which could be ascribed to the in situ formation of a surface self-lubricating layer. Unlike most boron-rich boride films, high vacuum level-as deposited AlMgB14 films also possess a low n-type electrical resistivity, which is a consequence of high carrier concentration and moderate carrier mobility. The operative electrical transport mechanism and doping behavior for high vacuum level-as deposited AlMgB14 films are discussed in detail in this thesis.

Solar nebula heterogeneity in p-process samarium and neodymium isotopes.

PubMed

Andreasen, Rasmus; Sharma, Mukul

2006-11-03

Bulk carbonaceous chondrites display a deficit of approximately 100 parts per million (ppm) in 144Sm with respect to other meteorites and terrestrial standards, leading to a decrease in their 142Nd/144Nd ratios by approximately 11 ppm. The data require that samarium and neodymium isotopes produced by the p process associated with photodisintegration reactions in supernovae were heterogeneously distributed in the solar nebula. Other samarium and neodymium isotopes produced by rapid neutron capture (r process) in supernovae and by slow neutron capture (s process) in red giants were homogeneously distributed. The supernovae sources supplying the p- and r-process nuclides to the solar nebula were thus disconnected or only weakly connected.

Synthesis of neodymium hydroxide nanotubes and nanorods by soft chemical process.

PubMed

Shi, Weidong; Yu, Jiangbo; Wang, Haishui; Yang, Jianhui; Zhang, Hongjie

2006-08-01

A facile soft chemical approach using cetyltrimethylammonium bromide (CTAB) as template is successfully designed for synthesis of neodymium hydroxide nanotubes. These nanotubes have an average outer diameter around 20 nm, inner diameter around 2 nm, and length ranging from 100 to 120 nm, high BET surface area of 495.71 m(2) g(-1). We also find that neodymium hydroxide nanorods would be obtained when CTAB absented in reaction system. The Nd(OH)3 nanorods might act as precursors that are converted into Nd2O3 nanorods through dehydration at 550 degrees C. The nanorods could exhibit upconversion emission characteristic under excitation of 591 nm at room temperature.

10 CFR Appendix L to Part 110 - Illustrative List of Byproduct Materials Under NRC Export/Import Licensing Authority a

Code of Federal Regulations, 2011 CFR

2011-01-01

...) Neodymium 147 (Nd 147) Neodymium 149 (Nd 149) Neptunium 235 (Np 235) Neptunium 237 (Np 237) Nickel 59 (Ni 59) Nickel 63 (Ni 63) Nickel 65 (Ni 65) Niobium 93m (Nb 93m) Niobium 94 (Nb 94) Niobium 95 (Nb 95) Niobium 97...

Direct synthesis of magnesium borohydride

DOEpatents

Ronnebro, Ewa Carin Ellinor [Kennewick, WA; Severa, Godwin [Honolulu, HI; Jensen, Craig M [Kailua, HI

2012-04-03

A method is disclosed for directly preparing an alkaline earth metal borohydride, i.e. Mg(BH.sub.4).sub.2, from the alkaline earth metal boride MgB.sub.2 by hydrogenating the MgB.sub.2 at an elevated temperature and pressure. The boride may also be doped with small amounts of a metal chloride catalyst such as TiCl.sub.3 and/or NiCl.sub.2. The process provides for charging MgB.sub.2 with high pressure hydrogen above at least 70 MPa while simultaneously heating the material to about 350.degree. C. to about 400.degree. C. The method is relatively simple and inexpensive and provides a reversible hydride compound having a hydrogen capacity of at least 11 wt %.

The low-lying quartet electronic states of group 14 diatomic borides XB (X = C, Si, Ge, Sn, Pb)

NASA Astrophysics Data System (ADS)

Pontes, Marcelo A. P.; de Oliveira, Marcos H.; Fernandes, Gabriel F. S.; Da Motta Neto, Joaquim D.; Ferrão, Luiz F. A.; Machado, Francisco B. C.

2018-04-01

The present work focuses in the characterization of the low-lying quartet electronic and spin-orbit states of diatomic borides XB, in which X is an element of group 14 (C, Si, Ge, Sn, PB). The wavefunction was obtained at the CASSCF/MRCI level with a quintuple-ζ quality basis set. Scalar relativistic effects were also taken into account. A systematic and comparative analysis of the spectroscopic properties for the title molecular series was carried out, showing that the (1)4Π→X4Σ- transition band is expected to be measurable by emission spectroscopy to the GeB, SnB and PbB molecules, as already observed for the lighter CB and SiB species.

A molten salt process for producing neodymium and neodymium-iron alloys

NASA Astrophysics Data System (ADS)

Sharma, Ram A.; Seefurth, Randall N.

1989-12-01

The production of low-cost neodymium metal in a stirred tank reactor by the reduction of Nd2O3 with sodium in the presence of CaCl2-KCl-NaCl melts by the overall reaction Nd2O3+3CaCl2+6Na→2Nd+3CaO+6NaCl at ˜750 °C is described. The metal produced is recovered from the salt medium by dissolving it in a Nd-Zn or Nd-Fe alloy pool. In the case of Nd-Zn alloy pools, product yields (percentages of theoretical neodymium produced) in excess of 94 pct are obtained when using salt ratios, i.e., the amounts of salt per gram of neodymium produced, ≥3.5 and excess reductant ≥10 pct. The alloy produced is of high quality, and following vacuum distillation of the zinc, can be used in producing General Motors’ MAGNEQUENCH alloy for permanent magnets. In the case of Nd-Fe pools, the yield is also ˜95 pct with a salt ratio as low as 3.5. The yield is found to depend on the salt composition and salt ratio, and to decrease at salt ratios below 3.25. Stirrer position has little effect on yield, while increasing the temperature and placing fins in the reactor increase the yield. The Nd-Fe alloy produced is of as good quality as that produced using Ca reductant and is suitable for direct use in preparing the MAGNEQUENCH alloy.

The impact of sedimentary coatings on the diagenetic Nd flux

NASA Astrophysics Data System (ADS)

Abbott, April N.; Haley, Brian A.; McManus, James

2016-09-01

Because ocean circulation impacts global heat transport, understanding the relationship between deep ocean circulation and climate is important for predicting the ocean's role in climate change. A common approach to reconstruct ocean circulation patterns employs the neodymium isotope compositions of authigenic phases recovered from marine sediments. In this approach, mild chemical extractions of these phases is thought to yield information regarding the εNd of the bottom waters that are in contact with the underlying sediment package. However, recent pore fluid studies present evidence for neodymium cycling within the upper portions of the marine sediment package that drives a significant benthic flux of neodymium to the ocean. This internal sedimentary cycling has the potential to obfuscate any relationship between the neodymium signature recovered from the authigenic coating and the overlying neodymium signature of the seawater. For this manuscript, we present sedimentary leach results from three sites on the Oregon margin in the northeast Pacific Ocean. Our goal is to examine the potential mechanisms controlling the exchange of Nd between the sedimentary package and the overlying water column, as well as the relationship between the εNd composition of authigenic sedimentary coatings and that of the pore fluid. In our comparison of the neodymium concentrations and isotope compositions from the total sediment, sediment leachates, and pore fluid we find that the leachable components account for about half of the total solid-phase Nd, therefore representing a significant reservoir of reactive Nd within the sediment package. Based on these and other data, we propose that sediment diagenesis determines the εNd of the pore fluid, which in turn controls the εNd of the bottom water. Consistent with this notion, despite having 1 to 2 orders of magnitude greater Nd concentration than the bottom water, the pore fluid is still <0.001% of the total Nd reservoir in the upper sediment column. Therefore, the pore fluid reservoir is too small to maintain a unique signature, and instead must be controlled by the larger reservoir of Nd in the reactive coatings. In addition, to achieve mass balance, we find it necessary to invoke a cryptic radiogenic (εNd of +10) trace mineral source of neodymium within the upper sediment column at our sites. When present, this cryptic trace metal results in more radiogenic pore fluid.

Neodymium-doped nanoparticles for infrared fluorescence bioimaging: The role of the host

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosal, Blanca del; Pérez-Delgado, Alberto; Rocha, Ueslen

2015-10-14

The spectroscopic properties of different infrared-emitting neodymium-doped nanoparticles (LaF{sub 3}:Nd{sup 3+}, SrF{sub 2}:Nd{sup 3+}, NaGdF{sub 4}: Nd{sup 3+}, NaYF{sub 4}: Nd{sup 3+}, KYF{sub 4}: Nd{sup 3+}, GdVO{sub 4}: Nd{sup 3+}, and Nd:YAG) have been systematically analyzed. A comparison of the spectral shapes of both emission and absorption spectra is presented, from which the relevant role played by the host matrix is evidenced. The lack of a “universal” optimum system for infrared bioimaging is discussed, as the specific bioimaging application and the experimental setup for infrared imaging determine the neodymium-doped nanoparticle to be preferentially used in each case.

Microstructural characterization of Ni-based self-fluxing alloy after selective surface-engineering using diode laser

NASA Astrophysics Data System (ADS)

Chun, Eun-Joon; Park, Changkyoo; Nishikawa, Hiroshi; Kim, Min-Su

2018-06-01

The microstructural characterization of thermal-sprayed Ni-based self-fluxing alloy (Metco-16C®) after laser-assisted homogenization treatment was performed. To this end, a high-power diode laser system was used. This supported the real-time control of the target homogenization temperature at the substrate surface. Non-homogeneities of the macrosegregation of certain elements (C and Cu) and the local concentration of Cr-based carbides and borides in certain regions in the as-sprayed state could be enhanced with the application of homogenization. After homogenization at 1423 K, the hardness of the thermal-sprayed layer was found to have increased by 1280 HV from the as-sprayed state (750 HV). At this homogenization temperature, the microstructure of the thermal-sprayed layer consisted of a lamellar structuring of the matrix phase (austenite and Ni3Si) with fine (<5 μm) carbides and borides (the rod-like phase of Cr5B3, the lumpy phase of M23C6, and the extra-fine phase of M7C3). Despite the formation of several kinds of carbides and borides during homogenization at 1473 K, the lowest hardness level was found to be less than that of the as-sprayed state, because of the liquid-state homogenization treatment without formation of lamellar structuring between austenite and Ni3Si.

Quantitative SIMS depth profiling of diffusion barrier gate-oxynitride structures in TFT-LCDs.

PubMed

Dreer, Sabine; Wilhartitz, Peter; Piplits, Kurt; Mayerhofer, Karl; Foisner, Johann; Hutter, Herbert

2004-06-01

Gate oxynitride structures of TFT-LCDs were investigated by SIMS, and successful solutions are demonstrated to overcome difficulties arising due to the charging effects of the multilayer systems, the matrix effect of the method, and the small pattern sizes of the samples. Because of the excellent reproducibility achieved by applying exponential relative sensitivity functions for quantitative analysis, minor differences in the barrier gate-oxynitride composition deposited on molybdenum capped aluminium-neodymium metallisation electrodes were determined between the centre and the edge of the TFT-LCD substrates. No differences were found for molybdenum-tungsten metallisations. Furthermore, at the edge of the glass substrates, aluminium, neodymium, and molybdenum SIMS depth profiles show an exponential trend. With TEM micrographs an inhomogeneous thickness of the molybdenum capping is revealed as the source of this effect, which influences the electrical behaviour of the device. The production process was improved after these results and the aging behaviour of TFT-LCDs was investigated in order to explain the change in control voltage occurring during the lifetime of the displays. SIMS and TEM show an enrichment of neodymium at the interface to the molybdenum layer, confirming good diffusion protection of the molybdenum barrier during accelerated aging. The reason for the shift of the control voltage was finally located by semi-quantitative depth profiling of the sodium diffusion originating from the glass substrate. Molybdenum-tungsten was a much better buffer for the highly-mobile charge carriers than aluminium-neodymium. Best results were achieved with PVD silicon oxynitride as diffusion barrier and gate insulator deposited on aluminium-neodymium metallisation layers.

NASA research on refractory compounds.

NASA Technical Reports Server (NTRS)

Gangler, J. J.

1971-01-01

The behavior and properties of the refractory carbides, nitrides, and borides are being investigated by NASA as part of its research aimed at developing superior heat resistant materials for aerospace applications. Studies of the zirconium-carbon-oxygen system show that zirconium oxycarbides of different compositions and lattice parameters can be formed between 1500 C and 1900 C and are stable below 1500 C. More applied studies show that hot working generally improves the microstructure and therefore the strength of TiC and NbC. Sintering studies on UN indicate that very high densities can be achieved. Hot pressing of cermets of HfN and HfC produces good mechanical properties for high temperature bearing applications. Attempts to improve the impact resistance of boride composites by the addition of a nickel or carbon yarn were not overly successful.

Ceramic fibers from Si-B-C polymer precursors

NASA Technical Reports Server (NTRS)

Riccitiello, S. R.; Hsu, M. S.; Chen, T. S.

1993-01-01

Non-oxide ceramics such as silicon carbide (SiC), silicon nitride (Si3N4), and silicon borides (SiB4, SiB6) have thermal stability, oxidation resistance, hardness, and varied electrical properties. All these materials can be prepared in a fiber form from a suitable polymer precursor. The above mentioned fibers, when tested over a temperature range from 25 to 1400 C, experience degradation at elevated temperatures. Past work in ceramic materials has shown that the strength of ceramics containing both carbides and borides is sustained at elevated temperatures, with minimum oxidation. The work presented here describes the formation of ceramic fibers containing both elements, boron and silicon, prepared via the polymer precursor route previously reported by the authors, and discusses the fiber mechanical properties that are retained over the temperature range studied.

Low-cost industrially available molybdenum boride and carbide as "platinum-like" catalysts for the hydrogen evolution reaction in biphasic liquid systems.

PubMed

Scanlon, Micheál D; Bian, Xiaojun; Vrubel, Heron; Amstutz, Véronique; Schenk, Kurt; Hu, Xile; Liu, BaoHong; Girault, Hubert H

2013-02-28

Rarely reported low-cost molybdenum boride and carbide microparticles, both of which are available in abundant quantities due to their widespread use in industry, adsorb at aqueous acid-1,2-dichloroethane interfaces and efficiently catalyse the hydrogen evolution reaction in the presence of the organic electron donor - decamethylferrocene. Kinetic studies monitoring biphasic reactions by UV/vis spectroscopy, and further evidence provided by gas chromatography, highlight (a) their superior rates of catalysis relative to other industrially significant transition metal carbides and silicides, as well as a main group refractory compound, and (b) their highly comparable rates of catalysis to Pt microparticles of similar dimensions. Insight into the catalytic processes occurring for each adsorbed microparticle was obtained by voltammetry at the liquid-liquid interface.

Ternary ceramic thermal spraying powder and method of manufacturing thermal sprayed coating using said powder

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vogli, Evelina; Sherman, Andrew J.; Glasgow, Curtis P.

The invention describes a method for producing ternary and binary ceramic powders and their thermal spraying capable of manufacturing thermal sprayed coatings with superior properties. Powder contain at least 30% by weight ternary ceramic, at least 20% by weight binary molybdenum borides, at least one of the binary borides of Cr, Fe, Ni, W and Co and a maximum of 10% by weight of nano and submicro-sized boron nitride. The primary crystal phase of the manufactured thermal sprayed coatings from these powders is a ternary ceramic, while the secondary phases are binary ceramics. The coatings have extremely high resistance againstmore » corrosion of molten metal, extremely thermal shock resistance and superior tribological properties at low and at high temperatures.« less

Design of Wear-Resistant Austenitic Steels for Selective Laser Melting

NASA Astrophysics Data System (ADS)

Lemke, J. N.; Casati, R.; Lecis, N.; Andrianopoli, C.; Varone, A.; Montanari, R.; Vedani, M.

2018-03-01

Type 316L stainless steel feedstock powder was modified by alloying with powders containing carbide/boride-forming elements to create improved wear-resistant austenitic alloys that can be readily processed by Selective Laser Melting. Fe-based alloys with high C, B, V, and Nb contents were thus produced, resulting in a microstructure that consisted of austenitic grains and a significant amount of hard carbides and borides. Heat treatments were performed to modify the carbide distribution and morphology. Optimal hard-phase spheroidization was achieved by annealing the proposed alloys at 1150 °C for 1 hour followed by water quenching. The total increase in hardness of samples containing 20 pct of C/B-rich alloy powder was of 82.7 pct while the wear resistance could be increased by a factor of 6.

Nanostructured silicon ferromagnet collected by a permanent neodymium magnet.

PubMed

Okuno, Takahisa; Thürmer, Stephan; Kanoh, Hirofumi

2017-11-30

Nanostructured silicon (N-Si) was prepared by anodic electroetching of p-type silicon wafers. The obtained magnetic particles were separated by a permanent neodymium magnet as a magnetic nanostructured silicon (mN-Si). The N-Si and mN-Si exhibited different magnetic properties: the N-Si exhibited ferromagnetic-like behaviour, whereas the mN-Si exhibited superparamagnetic-like behaviour.

Neodymium:YAG laser cutting of intraocular lens haptics.

PubMed

Gorn, R A; Steinert, R F

1985-11-01

Neodymium:YAG laser cutting of polymethylmethacrylate and polypropylene anterior chamber and posterior chamber intraocular lens haptics was studied in terms of ease of transection and physical structure of the cut areas as seen by scanning electron microscopy. A marked difference was discovered, with the polymethylmethacrylate cutting easily along transverse planes, whereas the polypropylene resisted cutting along longitudinal fibers. Clinical guidelines are presented.

Electronic Structure Properties and a Bonding Model of Thermoelectric Half-Heusler and Boride Phases

NASA Astrophysics Data System (ADS)

Simonson, Jack William

Half-Heusler alloys MNiSn and MCoSb (M = Ti, Zr, Hf) and layered boride intermetallics with structure types YCrB4 and Er 3CrB7 were designed, synthesized, and characterized. The thermoelectric properties of these two classes of alloys were measured from room temperature to 1100 K with the intent of indirectly studying their electronic structure properties and gauging not only their suitability but that of related alloys for high temperature thermoelectric power generation. In the case of the half-Heusler alloys, transition metals were substituted to both the M and Ni/Co sites to study the resultant modifications of the d-orbital-rich portion of the electronic structure near the Fermi energy. This modification and subsequent pinning of the Fermi energy within the gap is discussed herein in terms of first principles electronic structure calculations from the literature. In the half-Heusler alloys, it was found that substitution of transition metals invariably led to a decrease in the thermopower, while the resistivity typically maintained its semiconducting trend. On the other hand, Sn doping in MCoSb type alloys -- a dopant that has been known for some time to be efficient -- was shown to result in high ZT at temperatures in excess of 1000 K. Moreover, the band gaps of the transition metal-doped alloys measured in this work offer insight into the discrepancy between the predicted and measured band gaps in the undoped parent compositions. In the case of the layered boride alloys, on the other hand, few electronic calculations have been published, thus prompting the generalization of a well-known electron counting rule -- which is typically used to study molecular organometallics, boranes, and metallocenes -- to predict the trends in the densities of states of crystalline solids that possess the requisite deltahedral bonding geometry. In accordance with these generalized electronic counting rules, alloys of the form RMB4 (R = Y, Gd, Ho; M = Cr, Mo, W) were measured to be n-type semiconductors with band gaps ranging from 0.15 eV to 0.25 eV. These alloys exhibited thermoelectric power factors comparable with those of other potential boride thermoelectric materials reported in the literature. Furthermore, as a result of the procedure developed for precision synthesis of boron-rich intermetallics and the improved understanding of bonding trends, layered borides of several previously overlooked structure-types were synthesized and screened for superconductivity. Consequently, alloys of the MoB4 phase were discovered to be superconducting when doped with Nb or Ti. Electrical resistivity measurements of superconducting transitions between 6 and 8 K in these materials were confirmed via magnetic susceptibility measurements and x-ray diffraction. Structural measurements indicated opposite trends in lattice modification than those reported for the superconducting transition metal diborides.

Developing a Magnetic Circular Dichroism Apparatus Equipped with Neodymium Magnet for Students to Investigate the Electronic Structures of Transition Metals and Lanthanoids

ERIC Educational Resources Information Center

Yakubu, Abdallah; Suzuki, Takayoshi; Kita, Masakazu

2017-01-01

This paper describes the development of a simple magnetic circular dichroism (MCD) apparatus from a wood base and neodymium magnets and its configuration in the Faraday alignment. The applicability and effectiveness of the apparatus for MCD spectra measurements have been examined. The apparatus was used by undergraduate students to conduct MCD…

NEUTRONIC REACTOR FUEL COMPOSITION

DOEpatents

Thurber, W.C.

1961-01-10

Uranium-aluminum alloys in which boron is homogeneously dispersed by adding it as a nickel boride are described. These compositions have particular utility as fuels for neutronic reactors, boron being present as a burnable poison.

[An investigation of lanthanum and other metals levels in blood, urine and hair among residents in the rare earth mining area of a city in China].

PubMed

Bao, T M; Tian, Y; Wang, L X; Wu, T; Lu, L N; Ma, H Y; Wang, L

2018-02-20

Objective: To investigate the levels of lanthanum, cerium, praseodymium, and neodymium in the blood, urine, and hair samples from residents in the rare earth mining area of a city in China, and to provide a scientific basis for the control of rare earth pollution and the protection of population health. Methods: A total of 147 residents who had lived in the rare earth mining area of a city for a long time were selected as the exposure group, and 108 residents in Guyang County of this city who lived 91 km away from the rare earth mining area were selected as the control group. Blood, urine, and hair samples were collected from the residents in both groups. Inductively coupled plasma mass spectrometry was used to determine the content of lanthanum, cerium, praseodymium, and neodymium in blood, urine, and hair samples. Results: In the exposure group, the median levels of lanthanum, cerium, praseodymium, and neodymium were 0.854, 1.724, 0.132, and 0.839 μg/L, respectively, in blood samples, 0.420, 0.920, 0.055, and 0.337 μg/L, respectively, in urine samples, and 0.052, 0.106, 0.012, and 0.045 μg/g, respectively, in hair samples. The exposure group had significantly higher levels of the four rare earth elements in blood, urine, and hair samples than the control group ( P <0.01) . Conclusion: The residents in the rare earth mining area of this city have higher content of lanthanum, cerium, praseodymium, and neodymium in blood, urine, and hair than those in the non-mining area; the content of cerium is highest, followed by lanthanum, neodymium, and praseodymium.

Anomalous stress response of ultrahard WB n compounds

DOE PAGES

Li, Quan; Zhou, Dan; Zheng, Weitao; ...

2015-10-29

Boron-rich tungsten borides are premier prototypes of a new class of ultrahard compounds. Here, we show by first-principles calculations that their stress-strain relations display surprisingly diverse and anomalous behavior under a variety of loading conditions. Most remarkable is the dramatically changing bonding configurations and deformation modes with rising boron concentration in WB n (n=2, 3, 4), resulting in significantly different stress responses and unexpected indentation strength variations. This novel phenomenon stems from the peculiar structural arrangements in tungsten borides driven by boron’s ability to form unusually versatile bonding states. Our results elucidate the intriguing deformation mechanisms that define a distinctmore » type of ultrahard material. Here, these new insights underscore the need to explore unconventional structure-property relations in a broad range of transition-metal light-element compounds.« less

X-Ray photoelectron spectroscopy study of radiofrequency-sputtered titanium, carbide, molybdenum carbide, and titanium boride coatings and their friction properties

NASA Technical Reports Server (NTRS)

Brainard, W. A.; Wheeler, D. R.

1977-01-01

Radiofrequency sputtered coatings of titanium carbide, molybdenum carbide and titanium boride were tested as wear resistant coatings on stainless steel in a pin on disk apparatus. X-ray photoelectron spectroscopy (XPS) was used to analyze the sputtered films with regard to both bulk and interface composition in order to obtain maximum film performance. Significant improvements in friction behavior were obtained when properly biased films were deposited on deliberately preoxidized substrates. XPS depth profile data showed thick graded interfaces for bias deposited films even when adherence was poor. The addition of 10 percent hydrogen to the sputtering gas produced coatings with thin poorly adherent interfaces. Results suggest that some of the common practices in the field of sputtering may be detrimental to achieving maximum adherence and optimum composition for these refractory compounds.

Electronic, structural and magnetic studies of niobium borides of group 8 transition metals, Nb2MB2 (M=Fe, Ru, Os) from first principles calculations

NASA Astrophysics Data System (ADS)

Touzani, Rachid St.; Fokwa, Boniface P. T.

2014-03-01

The Nb2FeB2 phase (U3Si2-type, space group P4/mbm, no. 127) is known for almost 50 years, but until now its magnetic properties have not been investigated. While the synthesis of Nb2OsB2 (space group P4/mnc, no. 128, a twofold superstructure of U3Si2-type) with distorted Nb-layers and Os2-dumbbells was recently achieved, "Nb2RuB2" is still not synthesized and its crystal structure is yet to be revealed. Our first principles density functional theory (DFT) calculations have confirmed not only the experimental structures of Nb2FeB2 and Nb2OsB2, but also predict "Nb2RuB2" to crystalize with the Nb2OsB2 structure type. According to chemical bonding analysis, the homoatomic B-B interactions are optimized and very strong, but relatively strong heteroatomic M-B, B-Nb and M-Nb bonds (M=Fe, Ru, Os) are also found. These interactions, which together build a three-dimensional network, are mainly responsible for the structural stability of these ternary borides. The density-of-states at the Fermi level predicts metallic behavior, as expected, from metal-rich borides. Analysis of possible magnetic structures concluded preferred antiferromagnetic ordering for Nb2FeB2, originating from ferromagnetic interactions within iron chains and antiferromagnetic exchange interactions between them.

Specific features of thermal and magnetic properties of Yb B50 at low temperatures

NASA Astrophysics Data System (ADS)

Novikov, V. V.; Zhemoedov, N. A.; Matovnikov, A. V.; Mitroshenkov, N. V.; Popova, E. A.; Tolstosheev, A. K.; Malkin, B. Z.; Bud'ko, S. L.

2018-05-01

Heat capacity, thermal expansion, and magnetization of ytterbium boride Yb B50 were studied at temperatures 0.6-300 K, 5-300 K, and 2-300 K, respectively. We revealed two smooth peaks at about 4.0 and 60 K in the temperature dependence of the heat capacity. A comparison with the heat capacity of the diamagnetic isostructural boride Lu B50 shows that these anomalies can be attributed to excitations in the ytterbium sublattice (Schottky anomalies). A scheme for splitting of the ground F 7 /2 2 multiplet of Y b3 + ions in the crystal field is proposed. Reliability of the proposed crystal-field energies of the Y b3 + ions is confirmed by the analysis of temperature dependencies of magnetic susceptibility and magnetization in applied magnetic fields up to 55 kOe. A clear anisotropy of the thermal expansion and a negative expansion within a wide temperature range (40-185 K) were observed. Assuming that this anomaly of the thermal expansion in higher borides is caused by the specific thermal evolution of a crystal lattice observed earlier, in particular, in Lu B50 , and the interaction of rare-earth ions with lattice strains, we have determined phenomenological Grüneisen parameters which characterize effects due to thermal transitions of Y b3 + ions between the ground and excited states. A phase transition of Yb B50 to any magnetically ordered state was not observed down to the lowest temperatures of experiments.

Fusion welding of a modern borated stainless steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robino, C.V.; Cieslak, M.J.

1997-01-01

Experiments designed to assess the fabrication and service weldability of 304B4A borated stainless steel were conducted. Welding procedures and parameters for manual gas tungsten arc (GTA) welding, autogenous electron beam (EB) welding and filler-added EB welding were developed and found to be similar to those for austenitic stainless steels. Following the procedure development, four test welds were produced and evaluated by microstructural analysis and Charpy impact testing. Further samples were used for determination of the postweld heat treatment (PWHT) response of the welds. The fusion zone structure of welds in this alloy consists of primary austenite dendrites with an interdendriticmore » eutectic-like austenite/boride constituent. Welds also show an appreciable partially molten zone that consists of the austenite/boride eutectic surrounding unmelted austenite islands. The microstructure of the EB welds was substantially finer than that of the GTA welds, and boride coarsening was not observed in the solid state heat-affected zone (HAZ) of either weld type. The impact toughness of as-welded samples was found to be relatively poor, averaging less than 10 J for both GTA and EB welds. For fusion zone notched GTA and EB samples and centerline notched EB samples, fracture generally occurred along the boundary between the partially molten and solid-state regions of the HAZ. The results of the PWHT study were very encouraging, with typical values of the impact energy for HAZ notched samples approaching 40 J, or twice the minimum code-acceptable value.« less

In vitro analysis of laser meniscectomy.

PubMed

Vangsness, C T; Akl, Y; Nelson, S J; Liaw, L H; Smith, C F; Marshall, G J

1995-01-01

Partial meniscectomies were performed on 32 fresh human meniscal autopsy specimens. The following laser systems were tested: carbon dioxide (CO2), neodymium:yttrium aluminum garnet (Nd:YAG), potassium titanyl phosphate (KTP), holmium:YAG (Ho:YAG), and excimer. Meniscectomies with these lasers were compared with scalpel, mechanical, and electrocautery meniscectomies. Lasers were applied to specimens in and out of normal saline. Routine hematoxylin and eosin and sirius red sections were prepared for each specimen, and the depths of thermal changes were analyzed. Scanning electron microscopy was used to visualize the meniscectomy interface. Among these specimens, the scalpel and mechanical meniscectomies showed the least extension of cellular changes (range, 10-15 nm). The excimer laser caused the least tissue changes of the lasers tested. Tissue changes were less extensive with the pulsed CO2 laser than with the holmium:YAG, neodymium:YAG, and KTP lasers. Scanning electron microscopy showed that use of the scalpel meniscectomy resulted in the smoothest meniscectomy edge, followed by use of the excimer, CO2, holmium:YAG, neodymium:YAG, and KTP lasers. The most surface disruption occurred with electrocautery. Meniscectomies under saline required more energy and took longer in each case, with the holmium:YAG, neodymium:YAG, and CO2 laser cutting the best. Saline meniscectomies showed less thermal change. The CO2 and KTP lasers cut best in air.

Chromatographic extraction with di(2-ethylhexyl)orthophosphoric acid for production and purification of promethium-147

DOEpatents

Boll, Rose A [Knoxville, TN; Mirzadeh, Saed [Knoxville, TN

2008-10-14

A method of producing and purifying promethium-147 including the steps of: irradiating a target material including neodymium-146 with neutrons to produce promethium-147 within the irradiated target material; dissolving the irradiated target material to form an acidic solution; loading the acidic solution onto a chromatographic separation apparatus containing HDEHP; and eluting the apparatus to chromatographically separate the promethium-147 from the neodymium-146.

Parametric study of laser photovoltaic energy converters

NASA Technical Reports Server (NTRS)

Walker, G. H.; Heinbockel, J. H.

1987-01-01

Photovoltaic converters are of interest for converting laser power to electrical power in a space-based laser power system. This paper describes a model for photovoltaic laser converters and the application of this model to a neodymium laser silicon photovoltaic converter system. A parametric study which defines the sensitivity of the photovoltaic parameters is described. An optimized silicon photovoltaic converter has an efficiency greater than 50 percent for 1000 W/sq cm of neodymium laser radiation.

Power Systems and Energy Storage Modeling for Directed Energy Weapons

DTIC Science & Technology

2014-06-01

neodymium or ytterbium doped yttrium aluminum garnet (YAG) crystal.6 The Maritime Laser Demonstration (MLD) features several 15 kW slab lasers combined...The laser substrate is similar to a fiber optic cable that is doped with a rare earth element (typically neodymium or ytterbium); many fibers can be...but with different elements. A typical construction consists of a sheet of Lithium- cobalt -oxide and a sheet of carbon separated by an insulator

The physical and mechanical metallurgy of advanced O+BCC titanium alloys

NASA Astrophysics Data System (ADS)

Cowen, Christopher John

This thesis comprises a systematic study of the microstructural evolution, phase transformation behavior, elevated-temperature creep behavior, room-temperature and elevated-temperature tensile behavior, and room-temperature fatigue behavior of advanced titanium-aluminum-niobium (Ti-Al-Nb) alloys with and without boron additions. The specific alloys studied were: Ti-5A1-45Nb (at%), Ti-15Al-33Nb (at%), Ti-15Al-33Nb-0.5B (at%), Ti-15Al-33Nb-5B (at%), Ti-21Al-29Nb (at%), Ti-22Al-26Nb (at%), and Ti-22Al-26Nb-5B (at%). The only alloy composition that had been previously studied before this thesis work began was Ti-22Al-26Nb (at%). Publication in peer-reviewed material science journals of the work performed in this thesis has made data available in the scientific literature that was previously non-existent. The knowledge gap for Ti-Al-Nb phase equilibria over the compositional range of Ti-23Al-27Nb (at%) to Ti-12Al-38Nb (at%) that existed before this work began was successfully filled. The addition of 5 at% boron to the Ti-15Al-33Nb alloy produced 5-9 volume percent boride phase needles within the microstructure. The chemical composition of the boride phase measured by electron microprobe was determined to be approximately B 2TiNb. The lattice parameters of the boride phase were simulated through density functional theory calculations by collaborators at the Air Force Research Laboratory based on the measured composition. Using the simulated lattice parameters, electron backscatter diffraction kikuchi patterns and selected area electron diffraction patterns obtained from the boride phase were successfully indexed according to the space group and site occupancies of the B27 orthorhombic crystal structure. This suggests that half the Ti (c) Wyckoff positions are occupied by Ti atoms and the other half are occupied by Nb atoms in the boride phase lattice. Creep deformation behavior is the main focus of this thesis and in particular understanding the dominant creep deformation mechanisms as a function of stress, temperature, and strain rate. Microstructure-creep relationships for Ti-Al-Nb-xB alloys were developed with the understanding gained. A rule-of-mixtures empirical model based on constituent phase volume fractions and strain rates was developed to predict the minimum creep rates of two-phase O+BCC microstructures. The most innovative results of this thesis were produced through the development of an in-situ creep testing methodology. The creep deformation evolution was chronicled in-situ during high temperature creep experiments, while creep displacement versus time data was simultaneously obtained. The in-situ experiments revealed that prior-BCC grain boundaries were the locus of damage accumulation during creep deformation. A methodology that allows in-situ observation of surface creep deformation as a function of creep displacement has yet to be presented in the literature.

Magnetism and structural chemistry of ternary borides RE2MB 6 ( RE = rare earth, M = Ru, Os)

NASA Astrophysics Data System (ADS)

Hiebl, K.; Rogl, P.; Nowotny, H.

1984-10-01

The magnetic behavior of the ternary borides RE2RuB 6 and RE2OsB 6 ( RE = Y, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) was studied in the temperature range 1.5 K < T < 1100 K. All compounds crystallize with the Y 2ReB 6-type structure and are characterized by direct RE- RE contacts and the formation of planar infinite two-dimensional rigid boron nets. The magnetic properties reveal a typical Van Vleck paramagnetism of free RE3+-ions at temperatures higher than 200 K with ferromagnetic interaction in the low-temperature range T < 55 K. The ferromagnetic ordering temperatures vary with the De Gennes factor. There is no indication for a magnetic contribution from the Ru(Os)-sublattice. Above 1.8 K none of the samples were found to be superconducting.

Electronic structure and mechanical properties of osmium borides, carbides and nitrides from first principles

NASA Astrophysics Data System (ADS)

Liang, Yongcheng; Zhao, Jianzhi; Zhang, Bin

2008-06-01

The stabilities, mechanical properties and electronic structures of osmium boride (OsB), carbide (OsC) and nitride (OsN), in the tungsten carbide (WC), rocksalt (NaCl), cesium chloride (CsCl) and zinc blende (ZnS) structures respectively, are systematically predicted by calculations from first-principles. Only four phases, namely, OsB(WC), OsB(CsCl), OsC(WC), and OsC(ZnS), are mechanically stable, and none is a superhard compound, contrary to previous speculation. Most importantly, we find that the changing trends of bulk modulus and shear modulus are completely different for OsB, OsC and OsN in same hexagonal WC structure, which indicates that the underlying sources of hardness and incompressibility are fundamentally different: the former is determined by bonding nature while the latter is closely associated with valence electron density.

The Influence of Nano-Scale Silicon Nitride Additions on the Physical and Magnetic Properties of Iron Sheathed Magnesium Boride Wires

NASA Astrophysics Data System (ADS)

Zhu, W.; Cave, J.

2006-03-01

The enhancement of flux line pinning in magnesium boride wires is a critical issue for their future applications in devices and machines. It is well known that small size dopants can significantly influence the current densities of these materials. Here, the influence of nanometric (<30nm) silicon nitride on physical properties and current density is presented. The iron-sheathed powder in tube wires were prepared using pure magnesium and boron powders with silicon nitride additions. The wires were rolled flat and treated at up to 900 degrees C in flowing argon. SEM and XRD were used to identify phases and microstructures. Magnetization critical currents, up to several 100 of thousands A/cm2, at various temperatures and fields (5K - 20K and up to 3 tesla) show that there are competing mechanisms from chemical and flux pinning effects.

Magnetic and magnetothermal studies of iron boride (FeB) nanoparticles

NASA Astrophysics Data System (ADS)

Hamayun, M. Asif; Abramchuk, Mykola; Alnasir, Hisham; Khan, Mohsin; Pak, Chongin; Lenhert, Steven; Ghazanfari, Lida; Shatruk, Michael; Manzoor, Sadia

2018-04-01

We report magnetic and magnetothermal properties of iron boride (FeB) nanoparticles prepared by surfactant-assisted ball milling of arc-melted bulk ingots of this binary alloy. Size-dependent magnetic properties were used to identify the transition to the single domain limit and calculate the anisotropy and exchange stiffness constants for this system. Extended milling is seen to produce coercivity enhancement and exchange bias of up to 270 Ôe at room temperature. The magnetothermal properties were investigated by measuring the response of single domain FeB nanoparticles to externally applied ac magnetic fields. All investigated particle sizes show a significant heating response, demonstrating their potential as candidates for magnetically induced hyperthermia. FeB nanoparticles were encapsulated into lipophilic domains of liposomes as evidenced by TEM. Exposure of HeLa cells to these liposomes did not affect cell viability, suggesting the biocompatibility of these new magnetic nanomaterials.

Identification of delamination failure of boride layer on common Cr-based steels

NASA Astrophysics Data System (ADS)

Taktak, Sukru; Tasgetiren, Suleyman

2006-10-01

Adhesion is an important aspect in the reliability of coated components. With low-adhesion of interfaces, different crack paths may develop depending on the local stress field at the interface and the fracture toughness of the coating, substrate, and interface. In the current study, an attempt has been made to identify the delamination failure of coated Cr-based steels by boronizing. For this reason, two commonly used steels (AISI H13, AISI 304) are considered. The steels contain 5.3 and 18.3 wt.% Cr, respectively. Boriding treatment is carried out in a slurry salt bath consisting of borax, boric acid, and ferrosilicon at a temperature range of 800 950 °C for 3, 5, and 7 h. The general properties of the boron coating are obtained by mechanical and metallographic characterization tests. For identification of coating layer failure, some fracture toughness tests and the Daimler-Benz Rockwell-C adhesion test are used.

[Neodymium magnet injury causing nasal fracture: a case report].

PubMed

Aykan, Andaç; Güzey, Serbülent; Avşar, Sedat; Öztürk, Serdar

2015-05-01

In parallel with technological developments, small size but strong magnets are commonly used in modern devices. In terms of foreign body injuries, magnet injuries are quite rare. However, due to their unique characteristics, there are some difficulties in their management. The magnetic field generated by the magnet affects the surgical instruments and make treatment difficult. In this case report, a nasal injury due to neodymium magnet and our alternative approach for its management was reported.

Treatment Outcomes of Long-Pulsed Nd: YAG Laser for Two Different Subtypes of Rosacea

PubMed Central

Say, Ekin Mese; Gökdemir, Gonca

2015-01-01

Background: A variety of lasers have been used for the treatment of rosacea. However, treatment of this condition with long-pulsed neodymium-doped yttrium aluminium garnet laser has not been reported yet. Objective: To assess the efficacy and safety of long-pulsed neodymium-doped yttrium aluminium garnet laser in two different subtypes (erythematotelangiectatic and papulopustular) of rosacea. Methods: A total of 66 patients were enrolled in the study. All of the patients were treated with long-pulsed neodymium-doped yttrium aluminium garnet laser with 3- to 4-week intervals. Rosacea severity score was assessed by using photographs. Improvement in severity was defined as the percentage reduction in severity scores from baseline to the end of treatment. Patients were also asked about their own opinions of improvement at the end of the treatment. Side effects were also documented. Results: Good to excellent improvement was achieved in up to 50 percent of the patients in the erythematotelangiectatic and papulopustular groups. Percent improvement of global severity was significantly greater in the erythematotelangiectatic patients than in the papulopustular patients. The majority of patients from both groups noted a significant improvement of the lesions. Hypopigmented atrophic scars were seen in two patients. Conclusion: The long-pulsed neodymium-doped yttrium aluminium garnet laser is a safe and effective treatment for vascular and inflammatory lesions of rosacea. PMID:26430486

The efficacy of facial skin cancer treatment with high-energy pulsed neodymium and Nd:YAG lasers.

PubMed

Moskalik, Konstantin; Kozlov, Alexander; Demin, Eugeny; Boiko, Ernest

2009-04-01

The aim of this study was to assess the curative and cosmetic efficacy of treatment for facial skin cancer using neodymium laser irradiation. Due to the complex anatomy of the area, therapy for facial skin cancer is difficult. Laser irradiation was used for the treatment of 3461 patients with 3624 facial skin cancer lesions of stages T(1-2)N(0)M(0:) 3346 basal cell skin cancers, 188 limited basal cell skin cancer recurrences, and 90 squamous cell skin cancers. Pulsed neodymium (Nd) and Nd:YAG lasers were used as the energy sources. The patients were followed-up from 3 mo to 5 y or more. Patients with basal cell skin cancer treated by irradiation with the Nd laser developed recurrences in 1.8% of cases, and patients treated with the Nd:YAG laser had a recurrence rate of 2.5%. Recurrences following treatment for basal cell skin cancer, and those of squamous cell skin cancer, after irradiation with the Nd laser appeared in 3.7% and 4.4% of patients, respectively. Overall, the frequency of facial skin cancer recurrences after treatment with laser irradiation was 2.1% of all the irradiated tumors. Neodymium laser irradiation is an effective method to treat facial skin cancer of stages T(1-2)N(0)M(0), and results in acceptable cosmetic results.

Effect of Discharge Time on Plasma Electrolytic Borocarbonitriding of Pure Iron

NASA Astrophysics Data System (ADS)

Jin, Xiaoyue; Wu, Jie; Wang, Bin; Yang, Xuan; Chen, Lin; Qu, Yao; Xue, Wenbin

The plasma electrolytic borocarbonitriding (PEB/C/N) process on pure iron was carried out in 25% borax solution with glycerine and carbamide additives under different discharge time at 360V. The morphology and structure of PEB/C/N hardened layers were analyzed by SEM and XRD. The hardness profiles of hardened layers were measured by microhardness test. Corrosion behavior of PEB/C/N layers was evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Their wear performance was carried out using a pin-disc friction and wear tester under dry sliding test. The PEB/C/N samples mainly consisted of α-Fe, Fe2B, Fe3C, FeN, FeB, Fe2O3 and Fe4N phases, and the Fe2B phase was the dominant phase in the boride layer. It was found that the thickness of boride layer increased with the discharge time and reached 14μm after 60min treatment. The microhardness of the boride layer was up to 2100HV, which was much higher than that of the bare pure iron (about 150HV). After PEB/C/N treatment, the corrosion resistance of pure iron was slightly improved. The friction coefficient of PEB/C/N treated pure iron decreased to 0.129 from 0.556 of pure iron substrate. The wear rate of the PEB/C/N layer after 60min under dry sliding against ZrO2 ball was only 1/10 of that of the bare pure iron. The PEB/C/N treatment is an effective way to improve the wear behavior of pure iron.

Correlation between structural stability of LiBH4 and cation electronegativity in metal borides: an experimental insight for catalyst design.

PubMed

Cai, Weitong; Yang, Yuanzheng; Tao, Pingjun; Ouyang, Liuzhang; Wang, Hui

2018-04-03

Nanosized metal borides MBx (M = Mg, Ti, Fe, Si) are found to play an important role in enhancing the hydrogen storage performance of LiBH4 in this work. The hydrogen storage behavior and mechanism of these modified systems are investigated through TPD-MS, XRD, FTIR and SEM characterization methods. By introducing these metal borides into LiBH4 through ball milling, the systems display three dehydrogenation stages disclosing their similarity and distinction. The 1st stage starts at 190 °C, the 2nd stage ranges from 280 °C to 400 °C and the 3rd stage ends at 550 °C with a peak at round 440 °C similar to that of pristine LiBH4. Distinguishing features exist at the 2nd stage revealing the effectiveness of MBx in an order of MgB2 < TiB2 < FeB < SiB4. Significantly, reversibility up to 9.7 wt% is achieved from LiBH4 with assistance of SiB4. The catalytic effect of MBx is influenced by the Pauling electronegativity of M in MBx and the interfacial contact characteristic between LiBH4 and MBx. The larger electronegativity leads to an enhanced catalytic effect and consequently lower temperature at the major stage. In contrast to the components in the solid state, the molten LiBH4 promotes a catalytic effect due to a superior interfacial contact. These results provide an insight into designing high-performance catalysts applied to LiBH4 as a hydrogen storage material.

