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.

Dosimetric properties of dysprosium doped lithium borate glass irradiated by 6 MV photons

NASA Astrophysics Data System (ADS)

Ab Rasid, A.; Wagiran, H.; Hashim, S.; Ibrahim, Z.; Ali, H.

2015-07-01

Undoped and dysprosium doped lithium borate glass system with empirical formula (70-x) B2O3-30 Li2O-(x) Dy2O3 (x=0.1, 0.3, 0.5, 0.7, 1.0 mol%) were prepared using the melt-quenching technique. The dosimetric measurements were performed by irradiating the samples to 6 MV photon beam using linear accelerator (LINAC) over a dose range of 0.5-5.0 Gy. The glass series of dysprosium doped lithium borate glass produced the best thermoluminescence (TL) glow curve with the highest intensity peak from sample with 1.0 mol% Dy2O3 concentration. Minimum detectable dose was detected at 2.24 mGy, good linearity of regression coefficient, high reproducibility and high sensitivity compared to the undoped glass are from 1.0 mol% dysprosium doped lithium borate glass. The results indicated that the series of dysprosium doped lithium glasses have a great potential to be considered as a thermoluminescence dosimetry (TLD).

Critical Rare Earths, National Security, and U.S.-China Interactions: A Portfolio Approach to Dysprosium Policy Design

DTIC Science & Technology

2015-01-01

by the graduate fellow’s faculty committee. C O R P O R A T I O N Dissertation Critical Rare Earths, National Security, and U.S.-China Interactions A...Portfolio Approach to Dysprosium Policy Design David L. An Dissertation Critical Rare Earths, National Security, and U.S.-China Interactions A...Permanent Magnet ................................................ xxiv Dysprosium, the Most Critical Rare Earth

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.

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

Jaques, Brian; Butt, Darryl P.; Marx, Brian M.

A carbothermic reduction of the metal oxides in a hydrogen/nitrogen mixed gas stream prior to nitriding in a nitrogen gas stream was used to synthesize uranium nitride at 1500 deg. C, cerium nitride at 1400 deg. C, and dysprosium nitride at 1500 deg. C. Cerium nitride and dysprosium nitride were also synthesized via hydriding and nitriding the metal shavings at 900 deg. C and 1500 deg. C, respectively. Also, a novel ball-milling synthesis route was used to produce cerium nitride and dysprosium nitride from the metal shavings at room temperature. Dysprosium nitride was also produced by reacting the metal shavingsmore » in a high purity nitrogen gas stream at 1300 deg. C. All materials were characterized by phase analysis via X-ray diffraction. Only the high purity materials were further analyzed via chemical analysis to characterize the trace oxygen concentration. (authors)« less

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

An electrostatic model for the determination of magnetic anisotropy in dysprosium complexes.

PubMed

Chilton, Nicholas F; Collison, David; McInnes, Eric J L; Winpenny, Richard E P; Soncini, Alessandro

2013-01-01

Understanding the anisotropic electronic structure of lanthanide complexes is important in areas as diverse as magnetic resonance imaging, luminescent cell labelling and quantum computing. Here we present an intuitive strategy based on a simple electrostatic method, capable of predicting the magnetic anisotropy of dysprosium(III) complexes, even in low symmetry. The strategy relies only on knowing the X-ray structure of the complex and the well-established observation that, in the absence of high symmetry, the ground state of dysprosium(III) is a doublet quantized along the anisotropy axis with an angular momentum quantum number mJ=±(15)/2. The magnetic anisotropy axis of 14 low-symmetry monometallic dysprosium(III) complexes computed via high-level ab initio calculations are very well reproduced by our electrostatic model. Furthermore, we show that the magnetic anisotropy is equally well predicted in a selection of low-symmetry polymetallic complexes.

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

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.

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.

Mixed (phthalocyaninato)(Schiff-base) di-dysprosium sandwich complexes. Effect of magnetic coupling on the SMM behavior.

PubMed

Wang, Hailong; Liu, Chenxi; Liu, Tao; Zeng, Suyuan; Cao, Wei; Ma, Qi; Duan, Chunying; Dou, Jianmin; Jiang, Jianzhuang

2013-11-21

Reaction between Schiff-base ligand and half-sandwich complex M(Pc)(acac) led to the isolation of new sandwich-type mixed (phthalocyaninato)(Schiff-base) di-lanthanide compounds M2(Pc)2(L)H2O (M = Dy, Gd) (1, 2) [H2Pc = metal free phthalocyanine, Hacac = acetylacetone, H2L = N,N'-bis(3-methyloxysalicylidene)benzene-1,2-diamine] with the triple-decker molecular structure clearly revealed by single crystal X-ray diffraction analysis. For the comparative studies, sandwich triple-decker analogues with pure Schiff-base ligand M2(L)3H2O (M = Dy, Gd) (3, 4) were also prepared. Dynamic magnetic measurement result reveals the single-molecule magnet (SMM) nature of the di-dysprosium derivative 1, while the static magnetic investigation over both pure and the diamagnetic diluted samples of this compound discloses the interionic ferromagnetic coupling between the two dysprosium ions, which in turn effectively suppresses the QTM and enhances the energy barrier of this SMM. Nevertheless, comparative studies over the static magnetic properties of the di-dysprosium triple-decker complexes 1 and 3 indicate the stronger magnetic coupling between the two lanthanide ions in mixed (phthalocyaninato)(Schiff-base) species than in the pure Schiff-base triple-decker analogue, suggesting the special coordination sphere around the dysprosium ions in the former compound over the latter one on the more intense inter-ionic ferromagnetic coupling. As a very small step towards understanding the structure-property relationship, the present result will be surely helpful for the design and synthesis of the multinuclear lanthanide-based SMMs with good properties.

Semiconductor composition containing iron, dysprosium, and terbium

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

Pooser, Raphael C.; Lawrie, Benjamin J.; Baddorf, Arthur P.

An amorphous semiconductor composition includes 1 to 70 atomic percent iron, 15 to 65 atomic percent dysprosium, 15 to 35 atomic percent terbium, balance X, wherein X is at least one of an oxidizing element and a reducing element. The composition has an essentially amorphous microstructure, an optical transmittance of at least 50% in at least the visible spectrum and semiconductor electrical properties.

In vitro and in vivo dissolution behavior of a dysprosium lithium borate glass designed for the radiation synovectomy treatment of rheumatoid arthritis.

PubMed

Conzone, Samuel D; Brown, Roger F; Day, Delbert E; Ehrhardt, Gary J

2002-05-01

Dysprosium lithium borate (DyLB) glass microspheres were investigated for use in the radiation synovectomy treatment of rheumatoid arthritis. In vitro testing focused on weight loss and cation dissolution from glass microspheres immersed in simulated synovial fluid (SSF) at 37 degrees C for up to 64 days. In vivo testing was performed by injecting glass microspheres into the stifle joints of Sprague-Dawley rats and monitoring the biodegradability of the microspheres and the tissue response within the joints. The DyLB microspheres reacted nonuniformly in SSF with the majority of lithium and boron being dissolved, whereas nearly all of the dysprosium (>99.7%) remained in the reacted microspheres. Because the DyLB glasses released negligible amounts of dysprosium while reacting with SSF, they are considered safe for radiation synovectomy from the standpoint of unwanted radiation release from the joint capsule. Furthermore, the DyLB microspheres fragmented, degraded, and reacted with body fluids while in the joints of rats without histologic evidence of joint damage. Copyright 2002 Wiley Periodicals, Inc. J Biomed Mater Res 60: 260--268, 2002; DOI 10.1002/jbm.10047

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.

40 CFR 721.9511 - Silicic acid (H6SiO2O7), magnesium, strontium salt(1:1:2), dysprosium and europium-doped.

Code of Federal Regulations, 2010 CFR

2010-07-01

... ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9511 Silicic acid (H6SiO2O7), magnesium, strontium salt(1:1:2), dysprosium and europium-doped. (a) Chemical substance and significant new...

Sandwich-type tetrakis(phthalocyaninato) dysprosium-cadmium quadruple-decker SMM.

PubMed

Wang, Hailong; Qian, Kang; Wang, Kang; Bian, Yongzhong; Jiang, Jianzhuang; Gao, Song

2011-09-14

Homoleptic tetrakis[2,3,9,10,16,17,23,24-octa(butyloxy)phthalocyaninato] dysprosium-cadmium quadruple-decker complex 1 was isolated in relatively good yield of 43% from a simple one-pot reaction. This compound represents the first sandwich-type tetrakis(phthalocyaninato) rare earth-cadmium quadruple-decker SMM that has been structurally characterized. This journal is © The Royal Society of Chemistry 2011

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.

Peripheral Substitution: An Easy Way to Tuning the Magnetic Behavior of Tetrakis(phthalocyaninato) Dysprosium(III) SMMs

PubMed Central

Shang, Hong; Zeng, Suyuan; Wang, Hailong; Dou, Jianmin; Jiang, Jianzhuang

2015-01-01

Two tetrakis(phthalocyaninato) dysprosium(III)-cadmium(II) single-molecule magnets (SMMs) with different extent of phthalocyanine peripheral substitution and therefore different coordination geometry for the Dy ions were revealed to exhibit different SMM behavior, providing an easy way to tuning and controlling the molecular structure and in turn the magnetic properties of tetrakis(tetrapyrrole) lanthanide SMMs through simple tetrapyrrole peripheral substitution. PMID:25744587

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.

{Delta}I = 2 energy staggering in normal deformed dysprosium nuclei

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

Riley, M.A.; Brown, T.B.; Archer, D.E.

1996-12-31

Very high spin states (I{ge}50{Dirac_h}) have been observed in {sup 155,156,157}Dy. The long regular band sequences, free from sharp backbending effects, observed in these dysprosium nuclei offer the possibility of investigating the occurence of any {Delta}I = 2 staggering in normal deformed nuclei. Employing the same analysis techniques as used in superdeformed nuclei, certain bands do indeed demonstrate an apparent staggering and this is discussed.

40 CFR 721.9511 - Silicic acid (H6SiO2O7), magnesium, strontium salt(1:1:2), dysprosium and europium-doped.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Silicic acid (H6SiO2O7), magnesium...), magnesium, strontium salt(1:1:2), dysprosium and europium-doped. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as silicic acid (H6SiO2O7) magnesium...

40 CFR 721.9511 - Silicic acid (H6SiO2O7), magnesium, strontium salt(1:1:2), dysprosium and europium-doped.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Silicic acid (H6SiO2O7), magnesium...), magnesium, strontium salt(1:1:2), dysprosium and europium-doped. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as silicic acid (H6SiO2O7) magnesium...

40 CFR 721.9511 - Silicic acid (H6SiO2O7), magnesium, strontium salt(1:1:2), dysprosium and europium-doped.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Silicic acid (H6SiO2O7), magnesium...), magnesium, strontium salt(1:1:2), dysprosium and europium-doped. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as silicic acid (H6SiO2O7) magnesium...

40 CFR 721.9511 - Silicic acid (H6SiO2O7), magnesium, strontium salt(1:1:2), dysprosium and europium-doped.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Silicic acid (H6SiO2O7), magnesium...), magnesium, strontium salt(1:1:2), dysprosium and europium-doped. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as silicic acid (H6SiO2O7) magnesium...

Technique for direct measurement of magnetic entropy of solids: Results for dysprosium titanium oxide

NASA Technical Reports Server (NTRS)

Flood, D. J.

1974-01-01

A measurement technique was devised which permits direct observation of the magnetic entropy of solids as a function of applied magnetic field. Measurements were made of the magnetic entropy, in the temperature range 2 to 20 K, of polycrystalline samples of dysprosium titanium oxide (Dy2Ti2O7) to determine its suitability for use as the working substance of a magnetic refrigerator. Magnetization measurements were also made at 4.2 K and below to provide additional information on the nature of the compound. The measurements indicated that crystalline electric fields perturbed the ground state of the dysprosium ions, removed the 16-fold degeneracy predicted by Hund's rules, and left only a twofold degeneracy in its place. A positive, temperature independent contribution to the magnetization was observed in the saturation region, which indicated that the doublet ground-state wave function was perturbed by a nearby unpopulated upper energy level.

Cermet electrode

DOEpatents

Maskalick, Nicholas J.

1988-08-30

Disclosed is a cermet electrode consisting of metal particles of nickel, cobalt, iron, or alloys or mixtures thereof immobilized by zirconia stabilized in cubic form which contains discrete deposits of about 0.1 to about 5% by weight of praseodymium, dysprosium, terbium, or a mixture thereof. The solid oxide electrode can be made by covering a substrate with particles of nickel, cobalt, iron, or mixtures thereof, growing a stabilized zirconia solid oxide skeleton around the particles thereby immobilizing them, contacting the skeleton with a compound of praseodymium, dysprosium, terbium, or a mixture thereof, and heating the skeleton to a temperature of at least 500.degree. C. The electrode can also be made by preparing a slurry of nickel, cobalt, iron, or mixture and a compound of praseodymium, dysprosium, terbium, or a mixture thereof, depositing the slurry on a substrate, heating the slurry to dryness, and growing a stabilized zirconia skeleton around the metal particles.

Relaxation dynamics of dysprosium(III) single molecule magnets.

PubMed

Guo, Yun-Nan; Xu, Gong-Feng; Guo, Yang; Tang, Jinkui

2011-10-21

Over the past decade, lanthanide compounds have become of increasing interest in the field of Single Molecule Magnets (SMMs) due to the large inherent anisotropy of the metal ions. Heavy lanthanide metal systems, in particular those containing the dysprosium(III) ion, have been extensively employed to direct the formation of a series of SMMs. Although remarkable progress is being made regarding the synthesis and characterization of lanthanide-based SMMs, the understanding and control of the relaxation dynamics of strongly anisotropic systems represents a formidable challenge, since the dynamic behaviour of lanthanide-based SMMs is significantly more complex than that of transition metal systems. This perspective paper describes illustrative examples of pure dysprosium(III)-based SMMs, published during the past three years, showing new and fascinating phenomena in terms of magnetic relaxation, aiming at shedding light on the features relevant to modulating relaxation dynamics of polynuclear lanthanide SMMs. This journal is © The Royal Society of Chemistry 2011

Selective recognition of dysprosium(III) ions by enhanced chemiluminescence CdSe quantum dots

NASA Astrophysics Data System (ADS)

Hosseini, Morteza; Ganjali, Mohammad R.; Vaezi, Zahra; Faridbod, Farnoush; Arabsorkhi, Batool; Sheikhha, Mohammad H.

2014-03-01

The intensity of emitted light from CdSe quantum dots (QDs)-H2O2 is described as a novel chemiluminescence (CL) reaction for determination of dysprosium. This reaction is based on the catalytic effect of Dy3+ ions, causing a significant increase in the light emission, as a result of the reaction of quantum dots (QDs) with hydrogen peroxide. In the optimum conditions, this method was satisfactorily described by linear calibration curve in the range of 8.3 × 10-7-5.0 × 10-6 M, the detection limit of 6.0 × 10-8 M, and the relative standard deviation for five determinations of 2.5 × 10-6 M Dy3+ 3.2%. The main experimental advantage of the proposed method is its selective to Dy3+ ions compared with common coexisting cations, therefore, it was successfully applied for the determination of dysprosium ions in water samples.

Emission beyond 4  μm and mid-infrared lasing in a dysprosium-doped indium fluoride (InF3) fiber.