Boron-Based Hydrogen Storage: Ternary Borides and Beyond

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vajo, John J.

DOE continues to seek reversible solid-state hydrogen materials with hydrogen densities of ≥11 wt% and ≥80 g/L that can deliver hydrogen and be recharged at moderate temperatures (≤100 °C) and pressures (≤100 bar) enabling incorporation into hydrogen storage systems suitable for transportation applications. Boron-based hydrogen storage materials have the potential to meet the density requirements given boron’s low atomic weight, high chemical valance, and versatile chemistry. However, the rates of hydrogen exchange in boron-based compounds are thus far much too slow for practical applications. Although contributing to the high hydrogen densities, the high valance of boron also leads to slowmore » rates of hydrogen exchange due to extensive boron-boron atom rearrangements during hydrogen cycling. This rearrangement often leads to multiple solid phases occurring over hydrogen release and recharge cycles. These phases must nucleate and react with each other across solid-solid phase boundaries leading to energy barriers that slow the rates of hydrogen exchange. This project sought to overcome the slow rates of hydrogen exchange in boron-based hydrogen storage materials by minimizing the number of solid phases and the boron atom rearrangement over a hydrogen release and recharge cycle. Two novel approaches were explored: 1) developing matched pairs of ternary borides and mixed-metal borohydrides that could exchange hydrogen with only one hydrogenated phase (the mixed-metal borohydride) and only one dehydrogenated phase (the ternary boride); and 2) developing boranes that could release hydrogen by being lithiated using lithium hydride with no boron-boron atom rearrangement.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sitler, Steven J.; Raja, Krishnan S.; Charit, Indrajit

Solid solutions of HfB 2-ZrB 2 mixtures were prepared by high-energy ball milling of diboride and additive powders followed by spark plasma sintering (SPS). A mixture of stoichiometric 1:1 HfB 2-ZrB 2 borides was the base composition to which Hf, Zr, Ta, LaB 6 or Gd 2O 3 was added. Hf, Zr and Ta were added in order to bring the boron-to-metal ratio down to 1.86, rendering the boride as MeB 1.86. In the case of LaB 6 and Gd 2O 3, 1.8 mol% was added. Electroanalytical behavior of hydrogen evolution reactions was evaluated in 1 M H 2SO 4more » and 1 M NaOH solutions. The LaB 6 additive material showed Tafel slopes of 125 and 90 mV/decade in acidic and alkaline solutions respectively. The Hf and Zr rich samples showed Tafel slopes of about 120 mV/decade in both electrolytes. The over potentials of hydrogen evolution reactions (at 10 mA/cm 2) in the alkaline solution were about 100 mV lower than those in acidic solution. The metal-rich diborides and addition of LaB 6 showed better hydrogen evolution reaction (HER) activities than the base 1:1 HfB 2-ZrB 2 stoichiometric diboride solid solution. Furthermore, the higher activity of metal-rich borides could be attributed to the increased electron population at the d-orbitals of the metal shown by band structure modeling calculations using the Density Functional Theory approach.« less

Photovoltaic cell

DOEpatents

Gordon, Roy G.; Kurtz, Sarah

1984-11-27

In a photovoltaic cell structure containing a visibly transparent, electrically conductive first layer of metal oxide, and a light-absorbing semiconductive photovoltaic second layer, the improvement comprising a thin layer of transition metal nitride, carbide or boride interposed between said first and second layers.

Watt-level single-frequency tunable neodymium MOPA fiber laser operating at 915-937 nm

NASA Astrophysics Data System (ADS)

Rota-Rodrigo, S.; Gouhier, B.; Laroche, M.; Zhao, J.; Canuel, B.; Bertoldi, A.; Bouyer, P.; Traynor, N.; Cadier, B.; Robin, T.; Santarelli, G.

2018-02-01

We have developed a Watt-level single-frequency tunable fiber laser in the 915-937 nm spectral window. The laser is based on a neodymium-doped fiber master oscillator power amplifier architecture, with two amplification stages using a 20 mW extended cavity diode laser as seed. The system output power is higher than 2 W from 921 to 933 nm, with a stability better than 1.4% and a low relative intensity noise.

LASERS: Ultimate energy parameters of the radiation emitted from neodymium-glass laser systems

NASA Astrophysics Data System (ADS)

Eshmemet'eva, E. V.; Korolev, V. I.; Mesnyankin, E. P.; Serebryakov, V. A.; Shashkin, V. V.; Yashin, V. E.

1992-09-01

An experimental investigation was made of the energy conversion efficiency and of the effects of stimulated Brillouin scattering and of optical breakdown, limiting the maximum energy density obtained from several phosphate and silicate neodymium glasses when the duration of the output pulses was 50-150 ns. The experimental results were used to develop a numerical model for calculation of the gain allowing for these processes. A design was developed for an amplifier with ultimate radiation characteristics.

Neodymium: YAG lasers. An FDA report.

PubMed

Stark, W J; Worthen, D; Holladay, J T; Murray, G

1985-02-01

Analysis of data from four neodymium:YAG laser manufacturers submitted to the Food and Drug Administration (FDA) on over 17,000 cases indicate the procedure is safe and effective for cutting opaque posterior lens capsules. A successful opening in the pupillary membrane was achieved in 98% of the cases, and vision improved in 84% of the cases. Clinically significant risks include: a rise in intraocular pressure two to four hours after treatment, damage to the intraocular lens, and rupture of the anterior hyaloid face.

High Energy Solid State and Free Electron Laser Systems in Tactical Aviation

DTIC Science & Technology

2005-06-01

specifically neodymium and ytterbium doped yttrium aluminum garnet (Nd:YAG and Yb:YAG) have been shown to produce pump absorption efficiencies (i.e...Search Radar Dish Aluminum Alloy 2.71 10.0 0.91 321 932 300 22.1 SAM nosecone Ceramic* 3.0 1.0 0.9 1600 3300 250 12.1 T-72 Tank Armor Steel...development at Lawrence Livermore National Laboratory, is the solid-state heat capacity laser, which is an array of diode- pumped neodymium-doped gadolinium

Global patterns of dust and bedrock nutrient supply to montane ecosystems

PubMed Central

Arvin, Lindsay J.; Riebe, Clifford S.; Aciego, Sarah M.; Blakowski, Molly A.

2017-01-01

A global compilation of erosion rates and modeled dust fluxes shows that dust inputs can be a large fraction of total soil inputs, particularly when erosion is slow and soil residence time is therefore long. These observations suggest that dust-derived nutrients can be vital to montane ecosystems, even when nutrient supply from bedrock is substantial. We tested this hypothesis using neodymium isotopes as a tracer of mineral phosphorus contributions to vegetation in the Sierra Nevada, California, where rates of erosion and dust deposition are both intermediate within the global compilation. Neodymium isotopes in pine needles, dust, and bedrock show that dust contributes most of the neodymium in vegetation at the site. Together, the global data sets and isotopic tracers confirm the ecological significance of dust in eroding mountain landscapes. This challenges conventional assumptions about dust-derived nutrients, expanding the plausible range of dust-reliant ecosystems to include many temperate montane regions, despite their relatively high rates of erosion and bedrock nutrient supply. PMID:29226246

Design and Implementation of a Hall Effect Sensor Array Applied to Recycling Hard Drive Magnets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kisner, Roger; Lenarduzzi, Roberto; Killough, Stephen M

Rare earths are an important resource for many electronic components and technologies. Examples abound including Neodymium magnets used in mobile devices and computer hard drives (HDDs), and a variety of renewable energy technologies (e.g., wind turbines). Approximately 21,000 metric tons of Neodymium is processed annually with less than 1% being recycled. An economic system to assist in the recycling of magnet material from post-consumer goods, such as Neodymium Iron Boron magnets commonly found in hard drives is presented. A central component of this recycling measurement system uses an array of 128 Hall Effect sensors arranged in two columns to detectmore » the magnetic flux lines orthogonal to the HDD. Results of using the system to scan planar shaped objects such as hard drives to identify and spatially locate rare-earth magnets for removal and recycling from HDDs are presented. Applications of the sensor array in other identification and localization of magnetic components and assemblies will be presented.« less

Abundance analysis of neodymium in the solar atmosphere

NASA Astrophysics Data System (ADS)

Abdelkawy, Ali G. A.; Shaltout, Abdelrazek M. K.; Beheary, M. M.; Bakry, A.

2017-10-01

Based on non-local thermodynamical equilibrium (NLTE) calculations, the solar neodymium (Nd) content was found based on a model atom of singly ionized neodymium (Nd II) containing 153 energy levels and 42 line transitions plus the ground state of Nd III. Here, we re-derive the solar Nd abundance using the model of the solar photosphere of Holweger & Müller.We succeed in selecting a good sample line list, relying on 20 Nd II solar lines together with the most accurate transition probabilities measured experimentally and available observational data. With damping parameters obtained from the literature, we find a mean NLTE solar photospheric Nd abundance of log ɛNd(1D) = 1.43 ± 0.16, which is in excellent agreement with the meteoritic value (log ɛNd = 1.45 ± 0.02). For a set of selected Nd II lines, the NLTE abundance correction is found to be +0.01 dex compared with the standard LTE effect. The influence of collisional interactions with electrons and neutral hydrogen atoms is investigated in detail.

FT-IR Spectroscopic Evidence Of Phase Transition For NaA-ROH-Kerosine-H2O Microemulsion System Containing Nd3+ Ions

NASA Astrophysics Data System (ADS)

Liao, Hua; Xu, Zhen-Hua; Shi, Nai; Wu, Jin-Guang; Xu, Guang-Xian

1989-12-01

In the previous investigation, the saponification of naphthenic acid extractant system has been proved to be a process of the formation of a microemulsion of 14/0 type, and its full extraction of rare earths is a process of destruction of the W/O microemulsion[1]. When NdCl3 is partially extracted with NaA (sodium naphthenate) secoctylalcohol-- kerosine-- water microemulsion system (ME), both the NdA3 and the NaA co-exist in the same organic phase. However,the formation mechanism of microemulsion containing neodymium has not been much studied. In this paper, 10 aliquots of fully saponificated extractants were equilibrated with various amounts of NdC13 solutions respectively, then ten organic phases with different extraction efficiencies of neodymium from 094 to 9094 were obtained. After extraction,the volume of neodymium containing organic phase increased by 5 to 4594, because of the transfer of water molecules. The appearance of these organic phase still remained clear and transparent. The average hydrodynamic radius of the drops were found to be 100-300 Angstrom by using light scattering techniques. The results give a direct evidence of the microemulsion formation in the organic phase. Their FT-IR spectra were measured with CaFa liquid cells utilizing a Nicolet 7199B FT-IR spectrometer. The presence of various amounts of water in the organic phases was clearly detected from the relative intensity changes of 1644 cm-I, which is assigned to the bending mode of 1110 molecules. Fig.1 shows the change of water contents to the percent extraction of neodymium. Comparsion with the FT-IR spectra, it is seen that the 1560 cm-1 peak of the full saponificated extractant is attributed to the asym. stretching vibration of COO''' group, it shifted to 1536 for 100% extration of Nd ions, indicating the formation of neodymium naphthenate (NdA ) from ionic sodium naphthenate. The sym. strethching vibration of COO''' located at 1406 cm-1, it shifted to 1408 cm in 45% Nd extration. and disappeared when the percentage extration of Nd3+ was larger than 50%, at the same time, the water content dropped sharply (Fig.1).These results suggested that a series of microemulsion containing Nd ions formed in these organic phases, at the transition region ( more than 50 percentage extration of neodymium), a morphological change of the W/0 dispersion system might occur.

DFT investigations of hydrogen storage materials

NASA Astrophysics Data System (ADS)

Wang, Gang

Hydrogen serves as a promising new energy source having no pollution and abundant on earth. However the most difficult problem of applying hydrogen is to store it effectively and safely, which is smartly resolved by attempting to keep hydrogen in some metal hydrides to reach a high hydrogen density in a safe way. There are several promising metal hydrides, the thermodynamic and chemical properties of which are to be investigated in this dissertation. Sodium alanate (NaAlH4) is one of the promising metal hydrides with high hydrogen storage capacity around 7.4 wt. % and relatively low decomposition temperature of around 100 °C with proper catalyst. Sodium hydride is a product of the decomposition of NaAlH4 that may affect the dynamics of NaAlH4. The two materials with oxygen contamination such as OH- may influence the kinetics of the dehydriding/rehydriding processes. Thus the solid solubility of OH - groups (NaOH) in NaAlH4 and NaH is studied theoretically by DFT calculations. Magnesium boride [Mg(BH4)2] is has higher hydrogen capacity about 14.9 wt. % and the decomposition temparture of around 250 °C. However one flaw restraining its application is that some polyboron compounds like MgB12H12 preventing from further release of hydrogen. Adding some transition metals that form magnesium transition metal ternary borohydride [MgaTMb(BH4)c] may simply the decomposition process to release hydrogen with ternary borides (MgaTMbBc). The search for the probable ternary borides and the corresponding pseudo phase diagrams as well as the decomposition thermodynamics are performed using DFT calculations and GCLP method to present some possible candidates.

Metallic Borides, La 2 Re 3 B 7 and La 3 Re 2 B 5 , Featuring Extensive Boron–Boron Bonding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bugaris, Daniel E.; Malliakas, Christos D.; Chung, Duck Young

We synthesized La 2Re 3B 7 and La 3Re 2B 5 in single-crystalline form from a molten La/Ni eutectic at 1000°C, in the first example of the flux crystal growth of ternary rare-earth rhenium borides. Both compounds crystallize in their own orthorhombic structure types, with La 2Re 3B 7 (space group Pcca) having lattice parameters a = 7.657(2) Å, b = 6.755(1) Å, and c = 11.617(2) Å, and La 3Re 2B 5 (space group Pmma) having lattice parameters a = 10.809(2) Å, b = 5.287(1) Å, and c = 5.747(1) Å. Furthermore, the compounds possess three-dimensional framework structures thatmore » are built up from rhenium boride polyhedra and boron-boron bonding. La 3Re 2B 5 features fairly common B 2 dumbbells, whereas La 2Re 3B 7 has unique one-dimensional subunits composed of alternating triangular B3 and trans-B4 zigzag chain fragments. Also observed in La 3Re 2B 5 is an unusual coordination of B by an octahedron of La atoms. Electronic band structure calculations predict that La 2Re 3B 7 is a semimetal, which is observed in the electrical resistivity data as measured on single crystals, with behavior obeying the Bloch-Grüneisen model and a room-temperature resistivity ρ300K of ~ 375 μΩ cm. The electronic band structure calculations also suggest that La 3Re 2B 5 is a regular metal.« less

Metallic Borides, La 2 Re 3 B 7 and La 3 Re 2 B 5 , Featuring Extensive Boron–Boron Bonding

DOE PAGES

Bugaris, Daniel E.; Malliakas, Christos D.; Chung, Duck Young; ...

2016-01-26

We synthesized La 2Re 3B 7 and La 3Re 2B 5 in single-crystalline form from a molten La/Ni eutectic at 1000°C, in the first example of the flux crystal growth of ternary rare-earth rhenium borides. Both compounds crystallize in their own orthorhombic structure types, with La 2Re 3B 7 (space group Pcca) having lattice parameters a = 7.657(2) Å, b = 6.755(1) Å, and c = 11.617(2) Å, and La 3Re 2B 5 (space group Pmma) having lattice parameters a = 10.809(2) Å, b = 5.287(1) Å, and c = 5.747(1) Å. Furthermore, the compounds possess three-dimensional framework structures thatmore » are built up from rhenium boride polyhedra and boron-boron bonding. La 3Re 2B 5 features fairly common B 2 dumbbells, whereas La 2Re 3B 7 has unique one-dimensional subunits composed of alternating triangular B3 and trans-B4 zigzag chain fragments. Also observed in La 3Re 2B 5 is an unusual coordination of B by an octahedron of La atoms. Electronic band structure calculations predict that La 2Re 3B 7 is a semimetal, which is observed in the electrical resistivity data as measured on single crystals, with behavior obeying the Bloch-Grüneisen model and a room-temperature resistivity ρ300K of ~ 375 μΩ cm. The electronic band structure calculations also suggest that La 3Re 2B 5 is a regular metal.« less

Metal-Rich Transition Metal Diborides as Electrocatalysts for Hydrogen Evolution Reactions in a Wide Range of pH

DOE PAGES

Sitler, Steven J.; Raja, Krishnan S.; Charit, Indrajit

2016-09-23

Solid solutions of HfB 2-ZrB 2 mixtures were prepared by high-energy ball milling of diboride and additive powders followed by spark plasma sintering (SPS). A mixture of stoichiometric 1:1 HfB 2-ZrB 2 borides was the base composition to which Hf, Zr, Ta, LaB 6 or Gd 2O 3 was added. Hf, Zr and Ta were added in order to bring the boron-to-metal ratio down to 1.86, rendering the boride as MeB 1.86. In the case of LaB 6 and Gd 2O 3, 1.8 mol% was added. Electroanalytical behavior of hydrogen evolution reactions was evaluated in 1 M H 2SO 4more » and 1 M NaOH solutions. The LaB 6 additive material showed Tafel slopes of 125 and 90 mV/decade in acidic and alkaline solutions respectively. The Hf and Zr rich samples showed Tafel slopes of about 120 mV/decade in both electrolytes. The over potentials of hydrogen evolution reactions (at 10 mA/cm 2) in the alkaline solution were about 100 mV lower than those in acidic solution. The metal-rich diborides and addition of LaB 6 showed better hydrogen evolution reaction (HER) activities than the base 1:1 HfB 2-ZrB 2 stoichiometric diboride solid solution. Furthermore, the higher activity of metal-rich borides could be attributed to the increased electron population at the d-orbitals of the metal shown by band structure modeling calculations using the Density Functional Theory approach.« less

Thermal properties of zirconium diboride -- transition metal boride solid solutions

NASA Astrophysics Data System (ADS)

McClane, Devon Lee

This research focuses on the thermal properties of zirconium diboride (ZrB2) based ceramics. The overall goal was to improve the understanding of how different transition metal (TM) additives influence thermal transport in ZrB2. To achieve this, ZrB2 with 0.5 wt% carbon, and 3 mol% of individual transition metal borides, was densified by hot-press sintering. The transition metals that were investigated were: Y, Ti, Hf, V, Nb, Ta, Cr, Mo, W, and Re. The room temperature thermal diffusivities of the compositions ranged from 0.331 cm2/s for nominally pure ZrB2 to 0.105 cm2/s for (Zr,Cr)B2 and converged around 0.155cm2/s at higher temperatures for all compositions. Thermal conductivities were calculated from the diffusivities, using temperature-dependent values for density and heat capacity. The electron contribution to thermal conductivity was calculated from measured electrical resistivity according to the Wiedemann-Franz law. The phonon contribution to thermal conductivity was calculated by subtracting the electron contribution from the total thermal conductivity. Rietveld refinement of x-ray diffraction data was used to determine the lattice parameters of the compositions. The decrease in thermal conductivity for individual additives correlated directly to the metallic radius of the additive. Additional strain appeared to exist for additives when the stable TM boride for that metal had different crystal symmetries than ZrB2. This research provided insight into how additives and impurities affect thermal transport in ZrB2. The research potentially offers a basis for future modeling of thermal conductivity in ultra-high temperature ceramics based on the correlation between metallic radius and the decrease in thermal conductivity.

Evidence for extreme mantle fractionation in early Archaean ultramafic rocks from northern Labrador

NASA Technical Reports Server (NTRS)

Collerson, Kenneth D.; Campbell, Lisa M.; Weaver, Barry L.; Palacz, Zenon A.

1991-01-01

Samarium-neodymium isotope data for tectonically interleaved fragments of lithospheric mantle and meta-komatiite from the North Atlantic craton provide the first direct record of mantle differentiation before 3,800 Myr ago. The results confirm the magnitude of light-rare-earth-element depletion in the early mantle, and also its depleted neodymium isotope composition. The mantle fragments were able to retain these ancient geochemical signatures by virtue of having been tectonically incorporated in buoyant felsic crust, thus escaping recycling and homogenization by mantle convection.

LaF3 core/shell nanoparticles for subcutaneous heating and thermal sensing in the second biological-window

NASA Astrophysics Data System (ADS)

Ximendes, Erving Clayton; Rocha, Uéslen; Kumar, Kagola Upendra; Jacinto, Carlos; Jaque, Daniel

2016-06-01

We report on Ytterbium and Neodymium codoped LaF3 core/shell nanoparticles capable of simultaneous heating and thermal sensing under single beam infrared laser excitation. Efficient light-to-heat conversion is produced at the Neodymium highly doped shell due to non-radiative de-excitations. Thermal sensing is provided by the temperature dependent Nd3+ → Yb3+ energy transfer processes taking place at the core/shell interface. The potential application of these core/shell multifunctional nanoparticles for controlled photothermal subcutaneous treatments is also demonstrated.

Large-mode-area single-mode-output Neodymium-doped silicate glass all-solid photonic crystal fiber

PubMed Central

Li, Wentao; Chen, Danping; Qinling, Zhou; Hu, Lili

2015-01-01

We have demonstrated a 45 μm core diameter Neodymium-doped all-solid silicate glass photonic crystal fiber laser with a single mode laser output. The structure parameters and modes information of the fiber are both demonstrated by theoretical calculations using Finite Difference Time Domain (FDTD) method and experimental measurements. Maximum 0.8 W output power limited by launched pump power has been generated in 1064 nm with laser beam quality factor M2 1.18. PMID:26205850

Optical characterization of Nd (3+):AgBr.

PubMed

Bunimovich, D; Nagli, L; Katzir, A

1997-10-20

The luminescence of silver bromide crystals, doped with neodymium, was investigated over the visible and near-infrared spectral ranges. The emission, excitation, and absorption spectra were measured over a broad temperature range. The absolute luminescence quantum yield was estimated by comparing the luminescence with that of a neodymium-doped phosphate glass, for which the manufacturer gives a value of 0.4. The Judd-Ofelt analysis was applied to both materials, and transition rates, branching ratios, and quantum efficiencies were calculated for all the observed bands. Good agreement was obtained between theory and experiment.

Application of spark plasma sintering for fabricating Nd-Fe-B composite

NASA Astrophysics Data System (ADS)

Sivkov, A. A.; Ivashutenko, A. S.; Lomakina, A. A.

2015-10-01

Constant magnets are applied in such fields as electric equipment and electric generators with fixed rotor. Rare earth metal neodymium is well known as promising material. Production of magnets by sintering three elements (neodymium, iron and boron) is one the most promising methods. But there are difficulties in choosing the right temperature for sintering and further processing. Structure and properties of the product, consisted of rare earth metals, was analyzed. X-ray analysis of the resulting product and the finished constant magnet was performed. Vickers microhardness was obtained.

Boride Formation Induced by pcBN Tool Wear in Friction-Stir-Welded Stainless Steels

NASA Astrophysics Data System (ADS)

Park, Seung Hwan C.; Sato, Yutaka S.; Kokawa, Hiroyuki; Okamoto, Kazutaka; Hirano, Satoshi; Inagaki, Masahisa

2009-03-01

The wear of polycrystalline cubic boron nitride (pcBN) tool and its effect on second phase formation were investigated in stainless steel friction-stir (FS) welds. The nitrogen content and the flow stress were analyzed in these welds to examine pcBN tool wear. The nitrogen content in stir zone (SZ) was found to be higher in the austenitic stainless steel FS welds than in the ferritic and duplex stainless steel welds. The flow stress of austenitic stainless steels was almost 1.5 times larger than that of ferritic and duplex stainless steels. These results suggest that the higher flow stress causes the severe tool wear in austenitic stainless steels, which results in greater nitrogen pickup in austenitic stainless steel FS welds. From the microstructural observation, a possibility was suggested that Cr-rich borides with a crystallographic structure of Cr2B and Cr5B3 formed through the reaction between the increased boron and nitrogen and the matrix during FS welding (FSW).

Transition metal carbides, nitrides and borides, and their oxygen containing analogs useful as water gas shift catalysts

DOEpatents

Thompson, Levi T.; Patt, Jeremy; Moon, Dong Ju; Phillips, Cory

2003-09-23

Mono- and bimetallic transition metal carbides, nitrides and borides, and their oxygen containing analogs (e.g. oxycarbides) for use as water gas shift catalysts are described. In a preferred embodiment, the catalysts have the general formula of M1.sub.A M2.sub.B Z.sub.C O.sub.D, wherein M1 is selected from the group consisting of Mo, W, and combinations thereof; M2 is selected from the group consisting of Fe, Ni, Cu, Co, and combinations thereof; Z is selected from the group consisting of carbon, nitrogen, boron, and combinations thereof; A is an integer; B is 0 or an integer greater than 0; C is an integer; O is oxygen; and D is 0 or an integer greater than 0. The catalysts exhibit good reactivity, stability, and sulfur tolerance, as compared to conventional water shift gas catalysts. These catalysts hold promise for use in conjunction with proton exchange membrane fuel cell powered systems.

Ultra High Temperature Ceramics' Processing Routes and Microstructures Compared

NASA Technical Reports Server (NTRS)

Gusman, Michael; Stackpoole, Mairead; Johnson, Sylvia; Gasch, Matt; Lau, Kai-Hung; Sanjurjo, Angel

2009-01-01

Ultra High Temperature Ceramics (UHTCs), such as HfB2 and ZrB2 composites containing SiC, are known to have good thermal shock resistance and high thermal conductivity at elevated temperatures. These UHTCs have been proposed for a number of structural applications in hypersonic vehicles, nozzles, and sharp leading edges. NASA Ames is working on controlling UHTC properties (especially, mechanical properties, thermal conductivity, and oxidation resistance) through processing, composition, and microstructure. In addition to using traditional methods of combining additives to boride powders, we are preparing UHTCs using coat ing powders to produce both borides and additives. These coatings and additions to the powders are used to manipulate and control grain-boundary composition and second- and third-phase variations within the UHTCs. Controlling the composition of high temperature oxidation by-products is also an important consideration. The powders are consolidated by hot-pressing or field-assisted sintering (FAS). Comparisons of microstructures and hardness data will be presented.

A superconducting battery material: Lithium gold boride (LiAu3B)

NASA Astrophysics Data System (ADS)

Aydin, Sezgin; Şimşek, Mehmet

2018-04-01

The superconducting and potential cathode material properties of ternary boride of LiAu3B have been investigated by density functional first principles. The Li-concentration effects on the actual electronic and structural properties, namely the properties of LixAu9B3 (x = 0, 1, 2) sub-systems are studied. It is remarkably shown that the existence of Li-atoms has no considerable effect on the structural properties of Au-B skeleton in LiAu3B. Then, it can be offered as a potential cathode material for Li-ion batteries with the very small volume deviation of 0.42%, and the suitable average open circuit voltage of ∼1.30 V. Furthermore, the vibrational and superconducting properties such as electron-phonon coupling constant (λ) and critical temperature (Tc) of LiAu3B are studied. The calculated results suggest that LiAu3B should be a superconductor with Tc ∼5.8 K, also.

Twenty-Eight-Day Repeated Inhalation Toxicity Study of Nano-Sized Neodymium Oxide in Male Sprague-Dawley Rats

PubMed Central

Kim, Yong-Soon; Lim, Cheol-Hong; Shin, Seo-Ho; Kim, Jong-Choon

2017-01-01

Neodymium is a future-oriented material due to its unique properties, and its use is increasing in various industrial fields worldwide. However, the toxicity caused by repeated exposure to this metal has not been studied in detail thus far. The present study was carried out to investigate the potential inhalation toxicity of nano-sized neodymium oxide (Nd2O3) following a 28-day repeated inhalation exposure in male Sprague-Dawley rats. Male rats were exposed to nano-sized Nd2O3-containing aerosols via a nose-only inhalation system at doses of 0 mg/m3, 0.5 mg/m3, 2.5 mg/m3, and 10 mg/m3 for 6 hr/day, 5 days/week over a 28-day period, followed by a 28-day recovery period. During the experimental period, clinical signs, body weight, hematologic parameters, serum biochemical parameters, necropsy findings, organ weight, and histopathological findings were examined; neodymium distribution in the major organs and blood, bronchoalveolar lavage fluid (BALF), and oxidative stress in lung tissues were analyzed. Most of the neodymium was found to be deposited in lung tissues, showing a dose-dependent relationship. Infiltration of inflammatory cells and pulmonary alveolar proteinosis (PAP) were the main observations of lung histopathology. Infiltration of inflammatory cells was observed in the 2.5 mg/m3 and higher dose treatment groups. PAP was observed in all treatment groups accompanied by an increase in lung weight, but was observed to a lesser extent in the 0.5 mg/m3 treatment group. In BALF analysis, total cell counts, including macrophages and neutrophils, lactate dehydrogenase, albumin, interleukin-6, and tumor necrosis factor-alpha, increased significantly in all treatment groups. After a 4-week recovery period, these changes were generally reversed in the 0.5 mg/m3 group, but were exacerbated in the 10 mg/m3 group. The lowest-observed-adverse-effect concentration of nano-sized Nd2O3 was determined to be 0.5 mg/m3, and the target organ was determined to be the lung, under the present experimental conditions in male rats. PMID:28744356

High surface area neodymium phosphate nano particles by modified aqueous sol-gel method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sankar, Sasidharan; Warrier, Krishna Gopakumar, E-mail: wwarrierkgk@yahoo.co.in; Komban, Rajesh

2011-12-15

Graphical abstract: Synthesis of nano rod shaped neodymium phosphate particles with specific surface area as high as 107 m{sup 2} g{sup -1} and particles could be compacted and sintered at as low as 1300 Degree-Sign C to a density of 98.5% (theoretical) with an average grain size of {approx}1 {mu}m. Highlights: Black-Right-Pointing-Pointer Nano size neodymium phosphate is synthesized and characterized using a novel modified aqueous sol gel process. Black-Right-Pointing-Pointer Specific surface area above 100 m{sup 2} g{sup -1} achieved without the addition of any complexing agents. Black-Right-Pointing-Pointer High sintered density reported than the density obtained for powder synthesized through conventionalmore » solid state reaction. Black-Right-Pointing-Pointer The particles are nano sized and have rod shape morphology and are retained at higher temperatures. Black-Right-Pointing-Pointer An average grain size of {approx}1 {mu}m obtained for sintered NdPO{sub 4} after thermal etching at 1400 Degree-Sign C. -- Abstract: Synthesis of nano rod shaped neodymium phosphate (NdPO{sub 4}) particles with specific surface area as high as 107 m{sup 2}g{sup -1} and an average length of 50 nm with aspect ratio 5 was achieved using modified sol gel method. Crystallite size calculated from the X-ray diffraction data by applying Scherer equation was 5 nm for the precursor gel after calcination at 400 Degree-Sign C. NdPO{sub 4} was first precipitated from neodymium nitrate solution using phosphoric acid followed by peptization using dilute nitric acid and further gelation in ammonia atmosphere. The calcined gel powders were further characterized by surface area (Brunauer-Emmet-Teller nitrogen adsorption analysis), Transmission electron microscopy, scanning electron microscopy, UV-vis and FT-IR analysis. Transmission electron microscopy confirms the formation of rod like morphology from the sol, gel and the calcined particles in nano size range. These particles could be compacted and sintered at as low as 1300 Degree-Sign C to a density of 98.5% (theoretical) with an average grain size of {approx}1 {mu}m.« less

The Nature of the Microstructure and Interface Boundary Formation in Directionally Solidified Ceramic Boride Composites

DTIC Science & Technology

2011-05-01

failure resistance, which results from their different microplasticity (microbrittleness) and relaxation ability. In order to evaluate the... microplasticity (microbrittleness) in the series of isomorphic hexaborides produced by zone melting we have plotted a number of statistical curves that show

Ultracapacitor current collector

DOEpatents

Jerabek, Elihu Calfin; Mikkor, Mati

2001-10-16

An ultracapacitor having two solid, nonporous current collectors, two porous electrodes separating the collectors, a porous separator between the electrodes and an electrolyte occupying the pores in the electrodes and separator. At least one of the current collectors comprises a conductive metal substrate coated with a metal nitride, carbide or boride coating.

Characterisation of Nd2O3 thick gate dielectric for silicon

NASA Astrophysics Data System (ADS)

Dakhel, A. A.

2004-03-01

Thin neodymium films were prepared by the reactive synthesis method on Si (P) substrates to form MOS devices. The oxide films were characterised by UV absorption spectroscopy, X-ray fluorescence (EDXRF) and X-ray diffraction (XRD). The ac conductance and capacitance of the devices were studied as a function of frequency in the range 100 Hz-100 kHz, of temperature in the range 293-473 K and of gate voltage. It was proved that a suitable formalism to explain the frequency dependence of the ac conductivity and capacitance of the insulator is controlled by a universal power law based on the relaxation processes of the hopping or tunnelling of the current carriers between equilibrium sites. The temperature dependence of the ac conductance at the accumulation state shows a small activation energy of about 0.07 eV for a MOS device with amorphous neodymium oxide. The temperature dependence of the accumulation capacitance for a MOS structure with crystalline neodymium oxide shows a maximum at about 390 K; such a maximum was not observed for the structure with amorphous neodymium oxide. The method of capacitance-gate voltage (C-Vg) measurements was used to investigate the effect of annealing in air and in vacuum on the surface density of states (Nss) at the insulator/semiconductor (I/S) interface. It was concluded that the density of surface states in the mid-gap increases by about five times while the density of the trapped charges in the oxide layer decreases by about eight times when the oxide crystallises into a polycrystalline structure.

A contactless positioning system for monitoring discontinuities in three dimensions with geological and geotechnical applications

NASA Astrophysics Data System (ADS)

Rinaldi-Montes, Natalia; Rowberry, Matt; Frontera, Carlos; BaroÅ, Ivo; Garcés, Javier; Blahůt, Jan; Pérez-López, Raúl; Pennos, Christos; Martí, Xavi

2017-07-01

In this paper, a contactless positioning system is presented which has been designed to monitor the kinematic behavior of mechanical discontinuities in three dimensions. The positioning system comprises a neodymium magnet, fixed on one side of a discontinuity, and a magnetoresistive sensing array, fixed on the opposing side. Each of the anisotropic magnetoresistive sensors in the sensing array records the magnetic field along three orthogonal directions. The positioning system intrinsically generates compact data packages which are transmitted effectively using a range of standard wireless telecommunication technologies. These data are then modeled using a global least squares fitting procedure in which the adjustable parameters are represented by the position and orientation of the neodymium magnet. The instrumental resolution of the positioning system can be tuned depending on the strength of the magnetic field generated by the neodymium magnet and the distance between the neodymium magnet and the magnetoresistive sensing array. For a typical installation, the displacement resolution is shown to be circa 10 μm while the rotation resolution is circa 0.1°. The first permanently deployed positioning system was established in June 2016 to monitor the behavior of an N-S trending fault located at the contact between the eastern Alps and the Vienna Basin. The robust design of the positioning system is demonstrated by the fact that no interruptions in the broadcasted data streams have occurred since its installation. It has a range of potential applications in many areas of basic and applied research including geology, geotechnical engineering, and structural health monitoring.

Electrochemical extraction of neodymium by co-reduction with aluminum in LiCl-KCl molten salt

NASA Astrophysics Data System (ADS)

Yan, Yong-De; Xu, Yan-Lu; Zhang, Mi-Lin; Xue, Yun; Han, Wei; Huang, Ying; Chen, Qiong; Zhang, Zhi-Jian

2013-02-01

The electrochemical behavior of Nd(III) ions in LiCl-KCl and LiCl-KCl-AlCl3 melts on a Mo electrode at 723 K was studied by various electrochemical techniques. The results showed that Nd(III) ions are reduced to Nd(0) through two consecutive steps, and the underpotential deposition of neodymium on pre-deposited Al electrode formed two kinds of Al-Nd intermetallic compounds in LiCl-KCl-AlCl3 solutions. The electrochemical extraction of neodymium was carried out in LiCl-KCl-AlCl3 melts on a Mo electrode at 873 K by potentiostatic and galvanostatic electrolysis. The extraction efficiency was 99.25% after potentiostatic electrolysis for 30 h. Al-Li-Nd bulk alloy was obtained by galvanostatic electrolysis. X-ray diffraction (XRD) suggested that Al2Nd and Al3Nd phases were formed in Al-Li-Nd alloy. The microstructure and micro-zone chemical analysis of Al-Li-Nd alloy were characterized by scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS), respectively.

Effect of the addition of low rare earth elements (lanthanum, neodymium, cerium) on the biodegradation and biocompatibility of magnesium.

PubMed

Willbold, Elmar; Gu, Xuenan; Albert, Devon; Kalla, Katharina; Bobe, Katharina; Brauneis, Maria; Janning, Carla; Nellesen, Jens; Czayka, Wolfgang; Tillmann, Wolfgang; Zheng, Yufeng; Witte, Frank

2015-01-01

Rare earth elements are promising alloying element candidates for magnesium alloys used as biodegradable devices in biomedical applications. Rare earth elements have significant effects on the high temperature strength as well as the creep resistance of alloys and they improve magnesium corrosion resistance. We focused on lanthanum, neodymium and cerium to produce magnesium alloys with commonly used rare earth element concentrations. We showed that low concentrations of rare earth elements do not promote bone growth inside a 750 μm broad area around the implant. However, increased bone growth was observed at a greater distance from the degrading alloys. Clinically and histologically, the alloys and their corrosion products caused no systematic or local cytotoxicological effects. Using microtomography and in vitro experiments, we could show that the magnesium-rare earth element alloys showed low corrosion rates, both in in vitro and in vivo. The lanthanum- and cerium-containing alloys degraded at comparable rates, whereas the neodymium-containing alloy showed the lowest corrosion rates. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Pressed boride cathodes

NASA Technical Reports Server (NTRS)

Wolski, W.

1985-01-01

Results of experimental studies of emission cathodes made from lanthanum, yttrium, and gadolinium hexaborides are presented. Maximum thermal emission was obtained from lanthanum hexaboride electrodes. The hexaboride cathodes operated stably under conditions of large current density power draw, at high voltages and poor vacuum. A microtron electron gun with a lanthanum hexaboride cathode is described.

Thermophysical and Electronic Properties Information Analysis Center (TEPIAC): A Continuing Systematic Program on Tables of Thermophysical and Electronic Properties of Materials.

DTIC Science & Technology

1977-02-01

oxides and their mixtures, arsenides, borides, bromides , carbides , chlorides , fluoride s, nitride s, phosphides, silicides , sulfides , tellurides...ivity of alkali elements (lithium , sodium , potassium , rubi- dium , ces ium , and francium) and contains recomme nded reference values generated

Molecular Modeling of High-Temperature Oxidation of Refractory Borides

DTIC Science & Technology

2008-02-01

generate the classical potential, we adopt the van Beest , Kramer and van Santen (BKS) parameterization for Si-O interactions, but fit B-O and Si-B...seminar at Department of Aerospace and Mechanical Engineering, University of Notre Dame, March 20, 2007. 6 Los Alamos National Lab Physics & Theoretical

Neodymium-doped phosphate fiber lasers with an all-solid microstructured inner cladding.

PubMed

Zhang, Guang; Zhou, Qinling; Yu, Chunlei; Hu, Lili; Chen, Danping

2012-06-15

We report on high-power fiber lasers based on index-guiding, all-solid neodymium-doped (Nd-doped) phosphate photonic crystal fiber (PCF) with a hexagonal-shaped inner cladding. The optimum fiber laser with a 36 cm length active fiber, generated up to 7.92 W output power at 1053 nm, which benefited from a high absorption coefficient for pump power due to its noncircular inner cladding. The guiding properties of the all-solid PCF were also investigated. A stable mode with a donut-shaped profile and a power-dependent laser beam quality have been observed experimentally and analyzed.

High power 938 nanometer fiber laser and amplifier

DOEpatents

Dawson, Jay W [Livermore, CA; Liao, Zhi Ming [Pleasanton, CA; Beach, Raymond J [Livermore, CA; Drobshoff, Alexander D [Livermore, CA; Payne, Stephen A [Castro Valley, CA; Pennington, Deanna M [Livermore, CA; Hackenberg, Wolfgang [Munich, DE; Calia, Domenico Bonaccini [Garching, DE; Taylor, Luke [Montauban de Bretagne, FR

2006-05-02

An optical fiber amplifier includes a length of silica optical fiber having a core doped with neodymium, a first cladding and a second cladding each with succeeding lower refractive indices, where the first cladding diameter is less than 10 times the diameter of the core. The doping concentration of the neodymium is chosen so that the small signal absorption for 816 nm light traveling within the core is less than 15 dB/m above the other fiber losses. The amplifier is optically pumped with one laser into the fiber core and with another laser into the first cladding.

Neodymium glass laser with a phase conjugate mirror producing 220 J pulses at 0.02 Hz repetition rate.

PubMed

Kuzmin, A A; Khazanov, E A; Kulagin, O V; Shaykin, A A

2014-08-25

For pumping multipetawatt Ti:sapphire laser facilities we developed a compact repetitively pulsed laser based on neodymium phosphate glass with pulse energy of 220 J, pulse repetition rate of 0.02 Hz, beam diameter of 43 mm, aperture fill factor of 0.8, and FWHM pulse duration of 30 ns. The phase distortions of laser radiation were compensated by optical phase conjugation via stimulated Brillouin scattering. The depolarization was reduced to 0.4% using linear compensation methods. The beam quality was 2.5 x diffraction limit (150 µrad).

Liquid-liquid extraction of neodymium(III) by dialkylphosphate ionic liquids from acidic medium: the importance of the ionic liquid cation.

PubMed

Rout, Alok; Kotlarska, Justyna; Dehaen, Wim; Binnemans, Koen

2013-10-21

The ionic liquids 1-hexyl-3-methylimidazolium bis(2-ethylhexyl)phosphate, [C6mim][DEHP], 1-hexyl-1-methylpyrrolidinium bis(2-ethylhexyl)phosphate, [C6mpyr][DEHP], and tetrabutylammonium bis(2-ethylhexyl)phosphate, [N4444][DEHP], were prepared and characterized using (1)H and (13)C NMR spectroscopy. The extraction behavior of neodymium(iii) from nitrate medium by these ionic liquids, diluted with the room temperature ionic liquids 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C6mim][NTf2], 1-hexyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [C6mpyr][NTf2], and tributylmethylammonium bis(trifluoromethylsulfonyl)imide, [N1444][NTf2], was studied. The distribution ratio of neodymium(iii) was measured as a function of various parameters, such as pH, concentration of the ionic liquid extractant, nature of diluents, concentration of ionic liquid cations and nitrate anions in the aqueous phase. The extraction behavior was compared with that obtained for a solution of the molecular extractant bis(2-ethylhexyl)phosphoric acid (DEHPA) in an ionic liquid diluent. The extraction of neodymium(iii) in the ionic liquids [C6mim][DEHP] and [C6mpyr][DEHP] showed markedly different extraction properties in comparison with that of the quaternary ammonium analogue [N4444][DEHP], especially concerning the pH dependence of the extraction process. These results show that the extraction process can be tuned by the selection of the ionic liquid cation. The extraction experiments also included the trivalent rare-earth ions lanthanum(iii), cerium(iii), praseodymium(iii), ytterbium(iii) and yttrium(iii). Studies of the stripping behavior and the reusability of the ionic liquids were carried out, which indicate that the ionic liquids can be reused with no loss in activity.

Lithotripsy of gallstones by means of a quality-switched giant-pulse neodymium:yttrium-aluminum-garnet laser. Basic in vitro studies using a highly flexible fiber system.

PubMed

Hochberger, J; Gruber, E; Wirtz, P; Dürr, U; Kolb, A; Zanger, U; Hahn, E G; Ell, C

1991-11-01

The quality-switched neodymium:yttrium-aluminum-garnet laser represents a new instrument for athermal fragmentation of gallstones by transformation of optical energy into mechanical energy in the form of shock waves via local plasma formation. A highly flexible 300-micron fiber transmission system was used in basic investigations to determine the influence of varying pulse repetition rates (5-30 Hz) and pulse energies (15 and 20 mJ) on shock wave intensity and stone fragmentation in vitro for 105 biliary calculi of known size and chemical composition. After performance of 1200 shock wave pressure measurements using polyvinylidenefluoride hydrophones, stone fragmentation was analyzed by determination of fragment removal rates (volume of fragments removed per fragmentation time), ablation rates (mean volume removed per laser pulse), and median fragment sizes for each laser setting. With the quality-switched neodymium:yttrium-aluminum-garnet laser system, all concrements could be reliably disintegrated into small fragments (median diameter, 0.7-1.7 mm). Compared with pure cholesterol stones, a significantly higher fragment removal rate was achieved in cholesterol stones containing 30% calcium phosphate (P = 0.039), in cholesterol stones containing 20% pigment (P = 0.015), and in pure pigment stones (P = 0.007). Fragment removal rates, local shock wave pressures, and median grain sizes were significantly higher at a pulse energy of 20 mJ than with 15 mJ. Shock wave pressures showed a distinct dependence on pulse repetition rates at 20 mJ, yet not at 15 mJ. Because there is no evident hazard of thermal damage to tissue using the quality-switched neodymium:yttrium-aluminum-garnet laser, it appears to be a promising device for nonsurgical biliary stone therapy.

Lithium Borides - High Energy Materials

DTIC Science & Technology

2000-02-28

1993. 99, 7983. (32) Pulay P.; Hamilton. T. P. J. Chem. Phys. 1988, 88. 4926 . (33) Frisch. M. J.: Trucks. G. W.; Schlegel. H. B.: Gill, P. M. W...25] P.V. Sudhakar, K. Lammertsma, J. Chem. Phys. 99 (1993) 7929. [26] M.J. van der Woerd, K. Lammertsma, B.J. Duke, H.F. Schaefer , III, J

Grain Refinement and Texture Mitigation in Low Boron Containing TiAl-Alloys

NASA Astrophysics Data System (ADS)

Hecht, Ulrike; Witusiewicz, Victor T.

2017-12-01

Controlling the grain size and texture of lamellar TiAl-alloys is essential for well-balanced creep and fatigue properties. Excellent refinement and texture mitigation are achieved in aluminum lean alloys by low boron additions of 0.2 at.%. This amount is sufficient to promote in situ formation of ultrafine borides during the last stages of body centered cubic (BCC) solidification. The borides subsequently serve as nucleation sites for hexagonal close packed (HCP) during the BCC-HCP phase transformation. Bridgman solidification experiments with alloy Ti-43Al-8Nb-0.2C-0.2B were performed under a different growth velocity, i.e., cooling rate, to evaluate the HCP grain size distribution and texture. For slow-to-moderate cooling rates, about 65% of HCP grains are randomly oriented, despite the pronounced texture of the parent BCC phase resulting from directional solidification. For high cooling rates, obtained by quenching, texture mitigation is less pronounced. Only 28% of the HCP grains are randomly oriented, the majority being crystallographic variants of the Burgers orientation relationship.

An XPS study of the adherence of refractory carbide, silicide, and boride RF-sputtered wear-resistant coatings. [X-ray Photoelectron Spectroscopy of steel surfaces

NASA Technical Reports Server (NTRS)

Brainard, W. A.; Wheeler, D. R.

1978-01-01

Radio frequency sputtering was used to deposit refractory carbide, silicide, and boride coatings on 440-C steel substrates. Both sputter etched and pre-oxidized substrates were used and the films were deposited with and without a substrate bias. The composition of the coatings was determined as a function of depth by X-ray photoelectron spectroscopy combined with argon ion etching. Friction and wear tests were conducted to evaluate coating adherence. In the interfacial region there was evidence that bias may produce a graded interface for some compounds. Biasing, while generally improving bulk film stoichiometry, can adversely affect adherence by removing interfacial oxide layers. Oxides of all film constituents except carbon and iron were present in all cases but the iron oxide coverage was only complete on the preoxidized substrates. The film and iron oxides were mixed in the MoSi2 and Mo2C films but layered in the Mo2B5 films. In the case of mixed oxides, preoxidation enhanced film adherence. In the layered case it did not.

Boronization and Carburization of Superplastic Stainless Steel and Titanium-Based Alloys

PubMed Central

Matsushita, Masafumi

2011-01-01

Bronization and carburization of fine-grain superplastic stainless steel is reviewed, and new experimental results for fine grain Ti88.5Al4.5V3Fe2Mo2 are reported. In superplastic duplex stainless steel, the diffusion of carbon and boron is faster than in non-superplastic duplex stainless steel. Further, diffusion is activated by uniaxial compressive stress. Moreover, non-superplastic duplex stainless steel shows typical grain boundary diffusion; however, inner grain diffusion is confirmed in superplastic stainless steel. The presence of Fe and Cr carbides or borides is confirmed by X-ray diffraction, which indicates that the diffused carbon and boron react with the Fe and Cr in superplastic stainless steel. The Vickers hardness of the carburized and boronized layers is similar to that achieved with other surface treatments such as electro-deposition. Diffusion of boron into the superplastic Ti88.5Al4.5V3Fe2Mo2 alloy was investigated. The hardness of the surface exposed to boron powder can be increased by annealing above the superplastic temperature. However, the Vickers hardness is lower than that of Ti boride. PMID:28824144

Nd and Sm isotopic composition of spent nuclear fuels from three material test reactors

DOE PAGES

Sharp, Nicholas; Ticknor, Brian W.; Bronikowski, Michael; ...

2016-11-17

Rare earth elements such as neodymium and samarium are ideal for probing the neutron environment that spent nuclear fuels are exposed to in nuclear reactors. The large number of stable isotopes can provide distinct isotopic signatures for differentiating the source material for nuclear forensic investigations. The rare-earth elements were isolated from the high activity fuel matrix via ion exchange chromatography in a shielded cell. The individual elements were then separated using cation exchange chromatography. In conclusion, the neodymium and samarium aliquots were analyzed via MC–ICP–MS, resulting in isotopic compositions with a precision of 0.01–0.3%.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walters, C.T.; Dulaney, J.L.; Campbell, B.E.

Demonstrations of operation of a compact neodymium glass laser with average output powers greater than 1 kW for several seconds are reported. The laser is based on the thermal inertia laser (TIL) concept wherein a neodymium-doped glass rod is pumped uniformly without cooling during a burst mode of laser operation. Design principles for TIL devices and scaling to 100 kW class lasers are discussed. Experimental results for a low repetition-rate proof-of-concept pulsed device (30 J, 0.2 Hz) and a high repetition-rate pulsed prototype (40 J, 36 Hz) are presented and compared to numerical solutions for the laser rate equations withmore » temperature dependent cross-sections.« less

Nd and Sm isotopic composition of spent nuclear fuels from three material test reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharp, Nicholas; Ticknor, Brian W.; Bronikowski, Michael

Rare earth elements such as neodymium and samarium are ideal for probing the neutron environment that spent nuclear fuels are exposed to in nuclear reactors. The large number of stable isotopes can provide distinct isotopic signatures for differentiating the source material for nuclear forensic investigations. The rare-earth elements were isolated from the high activity fuel matrix via ion exchange chromatography in a shielded cell. The individual elements were then separated using cation exchange chromatography. In conclusion, the neodymium and samarium aliquots were analyzed via MC–ICP–MS, resulting in isotopic compositions with a precision of 0.01–0.3%.

Re{sup 3+} : YAG laser ceramics: synthesis, optical properties and laser characteristics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bagayev, S N; Vatnik, S M; Vedin, I A

2015-05-31

Highly transparent yttrium aluminium garnet ceramics doped with holmium or ytterbium or neodymium are synthesised. The ceramics were made of a mixture of nanopowders synthesised by laser ablation. The structural and spectral characteristics of ceramics are studied. In the samples with holmium Ho{sup 3+} and neodymium Nd{sup 3+} ions, lasing was achieved with a slope efficiency of 40% and 35.3%, respectively; the maximum laser power exceeded 4 W. The internal absorption and scattering losses for 1% Nd : YAG ceramics are estimated to be 1.6 × 10{sup -2} cm{sup -1}. (extreme light fields and their applications)

An experimental technique to repair cracked teeth using calcium phosphate, melted by a laser beam: an in vitro evaluation.

PubMed

Levy, G C; Koubi, G F

1993-11-01

Using a neodymium: yttrium-aluminum-garnet laser beam to seal vertical root fracture lines with tricalcium phosphate paste represents an alternative treatment for cracked teeth with noted clinical results. This article describes a study of the permeability of molten crystals of hydroxyapatite in the dentin of a cracked root after crack lines have been filled with a preparation of tricalcium phosphate melted by a neodymium: yttrium-aluminum-garnet laser beam. The morphology of the sealed cracks was analyzed under a scanning electron microscope that showed a deep fusion of tricalcium phosphate along crack lines.

Gadolinium and didymium (praseodymium/neodymium) cations as capture agents in lightmicroscopical histochemistry of acid and alkaline phosphatase.

PubMed

Halbhuber, K J; Zimmermann, N

1987-01-01

In previous papers, cerium and lanthanum based methods for light-microscopical detection of acid and alkaline phosphatase activity were proposed. In this paper, the usefulness of other lanthanide cations such as gadolinium and praseodymium/neodymium cations as capture agents in phosphatase histochemistry is tested. It is evident that phosphate ions were sufficiently trapped by these cations. According to the lead and silver multistep procedures earlier described it is possible to visualize alkaline phosphatase activity in the brush borders of the intestine or kidney as well as acid phosphatase activity in the lysosomes. These methods can be recommended.

Electrochemistry and the mechanisms of nucleation and growth of neodymium during electroreduction from LiCl-KCl eutectic salts on Mo substrate

NASA Astrophysics Data System (ADS)

Tang, Hao; Pesic, Batric

2015-03-01

The electrochemical behavior of NdCl3 was studied on a Mo electrode in molten LiCl-KCl eutectic salts. The electroreduction of Nd(III)/Nd(0) involved two reaction steps, as confirmed by three different electrochemical techniques. In the first reaction step, Nd(III) is converted into soluble Nd(II), which undergoes further reduction into metallic Nd(0) in the second reaction step. The standard reaction rate constants for each reaction step were determined by Nicholson method. The rate constant values were used in Matsuda-Ayabe's criteria for testing the electrochemical reversibility. Accordingly, both reaction steps were quasi-reversible redox reactions. The nucleation mechanisms of neodymium metal deposited on a Mo substrate were predicted by using Scharifker-Hill model, and tested for the first time by scanning electron microscopy (SEM) studies of the electrode surface. The SEM studies confirmed that for the low initial concentration of NdCl3, neodymium nucleates and grows progressively, while for higher NdCl3 concentrations, the related mechanism is instantaneous. Both are governed by the aggregative growth mechanisms based on surface mobility of formed nanoclusters.

Lattice thermal expansion and solubility limits of neodymium-doped ceria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Jinhua, E-mail: jhzhang1212@126.com; State Key laboratory of Geological Process and Mineral Resources, China University of Geosciences, Wuhan 430074; Ke, Changming

2016-11-15

Nd{sub x}Ce{sub 1−x}O{sub 2−0.5x} (x=0–1.0) powders were prepared by reverse coprecipitation-calcination method and characterized by XRD. The crystal structure of product powders transformed from single fluorite structure to the complex of fluorite and C-type cubic structure, and finally to trigonal structure with the increase of x-value. An empirical equation simulating the lattice parameter of neodymium doped ceria was established based on the experimental data. The lattice parameters of the fluorite structure solid solutions increased with extensive adoption of Nd{sup 3+}, and the heating temperature going up. The average thermal expansion coefficients of neodymium doped ceria with fluorite structure are highermore » than 13.5×10{sup −6} °C{sup −1} from room temperature to 1200 °C. - Graphical abstract: The crystal structure of Nd{sub x}Ce{sub 1−x}O{sub 2−0.5x} (x=0–1.0) powders transformed from single fluorite structure to the complex of fluorite and C-type cubic structure, and finally to trigonal structure with the increase of x-value.« less

Global mining risk footprint of critical metals necessary for low-carbon technologies: the case of neodymium, cobalt, and platinum in Japan.

PubMed

Nansai, Keisuke; Nakajima, Kenichi; Kagawa, Shigemi; Kondo, Yasushi; Shigetomi, Yosuke; Suh, Sangwon

2015-02-17

Meeting the 2-degree global warming target requires wide adoption of low-carbon energy technologies. Many such technologies rely on the use of precious metals, however, increasing the dependence of national economies on these resources. Among such metals, those with supply security concerns are referred to as critical metals. Using the Policy Potential Index developed by the Fraser Institute, this study developed a new footprint indicator, the mining risk footprint (MRF), to quantify the mining risk directly and indirectly affecting a national economy through its consumption of critical metals. We formulated the MRF as a product of the material footprint (MF) of the consuming country and the mining risks of the countries where the materials are mined. A case study was conducted for the 2005 Japanese economy to determine the MF and MRF for three critical metals essential for emerging energy technologies: neodymium, cobalt and platinum. The results indicate that in 2005 the MFs generated by Japanese domestic final demand, that is, the consumption-based metal output of Japan, were 1.0 × 10(3) t for neodymium, 9.4 × 10(3) t for cobalt, and 2.1 × 10 t for platinum. Export demand contributes most to the MF, accounting for 3.0 × 10(3) t, 1.3 × 10(5) t, and 3.1 × 10 t, respectively. The MRFs of Japanese total final demand (domestic plus export) were calculated to be 1.7 × 10 points for neodymium, 4.5 × 10(-2) points for cobalt, and 5.6 points for platinum, implying that the Japanese economy is incurring a high mining risk through its use of neodymium. This country's MRFs are all dominated by export demand. The paper concludes by discussing the policy implications and future research directions for measuring the MFs and MRFs of critical metals. For countries poorly endowed with mineral resources, adopting low-carbon energy technologies may imply a shifting of risk from carbon resources to other natural resources, in particular critical metals, and a trade-off between increased mining risk and deployment of such technologies. Our analysis constitutes a first step toward quantifying and managing the risks associated with natural resource mining.

Pt-B System Revisited: Pt2B, a New Structure Type of Binary Borides. Ternary WAl12-Type Derivative Borides.

PubMed

Sologub, Oksana; Salamakha, Leonid; Rogl, Peter; Stöger, Berthold; Bauer, Ernst; Bernardi, Johannes; Giester, Gerald; Waas, Monika; Svagera, Robert

2015-11-16

On the basis of a detailed study applying X-ray single-crystal and powder diffraction, differential scanning calorimetry, and scanning electron microscopy analysis, it was possible to resolve existing uncertainties in the Pt-rich section (≥65 atom % Pt) of the binary Pt-B phase diagram above 600 °C. The formation of a unique structure has been observed for Pt2B [X-ray single-crystal data: space group C2/m, a = 1.62717(11) nm, b = 0.32788(2) nm, c = 0.44200(3) nm, β = 104.401(4)°, RF2 = 0.030]. Within the homogeneity range of "Pt3B", X-ray powder diffraction phase analysis prompted two structural modifications as a function of temperature. The crystal structure of "hT-Pt3B" complies with the hitherto reported structure of anti-MoS2 [space group P63/mmc, a = 0.279377(2) nm, c = 1.04895(1) nm, RF = 0.075, RI = 0.090]. The structure of the new "[Formula: see text]T-Pt3B" is still unknown. The formation of previously reported Pt∼4B has not been confirmed from binary samples. Exploration of the Pt-rich section of the Pt-Cu-B system at 600 °C revealed a new ternary compound, Pt12CuB6-y [X-ray single-crystal data: space group Im3̅, a = 0.75790(2) nm, y = 3, RF2 = 0.0129], which exhibits the filled WAl12-type structure accommodating boron in the interstitial trigonal-prismatic site 12e. The isotypic platinum-aluminum-boride was synthesized and studied. The solubility of copper in binary platinum borides has been found to attain ∼7 atom % Cu for Pt2B but to be insignificant for "[Formula: see text]T-Pt3B". The architecture of the new Pt2B structure combines puckered layers of boron-filled and empty [Pt6] octahedra (anti-CaCl2-type fragment) alternating along the x axis with a double layer of boron-semifilled [Pt6] trigonal prisms interbedded with a layer of empty tetrahedra and tetragonal pyramids (B-deficient α-T[Formula: see text]I fragment). Assuming boron vacancies ordering (space group R3), the Pt12CuB6-y structure exhibits serpentine-like columns of edge-connected boron-filled [Pt6] trigonal prisms running infinitely along the z axis and embedding the icosahedrally coordinated Cu atom. Pt2B, (Pt1-yCuy)2B (y = 0.045), and Pt12CuB6-y (y = 3) behave metallically, as revealed by temperature-dependent electrical resistivity measurements.

Solid State Research, 1973:2.

DTIC Science & Technology

MERCURY COMPOUNDS, CADMIUM COMPOUNDS, TELLURIDES, NEODYMIUM COMPOUNDS, PHOSPHATES , ELECTRON TRANSITIONS, INFRARED OPTICAL MATERIALS, CRYSTAL GROWTH, MAGNESIUM OXIDES, PHOSPHORESCENT MATERIALS, SEMICONDUCTOR DIODES, MICROELECTRONICS

Eastern Indian 3800-million-year-old crust and early mantle differentiation

USGS Publications Warehouse

Basu, A.R.; Ray, S.L.; Saha, A.K.; Sarkar, S.N.

1981-01-01

Samarium-neodymium data for nine granitic and tonalite gneisses occurring as remnants within the Singhbhum granite batholith in eastern India define an isochron of age 3775 ?? 89 ?? 106 years with an initial 143Nd/144Nd ratio of 0.50798 ?? 0.00007. This age contrasts with the rubidium-strontium age of 3200 ?? 106 years for the same suite of rocks. On the basis of the new samarium-neodynium data, field data, and petrologic data, a scheme of evolution is proposed for the Archean crust in eastern India. The isotopic data provide evidence that parts of the earth's mantle were already differentiated with respect to the chondritic samarium-neodymium ratio 3800 ?? 106 years ago.

Solid-state reaction kinetics of neodymium doped magnesium hydrogen phosphate system

NASA Astrophysics Data System (ADS)

Gupta, Rashmi; Slathia, Goldy; Bamzai, K. K.

2018-05-01

Neodymium doped magnesium hydrogen phosphate (NdMHP) crystals were grown by using gel encapsulation technique. Structural characterization of the grown crystals has been carried out by single crystal X-ray diffraction (XRD) and it revealed that NdMHP crystals crystallize in orthorhombic crystal system with space group Pbca. Kinetics of the decomposition of the grown crystals has been studied by non-isothermal analysis. The estimation of decomposition temperatures and weight loss has been made from the thermogravimetric/differential thermo analytical (TG/DTA) in conjuncture with DSC studies. The various steps involved in the thermal decomposition of the material have been analysed using Horowitz-Metzger, Coats-Redfern and Piloyan-Novikova equations for evaluating various kinetic parameters.

Prediction of the new efficient permanent magnet SmCoNiFe3

NASA Astrophysics Data System (ADS)

Söderlind, P.; Landa, A.; Locht, I. L. M.; Åberg, D.; Kvashnin, Y.; Pereiro, M.; Däne, M.; Turchi, P. E. A.; Antropov, V. P.; Eriksson, O.

2017-09-01

We propose a new efficient permanent magnet, SmCoNiFe3, which is a development of the well-known SmCo5 prototype. More modern neodymium magnets of the Nd-Fe-B type have an advantage over SmCo5 because of their greater maximum energy products due to their iron-rich stoichiometry. Our new magnet, however, removes most of this disadvantage of SmCo5 while preserving its superior high-temperature efficiency over the neodymium magnets. We show by means of first-principles electronic-structure calculations that SmCoNiFe3 has very favorable magnetic properties and could therefore potentially replace SmCo5 or Nd-Fe-B types in various applications.

Multiple Doped Erbium Glasses,

DTIC Science & Technology

GLASS, LASERS, ERBIUM, ERBIUM COMPOUNDS, DOPING, OXIDES, OPTIMIZATION, ATOMIC ENERGY LEVELS, PHOSPHATES , YTTERBIUM COMPOUNDS, NEODYMIUM COMPOUNDS, OPTICAL PUMPING, FLUORESCENCE, LIFE EXPECTANCY(SERVICE LIFE), BAND SPECTRA.

Nd/TiO2 Anatase-Brookite Photocatalysts for Photocatalytic Decomposition of Methanol.

PubMed

Kočí, Kamila; Troppová, Ivana; Reli, Martin; Matějová, Lenka; Edelmannová, Miroslava; Drobná, Helena; Dubnová, Lada; Rokicińska, Anna; Kuśtrowski, Piotr; Čapek, Libor

2018-01-01

Neodymium enriched TiO 2 anatase-brookite powders were prepared by unconventional method via using pressurized hot fluids for TiO 2 crystallization and purification. The photocatalysts were tested in the CH 3 OH photocatalytic decomposition and they were characterized with respect to the textural (nitrogen adsorption), structural (XRD, XPS, and Raman spectroscopies), chemical (XRF), and optical (DR UV-Vis spectroscopy) and photoelectrochemical measurement. All prepared materials were nanocrystalline, had biphasic (anatase- brookite) structure and relatively large specific surface area (125 m 2 .g -1 ). The research work indicates that the doping of neodymium on TiO 2 photocatalysts significantly enhances the efficiency of photocatalytic reaction. The photocatalytic activity increased with increasing portion of hydroxyl oxygen to the total amount of oxygen species. It was ascertained that the optimal amount of 1 wt% Nd in TiO 2 accomplished the increasing of hydrogen production by 70% in comparison with pure TiO 2 . The neodymium doped on the titanium dioxide act as sites with accumulation of electrons. The higher efficiency of photocatalytic process was achieved due to improved electron-hole separation on the modified TiO 2 photocatalysts. This result was confirmed by electrochemical measurements, the most active photocatalysts proved the highest photocurrent responses.

Nd/TiO2 Anatase-Brookite Photocatalysts for Photocatalytic Decomposition of Methanol

PubMed Central

Kočí, Kamila; Troppová, Ivana; Reli, Martin; Matějová, Lenka; Edelmannová, Miroslava; Drobná, Helena; Dubnová, Lada; Rokicińska, Anna; Kuśtrowski, Piotr; Čapek, Libor

2018-01-01

Neodymium enriched TiO2 anatase-brookite powders were prepared by unconventional method via using pressurized hot fluids for TiO2 crystallization and purification. The photocatalysts were tested in the CH3OH photocatalytic decomposition and they were characterized with respect to the textural (nitrogen adsorption), structural (XRD, XPS, and Raman spectroscopies), chemical (XRF), and optical (DR UV-Vis spectroscopy) and photoelectrochemical measurement. All prepared materials were nanocrystalline, had biphasic (anatase- brookite) structure and relatively large specific surface area (125 m2.g−1). The research work indicates that the doping of neodymium on TiO2 photocatalysts significantly enhances the efficiency of photocatalytic reaction. The photocatalytic activity increased with increasing portion of hydroxyl oxygen to the total amount of oxygen species. It was ascertained that the optimal amount of 1 wt% Nd in TiO2 accomplished the increasing of hydrogen production by 70% in comparison with pure TiO2. The neodymium doped on the titanium dioxide act as sites with accumulation of electrons. The higher efficiency of photocatalytic process was achieved due to improved electron-hole separation on the modified TiO2 photocatalysts. This result was confirmed by electrochemical measurements, the most active photocatalysts proved the highest photocurrent responses. PMID:29552558

PREFACE: The 16th International Symposium on Boron, Borides and Related Materials (ISBB 2008)

NASA Astrophysics Data System (ADS)

Tanaka, Takaho

2009-07-01

This volume of Journal of Physics: Conference Series contains invited and contributed peer-reviewed papers that were presented at the 16th International Symposium on Boron, Borides and Related Materials (ISBB 2008), which was held on 7-12 September 2008, at Kunibiki Messe, Matsue, Japan. This triennial symposium has a half-century long history starting from the 1st meeting in 1959 at Asbury Park, New Jersey. We were very pleased to organize ISBB 2008, which gathered chemists, physicists, materials scientists as well as diamond and high-pressure researchers. This meeting had a strong background in the boron-related Japanese research history, which includes the discovery of superconductivity in MgB2 and development of Nd-Fe-B hard magnets and of YB66 soft X-ray monochromator. The scope of ISBB 2008 spans both basic and applied interdisciplinary research that is centered on boron, borides and related materials, and the collection of articles defines the state of the art in research on these materials. The topics are centered on: 1. Preparation of new materials (single crystals, thin films, nanostructures, ceramics, etc) under normal or extreme conditions. 2. Crystal structure and chemical bonding (new crystal structures, nonstoichiometry, defects, clusters, quantum-chemical calculations). 3. Physical and chemical properties (band structure, phonon spectra, superconductivity; optical, electrical, magnetic, emissive, mechanical properties; phase diagrams, thermodynamics, catalytic activity, etc) in a wide range of temperatures and pressures. 4. Applications and prospects (thermoelectric converters, composites, ceramics, coatings, etc) There were a few discoveries of new materials, such as nanomaterials, and developments in applications. Many contributions were related to 4f heavy Fermion systems of rare-earth borides. Exotic mechanisms of magnetism and Kondo effects have been discussed, which may indicate another direction of development of boride. Two special sessions, 'Boron chemistry' and 'Superconductivity', were also held at the symposium. The session on Boron chemistry was planned to honor the scientific work in boron chemistry of Professor J Bauer on the occasion of his retirement. Many recent results were discussed in the session, and Professor Bauer himself introduced novel rare-earth-boron-carbon compounds RE10B7C10 (RE = Gd - Er) in his lecture. In the latter session, on the basis of recent discoveries of superconductivity in MgB2 and in β-boron under high pressure, the superconductivity of boron and related materials was discussed and the superconductivity of boron-doped diamond was also addressed. More than 120 participants from 16 countries attended the ISBB 2008, and active presentations (22 invited, 33 oral and 68 posters) and discussions suggest that research on boron and borides is entering a new phase of development. This volume contains 46 articles from 52 submitted manuscripts. The reviewers were invited not only from symposium participants but also from specialists worldwide, and they did a great job of evaluating and commenting on the submitted manuscripts to maintain the highest quality standard of this volume. Recent discoveries of superconductivity in boron under high pressure, synthesis of a new allotrope of boron and of various boron and boride nanostructures will lead this highly interdisciplinary field of science, which will further grow and gain attention in terms of both basic and applied research. In this context, we are very much looking forward to the next symposium, which will be held in Istanbul, Turkey, in 2011, organized by Professor Onuralp Yucel, Istanbul Technical University. Turkey currently has the world highest share of borate production and is expected to be involved more in boron-related research. Acknowledgements We gratefully acknowledge the style improvement by Dr K Iakoubovskii, and sincerely thank Shimane Prefecture and Matsue City for their financial support. The symposium was also supported by Tokyo University of Science, Suwa and foundations including, the Kajima Foundation, Foundation for Promotion of Material Science and Technology of Japan and Nippon Sheet Glass Foundation for Materials Science and Engineering, as well as companies including JFE Steel Corporation, Shincron Co, Ltd, Toyo Kohan Co, Ltd, Fukuda Metal Foil and Powder Co, Ltd, Japan New Metals Co, Ltd, H C Starck Ltd and Fritsch Japan Co, Ltd. Editors Chair Takaho Tanaka (National Institute for Materials Science, Japan) Vice chairs Koun Shirai (Osaka University, Japan) Kaoru Kimura (The University of Tokyo, Japan) Ken-ichi Takagi (Tokyo City University, Japan) Touetsu Shishido (Tohoku University, Japan) Shigeru Okada (Kokushikan University) Hideaki Itoh (Nagoya University,Japan) Katsumitsu Nakamura (Nihon University, Japan) Organizing committee of ISBB 2008 K Takagi Chairman (Tokyo City University) T Tanaka Program Committee Chairman (National Institute for Materials Science) K Kimura Secretary (The University of Tokyo) J Akimitsu (Aoyama University)K Shirai (Osaka University) H Itoh (Nagoya University)T Shishido (Tohoku University) K Nakamura (Nihon University)K Soga (Tokyo University of Science) K Nishiyama (Tokyo University of Science, Suwa)M Takeda (Nagaoka University of Technology) S Okada (Kokushikan University)Y Yamazaki (Toyo Kohan Co, Ltd) International Scientific Committee 0f ISBB (2008-2011) K Takagi Chairman (Japan) B Albert (Germany) J-F Halet (France) M Takeda (Japan) M Antadze (Georgia) H Hillebrecht (Germany) T Tanaka (Japan) J Bauer (France) W Jung (Germany) R Telle (Germany) I Boustani (Germany) K Kimura (Japan) M Trenary (USA) D Emin (USA) T Mori (Japan) O Tsagareishvili (Georgia) M Engler (Germany) P D Ownby (USA) H Werheit (Germany) N Frage (Israel) P Rogl (Austria) G Will (Germany) Yu Grin (Germany) S Shalamberidze (Georgia) O Yucel (Turkey) V N Gurin (Russia) N Shitsevalova (Ukraine) G Zhang (China)

Thermal emission property of solid solution Gd{sub 1-x}Nd{sub x}B{sub 6} (x=0, 0.6, 0.8)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xing Zhang, Jiu; Hong Bao, Li; Lin Zhou, Shen, E-mail: zjiuxing@bjut.edu.cn, E-mail: Baolihong_10@yahoo.com.cn, E-mail: zhoushenlin@emails.bjut.edu.cn

2011-07-01

In this paper, to further explore the excellent emission properties of rare earth boride cathode, herein we present the synthesis, characterization and properties of polycrystalline Nd{sub 1-x}Gd{sub x}B{sub 6} (x = 0, 0.6, 0.8) bulk via arc plasma and reactive SPS. (author)

Process research into metallic pipe wear of hot chamber die casting machines and methods ofincreasing wear resistance

NASA Astrophysics Data System (ADS)

Mukhametzyanova, G. F.; Kolesnikov, MS; Mukhametzyanov, I. R.; Astatshenko, V. I.

2017-09-01

The kinetics and reasons for metallic pipe wear of hot chamberzinc alloy die casting machines are established.Increasing metallic pipe wear components wear resistance is being achieved by means of die steelДИ - 22 with electroslag remelting modification and electron-beamremelting modification and after the processes of nitriding and boriding besides.

Nb2OsB2, with a new twofold superstructure of the U3Si2 type: Synthesis, crystal chemistry and chemical bonding

NASA Astrophysics Data System (ADS)

Mbarki, Mohammed; Touzani, Rachid St.; Fokwa, Boniface P. T.

2013-07-01

The new ternary metal-rich boride, Nb2OsB2, was synthesized by arc-melting the elements in a water-cooled copper crucible under an argon atmosphere. The compound was characterized from single-crystal X-ray data and EDX measurements. It crystallizes as a new superstructure (space group P4/mnc, no. 128) of the tetragonal U3Si2-structure type with lattice parameters a=5.922(1) Å and c=6.879(2) Å. All of the B atoms are involved in B2 dumbbells with B-B distances of 1.89(4) Å. Structure relaxation using VASP (Vienna ab intio Simulation Package) has confirmed the space group and the lattice parameters. According to electronic structure calculations (TB-LMTO-ASA), the homoatomic B-B interactions are optimized and very strong, but relatively strong heteroatomic Os-B, Nb-B and Nb-Os bonds are also found: These interactions, which together build a three-dimensional network, are mainly responsible for the structural stability of this new phase. The density of state at the Fermi level predicts metallic behavior, as expected, from this metal-rich boride.

The use of surface layer with boron in friction pairs lubricated by engine oils

NASA Astrophysics Data System (ADS)

Szczypiński-Sala, W.; Lubas, J.

2016-09-01

The aim of the present work is to determine the influence of surface layers with boron and engine oil on the processes of friction and wear in friction pairs. The ring samples with borided surface layer cooperated under test conditions with counterparts made with CuPb30 and AlSn20 bearing alloys. During the tests, the friction pairs were lubricated with 15W/40 Lotos mineral oil and 5W/40 Lotos synthetic oil. The lubrication of friction area with Lotos mineral oil causes the reduction of the friction force, the temperature in the friction area and the wear of the bearing alloys under study, whereas the lubrication with Lotos synthetic oil reduces the changes in the geometrical structure of the cooperating friction pair elements. Lubrication of the friction area in the start-up phase of the friction pair by mineral oil causes faster stabilization of the friction conditions in the contact area than in the cause of lubrication of the friction pair by synthetic oil. The intensity of wear of the AlSn20 bearing alloy cooperating with the borided surface layer is three times smaller than the intensity of use of the CuPb30 alloy bearing.

Synthesis, crystal structure investigation and magnetism of the complex metal-rich boride series Crx(Rh1-yRuy)7-xB3 (x=0.88-1; y=0-1) with Th7Fe3-type structure

NASA Astrophysics Data System (ADS)

Misse, Patrick R. N.; Mbarki, Mohammed; Fokwa, Boniface P. T.

2012-08-01

Powder samples and single crystals of the new complex boride series Crx(Rh1-yRuy)7-xB3 (x=0.88-1; y=0-1) have been synthesized by arc-melting the elements under purified argon atmosphere on a water-cooled copper crucible. The products, which have metallic luster, were structurally characterized by single-crystal and powder X-ray diffraction as well as EDX measurements. Within the whole solid solution range the hexagonal Th7Fe3 structure type (space group P63mc, no. 186, Z=2) was identified. Single-crystal structure refinement results indicate the presence of chromium at two sites (6c and 2b) of the available three metal Wyckoff sites, with a pronounced preference for the 6c site. An unexpected Rh/Ru site preference was found in the Ru-rich region only, leading to two different magnetic behaviors in the solid solution: The Rh-rich region shows a temperature-independent (Pauli) paramagnetism whereas an additional temperature-dependent paramagnetic component is found in the Ru-rich region.

On the transferability of electron density in binary vanadium borides VB, V3B4 and VB2.

PubMed

Terlan, Bürgehan; Akselrud, Lev; Baranov, Alexey I; Borrmann, Horst; Grin, Yuri

2015-12-01

Binary vanadium borides are suitable model systems for a systematic analysis of the transferability concept in intermetallic compounds due to chemical intergrowth in their crystal structures. In order to underline this structural relationship, topological properties of the electron density in VB, V3B4 and VB2 reconstructed from high-resolution single-crystal X-ray diffraction data as well as derived from quantum chemical calculations, are analysed in terms of Bader's Quantum Theory of Atoms in Molecules [Bader (1990). Atoms in Molecules: A Quantum Theory, 1st ed. Oxford: Clarendon Press]. The compounds VB, V3B4 and VB2 are characterized by a charge transfer from the metal to boron together with two predominant atomic interactions, the shared covalent B-B interactions and the polar covalent B-M interactions. The resembling features of the crystal structures are well reflected by the respective B-B interatomic distances as well as by ρ(r) values at the B-B bond critical points. The latter decrease with an increase in the corresponding interatomic distances. The B-B bonds show transferable electron density properties at bond critical points depending on the respective bond distances.

PHYSICOCHEMICAL INTERACTION OF MANGANESE WITH NIOBIUM (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Savitskii, E.M.; Kopetskii, Ch.V.

1960-03-01

Microstructural, x-ray phase, and thermal analyses as well as hardness and microhardness determinations were performed on different manganese alloys containing 2.26, with a small Nb content have a two-phase structure characteristic of a eutectic. With increasing Nb content, an increasing amount of an intermetallic compound is formed. With a 2.98 wt.% Nb alloy interference lines of only alpha -Mn with a lattice parameter a = 8.892 kX in the annealed state or of ore resistant t -Mn with a lattice parameter a = 6.290 kX in the molten state can be detected by x-ray analysis. With 5.64 wt.% Nb, linesmore » of a new phase can be detected whose intensities increase with increasing Nb content. This new phase is an intermetallic compound Mn/sub 2/Nb Laves phase with a structure of the MgZn/sub 2/ type. The lattice parameters of the Mn/sub 2/Nb phase are: a = 4.881 kX, c = 7.953 kX, c/a = 1.629. With increasing niobium content the hardness values fall from 900 to 950 hg/mm/sup 2/ for pure manganese to 650 to 700 kg/mm/sup 2/ for the 29.85 wt.% niobium alloy. The hardness of the intermetallic compound is less than the hardness of the alpha -Mn. Thermal analysis showed that additions of niobium to manganese significantly increased the temperature of the alpha = ore resistant t transition which is shifted from 727 tained C for pure manganese to 800 tained C for the alloys. A ore resistant t transition takes place at 1135 tained C by a peritectic reaction. Fusion of a eutectic mixture of -Mn and Mn/sub 2/ Nb occurs at 1220 tained C. The intermetallic compound MnNb melts at 1500 tained C. A phase diagram for the Mn-Nb system is constructed on the basis of these resuits. (TTT) Iodide-derived titanium (99.97%) and neodymium (99.8%) were fused in an electric arc furnace in a helium atmosphere to prepare nine alloys with a necdymium content of 0 to 10%. Smelted and forged samples were annealed in evacuated quartz ampoules for 25 hours at 1000 tained C and 100 hours at 850 tained C. Samples of alloys were quenched in water from temperatures of 600, 800, 850, 890, 920, 1000, and 1100 tained C to determine the state of the system at higher temperatures. Microscopic analyses of phases showed that addition of neodymium stabilizes the alpha -phase. The microhardness of the phase is about 70 kg/mm/sup 2/. Apparently, no intermetallic compounds are formed in the Ti-Nd system. The limiting saturation of the alpha -solid solution at 600 tained C is 1.8 wt.% Nd, as determined from microhardness values on quenched samples of variable neodymium composition. The solubility of neodymium is somewhat greater than the solubility of lanthanum and cerium in alpha -titunium because of the lanthanide contraction. Brinnell hardness values, yield strength, elongation, and reduction in cross- section area were also determined at room temperature. Neodymium is more effective than lanthanum or cerium in increasing the handness and strength of titanium. Small additions of Nd(0.5%) decrease the plasticity slightly. The addition of 1.2 wt.% Ce increases the yield strength of titanium from 32 to 38 to 40 hg/mm/sup 2/, while the same amount of neodymium increases the yield strength to 48 to 50 kg/mm/sup 2/. The strength of Ti-Nd alloys continues to increase even with the appearance of a second phase in the alloy, while in the TiLa and Ti- Ce systems a decrease in strength and a sharp drop in plasticity occurs upon the appearance of a second phase. The solubility of neodymium in alpha -titanium varies considerably with temperature. Hence, a noticeable aging effect can be expected, but this must be confirmed by experiment. (TTT)« less

Optimization of diode-pumped doubly QML laser with neodymium-doped vanadate crystals at 1.34 μm

NASA Astrophysics Data System (ADS)

Zhang, Gang; Jiao, Zhiyong

2018-05-01

We present a theoretical model for a diode-pumped, 1.34 μm V3+:YAG laser that is equipped with an acoustic-optic modulator. The model includes the loss introduced by the acoustic-optic modulator combined with the physical properties of the laser resonator, the neodymium-doped vanadate crystals and the output coupler. The parameters are adjusted within a reasonable range to optimize the pulse output characteristics. A typical Q-switched and mode-locked Nd:Lu0.15Y0.85VO4 laser at 1.34 μm with acoustic-optic modulator and V3+:YAG is set up, and the experimental output characteristics are consistent with the theoretical simulation results.

Neodymium oxide: A new thermoluminescent material for gamma dosimetry

NASA Astrophysics Data System (ADS)

Soliman, C.

2006-10-01

In the present study thermoluminescence (TL) glow curves of commercial and gamma (0.001 Gy to 100 kGy) exposed neodymium oxide (Nd 2O 3) have been investigated. The commercial glow curve is simple with TL peaks at 310, 350 and 385 °C. The TL sensitivity was enhanced to ˜4.7 times the original value when the investigated material was subject to pre-heating treatment at 800 °C for 1 h. The effect of storage time at room temperature has been monitored for different γ-doses. The combination of good γ-dose response and high stability of defects offer the possibility of applying the investigated material to γ-ray dosimetry in radiotherapy and experimental radiology range.

Solution-processed high-mobility neodymium-substituted indium oxide thin-film transistors formed by facile patterning based on aqueous precursors

NASA Astrophysics Data System (ADS)

Lin, Zhenguo; Lan, Linfeng; Sun, Sheng; Li, Yuzhi; Song, Wei; Gao, Peixiong; Song, Erlong; Zhang, Peng; Li, Meiling; Wang, Lei; Peng, Junbiao

2017-03-01

Solution-processed neodymium-substituted indium oxide (InNdO) thin-film transistors (TFTs) based on gel-like aqueous precursors were fabricated with a surface-selective deposition technique associated with ultraviolet irradiation. The Nd concentration can be easily tuned by changing the ratio of Nd2O3 to In2O3 precursors. It was found that Nd played roles of suppressing grain growth, suppressing oxygen vacancy formation, and increasing the electrical stability of TFTs. The InNdO TFT with a Nd:In ratio of 0.02:1 exhibited a mobility of as high as 15.6 cm2 V-1 s-1 with improved stability under gate-bias stress.

Luminescence and scintillation properties of XPO4:Nd3+ (X = Y, Lu, Sc, La) crystals

NASA Astrophysics Data System (ADS)

Makowski, Michał; Witkowski, Marcin E.; Drozdowski, Winicjusz; Wojtowicz, Andrzej J.; Wisniewski, Krzysztof; Boatner, Lynn A.

2018-05-01

Due to their very fast short-wavelength emission, neodymium-doped materials are a subject of current interest as potential scintillators. Although the initial reports regarding neodymium-doped orthophosphates (in crystalline form) and their scintillation properties appeared almost twenty years ago, they remain an interesting class of materials since there is no in-depth understanding of their fundamental scintillation mechanism. In the present research, we focus on the crystalline systems: XPO4:Nd3+, where X = Y, Lu, La, Sc. The pulse height, optical absorption, radioluminescence and photoluminescence spectra were investigated and are reported here for various temperatures from 10 to 350 K. Additionally, results of both low and high temperature thermoluminescence measurements are reported in this communication.

Prediction of the new efficient permanent magnet SmCoNiFe 3

DOE PAGES

Soderlind, P.; Landa, A.; Locht, I. L. M.; ...

2017-09-14

Here, we propose a new efficient permanent magnet, SmCoNiFe 3, which is a development of the well-known SmCo 5 prototype. More modern neodymium magnets of the Nd-Fe-B type have an advantage over SmCo 5 because of their greater maximum energy products due to their iron-rich stoichiometry. Our new magnet, however, removes most of this disadvantage of SmCo 5 while preserving its superior high-temperature efficiency over the neodymium magnets. We show by means of first-principles electronic-structure calculations that SmCoNiFe 3 has very favorable magnetic properties and could therefore potentially replace SmCo 5 or Nd-Fe-B types in various applications.

SPECTRAL AND MODE PROPERTIES OF SOLID-STATE LASERS AND OPTICAL DYNAMIC EFFECTS.

DTIC Science & Technology

LASERS , OPTICAL PROPERTIES), THERMAL PROPERTIES, FREQUENCY, RUBY, KERR CELLS, ELECTROMAGNETIC PULSES, PHASE LOCKED SYSTEMS, GARNET, NEODYMIUM, CAVITY RESONATORS, INTERFEROMETERS, LIGHT PULSES, PROPAGATION

Vapor pressure and evaporation rate of certain heat-resistant compounds in a vacuum at high temperatures

NASA Technical Reports Server (NTRS)

Bolgar, A. S.; Verkhoglyadova, T. S.; Samsonov, G. V.

1985-01-01

The vapor pressure and evaporation rate of borides of titanium, zirconium, and chrome; and of strontium and carbides of titanium, zirconium, and chrome, molybdenum silicide; and nitrides of titanium, niobium, and tantalum in a vacuum were studied. It is concluded that all subject compounds evaporate by molecular structures except AlB sub 12' which dissociates, losing the aluminum.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Erdemir, Ali; Eryilmaz, Osman Levent; Urgen, Mustafa

A nanocomposite coating and method of making and using the coating. The nanocomposite coating is disposed on a base material, such as a metal or ceramic; and the nanocomposite consists essentially of a matrix of an alloy selected from the group of Cu, Ni, Pd, Pt and Re which are catalytically active for cracking of carbon bonds in oils and greases and a grain structure selected from the group of borides, carbides and nitrides.

LINER FOR EXTRUSION BILLET CONTAINERS

DTIC Science & Technology

Shrink-fit assembly device for buildup of ceramic-coated liner and sleeve assemblies was tested and modified to develop desired temperatures and...preliminary evaluation of suitability for extrusion liner use. Procedures were developed for welding short, hollow ceramic cylinders of high-strength metal...carbides and borides to form a ceramic extrusion liner of suitable length. Disassembly tooling for rapid separation of shrink-fitted sleeves from a worn

Correlation between thermodynamical stabilities of metal borohydrides and cation electronegativites: First-principles calculations and experiments

NASA Astrophysics Data System (ADS)

Nakamori, Yuko; Miwa, Kazutoshi; Ninomiya, Akihito; Li, Haiwen; Ohba, Nobuko; Towata, Shin-Ichi; Züttel, Andreas; Orimo, Shin-Ichi

2006-07-01

The thermodynamical stabilities for the series of metal borohydrides M(BH4)n ( M=Li , Na, K, Cu, Mg, Zn, Sc, Zr, and Hf; n=1-4 ) have been systematically investigated by first-principles calculations. The results indicated that an ionic bonding between Mn+ cations and [BH4]- anions exists in M(BH4)n , and the charge transfer from Mn+ cations to [BH4]- anions is a key feature for the stability of M(BH4)n . A good correlation between the heat of formation ΔHboro of M(BH4)n and the Pauling electronegativity of the cation χP can be found, which is represented by the linear relation, ΔHboro=248.7χP-390.8 in the unit of kJ/mol BH4 . In order to confirm the predicted correlation experimentally, the hydrogen desorption reactions were studied for M(BH4)n ( M=Li , Na, K, Mg, Zn, Sc, Zr, and Hf), where the samples of the later five borohydrides were mechanochemically synthesized. The thermal desorption analyses indicate that LiBH4 , NaBH4 , and KBH4 desorb hydrogen to hydride phases. Mg(BH4)2 , Sc(BH4)3 , and Zr(BH4)4 show multistep desorption reactions through the intermediate phases of hydrides and/or borides. On the other hand, Zn(BH4)2 desorbs hydrogen and borane to elemental Zn due to instabilities of Zn hydride and boride. A correlation between the desorption temperature Td and the Pauling electronegativity χP is observed experimentally and so χP is an indicator to approximately estimate the stability of M(BH4)n . The enthalpy change for the desorption reaction, ΔHdes , is estimated using the predicted ΔHboro and the reported data for decomposed product, ΔHhyd/boride . The estimated ΔHdes show a good correlation with the observed Td , indicating that the predicted stability of borohydride is experimentally supported. These results are useful for exploring M(BH4)n with appropriate stability as hydrogen storage materials.