PubMed

Majewski, Matthew R; Woodward, Robert I; Carreé, Jean-Yves; Poulain, Samuel; Poulain, Marcel; Jackson, Stuart D

2018-04-15

Optical emission from rare-earth-doped fluoride fibers has thus far been limited to less than 4 μm. We extend emission beyond this limit by employing an indium fluoride (InF 3 ) glass fiber as the host, which exhibits an increased infrared transparency over commonly used zirconium fluoride (ZBLAN). Near-infrared pumping of a dysprosium-doped InF 3 fiber results in broad emission centered around 4.3 μm, representing the longest emission yet achieved from a fluoride fiber. The first laser emission in an InF 3 fiber is also demonstrated from the 3 μm dysprosium transition. Finally, a frequency domain excited state lifetime measurement comparison between fluoride hosts suggests that multiphonon effects are significantly reduced in indium fluoride fiber, paving the way to more efficient, longer wavelength lasers compared to ZBLAN fibers.

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

Glass microspheres for medical applications

NASA Astrophysics Data System (ADS)

Conzone, Samuel David

Radioactive dysprosium lithium borate glass microspheres have been developed as biodegradable radiation delivery vehicles for the radiation synovectomy treatment of rheumatoid arthritis. Once injected into a diseased joint, the microspheres deliver a potent dose of radiation to the diseased tissue, while a non-uniform chemical reaction converts the glass into an amorphous, porous, hydrated dysprosium phosphate reaction product. The non-radioactive, lithium-borate component is dissolved from the glass (up to 94% weight loss), while the radioactive 165Dy reacts with phosphate anions in the body fluids, and becomes "chemically" trapped in a solid, dysprosium phosphate reaction product that has the same size as the un-reacted glass microsphere. Ethylene diamine tetraacetate (EDTA) chelation therapy can be used to dissolve the dysprosium phosphate reaction product after the radiation delivery has subsided. The dysprosium phosphate reaction product, which formed in vivo in the joint of a Sprague-Dawley rat, was dissolved by EDTA chelation therapy in <1 week, without causing any detectable joint damage. The combination of dysprosium lithium borate glass microspheres and EDTA chelation therapy provides an unique "tool" for the medical community, which can deliver a large dose (>100 Gy) of localized beta radiation to a treatment site within the body, followed by complete biodegradability. The non-uniform reaction process is a desirable characteristic for a biodegradable radiation delivery vehicle, but it is also a novel material synthesis technique that can convert a glass to a highly porous materials with widely varying chemical composition by simple, low-temperature, glass/solution reaction. The reaction product formed by nonuniform reaction occupies the same volume as the un-reacted glass, and after drying for 1 h at 300°C, has a specific surface area of ≈200 m2/g, a pore size of ≈30 nm, and a nominal crushing strength of ≈10 MPa. Finally, rhenium glass microspheres, composed of micron-sized, metallic rhenium particles dispersed within a magnesium alumino borate glass matrix were produced by sintering ReO2 powder and glass frit at 1050°C. A 50 mg injection of radioactive rhenium glass microspheres containing 3.7 GBq of 186Re and 8.5 GBq of 188Re could be used to deliver a 100 Gy dose to a cancerous tumor, while limiting the total body dose caused by rhenium dissolution to approximately 1 mGy.

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.

Scanning Electron Microscope-Cathodoluminescence Analysis of Rare-Earth Elements in Magnets.

PubMed

Imashuku, Susumu; Wagatsuma, Kazuaki; Kawai, Jun

2016-02-01

Scanning electron microscope-cathodoluminescence (SEM-CL) analysis was performed for neodymium-iron-boron (NdFeB) and samarium-cobalt (Sm-Co) magnets to analyze the rare-earth elements present in the magnets. We examined the advantages of SEM-CL analysis over conventional analytical methods such as SEM-energy-dispersive X-ray (EDX) spectroscopy and SEM-wavelength-dispersive X-ray (WDX) spectroscopy for elemental analysis of rare-earth elements in NdFeB magnets. Luminescence spectra of chloride compounds of elements in the magnets were measured by the SEM-CL method. Chloride compounds were obtained by the dropwise addition of hydrochloric acid on the magnets followed by drying in vacuum. Neodymium, praseodymium, terbium, and dysprosium were separately detected in the NdFeB magnets, and samarium was detected in the Sm-Co magnet by the SEM-CL method. In contrast, it was difficult to distinguish terbium and dysprosium in the NdFeB magnet with a dysprosium concentration of 1.05 wt% by conventional SEM-EDX analysis. Terbium with a concentration of 0.02 wt% in an NdFeB magnet was detected by SEM-CL analysis, but not by conventional SEM-WDX analysis. SEM-CL analysis is advantageous over conventional SEM-EDX and SEM-WDX analyses for detecting trace rare-earth elements in NdFeB magnets, particularly dysprosium and terbium.

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.

Making two dysprosium atoms rotate —Einstein-de Haas effect revisited

NASA Astrophysics Data System (ADS)

Górecki, Wojciech; Rzążewski, Kazimierz

2016-10-01

We present a numerical study of the behaviour of two magnetic dipolar atoms trapped in a harmonic potential and exhibiting the standard Einstein-de Haas effect while subject to a time-dependent homogeneous magnetic field. Using a simplified description of the short-range interaction and the full expression for the dipole-dipole forces we show that under experimentally realisable conditions two dysprosium atoms may be pumped to a high (l > 20) value of the relative orbital angular momentum.

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.

X-ray laser

DOEpatents

Nilsen, Joseph

1991-01-01

An X-ray laser (10) that lases between the K edges of carbon and oxygen, i.e. between 44 and 23 Angstroms, is provided. The laser comprises a silicon (12) and dysprosium (14) foil combination (16) that is driven by two beams (18, 20) of intense line focused (22, 24) optical laser radiation. Ground state nickel-like dysprosium ions (34) are resonantly photo-pumped to their upper X-ray laser state by line emission from hydrogen-like silicon ions (32). The novel X-ray laser should prove especially useful for the microscopy of biological specimens.

The effects of the porous buffer layer and doping with dysprosium on internal stresses in the GaInP:Dy/por-GaAs/GaAs(100) heterostructures

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

Seredin, P. V.; Gordienko, N. N.; Glotov, A. V.

2009-08-15

In structures with a porous buffer layer, residual internal stresses caused by a mismatch between the crystal-lattice parameters of the epitaxial GaInP alloy and the GaAs substrate are redistributed to the porous layer that acts as a buffer and is conducive to disappearance of internal stresses. Doping of the epitaxial layer with dysprosium exerts a similar effect on the internal stresses in the film-substrate structure.

Custom Coordination Environments for Lanthanoids: Tripodal Ligands Achieve Near-Perfect Octahedral Coordination for Two Dysprosium-Based Molecular Nanomagnets.

PubMed

Lim, Kwang Soo; Baldoví, José J; Jiang, ShangDa; Koo, Bong Ho; Kang, Dong Won; Lee, Woo Ram; Koh, Eui Kwan; Gaita-Ariño, Alejandro; Coronado, Eugenio; Slota, Michael; Bogani, Lapo; Hong, Chang Seop

2017-05-01

Controlling the coordination sphere of lanthanoid complexes is a challenging critical step toward controlling their relaxation properties. Here we present the synthesis of hexacoordinated dysprosium single-molecule magnets, where tripodal ligands achieve a near-perfect octahedral coordination. We perform a complete experimental and theoretical investigation of their magnetic properties, including a full single-crystal magnetic anisotropy analysis. The combination of electrostatic and crystal-field computational tools (SIMPRE and CONDON codes) allows us to explain the static behavior of these systems in detail.

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

Dysprosium electrodeposition from a hexaalkylguanidinium-based ionic liquid.

PubMed

Berger, Claudia A; Arkhipova, Maria; Maas, Gerhard; Jacob, Timo

2016-08-07

The rare-earth element dysprosium (Dy) is an important additive that increases the magnetocrystalline anisotropy of neodymium magnets and additionally prevents from demagnetizing at high temperatures. Therefore, it is one of the most important elements for high-tech industries and is mainly used in permanent magnetic applications, for example in electric vehicles, industrial motors and direct-drive wind turbines. In an effort to develop a more efficient electrochemical technique for depositing Dy on Nd-magnets in contrast to commonly used costly physical vapor deposition, we investigated the electrochemical behavior of dysprosium(iii) trifluoromethanesulfonate in a custom-made guanidinium-based room-temperature ionic liquid (RTIL). We first examined the electrodeposition of Dy on an Au(111) model electrode. The investigation was carried out by means of cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS). The initial stages of metal deposition were followed by in situ scanning tunneling microscopy (STM). CV measurements revealed a large cathodic reduction peak, which corresponds to the growth of monoatomic high islands, based on STM images taken during the initial stages of deposition. XPS identified these deposited islands as dysprosium. A similar reduction peak was also observed on an Nd-Fe-B substrate, and positively identified as deposited Dy using XPS. Finally, we varied the concentration of the Dy precursor, electrolyte flow and temperature during Dy deposition and demonstrated that each of these parameters could be used to increase the thickness of the Dy deposit, suggesting that these parameters could be tuned simultaneously in a temperature-controlled flow cell to enhance the thickness of the Dy layer.

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

Thermoluminescence glow curve deconvolution and trapping parameters determination of dysprosium doped magnesium borate glass

NASA Astrophysics Data System (ADS)

Salama, E.; Soliman, H. A.

2018-07-01

In this paper, thermoluminescence glow curves of gamma irradiated magnesium borate glass doped with dysprosium were studied. The number of interfering peaks and in turn the number of electron trap levels are determined using the Repeated Initial Rise (RIR) method. At different heating rates (β), the glow curves were deconvoluted into two interfering peaks based on the results of RIR method. Kinetic parameters such as trap depth, kinetic order (b) and frequency factor (s) for each electron trap level is determined using the Peak Shape (PS) method. The obtained results indicated that, the magnesium borate glass doped with dysprosium has two electron trap levels with the average depth energies of 0.63 and 0.79 eV respectively. These two traps have second order kinetic and are formed at low temperature region. The obtained results due to the glow curve analysis could be used to explain some observed properties such as, high thermal fading and light sensitivity for such thermoluminescence material. In this work, systematic procedures to determine the kinetic parameters of any thermoluminescence material are successfully introduced.

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.

Structure of dysprosium(111) dl-tartrate dimer in aqueous solution

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

Chevela, V.V.; Vulfson, S.G.; Salnikov, Y.I.

1994-10-01

The paramagnetic birefringence method was supplemented by numerical simulation to determine the molar paramagnetic-birefringence constant of the dysprosium dl-tartrate dimer Dy{sub 2}(d-L)(l-L){sup 2-} (I), where d-L{sup 4-} and l-L{sup 4-} are the deprotonated d- and l-tartaric acid molecules, respectively. The structure of the ligand and hydration surroundings of I was modeled by molecular mechanic calculations (the Dashevskii-Pylamovatyi model). It is shown that adequate results can be obtained only if one takes into account the coordination of I to the Na{sup +} ion.

Poly[[[μ3-N′-(carboxymethyl)ethylene­di­amine-N,N,N′-triacetato]dysprosium(III)] trihydrate

PubMed Central

Zhuang, Xiaomei; Long, Qingping; Wang, Jun

2010-01-01

In the title coordination polymer, {[Dy(C10H13N2O8)]·3H2O}n, the dysprosium(III) ion is coordinated by two N atoms and six O atoms from three different (carb­oxy­meth­yl)ethyl­ene­diamine­triacetate ligands in a distorted square-anti­prismatic geometry. The ligands connect the metal atoms, forming layers parallel to the ab plane. O—H⋯O hydrogen bonds further assemble adjacent layers into a three-dimensional supra­molecular network. PMID:21588859

Optical amplifier operating at 1.3 microns useful for telecommunications and based on dysprosium-doped metal chloride host materials

DOEpatents

Page, R.H.; Schaffers, K.I.; Payne, S.A.; Krupke, W.F.; Beach, R.J.

1997-12-02

Dysprosium-doped metal chloride materials offer laser properties advantageous for use as optical amplifiers in the 1.3 {micro}m telecommunications fiber optic network. The upper laser level is characterized by a millisecond lifetime, the host material possesses a moderately low refractive index, and the gain peak occurs near 1.31 {micro}m. Related halide materials, including bromides and iodides, are also useful. The Dy{sup 3+}-doped metal chlorides can be pumped with laser diodes and yield 1.3 {micro}m signal gain levels significantly beyond those currently available. 9 figs.

Optical amplifier operating at 1.3 microns useful for telecommunications and based on dysprosium-doped metal chloride host materials

DOEpatents

Page, Ralph H.; Schaffers, Kathleen I.; Payne, Stephen A.; Krupke, William F.; Beach, Raymond J.

1997-01-01

Dysprosium-doped metal chloride materials offer laser properties advantageous for use as optical amplifiers in the 1.3 .mu.m telecommunications fiber optic network. The upper laser level is characterized by a millisecond lifetime, the host material possesses a moderately low refractive index, and the gain peak occurs near 1.31 .mu.m. Related halide materials, including bromides and iodides, are also useful. The Dy.sup.3+ -doped metal chlorides can be pumped with laser diodes and yield 1.3 .mu.m signal gain levels significantly beyond those currently available.

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)

Dysprosium electrodeposition from a hexaalkylguanidinium-based ionic liquid

NASA Astrophysics Data System (ADS)

Berger, Claudia A.; Arkhipova, Maria; Maas, Gerhard; Jacob, Timo

2016-07-01

The rare-earth element dysprosium (Dy) is an important additive that increases the magnetocrystalline anisotropy of neodymium magnets and additionally prevents from demagnetizing at high temperatures. Therefore, it is one of the most important elements for high-tech industries and is mainly used in permanent magnetic applications, for example in electric vehicles, industrial motors and direct-drive wind turbines. In an effort to develop a more efficient electrochemical technique for depositing Dy on Nd-magnets in contrast to commonly used costly physical vapor deposition, we investigated the electrochemical behavior of dysprosium(iii) trifluoromethanesulfonate in a custom-made guanidinium-based room-temperature ionic liquid (RTIL). We first examined the electrodeposition of Dy on an Au(111) model electrode. The investigation was carried out by means of cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS). The initial stages of metal deposition were followed by in situ scanning tunneling microscopy (STM). CV measurements revealed a large cathodic reduction peak, which corresponds to the growth of monoatomic high islands, based on STM images taken during the initial stages of deposition. XPS identified these deposited islands as dysprosium. A similar reduction peak was also observed on an Nd-Fe-B substrate, and positively identified as deposited Dy using XPS. Finally, we varied the concentration of the Dy precursor, electrolyte flow and temperature during Dy deposition and demonstrated that each of these parameters could be used to increase the thickness of the Dy deposit, suggesting that these parameters could be tuned simultaneously in a temperature-controlled flow cell to enhance the thickness of the Dy layer.The rare-earth element dysprosium (Dy) is an important additive that increases the magnetocrystalline anisotropy of neodymium magnets and additionally prevents from demagnetizing at high temperatures. Therefore, it is one of the most important elements for high-tech industries and is mainly used in permanent magnetic applications, for example in electric vehicles, industrial motors and direct-drive wind turbines. In an effort to develop a more efficient electrochemical technique for depositing Dy on Nd-magnets in contrast to commonly used costly physical vapor deposition, we investigated the electrochemical behavior of dysprosium(iii) trifluoromethanesulfonate in a custom-made guanidinium-based room-temperature ionic liquid (RTIL). We first examined the electrodeposition of Dy on an Au(111) model electrode. The investigation was carried out by means of cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS). The initial stages of metal deposition were followed by in situ scanning tunneling microscopy (STM). CV measurements revealed a large cathodic reduction peak, which corresponds to the growth of monoatomic high islands, based on STM images taken during the initial stages of deposition. XPS identified these deposited islands as dysprosium. A similar reduction peak was also observed on an Nd-Fe-B substrate, and positively identified as deposited Dy using XPS. Finally, we varied the concentration of the Dy precursor, electrolyte flow and temperature during Dy deposition and demonstrated that each of these parameters could be used to increase the thickness of the Dy deposit, suggesting that these parameters could be tuned simultaneously in a temperature-controlled flow cell to enhance the thickness of the Dy layer. Electronic supplementary information (ESI) available. See DOI: 10.1039/C6NR01351A

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.

Effects of chemically induced contraction of a coordination polyhedron on the dynamical magnetism of bis(phthalocyaninato)disprosium, a single-4f-ionic single-molecule magnet with a Kramers ground state.

PubMed

Ishikawa, Naoto; Mizuno, Yoshifumi; Takamatsu, Satoshi; Ishikawa, Tadahiko; Koshihara, Shin-ya

2008-11-17

Chemically induced longitudinal contraction of the square-antiprism coordination polyhedron of a peripherically substituted bis(phthalocyaninato)dysprosiumate(III), a dysprosium-based single-4f-ionic single-molecule magnet having a J z = +/- (13)/ 2 Kramers doublet ground state, resulted in drastic changes in dynamical magnetism including a doubling of the energy barrier, a 2-order-of-magnitude decrease of the spin reversal rate, a significant rise of the blocking temperature, and the first observation of the emergence of a large remanent magnetization.

Accurate Determination of the Dynamical Polarizability of Dysprosium

NASA Astrophysics Data System (ADS)

Ravensbergen, C.; Corre, V.; Soave, E.; Kreyer, M.; Tzanova, S.; Kirilov, E.; Grimm, R.

2018-06-01

We report a measurement of the dynamical polarizability of dysprosium atoms in their electronic ground state at the optical wavelength of 1064 nm, which is of particular interest for laser trapping experiments. Our method is based on collective oscillations in an optical dipole trap, and reaches unprecedented accuracy and precision by comparison with an alkali atom (potassium) as a reference species. We obtain values of 184.4(2.4) and 1.7(6) a.u. for the scalar and tensor polarizability, respectively. Our experiments have reached a level that permits meaningful tests of current theoretical descriptions and provides valuable information for future experiments utilizing the intriguing properties of heavy lanthanide atoms.

Crystallographic phases in heavy rare earth metals under megabar pressures

NASA Astrophysics Data System (ADS)

Samudrala, G. K.; Vohra, Y. K.

2012-07-01

Experiments aimed at understanding the crystallographic phases of heavy rare earth metals were carried out in a diamond anvil cell at the Advanced Photon Source, Argonne National Laboratory. Heavy rare earth metals dysprosium (Dy), holmium (Ho), erbium (Er) and thulium (Tm) were compressed to multi-megabar pressures. The rare earth crystal sequence hcp→Sm-type→dhcp→distorted-fcc (dfcc) is observed in all four elements. Upon further compression, a structural transformation to a monoclinic C2/m phase has been observed. We summarize the results from these experiments and present Rietveld structural refinements on high pressure phases for the specific case of dysprosium.

Dosimetric properties of dysprosium doped calcium magnesium borate glass subjected to Co-60 gamma ray

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

Omar, R. S., E-mail: ratnasuffhiyanni@gmail.com; Wagiran, H., E-mail: husin@utm.my; Saeed, M. A.

Thermoluminescence (TL) dosimetric properties of dysprosium doped calcium magnesium borate (CMB:Dy) glass are presented. This study is deemed to understand the application of calcium as the modifier in magnesium borate glass with the presence of dysprosium as the activator to be performed as TL dosimeter (TLD). The study provides fundamental knowledge of a glass system that may lead to perform new TL glass dosimetry application in future research. Calcium magnesium borate glass systems of (70-y) B{sub 2}O{sub 3} − 20 CaO – 10 MgO-(y) Dy{sub 2}O{sub 3} with 0.05  mol % ≤ y ≤ 0.7  mol % of dyprosium weremore » prepared by melt-quenching technique. The amorphous structure and TL properties of the prepared samples were determined using powder X-ray diffraction (XRD) and TL reader; model Harshaw 4500 respectively. The samples were irradiated to Co-60 gamma source at a dose of 50 Gy. Dosimetric properties such as annealing procedure, time temperature profile (TTP) setting, optimization of Dy{sub 2}O{sub 3} concentration of 0.5 mol % were determined for thermoluminescence dosimeter (TLD) reader used.« less

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.

Two-species five-beam magneto-optical trap for erbium and dysprosium

NASA Astrophysics Data System (ADS)

Ilzhöfer, P.; Durastante, G.; Patscheider, A.; Trautmann, A.; Mark, M. J.; Ferlaino, F.

2018-02-01

We report on the first realization of a two-species magneto-optical trap (MOT) for the highly magnetic erbium and dysprosium atoms. The MOT operates on an intercombination line for the respective species. Owing to the narrow-line character of such a cooling transition and the action of gravity, we demonstrate a trap geometry employing only five beams in the orthogonal configuration. We observe that the mixture is cooled and trapped very efficiently, with up to 5 ×108 Er atoms and 109 Dy atoms at temperatures of about 10 μ K . Our results offer an ideal starting condition for the creation of a dipolar quantum mixture of highly magnetic atoms.

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".

Performance assessment of imaging plates for the JHR transfer Neutron Imaging System

NASA Astrophysics Data System (ADS)

Simon, E.; Guimbal, P. AB(; )

2018-01-01

The underwater Neutron Imaging System to be installed in the Jules Horowitz Reactor (JHR-NIS) is based on a transfer method using a neutron activated beta-emitter like Dysprosium. The information stored in the converter is to be offline transferred on a specific imaging system, still to be defined. Solutions are currently under investigation for the JHR-NIS in order to anticipate the disappearance of radiographic films commonly used in these applications. We report here the performance assessment of Computed Radiography imagers (Imaging Plates) performed at LLB/Orphée (CEA Saclay). Several imaging plate types are studied, in one hand in the configuration involving an intimate contact with an activated dysprosium foil converter: Fuji BAS-TR, Fuji UR-1 and Carestream Flex XL Blue imaging plates, and in the other hand by using a prototypal imaging plate doped with dysprosium and thus not needing any contact with a separate converter foil. The results for these imaging plates are compared with those obtained with gadolinium doped imaging plate used in direct neutron imaging (Fuji BAS-ND). The detection performances of the different imagers are compared regarding resolution and noise. The many advantages of using imaging plates over radiographic films (high sensitivity, linear response, high dynamic range) could palliate its lower intrinsic resolution.

Structure, magnetic behavior, and anisotropy of homoleptic trinuclear lanthanoid 8-quinolinolate complexes.

PubMed

Chilton, Nicholas F; Deacon, Glen B; Gazukin, Olga; Junk, Peter C; Kersting, Berthold; Langley, Stuart K; Moubaraki, Boujemaa; Murray, Keith S; Schleife, Frederik; Shome, Mahasish; Turner, David R; Walker, Julia A

2014-03-03

Three complexes of the form [Ln(III)3(OQ)9] (Ln = Gd, Tb, Dy; OQ = 8-quinolinolate) have been synthesized and their magnetic properties studied. The trinuclear complexes adopt V-shaped geometries with three bridging 8-quinolinolate oxygen atoms between the central and peripheral eight-coordinate metal atoms. The magnetic properties of these three complexes differ greatly. Variable-temperature direct-current (dc) magnetic susceptibility measurements reveal that the gadolinium and terbium complexes display weak antiferromagnetic nearest-neighbor magnetic exchange interactions. This was quantified in the isotropic gadolinium case with an exchangecoupling parameter of J = -0.068(2) cm(-1). The dysprosium compound displays weak ferromagnetic exchange. Variable-frequency and -temperature alternating-current magnetic susceptibility measurements on the anisotropic cases reveal that the dysprosium complex displays single-molecule-magnet behavior, in zero dc field, with two distinct relaxation modes of differing time scales within the same molecule. Analysis of the data revealed anisotropy barriers of Ueff = 92 and 48 K for the two processes. The terbium complex, on the other hand, displays no such behavior in zero dc field, but upon application of a static dc field, slow magnetic relaxation can be observed. Ab initio and electrostatic calculations were used in an attempt to explain the origin of the experimentally observed slow relaxation of the magnetization for the dysprosium complex.

Analysis of soft x-ray emission spectra of laser-produced dysprosium, erbium and thulium plasmas

NASA Astrophysics Data System (ADS)

Sheil, John; Dunne, Padraig; Higashiguchi, Takeshi; Kos, Domagoj; Long, Elaine; Miyazaki, Takanori; O'Reilly, Fergal; O'Sullivan, Gerard; Sheridan, Paul; Suzuki, Chihiro; Sokell, Emma; White, Elgiva; Kilbane, Deirdre

2017-03-01

Soft x-ray emission spectra of dysprosium, erbium and thulium ions created in laser-produced plasmas were recorded with a flat-field grazing-incidence spectrometer in the 2.5-8 nm spectral range. The ions were produced using an Nd:YAG laser of 7 ns pulse duration and the spectra were recorded at various power densities. The experimental spectra were interpreted with the aid of the Cowan suite of atomic structure codes and the flexible atomic code. At wavelengths above 5.5 nm the spectra are dominated by overlapping n = 4 - n = 4 unresolved transition arrays from adjacent ion stages. Below 6 nm, n = 4 - n = 5 transitions also give rise to a series of interesting overlapping spectral features.

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.

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 .

Preparation and properties of porous microspheres made from borate glass.

PubMed

Conzone, Samuel D; Day, Delbert E

2009-02-01

Dysprosium lithium-borate glass microspheres and particles, ranging from 45 to 150 microm in diameter, were reacted with a 0.25 M phosphate solution at 37 degrees C, whose pH was either 3 or 8.8. The glass reacted nonuniformly and was converted into a porous, amorphous, hydrated, dysprosium phosphate reaction product. The amorphous product had the same volume and shape (pseudomorphic) as the unreacted glass, and could be dried without cracking. After heating at 300 degrees C for 1 h, the amorphous reaction product had a specific surface area of approximately 200 m(2)/g, a pore size of approximately 30 nm, and nominal crushing strength of approximately 10 MPa. When the reaction product was heated to 600 degrees C for 15 min, the specific surface area decreased to approximately 90 m(2)/g and the nominal crushing strength increased to 35 MPa. Heating above 615 degrees C converted the amorphous dysprosium phosphate product into crystalline DyPO(4), which contained open porosity until heated above 800 degrees C for 15 min. Highly porous materials of different chemical composition can be prepared by chemically reacting a borate-based glass with an aqueous solution at low-temperature (<100 degrees C). These highly porous materials are easy to process, and are considered candidates for controlled drug delivery, catalysis, chromatographic separation, filtration, and as bioactive materials.

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.

Watt-level dysprosium fiber laser at 315 μm with 73% slope efficiency

NASA Astrophysics Data System (ADS)

Woodward, R. I.; Majewski, M. R.; Bharathan, G.; Hudson, D. D.; Fuerbach, A.; Jackson, S. D.

2018-04-01

Rare-earth-doped fiber lasers are emerging as promising high-power mid-infrared sources for the 2.6-3.0 {\\mu}m and 3.3-3.8 {\\mu}m regions based on erbium and holmium ions. The intermediate wavelength range, however, remains vastly underserved, despite prospects for important manufacturing and defense applications. Here, we demonstrate the potential of dysprosium-doped fiber to solve this problem, with a simple in-band pumped grating-stabilized linear cavity generating up to 1.06 W at 3.15 {\\mu}m. A slope efficiency of 73% with respect to launched power (77% relative to absorbed power) is achieved: the highest value for any mid-infrared fiber laser to date, to the best of our knowledge. Opportunities for further power and efficiency scaling are also discussed.

Systematic optimization of laser cooling of dysprosium

NASA Astrophysics Data System (ADS)

Mühlbauer, Florian; Petersen, Niels; Baumgärtner, Carina; Maske, Lena; Windpassinger, Patrick

2018-06-01

We report on an apparatus for cooling and trapping of neutral dysprosium. We characterize and optimize the performance of our Zeeman slower and 2D molasses cooling of the atomic beam by means of Doppler spectroscopy on a 136 kHz broad transition at 626 nm. Furthermore, we demonstrate the characterization and optimization procedure for the loading phase of a magneto-optical trap (MOT) by increasing the effective laser linewidth by sideband modulation. After optimization of the MOT compression phase, we cool and trap up to 10^9 atoms within 3 seconds in the MOT at temperatures of 9 μK and phase space densities of 1.7 \\cdot 10^{-5}, which constitutes an ideal starting point for loading the atoms into an optical dipole trap and for subsequent forced evaporative cooling.

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.

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.

Dysprosium complexes with mono-/di-carboxylate ligands—From simple dimers to 2D and 3D frameworks

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

Zhang, Yingjie, E-mail: yzx@ansto.gov.au; Bhadbhade, Mohan; Scales, Nicholas

2014-11-15

Four dysprosium (Dy) single carboxylates, a formate, a propionate, a butyrate and an oxalate have been synthesized and structurally characterized. The structure of Dy(HCO{sub 2}){sub 3} (1) contains nine-fold coordinated Dy polyhedra in perfect tricapped trigonal prisms. They are linked through trigonal O atoms forming 1D pillars which are further linked together through tricapped O atoms into a 3D pillared metal organic framework. The network structure is stable up to 360 °C. The structure of [Dy{sub 2}(C{sub 2}O{sub 4}){sub 3}(H{sub 2}O){sub 6}]·2.5H{sub 2}O (2) contains nine-fold coordinated Dy polyhedra linking together through μ{sub 2}-bridging oxalate anions into a 2D hexagonalmore » layered structure. Both [Dy{sub 2}(Pr){sub 6}(H{sub 2}O){sub 4}]·(HPr){sub 0.5} (3) [Pr=(C{sub 2}H{sub 5}CO{sub 2}){sup −1}] and [Dy{sub 2}(Bu){sub 6}(H{sub 2}O){sub 4}] (4) [Bu=(C{sub 3}H{sub 7}CO{sub 2}){sup −1}] have similar di-nuclear structures. The Raman vibration modes of the complexes have been investigated. - Graphical abstract: Four dysprosium (Dy) complexes with formate, propionate, butyrate and oxalate ligands have been synthesized and characterized. The Dy formato complex has a 3D pillared metal organic framework and the structure is stable up to 360 °C whilst the complexes with longer alkyl chained mono-carboxylates possess similar di-nuclear structures. The Dy oxalato complex has a 2D hexagonal (honeycomb-type) structure. Their Raman vibration modes have been investigated. - Highlights: • New Dysprosium complexes with formate, propionate, butyrate and oxalate ligands. • Crystal structures range from dimers to two and three dimensional frameworks. • Vibrational modes have been investigated and correlated to the structures. • The complexes are thermal robust and stable to over 300 °C.« less

Effect of NaFeEDTA-fortified soy sauce on zinc absorption in children.

PubMed

Li, Min; Wu, Jinghuan; Ren, Tongxiang; Wang, Rui; Li, Weidong; Piao, Jianhua; Wang, Jun; Yang, Xiaoguang

2015-03-01

NaFeEDTA has been applied in many foods as an iron fortificant and is used to prevent iron deficiency in Fe-depleted populations. In China, soy sauce is fortified with NaFeEDTA to control iron deficiency. However, it is unclear whether Fe-fortified soy sauce affects zinc absorption. To investigate whether NaFeEDTA-fortified soy sauce affects zinc absorption in children, sixty children were enrolled in this study and randomly assigned to three groups (10 male children and 10 female children in each group). All children received daily 3 mg of (67)Zn and 1.2 mg of dysprosium orally, while the children in the three groups were supplemented with NaFeEDTA-fortified soy sauce (6 mg Fe, NaFeEDTA group), FeSO₄-fortified soy sauce (6 mg Fe, FeSO₄ group), and no iron-fortified soy sauce (control group), respectively. Fecal samples were collected during the experimental period and analyzed for the Zn content, (67)Zn isotope ratio and dysprosium content. The Fe intake from NaFeEDTA-fortified and FeSO₄-fortified groups was significantly higher than that in the control group (P < 0.0001). The daily total Zn intake was not significantly different among the three groups. There were no significant differences in fractional Zn absorption (FZA) (P = 0.3895), dysprosium recovery (P = 0.7498) and Zn absorption (P = 0.5940) among the three groups. Therefore, NaFeEDTA-fortified soy sauce does not affect Zn bioavailability in children.