Complete titanium substitution by boron in a tetragonal prism: exploring the complex boride series Ti(3-x)Ru(5-y)Ir(y)B(2+x) (0 ≤ x ≤ 1 and 1 < y < 3) by experiment and theory.

PubMed

Fokwa, Boniface P T; Hermus, Martin

2011-04-18

Polycrystalline samples and single crystals of four members of the new complex boride series Ti(3-x)Ru(5-y)Ir(y)B(2+x) (0 ≤ x ≤ 1 and 1 < y < 3) were synthesized by arc-melting the elements in a water-cooled copper crucible under an argon atmosphere. The new silvery phases were structurally characterized by powder and single-crystal X-ray diffraction as well as energy- and wavelength-dispersive X-ray spectroscopy analyses. They crystallize with the tetragonal Ti(3)Co(5)B(2) structure type in space group P4/mbm (No. 127). Tetragonal prisms of Ru/Ir atoms are filled with titanium in the boron-poorest phase (Ti(3)Ru(2.9)Ir(2.1)B(2)). Gradual substitution of titanium by boron then results in the successive filling of this site by a Ti/B mixture en route to the complete boron occupation, leading to the boron-richest phase (Ti(2)Ru(2.8)Ir(2.2)B(3)). Furthermore, both ruthenium and iridium share two sites in these structures, but a clear Ru/Ir site preference is found. First-principles density functional theory calculations (Vienna ab initio simulation package) on appropriate structural models (using a supercell approach) have provided more evidence on the stability of the boron-richest and -poorest phases, and the calculated lattice parameters corroborate very well with the experimentally found ones. Linear muffin-tin orbital atomic sphere approximation calculations further supported these findings through crystal orbital Hamilton population bonding analyses, which also show that the Ru/Ir-B and Ru/Ir-Ti heteroatomic interactions are mainly responsible for the structural stability of these compounds. Furthermore, some stable and unstable phases of this complex series could be predicted using the rigid-band model. According to the density of states analyses, all phases should be metallic conductors, as was expected from these metal-rich borides.

Absorption spectra of 4f electron transitions of neodymium and erbium with 8-hydroxyquinoline-5-sulphonic acid and diethylamine systems and its analytical application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang Naixing; Qi Ping

1992-06-01

In this paper the absorption spectra of 4f electron transitions of the systems of neodymium and erbium with 8-hydroxyquinoline-5-sulphonic acid and diethylamine have been studied by normal and third-derivative spectrophotometry. Their molar absorptivities are 80 1.mol{sup {minus}1}.cm{sup {minus}1} for neodymium and 65 1.mol{sup {minus}1}.cm{sup {minus}1} for erbium. Use of the third-derivative spectra, eliminates the interference by other rare earths and increases the sensitivity for Nd and Er. The derivative molar absorptivities are 390 1.mol{sup {minus}1}.cm{sup {minus}1} for Nd and 367 1.mol{sup {minus}1}.cm{sup {minus}1} for Er. The calibration graphs were linear up to 11.8 {mu}g/ml of Nd and 12.3 {mu}g/ml ofmore » Er, respectively. The relative standard deviations evaluated from eleven independent determinations of 7.2 {mu}g/ml (for Nd) and 8.3 {mu}g/ml (for Er) are 1.3% and 1.4%, respectively. The detection limits are 0.2 {mu}g/ml for Nd and 0.3 {mu}g/ml for Er. The method has been developed for determining those two elements in mixture of lanthanides by means of the third-derivative spectra and the analytical results obtained are satisfactory.« less

The characterisation and application of a pulsed neodymium YAG laser DGV system to a time-varying high-speed flow

NASA Astrophysics Data System (ADS)

Thorpe, S. J.; Quinlan, N.; Ainsworth, R. W.

2000-10-01

Doppler Global Velocimetry (DGV) is a whole-field measurement technique which has attracted significant interest from the fluid-flow research community since its introduction in 1991. Practical implementations of the methodology have focused on two principal laser light sources: the argon ion laser, applied to steady state or slowly varying flows; and the pulsed neodymium YAG laser for the measurement of instantaneous velocity fields. However, the emphasis in the published literature has been very much on research using the argon laser. This paper reports the application of a Q-switched, injection-seeded neodymium YAG laser to the proven Oxford DGV system, and the use of this combination in a short duration unsteady high-speed flow. The pertinent characteristics of the apparatus are described, and the impact of these on the integrity of the resulting velocity measurements is presented. Adaptations to the commercial laser system that make it suitable for application to the measurement of transient high-speed flows are described. Finally, the application of this system to a short duration unsteady flow is described. This application is based on the flow found in a new type of transdermal drug delivery device, where particles of the drug material are projected at high speed through the skin. Whole-field velocities are recorded, and values as high as 800 m/ s are evident.

Development studies for a novel wet oxidation process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dhooge, P.M.; Hakim, L.B.

1994-01-01

A catalytic wet oxidation process (DETOX), which uses an acidic iron solution to oxidize organic compounds to carbon dioxide, water, and other simple products, was investigated as a potential method for the treatment of multicomponent hazardous and mixed wastes. The organic compounds picric acid, poly(vinyl chloride), tetrachlorothiophene, pentachloropyridine, Aroclor 1260 (a polychlorinated biphenyl), and hexachlorobenzene were oxidized in 125 ml reaction vessels. The metals arsenic, barium, beryllium, cadmium, cerium (as a surrogate for plutonium), chromium, lead, mercury, neodymium (as a surrogate for uranium), nickel, and vanadium were tested in the DETOX solution. Barium, beryllium, cerium, chromium, mercury, neodymium, nickel, andmore » vanadium were all found to be very soluble (>100 g/l) in the DETOX chloride-based solution. Arsenic, barium, cadmium, and lead solubilities were lower. Lead could be selectively precipitated from the DETOX solution. Chromium(VI) was reduced to relatively non-toxic chromium(III) by the solution. Six soils were contaminated with arsenic, barium, beryllium, chromium, lead, and neodymium oxides at approximately 0.1% by weight, and benzene, trichloroethene, mineral oil, and Aroclor 1260 at approximately 5% by weight total, and 5.g amounts treated with the DETOX solution in unstirred 125. ml reaction bombs. It is felt that soil treatment in a properly designed system is entirely possible despite incomplete oxidation of the less volatile organic materials in these unstirred tests.« less

Neodymium doped hydroxyapatite theranostic nanoplatforms for colon specific drug delivery applications.

PubMed

Victor, Sunita Prem; Paul, Willi; Vineeth, V M; Komeri, Remya; Jayabalan, Muthu; Sharma, Chandra P

2016-09-01

Theranostic nanoplatforms integrate therapeutic payloads with diagnostic agents, and help monitor therapeutic response. In this regard, stimuli responsive nanoplatforms further favour combinatorial therapeutic approach that can considerably improve efficacy and specificity of treatment. Herein, we present the engineering of a smart theranostic nanoplatform based on neodymium doped hydroxyapatite (HAN). The presence of neodymium endows the HAN nanoplatforms with near-infrared fluorescence capability. These HAN nanoparticles were then subsequently modified with alginic acid (HANA) to confer pH responsiveness to the synthesized nanoplatforms delivering them to the colon after oral administration. These nanoplatforms possessing optimum size, needle shaped morphology and negative zeta potential, are conducive to cellular internalization. On excitation at 410nm they exhibit near infrared emission at 670nm unraveling their theranostic capabilities. Cytotoxic effects systematically assessed using MTT and live dead assays reveal excellent viability. Raman microscopic imaging technique used to visualize uptake in HeLa cells demonstrate increased uptake from 4 to 16h, with growing cluster size and localization in the cytoplasm. Moreover the concomitant presence of alginic acid manifested advantages of augmented loading and pH dependent release profiles of the model drug, 4 acetyl salicylic acid (4ASA). We could thus establish a theranostic system for early tumour detection, targeted tumour therapy and monitoring of colon cancer that can be administered via the oral route. Copyright © 2016 Elsevier B.V. All rights reserved.

Q-switched Nd: YAG laser versus trichloroacetic acid peeling in the treatment of melasma among Egyptian patients.

PubMed

Moubasher, Alaa E A; Youssef, Eman M K; Abou-Taleb, Doaa A E

2014-08-01

Melasma is a common disorder of facial hyperpigmentation that is often resistant to treatment. To evaluate the efficacy of trichloroacetic acid (TCA) peeling in comparison with double frequency Q-switched neodymium-doped:yttrium aluminum garnet (QS-Nd:YAG) laser in the treatment of melasma. Sixty-five adult Egyptian female patients with melasma were enrolled in this study. Wood light was used for determination of the histological type of melasma. The patients were divided into 4 groups according to treatment modalities: peeling with different concentrations of TCA and double frequency QS-Nd:YAG laser. Trichloroacetic acid peeling was performed every 2 weeks up to 8 sessions, whereas laser treatment was performed every month up to 6 sessions. Melasma area and severity index (MASI) score was used before and after treatment for evaluation. Improvement percentage of MASI score was significantly higher among patients treated with TCA 25% (p < .001). Epidermal type of melasma was significantly improved compared with the dermal type (p = .0029). Q-switched neodymium-doped:yttrium aluminum garnet laser showed the highest incidence of postinflammatory hyperpigmentation (53.3%). Trichloroacetic acid peeling is effective in the treatment of melasma, TCA 25% was the most effective concentration. Q-switched neodymium-doped:yttrium aluminum garnet laser is not recommended in the treatment of melasma because it was associated with the highest incidence of complications.

Luminescence and scintillation properties of XPO 4:Nd 3+ (X = Y, Lu, Sc, La) crystals

DOE PAGES

Makowski, Michal; Witkowski, Marcin E.; Drozdowski, Winicjusz; ...

2018-04-12

Due to their very fast short-wavelength emission, neodymium-doped materials are a subject of current interest as potential scintillators. Although the initial reports regarding neodymium-doped orthophosphates (in crystalline form) and their scintillation properties appeared almost twenty years ago, they remain an interesting class of materials since there is no in-depth understanding of their fundamental scintillation mechanism. In the present research, we focus on the crystalline systems: XPO 4:Nd 3+, where X = Y, Lu, La, Sc. The pulse height, optical absorption, radioluminescence and photoluminescence spectra were investigated and are reported here for various temperatures from 10 to 350 K. Here, resultsmore » of both low and high temperature thermoluminescence measurements are reported in this communication.« less

Effect of Partial Substitution of Neodymium with Praseodymium on the Magnetic and Process Properties of Sintered Magnets of Type NdFeB

NASA Astrophysics Data System (ADS)

Dormidontov, N. A.; Dormidontov, A. G.; Lileev, A. S.; Kamynin, A. V.; Lukin, A. A.

2017-01-01

The effect of substitution of neodymium with praseodymium in sintered magnets of type NdFeB on their magnetic and process properties in the concentration range of [Pr] = 0 - 13 wt.% is studied. The special features of milling of the alloys, sintering processes and heat treatments in the production of magnets containing praseodymium are discussed. Hysteresis characteristics of B r ≥ 1.2 T, H cJ ≥ 1200 kA/m, H cb ≥ 880 kA/m, H k ≥ 960 kA/m, and BH max ≥ 280 kJ/m3 are obtained for magnets with composition (in wt.%) 33 Nd, 10 Pr, 1.5 (Ti + Al + Cu), 1.3 B, the remainder Fe.

Luminescence and scintillation properties of XPO 4:Nd 3+ (X = Y, Lu, Sc, La) crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Makowski, Michal; Witkowski, Marcin E.; Drozdowski, Winicjusz

Due to their very fast short-wavelength emission, neodymium-doped materials are a subject of current interest as potential scintillators. Although the initial reports regarding neodymium-doped orthophosphates (in crystalline form) and their scintillation properties appeared almost twenty years ago, they remain an interesting class of materials since there is no in-depth understanding of their fundamental scintillation mechanism. In the present research, we focus on the crystalline systems: XPO 4:Nd 3+, where X = Y, Lu, La, Sc. The pulse height, optical absorption, radioluminescence and photoluminescence spectra were investigated and are reported here for various temperatures from 10 to 350 K. Here, resultsmore » of both low and high temperature thermoluminescence measurements are reported in this communication.« less

Coated conductors

DOEpatents

Arendt, Paul N.; Foltyn, Stephen R.; Stan, Liliana; Usov, Igor O.; Wang, Haiyan

2010-06-15

Articles are provided including a base substrate having a layer of an IBAD oriented material thereon, and, a layer of barium-containing material selected from the group consisting of barium zirconate, barium hafnate, barium titanate, barium strontium titanate, barium dysprosium zirconate, barium neodymium zirconate and barium samarium zirconate, or a cubic metal oxide material selected from the group consisting of rare earth zirconates and rare earth hafnates upon the layer of an IBAD oriented material. Such articles can further include thin films of high temperature superconductive oxides such as YBCO upon the layer of barium-containing material selected from the group consisting of barium zirconate, barium hafnate, barium titanate, barium strontium titanate, barium dysprosium zirconate, barium neodymium zirconate and barium samarium zirconate, or a cubic metal oxide material selected from the group consisting of rare earth zirconates and rare earth hafnates.

Listening to Chemical Materials: Determination of the Photophysical Parameters by Photoacoustic Spectroscopy

NASA Astrophysics Data System (ADS)

Yang, Y. T.; Zhang, S. Y.; Liu, X. J.

2012-11-01

Recently, photoacoustic (PA) spectroscopy has emerged as a valuable tool for the study of various kinds of materials. Herein, we present the results of PA spectral studies of chemical materials. First, the PA study on luminescent materials in condensed states is reported. Combining with the luminescence technique, the energy transfer efficiency and the intrinsic luminescence quantum yield are determined for a europium (III) complex in the glassy state, smectic A phase, and the isotropic liquid. Second, neodymium (III) compounds with l-glycine, l-phenylalanine, and l-tryptophan are synthesized and their PA spectra are reported. The nephelauxetic ratio and Sinha parameter are calculated based on the PA spectra. The environmental effect on the f-f transitions of the neodymium(III) ion is also studied.

Long-pulsed neodymium:yttrium-aluminum-garnet laser treatment for hypertrophic port-wine stains on the lips.

PubMed

Kono, Taro; Frederick Groff, William; Chan, Henry H; Sakurai, Hiroyuki; Yamaki, Takashi

2009-03-01

Pulsed dye laser (PDL) treatment of hypertrophic port-wine stains (PWSs) on the lips has demonstrated poor efficacy and a potential risk of dyspigmentation. PDL-resistant hypertrophic PWS may require treatment with deeper penetrating lasers such as a 1064-nm neodymium:yttrium-aluminum-garnet (Nd:YAG) laser. The objective of this clinical study was to evaluate the efficacy and safety of a Nd:YAG laser for the treatment of hypertrophic PWSs on the lips. Ten patients (four were male and six were female) with hypertrophic PWSs on the lips were recruited in this study. Eight patients showed good to excellent improvement without complications. In conclusion, the Nd:YAG laser is safe and effective for treating hypertrophic PWSs on the lips.

Intracavity frequency doubling of a continuous-wave, diode-laser-pumped neodymium lanthanum scandium borate laser.

PubMed

Meyn, J P; Huber, G

1994-09-15

Neodymium-doped lanthanum scandium borate [Nd:LaSc(3)(BO(3))(4)] is a new material for efficient and compact diode-pumped solid-state lasers. A simple plane-plane 3-mm-long resonator is formed by a coated Nd(10%):LaSc(3)(BO(3))(4) crystal and a coated potassium titanyl phosphate (KTP) crystal. The second-harmonic output power at 531 nm is 522 mW at 2.05-W incident pump power of the diode laser. The corresponding optical efficiency is 25%, and the conversion efficiency from the fundamental to the second harmonic is 55%. The wellknown chaotic power fluctuations of intracavity frequency-doubled lasers (green problem) are avoided by use of a short KTP crystal, between 0.5 and 2 mm in length.

Ternary boride product and process

NASA Technical Reports Server (NTRS)

Clougherty, Edward V. (Inventor)

1976-01-01

A hard, tough, strong ceramic body is formed by hot pressing a mixture of a powdered metal and a powdered metal diboride. The metal employed is zirconium, titanium or hafnium and the diboride is the diboride of a different member of the same group of zirconium, titanium or hafnium to form a ternary composition. During hot pressing at temperatures above about 2,000.degree.F., a substantial proportion of acicular ternary monoboride is formed.

Mechanical, Electronic and Optical Properties of Two Phases of NbB4: First-Principles Calculations

NASA Astrophysics Data System (ADS)

Yang, Ruike; Ma, Shaowei; Wei, Qun; Zhang, Dongyun

2018-05-01

As transition metal borides have been successfully synthesised, the study of the combination of transition metal and boron is another effective way to investigate the properties of boride. We have predicted the novel phase Amm2-NbB4. Using the Cambridge Serial Total Energy Package (CASTEP) code, we further researched on the mechanical, electronic and optical properties of C2/c- and Amm2-NbB4. It is found that both the phases of NbB4 are dynamically and mechanically stable at 0 and 100 GPa. Their Vickers hardness values are both 34 GPa, which indicate that they are hard materials. The band gap of C2/c-NbB4 is 0.145 eV, which indicates that it is a semiconductor (or metalloid) at 0 GPa. For the Amm2-NbB4, the band structure without band gap indicates it is a metal at 0 GPa. The optical properties of these two structures are similar. At 0 eV, the real part of dielectric function is 28.8 for C2/c-NbB4, and the real part value for Amm2-NbB4 is 43. We hope our work will provide some help to the experimental work about the technology of the material.

A study of the microstructure of a rapidly solidified nickel-base superalloy modified with boron. M.S. Thesis. Final Contractor Report

NASA Technical Reports Server (NTRS)

Speck, J. S.

1986-01-01

The microstructures of melt-spun superalloy ribbons with variable boron levels have been studied by transmission electron microscopy. The base alloy was of approximate composition Ni-11% Cr-5%Mo-5%Al-4%Ti with boron levels of 0.06, 0.12, and 0.60 percent (all by weight). Thirty micron thick ribbons display an equiaxed chill zone near the wheel contact side which develops into primary dendrite arms in the ribbon center. Secondary dendrite arms are observed near the ribbon free surface. In the higher boron bearing alloys, boride precipitates are observed along grain boundaries. A concerted effort has been made to elucidate true grain shapes by the use of bright field/dark field microscopy. In the low boron alloy, grain shapes are often convex, and grain faces are flat. Boundary faces frequently have large curvature, and grain shapes form concave polygons in the higher boron level alloys. It is proposed that just after solidification, in all of the alloys studied, grain shapes were initially concave and boundaries were wavy. Boundary straightening is presumed to occur on cooling in the low boron alloy. Boundary migration is precluded in the higher boron alloys by fast precipitation of borides at internal interfaces.

Demonstrating Paramagnetism Using Liquid Nitrogen.

ERIC Educational Resources Information Center

Simmonds, Ray; And Others

1994-01-01

Describes how liquid nitrogen is attracted to the poles of neodymium magnets. Nitrogen is not paramagnetic, so the attraction suggests that the liquid nitrogen contains a small amount of oxygen, which causes the paramagnetism. (MVL)

Potassium titanyl arsenate based cascaded optical parametric oscillator emit at 2.5 µm derived by neodymium-doped yttrium lithium fluoride laser

NASA Astrophysics Data System (ADS)

Duan, Yanmin; Zhang, Jing; Guo, Junhong; Zhu, Haiyong; Zhang, Yongchang; Xu, Changwen; Wang, Hongyan; Zhang, Yaoju

2018-04-01

We reported a potassium titanyl arsenate (KTA) based cascaded optical parametric oscillator (OPO). The secondary OPO signal light at 2.5 µm was obtained with two OPO processes in one non-critical phase matching cut KTA crystal. This cascaded OPO was driven by a Q-switched neodymium-doped yttrium lithium fluoride (Nd:YLF) laser at 1047 nm. Making full use of the negative thermal lens effect and long upper level fluorescence lifetime of Nd:YLF, signal power of 605 mW at 2503 nm was achieved with a pulse repetition frequency of 15 kHz and an incident diode pump power of 9.7 W. Therefore, the cascaded OPO derived by Q-switched Nd:YLF laser could provide high peak power pulsed laser emission in mid-infrared band.

Neodymium:YAG laser cutting of intraocular lens haptics in vitro and in vivo.

PubMed

Feder, J M; Rosenberg, M A; Farber, M D

1989-09-01

Various complications following intraocular lens (IOL) surgery result in explantation of the lenses. Haptic fibrosis may necessitate cutting the IOL haptics prior to removal. In this study we used the neodymium: YAG (Nd:YAG) laser to cut polypropylene and poly(methyl methacrylate) (PMMA) haptics in vitro and in rabbit eyes. In vitro we were able to cut 100% of both haptic types successfully (28 PMMA and 30 polypropylene haptics). In rabbit eyes we were able to cut 50% of the PMMA haptics and 43% of the polypropylene haptics. Poly(methyl methacrylate) haptics were easier to cut in vitro and in vivo than polypropylene haptics, requiring fewer shots for transection. Complications of Nd:YAG laser use frequently interfered with haptic transections in rabbit eyes. Haptic transection may be more easily accomplished in human eyes.

Commentary: Is There Clinical Benefit From Using a Diode or Neodymium:Yttrium-Aluminum-Garnet Laser in the Treatment of Periodontitis?

PubMed

Cobb, Charles M

2016-10-01

Despite a quarter of a century of laser research, there is a persistent debate regarding the efficacy of dental lasers in the treatment of periodontitis or periodontal maintenance therapy. There are many claims and much hyperbole surrounding the use of lasers, either as a monotherapy or adjunctive to scaling and root planing, to treat periodontitis. There is little evidence that using a diode or neodymium:yttrium-aluminum-garnet laser adds clinical value over and above conventional non-surgical or surgical periodontal treatment. There is a significant need for better designed human clinical trials. Data from such trials should be analyzed according to initial probing depth and characteristics of the treated sites, such as non-molar, molar flat surfaces, and molar furcations, and evaluated for long-term post-treatment results.

Models for the Immediate Environment of Ions in Aqueous Solutions of Neodymium Chloride

NASA Astrophysics Data System (ADS)

Smirnov, P. R.; Grechin, O. V.

2018-01-01

Radial distribution functions of neodymium chloride aqueous solutions in a wide range of concentrations under ambient conditions are calculated from experimental data obtained earlier via X-ray diffraction analysis. Different models of the structural organization of the system are developed. The optimum versions are determined by calculating theoretical functions for each model and comparing their fit to the experimental functions. Such quantitative characteristics of the immediate environment of Nd3+ and Cl- ions as coordination numbers, interparticle distances, and varieties of ion pairs are determined. It is shown that the average number of water molecules in the first coordination sphere of the cation falls from 9 to 6.2 as the concentration rises. The structure of the systems over the whole range of concentrations is determined by ion associates of the noncontact type.

[Effect of phosphate on the exchangeable form and the bioavailability of exogenous neodymium in soil].

PubMed

Xu, Z; Li, D; Yang, J; Peng, A

2001-05-01

Effects of phosphate on the exchangeable form and the bioavailability of exogenous neodymium (Nd) in soil were studied with 147Nd isotopic tracer. Exchangeable Nd was extracted with solution (pH8.2) of NaAc. The results indicated that Nd beyond 99.5% was adsorbed by soil whether phosphate exists in soil or not. Phosphate can precipitate dramatically Nd3+. And the Nd phosphate precipitates may set limits on the concentration of exchangeable Nd observed in soil. KH2PO4 ranging from 0.3 g.kg-1 to 1.5 g.kg-1 make a uniform impact on the exchangeable form of Nd. In addition, phosphate in soil can inhibit wheat seedling to absorb Nd. The concentration of exchangeable Nd is correlated significantly with the content of Nd in wheat seedling.

Immunologically induced peliosis hepatis in rats.

PubMed Central

Husztik, E.; Lázár, G.; Szabó, E.

1984-01-01

Peliosis hepatis has been induced immunologically with anti-rat glomerular basal membrane rabbit serum in rats pre-sensitized with a rare earth metal complex, neodymium pyrocatechin disulphonate (NPD). This is the first experimental evidence that peliosis hepatis may develop as a result of an immunological process. It is noteworthy that in this experimental form of peliosis hepatis and in that observed earlier in rats treated with basic polyglutamic acid derivatives, severe defibrination was detected and, as in most human cases, not only the liver but other organs were also involved in the peliotic lesions. Since the rare earth metal compounds, among them the pyrocatechin disulphonate complex of neodymium, depress the reticulo-endothelial activity, a role of the reticulo-endothelial system in the pathogenesis of this experimental form of peliosis hepatis is suggested. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:6547617

Neodymium:yttrium-aluminum-garnet laser fusion of endarterectomy flaps.

PubMed

Humphrey, P W; Slocum, M M; Loy, T S; Silver, D

1995-07-01

This study evaluated the efficacy of neodymium:yttrium-aluminum-garnet laser welding of flaps in canine arteries and in securing the distal flap during human carotid endarterectomy. Endarterectomy flaps were created in both common carotid and both common femoral arteries in 12 dogs. The flaps were repaired with either the neodymium:yttrium-aluminum-garnet laser or with 6-0 polypropylene sutures. The arteries were removed after duplex scanning at either 7 or 28 days. Eighteen high carotid endarterectomy flaps in 16 patients have been subsequently secured with the laser welding technique. Laser repairs (125 +/- 19 joule) of the canine arteries were completed more quickly than suture repairs (mean 25 seconds vs 135 seconds, respectively; p < 0.04). Duplex ultrasonography revealed no discernable differences between the two groups of arteries. Arteries studied at 7 days revealed three microscopic flaps (two suture, one laser), more subintimal fibroblastic proliferation in suture than laser-repaired carotid arteries (3: 1, p = 0.0530), and similar amounts of inflammation in suture- and laser-repaired arteries. Arteries studied at 28 days revealed one microscopic intimal flap (suture-repaired); equal fibroblastic and inflammatory responses in suture- and laser-repaired vessels; and no evidence of laser thermal injury. Eighteen carotid endarterectomy flaps have been successfully fused with no immediate or long-term complications in 16 patients (follow-up of 0 to 24 months). Laser fusion appears to be a safe and effective method for securing distal carotid endarterectomy flaps.

Effect of mixing Ce{sup 3+} and Nd{sup 3+} ions in equimolar ratio on structural, optical and dielectric properties on pure cerium orthovanadate and neodymium orthovanadate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verma, Seema; Gupta, Rashmi; Bamzai, K.K., E-mail: kkbamz@yahoo.com

2016-09-15

Highlights: • CeV, NdV and mixed CeNdV nanoparticle prepared by chemical co precipitation method. • With mixing of Ce{sup 3+} and Nd{sup 3+} morphology is totally changed in mixed CeNdV. • Optical band energy of CeV, NdV and CeNdV shows good photocatalyst under UV light. • Conduction mechanism in CeV due to large polaron and small polaron in CeNdV. - Abstract: Cerium orthovanadate, neodymium orthovanadate and mixed cerium neodymium orthovanadate nanoparticles was prepared by co-precipitation method. Powder X-ray diffraction reveals tetragonal zircon structure. Slight increase in lattice parameter, volume and decrease in X-ray density inferred that Ce{sup 3+} and Nd{supmore » 3+} ion replaces each other. Transmission electron microscopy suggests change in morphology with the effect of mixing and validates formation of nanocrystalline material. The infrared transmittance spectrum confirmed the presence of various functional groups. Dielectric properties as function of frequency show dielectric constant and loss tangent decreases with increase in frequency which is due to Maxwell–Wagner type interfacial polarization. The variation of AC conductivity measurement with frequency suggests conduction mechanism due to large polaron hopping in CeV whereas small polaron in mixed CeNdV. The activation energy decreases with rising frequency indicates the conduction mechanism is based on polaron hopping between localized states in disordered manner.« less

Global flows of critical metals necessary for low-carbon technologies: the case of neodymium, cobalt, and platinum.

PubMed

Nansai, Keisuke; Nakajima, Kenichi; Kagawa, Shigemi; Kondo, Yasushi; Suh, Sangwon; Shigetomi, Yosuke; Oshita, Yuko

2014-01-01

This study, encompassing 231 countries and regions, quantifies the global transfer of three critical metals (neodymium, cobalt, and platinum) considered vital for low-carbon technologies by means of material flow analysis (MFA), using trade data (BACI) and the metal contents of trade commodities, resolving the optimization problem to ensure the material balance of the metals within each country and region. The study shows that in 2005 international trade led to global flows of 18.6 kt of neodymium, 154 kt of cobalt, and 402 t of platinum and identifies the main commodities and top 50 bilateral trade links embodying these metals. To explore the issue of consumption efficiency, the flows were characterized according to the technological level of each country or region and divided into three types: green ("efficient use"), yellow ("moderately efficient use"), and red ("inefficient use"). On this basis, the shares of green, yellow, and red flows in the aggregate global flow of Nd were found to be 1.2%, 98%, and 1.2%, respectively. For Co, the respective figures are 53%, 28%, and 19%, and for Pt 15%, 84%, and 0.87%. Furthermore, a simple indicator focusing on the composition of the three colored flows for each commodity was developed to identify trade commodities that should be prioritized for urgent technical improvement to reduce wasteful use of the metals. Based on the indicator, we discuss logical, strategic identification of the responsibilities and roles of the countries involved in the global flows.

Method to produce catalytically active nanocomposite coatings

DOEpatents

Erdemir, Ali; Eryilmaz, Osman Levent; Urgen, Mustafa; Kazmanli, Kursat

2016-02-09

A nanocomposite coating and method of making and using the coating. The nanocomposite coating is disposed on a base material, such as a metal or ceramic; and the nanocomposite consists essentially of a matrix of an alloy selected from the group of Cu, Ni, Pd, Pt and Re which are catalytically active for cracking of carbon bonds in oils and greases and a grain structure selected from the group of borides, carbides and nitrides.

High-Temperature Ceramic Matrix Composite with High Corrosion Resistance

DTIC Science & Technology

2010-06-02

ceramics with silicide additives may be explained in the following ways: 1) metal oxide, for example Ta2O5, formed at oxidation of TaSi2, in the...practically monophase ones, possibly, the additives of corresponding metals in silicide powders were present in insignificant amounts. For...boride with zirconium silicide we prepared the mixtures with 20 vol. % of silicide , the latter being hot pressed in the temperature range of 1600

Computer Modeling of Ceramic Boride Composites

DTIC Science & Technology

2014-11-01

the reinforcer deform elastically, for the theoretical strength of the composite it can be written [46] BBBAAABBAAK EE δεδεσδσδσ +=+= (51) where...coefficients of thermal expansion. Approximately linear expansion coefficient of the composite is determined by the relation [52] EEE BBBAAAk...1 δαδαα ⋅+⋅= , (58) where AE and BE are Young moduli of components, and E – average modulus for composition BBAA EEE δδ

Ground State Structures of Boron-Rich Rhodium Boride: An Ab Initio Study

NASA Astrophysics Data System (ADS)

Chu, Bin-Hua; Zhao, Yuan; Yan, Jin-Liang; Li, Da

2018-01-01

Not Available Supported by the Natural Science Foundation of Shandong Province under Grant Nos ZR2016AP02, ZR2016FM38 and ZR2016EMP01, the Innovation Project of Ludong University under Grant No LB2016013, the Open Project of State Key Laboratory of Superhard Materials of Jilin University under Grant No 201605, and the National Natural Science Foundation of China under Grant Nos 11704170 and 61705097.

Investigation of the thermophysical properties of high-melting materials with the aid of a complex of instruments

NASA Technical Reports Server (NTRS)

Bolgar, A. S.; Gordiyenko, S. P.; Guseva, Y. A.; Turchanin, A. G.; Fenochka, B. V.; Fesenko, V. V.

1984-01-01

The evaporation rate, vapor pressure, heats of evaporation reaction (sublimation, dissociation), enthalpy, electrical resistance, heat capacity, emissivity, and heat conductivity of various carbides, borides, sulfides, nitrides, selenides, and phosphides were investigated. A set of high temperature high vacuum devices, calorimeters (designed for operation at 400 to 1300 K and from 1200 K), and mass spectrometers, most of which were specially developed for these studies, is described.

How to Simply Demonstrate Diamagnetic Levitation with Pencil Lead

ERIC Educational Resources Information Center

Koudelkova, Vera

2016-01-01

A new simple arrangement how to demonstrate diamagnetic levitation is presented. It uses pencil lead levitating in a track built from neodymium magnets. This arrangement can also be used as a classroom experiment.

Value analysis of neodymium content in shredder feed: toward enabling the feasibility of rare earth magnet recycling.

PubMed

Bandara, H M Dhammika; Darcy, Julia W; Apelian, Diran; Emmert, Marion H

2014-06-17

In order to facilitate the development of recycling technologies for rare earth magnets from postconsumer products, we present herein an analysis of the neodymium (Nd) content in shredder scrap. This waste stream has been chosen on the basis of current business practices for the recycling of steel, aluminum, and copper from cars and household appliances, which contain significant amounts of rare earth magnets. Using approximations based on literature data, we have calculated the average Nd content in the ferrous shredder product stream to be between 0.13 and 0.29 kg per ton of ferrous scrap. A value analysis considering rare earth metal prices between 2002 and 2013 provides values between $1.32 and $145 per ton of ferrous scrap for this material, if recoverable as pure Nd metal. Furthermore, we present an analysis of the content and value of other rare earths (Pr, Dy, Tb).

NONLINEAR OPTICAL EFFECTS AND FIBER OPTICS: Pulsed neodymium amplifier with phase conjugation and direct amplification

NASA Astrophysics Data System (ADS)

Basov, N. G.; Efimkov, V. F.; Zubarev, I. G.; Kolobrodov, V. V.; Pastukhov, S. A.; Smirnov, M. G.; Sobolev, V. B.

1988-12-01

A study was made of the characteristics of an amplifier containing neodymium-activated silicate rods, 45 mm in diameter, used in direct amplification and phase conjugation systems. At low output energies the divergence of the output radiation in the presence of a phase-conjugating mirror was half ( ~ 10- 4 rad) that in the case of direct amplification. An increase in the output power caused the divergence to rise more rapidly in the presence of a phase-conjugating mirror, which was tentatively attributed to an earlier manifestation of large-scale self-focusing. Output energies of 130 J in the case of direct amplification and 80 J in the presence of a phase-conjugating mirror were obtained when the output pulse duration was ~ 2 ns and the fraction of the total energy contained within an angle of ~ 10- 4 rad was ~ 0.3.

The contact neodymium-yttrium aluminum garnet laser. A new approach to arthroscopic laser surgery.

PubMed

O'Brien, S J; Miller, D V

1990-03-01

Arthroscopic treatment of meniscal lesions has been modified as technological advances have occurred. However, alternatives to conventional arthroscopic cutting tools, including electrocautery and CO2 lasers, have thus far met with limited success. The recent development of a sapphire tip has enabled the use of the neodymium-yttrium aluminum garnet (Nd-YAG) laser in a contact mode in a saline medium. This study compares the biology of the Nd-YAG laser to that of electrocautery and scalpel techniques with respect to its effects on articular cartilage and the meniscus. The contact Nd-YAG laser has advantages over both scalpel and electrocautery with regard to its effects on articular cartilage. It also has significant biologic advantages over electrocautery for meniscal lesions. Although in its infancy in the clinical setting, the contact Nd-YAG laser represents the possible beginning of a new era for application of laser energy in arthroscopy.

Efficient eye-safe neodymium doped composite yttrium gallium garnet crystal laser.

PubMed

Yu, Haohai; Wang, Shuxian; Han, Shuo; Wu, Kui; Su, Liangbi; Zhang, Huaijin; Wang, Zhengping; Xu, Jun; Wang, Jiyang

2014-03-15

We report a laser-diode pumped continuous-wave (cw) and passively Q-switched eye-safe laser at about 1.42 μm with the neodymium-doped yttrium gallium garnet (Nd:YGG) crystal for the first time to our knowledge. The composite Nd:YGG crystal was developed originally. A systematic comparison of laser performance between the homogeneously doped and composite Nd:YGG crystal was made, which showed that the composite Nd:YGG manifested less thermally induced effects. Cw output power of 2.06 W was obtained with the slope efficiency of 20.7%. With a V:YAG as a saturable absorber, the passive Q-switching at 1.42 μm was gotten with the pulse width, pulse energy, and peak power of 34 ns, 46.7 μJ, and 1.4 kW, respectively. The present work should provide a potential candidate for the generation of eye-safe lasers.

Feasibility study of the welding of SiC

NASA Technical Reports Server (NTRS)

Moore, T. J.

1985-01-01

In a brief study of the feasibility of welding sintered alpha-SiC, solid-state welding and brazing were investigated. Joint quality was determined solely by microstructural examination. Hot-pressure welding was shown to be feasible at 1950 C. Diffusion welding and brazing were also successful under hot isostatic pressure at 1950 C when boride, carbide, and silicide interlayers were used. Furnace brazing was accomplished at 1750 C when a TiSi2 interlayer was introduced.

Titanium Diboride Electrodeposited Coatings

DTIC Science & Technology

1977-06-01

4 Ti02. This material was deposited in the form of a porous mass or loose particles which must be leached in water and acid to remove adherent...poudres metallique par electrolyse ignee. Revue de Metallurgie, v. 45, 1948, p. 49-59. 7. POWELL, C. F. Borides in High Temperature Materials and... water solution of thallium formate-thallium malonate 50-50 mole percent mixture with a density ranging from about 5 g/cm^ at the bottom to about 2 g/cm

METHOD OF PROTECTING TANTALUM CRUCIBLES AGAINST REACTION WITH MOLTEN URANIUM

DOEpatents

Feder, H.M.; Chellew, N.R.

1960-08-16

Tantalum crucibles against reaction with molten uranium by contacting the surfaces to be protected with metallic boron (as powder, vapor, or suspension in a liquid-volatilenonreacting medium, such as acetone and petroleum oil) at about 1800 deg C in vacuum, discontinuing contact with the boron, and heating the crucibles to a temperature of between 1800 aad 2000 deg C, whereby the tantalum boride formed in the first heating step is converted to tantalum monoboride.

Alumina-based ceramic composite

DOEpatents

Alexander, Kathleen B.; Tiegs, Terry N.; Becher, Paul F.; Waters, Shirley B.

1996-01-01

An improved ceramic composite comprising oxide ceramic particulates, nonoxide ceramic particulates selected from the group consisting of carbides, borides, nitrides of silicon and transition metals and mixtures thereof, and a ductile binder selected from the group consisting of metallic, intermetallic alloys and mixtures thereof is described. The ceramic composite is made by blending powders of the ceramic particulates and the ductile to form a mixture and consolidating the mixture of under conditions of temperature and pressure sufficient to produce a densified ceramic composite.

Preliminary investigation of zirconium boride ceramals for gas-turbine blade applications

NASA Technical Reports Server (NTRS)

Hoffman, Charles A

1953-01-01

Zirconium boride ZrB2 ceramals were investigated for possible gas-turbine-blade application. Included in the study were thermal shock evaluations of disks, preliminary turbine-blade operation, and observations of oxidation resistance. Thermal shock disks of the following three compositions were studied: (a) 97.5 percent ZrB2 plus 2.5 percent B by weight; (b) 92.5 percent ZrB2 plus 7.5 percent B by weight; and (c) 100 percent ZrB2. Thermal shock disks were quenched from temperatures of 1800 degrees, 2000 degrees, 2200 degrees, and 2400 degrees F. The life of turbine blades containing 93 percent ZrB2 plus 7 percent B by weight was determined in gas-turbine tests. The blades were run at approximately 1600 degrees F and 15,000 to 26,000 rpm. The thermal shock resistance of the 97.5 percent ZrB2 plus 2.5 percent boron ceramals compares favorably with that of TiC plus Co and TiC plus Ni ceramals. Oxidation of the disks during the thermal shock evaluation was slight for the comparatively short time (8.3 hr) up through 2000 degrees F. Oxidation of a specimen was severe, however, after 100 hours at 2000 degrees F. The turbine blade performance evaluation of the 93 percent ZrB2 plus 7 percent B composition was preliminary in scope ; no conclusions can be drawn.

Probing the superconducting ground state of the rare-earth ternary boride superconductors R RuB2 (R = Lu,Y) using muon-spin rotation and relaxation

NASA Astrophysics Data System (ADS)

Barker, J. A. T.; Singh, R. P.; Hillier, A. D.; Paul, D. McK.

2018-03-01

The superconductivity in the rare-earth transition-metal ternary borides R RuB2 (where R =Lu and Y) has been investigated using muon-spin rotation and relaxation. Measurements made in zero field suggest that time-reversal symmetry is preserved upon entering the superconducting state in both materials; a small difference in depolarization is observed above and below the superconducting transition in both compounds, however, this has been attributed to quasistatic magnetic fluctuations. Transverse-field measurements of the flux-line lattice indicate that the superconductivity in both materials is fully gapped, with a conventional s -wave pairing symmetry and BCS-like magnitudes for the zero-temperature gap energies. The electronic properties of the charge carriers in the superconducting state have been calculated, with effective masses m*/me=9.8 ±0.1 and 15.0 ±0.1 in the Lu and Y compounds, respectively, with superconducting carrier densities ns=(2.73 ±0.04 ) ×1028m-3 and (2.17 ±0.02 ) ×1028m-3 . The materials have been classified according to the Uemura scheme for superconductivity, with values for Tc/TF of 1 /(414 ±6 ) and 1 /(304 ±3 ) , implying that the superconductivity may not be entirely conventional in nature.

Robustness of fossil fish teeth for seawater neodymium isotope reconstructions under variable redox conditions in an ancient shallow marine setting

NASA Astrophysics Data System (ADS)

Huck, Claire E.; van de Flierdt, Tina; Jiménez-Espejo, Francisco J.; Bohaty, Steven M.; Röhl, Ursula; Hammond, Samantha J.

2016-03-01

Fossil fish teeth from pelagic open ocean settings are considered a robust archive for preserving the neodymium (Nd) isotopic composition of ancient seawater. However, using fossil fish teeth as an archive to reconstruct seawater Nd isotopic compositions in different sedimentary redox environments and in terrigenous-dominated, shallow marine settings is less proven. To address these uncertainties, fish tooth and sediment samples from a middle Eocene section deposited proximal to the East Antarctic margin at Integrated Ocean Drilling Program Site U1356 were analyzed for major and trace element geochemistry, and Nd isotopes. Major and trace element analyses of the sediments reveal changing redox conditions throughout deposition in a shallow marine environment. However, variations in the Nd isotopic composition and rare earth element (REE) patterns of the associated fish teeth do not correspond to redox changes in the sediments. REE patterns in fish teeth at Site U1356 carry a typical mid-REE-enriched signature. However, a consistently positive Ce anomaly marks a deviation from a pure authigenic origin of REEs to the fish tooth. Neodymium isotopic compositions of cleaned and uncleaned fish teeth fall between modern seawater and local sediments and hence could be authigenic in nature, but could also be influenced by sedimentary fluxes. We conclude that the fossil fish tooth Nd isotope proxy is not sensitive to moderate changes in pore water oxygenation. However, combined studies on sediments, pore waters, fish teeth, and seawater are needed to fully understand processes driving the reconstructed signature from shallow marine sections in proximity to continental sources.

Optical properties of Nd3+ doped barium lithium fluoroborate glasses for near-infrared (NIR) emission

NASA Astrophysics Data System (ADS)

Mariselvam, K.; Arun Kumar, R.; Suresh, K.

2018-04-01

The neodymium doped barium lithium fluoroborate (Nd3+: BLFB) glasses with the chemical composition (70-x) H3BO3 - 10 Li2CO3 - 10 BaCO3- 5 CaF2-5 ZnO - x Nd2O3 (where x = 0.05, 0.1, 0.25, 0.5, 1, 2 in wt %) have been prepared by the conventional melt quenching technique and characterised through optical absorption, near infrared emission and decay-time measurements. The x-ray diffraction studies confirm the amorphous nature of the prepared glasses. The optical absorption spectra and emission spectra were recorded in the wavelength ranges of 190-1100 nm. The optical band gap (Eg) and Urbach energy (ΔE) values were calculated from the absorption spectra. The Judd-Ofelt intensity parameters were determined from the systematic analysis of the absorption spectrum of neodymium ions in the prepared glasses. The emission spectra exhibited three prominent peaks at 874, 1057, 1331 nm corresponding to the 4F3/2 → 4I9/2, 11/2, 13/2 transitions levels respectively in the near infrared region. The emission intensity of the 4F3/2 → 4I11/2 transition increases with the increase in neodymium concentration up to 0.5 wt% and the concentration quenching mechanism was observed for 1 wt% and 2 wt% concentrations. The lifetime of the 4F3/2 level was found to decrease with increasing Nd3+ ion concentration. The nature of energy transfer process was a single exponential curve which was studied for all the glasses and analysed.