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.

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.

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.

Magnetic anisotropy of dysprosium(III) in a low-symmetry environment: a theoretical and experimental investigation.

PubMed

Bernot, Kevin; Luzon, Javier; Bogani, Lapo; Etienne, Mael; Sangregorio, Claudio; Shanmugam, Muralidharan; Caneschi, Andrea; Sessoli, Roberta; Gatteschi, Dante

2009-04-22

A mixed theoretical and experimental approach was used to determine the local magnetic anisotropy of the dysprosium(III) ion in a low-symmetry environment. The susceptibility tensor of the monomeric species having the formula [Dy(hfac)(3)(NIT-C(6)H(4)-OEt)(2)], which contains nitronyl nitroxide (NIT-R) radicals, was determined at various temperatures through angle-resolved magnetometry. These results are in agreement with ab initio calculations performed using the complete active space self-consistent field (CASSCF) method, validating the predictive power of this theoretical approach for complex systems containing rare-earth ions, even in low-symmetry environments. Susceptibility measurements performed with the applied field along the easy axis eventually permitted a detailed analysis of the temperature and field dependence of the magnetization, providing evidence that the Dy ion transmits an antiferromagnetic interaction between radicals but that the Dy-radical interaction is ferromagnetic.

Theoretical study of some experimentally relevant states of dysprosium

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

Dzuba, V. A.; Flambaum, V. V.

2010-05-15

Configuration interaction method is used to calculate transition amplitudes and other properties of the low states of dysprosium which are used in cooling and in the study of the time variation of the fine structure constant and violation of fundamental symmetries. The branching ratio for the cooling state to decay to states other than ground states is found to be smaller than 10{sup -4}. The matrix element of the weak interaction between degenerate states at E=19797.96 cm{sup -1} is about 4 Hz which is consistent with the experimental limit |H{sub W}|=|2.3{+-}2.9(stat.){+-}0.7(syst.)| Hz [A. T. Nguyen, D. Budker, D. DeMille, andmore » M. Zolotorev, Phys. Rev. A 56, 3453 (1997)] and points to feasibility of its experimental measurement. Applications include the search for physics beyond the standard model using the parity nonconservation (PNC) isotopic chain approach.« less

Extension of the energy range of the experimental activation cross-sections data of longer-lived products of proton induced nuclear reactions on dysprosium up to 65MeV.

PubMed

Tárkányi, F; Ditrói, F; Takács, S; Hermanne, A; Ignatyuk, A V

2015-04-01

Activation cross-sections data of longer-lived products of proton induced nuclear reactions on dysprosium were extended up to 65MeV by using stacked foil irradiation and gamma spectrometry experimental methods. Experimental cross-sections data for the formation of the radionuclides (159)Dy, (157)Dy, (155)Dy, (161)Tb, (160)Tb, (156)Tb, (155)Tb, (154m2)Tb, (154m1)Tb, (154g)Tb, (153)Tb, (152)Tb and (151)Tb are reported in the 36-65MeV energy range, and compared with an old dataset from 1964. The experimental data were also compared with the results of cross section calculations of the ALICE and EMPIRE nuclear model codes and of the TALYS nuclear reaction model code as listed in the latest on-line libraries TENDL 2013. Copyright © 2015. Published by Elsevier Ltd.

Radiative properties of ceramic metal-halide high intensity discharge lamps containing additives in argon plasma

NASA Astrophysics Data System (ADS)

Cressault, Yann; Teulet, Philippe; Zissis, Georges

2016-07-01

The lighting represents a consumption of about 19% of the world electricity production. We are thus searching new effective and environment-friendlier light sources. The ceramic metal-halide high intensity lamps (C-MHL) are one of the options for illuminating very high area. The new C-MHL lamps contain additives species that reduce mercury inside and lead to a richer spectrum in specific spectral intervals, a better colour temperature or colour rendering index. This work is particularly focused on the power radiated by these lamps, estimated using the net emission coefficient, and depending on several additives (calcium, sodium, tungsten, dysprosium, and thallium or strontium iodides). The results show the strong influence of the additives on the power radiated despite of their small quantity in the mixtures and the increase of visible radiation portion in presence of dysprosium.

Single-molecule magnet behavior in an octanuclear dysprosium(iii) aggregate inherited from helical triangular Dy3 SMM-building blocks.

PubMed

Zhang, Li; Zhang, Peng; Zhao, Lang; Wu, Jianfeng; Guo, Mei; Tang, Jinkui

2016-06-28

An unprecedented octanuclear dysprosium(iii) cluster with the formula [Dy8L6(μ3-OH)4(μ2-CH3O)2(CH3OH)6(H2O)2]·6H2O·10CH3OH·2CH3CN () based on a nonlinearly tritopic aroylhydrazone ligand H3L has been isolated, realizing the successful linking of pairwise interesting triangular Dy3 SMMs. It is noteworthy that two enantiomers (Λ and Δ configurations) individually behaving as a coordination-induced chirality presented in the Dy3 helicate are connected in the meso Dy8 cluster. Remarkably, alternating-current magnetic susceptibility measurements revealed that the Dy8 cluster shows typical SMM behavior inherited from its Dy3 helical precursor. It is one of the rare polynuclear Lnn SMMs (n > 7) under zero dc field.

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.

Resonance region measurements of dysprosium and rhenium

NASA Astrophysics Data System (ADS)

Leinweber, Gregory; Block, Robert C.; Epping, Brian E.; Barry, Devin P.; Rapp, Michael J.; Danon, Yaron; Donovan, Timothy J.; Landsberger, Sheldon; Burke, John A.; Bishop, Mary C.; Youmans, Amanda; Kim, Guinyun N.; Kang, yeong-rok; Lee, Man Woo; Drindak, Noel J.

2017-09-01

Neutron capture and transmission measurements have been performed, and resonance parameter analysis has been completed for dysprosium, Dy, and rhenium, Re. The 60 MeV electron accelerator at RPI Gaerttner LINAC Center produced neutrons in the thermal and epithermal energy regions for these measurements. Transmission measurements were made using 6Li glass scintillation detectors. The neutron capture measurements were made with a 16-segment NaI multiplicity detector. The detectors for all experiments were located at ≈25 m except for thermal transmission, which was done at ≈15 m. The dysprosium samples included one highly enriched 164Dy metal, 6 liquid solutions of enriched 164Dy, two natural Dy metals. The Re samples were natural metals. Their capture yield normalizations were corrected for their high gamma attenuation. The multi-level R-matrix Bayesian computer code SAMMY was used to extract the resonance parameters from the data. 164Dy resonance data were analyzed up to 550 eV, other Dy isotopes up to 17 eV, and Re resonance data up to 1 keV. Uncertainties due to resolution function, flight path, burst width, sample thickness, normalization, background, and zero time were estimated and propagated using SAMMY. An additional check of sample-to-sample consistency is presented as an estimate of uncertainty. The thermal total cross sections and neutron capture resonance integrals of 164Dy and Re were determined from the resonance parameters. The NJOY and INTER codes were used to process and integrate the cross sections. Plots of the data, fits, and calculations using ENDF/B-VII.1 resonance parameters are presented.

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

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.

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.

A rational approach to the modulation of the dynamics of the magnetisation in a dysprosium-nitronyl-nitroxide radical complex.

PubMed

Poneti, Giordano; Bernot, Kevin; Bogani, Lapo; Caneschi, Andrea; Sessoli, Roberta; Wernsdorfer, Wolfgang; Gatteschi, Dante

2007-05-14

A control of the dynamics of the magnetisation is chemically achieved in a ring-like Dy-radical based molecule, allowing the estimation of the quantum tunneling frequency with a (4)He-cooled susceptometer.

Dual responsive dysprosium-doped hydroxyapatite particles and toxicity reduction after functionalization with folic and glucuronic acids.

PubMed

Sánchez Lafarga, Ana Karen; Pacheco Moisés, Fermín P; Gurinov, Andrey; Ortiz, Genaro Gabriel; Carbajal Arízaga, Gregorio Guadalupe

2015-03-01

The development of probes for biomedical applications demands materials with low toxicity levels besides fluorescence or magnetic properties to be detected by confocal microscopes or MRI resonators. Several drug delivery systems or other biomedical materials prepared with hydroxyapatite have been proposed, however, toxicity effects might arise when the size of particles is nanometric. In this study, hydroxyapatite functionalized with glucuronic or folic acids presented lower oxidative stress, measured from lipoperoxides and nitric oxide indicators in rats than pure hydroxyapatite. In separated experiments, hydroxyapatite was doped with dysprosium cations by coprecipitation producing a single crystal phase with fluorescent properties easily visualized by confocal microscopy when excited at 488nm. These particles also presented the ability to modify the proton relaxation time in T1 maps collected by magnetic resonance imaging. These modified hydroxyapatite nanoparticles could be candidates to design bimodal probes with low toxicity. Copyright © 2014 Elsevier B.V. All rights reserved.

Magnetic ordering temperatures in rare earth metal dysprosium under ultrahigh pressures

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

Samudrala, Gopi K.; Tsoi, Georgiy M.; Weir, Samuel T.

Magnetic ordering temperatures in heavy rare earth metal Dysprosium (Dy) have been studied using an ultrasensitive electrical transport measurement technique in a designer diamond anvil cell to extreme conditions of pressure to 69 GPa and temperature to 10 K. Previous studies using magnetic susceptibility measurements at high pressures were only able to track magnetic ordering temperature till 7 GPa in the hexagonal close packed ( hcp) phase of Dy. Our studies indicate that the magnetic ordering temperature shows an abrupt drop of 80 K at the hcp-Sm phase transition followed by a gradual decrease that continues till 17 GPa. Thismore » is followed by a rapid increase in the magnetic ordering temperatures in the double hexagonal close packed phase and finally leveling off in the distorted face centered cubic phase of Dy. Lastly, our studies reaffirm that 4f-shell remain localized in Dy and there is no loss of magnetic moment or 4f-shell delocalization for pressures up to 69 GPa.« less

Collisional perturbation of radio-frequency E1 transitions in an atomic beam of dysprosium

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

Cingoez, A.; Lapierre, Alain; Nguyen, A.-T.

2005-12-15

We have studied collisional perturbations of radio-frequency (rf) electric-dipole (E1) transitions between the nearly degenerate opposite-parity levels in atomic dysprosium (Dy) in the presence of 10 to 80 {mu}Torr of H{sub 2}, N{sub 2}, He, Ar, Ne, Kr, and Xe. Collisional broadening and shift of the resonance, as well as the attenuation of the signal amplitude are observed to be proportional to the foreign-gas density with the exception of H{sub 2} and Ne, for which no shifts were observed. Corresponding rates and cross sections are presented. In addition, rates and cross sections for O{sub 2} are extracted from measurements usingmore » air as foreign gas. The primary motivation for this study is the need for accurate determination of the shift rates, which are needed in a laboratory search for the temporal variation of the fine-structure constant [A. T. Nguyen, D. Budker, S. K. Lamoreaux, and J. R. Torgerson, Phys. Rev. A 69, 22105 (2004)].« less

Limit on the temporal variation of the fine-structure constant using atomic dysprosium.

PubMed

Cingöz, A; Lapierre, A; Nguyen, A-T; Leefer, N; Budker, D; Lamoreaux, S K; Torgerson, J R

2007-01-26

Over 8 months, we monitored transition frequencies between nearly degenerate, opposite-parity levels in two isotopes of atomic dysprosium (Dy). These frequencies are sensitive to variation of the fine-structure constant (alpha) due to relativistic corrections of opposite sign for the opposite-parity levels. In this unique system, in contrast to atomic-clock comparisons, the difference of the electronic energies of the opposite-parity levels can be monitored directly utilizing a rf electric-dipole transition between them. Our measurements show that the frequency variation of the 3.1-MHz transition in (163)Dy and the 235-MHz transition in (162)Dy are 9.0+/-6.7 Hz/yr and -0.6+/-6.5 Hz/yr, respectively. These results provide a rate of fractional variation of alpha of (-2.7+/-2.6) x 10(-15) yr(-1) (1 sigma) without assumptions on constancy of other fundamental constants, indicating absence of significant variation at the present level of sensitivity.

Investigations on structural, optical and magnetic properties of Dy-doped zinc ferrite nanoparticles

NASA Astrophysics Data System (ADS)

Vinosha, P. Annie; Deepapriya, S.; Rodney, John. D.; Das, S. Jerome

2018-04-01

A persuasive and thriftily feasible homogeneous co-precipitation route was adopted to fabricate dysprosium (Dy) doped zinc ferrite (Zn1-xDyxFe2O4)nanoparticles in order to examine their structural, optical and magnetic properties. Theas-synthesized Zn1-xDyxFe2O4 was studied for its momentous applications in photo-degradation of organic Methylene Blue (MB) dye. The paper marksthe connotation of zinc ferrite nanocatalyst in Photo-Fenton degradation. The chemical composition of dysprosium has a decisive feature of this research work. From X-ray diffraction analysis (XRD), spinel phase formation of theas-synthesized Zn1-xDyxFe2O4 nanoparticles was observedand the crystallite size was foundto increase as the doping concentration increased. Theabsorption bands peaked between 600-400 cm-l waspragmatic by Fourier Transform Infrared spectral analysis (FTIR). Transmission Electron Microscopy (TEM) micrograph elucidated the morphology and the speck size of as-synthesized nanoparticles. Surface area and pore size were determined by Brunauer-Emmett-Teller (BET) technique.

Magnetic ordering temperatures in rare earth metal dysprosium under ultrahigh pressures

DOE PAGES

Samudrala, Gopi K.; Tsoi, Georgiy M.; Weir, Samuel T.; ...

2014-04-03

Magnetic ordering temperatures in heavy rare earth metal Dysprosium (Dy) have been studied using an ultrasensitive electrical transport measurement technique in a designer diamond anvil cell to extreme conditions of pressure to 69 GPa and temperature to 10 K. Previous studies using magnetic susceptibility measurements at high pressures were only able to track magnetic ordering temperature till 7 GPa in the hexagonal close packed ( hcp) phase of Dy. Our studies indicate that the magnetic ordering temperature shows an abrupt drop of 80 K at the hcp-Sm phase transition followed by a gradual decrease that continues till 17 GPa. Thismore » is followed by a rapid increase in the magnetic ordering temperatures in the double hexagonal close packed phase and finally leveling off in the distorted face centered cubic phase of Dy. Lastly, our studies reaffirm that 4f-shell remain localized in Dy and there is no loss of magnetic moment or 4f-shell delocalization for pressures up to 69 GPa.« less

Near-zero thermal expansion in magnetically ordered state in dysprosium at high pressures and low temperatures

NASA Astrophysics Data System (ADS)

Hope, Kevin M.; Samudrala, Gopi K.; Vohra, Yogesh K.