DISSOLUTION AND ANALYSIS OF YELLOWCAKE COMPONENTS FOR FINGERPRINTING UOC SOURCES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hexel, Cole R; Bostick, Debra A; Kennedy, Angel K

2012-01-01

There are a number of chemical and physical parameters that might be used to help elucidate the ore body from which uranium ore concentrate (UOC) was derived. It is the variation in the concentration and isotopic composition of these components that can provide information as to the identity of the ore body from which the UOC was mined and the type of subsequent processing that has been undertaken. Oak Ridge National Laboratory (ORNL) in collaboration with Lawrence Livermore and Los Alamos National Laboratories is surveying ore characteristics of yellowcake samples from known geologic origin. The data sets are being incorporatedmore » into a national database to help in sourcing interdicted material, as well as aid in safeguards and nonproliferation activities. Geologic age and attributes from chemical processing are site-specific. Isotopic abundances of lead, neodymium, and strontium provide insight into the provenance of geologic location of ore material. Variations in lead isotopes are due to the radioactive decay of uranium in the ore. Likewise, neodymium isotopic abundances are skewed due to the radiogenic decay of samarium. Rubidium decay similarly alters the isotopic signature of strontium isotopic composition in ores. This paper will discuss the chemical processing of yellowcake performed at ORNL. Variations in lead, neodymium, and strontium isotopic abundances are being analyzed in UOC from two geologic sources. Chemical separation and instrumental protocols will be summarized. The data will be correlated with chemical signatures (such as elemental composition, uranium, carbon, and nitrogen isotopic content) to demonstrate the utility of principal component and cluster analyses to aid in the determination of UOC provenance.« less

Effect of neodymium:YAG laser capsulotomy on visual function in patients with posterior capsule opacification and good visual acuity.

PubMed

Yotsukura, Erisa; Torii, Hidemasa; Saiki, Megumi; Negishi, Kazuno; Tsubota, Kazuo

2016-03-01

To evaluate the effect of neodymium:YAG (Nd:YAG) laser capsulotomy on the visual function in patients with posterior capsule opacification (PCO) and good visual acuity. Keio University Hospital, Tokyo, Japan. Observational case series. Eyes were evaluated that had previous cataract surgery with a clinical diagnosis of PCO requiring Nd:YAG laser capsulotomy regardless of a good corrected distance visual acuity (CDVA) (at least 20/20). The CDVA, 10% low contrast visual acuity (LCVA), wavefront aberrations from the 3rd to 6th order, and retinal straylight were measured before and after Nd:YAG laser capsulotomy. The study included 16 eyes of 16 patients (10 men, 6 women; mean age 69.5 years ± 9.3 [SD]). The mean CDVA, LCVA, and straylight after Nd:YAG laser capsulotomy improved significantly (P < .05). The root mean square (RMS) of the 3rd Zernike coefficients (S3) and the RMS of the total higher-order aberrations (HOAs) from the 3rd to 6th order decreased significantly after capsulotomy (P < .05). The straylight correlated significantly with the total HOAs (r = 0.727, P = .002) and S3 (r = 0.748, P = .001) before capsulotomy. Subjective symptoms resolved after capsulotomy in all cases. Neodymium:YAG laser capsulotomy enabled a significant improvement in visual function even in patients with PCO with good visual acuity. Straylight measurements might be useful to determine the indications for Nd:YAG laser capsulotomy when patients report visual disturbances without decreased visual acuity. Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Method of making a light weight battery plaque

NASA Technical Reports Server (NTRS)

Reid, M. A.; Post, R. E.; Soltis, D. G. (Inventor)

1984-01-01

A nickel plaque which may be coated with a suitable metal or compound to make an electrode for a fuel cell or battery is fabricated by directing nickel sensitizer, catalyst and plating solutions through a porous plastic substrate in the order named and at prescribed temperatures and flow rates. A boride compound dissolved in the plating solution decreases the electrical resistance of the plaque. Certain substrates may require treatment in an alkali solution to dissolve filler materials thereby increasing porosity to a required 65%.

Development of a method for fabricating metallic matrix composite shapes by a continuous mechanical process

NASA Technical Reports Server (NTRS)

Divecha, A. P.

1974-01-01

Attempts made to develop processes capable of producing metal composites in structural shapes and sizes suitable for space applications are described. The processes must be continuous and promise to lower fabrication costs. Special attention was given to the aluminum boride (Al/b) composite system. Results show that despite adequate temperature control, the consolidation characteristics did not improve as expected. Inadequate binder removal was identified as the cause responsible. An Al/c (aluminum-graphite) composite was also examined.

Identification of thermodynamically stable ceramic reinforcement materials for iron aluminide matrices

NASA Technical Reports Server (NTRS)

Misra, Ajay K.

1990-01-01

Aluminide-base intermetallic matrix composites are currently being considered as potential high-temperature materials. One of the key factors in the selection of a reinforcement material is its chemical stability in the matrix. In this study, chemical interactions between iron aluminides and several potential reinforcement materials, which include carbides, oxides, borides, and nitrides, are analyzed from thermodynamic considerations. Several chemically compatible reinforcement materials are identified for the iron aluminides with Al concentrations ranging from 40 to 50 at. pct.

The Physics and Chemistry of carbides, Nitrides and Borides. Volume 185

DTIC Science & Technology

1990-01-01

and C-B-C chains [15,17]. Clearly, the use of boron-rich solids as electronic materials will place new demands on the quality of materials. In this...first heated in a pyrolytic boron nitride (PBN) crucible ( Union Carbide Corp.) under high vacuum (< 50 mTorr) to 1900°C. This removed surface...contamination of the sample. The powders were loaded into a graphite die with a high-purity BN die liner ( Union Carbide Grade HBC) with inner diameter of 3/8

Alumina-based ceramic composite

DOEpatents

Alexander, K.B.; Tiegs, T.N.; Becher, P.F.; Waters, S.B.

1996-07-23

An improved ceramic composite comprising oxide ceramic particulates, nonoxide ceramic particulates selected from the group consisting of carbides, borides, nitrides of silicon and transition metals and mixtures thereof, and a ductile binder selected from the group consisting of metallic, intermetallic alloys and mixtures thereof is described. The ceramic composite is made by blending powders of the ceramic particulates and the ductile to form a mixture and consolidating the mixture of under conditions of temperature and pressure sufficient to produce a densified ceramic composite. 5 figs.

Anti-scratch AlMgB14 Gorilla® Glass coating

NASA Astrophysics Data System (ADS)

Putrolaynen, V. V.; Grishin, A. M.; Rigoev, I. V.

2017-10-01

Hard aluminum-magnesium boride (BAM) films were fabricated onto Corning® Gorilla® Glass by radio-frequency magnetron sputtering of a single stoichiometric AlMgB14 target. BAM films exhibit a Vickers hardness from 10 to 30 GPa and a Young's modulus from 80 to 160 GPa depending on applied loading forces. Deposited hard coating increases the critical load at which glass substrate cracks. The adhesion energy of BAM films on Gorilla® Glass is 6.4 J/m2.

Synthesis and properties of nickel cobalt boron nanoparticles

NASA Astrophysics Data System (ADS)

Patel, J.; Pankhurst, Q. A.; Parkin, I. P.

2005-01-01

Amorphous cobalt nickel boride nanoparticles were synthesised by chemical reduction synthesis in aqueous solution. Careful control of synthesis conditions and post reaction oxidation enabled the nanoparticles to be converted into a core-shell structure comprising of an amorphous Co-Ni-B core and an outer metal oxide sheet. These particles had interesting magnetic properties including saturation magnetisations and coercivities of the order of 80 emu/g and 170 Oe respectively, making them suitable for a potential use as an exchange-pinned magnetic material.

Do Atoms Really "Emit" Absorption Lines?

ERIC Educational Resources Information Center

Brecher, Kenneth

1991-01-01

Presents three absorption line sources that enhance student understanding of the phenomena associated with the interaction of light with matter and help dispel the misconception that atoms "emit" absorption lines. Sources include neodymium, food coloring and other common household liquids, and fluorescent materials. (MDH)

Anterior capsule relaxing incisions with neodymium:YAG laser for patients at high-risk for anterior capsule contraction.

PubMed

Hayashi, Ken; Yoshida, Motoaki; Hirata, Akira; Hayashi, Hideyuki

2011-01-01

To examine the effect of anterior capsule relaxing incisions created with a neodymium:YAG (Nd:YAG) laser on prevention of anterior capsule contraction after cataract surgery in high-risk patients. Hayashi Eye Hospital, Fukuoka, Japan. Randomized masked clinical trials. Patients at high risk for anterior capsule contraction had anterior capsule relaxing incisions in either eye 3 days postoperatively. The anterior capsule opening was measured using a Scheimpflug videophotography system (EAS-1000) immediately and 1, 3, and 6 months after capsulotomy, and the percentage reduction in area was calculated. The degree of intraocular lens (IOL) decentration and tilt, posterior capsule opacification (PCO), and other complications were also assessed. Of the 84 patients included, 30 had primary angle closure, 28 had pseudoexfoliation, and 26 had diabetic retinopathy. There was no significant difference in the mean opening area between fellow eyes at baseline. In patients with primary angle closure, the area was significantly greater and the percentage reduction in area was significantly less in the capsulotomy group than in the no-capsulotomy group (P≤.0428). In patients with pseudoexfoliation or diabetic retinopathy, the percentage reduction was significantly less in the capsulotomy group than in the no-capsulotomy group (P≤.0493), although there was no significant difference in area. No significant difference was found in IOL decentration or tilt, PCO, or incidence of other complications. Neodymium:YAG laser anterior capsule relaxing incisions in the early period after cataract surgery were effective in preventing anterior capsule contraction in high-risk patients and had no adverse effects. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Neodymium in the oceans: a global database, a regional comparison and implications for palaeoceanographic research

PubMed Central

Griffiths, Alexander M.; Lambelet, Myriam; Little, Susan H.; Stichel, Torben; Wilson, David J.

2016-01-01

The neodymium (Nd) isotopic composition of seawater has been used extensively to reconstruct ocean circulation on a variety of time scales. However, dissolved neodymium concentrations and isotopes do not always behave conservatively, and quantitative deconvolution of this non-conservative component can be used to detect trace metal inputs and isotopic exchange at ocean–sediment interfaces. In order to facilitate such comparisons for historical datasets, we here provide an extended global database for Nd isotopes and concentrations in the context of hydrography and nutrients. Since 2010, combined datasets for a large range of trace elements and isotopes are collected on international GEOTRACES section cruises, alongside classical nutrient and hydrography measurements. Here, we take a first step towards exploiting these datasets by comparing high-resolution Nd sections for the western and eastern North Atlantic in the context of hydrography, nutrients and aluminium (Al) concentrations. Evaluating those data in tracer–tracer space reveals that North Atlantic seawater Nd isotopes and concentrations generally follow the patterns of advection, as do Al concentrations. Deviations from water mass mixing are observed locally, associated with the addition or removal of trace metals in benthic nepheloid layers, exchange with ocean margins (i.e. boundary exchange) and/or exchange with particulate phases (i.e. reversible scavenging). We emphasize that the complexity of some of the new datasets cautions against a quantitative interpretation of individual palaeo Nd isotope records, and indicates the importance of spatial reconstructions for a more balanced approach to deciphering past ocean changes. This article is part of the themed issue ‘Biological and climatic impacts of ocean trace element chemistry’. PMID:29035258

Coherent response of Antarctic Intermediate Water and Atlantic Meridional Overturning Circulation during the last deglaciation: reconciling contrasting neodymium isotope reconstructions in tropical Atlantic

NASA Astrophysics Data System (ADS)

Gu, S.; Liu, Z.; Zhang, J.; Rempfer, J.; Joos, F.; Oppo, D.

2017-12-01

Antarctic Intermediate Water (AAIW) plays important roles in the global climate system and the global ocean nutrient and carbon cycles. However, it is unclear how AAIW responds to global climate changes. In particular, neodymium isotopic composition (ɛNd) reconstructions from different locations in tropical Atlantic, have led to a debate on the relationship between the northward penetration of AAIW into the tropical Atlantic and Atlantic Meridional Overturning Circulation (AMOC) variability during the last deglaciation. We resolve this controversy by studying the transient oceanic evolution during the last deglaciation using a neodymium-enabled ocean model. Our results suggest a coherent response of AAIW and AMOC: when AMOC weakens, the northward penetration and transport of AAIW decreases while its depth and thickness increase. Our study highlights that as part of the return flow of the North Atlantic Deep Water (NADW), the northward penetration of AAIW in Atlantic is determined predominately by AMOC intensity. Moreover, the inconsistency among different tropical Atlantic ɛNd reconstructions is reconciled by considering their corresponding core locations and depths, which were influenced by different water masses and ocean currents in the past. The very radiogenic water from the bottom of the Gulf of Mexico and Caribbean Sea, which was previously overlooked in interpretations of deglacial ɛNd variability, can be transported to shallow layers during active AMOC, and modulates ɛNd in the tropical Atlantic. Changes in the AAIW core depth must also be considered. Thus, interpretation of ɛNd reconstructions from the tropical Atlantic is more complicated than suggested in previous studies. ­­

Systematic variation of rare earths in monazite

USGS Publications Warehouse

Murata, K.J.; Rose, H.J.; Carron, M.K.

1953-01-01

Ten monazites from widely scattered localities have been analyzed for La, Ce, Pr, Nd, Sm, Gd, Y and Th by means of a combined chemical and emission spectrographic method. The analytical results, calculated to atomic percent of total rare earths (thorium excluded), show a considerable variation in the proportions of every element except praseodymium, which is relatively constant. The general variation trends of the elements may be calculated by assuming that the monazites represent different stages in a fractional precipitation process, and by assuming that there is a gradational increase in the precipitability of rare earth elements with decreasing ionic radius. Fractional precipitation brings about an increase in lanthanum and cerium, little change in praseodymium, and a decrease in neodymium, samarium, gadolinium, and yttrium. Deviations from the calculated lines of variation consist of a simultaneous, abnormal increase or decrease in the proportions of cerium, praseodymium, and neodymium with antipathetic decrease or increase in the proportions of the other elements. These deviations are ascribed to abnormally high or low temperatures that affect the precipitability of the central trio of elements (Ce, Pr, Nd) relatively more than that of the other elements. The following semiquantitative rules have been found useful in describing the composition of rare earths from monazite: 1. 1. The sum of lanthanum and neodymium is very nearly a constant at 42 ?? 2 atomic percent. 2. 2. Praseodymium is very nearly constant at 5 ?? 1 atomic percent. 3. 3. The sum of Ce, Sm, Gd, and Y is very nearly a constant at 53 ?? 3 atomic percent. No correlation could be established between the content of Th and that of any of the rare earth elements. ?? 1953.

Electrochemical immunoassay for vitellogenin based on sequential injection using antigen-immobilized magnetic microbeads.

PubMed

Hirakawa, Koji; Katayama, Masaaki; Soh, Nobuaki; Nakano, Koji; Imato, Toshihiko

2006-01-01

A rapid and sensitive immunoassay for the determination of vitellogenin (Vg) is described. The method involves a sequential injection analysis (SIA) system equipped with an amperometric detector and a neodymium magnet. Magnetic beads, onto which an antigen (Vg) was immobilized, were used as a solid support in an immunoassay. The introduction, trapping and release of magnetic beads in an immunoreaction cell were controlled by means of the neodymium magnet and by adjusting the flow of the carrier solution. The immunoassay was based on an indirect competitive immunoreaction of an alkaline phosphatase (ALP) labeled anti-Vg monoclonal antibody between the fraction of Vg immobilized on the magnetic beads and Vg in the sample solution. The immobilization of Vg on the beads involved coupling an amino group moiety of Vg with the magnetic beads after activation of a carboxylate moiety on the surface of magnetic beads that had been coated with a polylactate film. The Vg-immobilized magnetic beads were introduced and trapped in the immunoreaction cell equipped with the neodymium magnet; a Vg sample solution containing an ALP labeled anti-Vg antibody at a constant concentration and a p-aminophenyl phosphate (PAPP) solution were sequentially introduced into the immunoreaction cell. The product of the enzyme reaction of PAPP with ALP on the antibody, paminophenol, was transported to an amperometric detector, the applied voltage of which was set at +0.2 V vs. an Ag/AgCl reference electrode. A sigmoid calibration curve was obtained when the logarithm of the concentration of Vg was plotted against the peak current of the amperometric detector using various concentrations of standard Vg sample solutions (0-500 ppb). The time required for the analysis is less than 15 min.

Features of surface phase formation during case-hardening of iron- and titanium-based alloys

NASA Astrophysics Data System (ADS)

Vintaikin, B. E.; Kamynin, A. V.; Kraposhin, V. S.; Smirnov, A. E.; Terezanova, K. V.; Cherenkova, S. A.; Sheykina, V. I.

2017-11-01

The article provides a detailed analysis of formation features for surface phases in technical iron and Cr20-Ni80 alloy samples that undergo case-hardening at a temperature of 850°C for 2, 4 and 6 hours of saturation in two different environments: acetylene, and molten salt consisting of sodium tetraborate and amorphous boron. We carried out an X-ray phase analysis to determine the phase structure of surface material layers that formed as a result of the case-hardening process. We discovered that after carburising it was possible to detect Fe3C and Fe-α phases on the surface of technical iron samples, and after boriding we found FeB, Fe2B and Fe3B phases; we noted a lack of characteristic Fe-α and Fe-γ peaks on the X-ray diffraction pattern. We detected many different phases in the Cr20-Ni80 alloy after the same type of case-hardening. Titanium oxides appeared after case-hardening of titanium in air at 800°C. We provide data on surface structure of samples subjected to vacuum carburising: over a 2 to 6 hour interval, the layer thickness is a parabolic function of time. When carrying out electrolysis-free liquid boriding, increasing exposure time from 2 to 6 hours alters the thickness of the strengthened layer only slightly, so, when carrying out case-hardening, it is less efficient to increase saturation time in molten salt containing sodium tetraborate and amorphous boron.

Role of atomic bonding for compound and glass formation in Ni-Si, Pd-Si, and Ni-B systems

NASA Astrophysics Data System (ADS)

Tanaka, K.; Saito, T.; Suzuki, K.; Hasegawa, R.

1985-11-01

Valence electronic structures of crystalline compounds and glassy alloys of Ni silicides, Pd silicides, and Ni borides are studied by soft-x-ray spectroscopy over wide ranges of Si and B concentrations. The samples prepared include bulk compounds, glassy ribbons, and amorphous sputtered films. Silicon Kβ emissions of Ni and Pd silicides generally consist of a prominent peak fixed at ~=4.5 and ~=5.8 eV below the Fermi level EF, respectively, with a shoulder near EF which grows and shifts toward lower energy with increasing Si concentration. The former is identified as due to Si p-like states forming Si 3p-Ni 3d or Si 3p-Pd 4d bonding states while the latter as due to the corresponding antibonding states. Ni L3 and Pd L3 emissions of these silicides indicate that Ni 3d and Pd 4d states lie between the above two states. These local electronic configurations are consistent with partial-density-of-states (PDOS) calculations performed by Bisi and Calandra. Similar electronic configurations are suggested for Ni borides from B Kα and Ni L3 emissions. Differences of emission spectra between compounds and glasses of similar compositions are rather small, but some enhancement of the contribution of antibonding states to the PDOS near EF is suggested for certain glasses over that of the corresponding compounds. These features are discussed in connection with the compound stability and glass formability.

Effect Of Neodymium Substitution In Structural Characteristics Of Magnesium Ferrite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thankachan, Smitha; Binu, P. J.; Xavier, Sheena

2011-10-20

The effect of Nd{sup 3+} substitution on the structural properties of Magnesium ferrite was studied in the series MgNd{sub x}Fe{sub 2-x}O{sub 4}, where x = 0 to 0.3 in steps of 0.05. The series was prepared by sol-gel technique which is one of the novel technique to prepare nanosized samples. Structural characterization was done using X-ray diffractometer and Fourier Transform Infrared Spectrometer. XRD analysis reveals the prepared samples are single phasic till x = 0.2. From x0 = .25, a secondary phase of iron neodymium oxide appears along with the spinel phase. Particle size calculation shows the prepared samples aremore » in the 9nm to 11 nm regime. Lattice parameter was found to increase with concentration of Nd. XRD and FTIR analysis confirmed spinel structure of the prepared samples. XRF result shows the expected composition of prepared samples. The frequency dependence of the dielectric constant in the range 100 Hz--120MHz was also studied« less

Power scaling of diode-pumped neodymium yttrium aluminum borate laser

NASA Technical Reports Server (NTRS)

Hemmati, Hamid

1991-01-01

Preliminary results are presented of the efficient diode-pumped operation of a neodymium yttrium aluminum borate (NYAB) laser at 531.5 nm using two 1-W diode-laser arrays for the pump. With 1380 mW of CW power incident on the crystal, as much as 51 mW of 532.5-nm laser radiation was obtained with the unoptimized cavity. The corresponding optical-to-optical conversion efficiency was 3.7 percent. A plot of the output 531.5 nm vs incident 807 nm pump power is shown. The crystal output power was critically dependent on the rotational and translational adjustment of the NYAB crystal inside the cavity. It is suggested that a crystal cut at the exact phase matching angle, placed in a cavity with proper optimal reflection and transmission mirror coatings, and pumped at proper wavelength can result in higher output power. Thus, the NYAB output power approaches that of a CW intracavity frequency doubled Nd:YAG laser.

An experimental approach in revisiting the magnetic orientation of cattle.

PubMed

Weijers, Debby; Hemerik, Lia; Heitkönig, Ignas M A

2018-01-01

In response to the increasing number of observational studies on an apparent south-north orientation in non-homing, non-migrating terrestrial mammals, we experimentally tested the alignment hypothesis using strong neodymium magnets on the resting orientation of individual cattle in Portugal. Contrary to the hypothesis, the 34 cows in the experiment showed no directional preference, neither with, nor without a strong neodymium magnet fixed to their collar. The concurrently performed 2,428 daytime observations-excluding the hottest part of the day-of 659 resting individual cattle did not show a south-north alignment when at rest either. The preferred compass orientation of these cows was on average 130 degrees from the magnetic north (i.e., south east). Cow compass orientation correlated significantly with sun direction, but not with wind direction. In as far as we can determine, this is the first experimental test on magnetic orientation in larger, non-homing, non-migrating mammals. These experimental and observational findings do not support previously published suggestions on the magnetic south-north alignment in these mammals.

Rapid neodymium release to marine waters from lithogenic sediments in the Amazon estuary

PubMed Central

Rousseau, Tristan C. C.; Sonke, Jeroen E.; Chmeleff, Jérôme; van Beek, Pieter; Souhaut, Marc; Boaventura, Geraldo; Seyler, Patrick; Jeandel, Catherine

2015-01-01

Rare earth element (REE) concentrations and neodymium isotopic composition (ɛNd) are tracers for ocean circulation and biogeochemistry. Although models suggest that REE release from lithogenic sediment in river discharge may dominate all other REE inputs to the oceans, the occurrence, mechanisms and magnitude of such a source are still debated. Here we present the first simultaneous observations of dissolved (<0.45 μm), colloidal and particulate REE and ɛNd in the Amazon estuary. A sharp drop in dissolved REE in the low-salinity zone is driven by coagulation of colloidal matter. At mid-salinities, total dissolved REE levels slightly increase, while ɛNd values are shifted from the dissolved Nd river endmember (−8.9) to values typical of river suspended matter (−10.6). Combining a Nd isotope mass balance with apparent radium isotope ages of estuarine waters suggests a rapid (3 weeks) and globally significant Nd release by dissolution of lithogenic suspended sediments. PMID:26158849

Picosecond 532-nm neodymium-doped yttrium aluminium garnet laser-a novel and promising modality for the treatment of café-au-lait macules.

PubMed

Artzi, Ofir; Mehrabi, Joseph N; Koren, Amir; Niv, Roni; Lapidoth, Moshe; Levi, Assi

2018-05-01

Café-au-lait macules (CALMs) present as benign hyperpigmented, well-circumscribed spots on the skin for which many patients seek treatment for aesthetic reasons. The objective of this study is to report our experience in treating CALMs using a picosecond 532-nm neodymium-doped yttrium aluminium garnet (PS 532 nm) laser. This is a retrospective case series of 16 patients with CALMs who were treated by a PS 532-nm laser (1-4 treatments, 4-8 weeks apart). Response as seen on clinical photographs was assessed by two independent dermatologists and graded on a scale of 0 (exacerbation) to 5 (95-100% improvement). Patient satisfaction and tolerance were documented at final visit. The results of 15 patients demonstrated significant improvement (average 3.43), and their satisfaction and tolerance levels were high. One patient had no response whatsoever to treatment. The PS 532-nm laser is a promising novel modality for the treatment of CALMs.

Treatment of pseudofolliculitis barbae in very dark skin with a long pulse Nd:YAG laser.

PubMed Central

Ross, E. Victor; Cooke, Linda M.; Overstreet, Kristen A.; Buttolph, Greg D.; Blair, Mark A.

2002-01-01

BACKGROUND: Pseudofolliculitis barbae affects some individuals with coarse curly hair. Currently available treatment modalities are often ineffective. In some studies, lasers have been shown to be potentially helpful in mitigating disease severity by reducing the number and/or thickness of hair shafts. METHODS: This was a side-by-side interventional study conducted at a military tertiary medical facility. The study group included 26 patients (skin types IV, V, and VI) referred from primary care physicians with a diagnosis of pseudofolliculitis barbae refractory to medical therapy. A neodymium YAG laser was used to treat one half of the neck. One month later, shaving bumps were counted and compared to their preoperative levels on both sides. RESULTS: Mean postoperative papule counts were 11.6 +/- 6 (SD) and 30.1 +/- 19 (SD) on the treated side and untreated sides, respectively. CONCLUSION: Neodymium YAG laser treatment represents a safe and effective option for reducing papule formation in patients with pseudofolliculitis barbae. Images Figure 1 PMID:12408693

Analysis of a 10 megawatt space-based solar-pumped neodymium laser system

NASA Technical Reports Server (NTRS)

Kurweg, U. H.

1984-01-01

A ten megawatt solar-pumped continuous liquid laser system for space applications is examined. It is found that a single inflatable mirror of 434 m diameter used in conjunction with a conical secondary concentrator is sufficient to side pump a liquid neodymium lasant in an annular tube of 6 m length and 1 m outer and 0.8 m inner diameter. About one fourth of intercepted radiation converging on the laser tube is absorbed and one fifth of this radiation is effective in populating the upper levels. The liquid lasant is flowed through the annular laser cavity at 1.9 m/s and is cooled via a heat exchanger and a large radiator surface comparable in size to the concentrating mirror. The power density of incident light within the lasant of approximately 68 watt/cu cm required for cw operation is exceeded in the present annular configuration. Total system weight corresponds to 20,500 kg and is thus capable of being transported to near Earth orbit by a single shuttle flight.

Framework for resilience in material supply chains, with a case study from the 2010 Rare Earth Crisis.

PubMed

Sprecher, Benjamin; Daigo, Ichiro; Murakami, Shinsuke; Kleijn, Rene; Vos, Matthijs; Kramer, Gert Jan

2015-06-02

In 2010, Chinese export restrictions caused the price of the rare earth element neodymium to increase by a factor of 10, only to return to almost normal levels in the following months. This despite the fact that the restrictions were not lifted. The significant price peak shows that this material supply chain was only weakly resistant to a major supply disruption. However, the fact that prices rapidly returned to lower levels implies a certain resilience. With the help of a novel approach, based on resilience theory combined with a material flow analysis (MFA) based representation of the neodymium magnet (NdFeB) supply chain, we show that supply chain resilience is composed of various mechanisms, including (a) resistance, (b) rapidity, and (c) flexibility, that originate from different parts of the supply chain. We make recommendations to improve the capacity of the NdFeB system to deal with future disruptions and discuss potential generalities for the resilience of other material supply chains.

Influence of neodymium concentration on excitation and emission properties of Nd doped gallium oxide nanocrystalline films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Podhorodecki, A.; Banski, M.; Misiewicz, J.

Gallium oxide and more particularly {beta}-Ga{sub 2}O{sub 3} matrix is an excellent material for new generation of devices electrically or optically driven as it is known as the widest band gap transparent conductive oxide. In this paper, the optical properties of neodymium doped gallium oxide films grown by magnetron sputtering have been analyzed. The influence of the Nd ions concentration on the excitation/emission mechanisms of Nd ions and the role of gallium oxide matrix have been investigated. The grain size reduction into gallium oxide films have been observed when concentration of Nd increases. It has been found for all samplesmore » that the charge transfer is the main excitation mechanism for Nd ions where defect states play an important role as intermediate states. As a consequence Nd emission efficiency increases with temperature giving rise to most intensive emission at 1087 nm at room temperature.« less

CIE colorimetric system fails to calculate the chroma of a Nd:YAG crystal under the fluorescent illuminant F7

NASA Astrophysics Data System (ADS)

Liu, Yan; Chen, Qinghan; Bu, Xianhui; Feng, Pingyun

2002-06-01

The rare earth element neodymium doped yttrium aluminum garnet (Nd:YAG) is a laser crystal widely used for producing laser in the infrared range. Neodymium causes many characteristic absorption peaks in the transmittance spectrum of the Nd:YAG crystal in the visible range. The crystal appears pink under daylight and incandescent light, and colorless under fluorescent light. The colorimetric calculation results of chroma under the CIE standard fluorescent illuminant F7 do not agree with the color appearance under fluorescent light. The calculated chroma values should be near zero to agree with a colorless appearance, but it is actually 11.79 in the CIELAB color space. This failure of the colorimetric calculation is caused by the color matching functions of the CIE colorimetric observers. The color matching functions do not agree with the spectral sensitivity curves of the human eye, especially the x(λ) function does not matches the spectral sensitivity curve of the long wavelength cone photoreceptors.

Chemical precursors to non-oxide ceramics: Macro to nanoscale materials

NASA Astrophysics Data System (ADS)

Forsthoefel, Kersten M.

Non-oxide ceramics exhibit a number of important properties that make them ideal for technologically important applications (thermal and chemical stability, high strength and hardness, wear-resistance, light weight, and a range of electronic and optical properties). Unfortunately, traditional methodologies to these types of materials are limited to fairly simple shapes and complex processed forms cannot be attained through these methods. The establishment of the polymeric precursor approach has allowed for the generation of advanced materials, such as refractory non-oxide ceramics, with controlled compositions, under moderate conditions, and in processed forms. The goal of the work described in this dissertation was both to develop new processible precursors to technologically important ceramics and to achieve the formation of advanced materials in processed forms. One aspect of this research exploited previously developed preceramic precursors to boron carbide, boron nitride and silicon carbide for the generation of a wide variety of advanced materials: (1) ultra-high temperature ceramic (UHTC) structural materials composed of hafnium boride and related composite materials, (2) the quaternary borocarbide superconductors, and (3) on the nanoscale, non-oxide ceramic nanotubules. The generation of the UHTC and the quaternary borocarbide materials was achieved through a method that employs a processible polymer/metal(s) dispersion followed by subsequent pyrolyses. In the case of the UHTC, hafnium oxide, hafnium, or hafnium boride powders were dispersed in a suitable precursor to afford hafnium borides or related composite materials (HfB2/HfC, HfB2/HfN, HfB2/SiC) in high yields and purities. The quaternary borocarbide superconducting materials were produced from pyrolyses of dispersions containing appropriate stoichiometric amounts of transition metal, lanthanide metal, and the polyhexenyldecaborane polymer. Both chemical vapor deposition (CVD) based routes employing a molecular precursor and porous alumina templating routes paired with solution-based methodologies are shown to generate non-oxide ceramic nanotubules of boron carbide, boron nitride and silicon carbide compositions. In the final phase of this work, a new metal-catalyzed route to poly(1-alkenyl- o-carborane) homopolymers and related copolymers was developed. Both homopolymers of 1-alkenyl-o-carboranes (1-vinyl-, 1-butenyl-, 1-hexenyl-) and copolymers of 1-hexenyl-o-carborane and allyltrimethylsilane or 1-hexenyl-o-carborane and 6-hexenyldecaborane were synthesized via the Cp2ZrMe2/B(C6F5) 3 catalyst system. A copolymer containing 1-hexenyl-o-carborane and the cross-linking agent, 6-hexenyldecaborane, was synthetically designed which exhibits initial cross-linking at ˜250°C and then converts in 75% yields to boron carbide at 1250°C.

LASER PLASMA: Experimental confirmation of the erosion origin of pulsed low-threshold surface optical breakdown of air

NASA Astrophysics Data System (ADS)

Min'ko, L. Ya; Chumakou, A. N.; Chivel', Yu A.

1988-08-01

Nanosecond kinetic spectroscopy techniques were used to identify the erosion origin of pulsed low-threshold surface optical breakdown of air as a result of interaction of microsecond neodymium and CO2 laser pulses with some metals (indium, lead).

Spectroscopic Properties of Neodymium and Erbium-Doped Magnesium Oxide Ceramics

DTIC Science & Technology

2015-09-01

may contribute to the difference between the measured and expected values (such as varied hydration levels in the starting materials), there has...believe that such impurities forms from the thermal decomposition of the organic binders and dispersants used in the processing. We believe the

Science Can Be Attractive.

ERIC Educational Resources Information Center

Leyden, Michael B.

1994-01-01

Discusses the properties of neodymium magnets and magnets in general and how magnets can be used to teach students important scientific principles, such as attraction, repulsion, and polarity; the role of magnetic forces in electronic communications and computers; the magnetic properties of the earth and compasses; and the relationship between…

Perovskite catalysts for oxidative coupling

DOEpatents

Campbell, K.D.

1991-06-25

Perovskites of the structure A[sub 2]B[sub 2]C[sub 3]O[sub 10] are useful as catalysts for the oxidative coupling of lower alkane to heavier hydrocarbons. A is alkali metal; B is lanthanide or lanthanum, cerium, neodymium, samarium, praseodymium, gadolinium or dysprosium; and C is titanium.

Perovskite catalysts for oxidative coupling

DOEpatents

Campbell, Kenneth D.

1991-01-01

Perovskites of the structure A.sub.2 B.sub.2 C.sub.3 O.sub.10 are useful as catalysts for the oxidative coupling of lower alkane to heavier hydrocarbons. A is alkali metal; B is lanthanide or lanthanum, cerium, neodymium, samarium, praseodymium, gadolinium or dysprosium; and C is titanium.

Temperature dependence of the 1.06-microm stimulated emission cross section of neodymium in YAG and in GSGG.

PubMed

Rapaport, Alexandra; Zhao, Shengzhi; Xiao, Guohua; Howard, Andrew; Bass, Michael

2002-11-20

A linear temperature dependence between -70 degrees C and +70 degrees C is reported for the peak stimulated emission cross section of Nd3+ ions in both yttrium aluminum garnet (YAG) and gadolinium scandium gallium garnet (GSGG).

Neodymium Isotope Variations in Late Quaternary Carbonate Lake Sediments, Owens Valley, Eastern California.

NASA Astrophysics Data System (ADS)

Minervini, J. M.; Stewart, B. W.

2001-12-01

Owens Lake is situated in a mostly-closed basin fed by water and sediments derived primarily from the eastern Sierra Nevada range. Chemical and sedimentological variations in USGS Owens Lake Core OL-92, which extends back 800 ka, have been shown to be sensitive tracers of Great Basin paleoclimate. Here we report preliminary neodymium (Nd) isotope data from core OL-92 to investigate sediment provenance, the chemical behavior of rare earth elements (REE) in non-marine systems, and possible climate-related shifts in weathering patterns of the eastern Sierra Nevada during the last glacial-interglacial transition. Neodymium isotopic analyses were carried out on the carbonate fraction of sediment samples ranging in age from 16.8 to 6.9 ka from Owens Lake core OL-92. Samples were treated with ammonium acetate to remove exchangeable cations from coexisting silicate material, and subsequently leached with 8% acetic acid to dissolve carbonate minerals. Based on the mass of sediment leached with acetic acid, the fraction of carbonate (relative to clastic silicate material) increases from 6.6 to 66.5% over the 10 ka period represented by these samples. This increase in carbonate reflects desiccation of the Owens Lake basin; as streamwater flow is reduced, the lake spends a greater proportion of its time saturated in carbonate minerals, and clastic input might also be reduced. Concentrations of Nd in Owens Lake carbonate range from 7 to 170 ppm, values that are 2-1000 times higher than marine planktonic foraminifera (e.g., Vance and Burton, 1999, EPSL 173, 365). In general, high concentrations of Nd in Owens Lake carbonate are associated with older sediment samples with lower carbonate fractions. The decrease in Nd concentration over this time period could be a result of extraction of Nd from lake waters by precipitation of carbonate as desiccation proceeded. Epsilon-Nd values of Owens Lake carbonate range from -5.3 to -6.5, and are consistent with eastern Sierra Nevada granitic bedrock values. A slight shift from higher to lower epsilon-Nd values occurs between about 14 and 9 ka, and could be due to variations in sediment source regions associated with the retreat of alpine glaciers along the eastern flank of the Sierra Nevada. With ongoing studies to assess the relationship between clastic and carbonate sources, neodymium isotope data can potentially provide detailed information about the relationship between chemical and mechanical weathering processes in a well-constrained continental setting.

Method For Synthesizing Extremely High-Temperature Melting Materials

DOEpatents

Saboungi, Marie-Louise; Glorieux, Benoit

2005-11-22

The invention relates to a method of synthesizing high-temperature melting materials. More specifically the invention relates to a containerless method of synthesizing very high temperature melting materials such as borides, carbides and transition-metal, lanthanide and actinide oxides, using an Aerodynamic Levitator and a laser. The object of the invention is to provide a method for synthesizing extremely high-temperature melting materials that are otherwise difficult to produce, without the use of containers, allowing the manipulation of the phase (amorphous/crystalline/metastable) and permitting changes of the environment such as different gaseous compositions.

Preparation of actinide boride materials via solid-state metathesis reactions and actinide dicarbollide precursors

NASA Astrophysics Data System (ADS)

Lupinetti, Anthony J.; Fife, Julie; Garcia, Eduardo; Abney, Kent D.

2000-07-01

Information gaps exist in the knowledge base needed for choosing among the alternate processes to be used in the safe conversion of fissile materials to optimal forms for safe interim storage, long-term storage, and ultimate disposition. The current baseline storage technology for various wastes uses borosilicate glasses.1 The focus of this paper is the synthesis of actinide-containing ceramic materials at low and moderate temperatures (200 °C-1000 °C) using molecular and polymeric actinide borane and carborane complexes.

Corrosion of Ceramic Materials

NASA Technical Reports Server (NTRS)

Opila, Elizabeth J.; Jacobson, Nathan S.

1999-01-01

Non-oxide ceramics are promising materials for a range of high temperature applications. Selected current and future applications are listed. In all such applications, the ceramics are exposed to high temperature gases. Therefore it is critical to understand the response of these materials to their environment. The variables to be considered here include both the type of ceramic and the environment to which it is exposed. Non-oxide ceramics include borides, nitrides, and carbides. Most high temperature corrosion environments contain oxygen and hence the emphasis of this chapter will be on oxidation processes.

Reactive multilayer synthesis of hard ceramic foils and films

DOEpatents

Makowiecki, Daniel M.; Holt, Joseph B.

1996-01-01

A method for synthesizing hard ceramic materials such as carbides, borides nd aluminides, particularly in the form of coatings provided on another material so as to improve the wear and abrasion performance of machine tools, for example. The method involves the sputter deposition of alternating layers of reactive metals with layers of carbon, boron, or aluminum and the subsequent reaction of the multilayered structure to produce a dense crystalline ceramic. The material can be coated on a substrate or formed as a foil which can be coild as a tape for later use.

High temperature solar energy absorbing surfaces

DOEpatents

Schreyer, J.M.; Schmitt, C.R.; Abbatiello, L.A.

A solar collector having an improved coating is provided. The coating is a plasma-sprayed coating comprising a material having a melting point above 500/sup 0/C at which it is stable and selected from the group of boron carbide, boron nitride, metals and metal oxides, nitrides, carbides, borides, and silicates. The coatings preferably have a porosity of about 15 to 25% and a thickness of less than 200 micrometers. The coatings can be provided by plasma-spraying particles having a mean diameter of about 10 to 200 micrometers.

Fundamental Thermal and Mechanical Properties of Boride Ceramics

DTIC Science & Technology

2014-02-28

Zr ,Y)B2 ( Zr ,Hf)B2 ( Zr ,Ti)B2 ZrB2 El ec tri ca l R es is tiv ity (µ Ω -c m ) Temperature (°C) Figure 17. Electrical resistivity as a function...family as Zr , namely Ti and Hf, had minimal effect on thermal conductivity, while others such as Nb , Ta, and W had an increasing impact based on their...diffusivity (α), heat capacity (Cp) from the NIST-JANAF tables, and bulk density (ρ) using Equation 6. (5) (6) Electrical resistivity

Method for Synthesizing Extremeley High Temperature Melting Materials

DOEpatents

Saboungi, Marie-Louise and Glorieux, Benoit

2005-11-22

The invention relates to a method of synthesizing high-temperature melting materials. More specifically the invention relates to a containerless method of synthesizing very high temperature melting materials such as borides, carbides and transition-metal, lanthanide and actinide oxides, using an Aerodynamic Levitator and a laser. The object of the invention is to provide a method for synthesizing extremely high-temperature melting materials that are otherwise difficult to produce, without the use of containers, allowing the manipulation of the phase (amorphous/crystalline/metastable) and permitting changes of the environment such as different gaseous compositions.

Thermodynamic analysis of chemical compatibility of several reinforcement materials with niobium aluminides

NASA Technical Reports Server (NTRS)

Misra, Ajay K.

1989-01-01

Chemical compatibility of several reinforcement materials with three niobium aluminides, Nb3Al, Nb2Al, and NbAl3, were examined from thermodynamic considerations. The reinforcement materials considered in this study include carbides, borides, nitrides, oxides, silicides, and Engel-Brewer compounds. Thermodynamics of the Nb-Al system were reviewed and activities of Nb and Al were derived at desired calculation temperatures. Criteria for chemical compatibility between the reinforcement material and Nb-Al compounds have been defined and several chemically compatible reinforcement materials have been identified.

Ultra-hard AlMgB14 coatings fabricated by RF magnetron sputtering from a stoichiometric target

NASA Astrophysics Data System (ADS)

Grishin, A. M.; Khartsev, S. I.; Böhlmark, J.; Ahlgren, M.

2015-01-01

For the first time hard aluminum magnesium boride films were fabricated by RF magnetron sputtering from a single stoichiometric ceramic AlMgB14 target. Optimized processing conditions (substrate temperature, target sputtering power and target-to-substrate distance) enable fabrication of stoichiometric in-depth compositionally homogeneous films with the peak values of nanohardness 88 GPa and Young's modulus 517 GPa at the penetration depth of 26 nm and, respectively, 35 and 275 GPa at 200 nm depth in 2 μm thick film.

Foreword

NASA Astrophysics Data System (ADS)

Manghnani, Murli H.

2015-09-01

The 18th International Symposium on Boron, Borides and Related Materials was held in Hawaii Prince Hotel Waikiki, Honolulu, Hawaii, USA on August 31 to September 5, 2014 (ISBB 2014). A booklet of the Program and Abstracts prepared for the Symposium served as an important record of the scientific papers presented as oral paper (68) and as posters (53). The wide range of contributions in various areas of inter-disciplinary research in boron-related materials, and the discussions during the sessions, demonstrated impressive advancements and offer many future opportunities for individual as well as collaborative endeavors globally.

Interactions between exogenous rare earth elements and phosphorus leaching in packed soil columns

USDA-ARS?s Scientific Manuscript database

Rare earth elements (REEs) increasingly used in agriculture as an amendment for crop growth may help to lessen environmental losses of phosphorus (P) from heavily fertilized soils. The vertical transport characteristics of P and REEs, lanthanum (La), neodymium (Nd), samarium (Sm), and cerium (Ce), w...

Feasibility of atomic and molecular laser induced breakdown spectroscopy (LIBS) to in-situ determination of chlorine in concrete : final report.

DOT National Transportation Integrated Search

2016-10-01

Laser-induced breakdown spectroscopy (LIBS) has been studied as a fast method of detecting chlorine in concrete samples. Both single pulse (SP) and double pulse (DP) experiments have been tested. Several combinations of lasers (Neodymium-Yttrium Alum...