2017-01-01

The atomic volume of rare earth metal dysprosium (Dy) has been measured up to high pressures of 35 GPa and low temperatures between 200 and 7 K in a diamond anvil cell using angle dispersive X-ray diffraction at a synchrotron source. The hexagonal close-packed (hcp), alpha-Samarium (α-Sm), and double hexagonal close-packed (dhcp) phases are observed to be stable in Dy under high-pressure and low-temperature conditions achieved in our experiments. Dy is known to undergo magnetic ordering below 176 K at ambient pressure with magnetic ordering Néel temperature (TN) that changes rapidly with increasing pressure. Our experimental measurement shows that Dy has near-zero thermal expansion in the magnetically ordered state and normal thermal expansion in the paramagnetic state for all the three known high pressure phases (hcp, α-Sm, and dhcp) to 35 GPa. This near-zero thermal expansion behavior in Dy is observed below the magnetic ordering temperature TN at all pressures up to 35 GPa.

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.

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.

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.

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.

Edwin M. McMillan

Science.gov Websites

mixture. The separation of the different components in these compound earths has been no easy task, since terbium and dysprosium in the lanthanides. By irradiating different sorts of heavy atoms with neutrons Berkeley Lab Search Submit Web People Close About the Lab Leadership/Organization Calendar News Center

Single molecule magnet behaviour in robust dysprosium-biradical complexes.

PubMed

Bernot, Kevin; Pointillart, Fabrice; Rosa, Patrick; Etienne, Mael; Sessoli, Roberta; Gatteschi, Dante

2010-09-21

A Dy-biradical complex was synthesized and characterized down to very low temperature. ac magnetic measurements reveal single molecule magnet behaviour visible without any application of dc field. The transition to the quantum tunneling regime is evidenced. Photophysical and EPR measurements provide evidence of the excellent stability of these complexes in solution.

Isolation of 163Ho from dysprosium target material by HPLC for neutrino mass measurements

DOE PAGES

Mocko, Veronika; Taylor, Wayne  A.; Nortier, Francois M.; ...

2015-04-29

The rare earth isotope 163Ho is of interest for neutrino mass measurements. This report describes the isolation of 163Ho from a proton-irradiated dysprosium target and its purification. A Dy metal target was irradiated with 16 MeV protons for 10 h. After target dissolution, 163Ho was separated from the bulk Dy via cation-exchange high performance liquid chromatography using 70 mmol dm –3 α-hydroxyisobutyric acid as the mobile phase. Subsequent purification of the collected Ho fraction was performed to remove the α-hydroxyisobutyrate chelating agent and to concentrate the Ho in a low ionic strength aqueous matrix. The final solution was characterized bymore » MC-ICP-MS to determine the 163Ho/ 165Ho ratio, 163Ho and the residual Dy content. The HPLC purification process resulted in a decontamination factor 1.4E5 for Dy. As a result, the isolated Ho fraction contained 24.8 ±1.3 ng of 163Ho corresponding to holmium recovery of 72 ± 3%.« less

Dysprosium complexes with mono-/di-carboxylate ligands-From simple dimers to 2D and 3D frameworks

NASA Astrophysics Data System (ADS)

Zhang, Yingjie; Bhadbhade, Mohan; Scales, Nicholas; Karatchevtseva, Inna; Price, Jason R.; Lu, Kim; Lumpkin, Gregory R.

2014-11-01

Four dysprosium (Dy) single carboxylates, a formate, a propionate, a butyrate and an oxalate have been synthesized and structurally characterized. The structure of Dy(HCO2)3 (1) contains nine-fold coordinated Dy polyhedra in perfect tricapped trigonal prisms. They are linked through trigonal O atoms forming 1D pillars which are further linked together through tricapped O atoms into a 3D pillared metal organic framework. The network structure is stable up to 360 °C. The structure of [Dy2(C2O4)3(H2O)6]·2.5H2O (2) contains nine-fold coordinated Dy polyhedra linking together through μ2-bridging oxalate anions into a 2D hexagonal layered structure. Both [Dy2(Pr)6(H2O)4]·(HPr)0.5 (3) [Pr=(C2H5CO2)-1] and [Dy2(Bu)6(H2O)4] (4) [Bu=(C3H7CO2)-1] have similar di-nuclear structures. The Raman vibration modes of the complexes have been investigated.

Extraction of Dysprosium Ions with DTPA Functionalized Superparamagnetic Nanoparticles Probed by Energy Dispersive X-ray Fluorescence and TEM/High-Angle Annular Dark Field Imaging.

PubMed

Melo, Fernando Menegatti de; Almeida, Sabrina da Nobrega; Uezu, Noemi Saori; Ramirez, Carlos Alberto Ospina; Santos, Antonio Domingues Dos; Toma, Henrique Eisi

2018-06-01

The extraction of dysprosium (Dy3+) ions from aqueous solution was carried out successfully, using magnetite (Fe3O4) nanoparticles functionalized with diethylenetriaminepentaacetic acid (MagNP@DTPA). The process was monitored by energy dispersive X-ray fluorescence spectroscopy, as a function of concentration, proceeding according to a Langmuir isotherm with an equilibrium constant of 2.57 × 10-3 g(MagNP) L-1 and a saturation limit of 63.2 mgDy/gMagNP. The presence of paramagnetic Dy3+ ions attached to the superparamagnetic nanoparticles led to an overall decrease of magnetization. By imaging the nanoparticles surface using scanning transmission electron microscopy equipped with high resolution elemental analysis, it was possible to probe the binding of the Dy3+ ions to DTPA, and to show their distribution in a region of negative magnetic field gradients. This finding is coherent with the observed decrease of magnetization, associated with the antiferromagnetic coupling between the lanthanide ions and the Fe3O4 core.

Near-zero thermal expansion in magnetically ordered state in dysprosium at high pressures and low temperatures

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

Hope, Kevin M.; Samudrala, Gopi K.; Vohra, Yogesh K.

The atomic volume of rare earth metal Dysprosium (Dy) has been measured up to high pressures of 35 GPa and low temperatures between 200 K and 7 K in a diamond anvil cell using angle dispersive x-ray diffraction at a synchrotron source. The hexagonal close-packed (hcp), alpha-Samarium (α-Sm), and double hexagonal close packed (dhcp) phases are observed to be stable in Dy under high-pressure and low-temperature conditions achieved in our experiments. Dy is known to undergo magnetic ordering below 176 K at ambient pressure with magnetic ordering Néel temperature (T N) that changes rapidly with increasing pressure. Our experimental measurementmore » shows that Dy has near-zero thermal expansion in the magnetically ordered state and normal thermal expansion in the paramagnetic state for all the three known high pressure phases (hcp, α-Sm, and dhcp) to 35 GPa. This near-zero thermal expansion behavior in Dy is observed below the magnetic ordering temperature T N at all pressures up to 35 GPa.« less

Optical properties of zinc borotellurite glass doped with trivalent dysprosium ion

NASA Astrophysics Data System (ADS)

Ami Hazlin, M. N.; Halimah, M. K.; Muhammad, F. D.; Faznny, M. F.

2017-04-01

The zinc borotellurite doped with dysprosium oxide glass samples with chemical formula {[(TeO2) 0 . 7(B2O3) 0 . 3 ] 0 . 7(ZnO) 0 . 3 } 1 - x(Dy2O3)x (where x=0.01, 0.02, 0.03, 0.04 and 0.05 M fraction) were prepared by using conventional melt quenching technique. The structural and optical properties of the proposed glass systems were characterized by using X-ray diffraction (XRD) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, and UV-VIS spectroscopy. The amorphous nature of the glass systems is confirmed by using XRD technique. The infrared spectra of the glass systems indicate three obvious absorption bands which are assigned to BO3 and TeO4 vibrational groups. Based on the absorption spectra obtained, the direct and indirect optical band gaps, as well as the Urbach energy were calculated. It is observed that both the direct and indirect optical band gaps increase with the concentration of Dy3+ ions. On the other hand, the Urbach energy is observed to decrease as the concentration of Dy3+ ions increases.

Possibility for precise Weinberg-angle measurement in centrosymmetric crystals with axis

NASA Astrophysics Data System (ADS)

Mukhamedjanov, T. N.; Sushkov, O. P.

2006-03-01

We demonstrate that parity-nonconserving interaction due to the nuclear weak charge QW leads to a nonlinear magnetoelectric effect in centrosymmetric paramagnetic crystals. It is shown that the effect exists only in crystals with special symmetry axis k . Kinematically, the correlation (correction to energy) has the form HPNC∝QWE•[B×k](B•k) , where B and E are external magnetic and electric fields. This gives rise to the magnetic induction MPNC∝QW{k(B•[k×E])+[k×E](B•k)} . To be specific, we consider rare-earth-metal trifluorides and, in particular, dysprosium trifluoride which looks the most suitable for experiment. We estimate the optimal temperature for the experiment to be of a few kelvin. For the magnetic field B=1T and the electric field E=10kV/cm , the expected magnetic induction is 4πMPNC˜0.5×10-11G , six orders of magnitude larger than the best sensitivity currently under discussion. Dysprosium has several stable isotopes, and so comparison of the effects for different isotopes provides the possibility for precise measurement of the Weinberg angle.

Near-zero thermal expansion in magnetically ordered state in dysprosium at high pressures and low temperatures

DOE PAGES

Hope, Kevin M.; Samudrala, Gopi K.; Vohra, Yogesh K.

2017-01-01

The atomic volume of rare earth metal Dysprosium (Dy) has been measured up to high pressures of 35 GPa and low temperatures between 200 K and 7 K in a diamond anvil cell using angle dispersive x-ray diffraction at a synchrotron source. The hexagonal close-packed (hcp), alpha-Samarium (α-Sm), and double hexagonal close packed (dhcp) phases are observed to be stable in Dy under high-pressure and low-temperature conditions achieved in our experiments. Dy is known to undergo magnetic ordering below 176 K at ambient pressure with magnetic ordering Néel temperature (T N) that changes rapidly with increasing pressure. Our experimental measurementmore » shows that Dy has near-zero thermal expansion in the magnetically ordered state and normal thermal expansion in the paramagnetic state for all the three known high pressure phases (hcp, α-Sm, and dhcp) to 35 GPa. This near-zero thermal expansion behavior in Dy is observed below the magnetic ordering temperature T N at all pressures up to 35 GPa.« less

Isolation of 163Ho from dysprosium target material by HPLC for neutrino mass measurements

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

Mocko, Veronika; Taylor, Wayne  A.; Nortier, Francois M.

The rare earth isotope 163Ho is of interest for neutrino mass measurements. This report describes the isolation of 163Ho from a proton-irradiated dysprosium target and its purification. A Dy metal target was irradiated with 16 MeV protons for 10 h. After target dissolution, 163Ho was separated from the bulk Dy via cation-exchange high performance liquid chromatography using 70 mmol dm –3 α-hydroxyisobutyric acid as the mobile phase. Subsequent purification of the collected Ho fraction was performed to remove the α-hydroxyisobutyrate chelating agent and to concentrate the Ho in a low ionic strength aqueous matrix. The final solution was characterized bymore » MC-ICP-MS to determine the 163Ho/ 165Ho ratio, 163Ho and the residual Dy content. The HPLC purification process resulted in a decontamination factor 1.4E5 for Dy. As a result, the isolated Ho fraction contained 24.8 ±1.3 ng of 163Ho corresponding to holmium recovery of 72 ± 3%.« less

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.

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

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.

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.

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

Characterization and Luminescence Properties of Color-Tunable Dy3+-Doped BaY2ZnO5 Nanophosphors

NASA Astrophysics Data System (ADS)

Sonika; Khatkar, S. P.; Khatkar, Avni; Kumar, Rajesh; Taxak, V. B.

2015-01-01

Dy3+-doped BaY2ZnO5 nanophosphors were successfully synthesized by use of a solution combustion process. The effects of sintering temperature and dysprosium concentration on the structural and luminescence characteristics of the phosphors were investigated. X-ray diffraction (XRD) analysis confirmed the formation of pure orthorhombic BaY2ZnO5 with the space group Pbnm at 1100°C. Morphological investigation revealed spherical nanoparticles with smooth surfaces. The luminescence features of the nanophosphor were studied by use of photoluminescence excitation (PLE) and photoluminescence emission (PL), with luminescence decay curves and color ( x, y) coordinates. On excitation at 355 nm, BaY2ZnO5 nanophosphor doped with trivalent dysprosium ion emits white light as a mixture of blue (4F9/2 → 6H15/2) and yellow (4F9/2 → 6H13/2) emission. Concentration quenching is explained on the basis of cross-relaxation between intermediate Dy3+ states. Thus, BaY2ZnO5:Dy3+ nanophosphor may be suitable for producing efficient white light for ultraviolet-light-emitting diodes (UV-LEDs), fluorescent lamps, and a variety of optical display panels.

Paramagnetic dysprosium-doped zinc oxide thin films grown by pulsed-laser deposition

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

Lo, Fang-Yuh, E-mail: fangyuhlo@ntnu.edu.tw; Ting, Yi-Chieh; Chou, Kai-Chieh

2015-06-07

Dysprosium(Dy)-doped zinc oxide (Dy:ZnO) thin films were fabricated on c-oriented sapphire substrate by pulsed-laser deposition with doping concentration ranging from 1 to 10 at. %. X-ray diffraction (XRD), Raman-scattering, optical transmission spectroscopy, and spectroscopic ellipsometry revealed incorporation of Dy into ZnO host matrix without secondary phase. Solubility limit of Dy in ZnO under our deposition condition was between 5 and 10 at. % according to XRD and Raman-scattering characteristics. Optical transmission spectroscopy and spectroscopic ellipsometry also showed increase in both transmittance in ultraviolet regime and band gap of Dy:ZnO with increasing Dy density. Zinc vacancies and zinc interstitials were identified by photoluminescencemore » spectroscopy as the defects accompanied with Dy incorporation. Magnetic investigations with a superconducting quantum interference device showed paramagnetism without long-range order for all Dy:ZnO thin films, and a hint of antiferromagnetic alignment of Dy impurities was observed at highest doping concentration—indicating the overall contribution of zinc vacancies and zinc interstitials to magnetic interaction was either neutral or toward antiferromagnetic. From our investigations, Dy:ZnO thin films could be useful for spin alignment and magneto-optical applications.« less

New limits on variation of the fine-structure constant using atomic dysprosium.

PubMed

Leefer, N; Weber, C T M; Cingöz, A; Torgerson, J R; Budker, D

2013-08-09

We report on the spectroscopy of radio-frequency transitions between nearly degenerate, opposite-parity excited states in atomic dysprosium (Dy). Theoretical calculations predict that these states are very sensitive to variation of the fine-structure constant α owing to large relativistic corrections of opposite sign for the opposite-parity levels. The near degeneracy reduces the relative precision necessary to place constraints on variation of α, competitive with results obtained from the best atomic clocks in the world. Additionally, the existence of several abundant isotopes of Dy allows isotopic comparisons that suppress common-mode systematic errors. The frequencies of the 754-MHz transition in 164Dy and 235-MHz transition in 162Dy are measured over the span of two years. The linear variation of α is α·/α=(-5.8±6.9([1σ]))×10(-17)  yr(-1), consistent with zero. The same data are used to constrain the dimensionless parameter kα characterizing a possible coupling of α to a changing gravitational potential. We find that kα=(-5.5±5.2([1σ]))×10(-7), essentially consistent with zero and the best constraint to date.

Thermoluminescence properties of lithium magnesium borate glasses system doped with dysprosium oxide.