Cladding For Transversely-Pumped Laser Rod

NASA Technical Reports Server (NTRS)

Byer, Robert L.; Fan, Tso Yee

1989-01-01

Combination of suitable dimensioning and cladding of neodymium:yttrium aluminum garnet of similar solid-state laser provides for more efficient utilization of transversely-incident pump light from diode lasers. New design overcomes some of limitations of longitudinal- and older transverse-pumping concepts and promotes operation at higher output powers in TEM00 mode.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hossain, M. Anwar; Center for Crystal Science and Technology, University of Yamanashi, Miyamae 7-32, Kofu, Yamanashi 400-8511; Tanaka, Isao

We studied thermoelectric properties of YB{sub 41}Si{sub 1.3} single crystals grown by the floating zone method. The composition of the grown crystal was confirmed by electron probe micro-analysis. We have determined the growth direction for the first time for these borosilicides, and discovered relatively large anisotropy in electrical properties. We measured the electrical resistivity and Seebeck coefficient along [510] (the growth direction) and [052] directions and we found that this crystal exhibits strong electrical anisotropy with a maximum of more than 8 times. An interesting layered structural feature is revealed along [510] with dense boron cluster layers and yttrium layers,more » with conductivity enhanced along this direction. We obtained 3.6 times higher power factor along [510] compared to that along [052]. Although the ZT of the present system is low, anisotropy in the thermoelectric properties of a boride was reported for the first time, and can be a clue in developing other boride systems also. - Graphical abstract: The growth direction ([510]) was determined for the first time in YB{sub 41}Si{sub 1.3} single crystals and revealed an interesting layered feature of boron clusters and metal atoms, along which the electrical conductivity and thermoelectric power factor was strongly enhanced. - Highlights: • We have grown YB{sub 41}Si{sub 1.3} single crystals by the floating zone method. • Growth direction of [510] determined for first time in REB{sub 41}Si{sub 1.2}. • Electrical resistivity was strongly anisotropic with possible enhancement along metal layers. • The obtained power factor along [510] is 3.6 times higher than that along [052].« less

Boron oxynitride nanoclusters on tungsten trioxide as a metal-free cocatalyst for photocatalytic oxygen evolution from water splitting

NASA Astrophysics Data System (ADS)

Xie, Ying Peng; Liu, Gang; Lu, Gao Qing (Max); Cheng, Hui-Ming

2012-02-01

Here we show that B2O3-xNx nanoclusters can be formed on the surface of WO3 particles by a combination of thermal oxidation of tungsten boride (WB) in air and the subsequent nitriding process in gaseous ammonia. The resultant nanoclusters are found to play an apparent role in improving the photocatalytic oxygen evolution of WO3 by promoting the surface separation of photoexcited charge-carriers.Here we show that B2O3-xNx nanoclusters can be formed on the surface of WO3 particles by a combination of thermal oxidation of tungsten boride (WB) in air and the subsequent nitriding process in gaseous ammonia. The resultant nanoclusters are found to play an apparent role in improving the photocatalytic oxygen evolution of WO3 by promoting the surface separation of photoexcited charge-carriers. Electronic supplementary information (ESI) available: (1) Experimental section. (2) XRD patterns, FT-IR and Raman spectra of B2O3@WO3 and B2O3-xNx@WO3. (3) Time course of O2 evolution from water splitting using B2O3@WO3 and B2O3-xNx@WO3. (4) XRD pattern and SEM image of pure WO3, UV-visible absorption spectra of pure WO3 and N-WO3. (5) UV-visible absorption spectra of bulk B2O3 and schematic of band edges of WO3, bulk B2O3, and B2O3-xNx nanocluster. See DOI: 10.1039/c2nr11846g

Magnetically Driven Oscillator and Resonance: A Teaching Tool

ERIC Educational Resources Information Center

Erol, M.; Çolak, I. Ö.

2018-01-01

This paper reports a simple magnetically driven oscillator, designed and resolved in order to achieve a better student understanding and to overcome certain instructional difficulties. The apparatus is mainly comprised of an ordinary spring pendulum with a neodymium magnet attached to the bottom, a coil placed in the same vertical direction, an…

Optical communication in free space

NASA Technical Reports Server (NTRS)

Plotkin, H. H.; Mcavoy, N.; Fitzmaurice, M. W.

1974-01-01

Two classes of laser communication systems for handling very high data rates across inter-satellite distances are considered that provide for high antenna gains, wide modulation bandwidths, and optical receiver sensitivities. System design considerations are based upon the carbon dioxide laser modulation to accommodate digital or analog information, and the neodymium doped YAG laser pulse for digital modulation.

Precision operation of the Nova laser for fusion experiments

NASA Astrophysics Data System (ADS)

Caird, J. A.; Ehrlich, R. B.; Hermes, G. L.; Landen, O. L.; Laumann, C. W.; Lerche, R. A.; Miller, J. L.; Murray, J. E.; Nielsen, N. D.; Powell, H. T.; Rushford, M. C.; Saunders, R. L.; Thompson, C. E.; VanArsdall, P. J.; Vann, C. S.; Weiland, T. L.

1994-10-01

The operation of a Neodymium glass laser of a special design for fusion experiments is improved by a better pulse synchronization, the gain stabilization, and the laser diagnostics. We used sensor upgrading and antifriction coating of focusing lenses. The pointing accuracy of the Nova laser meets now our goal for precision operation. (AIP)

Amazing Vibrations within the Homopolar Motor

ERIC Educational Resources Information Center

Bednarek, Stanislaw

2018-01-01

The most common type of homopolar motor comprises a cylindrical neodymium magnet, a battery, and a non-ferromagnetic frame rotating around the battery. Here, the author substituted a coiled spring for the frame. Due to this change, a new and intriguing effect emerges, the axial buzzing of the spring during its rotation. This paper describes the…

Ames Lab 101: Rare-Earth Recycling

ScienceCinema

Ryan Ott

2017-12-22

Recycling keeps paper, plastics, and even jeans out of landfills. Could recycling rare-earth magnets do the same? Perhaps, if the recycling process can be improved. Scientists at the U.S. Department of Energy's Ames Laboratory are working to more effectively remove the neodymium, a rare earth, from the mix of other materials in a magnet.

Nd : glass rod laser with an output energy of 500 J

NASA Astrophysics Data System (ADS)

Shaykin, A. A.; Kuzmin, A. A.; Shaikin, I. A.; Burdonov, K. F.; Khazanov, E. A.

2016-04-01

The energy of two orthogonally polarised pulses injected into an available multistage amplifier based on neodymium phosphate glass rods was increased from 300 to 500 J (in both pulses). The second output pulse with an energy of 200 J will be used to pump an additional parametric amplifier of a petawatt laser.

Solar-pumped solid state Nd lasers

NASA Technical Reports Server (NTRS)

Williams, M. D.; Zapata, L.

1985-01-01

Solid state neodymium lasers are considered candidates for space-based polar-pumped laser for continuous power transmission. Laser performance for three different slab laser configurations has been computed to show the excellent power capability of such systems if heat problems can be solved. Ideas involving geometries and materials are offered as potential solutions to the heat problem.

High Temperature Evolution of PtNiAl-Based Thermal Barrier Coatings from First Principles Simulations

DTIC Science & Technology

2010-08-29

intergranular film, reminiscent of yttrium- aluminum - garnet , was presented. Such films tend to increase stability of the ceramic. Thus, as in the...and for grain boundaries doped with a series of early transition metals, as well as with barium, gadolinium , and neodymium. We predicted that the

Nd-doped Bi2O3 nanocomposites: simple synthesis and improved photocatalytic activity for hydrogen production under visible light

NASA Astrophysics Data System (ADS)

Al-Namshah, Khadijah S.; Mohamed, Reda M.

2018-04-01

Bi2O3 has 2.4 eV band gap energy, which means it absorb in visible region. Though the photocatalytic activity of Bi2O3 is extremely little due to rapid rate of photogenerated electron-hole recombination. To face the economical and practical needs, the photocatalytic efficiency of Bi2O3 should be upgraded. In this paper, this was achieved by addition of neodymium to Bi2O3 nanosheets and Nd/Bi2O3 nanocomposites were prepared by a easy process at room temperature using a surfactant of Pluronic F127. The Bi2O3 nanosheets and Nd/Bi2O3 nanocomposites were investigated by many tools. The photocatalytic activity of Nd/Bi2O3 samples is better than Bi2O3 due to reduced band gap and reduced electron-hole recombination of Bi2O3 with addition of neodymium. In addition, Nd/Bi2O3 nanocomposites exhibit photocatalytic stability for hydrogen production which enables it to be reused on other occasions also.

Laser shocking of 2024 and 7075 aluminum alloys

NASA Technical Reports Server (NTRS)

Clauer, A. H.; Fairand, B. P.; Slater, J. E.

1977-01-01

The effect of laser generated stress waves on the microstructure, hardness, strength and stress corrosion resistance of 2024 and 7075 aluminum alloys was investigated. Pulsed CO2 and neodymium-glass lasers were used to determine the effect of wavelength and pulse duration on pressure generation and material property changes. No changes in material properties were observed with CO2 laser. The strength and hardness of 2024-T351 and the strength of 7075-T73 aluminum alloys were substantially improved by the stress wave environments generated with the neodymium-glass laser. The mechanical properties of 2024-T851 and 7075-T651 were unchanged by the laser treatment. The correlation of the laser shock data with published results of flyer plate experiments demonstrated that a threshold pressure needed to be exceeded before strengthening and hardening could occur. Peak pressures generated by the pulsed laser source were less than 7.0 GPa which was below the threshold pressure required to change the mechanical properties of 2024-T851 and 7075-T651. Corrosion studies indicated that laser shocking increased the resistance to local attack in 2024-T351 and 7075-T651.

Kinetics and its accompanying thermodynamics studies on simultaneous complexation of heterobimetallic neodymium (III) with zinc (II) and L-tryptophan in aquated DMF using 4f-4f absorption spectra.

PubMed

Huidrom, Bimola; Singh, N Rajmuhon

2014-01-24

The 4f-4f absorption spectra of the simultaneous heterobimetallic complexation of trivalent neodymium ion with l-tryptophan and divalent zinc ion in aquated DMF (50%, v/v) at pH 6.0 was recorded at the time interval of 1h. From the observed absorption spectra, the values of intensity parameters such as oscillator strength (P) and Judd-Ofelt intensity (Tλ) parameters, kinetics and thermodynamics parameters were evaluated. The rate constant increases with an increase in the temperature along with the oscillator strengths and Judd-Ofelt intensity parameters. The positive values of the change in the standard enthalpy (ΔH°) and entropy (ΔS°) indicate that the complexation is endothermic. The negative values of the change in the standard free energy (ΔG°) in the range from 293.15 K to 308.15 K, indicate that the reaction occurs spontaneously and hence the formation of heterobimetallic complex in the solution is favored kinetically and thermodynamically. Copyright © 2013 Elsevier B.V. All rights reserved.

Kinetics and its accompanying thermodynamics studies on simultaneous complexation of heterobimetallic neodymium (III) with zinc (II) and L-tryptophan in aquated DMF using 4f-4f absorption spectra

NASA Astrophysics Data System (ADS)

Huidrom, Bimola; Rajmuhon Singh, N.

2014-01-01

The 4f-4f absorption spectra of the simultaneous heterobimetallic complexation of trivalent neodymium ion with L-tryptophan and divalent zinc ion in aquated DMF (50%, v/v) at pH 6.0 was recorded at the time interval of 1 h. From the observed absorption spectra, the values of intensity parameters such as oscillator strength (P) and Judd-Ofelt intensity (Tλ) parameters, kinetics and thermodynamics parameters were evaluated. The rate constant increases with an increase in the temperature along with the oscillator strengths and Judd-Ofelt intensity parameters. The positive values of the change in the standard enthalpy (ΔH°) and entropy (ΔS°) indicate that the complexation is endothermic. The negative values of the change in the standard free energy (ΔG°) in the range from 293.15 K to 308.15 K, indicate that the reaction occurs spontaneously and hence the formation of heterobimetallic complex in the solution is favored kinetically and thermodynamically.

Preparation and characterization of polystyrene/neodymium hydroxide (PS/Nd(OH)3) nano-composites

NASA Astrophysics Data System (ADS)

Alsewailem, Fares D.; Bagabas, Abdulaziz A.; Binkhodor, Yazeed A.

2018-03-01

Composites of polystyrene and Neodymium hydroxide nanrods (PS/Nd(OH)3) were formulated and characterized in this study. Cetyl (1-hexadccyl) trimethyl ammonium bromide (CTAB) was used as dispersion agent for the Nd(OH)3 rods in the PS matrix. PS/Nd(OH)3 composites were prepared by solution and melt compounding. Morphological, thermal, and mechanical properties of the prepared composites were investigated. CTAB was found to be more effective as dispersion agent in composites prepared by solution compounding in comparison with those prepared by melt compounding, and that was due to the mild conditions used in solution compounding. Nonetheless, impact strength of the composite at 0.5 wt% Nd(OH)3 was drastically reduced in the absence of CTAB. Both tensile and impact strengths were found to greatly decreased at higher loading of Nd(OH)3, e.g. 5 wt%, even with the use of CTAB. Thermal stability of the PS/Nd(OH)3 composites was noticeably increased at relatively low loading of Nd(OH)3, e.g. 0.5 wt%.

Economic Assessment for Recycling Critical Metals From Hard Disk Drives Using a Comprehensive Recovery Process

NASA Astrophysics Data System (ADS)

Nguyen, Ruby Thuy; Diaz, Luis A.; Imholte, D. Devin; Lister, Tedd E.

2017-09-01

Since the 2011 price spike of rare earth elements (REEs), research on permanent magnet recycling has blossomed globally in an attempt to reduce future REE criticality. Hard disk drives (HDDs) have emerged as one feasible feedstock for recovering valuable REEs such as praseodymium, neodymium, and dysprosium. Nevertheless, current processes for recycling electronic waste only focus on certain metals as a result of feedstock and metal price uncertainties. In addition, there is a perception that recycling REEs is unprofitable. To shed some light on the economic viability of REE recycling from U.S. HDDs, this article combines techno-economic information of an electro-hydrometallurgical process with end-of-life HDD availability in a simulation model. The results showed that adding REE recovery to an HDD base and precious metal recovery process was profitable given current prices. Recovered REEs from U.S. HDDs could meet up to 5.2% rest-of-world (excluding China) neodymium magnet demand. Feedstock, aluminum, and gold prices are key factors to recycling profitability. REEs contributed 13% to the co-recycling profit.

Thoracoscopic laser pneumoplasty in the treatment of diffuse bullous emphysema.

PubMed

Wakabayashi, A

1995-10-01

Thoracoscopic laser pneumoplasty in the treatment of diffuse bullous emphysema by means of a contact neodymium:yttrium-aluminum garnet laser was evaluated by a retrospective analysis of the first consecutive 500 procedures in 443 patients. The indication for thoracoscopic laser pneumoplasty was intractable dyspnea. Advanced age (mean age, 67 years), high oxygen dependency (70%), steroid use (46%), and markedly diminished physical capacity (2% bedridden and 27% wheelchair-bound) were noted. Thoracoscopic laser pneumoplasty was carried out under general anesthesia and one-lung ventilation. Type 3 bullae (381 procedures) were contracted by contact neodymium:yttrium-aluminum garnet laser and type 4 bullae (199 procedures) excised. The operative mortality rate was 4.8%. Subjective improvement was reported by 87% of the patients. Follow-up functional evaluation was available in 229 patients, which showed highly significant improvement. A comparison of preoperative and postoperative functional tests between type 3 and 4 bullae patients showed no significant difference, except the latter had higher decrease in airway resistance, residual volume, and total lung capacity. Thoracoscopic laser pneumoplasty is an effective treatment for both type 3 and 4 bullous emphysema with an acceptable risk.

Antimicrobial function of Nd3+-doped anatase titania-coated nickel ferrite composite nanoparticles: a biomaterial system.

PubMed

Rana, S; Rawat, J; Sorensson, M M; Misra, R D K

2006-07-01

The present study describes and makes a relative comparison of the antimicrobial function of undoped and neodymium-doped titania coated-nickel ferrite composite nanoparticles processed by uniquely combining the reverse micelle and chemical hydrolysis approaches. This methodology facilitates the formation of undoped and doped photocatalytic titania shells and a magnetic ferrite core. The ferrite core is needed to help in the removal of particles from the sprayed surface using a small magnetic field. Doping of the titania shell with neodymium significantly enhances the photocatalytic and anti-microbial function of the core-shell composite nanoparticles without influencing the magnetic characteristics of the nickel ferrite core. The increased performance is believed to be related to the inhibition of electron-hole recombination and a decrease in the band gap energy of titania. The retention of magnetic strength ensures controlled movement of the composite nanoparticles by the magnetic field, facilitating their application as removable anti-microbial photocatalyst nanoparticles. The consistent behavior of the composite nanoparticles points to the viability of the synthesis process adopted.

Scalable waveguide design for three-level operation in Neodymium doped fiber laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pax, Paul H.; Khitrov, Victor V.; Drachenberg, Derrek R.

We have constructed a double clad neodymium doped fiber laser operating on the three-level 4F 3/2 → 4I 9/2 transition. The laser has produced 11.5 W at 925 nm with 55% slope efficiency when pumped at 808 nm, comparable to the best previous results for a double-clad fiber configuration on this transition. Higher power pumping with both 808 nm and 880 nm sources resulted in an output of 27 W, albeit at lower slope efficiency. In both cases, output power was limited by available pump, indicating the potential for further power scaling. To suppress the stronger four-level 4F 3/2 →more » 4I 11/2 transition we developed a waveguide that provides spectral filtering distributed along the length of the fiber, based on an all-solid micro-structured optical fiber design, with resonant inclusions creating a leakage path to the cladding. Furthermore, the waveguide supports large mode areas and provides strong suppression at selectable wavelength bands, thus easing the restrictions on core and cladding sizes that limited power scaling of previous approaches.« less

Scalable waveguide design for three-level operation in Neodymium doped fiber laser

DOE PAGES

Pax, Paul H.; Khitrov, Victor V.; Drachenberg, Derrek R.; ...

2016-12-12

We have constructed a double clad neodymium doped fiber laser operating on the three-level 4F 3/2 → 4I 9/2 transition. The laser has produced 11.5 W at 925 nm with 55% slope efficiency when pumped at 808 nm, comparable to the best previous results for a double-clad fiber configuration on this transition. Higher power pumping with both 808 nm and 880 nm sources resulted in an output of 27 W, albeit at lower slope efficiency. In both cases, output power was limited by available pump, indicating the potential for further power scaling. To suppress the stronger four-level 4F 3/2 →more » 4I 11/2 transition we developed a waveguide that provides spectral filtering distributed along the length of the fiber, based on an all-solid micro-structured optical fiber design, with resonant inclusions creating a leakage path to the cladding. Furthermore, the waveguide supports large mode areas and provides strong suppression at selectable wavelength bands, thus easing the restrictions on core and cladding sizes that limited power scaling of previous approaches.« less

Programming jammed Codman Hakim programmable valves: study of an explanted valve and successful programming in a patient.

PubMed

Wong, Sui-To; Wen, Eleanor; Fong, Dawson

2013-08-01

Malfunction of a Codman Hakim programmable valve due to jamming of its programmable component may necessitate shunt revision. The authors report a method for programming jammed Codman Hakim programmable valves by using a Strata II magnet and additional neodymium magnets. The programming method was derived after studying a jammed valve in the laboratory that was explanted from an 10-year-old boy with a history of fourth ventricle ependymoma. Programming the explanted valve with a Codman programmer failed, but rotating a Strata II magnet above the valve resulted in rotation of the spiral cam in the valve. It was found that the Strata II magnet could be used to program the jammed valve by rotating the magnet 90° or multiples of 90° above the valve. The strength of the magnetic field of the Strata II magnet was able to be increased by putting neodymium magnets on it. The programming method was then successfully used in a patient with a jammed Codman Hakim programmable valve. After successful programming using this method, clinical and radiological follow-up of the patient was advised.

Treatment of café-au-lait macules with a high-fluenced 1064-nm Q-switched neodymium:yttrium aluminum garnet laser.

PubMed

Kim, Jiehoon; Hur, Hoon; Kim, Yu Ri; Cho, Sung Bin

2018-02-01

Café-au-lait macules (CALMs) are light to dark brown macules or patches of increased melanin concentration found along the dermoepidermal junction. Although many attempts to treat CALMs using various kinds of laser/light-based devices have been reported, CALMs remain refractory thereto with high recurrence rates. In this case series, we describe four patients with idiopathic CALMs that were effectively and safely treated with a non-ablative, high-fluenced, Q-switched (QS), 1064-nm neodymium:yttrium aluminum garnet (Nd:YAG) laser. The typical laser parameters for treating CALMs, including a spot size of 7-7.5 mm, a fluence of 2.4-2.5 J/cm 2 , and one to two passes until the appearance of mild erythema, but not petechiae, were utilized in this study over 12-24 treatment sessions at 2-week intervals. We suggest that high-fluenced QS 1064-nm Nd:YAG laser treatment can be used as an effective and alternative treatment modality for CALMs with minimal risk of side effects.

Photocatalytic Water Splitting for O2 Production under Visible Light Irradiation Using NdVO4-V2O5 Hybrid Powders

PubMed Central

Chiang, Tzu Hsuan; Chen, Tso-Ming

2017-01-01

The study investigated photocatalytic water splitting for O2 production under visible light irradiation using neodymium vanadium oxide (NdVO4) and vanadium oxide (V2O5) hybrid powders. The results in a sacrificial agent of 0.01 M AgNO3 solution were obtained, and the highest photocatalytic O2 evolution was 2.63 μmol/h, when the hybrid powders were prepared by mixing Nd and V at a volume ratio of 1:3 at a calcination temperature of 350 °C for 1 h. The hybrid powders were synthesized by neodymium nitrate and ammonium metavanadate using the glycothermal method in ethylene glycol at 120 °C for 1 h. The hybrid powders consisted of two shapes, NdVO4 nanoparticles and the cylindrical V2O5 particles, and they possessed the ability for photocatalytic oxygen (O2) evolution during irradiation with visible light. The band gaps and structures of the hybrid powders were analyzed using UV-visible spectroscopy and transmission electron microscopy. PMID:28772692

Femtosecond diode-pumped mode-locked neodymium lasers

NASA Astrophysics Data System (ADS)

Kubeček, Václav; Jelínek, Michal; Čech, Miroslav; Vyhlídal, David; Su, Liangbi; Jiang, Dapeng; Ma, Fengkai; Qian, Xiaobo; Wang, Jingya; Xu, Jun

2016-12-01

Fluoride-type crystals (CaF2, SrF2) doped with neodymium Nd3+ and codoped with buffer ions for breaking clusters of active ions and increasing fluorescence efficiency, present interesting alternative as laser active media for the diode-pumped mode-locked lasers. In comparison with widely used materials as Nd:YAG or Nd:YVO4, they have broad emission spectra as well as longer fluorescence lifetime, in comparison with Nd:glass, SrF2 and CaF2 have better thermal conductivity. In spite of the fact, that this thermal conductivity decreases with Nd3+ doping concentration, these crystals are alternative for the Nd:glass in subpicosecond mode-locked laser systems. In this paper we review the basic results reported recently on these active materials and in the second part we present our results achieved in low power diode pumped passively mode locked lasers with Nd,La:CaF2 and Nd,Y:SrF2 crystals. The pulses as short as 258 fs at wavelength of 1057 nm were obtained in the first case, while 5 ps long pulses at 1065 nm were generated from the second laser system.

Application of neodymium isotope ratio measurements for the origin assessment of uranium ore concentrates.

PubMed

Krajkó, Judit; Varga, Zsolt; Yalcintas, Ezgi; Wallenius, Maria; Mayer, Klaus

2014-11-01

A novel procedure has been developed for the measurement of (143)Nd/(144)Nd isotope ratio in various uranium-bearing materials, such as uranium ores and ore concentrates (UOC) in order to evaluate the usefulness and applicability of variations of (143)Nd/(144)Nd isotope ratio for provenance assessment in nuclear forensics. Neodymium was separated and pre-concentrated by extraction chromatography and then the isotope ratios were measured by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). The method was validated by the measurement of standard reference materials (La Jolla, JB-2 and BCR-2) and the applicability of the procedure was demonstrated by the analysis of uranium samples of world-wide origin. The investigated samples show distinct (143)Nd/(144)Nd ratio depending on the ore type, deposit age and Sm/Nd ratio. Together with other characteristics of the material in question, the Nd isotope ratio is a promising signature for nuclear forensics and suggests being indicative of the source material, the uranium ore. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Neodymium doped fluoroindogallate glasses as highly-sensitive luminescent non-contact thermometers

NASA Astrophysics Data System (ADS)

Nunes, Luiz A. O.; Souza, Adelmo S.; Carlos, Luís D.; Malta, Oscar L.

2017-01-01

Trivalent neodymium (Nd3+) can be used as high performance temperature luminescent ion sensor, namely in the near infrared spectral region. The disadvantage presented in the use of this ion is that transitions from thermally coupled levels show very different emission intensities. In order to solve this critical problem we propose to use Nd3+-doped fluoroindogallate glasses with low phonon cutoff energy (500 cm-1) as the active medium. By using a dopant concentration that minimizes losses due to cross relaxation processes and detecting the emissions of the thermally coupled levels with a R928 photomultiplier, without correction response for the wavelength dependence of the intensity, we have succeeded in getting the highest relative thermal sensitivities so far observed, 2.5%ṡK-1 and 7.4%ṡK-1, for the 4F5/2 → 4I9/2/4F3/2 → 4I9/2 and 4F7/2 → 4I9/2/4F3/2 → 4I9/2 intensity ratios, respectively at 288 K.

High-resolution separation of neodymium and dysprosium ions utilizing extractant-impregnated graft-type particles.

PubMed

Uchiyama, Shoichiro; Sasaki, Takaaki; Ishihara, Ryo; Fujiwara, Kunio; Sugo, Takanobu; Umeno, Daisuke; Saito, Kyoichi

2018-01-19

An efficient method for rare metal recovery from environmental water and urban mines is in high demand. Toward rapid and high-resolution rare metal ion separation, a novel bis(2-ethylhexyl) phosphate (HDEHP)-impregnated graft-type particle as a filler for a chromatography column is proposed. To achieve rapid and high-resolution separation, a convection-flow-aided elution mode is required. The combination of 35 μm non-porous particles and a polymer-brush-rich particle structure minimizes the distance from metal ion binding sites to the convection flow in the column, resulting in minimized diffusional mass transfer resistance and the convection-flow-aided elution mode. The HDEHP-impregnated graft-type non-porous-particle-packed cartridge developed in this study exhibited a higher separation performance for model rare metals, neodymium (III) and dysprosium (III) ions, and a narrower peak at a higher linear velocity, than those of previous HDEHP-impregnated fiber-packed and commercially available Lewatit ® VP OC 1026-packed cartridges. Copyright © 2017 Elsevier B.V. All rights reserved.

A new solid-state, frequency-doubled neodymium-YAG photocoagulation system.

PubMed

Jalkh, A E; Pflibsen, K; Pomerantzeff, O; Trempe, C L; Schepens, C L

1988-06-01

We have developed a solid-state laser system that produces a continuous green monochromatic laser beam of 532 nm by doubling the frequency of a neodymium-YAG laser wavelength of 1064 nm with a potassium-titamyl-phosphate crystal. Photocoagulation burns of equal size and intensity were placed in two rabbit eyes with the solid-state laser system and the regular green argon laser system, respectively, using the same slit-lamp mode of delivery. Histologic findings of lesion sections revealed no important differences between the two systems. In theory, the longer wavelength of the solid-state laser offers the advantages of less scattering in ocular media, higher absorption by oxyhemoglobin, and less absorption by macular xanthophyll than the 514-nm wavelength of the regular green argon laser. The solid-state laser has impressive technical advantages: it contains no argon-ion gas tube that wears out and is expensive to replace; it is much more power efficient, and thus considerably smaller and compact; it is sturdier and easily movable; it does not require external cooling; it uses a 220-V monophasic alternating current; and it requires little maintenance.

An experimental approach in revisiting the magnetic orientation of cattle

PubMed Central

Weijers, Debby; Hemerik, Lia; Heitkönig, Ignas M. A.

2018-01-01

In response to the increasing number of observational studies on an apparent south-north orientation in non-homing, non-migrating terrestrial mammals, we experimentally tested the alignment hypothesis using strong neodymium magnets on the resting orientation of individual cattle in Portugal. Contrary to the hypothesis, the 34 cows in the experiment showed no directional preference, neither with, nor without a strong neodymium magnet fixed to their collar. The concurrently performed 2,428 daytime observations—excluding the hottest part of the day—of 659 resting individual cattle did not show a south-north alignment when at rest either. The preferred compass orientation of these cows was on average 130 degrees from the magnetic north (i.e., south east). Cow compass orientation correlated significantly with sun direction, but not with wind direction. In as far as we can determine, this is the first experimental test on magnetic orientation in larger, non-homing, non-migrating mammals. These experimental and observational findings do not support previously published suggestions on the magnetic south-north alignment in these mammals. PMID:29641517

Processing development of 4 tantalum carbide-hafnium carbide and related carbides and borides for extreme environments

NASA Astrophysics Data System (ADS)

Gaballa, Osama Gaballa Bahig

Carbides, nitrides, and borides ceramics are of interest for many applications because of their high melting temperatures and good mechanical properties. Wear-resistant coatings are among the most important applications for these materials. Materials with high wear resistance and high melting temperatures have the potential to produce coatings that resist degradation when subjected to high temperatures and high contact stresses. Among the carbides, Al4SiC4 is a low density (3.03 g/cm3), high melting temperature (>2000°C) compound, characterized by superior oxidation resistance, and high compressive strength. These desirable properties motivated this investigation to (1) obtain high-density Al4SiC4 at lower sintering temperatures by hot pressing, and (2) to enhance its mechanical properties by adding WC and TiC to the Al4SiC4. Also among the carbides, tantalum carbide and hafnium carbide have outstanding hardness; high melting points (3880°C and 3890°C respectively); good resistance to chemical attack, thermal shock, and oxidation; and excellent electronic conductivity. Tantalum hafnium carbide (Ta4HfC 5) is a 4-to-1 ratio of TaC to HfC with an extremely high melting point of 4215 K (3942°C), which is the highest melting point of all currently known compounds. Due to the properties of these carbides, they are considered candidates for extremely high-temperature applications such as rocket nozzles and scramjet components, where the operating temperatures can exceed 3000°C. Sintering bulk components comprised of these carbides is difficult, since sintering typically occurs above 50% of the melting point. Thus, Ta4 HfC5 is difficult to sinter in conventional furnaces or hot presses; furnaces designed for very high temperatures are expensive to purchase and operate. Our research attempted to sinter Ta4HfC5 in a hot press at relatively low temperature by reducing powder particle size and optimizing the powder-handling atmosphere, milling conditions, sintering temperature, and hot-pressing pressure. Also, WC additions to Ta4HfC5 were found to improve densification and increase microhardness. The ability to process these materials at relatively low temperature would save energy and reduce cost. Boron-based hard materials are used in numerous applications such as industrial machining, armor plating, and wear-resistant coatings. It was often thought that in addition to strong bonding, super-hard materials must also possess simple crystallographic unit cells with high symmetry and a minimum number of crystal defects (e.g., diamond and cubic boron nitride (cBN)). However, one ternary boride, AlMgB14, deviates from this paradigm; AlMgB 14 has a large, orthorhombic unit cell (oI64) with multiple icosahedral boron units. TiB2 has been shown to be an effective reinforcing phase in AlMgB 14, raising hardness, wear resistance, and corrosion resistance. Thus, it was thought that adding other, similar phases (i.e., ZrB2 and HfB2) to AlMgB14 could lead to useful improvements in properties vis-à-vis pure AlMgB14. Group IV metal diborides (XB2, where X = Ti, Zr, or Hf) are hard, ultra-high temperature ceramics. These compounds have a primitive hexagonal crystal structure (hP3) with planes of graphite-like boride rings above and below planes of metal atoms. Unlike graphite, there is strong bonding between the planes, resulting in high hardness. For this study two-phase composites of 60 vol. % metal diborides with 40 vol. % AlMgB14 were produced and characterized.

Concentrations and isotopic compositions of neodymium in the eastern Indian Ocean and Indonesian straits

NASA Astrophysics Data System (ADS)

Jeandel, Catherine; Thouron, Danièle; Fieux, Michèle

1998-08-01

Four profiles of Nd concentration and isotopic composition were determined at two stations in the eastern Indian Ocean along a north/south section between Bali and Port-Hedland and at two others in the Timor and Sumba straits. Neodymium concentrations increase with depth, between 7.2 pmol/L at the surface to 41.7 pmol/L close to the bottom. The ɛ Nd of the different water masses along the section are -7.2 ± 0.2 for the Indian Bottom Waters and -6.1 ± 0.2 for the Indian Deep Waters. The intermediate and thermocline waters are less radiogenic at st-10 than at st-20 (-5.3 ± 0.3 and -3.6 ± 0.2, respectively). In the Timor Passage and Sumba Strait, ɛ Nd of the Indonesian waters is -4.1 ± 0.2 and that of the North Indian Intermediate Waters is -2.6 ± 0.3. These distinct isotopic signals constrain the origins of the different water masses sampled in the eastern Indian Ocean. They fix the limit of the nonradiogenic Antarctic and Indian contributions to the southern part of the section whereas the northern part is influenced by radiogenic Indonesian flows. In addition, the neodymium isotopic composition suggests that in the north, deep waters are influenced by a radiogenic component originating from the Sunda Arch Slope flowing deeper than 1200 m, which was not documented previously. Mixing calculations assess the conservativity of ɛ Nd on the scale of an oceanic basin. The origin of the surprising radiogenic signal of the NIIW is discussed and could result from a remobilization of Nd sediment-hosted on the Java shelf, requiring important dissolved/particulate exchange processes. Such processes, occurring in specific areas, could play an important role in the world ocean Nd budget.

Bioavailable concentrations of germanium and rare earth elements in soil as affected by low molecular weight organic acids and root exudates

NASA Astrophysics Data System (ADS)

Wiche, Oliver; Székely, Balázs; Kummer, Nicolai-Alexeji; Heinemann, Ute; Tesch, Silke; Heilmeier, Hermann

2014-05-01

Availability of elements in soil to plant is generally dependent on the solubility and mobility of elements in soil solution which is controlled by soil, elemental properties and plant-soil interactions. Low molecular organic acids or other root exudates may increase mobility and availability of certain elements for plants as an effect of lowering pH in the rhizosphere and complexation. However, these processes take place in a larger volume in soil, therefore to understand their nature, it is also important to know in which layers of the soil what factors modify these processes. In this work the influence of citric acid and root exudates of white lupin (Lupinus albus L.) on bioavailable concentrations of germanium, lanthan, neodymium, gadolinium and erbium in soil solution and uptake in root and shoot of rape (Brassica napus L.), comfrey (Symphytum officinale L.), common millet (Panicum milliaceum L.) and oat (Avena sativa L.) was investigated. Two different pot experiments were conducted: (1) the mentioned plant species were treated with nutrient solutions containing various amount of citric acid; (2) white lupin was cultivated in mixed culture (0 % lupin, 33 % lupin) with oat (Avena sativa L.) and soil solution was obtained by plastic suction cups placed at various depths. As a result, addition of citric acid significantly increased germanium concentrations in plant tissue of comfrey and rape and increased translocation of germanium, lanthan, neodymium, gadolinium and erbium from root to shoot. The cultivation of white lupin in mixed culture with oat led to significantly higher concentrations of germanium and increasing concentrations of lanthan, neodymium, gadolinium and erbium in soil solution and aboveground plant tissue. In these pots concentrations of citric acid in soil solution were significantly higher than in the control. The results show, that low molecular organic acids exuded by plant roots are of great importance for the mobilization of germanium, lanthan, neodymium, gadolinium and erbium in the rhizosphere and therefore the enhancement of bioavailability of the mentioned elements to plants. Based on the suction cup experiment we conclude that in vertical soil profile the bioavailable germanium is heavily affected by the activity of exudates, as the complexation processes of germanium take place at the root zone and below affected by the interplay of the infiltration of citric acid solutions and the actually produced exudates. These studies have been carried out in the framework of the PhytoGerm project, financed by the Federal Ministry of Education and Research, Germany. BS contributed as an Alexander von Humboldt Research Fellow. The authors are grateful to students and laboratory assistants contributing in the field work and sample preparation.

Evaluating United States and world consumption of neodymium, dysprosium, terbium, and praseodymium in final products

NASA Astrophysics Data System (ADS)

Hart, Matthew

This paper develops scenarios of future rare-earth-magnet metal (neodymium, dysprosium, terbium, and praseodymium) consumption in the permanent magnets used in wind turbines and hybrid electric vehicles. The scenarios start with naive base-case scenarios for growth in wind-turbine and hybrid-electric-vehicle sales over the period 2011 to 2020, using historical data for each good. These naive scenarios assume that future growth follows time trends in historical data and does not depend on any exogenous variable. Specifically, growth of each technological market follows historical time trends, and the amount of rare earths used per unit of technology remains fixed. The chosen reference year is 2010. Implied consumptions of the rare earth magnet metals are calculated from these scenarios. Assumptions are made for the material composition of permanent magnets, the market share of permanent-magnet wind turbines and vehicles, and magnet weight per unit of technology. Different scenarios estimate how changes in factors like the material composition of magnets, growth of the economy, and the price of a substitute could affect future consumption. Each scenario presents a different method for reducing rare earth consumption and could be interpreted as potential policy choices. In 2010, the consumption (metric tons, rare-earth-oxide equivalent) of each rare-earth-magnet metal was as follows. Total neodymium consumption in the world for both technologies was 995 tons; dysprosium consumption was 133 tons; terbium consumption was 50 tons; praseodymium consumption was zero tons. The base scenario for wind turbines shows there could be strong, exponential growth in the global wind turbine market. New U.S. sales of hybrid vehicles would decline (in line with the current economic recession) while non-U.S. sales increase through 2020. There would be an overall increase in the total amount of magnetic rare earths consumed in the world. Total consumption of each rare earth in the short-term (2015) and mid-term (2020) scenarios could be between: 1,984 to 6,475 tons (2015) and 3,487 to 13,763 tons (2020) of neodymium; 331 to 864 tons (2015) and 587 to 1,834 tons (2020) of dysprosium; 123 to 325 tons (2015) and 219 to 687 tons (2020) of terbium; finally, zero to 871 tons (2015) and zero to 1,493 tons (2020) of praseodymium. Hybrid vehicle sales in non-U.S. countries could account for a large portion of magnetic rare earth consumption. Wind turbine and related rare earth consumption growth will also be driven by non-U.S. countries, especially developing nations like China. Despite wind turbines using bigger magnets, the sheer volume of hybrids sold and non-U.S. consumers could account for most future consumption of permanent magnets and their rare earths.

How to estimate hardness of crystals on a pocket calculator

NASA Astrophysics Data System (ADS)

Šimůnek, Antonín

2007-05-01

A generalization of the semiempirical microscopic model of hardness is presented and applied to currently studied borides, carbides, and nitrides of heavy transition metals. The hardness of OsB, OsC, OsN, PtN, RuC, RuB2 , ReB2 , OsB2 , IrN2 , PtN2 , and OsN2 crystals in various structural phases is predicted. It is found that none of the transition metal crystals is superhard, i.e., with hardness greater than 40GPa . The presented method provides materials researchers with a practical tool in the search for new hard materials.

First-principles modeling of hardness in transition-metal diborides

NASA Astrophysics Data System (ADS)

Lazar, Petr; Chen, Xing-Qiu; Podloucky, Raimund

2009-07-01

Based on recent experiments, the diborides OsB2 and ReB2 were proposed to be ultraincompressible and superhard materials. By application of an ab initio density-functional theory approach we investigate the elastic and cleavage fracture properties of the borides MB2 ( M=Hf , Ta, W, Re, Os, and Ir). We derive a direct correlation between the lowest calculated critical cleavage stress and the experimental (micro)hardness. By calculating the critical shear stress and estimating the possibility of dislocation emission we can justify the prediction that ReB2 is indeed a superhard material.

Reactive multilayer synthesis of hard ceramic foils and films

DOEpatents

Makowiecki, D.M.; Holt, J.B.

1996-02-13

A method is disclosed for synthesizing hard ceramic materials such as carbides, borides and aluminides, particularly in the form of coatings provided on another material so as to improve the wear and abrasion performance of machine tools, for example. The method involves the sputter deposition of alternating layers of reactive metals with layers of carbon, boron, or aluminum and the subsequent reaction of the multilayered structure to produce a dense crystalline ceramic. The material can be coated on a substrate or formed as a foil which can be coiled as a tape for later use.

Thermodynamic analysis of chemical compatibility of several compounds with Fe-Cr-Al alloys

NASA Technical Reports Server (NTRS)

Misra, Ajay K.

1993-01-01

Chemical compatibility between Fe-19.8Cr-4.8Al (weight percent), which is the base composition for the commercial superalloy MA956, and several carbides, borides, nitrides, oxides, and silicides was analyzed from thermodynamic considerations. The effect of addition of minor alloying elements, such as Ti, Y, and Y2O3, to the Fe-Cr-Al alloy on chemical compatibility between the alloy and various compounds was also analyzed. Several chemically compatible compounds that can be potential reinforcement materials and/or interface coating materials for Fe-Cr-Al based composites were identified.

Lightweight porous plastic plaque. [nickel cadmium batteries

NASA Technical Reports Server (NTRS)

Reid, M.

1978-01-01

The porosity and platability of various materials were investigated to determine a suitable substrate for nickel-plated electrodes. Immersion, ultrasonics, and flow-through plating techniques were tried using nonproprietary formulations, and proprietary phosphide and boride baths. Modifications to the selected material include variations in formulation and treatment, carbon loading to increase conductivity, and the incorporation of a grid. Problems to be solved relate to determining conductivities and porosities as a function of amount of nickel plated on the plastics; loading; charge and discharge curves of electrodes at different current densities; cell performance; and long-term degradation of electrodes.

In-situ Formation of Reinforcement Phases in Ultra High Temperature Ceramic Composites

NASA Technical Reports Server (NTRS)

Stackpoole, Margaret M (Inventor); Gasch, Matthew J (Inventor); Olson, Michael W (Inventor); Hamby, Ian W. (Inventor); Johnson, Sylvia M (Inventor)

2013-01-01

A tough ultra-high temperature ceramic (UHTC) composite comprises grains of UHTC matrix material, such as HfB.sub.2, ZrB.sub.2 or other metal boride, carbide, nitride, etc., surrounded by a uniform distribution of acicular high aspect ratio reinforcement ceramic rods or whiskers, such as of SiC, is formed from uniformly mixing a powder of the UHTC material and a pre-ceramic polymer selected to form the desired reinforcement species, then thermally consolidating the mixture by hot pressing. The acicular reinforcement rods may make up from 5 to 30 vol % of the resulting microstructure.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mbarki, Mohammed; Touzani, Rachid St.; Rehorn, Christian W.G.

The new ternary transition metal-rich borides Ta{sub 2}OsB{sub 2} and TaRuB have been successfully synthesized by arc-melting the elements in a water-cooled crucible under an argon atmosphere. The crystal structures of both compounds were solved by single-crystal X-ray diffraction and their metal compositions were confirmed by EDX analysis. It was found that Ta{sub 2}OsB{sub 2} and TaRuB crystallize in the tetragonal Nb{sub 2}OsB{sub 2} (space group P4/mnc, no. 128) and the orthorhombic NbRuB (space group Pmma, no. 51) structure types with lattice parameters a=5.878(2) Å, c=6.857(2) Å and a=10.806(2) Å, b=3.196(1) Å, c=6.312(2) Å, respectively. Furthermore, crystallographic, electronic and bondingmore » characteristics have been studied by density functional theory (DFT). Electronic structure relaxation has confirmed the crystallographic parameters while COHP bonding analysis indicates that B{sub 2}-dummbells are the strongest bonds in both compounds. Moreover, the formation of osmium dumbbells in Ta{sub 2}OsB{sub 2} through a Peierls distortion along the c-axis, is found to be the origin of superstructure formation. Magnetic susceptibility measurements reveal that the two phases are Pauli paramagnets, thus confirming the theoretical DOS prediction of metallic character. Also hints of superconductivity are found in the two phases, however lack of single phase samples has prevented confirmation. Furthermore, the thermodynamic stability of the two modifications of AMB (A=Nb, Ta; M =Ru, Os) are studied using DFT, as new possible phases containing either B{sub 4}- or B{sub 2}-units are predicted, the former being the most thermodynamically stable modification. - Graphical abstract: The two new ternary tantalum borides, Ta{sub 2}OsB{sub 2} and TaRuB, have been discovered. Their crystal structures contain boron dumbbells, which are the strongest bonds. Peirls distortion is found responsible for Os{sub 2}-dumbbells formation in Ta{sub 2}OsB{sub 2}. Ta{sub 2}OsB{sub 2} and TaRuB are Pauli paramagnet and potential superconductors. - Highlights: • Two new ternary tantalum borides, Ta{sub 2}OsB{sub 2} and TaRuB, discovered. • Boron dumbbells are the strongest bonds in Ta{sub 2}OsB{sub 2} and TaRuB. • Peierls distortion responsible for Os{sub 2}-dumbbells formation in Ta{sub 2}OsB{sub 2.} • Ta{sub 2}OsB{sub 2} and TaRuB are Pauli paramagnet. • Ta{sub 2}OsB{sub 2} and TaRuB contain pseudogaps and are potential superconductors.« less

The Shaking Torch: Another Variation on the Inductive Force

ERIC Educational Resources Information Center

Thompson, Frank

2010-01-01

A recent article showed how the influx of neodymium magnets has provided striking demonstrations of the interactions between magnets and conductors. The "shaking torch" is yet another example. Many of these torches require no batteries and can be submerged in water--indeed, a light for life. In this article, the author disassembles a shaking torch…

Electromagnetic Induction with Neodymium Magnets

ERIC Educational Resources Information Center

Wood, Deborah; Sebranek, John

2013-01-01

In April 1820, Hans Christian Ørsted noticed that the needle of a nearby compass deflected briefly from magnetic north each time the electric current of the battery he was using for an unrelated experiment was turned on or off. Upon further investigation, he showed that an electric current flowing through a wire produces a magnetic field. In 1831…

Rare Earths; The Fraternal Fifteen (Rev.)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gschneidner, Jr., Karl A.