PubMed

Mhareb, M H A; Hashim, S; Ghoshal, S K; Alajerami, Y S M; Saleh, M A; Razak, N A B; Azizan, S A B

2015-12-01

We report the impact of dysprosium (Dy(3+)) dopant and magnesium oxide (MgO) modifier on the thermoluminescent properties of lithium borate (LB) glass via two procedures. The thermoluminescence (TL) glow curves reveal a single prominent peak at 190 °C for 0.5 mol% of Dy(3+). An increase in MgO contents by 10 mol% enhances the TL intensity by a factor of 1.5 times without causing any shift in the maximum temperature. This enhancement is attributed to the occurrence of extra electron traps created via magnesium and the energy transfer to trivalent Dy(3+) ions. Good linearity in the range of 0.01-4 Gy with a linear correlation coefficient of 0.998, fading as low as 21% over a period of 3 months, excellent reproducibility without oven annealing and tissue equivalent effective atomic numbers ~8.71 are achieved. The trap parameters, including geometric factor (μg), activation energy (E) and frequency factor (s) associated with LMB:Dy are also determined. These favorable TL characteristics of prepared glasses may contribute towards the development of Li2O-MgO-B2O3 radiation dosimeters. Copyright © 2015 John Wiley & Sons, Ltd.

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.

An experimental analysis of a doped lithium fluoride direct absorption solar receiver

NASA Technical Reports Server (NTRS)

Kesseli, James; Pollak, Tom; Lacy, Dovie

1988-01-01

An experimental analysis of two key elements of a direct absorption solar receiver for use with Brayton solar dynamic systems was conducted. Experimental data are presented on LiF crystals doped with dysprosium, samarium, and cobalt fluorides. In addition, a simulation of the cavity/window environment was performed and a posttest inspection was conducted to evaluate chemical reactivity, transmissivity, and condensation rate.

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.

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.

Laser Materials Search and Characterization

DTIC Science & Technology

2014-05-30

AgBr doped with dysprosium ions are obtained by extrusion, and their optical and spectral properties are studied. Task 3. Waveguides based on LiF...fluoride are obtained by extrusion for the first time. Task 4. Spectroscopic properties of Dy3+ ions in chalcogenide crystals and fibers are studied...Task 5. Crystals and ceramics doped with rare-earth ions , as well as glasses and crystals doped with bismuth ions , are synthesized. Their

Workplace testing of the new single sphere neutron spectrometer based on Dysprosium activation foils (Dy-SSS)

NASA Astrophysics Data System (ADS)

Bedogni, R.; Gómez-Ros, J. M.; Esposito, A.; Gentile, A.; Chiti, M.; Palacios-Pérez, L.; Angelone, M.; Tana, L.

2012-08-01

A photon insensitive passive neutron spectrometer consisting of a single moderating polyethylene sphere with Dysprosium activation foils arranged along three perpendicular axes was designed by CIEMAT and INFN. The device is called Dy-SSS (Dy foil-based Single Sphere Spectrometer). It shows nearly isotropic response in terms of neutron fluence up to 20 MeV. The first prototype, previously calibrated with 14 MeV neutrons, has been recently tested in workplaces having different energy and directional distributions. These are a 2.5 MeV nearly mono-chromatic and mono-directional beam available at the ENEA Frascati Neutron Generator (FNG) and the photo-neutron field produced in a 15 MV Varian CLINAC DHX medical accelerator, located in the Ospedale S. Chiara (Pisa). Both neutron spectra are known through measurements with a Bonner Sphere Spectrometer. In both cases the experimental response of the Dy-SSS agrees with the reference data. Moreover, it is demonstrated that the spectrometric capability of the new device are independent from the directional distribution of the neutron field. This opens the way to a new generation of moderation-based neutron instruments, presenting all advantages of the Bonner sphere spectrometer without the disadvantage of the repeated exposures. This concept is being developed within the NESCOFI@BTF project of INFN (Commissione Scientifica Nazionale 5).

Dysprosium-Modified Tobacco Mosaic Virus Nanoparticles for Ultra-High-Field Magnetic Resonance and Near-Infrared Fluorescence Imaging of Prostate Cancer.

PubMed

Hu, He; Zhang, Yifan; Shukla, Sourabh; Gu, Yuning; Yu, Xin; Steinmetz, Nicole F

2017-09-26

The increasing prevalence of ultra-high-field magnetic resonance imaging (UHFMRI) in biomedical research and clinical settings will improve the resolution and diagnostic accuracy of MRI scans. However, better contrast agents are needed to achieve a satisfactory signal-to-noise ratio. Here, we report the synthesis of a bimodal contrast agent prepared by loading the internal cavity of tobacco mosaic virus (TMV) nanoparticles with a dysprosium (Dy 3+ ) complex and the near-infrared fluorescence (NIRF) dye Cy7.5. The external surface of TMV was conjugated with an Asp-Gly-Glu-Ala (DGEA) peptide via a polyethylene glycol linker to target integrin α 2 β 1 . The resulting nanoparticle (Dy-Cy7.5-TMV-DGEA) was stable and achieved a high transverse relaxivity in ultra-high-strength magnetic fields (326 and 399 mM -1 s -1 at 7 and 9.4 T, respectively). The contrast agent was also biocompatible (low cytotoxicity) and targeted PC-3 prostate cancer cells and tumors in vitro and in vivo as confirmed by bimodal NIRF imaging and T 2 -mapping UHFMRI. Our results show that Dy-Cy7.5-TMV-DGEA is suitable for multiscale MRI scanning from the cellular level to the whole body, particularly in the context of UHFMRI applications.

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.

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.

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.

Application of Atomic Fluorescence to Measurement of Combustion Temperature in Solid Propellants.

DTIC Science & Technology

1986-12-04

into a cytal (yttrium- aluminum -garnet) is shown to be an ideal seed, the fluoresce. f which is stimulated by the ultra-violet output of a Nd:YAG...been successfully employed in atmospheric flames for making thermometric measurements. However, because of the amorphous nature of energetic materials...be determined. R. 6 A .6 An example of this type of behavior is found in trivalent dysprosium, doped at 3% in yttrium- aluminum -garnet (Dy+3 :YAG

Surface Thermometry of Energetic Materials by Laser-Induced Fluorescence

DTIC Science & Technology

1989-09-01

at 34 yttrium- aluminum -garnet (Dy:YAG). The simplified energy diagram of Dy:YAG is shown in Fig. 1. Absorbed laser light (at 355 nrm) can 5 excite the...the thermometric technique on a surface similar to that of an energetic material, a thermal-setting plastic supplied by Buehler, Ltd., was employed...temperature over the temperature range of interest. The rare-earth ion dysprosium (Dy) doped into a yttrium- aluminum -garnet (YAG) crystal was I determined

Thermal, optical and structural properties of Dy3+ doped sodium aluminophosphate glasses

NASA Astrophysics Data System (ADS)

Kaur, Manpreet; Singh, Anupinder; Thakur, Vanita; Singh, Lakhwant

2016-03-01

Trivalent Dysprosium doped sodium aluminophosphate glasses with composition 50P2O5-10Al2O3-(20-x)Na2O-20CaO-xDy2O3 (x varying from 0 to 5 mol%) were prepared by melt quench technique. The density of the prepared samples was measured using Archimedes principle and various physical properties like molar volume, rare earth ion concentration, polaron radius, inter nuclear distance and field strength were calculated using different formulae. The differential scanning calorimetry (DSC) was carried out to study the thermal stability of prepared glasses. The UV Visible absorption spectra of the dysprosium doped glasses were found to be comprised of ten absorption bands which correspond to transitions from ground state 6H15/2 to various excited states. The indirect optical band gap energy of the samples was calculated by Tauc's plot and the optical energy was found to be attenuated with Dy3+ ions. The photoluminescence spectrum revealed that Dy3+ doped aluminophosphate glasses have strong emission bands in the visible region. A blue emission band centred at 486 nm, a bright yellow band centred at 575 nm and a weak red band centred at 668 nm were observed in the emission spectrum due to excitation at 352 nm wavelength. Both FTIR and Raman spectra assert slight structural changes induced in the host glass network with Dy3+ ions.

Dual-mode T1 and T2 magnetic resonance imaging contrast agent based on ultrasmall mixed gadolinium-dysprosium oxide nanoparticles: synthesis, characterization, and in vivo application

NASA Astrophysics Data System (ADS)

Tegafaw, Tirusew; Xu, Wenlong; Wasi Ahmad, Md; Baeck, Jong Su; Chang, Yongmin; Bae, Ji Eun; Chae, Kwon Seok; Kim, Tae Jeong; Lee, Gang Ho

2015-09-01

A new type of dual-mode T1 and T2 magnetic resonance imaging (MRI) contrast agent based on mixed lanthanide oxide nanoparticles was synthesized. Gd3+ (8S7/2) plays an important role in T1 MRI contrast agents because of its large electron spin magnetic moment resulting from its seven unpaired 4f-electrons, and Dy3+ (6H15/2) has the potential to be used in T2 MRI contrast agents because of its very large total electron magnetic moment: among lanthanide oxide nanoparticles, Dy2O3 nanoparticles have the largest magnetic moments at room temperature. Using these properties of Gd3+ and Dy3+ and their oxide nanoparticles, ultrasmall mixed gadolinium-dysprosium oxide (GDO) nanoparticles were synthesized and their potential to act as a dual-mode T1 and T2 MRI contrast agent was investigated in vitro and in vivo. The D-glucuronic acid coated GDO nanoparticles (davg = 1.0 nm) showed large r1 and r2 values (r2/r1 ≈ 6.6) and as a result clear dose-dependent contrast enhancements in R1 and R2 map images. Finally, the dual-mode imaging capability of the nanoparticles was confirmed by obtaining in vivo T1 and T2 MR images.

Development of Nanomaterials for Nuclear Energetics

NASA Astrophysics Data System (ADS)

Petrunin, V. F.

Structure and properties peculiarities of the nanocrystalline powders give the opportunity to design new and to develop a modernization of nuclear energy industry materials. It was shown experimentally, that addition of 5-10% uranium dioxide nanocrystalline powder to traditional coarse powder allows to decrease the sintering temperature or to increase the fuel tablets size of grain. Similar perspectives for the technology of neutron absorbing tablets of control-rod modernization are shown by nanopowder of dysprosium hafnate changing instead now using boron carbide. It is powders in nanocrystalline state get an opportunity to sinter them and to receive compact tablet with 8,2-8,4 g/cm2 density for automatic defence system of nuclear reactor. Resource of dysprosium hafnate ceramics can be 18-20 years instead 4-5 years for boron carbide. To step up the radiation-damage stability of fuel element jacket material was suggested to strengthen a heat-resistant ferrite-martensite steel by Y2O3 nanocrystalline powder addition. Nanopowder with size of particles 560 nm and crystallite size 9 nm was prepeared by chemical coprecipitation method. To make lighter the container for transport and provisional disposal of exposed fuel from nuclear reactor a new boron-aluminium alloy called as boral was developed. This composite armed with nanopowders of boron-containing materials and heavy metals oxides can replace succesburnt-up corrosion-resistant steels.

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.

Rare-earth Doped GaN - An Innovative Path Toward Area-scalable Solid-state High Energy Lasers Without Thermal Distortion (2nd year)

DTIC Science & Technology

2010-06-01

heat removal technique and its efficiency , the gain medium itself is the bottleneck for non-distortive heat removal―simply due to low thermal...dysprosium (Dy) has been demonstrated by photoluminescence (PL), electroluminescence (EL), and/or cathodoluminescence (CL) (2, 3). As the RE dopant...provides the highest level of laser efficiency due to the pump and signal mode confinement within a crystalline-guided structure) has been designed. The

Surface analysis of model systems: From a metal-graphite interface to an intermetallic catalyst

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

Kwolek, Emma J.

This thesis summarizes research completed on two different model systems. In the first system, we investigate the deposition of the elemental metal dysprosium on highly-oriented pyrolytic graphite (HOPG) and its resulting nucleation and growth. The goal of this research is to better understand the metal-carbon interactions that occur on HOPG and to apply those to an array of other carbon surfaces. This insight may prove beneficial to developing and using new materials for electronic applications, magnetic applications and catalysis.

On the specific electrophysical properties of n-InSe single crystals

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

Abdinov, A. Sh., E-mail: abdinov-axmed@yahoo.com; Babaeva, R. F., E-mail: babaeva-rena@yandex.ru; Rzaev, R. M., E-mail: abdinov-axmed@yandex.ru

2016-01-15

The temperature dependences of physical parameters (the conductivity and the Hall constant) are experimentally investigated for pure indium-selenide (n-InSe) crystals and those lightly doped with rareearth elements (gadolinium, holmium, and dysprosium). It is established that the obtained results depend on the origin of the samples under investigation and prove to be contradictory for different samples. The obtained experimental results are treated taking into account the presence of chaotic large-scale defects and drift barriers caused by them in these samples.

Static high-pressure structural studies on Dy to 119 GPa

NASA Astrophysics Data System (ADS)

Patterson, Reed; Saw, Cheng K.; Akella, Jagannadham

2004-05-01

Structural phase transitions in the rare-earth metal dysprosium have been studied in a diamond anvil cell to 119 GPa by x-ray diffraction. Four transformations following the sequence hcp→Sm-type→dhcp→hR24 (hexagonal)→bcm (monoclinic) are observed at 6, 15, 43, and 73 GPa, respectively. The hexagonal to monoclinic transformation is accompanied by a 6% reduction in volume, which is attributed to delocalization of the 4f electrons, similar to that seen in Ce, Pr, and Gd.

Using T2-Exchange from Ln3+DOTA-Based Chelates for Contrast-Enhanced Molecular Imaging of Prostate Cancer with MRI

DTIC Science & Technology

2015-04-01

antigen ( PSMA ) of prostate cancer cells would then be synthesized and tested with both in vitro and in vivo experiments. Major Findings: We found that the...simplified chemistry. 15. SUBJECT TERMS MRI Contrast Agent, T2 contrast, Prostate Cancer, PSMA Targeted Agent, Early Detection and Diagnosis, Dysprosium... PSMA ), which is significantly over-expressed by prostate cancer cells, has proven to be an excellent target for imaging prostate cancer in mouse

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.

Dysprosium-sensitized chemiluminescence system for the determination of enoxacin in pharmaceutical preparations and biological fluids with flow-injection sampling.

PubMed

Sun, Han-wen; Wu, Yuan-yuan; Li, Li-qing

2009-03-01

A novel trivalence dysprosium(Dy(3+))-sensitized chemiluminescence method was developed for the first time for the determination of enoxacin (ENX) using flow-injection sampling based on the chemiluminescence (CL) associated with the reaction of the Dy(3+)-cerium(Ce(IV))-S(2)O(3) (2-)-ENX system and the Dy(3+)-MnO(4) (-) S(2)O(3) (2-)-ENX system. The analytical conditions for CL emission were investigated and optimized. The relationship between the CL intensity of ENX and its concentration has good linearity, with a correlation coefficient of 0.9984-0.9994. The limit of detection (LOD, 3sigma) was 0.20 ng/mL for the Dy(3+)-ENX-S(2)O(3)(2-)-Ce(IV)-H(2)SO(4) system and 0.22 ng/mL for the Dy(3+)-ENX-S(2)O(3)(2-)-MnO(4) (-)-HNO(3) system. The relative standard deviation (RSD, n = 11) was 1.8% for 11 determinations of 60 ng/mL ENX. The proposed method was applied to the analysis of ENX in injections, serum and urine samples with a recovery of 98%-105%. A possible mechanism for this sensitized CL reaction is discussed by comparing the CL spectra with the fluorescence emission spectra. The proposed method represents a wide linear range, high sensitivity and accuracy, and can be used for the routine determination of ENX in pharmaceutical preparations and biological fluids. Copyright 2009 John Wiley & Sons, Ltd.

Zinc Absorption from Representative Diet in a Chinese Elderly Population Using Stable Isotope Technique.

PubMed

Li, Ya Jie; Li, Min; Liu, Xiao Bing; Ren, Tong Xiang; Li, Wei Dong; Yang, Chun; Wu, Meng; Yang, Lin Li; Ma, Yu Xia; Wang, Jun; Piao, Jian Hua; Yang, Li Chen; Yang, Xiao Guang

2017-06-01

To determine the dietary zinc absorption in a Chinese elderly population and provide the basic data for the setting of zinc (Zn) recommended nutrient intakes (RNI) for Chinese elderly people. A total of 24 elderly people were recruited for this study and were administered oral doses of 3 mg 67Zn and 1.2 mg dysprosium on the fourth day. The primary macronutrients, energy, and phytic acid in the representative diet were examined based on the Chinese National Standard Methods. Fecal samples were collected during the experimental period and analyzed for zinc content, 67Zn isotope ratio, and dysprosium content. The mean (± SD) zinc intake from the representative Chinese diet was 10.6 ± 1.5 mg/d. The phytic acid-to-zinc molar ratio in the diet was 6.4. The absorption rate of 67Zn was 27.9% ± 9.2%. The RNI of zinc, which were calculated by the absorption rate in elderly men and women, were 10.4 and 9.2 mg/d, respectively. This study got the dietary Zn absorption in a Chinese elderly population. We found that Zn absorption was higher in elderly men than in elderly women. The current RNI in elderly female is lower than our finding, which indicates that more attention is needed regarding elderly females' zinc status and health. Copyright © 2017 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. 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.

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

Chasteler, R.M.; Nitschke, J.M.; Firestone, R.B.

Neutron-rich rare-earth isotopes were produced in multinucleon transfer reactions between {sup 170}Er ions and {sup nat}W targets. On-line mass separation was used together with {beta}- and {gamma}-ray spectroscopy in these studies. At mass {ital A}=169, the heaviest known dysprosium isotope, 39(8) s,{sup 169}Dy, was identified. It was observed to {beta}{sup {minus}} decay to the ground state of {sup 169}Ho or through a level at 1578 keV. In the {ital A}=171 mass chain, a partial decay scheme for 55(3)-s {sup 171}Ho was determined.

Laser spectroscopy of phonons and rotons in superfluid helium doped with Dy atoms

NASA Astrophysics Data System (ADS)

Moroshkin, P.; Borel, A.; Kono, K.

2018-03-01

We report the results of a high-resolution laser-spectroscopy study of dysprosium atoms injected into superfluid 4He. A special attention is paid to the transitions between the inner 4 f and 5 d electronic shells of Dy. The characteristic gap is observed between the zero-phonon line and the phonon wing in the experimental excitation spectrum that arises due to the peculiar structure of the phonon-roton spectrum of superfluid He. This observation resolves the longstanding discrepancy between the studies of bulk superfluid He and He nanodroplets.

Static High Pressure Structural studies on Dy to 119 GPa

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

Patterson, J R; Saw, C K; Akella, J

2003-11-12

Structural phase transitions in the rare-earth metal Dysprosium have been studied in a Diamond Anvil Cell (DAC) to 119 GPa by x-ray diffraction. Four transformations following the sequence hcp {yields} Sm-type {yields} dhcp {yields} hR24 (hexagonal) {yields} bcm (monoclinic) are observed at 6, 15, 43, and 73 GPa respectively. The hexagonal to monoclinic transformation is accompanied by a 6% reduction in volume, which is attributed to delocalization of the 4f electrons, similar to that seen in Ce, Pr, and Gd.

A Tunable and Enantioselective Hetero-Diels-Alder Reaction Provides Access to Distinct Piperidinoyl Spirooxindoles.

PubMed

Jayakumar, Samydurai; Louven, Kathrin; Strohmann, Carsten; Kumar, Kamal

2017-12-11

The active complexes of chiral N,N'-dioxide ligands with dysprosium and magnesium salts catalyze the hetero-Diels-Alder reaction between 2-aza-3-silyloxy-butadienes and alkylidene oxindoles to selectively form 3,3'- and 3,4'-piperidinoyl spirooxindoles, respectively, in very high yields and with excellent enantioselectivities. The exo-selective asymmetric cycloaddition successfully regaled the construction of sp 3 -rich and highly substituted natural-product-based spirooxindoles supporting many chiral centers, including contiguous all-carbon quaternary centers. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

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.

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.

Decay of the neutron-rich isotope 171Ho and the identification of 169Dy

NASA Astrophysics Data System (ADS)

Chasteler, R. M.; Nitschke, J. M.; Firestone, R. B.; Vierinen, K. S.; Wilmarth, P. A.

1990-10-01

Neutron-rich rare-earth isotopes were produced in multinucleon transfer reactions between 170Er ions and natW targets. On-line mass separation was used together with β- and γ-ray spectroscopy in these studies. At mass A=169, the heaviest known dysprosium isotope, 39(8) s,169Dy, was identified. It was observed to β- decay to the ground state of 169Ho or through a level at 1578 keV. In the A=171 mass chain, a partial decay scheme for 55(3)-s 171Ho was determined.

Alaska's rare earth deposits and resource potential

USGS Publications Warehouse

Barker, James C.; Van Gosen, Bradley S.

2012-01-01

Alaska’s known mineral endowment includes some of the largest and highest grade deposits of various metals, including gold, copper and zinc. Recently, Alaska has also been active in the worldwide search for sources of rare earth elements (REE) to replace exports now being limitedby China. Driven by limited supply of the rare earths, combined with their increasing use in new ‘green’ energy, lighting, transportation, and many other technological applications, the rare earth metals neodymium, europium and, in particular, the heavy rare earth elements terbium, dysprosium and yttrium are forecast to soon be in critical short supply (U.S. Department of Energy, 2010).

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

Drryl P. Butt; Brian Jaques

Research conducted for this NERI project has advanced the understanding and feasibility of nitride nuclear fuel processing. In order to perform this research, necessary laboratory infrastructure was developed; including basic facilities and experimental equipment. Notable accomplishments from this project include: the synthesis of uranium, dysprosium, and cerium nitrides using a novel, low-cost mechanical method at room temperature; the synthesis of phase pure UN, DyN, and CeN using thermal methods; and the sintering of UN and (Ux, Dy1-x)N (0.7 ≤ X ≤ 1) pellets from phase pure powder that was synthesized in the Advanced Materials Laboratory at Boise State University.

Controlling the width of self-assembled dysprosium silicide nanowires on the Si(001) surface.

PubMed

Cui, Y; Chung, J; Nogami, J

2012-02-01

We present STM data that show that it is possible to use a metal induced 2 × 7 reconstruction of Si(001) to narrow the width distribution of Dy silicide nanowires. This behavior is distinct from the effect of the 7 × 7 reconstruction on the Si(111) surface, where the 7 × 7 serves as a static template and the deposited metal avoids the unit cell boundaries on the substrate. In this case, the 2 × 7 is a dynamic template, and the nanowires nucleate at anti-phase boundaries between 2 × 7 reconstruction domains.

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

Exploration of dysprosium: the most critical element for Japan

NASA Astrophysics Data System (ADS)

Watanabe, Y.

2012-04-01

Dysprosium (Dy), one of the heavy rare earth elements, is used mainly as an additive for NdFeB permanent magnets which are installed in various modern industrial products such as voice coil motors in computers, factory automation machinery, hybrid and electric vehicles, home electronics, and wind turbine, to improve heat resistance of the magnets. Dy has been produced about 2,000t per year from the ores from ion adsorption type deposits in southern China. However, the produced amount of Dy was significantly reduced in 2011 in China due to reservation of heavy rare earth resources and protection of natural environment, resulting in soaring of Dy price in the world. In order to respond the increasing demand of Dy, unconventional supply sources are inevitably developed, in addition to heavy rare earth enriched ion adsorption type deposits outside China. Heavy rare earth elements including Dy are dominantly hosted in xenotime, fergusonite, zircon, eudialyte, keiviite, kainosite, iimoriite, etc. Concentration of xenotime is found in placer deposits in Malaysia and India, hydrothermal deposits associated with unconformity-type uranium mineralization (Athabasca basin in Canada, Western Australia), iron-oxide fluorite mineralization (South Africa) and Sn-bearing alkaline granite (Brazil). Zircon and fergusontie concentration is found as igneous and hydrothermal products in peralkaline syenite, alkaline granite and pegmatite (e.g., Nechalacho in Canada). Eudialyte concentration is found in some peralkaline syenite bodies in Greenland, Canada, Sweden and Russia. Among these sources, large Dy resources are estimated in the deposits hosted in peralkaline rocks (Nechalacho: 79,000t, Kvanefjeld: 49,000t, Norra Karr: 15,700t, etc.) compared to the present demand of Dy. Thus, Dy will be supplied from the deposits associated with peralkaline and alkaline deposits in future instead of ion adsorption type deposits in southern China.

Equation of state of zircon- and scheelite-type dysprosium orthovanadates: a combined experimental and theoretical study.

PubMed

Paszkowicz, Wojciech; Ermakova, Olga; López-Solano, Javier; Mujica, Andrés; Muñoz, Alfonso; Minikayev, Roman; Lathe, Christian; Gierlotka, Stanisław; Nikolaenko, Irina; Dabkowska, Hanna

2014-01-15

Dysprosium orthovanadate, DyVO4, belongs to a family of zircon-type orthovanadates showing a phase transition to scheelite-type structures at moderate pressures below 10 GPa. In the present study, the equations of state (EOSs) for both these phases were determined for the first time using high-pressure x-ray diffraction experiments and ab initio calculations based on the density functional theory. Structural parameters for scheelite-type DyVO4 were calculated from x-ray powder diffraction data as well. The high-pressure experiments were performed under pseudo-hydrostatic conditions at pressures up to 8.44 GPa and 5.5 GPa for the stable zircon-type and metastable (quenched) scheelite-type samples, respectively. Assuming as a compression model the Birch-Murnaghan EOS, we obtained the EOS parameters for both phases. The experimental bulk moduli (K0) for zircon-type and scheelite-type DyVO4 are 118(4) GPa and 153(6) GPa, respectively. Theoretical equations of state were determined by ab initio calculations using the PBE exchange-correlation energy functional of Perdew, Burke, and Ernzerhof. These calculations provide K0 values of 126.1 GPa and 142.9 GPa for zircon-type and scheelite-type DyVO4, respectively. The reliability of the present experimental and theoretical results is supported by (i) the consistency between the values yielded by the two methods (the discrepancy in K0 is as low as about 7% for each of the studied polymorphs) and (ii) their similarity to results obtained under similar compression conditions (hydrostatic or pseudo-hydrostatic) for other rare-earth orthovanadates, such as YVO4 and TbVO4.

China's rare-earth industry

USGS Publications Warehouse

Tse, Pui-Kwan

2011-01-01

Introduction China's dominant position as the producer of over 95 percent of the world output of rare-earth minerals and rapid increases in the consumption of rare earths owing to the emergence of new clean-energy and defense-related technologies, combined with China's decisions to restrict exports of rare earths, have resulted in heightened concerns about the future availability of rare earths. As a result, industrial countries such as Japan, the United States, and countries of the European Union face tighter supplies and higher prices for rare earths. This paper briefly reviews China's rare-earth production, consumption, and reserves and the important policies and regulations regarding the production and trade of rare earths, including recently announced export quotas. The 15 lanthanide elements-lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium (atomic numbers 57-71)-were originally known as the rare earths from their occurrence in oxides mixtures. Recently, some researchers have included two other elements-scandium and yttrium-in their discussion of rare earths. Yttrium (atomic number 39), which lies above lanthanum in transition group III of the periodic table and has a similar 3+ ion with a noble gas core, has both atomic and ionic radii similar in size to those of terbium and dysprosium and is generally found in nature with lanthanides. Scandium (atomic number 21) has a smaller ionic radius than yttrium and the lanthanides, and its chemical behavior is intermediate between that of aluminum and the lanthanides. It is found in nature with the lanthanides and yttrium. Rare earths are used widely in high-technology and clean-energy products because they impart special properties of magnetism, luminescence, and strength. Rare earths are also used in weapon systems to obtain the same properties.

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.

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

Superconducting structure

DOEpatents

Kwon, Chuhee; Jia, Quanxi; Foltyn, Stephen R.

2003-04-01

A superconductive structure including a dielectric oxide substrate, a thin buffer layer of a superconducting material thereon; and, a layer of a rare earth-barium-copper oxide superconducting film thereon the thin layer of yttrium-barium-copper oxide, the rare earth selected from the group consisting of samarium, gadolinium, ytterbium, erbium, neodymium, dysprosium, holmium, lutetium, a combination of more than one element from the rare earth group and a combination of one or more elements from the rare earth group with yttrium, the buffer layer of superconducting material characterized as having chemical and structural compatibility with the dielectric oxide substrate and the rare earth-barium-copper oxide superconducting film is provided.

Superconducting Structure

DOEpatents

Kwon, Chuhee; Jia, Quanxi; Foltyn, Stephen R.

2005-09-13

A superconductive structure including a dielectric oxide substrate, a thin buffer layer of a superconducting material thereon; and, a layer of a rare earth-barium-copper oxide superconducting film thereon the thin layer of yttrium-barium-copper oxide, the rare earth selected from the group consisting of samarium, gadolinium, ytterbium, erbium, neodymium, dysprosium, holmium, lutetium, a combination of more than one element from the rare earth group and a combination of one or more elements from the rare earth group with yttrium, the buffer layer of superconducting material characterized as having chemical and structural compatibility with the dielectric oxide substrate and the rare earth-barium-copper oxide superconducting film is provided.

Ultrasonic effect on the bubble nucleation and heat transfer of oscillating nanofluid

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

Zhao, Nannan; Fu, Benwei; Key Laboratory of Marine, Mechanical and Manufacturing Engineering of the Ministry of Transport, Dalian 116026

Ultrasonic sound effect on bubble nucleation, oscillating motion activated by bubble formation, and its heat transfer enhancement of nanofluid was experimentally investigated. Nanofluid consists of distilled water and dysprosium (III) oxide (Dy{sub 2}O{sub 3}) nanoparticles with an average size of 98 nm and a mass ratio of 0.5%. Visualization results demonstrate that when the nanoparticles are added in the fluid influenced by the ultrasonic sound, bubble nucleation can be significantly enhanced. The oscillating motion initiated by the bubble formation of nanofluid under the influence of ultrasonic sound can significantly enhance heat transfer of nanofluid in an interconnected capillary loop.

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.

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.

Magnetic separation of Dy(III) ions from homogeneous aqueous solutions

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

Pulko, B., E-mail: Barbara.Pulko@tu-dresden.de; Yang, X.; Lei, Z.

2014-12-08

The possibility to enrich paramagnetic dysprosium(III) ions in a magnetic field gradient is proved by means of interferometry, which may open the route for a magnetic separation of rare earth ions from aqueous solutions. The separation dynamics are studied for three different concentrations of DyCl{sub 3} and compared with those found recently in a sulphate solution of the 3d ion Mn(II). In view of the similar-sized hydration spheres for Dy(III) and Mn(II), the slower separation dynamics in DyCl{sub 3} is attributed to both a higher densification coefficient and the strong impact of Brownian motion due to the absence of ion-pairmore » clusters.« less

Does the thermal evolution of molecular structures critically affect the magnetic anisotropy?† †Electronic supplementary information (ESI) available. CCDC 1045631–1045633. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5sc01245g

PubMed Central

Qian, Kang; Baldoví, José J.; Zhang, Yi-Quan; Overgaard, Jacob; Wang, Bing-Wu

2015-01-01

A dysprosium based single-ion magnet is synthesized and characterized by the angular dependence of the single-crystal magnetic susceptibility. Ab initio and effective electrostatic analyses are performed using the molecular structures determined from single crystal X-ray diffraction at 20 K, 100 K and 300 K. Contrary to the common assumption, the results reveal that the structural thermal effects that may affect the energy level scheme and magnetic anisotropy below 100 K are negligible. PMID:29568416

Estimate of contribution of jet aircraft operations to trace element concentration at or near airports

NASA Technical Reports Server (NTRS)

Fordyce, J. S.; Sheibley, D. W.