1966-01-01

Rare earths are a set of 15 elements: lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium. They are not rare and not earths; they are metals and quite abundant. They are studied to develop commercial products which are beneficial to mankind, and because some rare earths are important to fission products.

Demonstration of Clean Particle Seeding for Particle Image Velocimetry in a Closed Circuit Supersonic Wind Tunnel

DTIC Science & Technology

2007-03-01

plane in space. Many such lasers are used for PIV, including: Copper vapor, Argon ion, Helium-Neon, Yttrium Aluminum Garnet (YAG) and Neodymium doped ...velocimetry to measure the velocities of nanoparticles in nanofluids .” Optics Express. Vol 14, No 17: 7559-7566 (2006) 15. Poggie, J., Erbland, P.J., Smits

Low-Cost Magnetic Stirrer from Recycled Computer Parts with Optional Hot Plate

ERIC Educational Resources Information Center

Guidote, Armando M., Jr.; Pacot, Giselle Mae M.; Cabacungan, Paul M.

2015-01-01

Magnetic stirrers and hot plates are key components of science laboratories. However, these are not readily available in many developing countries due to their high cost. This article describes the design of a low-cost magnetic stirrer with hot plate from recycled materials. Some of the materials used are neodymium magnets and CPU fans from…

Cutaneous applications of lasers.

PubMed

Ries, W R; Speyer, M T

1996-12-01

The cutaneous application of lasers today includes more selective and less damaging devices. Carbon dioxide, neodymium:yttrium-aluminum-garnet, potassium titanyl phosphate, argon, and yellow lasers are most prevalent in treating cutaneous lesions. Specific techniques in skin resurfacing, keloid excision, rhinophyma, actinic cheilitis ablation, and excision of superficial cutaneous tumors are discussed. Proper management of cutaneous vascular lesions is also presented.

Flexible Interior-Impression-Molding Tray

NASA Technical Reports Server (NTRS)

Anders, Jeffrey E.

1991-01-01

Device used inside combustion chamber of complicated shape for nondestructive evaluation of qualities of welds, including such features as offset, warping, misalignment of parts, and dropthrough. Includes flexible polypropylene tray trimmed to fit desired interior surface contour. Two neodymium boron magnets and inflatable bladder attached to tray. Tray and putty inserted in cavity to make mold of interior surface.

New ternary tantalum borides containing boron dumbbells: Experimental and theoretical studies of Ta2OsB2 and TaRuB

NASA Astrophysics Data System (ADS)

Mbarki, Mohammed; Touzani, Rachid St.; Rehorn, Christian W. G.; Gladisch, Fabian C.; Fokwa, Boniface P. T.

2016-10-01

The new ternary transition metal-rich borides Ta2OsB2 and TaRuB have been successfully synthesized by arc-melting the elements in a water-cooled crucible under an argon atmosphere. The crystal structures of both compounds were solved by single-crystal X-ray diffraction and their metal compositions were confirmed by EDX analysis. It was found that Ta2OsB2 and TaRuB crystallize in the tetragonal Nb2OsB2 (space group P4/mnc, no. 128) and the orthorhombic NbRuB (space group Pmma, no. 51) structure types with lattice parameters a=5.878(2) Å, c=6.857(2) Å and a=10.806(2) Å, b=3.196(1) Å, c=6.312(2) Å, respectively. Furthermore, crystallographic, electronic and bonding characteristics have been studied by density functional theory (DFT). Electronic structure relaxation has confirmed the crystallographic parameters while COHP bonding analysis indicates that B2-dummbells are the strongest bonds in both compounds. Moreover, the formation of osmium dumbbells in Ta2OsB2 through a Peierls distortion along the c-axis, is found to be the origin of superstructure formation. Magnetic susceptibility measurements reveal that the two phases are Pauli paramagnets, thus confirming the theoretical DOS prediction of metallic character. Also hints of superconductivity are found in the two phases, however lack of single phase samples has prevented confirmation. Furthermore, the thermodynamic stability of the two modifications of AMB (A=Nb, Ta; M =Ru, Os) are studied using DFT, as new possible phases containing either B4- or B2-units are predicted, the former being the most thermodynamically stable modification.

Design for low-cost gas metal arc weld-based aluminum 3-D printing

NASA Astrophysics Data System (ADS)

Haselhuhn, Amberlee S.

Additive manufacturing, commonly known as 3-D printing, has the potential to change the state of manufacturing across the globe. Parts are made, or printed, layer by layer using only the materials required to form the part, resulting in much less waste than traditional manufacturing methods. Additive manufacturing has been implemented in a wide variety of industries including aerospace, medical, consumer products, and fashion, using metals, ceramics, polymers, composites, and even organic tissues. However, traditional 3-D printing technologies, particularly those used to print metals, can be prohibitively expensive for small enterprises and the average consumer. A low-cost open-source metal 3-D printer has been developed based upon gas metal arc weld (GMAW) technology. Using this technology, substrate release mechanisms have been developed, allowing the user to remove a printed metal part from a metal substrate by hand. The mechanical and microstructural properties of commercially available weld alloys were characterized and used to guide alloy development in 4000 series aluminum-silicon alloys. Wedge casting experiments were performed to screen magnesium, strontium, and titanium boride alloying additions in hypoeutectic aluminum-silicon alloys for their properties and the ease with which they could be printed. Finally, the top performing alloys, which were approximately 11.6% Si modified with strontium and titanium boride were cast, extruded, and drawn into wire. These wires were printed and the mechanical and microstructural properties were compared with those of commercially available alloys. This work resulted in an easier-to-print aluminum-silicon-strontium alloy that exhibited lower porosity, equivalent yield and tensile strengths, yet nearly twice the ductility compared to commercial alloys.

The complex metal-rich boride Ti1+xRh2-x+yIr3-yB3 (x=0.68, y=1.06) with a new structure type containing B4 zigzag fragments: Synthesis, crystal chemistry and theoretical calculations

NASA Astrophysics Data System (ADS)

Goerens, Christian; Fokwa, Boniface P. T.

2012-08-01

Polycrystalline samples and single crystals of the new complex boride Ti1+xRh2-x+yIr3-yB3 (x=0.68; y=1.06) were synthesized by arc-melting the elements in a water-cooled copper crucible under an argon atmosphere and characterized by X-Ray diffraction as well as EDX measurements. The crystal structure was refined on the basis of single crystal data. The new phase, which represents a new structure type containing trans zigzag B4 fragments as well as isolated boron atoms crystallizes in the orthorhombic space group Pbam (Nr. 55) with the lattice parameters a=8.620(1) Å, b=14.995(2) Å and c=3.234(1) Å. First-principles density functional theory calculations using the Vienna ab-initio simulation package (VASP) were performed on an appropriate structural model (using a supercell approach) and the experimental crystallographic data could be reproduced accurately. Based on this model, the density of states and crystal orbital Hamilton population (for bonding analysis) were calculated, using the linear muffin-tin orbital atomic sphere approximation (LMTO-ASA) method. According to these calculations, this metal-rich compound should be metallic, as expected. Furthermore, very strong boron-boron interactions are observed in the trans zigzag B4 fragment, which induce a clear differentiation of two types of metal-boron contacts with different strength. The observed three-dimensional metal-metal interaction is in good agreement with the predicted metallic behavior.

Three-dimensional nanometer scale analyses of precipitate structures and local compositions in titanium aluminide engineering alloys

NASA Astrophysics Data System (ADS)

Gerstl, Stephan S. A.

Titanium aluminide (TiAl) alloys are among the fastest developing class of materials for use in high temperature structural applications. Their low density and high strength make them excellent candidates for both engine and airframe applications. Creep properties of TiAl alloys, however, have been a limiting factor in applying the material to a larger commercial market. In this research, nanometer scale compositional and structural analyses of several TiAl alloys, ranging from model Ti-Al-C ternary alloys to putative commercial alloys with 10 components are investigated utilizing three dimensional atom probe (3DAP) and transmission electron microscopies. Nanometer sized borides, silicides, and carbide precipitates are involved in strengthening TiAl alloys, however, chemical partitioning measurements reveal oxygen concentrations up to 14 at. % within the precipitate phases, resulting in the realization of oxycarbide formation contributing to the precipitation strengthening of TiAl alloys. The local compositions of lamellar microstructures and a variety of precipitates in the TiAl system, including boride, silicide, binary carbides, and intermetallic carbides are investigated. Chemical partitioning of the microalloying elements between the alpha2/gamma lamellar phases, and the precipitate/gamma-matrix phases are determined. Both W and Hf have been shown to exhibit a near interfacial excess of 0.26 and 0.35 atoms nm-2 respectively within ca. 7 nm of lamellar interfaces in a complex TiAl alloy. In the case of needle-shaped perovskite Ti3AlC carbide precipitates, periodic domain boundaries are observed 5.3+/-0.8 nm apart along their growth axis parallel to the TiAl[001] crystallographic direction with concomitant composition variations after 24 hrs. at 800°C.

Metallic glass composition

DOEpatents

Kroeger, Donald M.; Koch, Carl C.

1986-01-01

A metallic glass alloy that is either iron-based or nickel-based or based on a mixture of iron and nickel, containing lesser amounts of elements selected from the group boron, silicon carbon and phosphorous to which is added an amount of a ductility enhancing element selected from the group cerium, lanthanum, praseodymium and neodymium sufficient to increase ductility of the metallic glass upon annealing.

High average power laser using a transverse flowing liquid host

DOEpatents

Ault, Earl R.; Comaskey, Brian J.; Kuklo, Thomas C.

2003-07-29

A laser includes an optical cavity. A diode laser pumping device is located within the optical cavity. An aprotic lasing liquid containing neodymium rare earth ions fills the optical cavity. A circulation system that provides a closed loop for circulating the aprotic lasing liquid into and out of the optical cavity includes a pump and a heat exchanger.

Magnetogate: Using an iPhone Magnetometer for Measuring Kinematic Variables

ERIC Educational Resources Information Center

Temiz, Burak Kagan; Yavuz, Ahmet

2016-01-01

This paper presents a method to measure the movement of an object from specific locations on a straight line using an iPhone's magnetometer. In this method, called "magnetogate," an iPhone is placed on a moving object (in this case a toy car) and small neodymium magnets are arranged at equal intervals on one side of a straight line. The…

Environmental Acceptable Medium Caliber Ammunition Percussion Primers

DTIC Science & Technology

2008-05-01

the nanoparticles extremely hydrophobic. The alternative treatment of the solution was the addition of ammonium dihydrogen phosphate (ADP) to serve as...Ultrafine Aluminum Nanoparticles," LA-UR-04-2921. 49 ACRONYM LIST ADP Ammonium Dihydrogen Phosphate Al Aluminum ARDEC Armament Research Development and...Nitrocellulose Nd:Yag Neodymium -doped yttrium aluminum garnet NSWC-IH Naval Surface Warfare Center- Indian Head PAD Propellant actuated device PETN

Laser applications in the tracheobronchial tree.

PubMed

Rebeiz, E E; Shapsay, S M; Ingrams, D R

1996-12-01

This article outlines the historical development of the use of lasers in the tracheobronchial tree, the current indications for the use of carbon dioxide and neodymium:yttrium-aluminum-garnet lasers, and the management of complications. The merits of other laser wavelengths are mentioned, including use of the potassium titanyl phosphate laser in the pediatric airway. Photodynamic therapy is discussed, and some future developments are introduced.

An Integrated Rare Earth Elements Supply Chain Strategy

DTIC Science & Technology

2011-02-24

iron boron magnets in Joint Direct Attack Munitions (JDAM) smart bombs; neodymium-yttrium- aluminum - garnet lasers and range finders in multiple weapon...components Europium 63 computer screens, fluorescent lights Gadolinium 64 magnetic applications, phosphors Terbium 65 phosphors, projection TV’s...Defense Stockpile report advised several production delays of weapons systems were caused by lanthanum, cerium, europium and gadolinium supply

Effect of anterior capsule contraction on visual function after cataract surgery.

PubMed

Hayashi, Ken; Hayashi, Hideyuki

2007-11-01

To examine the effect of contraction of the anterior capsule opening after cataract surgery on visual acuity and contrast sensitivity. Hayashi Eye Hospital, Fukuoka, Japan. Thirty-two eyes of 32 consecutive patients who showed marked contraction of the anterior capsule opening after implantation of an intraocular lens were recruited. The area of the anterior capsule opening was measured by Scheimpflug videophotography before and after neodymium:YAG (Nd:YAG) laser anterior capsulotomy and was correlated with visual acuity and contrast sensitivity. After Nd:YAG laser anterior capsulotomy, the mean area of the anterior capsule opening increased significantly from 8.2 mm(2) to 18.0 mm(2) (P<.0001). Contrast sensitivity at most visual angles also improved significantly after Nd:YAG anterior capsulotomy, although visual acuity did not. The area of the anterior capsule opening before anterior capsulotomy was correlated significantly with contrast sensitivity but not with visual acuity, whereas there was no correlation between the opening area after anterior capsulotomy and visual acuity or contrast sensitivity. Contraction of the anterior capsule opening after cataract surgery significantly diminished contrast sensitivity in proportion to the opening area but did not markedly worsen visual acuity. Neodymium:YAG laser anterior capsulotomy improved contrast sensitivity.

Neodymium(III) Complexes of Dialkylphosphoric and Dialkylphosphonic Acids Relevant to Liquid-Liquid Extraction Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lumetta, Gregg J.; Sinkov, Sergey I.; Krause, Jeanette A.

2016-01-27

The complexes formed during the extraction of neodymium(III) into hydrophobic solvents containing acidic organophosphorus extractants were probed by single-crystal X-ray diffractometry, visible spectrophotometry, and Fourier-transform infrared spectroscopy. The crystal structure of the compound Nd(DMP)3 (1, DMP = dimethyl phosphate) revealed a polymeric arrangement in which each Nd(III) center is surrounded by six DMP oxygen atoms in a pseudo-octahedral environment. Adjacent Nd(III) ions are bridged by (MeO)2POO– anions, forming the polymeric network. The diffuse reflectance visible spectrum of 1 is nearly identical to that of the solid that is formed when an n-dodecane solution of di-(2-ethylhexyl)phosphoric acid (HA) is saturated withmore » Nd(III), indicating a similar coordination environment around the Nd center in the NdA3 solid. The visible spectrum of the HA solution fully loaded with Nd(III) is very similar to that of the NdA3 material, both displaying hypersensitive bands characteristic of an pseudo-octahedral coordination environment around Nd. These spectral characteristics persisted across a wide range of organic Nd concentrations, suggesting that the pseudo-octahedral coordination environment is maintained from dilute to saturated conditions.« less

A supported liquid membrane system for the selective recovery of rare earth elements from neodymium-based permanent magnets

DOE PAGES

Kim, Daejin; Powell, Lawrence; Delmau, Lætitia H.; ...

2016-04-04

We present that the rare earth elements (REEs) play a vital role in the development of green energy and high-tech industries. In order to meet the fast-growing demand and to ensure sufficient supply of the REEs, it is essential to develop an efficient REE recovery process from post-consumer REE-containing products. In this research effort, we have developed a supported liquid membrane system utilizing polymeric hollow fiber modules to extract REEs from neodymium-based magnets with neutral extractants such as tetraoctyl digylcol amide (TODGA). The effect of process variables such as REE concentration, molar concentration of acid, and membrane area on REEmore » recovery was investigated. We have demonstrated the selective extraction and recovery of REEs such as Nd, Pr, and Dy without co-extraction of non-REEs from permanent NdFeB magnets through the supported liquid membrane system. The extracted REEs were then recovered by precipitation followed by the annealing step to obtain crystalline REE powders in nearly pure form. Finally, the recovered REE oxides were characterized by X-ray diffraction, scanning electron microscope coupled with energy-dispersive X-ray spectroscopy, and inductively coupled plasma–optical emission spectroscopy.« less

Stability optimization of microbial surface-enhanced Raman spectroscopy detection with immunomagnetic separation beads

NASA Astrophysics Data System (ADS)

Uusitalo, Sanna; Kögler, Martin; Välimaa, Anna-Liisa; Petäjä, Jarno; Kontturi, Ville; Siitonen, Samuli; Laitinen, Riitta; Kinnunen, Matti; Viitala, Tapani; Hiltunen, Jussi

2017-03-01

Immunomagnetic separation (IMS) beads with antibody coating are an interesting option for biosensing applications for the identification of biomolecules and biological cells, such as bacteria. The paramagnetic properties of the beads can be utilized with optical sensing by migrating and accumulating the beads and the bound analytes toward the focus depth of the detection system by an external magnetic field. The stability of microbial detection with IMS beads was studied by combining a flexible, inexpensive, and mass producible surface-enhanced Raman spectroscopy (SERS) platform with gold nanoparticle detection and antibody recognition by the IMS beads. Listeria innocua ATCC 33090 was used as a model sample and the effect of the IMS beads on the detected Raman signal was studied. The IMS beads were deposited into a hydrophobic sample well and accumulated toward the detection plane by a neodymium magnet. For the first time, it was shown that the spatial stability of the detection could be improved up to 35% by using IMS bead capture and sample well placing. The effect of a neodymium magnet under the SERS chip improved the temporal detection and significantly reduced the necessary time for sample stabilization for advanced laboratory testing.

Effect of Nd Doping on Dielectric and Impedance Properties of PZT Nanoceramics

NASA Astrophysics Data System (ADS)

Kour, P.; Pradhan, S. K.; Kumar, Pawan; Sinha, S. K.; Kar, Manoranjan

2018-02-01

Neodymium-doped lead zirconate tianate, i.e. Pb1-x Nd x Zr0.52Ti0.48O3 (PNZT) ceramics, with x = 0-10 mol.% has been prepared by the sol-gel process. X-ray diffraction pattern at room temperature shows the pyrochlore free phase for all samples. The structural analysis suggests the coexistence of both rhombohedral (R3m space group) and tetragonal (P4 mm space group) crystal symmetries. Scanning electron micrographs of the samples show uniform distribution of grain and grain boundaries. Dielectric constant increases with the increase in neodymium concentration in the crystal lattice. Degree of diffuse phase transition increases with the increase in Nd3+ concentration in the sample. Nd3+ incorporation into the lead zirconatetitanate (PZT) lattice enhances the spreading factor. Interaction between neighbouring dipoles decreases with the increase of Nd3+ in PZT lattice. The conduction mechanism of the sample can be attributed to the overlapping large polar tunnelling. Second-order dielectric phase transition has been observed at the Curie temperature. The electrical properties of the sample can be explained by considering grain and grain boundaries contributions. All the samples show the poly-dispersive non-Debye type relaxation.

Long-Pulsed 532-Nm Neodymium-Doped Yttrium Aluminium Garnet Laser for Treatment of Facial Plane Warts in 160 Yemeni Patients.

PubMed

Alshami, Mohammad Ali; Mohana, Mona Jameel; Alshami, Ahlam Mohammad

2016-11-01

Warts in general and plane warts in particular pose a therapeutic challenge for dermatologists. Many treatment modalities exist, with variable success rates, side effect profiles, and precautions. The long-pulsed 532-nm neodymium-doped yttrium aluminium garnet (LP Nd:YAG) laser has not been previously used for this indication. This study was conducted to assess the efficacy and safety of the LP Nd:YAG laser for treating facial plane warts. A total of 160 Yemeni patients (62 women, 98 men; age range, 5-55 years) were exposed to 1 laser treatment session with the following parameters: wavelength, 532 nm; pulse duration, 20 millisecond; spot size, 2 to 3 mm; and fluence, 25 J/cm. The end point was graying or whitening of the lesion. Color photographs were taken before and immediately after treatment and at follow-up visits 1, 4, and 16 weeks after the laser session. An overall clearance rate of 92% after only one session was achieved, with minimal and transient side effects. The LP Nd:YAG laser is safe and effective for treating facial plane warts, with a success rate of 92% after only one session.

Impedance spectroscopy study of SiO2-Li2O:Nd2O3 glasses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pereia, R.; Gozzo, C B; Guedes, I.

2014-01-01

In the present study, neodymium-doped lithium silicate glasses have been prepared by the conventional melt-quenching technique. The dielectric properties, electric modulus and electrical conductivity of SiO2-Li2O (SiLi-0Nd) and SiO2-Li2O:Nd2O3 (SiLi-1.35Nd) have been studied from 1 Hz to 1 MHz in the 333 423 K temperature range. At a given temperature and frequency, we observe that the resistivity increases while the conductivity accordingly decreases when neodymium ions are added to the glass matrix. The activation energy of two distinct regions was evaluated from the ln( dc)=f(1/T) plot and was found to be E1(T<363K)=0.61(0.66)eV and E2(T>363K)=1.26(1.09)eV for SiLi-0Nd (SiLi-1,35Nd). The dielectric constantmore » ( Re) decreases while the dielectric loss (tan ( )) increases under Nd2O3 doping. We also observe that for both glasses, Re and tan ( ) tend to increase with increasing temperature and decrease with increasing frequency.« less

Neodymium: YAG laser damage threshold. A comparison of injection-molded and lathe-cut polymethylmethacrylate intraocular lenses.

PubMed

Wilson, S E; Brubaker, R F

1987-01-01

The possibility that injection-molded intraocular lenses (IOLs) with imperfections called iridescent clefts could have a decreased threshold to neodymium: YAG (Nd:YAG) laser-induced damage was investigated. Thresholds for Nd:YAG laser-induced damage were determined for injection-molded and lathe-cut polymethylmethacrylate lenses. When aimed at a membrane in contact with a posterior convex surface, the average thresholds were 0.96 +/- 0.18 mJ (Standard deviation [SD]) and 1.80 +/- 0.55 mJ, respectively. The difference was significant at P = 0.001. When injection-molding polymethylmethacrylate was used to make lathe-cut IOLs, very few iridescent clefts were present, and the threshold to Nd:YAG laser-induced damage was 0.94 +/- 0.25 mJ. Iridescent clefts are therefore produced during the injection-molding process but they do not lower the threshold to Nd:YAG laser-induced damage. Rather, the reduced threshold in injection-molded lenses is most probably a result of the polymethylmethacrylate used in their manufacture. Clinically, iridescent clefts in a lens suggest that it has been manufactured by an injection-molding process and that Nd:YAG laser posterior capsulotomy must be performed at the lowest possible energy level to avoid damage.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Seung Min; Knight, Travis W.; Voit, Stwart L.

The solid solution of (U1-yFPy)O- 2±x, has the same fluorite structure as UO 2±x lambda, and the lattice parameter is affected by dissolved fission product and oxygen concentrations. We investigated the relation between the lattice parameter and the concentrations of neodymium and oxygen in the fluorite structure of (U 1-yNd y)O 2±x using X-ray diffraction. Moreover, the lattice parameter behavior in the (U 1-yNd y)O 2±x, solid solution shows a linear change as a function of the oxygen-to-metal ratio and solubility of neodymium. The lattice parameter depends on the radii of ions forming the fluorite structure and also can bemore » expressed by a particular rule (modified Vegard's law). Furthermore, the numerical analyses of the lattice parameters for the stoichiometric and nonstoichionietric solid solutions were conducted, and the lattice parameter model for the (U1-yNdy)O 2±x, solid solution was assessed. There is a very linear relationship between the lattice parameter and the Nd and O concentration for the stoichiometry and nonstoichiometry of the (U 1-yNd y)O 2±x solid solution was verified.« less

Clinical and Histopathologic Assessment of Facial Melasma After Low-Fluence Q-Switched Neodymium-Doped Yttrium Aluminium Garnet Laser.

PubMed

Hofbauer Parra, Camila Anna; Careta, Mariana Figueroa; Valente, Neusa Yuriko Sakai; de Sanches Osório, Nuno Eduardo Guimaraes; Torezan, Luis Antonio Ribeiro

2016-04-01

Melasma is a frequent and difficult to treat skin disorder. Results of laser therapy are inconsistent. To determine the safety and efficacy of low-fluence Q-switched neodymium-doped yttrium aluminum garnet (QS Nd:YAG) laser for melasma treatment and assess recurrence rates and histopathologic findings before and after treatment. Twenty patients were treated with 10 weekly sessions of low-fluence 1064-nm QS Nd:YAG laser at 1-week intervals. The modified Melasma Area and Severity Index (mMASI) score was evaluated at baseline; 1 week; and 1, 3, and 6 months after treatment. Epidermal melanin quantification was performed on 10 biopsy samples and compared before and after treatment. All patients showed improvement by mMASI scores, range (21%-75%) compared with that at baseline. No permanent side effects occurred. The recurrence rate was 81%. By histopathology, a slight, nonsignificant (p = .305) decrease in melanin deposition was seen in all layers of the epidermis 1 week after the laser treatments ended. The results confirm the safety and effectiveness of low-fluence QS Nd:YAG laser for treating melasma; however, the high recurrence suggests poor long-term results when the laser is used as a monotherapy.

Interactions of praseodymium and neodymium with nucleosides and nucleotides: absorption difference and comparative absorption spectral study.

PubMed

Misra, S N; Anjaiah, K; Joseph, G; Abdi, S H

1992-02-01

The interactions of praseodymium(III) and neodymium(III) with nucleosides and nucleotides have been studied in different stoichiometry in water and water-DMF mixtures by employing absorption difference and comparative absorption spectrophotometry. The 4f-4f bands were analysed by linear curve analysis followed by gaussian curve analysis, and various spectral parameters were computed, using partial and multiple regression method. The magnitude of changes in both energy interaction and intensity were used to explore the degree of outer and inner sphere coordination, incidence of covalency and the extent of metal 4f-orbital involvement in chemical bonding. Crystalline complexes of the type [Ln(nucleotide)2(H2O)2]- (where nucleotide--GMP or IMP) were characterized by IR, 1H NMR, 31P NMR data. These studies indicated that the binding of the nucleotide is through phosphate oxygen in a bidentate manner and the complexes undergo substantial ionisation in aqueous medium, thereby supporting the observed weak 4f-4f bands and lower values for nephelauxetic effect (1-beta), bonding (b) and covalency (delta) parameters derived from coulombic and spin orbit interaction parameters.

Neodymium(III) Complexes of Dialkylphosphoric and Dialkylphosphonic Acids Relevant to Liquid-Liquid Extraction Systems.

PubMed

Lumetta, Gregg J; Sinkov, Sergey I; Krause, Jeanette A; Sweet, Lucas E

2016-02-15

The complexes formed during the extraction of neodymium(III) into hydrophobic solvents containing acidic organophosphorus extractants were probed by single-crystal X-ray diffractometry, visible spectrophotometry, and Fourier-transform infrared spectroscopy. The crystal structure of the compound Nd(DMP)3 (1, DMP = dimethyl phosphate) revealed a polymeric arrangement in which each Nd(III) center is surrounded by six DMP oxygen atoms in a pseudo-octahedral environment. Adjacent Nd(III) ions are bridged by (MeO)2POO(-) anions, forming the polymeric network. The diffuse reflectance visible spectrum of 1 is nearly identical to that of the solid that is formed when an n-dodecane solution of di(2-ethylhexyl)phosphoric acid (HA) is saturated with Nd(III), indicating a similar coordination environment around the Nd center in the NdA3 solid. The visible spectrum of the HA solution fully loaded with Nd(III) is very similar to that of the NdA3 material, both displaying hypersensitive bands characteristic of an pseudo-octahedral coordination environment around Nd. These spectral characteristics persisted across a wide range of organic Nd concentrations, suggesting that the pseudo-octahedral coordination environment is maintained from dilute to saturated conditions.

Thermodynamic Analysis of Compatibility of Several Reinforcement Materials with Beta Phase NiAl Alloys

NASA Technical Reports Server (NTRS)

Misra, Ajay K.

1988-01-01

Chemical compatibility of several reinforcement materials with beta phase NiAl alloys within the concentration range 40 to 50 at. percent Al have been analyzed from thermodynamic considerations at 1373 and 1573 K. The reinforcement materials considered in this study include carbides, borides, oxides, nitrides, beryllides, and silicides. Thermodynamic data for NiAl alloys have been reviewed and activity of Ni and Al in the beta phase have been derived at 1373 and 1573 K. Criteria for chemical compatibility between the reinforcement material and the matrix have been defined and several chemically compatible reinforcement materials have been defined.

Material comprising two different non-metallic parrticles having different particle sizes for use in solar reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klausner, James F.; Momen, Ayyoub Mehdizadeh; Al-Raqom, Fotouh A.

Disclosed herein is a composite particle comprising a first non-metallic particle in which is dispersed a second non-metallic particle, where the first non-metallic particle and the second non-metallic particle are inorganic; and where a chemical composition of the first non-metallic particle is different from a chemical composition of the second non-metallic particle; and where the first non-metallic particle and the second non-metallic particle are metal oxides, metal carbides, metal nitrides, metal borides, metal silicides, metal oxycarbides, metal oxynitrides, metal boronitrides, metal carbonitrides, metal borocarbides, or a combination thereof.

Plasma-induced damage of tungsten coatings on graphite limiters

NASA Astrophysics Data System (ADS)

Fortuna, E.; Rubel, M. J.; Psoda, M.; Andrzejczuk, M.; Kurzydowski, K. J.; Miskiewicz, M.; Philipps, V.; Pospieszczyk, A.; Sergienko, G.; Spychalski, M.; Zielinski, W.

2007-03-01

Vaccum plasma sprayed tungsten coatings with an evaporated sandwich Re-W interlayer on graphite limiter blocks were studied after the experimental campaign in the TEXTOR tokamak. The coating morphology was modified by high-heat loads and co-deposition of species from the plasma. Co-deposits contained fuel species, carbon, boron and silicon. X-ray diffractometer phase analysis indicated the coexistence of metallic tungsten and its carbides (WC and W2C) and boride (W2B). In the Re-W layer the presence of carbon was detected in a several micrometres thick zone. In the overheated part of the limiter, the Re-W layer was transformed into a sigma phase.

First principle study of UHTC ternary diboride, Cr2AlB2

NASA Astrophysics Data System (ADS)

Rastogi, Anugya; Rajpoot, Priyanka; Verma, U. P.

2018-04-01

In this paper ab-initio study of the structural, electronic and optical properties of ternary metal boride Cr2AlB2 using full potential linear augmented plane wave (FP-LAPW) method based on the density functional theory (DFT). The study of structural properties shows that Cr2AlB2 is metallic in nature and have orthorhombic crystal structure. The optical properties show that it possess anisotropic behavior, which have wide applications in electricity production through concentration of solar power (CSP) technology. To the best of our knowledge, theoretical study of the optical properties of Cr2AlB2 is reported for the first time.

Modeling the mechanical behavior of ceramic and heterophase structures manufactured using selective laser sintering and spark plasma sintering

NASA Astrophysics Data System (ADS)

Skripnyak, Vladimir A.; Skripnyak, Evgeniya G.; Skripnyak, Vladimir V.; Vaganova, Irina K.

A model for predicting mechanical properties of ultra-high temperature ceramics and composites manufactured by selective laser sintering (SLS) and spark plasma sintering (SPS) under shock loading is presented. The model takes into account the porous structure, the specific volume and average sizes of phases, and the temperature of sintering. Residual stresses in ceramic composites reinforced with particles of refractory borides, carbides and nitrides after SLS or SPS were calculated. It is shown that the spall strength of diboride-zirconium matrix composites can be increased by the decreasing of porosity and the introduction of inclusions of specially selected refractory strengthening phases.

Materials for high-temperature thermoelectric conversion

NASA Technical Reports Server (NTRS)

Feigelson, R. S.; Elwell, D.

1983-01-01

High boron materials of high efficiency for thermoelectric power generation and capable of prolonged operation at temperatures over 1200 C are discussed. Background theoretical studies indicated that the low carrier mobility of materials with beta boron and related structures is probably associated with the high density of traps. Experimental work was mainly concerned with silicon borides in view of promising data from European laboratories. A systematic study using structure determination and lattice constant measurements failed to confirm the existence of an SiBn phase. Only SiB6 and a solid solution of silicon in beta boron with a maximum solid solubility of 5.5-6 at % at 1650 C were found.

Laser and solar-photovoltaic space power systems comparison. II.

NASA Technical Reports Server (NTRS)

De Young, R. J.; Stripling, J.; Enderson, T. M.; Humes, D. H.; Davis, W. T.

1984-01-01

A comparison of total system cost is made between solar photovoltaic and laser/receiver systems. The laser systems assume either a solar-pumped CO2 blackbody transfer laser with MHD receiver or a solar pumped liquid neodymium laser with a photovoltaic receiver. Total system costs are less for the laser systems below 300 km where drag is significant. System costs are highly dependent on altitude.

Amazing Vibrations Within the Homopolar Motor

NASA Astrophysics Data System (ADS)

Bednarek, Stanisław

2018-01-01

The most common type of homopolar motor comprises a cylindrical neodymium magnet, a battery, and a non-ferromagnetic frame rotating around the battery. Here, the author substituted a coiled spring for the frame. Due to this change, a new and intriguing effect emerges, the axial buzzing of the spring during its rotation. This paper describes the construction of this motor and explains the reasons for the observed vibrations.

From Desktop Toy to Educational Aid: Neo Magnets as an Alternative to Ball-and-Stick Models in Representing Carbon Fullerenes

ERIC Educational Resources Information Center

Kao, Jacqueline Y.; Yang, Min-Han; Lee, Chi-Young

2015-01-01

Neo magnets are neodymium magnet beads that have been marketed as a desktop toy. We proposed using neo magnets as an alternative building block to traditional ball-and-stick models to construct carbon allotropes, such as fullerene and various nanocone structures. Due to the lack of predetermined physical connections, the versatility of carbon…

Isomorphous rare-earth tris[bis(2,6-diisopropylphenyl) phosphate] complexes and their catalytic properties in 1,3-diene polymerization and in the inhibited oxidation of polydimethylsiloxane.

PubMed

Minyaev, Mikhail E; Tavtorkin, Alexander N; Korchagina, Sof'ya A; Bondarenko, Galina N; Churakov, Andrei V; Nifant'ev, Ilya E

2018-05-01

Crystals of mononuclear tris[bis(2,6-diisopropylphenyl) phosphato-κO]pentakis(methanol-κO)lanthanide methanol monosolvates of lanthanum, [La(C 24 H 34 O 4 P) 3 (CH 3 OH) 5 ]·CH 3 OH, (1), cerium, [Ce(C 24 H 34 O 4 P) 3 (CH 3 OH) 5 ]·CH 3 OH, (2), and neodymium, [Nd(C 24 H 34 O 4 P) 3 (CH 3 OH) 5 ]·CH 3 OH, (3), have been obtained by reactions between LnCl 3 (H 2 O) n (n = 6 or 7) and lithium bis(2,6-diisopropylphenyl) phosphate in a 1:3 molar ratio in methanol media. Compounds (1)-(3) crystallize in the monoclinic P2 1 /c space group and have isomorphous crystal structures. All three bis(2,6-diisopropylphenyl) phosphate ligands display a κO-monodentate coordination mode. The coordination number of the metal atom is 8. Each [Ln{O 2 P(O-2,6- i Pr 2 C 6 H 3 ) 2 } 3 (CH 3 OH) 5 ] molecular unit exhibits four intramolecular O-H...O hydrogen bonds, forming six-membered rings. The unit forms two intermolecular O-H...O hydrogen bonds with one noncoordinating methanol molecule. All six hydroxy H atoms are involved in hydrogen bonding within the [Ln{O 2 P(O-2,6- i Pr 2 C 6 H 3 ) 2 } 3 (CH 3 OH) 5 ]·CH 3 OH unit. This, along with the high steric hindrance induced by the three bulky diaryl phosphate ligands, prevents the formation of a hydrogen-bond network. Complexes (1)-(3) exhibit disorder of two of the isopropyl groups of the phosphate ligands. The cerium compound (2) demonstrates an essential catalytic inhibition in the thermal decomposition of polydimethylsiloxane in air at 573 K. Catalytic systems based on the neodymium complex tris[bis(2,6-diisopropylphenyl) phosphato-κO]neodymium, (3'), which was obtained as a dry powder of (3) upon removal of methanol, display a high catalytic activity in isoprene and butadiene polymerization.

Rare Earth Element Concentrations in Geothermal Wells at the Puna Geothermal Field, Hawaii

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fowler, Andrew; Zierenberg, Robert

Rare earth element concentrations in the geothermal wells at the Puna geothermal field, Hawaii. Samples taken from geothermal wells KS-5, KS-6W, KS-9W, KS-14E, and KS-16N. Includes pH and concentrations for Cerium, Dysprosium, Erbium, Europium, Gadolinium, Holmium, Lanthanum, Lutetium, Neodymium, Praseodymium, Samarium, Terbium, Thulium, Yttrium, and Ytterbium. Samples collected on November 11-17, 2016.

Metallic glass composition. [That does not embrittle upon annealing

DOEpatents

Kroeger, D.M.; Koch, C.C.

1984-09-14

This patent pertains to a metallic glass alloy that is either iron-based or nickel-based or based on a mixture of iron and nickel, containing lesser amounts of elements selected from the group boron, silicon, carbon and phosphorous to which is added an amount of a ductility-enhancing element selected from the group cerium, lanthanum, praseodymium and neodymium sufficient to increase ductility of the metallic glass upon annealing.

US Army Institute of Dental Research Annual Progress Report FY80.

DTIC Science & Technology

1980-10-01

indicates that use of the laser technique does result in increased connectiv tissue regeneration and improved resolution of the periodontal defects...connectiv tissue regeneration and improved resolution of the periodontal defects. Final analysis of histologic data on the use of the neodymium laser for in...and 21 Bone Regeneration in Trnumatic Wounds (Pathology) DA OH 6038 Development of Endodontic Procedures for 22 Military Dentistry ( Oral Biology) DA OK

JPRS Report, Science & Technology USSR: Chemistry

DTIC Science & Technology

1991-08-12

KH1M1CHESKIKHNAUK No 1 , Jan-Feb 91] 18 Synthesis of Neodymium Silicates and Glass Prepared From Them by Laser Irradiation of Co-Precipitated...KHIMICHESKIY ZHURNAL No 1 , Jan-Feb 91] 28 Synthesis and Investigation of Antiarrhythmic Activity of Alkoxyaminoalcohol Salts of Cyclohexane Series [N.S...Catalysts in Organic Synthesis . Communication 25. Synthesis of Polymer Supported Tetrazols 917M0091D Riga LATVIYSKIY KHIMICHESKIY ZHURNAL in Russian No 1

Laser treatment of a neodymium magnet and analysis of surface characteristics

NASA Astrophysics Data System (ADS)

Yilbas, B. S.; Ali, H.; Rizwan, M.; Kassas, M.

2016-08-01

Laser treatment of neodymium magnet (Nd2Fe14B) surface is carried out under the high pressure nitrogen assisting gas. A thin carbon film containing 12% WC carbide particles with 400 nm sizes are formed at the surface prior to the laser treatment process. Morphological and metallurgical changes in the laser treated layer are examined using the analytical tools. The corrosion resistance of the laser treated surface is analyzed incorporating the potentiodynamic tests carried out in 0.05 M NaCl+0.1 M H2SO4 solution. The friction coefficient of the laser treated surface is measured using the micro-scratch tester. The wetting characteristics of the treated surface are assessed incorporating the sessile water drop measurements. It is found that a dense layer consisting of fine size grains and WC particles is formed in the surface region of the laser treated layer. Corrosion resistance of the surface improves significantly after the laser treatment process. Friction coefficient of laser treated surface is lower than that of the as received surface. Laser treatment results in superhydrophobic characteristics at the substrate surface. The formation of hematite and grain size variation in the treated layer slightly lowers the magnetic strength of the laser treated workpiece.

The Effect of Neodymium: Yttrium Aluminum Garnet and Fractional Carbon Dioxide Lasers on Alopecia Areata: A Prospective Controlled Clinical Trial.

PubMed

Yalici-Armagan, Basak; Elcin, Gonca

2016-04-01

Effective treatment options for alopecia areata (AA) are missing. Whether lasers might be effective is a topic of debate. We aimed to evaluate whether neodymium: yttrium aluminum garnet (Nd:YAG) or fractional carbon dioxide lasers might stimulate the development of new hair. Thirty-two patients who had long-standing and treatment refractory diseases were recruited for the study. Three different patches on the scalp were selected, 1 of which served as control. The mean outcome measure was the hair count, which was calculated with the digital phototrichogram. Response was defined as at least 25% increase in the mean hair count at the treated patch compared with the control patch. At the end of the study, there was no statistically significant difference in the mean hair count for the 3 patches. In 7 of 32 patients (22%), an increase in the mean hair count was observed on the whole scalp including the control patch, which resulted in an improved Severity of Alopecia Tool (SALT) score. We have observed that Nd:YAG or fractional carbon dioxide lasers did not increase the mean hair count on the treated AA patches when compared with the control patch. However, an SALT score improvement in 22% of the patients suggested spontaneous remission.

Deglacial variability of Antarctic Intermediate Water penetration into the North Atlantic from authigenic neodymium isotope ratios

NASA Astrophysics Data System (ADS)

Xie, Ruifang C.; Marcantonio, Franco; Schmidt, Matthew W.

2012-09-01

Understanding intermediate water circulation across the last deglacial is critical in assessing the role of oceanic heat transport associated with Atlantic Meridional Overturning Circulation variability across abrupt climate events. However, the links between intermediate water circulation and abrupt climate events such as the Younger Dryas (YD) and Heinrich Event 1 (H1) are still poorly constrained. Here, we reconstruct changes in Antarctic Intermediate Water (AAIW) circulation in the subtropical North Atlantic over the past 25 kyr by measuring authigenic neodymium isotope ratios in sediments from two sites in the Florida Straits. Our authigenic Nd isotope records suggest that there was little to no penetration of AAIW into the subtropical North Atlantic during the YD and H1. Variations in the northward penetration of AAIW into the Florida Straits documented in our authigenic Nd isotope record are synchronous with multiple climatic archives, including the Greenland ice core δ18O record, the Cariaco Basin atmosphere Δ14C reconstruction, the Bermuda Rise sedimentary Pa/Th record, and nutrient and stable isotope data from the tropical North Atlantic. The synchroneity of our Nd records with multiple climatic archives suggests a tight connection between AAIW variability and high-latitude North Atlantic climate change.

Concomitant Leaching and Electrochemical Extraction of Rare Earth Elements from Monazite.

PubMed

Maes, Synthia; Zhuang, Wei-Qin; Rabaey, Korneel; Alvarez-Cohen, Lisa; Hennebel, Tom

2017-02-07

Rare earth elements (REEs) have become increasingly important in modern day technologies. Unfortunately, their recycling is currently limited, and the conventional technologies for their extraction and purification are exceedingly energy and chemical intensive. New sustainable technologies for REE extraction from both primary and secondary resources would be extremely beneficial. This research investigated a two-stage recovery strategy focused on the recovery of neodymium (Nd) and lanthanum (La) from monazite ore that combines microbially based leaching (using citric acid and spent fungal supernatant) with electrochemical extraction. Pretreating the phosphate-based monazite rock (via roasting) dramatically increased the microbial REE leaching efficiency. Batch experiments demonstrated the effective and continued leaching of REEs by recycled citric acid, with up to 392 mg of Nd L -1 and 281 mg of La L -1 leached during seven consecutive 24 h cycles. Neodymium was further extracted in the catholyte of a three-compartment electrochemical system, with up to 880 mg of Nd L -1 achieved within 4 days (at 40 A m -2 ). Meanwhile, the radioactive element thorium and counterions phosphate and citrate were separated effectively from the REEs in the anolyte, favoring REE extraction and allowing sustainable reuse of the leaching agent. This study shows a promising technology that is suitable for primary ores and can further be optimized for secondary resources.

Extraction of Lanthanide and Actinide Ions from Aqueous Mixtures Using a Carboxylic Acid-Functionalized Porous Aromatic Framework

DOE PAGES

Demir, Selvan; Brune, Nicholas K.; Van Humbeck, Jeffrey F.; ...

2016-04-08

Porous aromatic frameworks (PAFs) incorporating a high concentration of acid functional groups possess characteristics that are promising for use in separating lanthanide and actinide metal ions, as required in the treatment of radioactive waste. These materials have been shown to be indefinitely stable to concentrated acids and bases, potentially allowing for multiple adsorption/stripping cycles. Additionally, the PAFs combine exceptional features from MOFs and inorganic/ activated carbons giving rise to tunable pore surfaces and maximum chemical stability. Herein, we present a study of the adsorption of selected metal ions, Sr 2+, Fe 3+, Nd 3+, and Am 3+, from aqueous solutionsmore » employing a carbon-based porous aromatic framework, BPP-7 (Berkeley Porous Polymer-7). This material displays high metal loading capacities together with excellent adsorption selectivity for neodymium over strontium based on Langmuir adsorption isotherms and ideal adsorbed solution theory (IAST) calculations. Based in part upon X-ray absorption spectroscopy studies, the stronger adsorption of neodymium is attributed to multiple metal ion and binding site interactions resulting from the densely functionalized and highly interpenetrated structure of BPP-7. Finally, recyclability and combustibility experiments demonstrate that multiple adsorption/stripping cycles can be completed with minimal degradation of the polymer adsorption capacity.« less

Lattice Parameter Behavior with Different Nd and O Concentrations in (U 1-yNd y)O 2±x Solid Solution

DOE PAGES

Lee, Seung Min; Knight, Travis W.; Voit, Stwart L.; ...

2016-02-02

The solid solution of (U1-yFPy)O- 2±x, has the same fluorite structure as UO 2±x lambda, and the lattice parameter is affected by dissolved fission product and oxygen concentrations. We investigated the relation between the lattice parameter and the concentrations of neodymium and oxygen in the fluorite structure of (U 1-yNd y)O 2±x using X-ray diffraction. Moreover, the lattice parameter behavior in the (U 1-yNd y)O 2±x, solid solution shows a linear change as a function of the oxygen-to-metal ratio and solubility of neodymium. The lattice parameter depends on the radii of ions forming the fluorite structure and also can bemore » expressed by a particular rule (modified Vegard's law). Furthermore, the numerical analyses of the lattice parameters for the stoichiometric and nonstoichionietric solid solutions were conducted, and the lattice parameter model for the (U1-yNdy)O 2±x, solid solution was assessed. There is a very linear relationship between the lattice parameter and the Nd and O concentration for the stoichiometry and nonstoichiometry of the (U 1-yNd y)O 2±x solid solution was verified.« less

Scenarios for Demand Growth of Metals in Electricity Generation Technologies, Cars, and Electronic Appliances

PubMed Central

2018-01-01

This study provides scenarios toward 2050 for the demand of five metals in electricity production, cars, and electronic appliances. The metals considered are copper, tantalum, neodymium, cobalt, and lithium. The study shows how highly technology-specific data on products and material flows can be used in integrated assessment models to assess global resource and metal demand. We use the Shared Socio-economic Pathways as implemented by the IMAGE integrated assessment model as a starting point. This allows us to translate information on the use of electronic appliances, cars, and renewable energy technologies into quantitative data on metal flows, through application of metal content estimates in combination with a dynamic stock model. Results show that total demand for copper, neodymium, and tantalum might increase by a factor of roughly 2 to 3.2, mostly as a result of population and GDP growth. The demand for lithium and cobalt is expected to increase much more, by a factor 10 to more than 20, as a result of future (hybrid) electric car purchases. This means that not just demographics, but also climate policies can strongly increase metal demand. This shows the importance of studying the issues of climate change and resource depletion together, in one modeling framework. PMID:29533657

Scenarios for Demand Growth of Metals in Electricity Generation Technologies, Cars, and Electronic Appliances.

PubMed

Deetman, Sebastiaan; Pauliuk, Stefan; van Vuuren, Detlef P; van der Voet, Ester; Tukker, Arnold

2018-04-17

This study provides scenarios toward 2050 for the demand of five metals in electricity production, cars, and electronic appliances. The metals considered are copper, tantalum, neodymium, cobalt, and lithium. The study shows how highly technology-specific data on products and material flows can be used in integrated assessment models to assess global resource and metal demand. We use the Shared Socio-economic Pathways as implemented by the IMAGE integrated assessment model as a starting point. This allows us to translate information on the use of electronic appliances, cars, and renewable energy technologies into quantitative data on metal flows, through application of metal content estimates in combination with a dynamic stock model. Results show that total demand for copper, neodymium, and tantalum might increase by a factor of roughly 2 to 3.2, mostly as a result of population and GDP growth. The demand for lithium and cobalt is expected to increase much more, by a factor 10 to more than 20, as a result of future (hybrid) electric car purchases. This means that not just demographics, but also climate policies can strongly increase metal demand. This shows the importance of studying the issues of climate change and resource depletion together, in one modeling framework.

Dynamic photopatterning of cells in situ by Q-switched neodymium-doped yttrium ortho-vanadate laser.

PubMed

Deka, Gitanjal; Okano, Kazunori; Kao, Fu-Jen

2014-01-01

Cellular micropattering has been increasingly adopted in quantitative biological experiments. A Q-switched pulsed neodymium-doped yttrium ortho-vanadate (Nd∶YVO4) laser directed in-situ microfabrication technique for cell patterning is presented. A platform is designed uniquely to achieve laser ablation. The platform is comprised of thin gold coating over a glass surface that functions as a thermal transducer and is over-layered by a cell repellant polymer layer. Micropatterns are engraved on the platform, subsequently exposing specific cell adhesive micro-domains by ablating the gold-polymer coating photothermally. Experimental results indicate that the proposed approach is applicable under culture conditions, viable toward cells, and has a higher engraving speed. Possible uses in arraying isolated single cells on the platform are also shown. Additionally, based on those micro-patterns, dynamic cellular morphological changes and migrational speed in response to geometrical barriers are studied to demonstrate the potential applications of the proposed approach. Our results further demonstrate that cells in narrower geometry had elongated shapes and higher migrational speed than those in wider geometry. Importantly, the proposed approach will provide a valuable reference for efforts to study single cell dynamics and cellular migration related processes for areas such as cell division, wound healing, and cancer invasion.

The Influence of Lactic Acid Concentration on the Separation of Light Rare Earth Elements by Continuous Liquid-Liquid Extraction with 2-Ethylhexyl Phosphonic Acid Mono-2-ethylhexyl Ester

NASA Astrophysics Data System (ADS)

de Carvalho Gomes, Rafael; Seruff, Luciana Amaral; Scal, Maira Labanca Waineraich; Vera, Ysrael Marrero

2018-02-01

The separation of rare earth elements (REEs) using solvent extraction adding complexing agents appears to be an alternative to saponification of the extractant. We evaluated the effect of lactic acid concentration on didymium (praseodymium and neodymium) and lanthanum extraction with 2-ethylhexyl phosphonic acid mono-2-ethyl hexyl ester [HEH(EHP)] as extractant. First, we investigated in batch experiments the separation of lanthanum (La) and didymium (Pr and Nd) using McCabe-Thiele diagrams to estimate the number of extraction stages when the feed solution was or was not conditioned with lactic acid. Additionally, we conducted continuous liquid-liquid extraction experiments and evaluated the influence of lactic acid concentration on the REE extraction and separation. The tests showed that the extraction percentage of REEs and the separation factor Pr/La increased when the lactic acid concentration increased, but the didymium purity decreased. Lanthanum, praseodymium, and neodymium extraction rate were 23.0, 89.7, and 99.2 pct, respectively, with 1:1 aqueous/organic volume flow rate and feed solution doped with 0.52 mol L-1 lactic acid. The highest didymium purity reached was 92.0 pct with 0.26 mol L-1 lactic acid concentration.

Determination of trace amounts of rare-earth elements in highly pure neodymium oxide by sector field inductively coupled plasma mass spectrometry (ICP-SFMS) and high-performance liquid chromatography (HPLC) techniques

NASA Astrophysics Data System (ADS)

Pedreira, W. R.; Sarkis, J. E. S.; da Silva Queiroz, C. A.; Rodrigues, C.; Tomiyoshi, I. A.; Abrão, A.

2003-02-01

Recently rare-earth elements (REE) have received much attention in fields of geochemistry and industry. Rapid and accurate determinations of them are increasingly required as industrial demands expand. Sector field inductively coupled plasma mass spectrometry (ICP-SFMS) with high-performance liquid chromatography (HPLC) has been applied to the determination of REE. HR ICP-MS was used as an element-selective detector for HPLC in highly pure materials. The separation of REE with HPLC helped to avoid erroneous analytical results due to spectral interferences. Sixteen elements (Sc, Y and 14 lanthanides) were determined selectively with the HPLC/ICP-SFMS system using a concentration gradient methods. The detection limits with the HPLC/ICP-SFMS system were about 0.5-10 pg mL-1. The percentage recovery ranged from 90% to 100% for different REE. The %RSD of the methods varying between 2.5% and 4.5% for a set of five (n=5) replicates was found for the IPEN's material and for the certificate reference sample. Determination of trace REEs in two highly pure neodymium oxides samples (IPEN and Johnson Matthey Company) were performed. In short, the IPEN's materials which are highly pure (>99.9%) were successfully analyzed without spectral interferences.

Di-μ-but-2-enoato-bis­[diaqua­bis(but-2-enoato)neodymium(III)] 2,6-diamino­purine disolvate

PubMed Central

Atria, Ana María; Astete, Alan; Garland, Maria Teresa; Baggio, Ricardo

2011-01-01

The title Nd complex [Nd2(C4H5O2)6(H2O)4]·2C5H6N6 is isotypic with two previously reported Dy and Ho isologues. It is composed of [Nd(crot)3(H2O)2]2 dimers [crot(onate) = but-2-enoate = C4H5O2], built up around symmetry centres and completed by 2,6-diamine­purine mol­ecules acting as solvates. The neodymium cations are coordinated by three chelating crotonato units and two water mol­ecules. One of the chelating carboxyl­ates acts also in a bridging mode, sharing one oxygen with both cations, and the final result is a pair of NdO9 tricapped prismatic polyhedra linked to each other through a central (Nd—O)2 loop. A most attractive aspect of the structures resides in the existence of a complex inter­molecular hydrogen-bonding interaction scheme involving two sets of tightly inter­linked, non-inter­secting one-dimensional structures, one of them formed by the [Nd(crot)3(H2O)2]2 dimers running along [100] and the second by the solvate mol­ecules evolving along [010]. PMID:22058842

Optical radiation hazards of laser welding processes. Part 1: Neodymium-YAG laser.

PubMed

Rockwell, R J; Moss, C E

1983-08-01

High power laser devices are being used for numerous metalworking processes such as welding, cutting and heat treating. Such laser devices are totally enclosed either by the manufacturer or the end-user. When this is done, the total laser system is usually certified by the manufacturer following the federal requirements of the Code of Federal Regulations (CFR) 1040.10 and 10.40.11 as a Class I laser system. Similarly, the end-user may also reclassify an enclosed high-power laser into the Class I category following the requirements of the American National Standards Institute (ANSI) Z-136.1 (1980) standard. There are, however, numerous industrial laser applications where Class IV systems are required to be used in an unenclosed manner. In such applications, there is concern for both ocular and skin hazards caused by direct and scattered laser radiation, as well as potential hazards caused by the optical radiation created by the laser beam's interaction with the metal (i.e. the plume radiation). Radiant energy measurements are reported for both the scattered laser radiation and the resultant plume radiations which were produced during typical unenclosed Class IV Neodymium-YAG laser welding processes. Evaluation of the plume radiation was done with both radiometric and spectroradiometric measurement equipment. The data obtained were compared to applicable safety standards.

Effect of laser peripheral iridotomy using argon and neodymium-YAG lasers on corneal endothelial cell density: 7-year longitudinal evaluation.

PubMed

Ono, Takashi; Iida, Masaharu; Sakisaka, Toshihiro; Minami, Keiichiro; Miyata, Kazunori

2018-03-01

To evaluate the changes in corneal endothelial cell density (ECD) over a 7-year period after laser peripheral iridotomy (LPI) using argon and neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers. Retrospective case series. Eyes that underwent prophylactic LPI using argon and Nd:YAG lasers were followed up for 7 years. Central corneal endothelial cells were observed by use of noncontact specular microscopy preoperatively and at 1 and 7 years postoperatively. Changes in ECD and the associations between preoperative ECD and the total energy of the Nd:YAG laser were evaluated. Fifty-one eyes of 51 patients were followed up for 7 years. The ECD significantly decreased after LPI (P < 0.049), and the reduction rate at 1 year after the surgery (1.69 ± 4.80%, 95% CI: 0.34%-3.04%) was significantly higher than the annual reduction rates after 1 year (0.17 ± 0.85%/y, P = 0.036, 95% CI: -0.07% to 0.41%). No association was found between the preoperative ECD and the total laser energy. Long-term evaluation indicated that the reduction in ECD after argon-Nd:YAG laser LPI was present but small during the initial year and was negligible after 1 year.

Extraction of Lanthanide and Actinide Ions from Aqueous Mixtures Using a Carboxylic Acid-Functionalized Porous Aromatic Framework

PubMed Central

2016-01-01

Porous aromatic frameworks (PAFs) incorporating a high concentration of acid functional groups possess characteristics that are promising for use in separating lanthanide and actinide metal ions, as required in the treatment of radioactive waste. These materials have been shown to be indefinitely stable to concentrated acids and bases, potentially allowing for multiple adsorption/stripping cycles. Additionally, the PAFs combine exceptional features from MOFs and inorganic/activated carbons giving rise to tunable pore surfaces and maximum chemical stability. Herein, we present a study of the adsorption of selected metal ions, Sr2+, Fe3+, Nd3+, and Am3+, from aqueous solutions employing a carbon-based porous aromatic framework, BPP-7 (Berkeley Porous Polymer-7). This material displays high metal loading capacities together with excellent adsorption selectivity for neodymium over strontium based on Langmuir adsorption isotherms and ideal adsorbed solution theory (IAST) calculations. Based in part upon X-ray absorption spectroscopy studies, the stronger adsorption of neodymium is attributed to multiple metal ion and binding site interactions resulting from the densely functionalized and highly interpenetrated structure of BPP-7. Recyclability and combustibility experiments demonstrate that multiple adsorption/stripping cycles can be completed with minimal degradation of the polymer adsorption capacity. PMID:27163056

Laboratory and clinical experience with neodymium:YAG laser prostatectomy

NASA Astrophysics Data System (ADS)

Kabalin, John N.

1996-05-01

Since 1991, we have undertaken extensive laboratory and clinical studies of the Neodymium:YAG (Nd:YAG) laser for surgical treatment of bladder outlet obstruction due to prostatic enlargement or benign prostatic hyperplasia (BPH). Side-firing optical fibers which emit a divergent, relatively low energy density Nd:YAG laser beam produce coagulation necrosis of obstructing periurethral prostate tissue, followed by gradual dissolution and slough in the urinary stream. Laser-tissue interactions and Nd:YAG laser dosimetry for prostatectomy have been studied in canine and human prostate model systems, enhancing clinical application. Ongoing studies examine comparative Nd:YAG laser dosimetry for various beam configurations produced by available side-firing optical fibers and continue to refine operative technique. We have documented clinical outcomes of Nd:YAG laser prostatectomy in 230 consecutive patients treated with the UrolaseTM side-firing optical fiber. Nd:YAG laser coagulation the prostate produces a remarkably low acute morbidity profile, with no significant bleeding or fluid absorption. No postoperative incontinence has been produced. Serial assessments of voiding outcomes over more than 3 years of followup show objective and symptomatic improvement following Nd:YAG laser prostatectomy which is comparable to older but more morbid electrosurgical approaches. Nd:YAG laser prostatectomy is a safe, efficacious, durable and cost-effective treatment for BPH.

Charge transfer in rare earth oxide hybrid solar cells revealed through ultrafast spectroscopic measurement

NASA Astrophysics Data System (ADS)

Pandit, Bill; Fernando, Kasun; Alphenaar, Bruce; Liu, Jinjun

2014-03-01

Hybrid inorganic-organic solar cells typically combine a transition metal oxide (such as TiO2) and organic dye or polymer absorber to form the donor acceptor pair. Here, Oxidized neodymium (Nd2O3) particles are combined with [6,6]-Phenyl C61 butyric acid methyl ester (PCBM) to form the active layer of a bulk heterojunction solar cell. The addition of the Nd2O3 results in an enhancement in the short circuit current and open circuit voltage compared to pure PCBM. We also studied the ultrafast dynamics of photoexcitation in pristine PCBM film, and their blends with the rare earth oxide neodymium particles using the pump-probe photomodulation (PM) spectroscopy with ~30 fs time resolution. Our transient PM spectrum covers spectral range of 430 nm to 730 nm. Although the spectra of Nd2O3/PCBM are very similar with pristine PCBM, the recombination kinetics of photogenerated excitons decay rate increases with the addition of Nd2O3, and ground state photobleaching is also observed. Taken together this provides evidence for the charge transfer between the organic and rare earth inorganic components. Supported by the DOE-EPSCoR fund DOE BES (DE-FG02-07ER46375) at University of Louisville.

The stable and water-soluble neodymium-doped lanthanide fluoride nanoparticles for near infrared probing of copper ion.

PubMed

Xue, Fang-Min; Wang, He-Fang

2012-09-15

Neodymium (Nd(3+)) doped nanomaterials exhibited the unique near infrared (NIR) luminescence properties. However, the application of Nd-doped nanomaterials to chemosensors was rarely explored. Herein, the water-soluble 2-aminoethyl dihydrogen phosphate stabilized Nd-doped LaF(3) (ADP-Nd-LaF(3)) nanoparticles were explored as the NIR probe for chemosensors. The NIR emission intensity at 1061 nm of ADP-Nd-LaF(3) nanoparticles kept stable in the aqueous solution of various pH and coexisting of most common metal ions except copper ion, consequently, the ADP-Nd-LaF(3) nanoparticles were developed as a high selective NIR probe for Cu(II). The NIR emission of ADP-Nd-LaF(3) exhibits a linear quenching response to Cu(II) in the range 5-100 μM, with a detection limit of 0.8 μM. The precision of eleven replicate detections of 5 μM Cu(II) was 0.5% (RSD). The recovery of spiked Cu(II) in human urine and waste water samples ranged from 102 to 109%. The possible mechanism of Cu(II)-induced fluorescence quenching of ADP-Nd-LaF(3) nanoparticles was also discussed. Copyright © 2012 Elsevier B.V. All rights reserved.

Formation of Maximum Eddy Current Force by Non Ferrous Materials

NASA Astrophysics Data System (ADS)

Kader, M. M. A.; Razali, Z. B.; Yasin, N. S. M.; Daud, M. H.

2018-03-01

This project is concerned with the study of eddy current effects on various materials such as aluminum, copper and magnesium. Two types of magnets used in this study; magnetic ferrite (ZnFe+2O4) and magnetic neodymium (NdFeBN42). Eddy current force will be exerted to these materials due to current flows along the magnet. This force depends on the type of magnet, type of material and the gap between the magnet and the material or between the two magnets. The results show that at constant magnet to material gap, the eddy current force decreases as the magnet to magnet gap increases. Similarly, at constant magnet to magnet gap, the eddy current force decreases as the magnet to material gap increases. The minimum force was achieved when the gap of magnet to material is maximum, similarly to the gap of magnet to magnet. The weakest force was between Copper and Neodymium at a magnet to material gap of 20 mm and magnet to magnet gap of 40 mm; the eddy current force was 0.00048 N. The strongest force (maximum) was between Magnesium and Ferrite and 0.42273 N at a magnet to material gap of 3 mm and magnet to magnet gap of 5 mm.

Rhenium-osmium and samarium-neodymium isotopic systematics of the stillwater complex

USGS Publications Warehouse

Lambert, D.D.; Morgan, J.W.; Walker, R.J.; Shirey, S.B.; Carlson, R.W.; Zientek, M.L.; Koski, M.S.

1989-01-01

Isotopic data for the Stillwater Complex, Montana , which formed about 2700 Ma (million years ago), were obtained to evaluate the role of magma mixing in the formation of strategic platinum-group element (PGE) ore deposits. Neodymium and osmium isotopic data indicate that the intrusion formed from at least two geochemically distinct magmas. Ultramafic affinity (U-type) magmas had initial ??Nd of -0.8 to -3.2 and a chondritic initial 187Os/186Os ratio of ???0.88, whereas anorthositic affinity (A-type) magmas had ??Nd of -0.7 to +1.7 and an initial 187Os/186Os ratio of ???1.13. These data suggest that U-type magmas were derived from a lithospheric mantle source containing recycled crustal materials whereas A-type magmas originated either by crustal contamination of basaltic magmas or by partial melting of basalt in the lower crust. The Nd and Os isotopic data also suggest that Os, and probably the other PGEs in ore horizons such as the J-M Reef, was derived from A-type magmas. The Nd and Os isotopic heterogeneity observed in rocks below the J-M Reef also suggests that A-type magmas were injected into the Stillwater U-type magma chamber at several stages during the development of the Ultramafic series.

Numerical and experimental study of electron-beam coatings with modifying particles FeB and FeTi

NASA Astrophysics Data System (ADS)

Kryukova, Olga; Kolesnikova, Kseniya; Gal'chenko, Nina

2016-07-01

An experimental study of wear-resistant composite coatings based on titanium borides synthesized in the process of electron-beam welding of components thermo-reacting powders are composed of boron-containing mixture. A model of the process of electron beam coating with modifying particles of boron and titanium based on physical-chemical transformations is supposed. The dissolution process is described on the basis of formal kinetic approach. The result of numerical solution is the phase and chemical composition of the coating under nonequilibrium conditions, which is one of the important characteristics of the coating forming during electron beam processing. Qualitative agreement numerical calculations with experimental data was shown.

A new superhard material: Osmium diboride OsB 2

NASA Astrophysics Data System (ADS)

Hebbache, M.; Stuparević, L.; Živković, D.

2006-08-01

Superhard materials have many industrial applications, wherever resistance to abrasion and wear are important. The synthesis of new superhard materials is one of the great challenges to scientists. We re-examined the phase diagram of the binary osmium-boron system and confirmed the existence of two hexagonal phases, OsB 1.1, Os 2B 3, and an orthorhombic phase, OsB 2. Almost nothing is known about the physical properties of osmium borides. Microhardness measurements show that OsB 2 is extremely hard. Ab initio calculations show that this is due to formation of covalent bonds between boron atoms. OsB 2 is also a low compressibility material. It can be used as hard coating.

First-principles study of low compressibility osmium borides

NASA Astrophysics Data System (ADS)

Gou, Huiyang; Hou, Li; Zhang, Jingwu; Li, Hui; Sun, Guifang; Gao, Faming

2006-05-01

Using first-principles total energy calculations we investigate the structural, elastic, and electronic properties of OsB2 and OsB, respectively. The calculated equilibrium structural parameters of OsB2 are in agreement with the available experimental results. The calculations indicate that OsB in tungsten carbide is more energetically stable under the ambient condition than the metastable cesium chloride phase of OsB. Results of bulk modulus show that they are potential low compressible materials. The hardness of OsB2 is estimated by employing a semiempirical theory. The results indicate that OsB2 is an ultraincompressible material, but not a superhard material. The method designing superhard materials is different from one creating ultraincompressible materials.

The friction and wear properties of sputtered hard refractory compounds

NASA Technical Reports Server (NTRS)

Brainard, W. A.

1978-01-01

Several refractory silicide, boride, and carbide coatings were examined. The coatings were applied to type 440C steel surfaces by radio-frequency sputtering. The friction and wear properties of the coatings were found to be related to stoichiometry and impurity content of the bulk coating as well as the degree of interfacial adherence between coating and substrate. Bulk coating stoichiometry could to a large extent be controlled by the application of a negative bias voltage during deposition. Adherence was promoted by the formation of an oxidized layer at the interface. Deliberate preoxidizing of the 440C produced enhanced adherence for many compounds which are related to the formation of a mixed oxide transition region.

Passivating overcoat bilayer for multilayer reflective coatings for extreme ultraviolet lithography

DOEpatents

Montcalm, Claude; Stearns, Daniel G.; Vernon, Stephen P.

1999-01-01

A passivating overcoat bilayer is used for multilayer reflective coatings for extreme ultraviolet (EUV) or soft x-ray applications to prevent oxidation and corrosion of the multilayer coating, thereby improving the EUV optical performance. The overcoat bilayer comprises a layer of silicon or beryllium underneath at least one top layer of an elemental or a compound material that resists oxidation and corrosion. Materials for the top layer include carbon, palladium, carbides, borides, nitrides, and oxides. The thicknesses of the two layers that make up the overcoat bilayer are optimized to produce the highest reflectance at the wavelength range of operation. Protective overcoat systems comprising three or more layers are also possible.

Assessment of the State of the Art of Ultra High Temperature Ceramics

NASA Technical Reports Server (NTRS)

Johnson, Sylvia; Gasch, Matt; Stackpoole, Mairead

2009-01-01

Ultra High Temperature Ceramics (UHTCs) are a family of materials that includes the borides, carbides and nitrides of hafnium-, zirconium- and titanium-based systems. UHTCs are famous for possessing some of the highest melting points of known materials. In addition, they are very hard, have good wear resistance, mechanical strength, and relatively high thermal conductivities (compared to other ceramic materials). Because of these attributes, UHTCs are ideal for thermal protection systems, especially those that require chemical and structural stability at extremely high operating temperatures. UHTCs have the potential to revolutionize the aerospace industry by enabling the development of sharp hypersonic vehicles or atmospheric entry probes capable of the most extreme entry conditions.

Identification of novel sulfur-containing steroids in sediments and petroleum: probable incorporation of sulfur into δ 5,7-sterols during early diagenesis

NASA Astrophysics Data System (ADS)

Sinninghe Damsté, Jaap S.; Schouten, Stefan; de Leeuw, Jan W.; van Duin, Adri C. T.; Geenevasen, Jan A. J.

1999-01-01

A novel sulfur-containing sterane, 4α,7α-epithio-5β-cholestane, has been identified in a sediment extract from the Miocene Northern Apennines marl (Italy) after its isolation by column chromatography and high pressure liquid chromatography. The compound has been characterised by GC-MS and mild Nickel boride desulfurisation and one and two-dimensional 1H NMR techniques. C 27-C 29 homologs have been detected in sediment extracts of three different formations and in one petroleum sample. These sulfur-containing steroids are probably formed by an intramolecular reaction of inorganic sulfides with early diagenetic products of Δ 5,7-sterols.

Thermodynamic properties of rare earth elements in La-RE-Ga-In alloys (RE = Nd, Y)

NASA Astrophysics Data System (ADS)

Raguzina, Ekaterina V.; Maltsev, Dmitry S.; Volkovich, Vladimir A.; Yamshchikov, Leonid F.; Chukin, Andrey V.

2017-09-01

Thermodynamic properties of La, Nd, and Y were studied in pseudo-quaternary systems La-Nd-(Ga-In)eut and La-Y-(Ga-In)eut. Temperature dependences of lanthanum, neodymium, and yttrium activity in the alloys were determined at 300-800 °C employing the e.m.f. method. Partial thermodynamic functions of lanthanum in the alloys studied were calculated on the basis of the experimental data.

Low threshold CW Nc laser oscillator at 1060 nm study

NASA Technical Reports Server (NTRS)

Birnbaum, M.; Deshazer, L. G.

1976-01-01

A broad range of characteristics of neodymium/yag lasers were investigated. With Nd:YVO4 crystals, CW 1.06 mu lasers were operated with thresholds a factor of 2 lower than Nd:YAG and with greater slope efficiencies. Thus, the first step in the development of new oscillators suitable for application in high data rate laser communication systems which surpass the present performance of the Nd:YAG laser has been successfully demonstrated.

Preparation and Characterization of High Temperature Superconductor Film Surfaces

DTIC Science & Technology

1993-10-27

Lanthanum Strontium Copper Oxide (LSCO) was also tested as a normal metal overlayer because of its compatibility with the high deposition temperature for...fabricate YBCO/ISCO SEB junctions using a variety of step heights (110 nm - 330 nm) on Neodymium Gallate (NGO) substrates. NGO was chosen as a...substrate because of its excellent lattice match to YBCO and its lack of crystal twinning Twinning had been a drawback of Lanthanum Aluminate (LAO)- L

Off Axis Growth of Strontium Titanate Films with High Dielectric Constant Tuning and Low Loss

DTIC Science & Technology

2003-04-03

80309, U.S.A. ABSTRACT We have measured the nonlinear dielectric properties of strontium titanate (STO) thin films grown on neodymium gallate (NGO...and lanthanum aluminate (LAO) substrates. The films prepared by off-axis pulsed laser deposition were characterized by their dielectric constant and...performed on the films prepared with the off axis growth. EXPERIMENTAL Pulsed laser deposition (PLD) was used to deposit STO films on lanthanum

Implications of Competition for Rare Earth Elements (REE) in Africa

DTIC Science & Technology

2011-03-15

German’s began their North African campaign. They 3 wanted to reach the Saudi Arabian oilfields to keep their military juggernaut from grinding to a...industry is a fairly recent phenomenon as compared to other precious metals such as gold or copper, which has been known and valued for millenniums. The...and include: lanthanum, cerium, praseodymium, and neodymium, which are often found in heavy concentrations ranging from eighty to ninety percent of

RESEARCH ON PHYSICAL AND CHEMICAL PRINCIPLES AFFECTING HIGH TEMPERATURE MATERIALS FOR ROCKET NOZZLES. Quarterly Progress Report, April 1, 1963-June 30, 1963

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lowrie, R.

1963-10-31

The development and properties of refractory materials are described. Corrosion of zirconium carbide, niobium carbide, and niobium carbide-zirconium carbide systems by carbon dioxide and hydrochloric acid at 2250 deg C is reported. Corrosion of silver-tungsten alloys by carbon dioxide and oxygen at 2150 to 2440 deg K is summarized. Measurements of pyrolytic and ZTA graphite corrosion by carbon dioxide and oxygen at 2100 to 2800 deg K are shown. At 2300 deg C the rate of formation of methane from graphite and hydrogen is greatly reduced by the addition of helium, at constant hydrogen pressure. Up to 2000 deg Cmore » the effect of helium is small. The pyrolysis of methane on graphite at 2000 deg C is tabulated. Oxidation of tungsten to form WO/sub 2/ and WO/sub 3/ is reported. Vaporization of hafnium borides at 2297 to 2538 deg K is analyzed. The lattice parameters of ZrB/sub 2/ at of TiN/sub 0.6/ and TiN/sub 0.75/ are discussed. Powder metallurgical techniques are used to prepare TiB/sub 2/, ZrB/sub 2/, HfB/ sub 2/, NbB/sub 2/, a nd TaB/sub 2/ for detailed x-ray characterization. The electric conductivity of NbC-ZrC systems is reported. General descriptions are given of analytical techniques for free carbon in carbides and spectrographic methods for metallic impurities in carbides and borides. Preliminary roomtemperature measurements are reported of the elastic properties of polycrystalline ZrB/sub 2/. Titanium carbide is brazed to tungsten with a platinum-boron system. A largegrained polycrystalline specimen of ZrC is plastically deformed in creep at 2134 deg C. Metallographic and x-ray examinations of polycrystalline TiC specimens deformed in creep reveal an increasing development with deformation of subgrains having preferred orientation. (N.W.R.)« less

Tectonic setting and metallogenesis of volcanogenic massive sulfide deposits in the Bonnifield Mining District, Northern Alaska Range: Chapter B in Recent U.S. Geological Survey studies in the Tintina Gold Province, Alaska, United States, and Yukon, Canada--results of a 5-year project

USGS Publications Warehouse

Dusel-Bacon, Cynthia; Aleinikoff, John N.; Premo, Wayne R.; Paradis, Suzanne; Lohr-Schmidt, Ilana; Gough, Larry P.; Day, Warren C.

2007-01-01

This paper summarizes the results of field and laboratory investigations, including whole-rock geochemistry and radiogenic isotopes, of outcrop and drill core samples from volcanogenic massive sulfide (VMS) deposits and associated metaigneous rocks in the Wood River area of the Bonnifield mining district, northern Alaska Range (see fig. 1 of Editors’ Preface and Overview). U-Pb zircon igneous crystallization ages from felsic rocks indicate a prolonged period of Late Devonian to Early Mississippian (373±3 to 357±4 million years before present, or Ma) magmatism. This magmatism occurred in a basinal setting along the ancient Pacific margin of North America. The siliceous and carbonaceous compositions of metasedimentary rocks, Precambrian model ages based on U-Pb dating of zircon and neodymium ages, and for some units, radiogenic neodymium isotopic compositions and whole-rock trace-element ratios similar to those of continental crust are evidence for this setting. Red Mountain (also known as Dry Creek) and WTF, two of the largest VMS deposits, are hosted in peralkaline metarhyolite of the Mystic Creek Member of the Totatlanika Schist. The Mystic Creek Member is distinctive in having high concentrations of high-field-strength elements (HFSE) and rare-earth elements (REE), indicative of formation in a within-plate (extensional) setting. Mystic Creek metarhyolite is associated with alkalic, within-plate basalt of the Chute Creek Member; neodymium isotopic data indicate an enriched mantle component for both members of this bimodal (rhyolite-basalt) suite. Anderson Mountain, the other significant VMS deposit, is hosted by the Wood River assemblage. Metaigneous rocks in the Wood River assemblage span a wide compositional range, including andesitic rocks, which are characteristic of arc volcanism. Our data suggest that the Mystic Creek Member likely formed in an extensional, back-arc basin that was associated with an outboard continental-margin volcanic arc that included rocks of the Wood River assemblage. We suggest that elevated HFSE and REE trace-element contents of metavolcanic rocks, whose major-element composition may have been altered, are an important prospecting tool for rocks of VMS deposit potential in east-central Alaska.

Neodymium cobalt oxide as a chemical sensor

NASA Astrophysics Data System (ADS)

Abdel-Latif, I. A.; Rahman, Mohammed M.; Khan, Sher Bahadar

2018-03-01

Chemical sensing and electrical transport properties of neodymium coblate, NdCoO3, was investigated in this work. It was prepared by using co-precipitation method. Pure neodymium chloride and cobalt chloride were mixing in the presence of sodium hydroxide and the obtained co-precipitated powder was calcined at 850 and 1000 °C. The synthesized composites, as-grown (NdCoO3-I), calcined at 850 °C (NdCoO3-II), and calcined at 1000 °C (NdCoO3-III) were studied in details in terms of their morphological and structural properties. The X-ray analysis confirmed that the synthesized products are well crystalline possessing single phase orthorhombic crystal system of space group Pbnm(62). The crystallite size of NdCoO3-I, NdCoO3-II, and NdCoO3-III is 22, 111, and 338 nm, respectively which reflect that crystallite size is increasing with increase in firing temperature. The DC resistivity was measured as a function of temperature in the temperature range from room temperature up to 200 °C. All NdCoO3 are semiconductor in this range of temperature but showed different activation energy which strongly depends on the crystallite size of the products. The activation energy decreased with increase in crystallite size, 0.798, 0.414 and 0.371 eV for NdCoO3-I, NdCoO3-II, and NdCoO3-III, respectively. Thus resistivity increases with increase in crystallite size of NdCoO3. All NdCoO3 products were tested as chemical sensor for acetone by electrochemical approaches and showed excellent sensitivity. Among the NdCoO3 samples, NdCoO3-III showed the highest sensitivity (3.4722 μAcm-2 mM-1) compared to other compositions and gradually decreased to 3.2407 μAcm-2 mM-1 with decreasing the crystallite size of NdCoO3-II. It is also observed that the sensitivity drastically decreased to 0.76253 μAcm-2 mM-1 in the case of NdCoO3-I. It is introduced an efficient route for the detection of environmental unsafe chemicals by electrochemical approach for the safety of healthcare and environmental fields in broad scales.

The effect of anti-phase domain size on the ductility of a rapidly solidified Ni3Al-Cr alloy

NASA Technical Reports Server (NTRS)

Carro, G.; Bertero, G. A.; Wittig, J. E.; Flanagan, W. F.

1989-01-01

Tensile tests on splat-quenched Ni3Al-Cr alloys showed a sharp decrease in ductility with long-time annealing. The growth of the initially very-fine-size anti-phase domains showed a tenuous correlation with ductility up to a critical size, where ductility was lost. The grain size was relatively unaffected by these annealing treatments, but the grain-boundary curvature decreased, implying less toughness. An important observation was that, for the longest annealing time, a chromium-rich precipitate formed, which the data indicate could be a boride. Miniaturized tensile tests were performed on samples which were all obtained from the same splat-quenched foil, and the various domain sizes were controlled by subsequent annealing treatments.

Two phase titanium aluminide alloy

DOEpatents

Deevi, Seetharama C.; Liu, C. T.

2001-01-01

A two-phase titanic aluminide alloy having a lamellar microstructure with little intercolony structures. The alloy can include fine particles such as boride particles at colony boundaries and/or grain boundary equiaxed structures. The alloy can include alloying additions such as .ltoreq.10 at % W, Nb and/or Mo. The alloy can be free of Cr, V, Mn, Cu and/or Ni and can include, in atomic %, 45 to 55% Ti, 40 to 50% Al, 1 to 5% Nb, 0.3 to 2% W, up to 1% Mo and 0.1 to 0.3% B. In weight %, the alloy can include 57 to 60% Ti, 30 to 32% Al, 4 to 9% Nb, up to 2% Mo, 2 to 8% W and 0.02 to 0.08% B.

Combustion synthesis of boride and other composites

DOEpatents

Halverson, Danny C.; Lum, Beverly Y.; Munir, Zuhair A.

1989-01-01

A self-sustaining combustion synthesis process for producing hard, tough, lightweight B.sub.4 C/TiB.sub.2 composites is based on the thermodynamic dependence of adiabatic temperature and product composition on the stoichiometry of the B.sub.4 C and TiB.sub.2 reactants. For lightweight products the composition must be relatively rich in the B.sub.4 C component. B.sub.4 C-rich composites are obtained by varying the initial temperature of the reactants. The product is hard, porous material whose toughness can be enhanced by filling the pores with aluminum or other metal phases using a liquid metal infiltration process. The process can be extended to the formation of other composites having a low exothermic component.

Oxidation-induced contraction and strengthening of boron fibers

NASA Technical Reports Server (NTRS)

Dicarlo, J. A.; Wagner, T. C.

1981-01-01

An investigation was conducted to measure and understand the physical and mechanical effects that occur in boron fibers during and after thermal treatment in a controlled oxygen argon gaseous mixture. Of principal concern was the optimization of this treatment as a secondary processing method for significantly improving fiber tensile strength. Strengthening was accomplished by an oxidation induced axial contraction of the fiber and a resulting axial compression of strength limiting flaws within the fiber's tungsten boride core. Various physical observations were used to develop mechanistic models for oxidation, contraction, and flow formation. Processing guidelines are discussed for possibly exceeding the 5.5 GN/sq m strength limit and also for achieving fiber strengthening during application of boron containing diffusion barrier coatings.

Characterization and Computational Modeling of Minor Phases in Alloy LSHR

NASA Technical Reports Server (NTRS)

Jou, Herng-Jeng; Olson, Gregory; Gabb, Timothy; Garg, Anita; Miller, Derek

2012-01-01

The minor phases of powder metallurgy disk superalloy LSHR were studied. Samples were consistently heat treated at three different temperatures for long times to approach equilibrium. Additional heat treatments were also performed for shorter times, to assess minor phase kinetics in non-equilibrium conditions. Minor phases including MC carbides, M23C6 carbides, M3B2 borides, and sigma were identified. Their average sizes and total area fractions were determined. CALPHAD thermodynamics databases and PrecipiCalc(TradeMark), a computational precipitation modeling tool, were employed with Ni-base thermodynamics and diffusion databases to model and simulate the phase microstructural evolution observed in the experiments with an objective to identify the model limitations and the directions of model enhancement.

Long-term remission of folliculitis decalvans after treatment with the long-pulsed Nd:YAG laser.

PubMed

Meesters, Arne A; Van der Veen, J P Wietze; Wolkerstorfer, Albert

2014-04-01

Folliculitis decalvans (FD) is a rare inflammatory scalp disorder presenting with tufted folliculitis, follicular papules and pustules, progressing to cicatricial alopecia. Current treatments mainly consist of antibiotic and immunomodulatory therapies and are often disappointing. FD has previously shown to respond to treatment with neodymium:yttrium aluminium garnet (Nd:YAG) laser in one case. We present a case of recalcitrant FD, successfully treated with a long-pulsed Nd:YAG laser.

Rare Earth Element Concentrations from Wells at the Don A. Campbell Geothermal Plant, Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fowler, Andrew; Zierenberg, Robert

* Requires permission of originators for use. Rare earth element concentrations in thermal springs from the wells at the Don A. Campbell geothermal plant, Nevada. Samples taken from geothermal wells 85-11, 65-11, 54-11, and 64-11. Includes pH and concentrations for Cerium, Dysprosium, Erbium, Europium, Gadolinium, Holmium, Lanthanum, Lutetium, Neodymium, Praseodymium, Samarium, Terbium, Thulium, Yttrium, and Ytterbium. Samples from Don A. Campbell, Nevada collected on October 14, 2016.

Experimental establishment of the erosion nature of the pulsed low-threshold optical breakdown of air near the surface

NASA Astrophysics Data System (ADS)

Min'ko, L. Ia.; Chumakov, A. N.; Chivel', Iu. A.

1988-08-01

Nanosecond kinetic spectroscopy methods are used to establish the erosion nature of the pulsed low-threshold optical breakdown of air near the surface upon exposure of certain metals (indium, lead) to microsecond neodymium and CO2 laser radiation. It is shown that this optical breakdown of air by CO2 laser radiation is accompanied by the formation of a plasma spectrum which is optically thin in the visible range.

DBR and DFB Lasers in Neodymium- and Ytterbium-Doped Photothermorefractive Glasses

NASA Technical Reports Server (NTRS)

Ryasnyanskiy, Aleksandr; Vorobiev, N.; Smirnov, V.; Lumeau, J.; Glebov, A.; Mokhun, O..; Spiegelberg, Ch.; Krainak, Michael A.; Glebov, A.; Glebov, L.

2014-01-01

The first demonstration, to the best of our knowledge, of distributed Bragg reflector (DBR) and monolithic distributed feedback (DFB) lasers in photothermorefractive glass doped with rare-earth ions is reported. The lasers were produced by incorporation of the volume Bragg gratings into the laser gain elements. A monolithic single-frequency solid-state laser with a line width of 250 kHz and output power of 150 mW at 1066 nm is demonstrated.

Implications of convection in the Moon and the terrestrial planets

NASA Technical Reports Server (NTRS)

Turcotte, Donald L.

1987-01-01

The early thermal and chemical evolution of the Moon is discussed. The rubidium-strontium, neodymium-samarium, and uranium-thorium-lead systems were studied. The relation of source region heterogeneity to the mixing associated with mantle convection is considered. Work on the application of fractal concepts to planetary geology and geophysics is also discussed. The fractal concept was applied to fragmentation, including the frequency-size distribution of meteorites, asteroids and particulate matter produced by impacts.

Models of earth structure inferred from neodymium and strontium isotopic abundances

PubMed Central

Wasserburg, G. J.; DePaolo, D. J.

1979-01-01

A simplified model of earth structure based on the Nd and Sr isotopic characteristics of oceanic and continental tholeiitic flood basalts is presented, taking into account the motion of crustal plates and a chemical balance for trace elements. The resulting structure that is inferred consists of a lower mantle that is still essentially undifferentiated, overlain by an upper mantle that is the residue of the original source from which the continents were derived. PMID:16592688

Bibliography of Soviet Laser Developments, Number 49, September-October 1980

DTIC Science & Technology

1981-10-01

Shcherbakov ( 1 ). Synthesis and study of spectral-luminescent and lasing properties of aluminum borate crystals doped with chromium and neodymium. KE, no. 10...A ’IDST-2700Z4004- 1 LEVEt~ I i DEFENSEINTELLIGENCE / 7O AGENCY Bibliography of Soviet Laser Developments (U) September- October 1980 OCTOBER INI...DOCUMENTATION PAGE READ ISTRPUCTONSBEFORE COMPLETING FORM 1 . REPOR NUMN 2. GOVT ACCES SION O. L. RECIPIENT’S CATALOG NUM BER DST-2700Z-004-81 - ’.,) ___ _ _ 4

Bibliography of Soviet Laser Developments, Number 66, July-August 1983.

DTIC Science & Technology

1984-09-01

7 5. Glass : Nd............................................8 6. Glass : Er............................................9 7. Glass ...upper lasing level of neodymium in y-La2S 3 semiconductor crystals and _a2S_ 2Ga20 3 glass . KE, no. 8, 1983, 1560-1564. 7. Kaminskiy, A.A., N.R. Agamalyan...injection semiconductor lasers. FTP, no. 7, 1983, 1353-1355. 5. Glass : Nd 44. Gvatua, Sh.Sh., Z.V. Katselashvili, V.N. Polukhin, S.N. Popov, T.V. Prangishvili

Bibliography of Soviet Laser Developments, Number 67, September-October 1983.

DTIC Science & Technology

1984-12-05

5 g. Pb(l-x)Sn(x)Te .................. 5 iv V.--",7 4. Glass a. Mdscellaneous.................... 6- c., Er...the threshold current in injection lasers based on Pbl-xSnxTe semiconductors. FTPPA, no. 9v 1983, 1631-1634. 4. Glass a. Miscellaneous b. Nd 45...Shcherbakov, A.A.; Mak, A.A.; Sklizkov, G.V. (FIAN). Limit efficiency of neodymium glass lasers. KRSFA, no. 9, 1983, 8-12. c . Er 46. Lunter, S.G.; Murzin

Investigation of Refractive Index Profile Induced with Femtosecond Pulses into Neodymium Doped Phosphate Glass for the Purposes of Hybrid Waveguiding Structures Formation

NASA Astrophysics Data System (ADS)

Bukharin, M.; Khudakov, D.; Vartapetov, S.

The technique of writing depressed cladding waveguides into Nd:phosphate glass with relatively large mode field diameter in 2-line geometry was reported for the purposes of waveguiding structures formation. The easy to use and accurate technique of induced refractive index measurement was proposed, and it was shown the inefficiency of widespread indirect (numerical aperture) technique of refractive index measurement for such femtosecond written waveguides.