1974-01-01

Samples of ASTM type A jet fuel were analyzed for trace-element content by instrumental neutron activation techniques. Forty-nine elements were sought. Only ten, aluminum, gold, indium, lanthanum, titanium, vandium, barium, dysprosium, tellurium, and uranium, were observed at levels above the detection limits encountered; of these only aluminum, titanium, and barium were present at concentrations greater than 0.1 ppm. Estimates of exhaust gas concentrations are made, and the ambient contribution at or near airports is calculated by using the Los Angeles International Airport dispersion model. It is shown that the ambient contribution is about an order of magnitude below typical urban levels for virtually all elements sought.

Estimate of contribution of jet aircraft operations to trace element concentration at or near airports

NASA Technical Reports Server (NTRS)

Fordyce, J. S.; Sheibley, D. W.

1975-01-01

Samples of ASTM type A jet fuel were analyzed for trace element content by instrumental neutron activation techniques. Forty-nine elements were sought. Only ten, aluminum, gold, indium, lanthanum, titanium, vanadium, barium, dysprosium, tellurium, and uranium, were observed at levels above the detection limits encountered; of these only aluminum, titanium, and barium were present at concentrations greater than 0.1 ppm. Estimates of exhaust gas concentrations are made, and the ambient contribution at or near airports is calculated by using the Los Angeles International Airport dispersion model. It is shown that the ambient contribution is about an order of magnitude below typical urban levels for virtually all elements sought.

Surface induced selective deposition of Dysprosium Polyoxometalate on HOPG surface studied by STM and STS

NASA Astrophysics Data System (ADS)

Costa Milan, David; Pinilla Cienfuegos, Elena; Cardona Serra, Salvador; Coronado Miralles, Eugenio; Untiedt Lecuona, Carlos

2013-03-01

Scanning Tunneling Microscope (STM) and scanning Tunnelling spectroscopy (STS) techniques have been used to study the Preyssler type Polyoxometalate K12[DyP5W30O110] molecules deposited on Highly Oriented Pyrolytic Graphite surface (HOPG). Chainlike arrangements of clusters containing two or three molecules, as well as different cluster sizes are observed. As many structural artifacts are present on the graphite surface, like Moiré patterns, that could look like the molecular deposits, we have studied their STS and size to ensure the presence of the POM molecules on the surface. This article shows the possibility of addressing POMs on a flat surface to obtain their electronic properties through STS.

Semiempirical Quantum Chemistry Model for the Lanthanides: RM1 (Recife Model 1) Parameters for Dysprosium, Holmium and Erbium

PubMed Central

Filho, Manoel A. M.; Dutra, José Diogo L.; Rocha, Gerd B.; Simas, Alfredo M.; Freire, Ricardo O.

2014-01-01

Complexes of dysprosium, holmium, and erbium find many applications as single-molecule magnets, as contrast agents for magnetic resonance imaging, as anti-cancer agents, in optical telecommunications, etc. Therefore, the development of tools that can be proven helpful to complex design is presently an active area of research. In this article, we advance a major improvement to the semiempirical description of lanthanide complexes: the Recife Model 1, RM1, model for the lanthanides, parameterized for the trications of Dy, Ho, and Er. By representing such lanthanide in the RM1 calculation as a three-electron atom with a set of 5 d, 6 s, and 6 p semiempirical orbitals, the accuracy of the previous sparkle models, mainly concentrated on lanthanide-oxygen and lanthanide-nitrogen distances, is extended to other types of bonds in the trication complexes’ coordination polyhedra, such as lanthanide-carbon, lanthanide-chlorine, etc. This is even more important as, for example, lanthanide-carbon atom distances in the coordination polyhedra of the complexes comprise about 30% of all distances for all complexes of Dy, Ho, and Er considered. Our results indicate that the average unsigned mean error for the lanthanide-carbon distances dropped from an average of 0.30 Å, for the sparkle models, to 0.04 Å for the RM1 model for the lanthanides; for a total of 509 such distances for the set of all Dy, Ho, and Er complexes considered. A similar behavior took place for the other distances as well, such as lanthanide-chlorine, lanthanide-bromine, lanthanide, phosphorus and lanthanide-sulfur. Thus, the RM1 model for the lanthanides, being advanced in this article, broadens the range of application of semiempirical models to lanthanide complexes by including comprehensively many other types of bonds not adequately described by the previous models. PMID:24497945

Experimental and theoretical approach on the optical properties of zinc borotellurite glass doped with dysprosium oxide

NASA Astrophysics Data System (ADS)

Halimah, M. K.; Ami Hazlin, M. N.; Muhammad, F. D.

2018-04-01

A series of glass samples with chemical formula {[(TeO2)0.7(B2O3)0.3]0.7(ZnO)0.3}1 - x(Dy2O3)x where x = 0.01, 0.02, 0.03, 0.04 and 0.05 M fraction were synthesized through conventional melt-quenching method. The most common way to fabricate a glass material is by fusion of two or more component oxides followed by their quenching. This technique is known as melt-quenching technique. Kaur et al. (2016) [1] highlighted that the melt-quenching method able to enhance the mechanical properties like hardness and flexural strength of the material. The nature of the glass systems is proven to be amorphous based on the XRD pattern. The FTIR spectra of the glass systems confirm the existence of five bands which are assigned for the BO4, BO3, TeO4 and TeO3 vibrational groups. The density of the glass systems is increased with the addition of Dy2O3 while the molar volume is found to be inversely proportional to the density of the proposed glass. The optical properties of the glasses are determined through the absorption spectra obtained from the UV-VIS spectrophotometer. From the absorption spectra, the indirect and direct optical band gaps and the Urbach energy are found to be inversely proportional to each other. As the molar fraction of the Dy2O3 increased, the optical band gaps are observed to increase as opposed to the Urbach energy. For this glass system, the values of refractive index, electronic polarizability, oxide ion polarizability and the optical basicity are found to decrease as the addition of the dysprosium oxide is increased. From the emission spectra, two intense blue and yellow emission bands are observed, which correspond to the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions of Dy3 + ions respectively. The CIE chromaticity coordinates of the zinc borotellurite glass systems are found to be located in the white light region. Generation of white light The generation of the white light can be achieved by using two emission bands which comprise of the yellow and blue emission. The white light emission of the glass systems is confirmed by using the Commission International de I'Eclairage 1931 (CIE 1931) chromaticity diagram. The colour coordinate of the zinc borotellurite glass systems doped Dy2O3 is tabulated in Table 3 while Fig. 10 represents the colour chromaticity diagram of Dy2O3 doped zinc borotellurite glass systems. Based on the result obtained, the CIE coordinate for the zinc borotellurite glass doped with dysprosium oxide lies closed to the standard white light point which located at x = 0.333 and y = 0.333 [63,64]. This suggests that the zinc borotellurite glass doped with Dy2O3 may be useful for the solid state lighting application.

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.

Rare earth elements: end use and recyclability

USGS Publications Warehouse

Goonan, Thomas G.

2011-01-01

Rare earth elements are used in mature markets (such as catalysts, glassmaking, lighting, and metallurgy), which account for 59 percent of the total worldwide consumption of rare earth elements, and in newer, high-growth markets (such as battery alloys, ceramics, and permanent magnets), which account for 41 percent of the total worldwide consumption of rare earth elements. In mature market segments, lanthanum and cerium constitute about 80 percent of rare earth elements used, and in new market segments, dysprosium, neodymium, and praseodymium account for about 85 percent of rare earth elements used. Regardless of the end use, rare earth elements are not recycled in large quantities, but could be if recycling became mandated or very high prices of rare earth elements made recycling feasible.

Magnetic Nanofluid Rare Earth Element Extraction Process Report, Techno Economic Analysis, and Results for Geothermal Fluids

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

Pete McGrail

This GDR submission is an interim technical report and raw data files from the first year of testing on functionalized nanoparticles for rare earth element extraction from geothermal fluids. The report contains Rare Earth Element uptake results (percent removal, mg Rare Earth Element/gram of sorbent, distribution coefficient) for the elements of Neodymium, Europium, Yttrium, Dysprosium, and Cesium. A detailed techno economic analysis is also presented in the report for a scaled up geothermal rare earth element extraction process. All rare earth element uptake testing was done on simulated geothermal brines with one rare earth element in each brine. The raremore » earth element uptake testing was conducted at room temperature.« less

STABILIZED RARE EARTH OXIDES FOR A CONTROL ROD AND METHOD OF PREPARATION

DOEpatents

McNees, R.A.; Potter, R.A.

1964-01-14

A method is given for preparing mixed oxides of the formula MR/sub x/O/ sub 12/ wherein M is tungsten or molybdenum and R is a rare earth in the group consisting of samarium, europium, dysprosium, and gadolinium and x is 4 to 5. Oxides of this formula, and particularly the europiumcontaining species, are useful as control rod material for water-cooled nuclear reactors owing to their stability, favorable nuclear properties, and resistance to hydration. These oxides may be utilized as a dispersion in a stainlesssteel matrix. Preparation of these oxides is effected by blending tungsten oxide or molybdenum oxide with a rare earth oxide, compressing the mixture, and firing at an elevated temperature in an oxygen-containing atmosphere. (AEC)

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

Development of Improved Burnable Poisons for Commercial Nuclear Power Reactors

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

Renier, J.A.

2002-04-17

Burnable poisons are used in all modern nuclear reactors to permit higher loading of fuel without the necessity of an overly large control rod system. This not only permits a longer core life but can also be used to level the power distribution. Commercial nuclear reactors commonly use B{sub 4}C in separate non-fueled rods and more recently, zirconium boride coatings on the fuel pellets or gadolinium oxide mixed with the fuel. Although the advantages are great, there are problems with using these materials. Boron, which is an effective neutron absorber, transmutes to lithium and helium upon absorption of a neutron.more » Helium is insoluble and is eventually released to the interior of the fuel rod, where it produces an internal pressure. When sufficiently high, this pressure stress could cause separation of the cladding from the fuel, causing overly high centerline temperatures. Gadolinium has several very strongly absorbing isotopes, but not all have large cross sections and result in residual burnable poison reactivity worth at the end of the fuel life. Even if the amount of this residual absorber is small and the penalty in operation small, the cost of this penalty, even if only several days, can be very high. The objective of this investigation was to study the performance of single isotopes in order to reduce the residual negative reactivity left over at the end of the fuel cycle. Since the behavior of burnable poisons can be strongly influenced by their configuration, four forms for the absorbers were studied: homogeneously mixed with the fuel, mixed with only the outer one-third of the fuel pellet, coated on the perimeter of the fuel pellets, and alloyed with the cladding. In addition, the numbers of fuel rods containing burnable poison were chosen as 8, 16, 64, and 104. Other configurations were chosen for a few special cases. An enrichment of 4.5 wt% {sup 235}U was chosen for most cases for study in order to achieve a 4-year fuel cycle. A standard pressurized water reactor fuel core was chosen for the study, and state-of-the-art neutronic reactor core computer codes were used for analysis. Power distribution, fuel burnup, reactivity due to burnable poisons and other fission products, spectrum shift, core reactivity, moderator void coefficients, as well as other parameters were calculated as a function of time and fuel burnup. The results not only showed advantages of separation of burnable poison isotopes but revealed benefits to be achieved by careful selection of the configuration of even naturally occurring elements used as burnable poisons. The savings in terms of additional days of operation is shown in Figure 1, where the savings is plotted for each of six favorable isotopes in the four configurations. The benefit of isotope separation is most dramatic for dysprosium, but even the time savings in the case of gadolinium is several days. For a modern nuclear plant, one day's worth of electricity is worth about one million dollars, so the resulting savings of only a few days is considerable. It is also apparent that the amount of savings depends upon the configuration of the burnable poison.« less

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.

Scissors Mode of Dipolar Quantum Droplets of Dysprosium Atoms

NASA Astrophysics Data System (ADS)

Ferrier-Barbut, Igor; Wenzel, Matthias; Böttcher, Fabian; Langen, Tim; Isoard, Mathieu; Stringari, Sandro; Pfau, Tilman

2018-04-01

We report on the observation of the scissors mode of a single dipolar quantum droplet. The existence of this mode is due to the breaking of the rotational symmetry by the dipole-dipole interaction, which is fixed along an external homogeneous magnetic field. By modulating the orientation of this magnetic field, we introduce a new spectroscopic technique for studying dipolar quantum droplets. This provides a precise probe for interactions in the system, allowing us to extract a background scattering length for 164Dy of 69 (4 )a0 . Our results establish an analogy between quantum droplets and atomic nuclei, where the existence of the scissors mode is also only due to internal interactions. They further open the possibility to explore physics beyond the available theoretical models for strongly dipolar quantum gases.

Sequential Dy(OTf)3 -Catalyzed Solvent-Free Per-O-Acetylation and Regioselective Anomeric De-O-Acetylation of Carbohydrates.

PubMed

Yan, Yi-Ling; Guo, Jiun-Rung; Liang, Chien-Fu

2017-09-19

Dysprosium(III) trifluoromethanesulfonate-catalyzed per-O-acetylation and regioselective anomeric de-O-acetylation of carbohydrates can be tuned by adjusting the reaction medium. In this study, the per-O-acetylation of unprotected sugars by using a near-stoichiometric amount of acetic anhydride under solvent-free conditions resulted in the exclusive formation of acetylated saccharides as anomeric mixtures, whereas anomeric de-O-acetylation in methanol resulted in a moderate-to-excellent yield. Reactions with various unprotected monosaccharides or disaccharides followed by a semi-one-pot sequential conversion into the corresponding acetylated glycosyl hemiacetal also resulted in high yields. Furthermore, the obtained hemiacetals could be successfully transformed into trichloroimidates after Dy(OTf) 3 -catalyzed glycosylation. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Biological fabrication of cellulose fibers with tailored properties

NASA Astrophysics Data System (ADS)

Natalio, Filipe; Fuchs, Regina; Cohen, Sidney R.; Leitus, Gregory; Fritz-Popovski, Gerhard; Paris, Oskar; Kappl, Michael; Butt, Hans-Jürgen

2017-09-01

Cotton is a promising basis for wearable smart textiles. Current approaches that rely on fiber coatings suffer from function loss during wear. We present an approach that allows biological incorporation of exogenous molecules into cotton fibers to tailor the material’s functionality. In vitro model cultures of upland cotton (Gossypium hirsutum) are incubated with 6-carboxyfluorescein-glucose and dysprosium-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid-glucose, where the glucose moiety acts as a carrier capable of traveling from the vascular connection to the outermost cell layer of the ovule epidermis, becoming incorporated into the cellulose fibers. This yields fibers with unnatural properties such as fluorescence or magnetism. Combining biological systems with the appropriate molecular design offers numerous possibilities to grow functional composite materials and implements a material-farming concept.

Optical properties of Dy3+ doped YBO3 phosphor

NASA Astrophysics Data System (ADS)

Nair, Ramya G.; Nigam, Sandeep; Sudarsan, V.; Vatsa, R. K.

2018-04-01

Dysprosium doped YBO3 luminescent particleis synthesized via poly-ol method and by subsequent annealing at 800°C. The synthesized material has been characterized for structure properties using powder X-ray diffraction (XRD) and Fourier transform infrared (FTIR)spectroscopy. Photoluminescence properties of these samples are studiedby means of steady state measurements and decay curve. The phosphor shows characteristic transitions of Dy3+ in the excitation and emission spectra. Colour purity is determined in terms of yellow/blue ratio, which is found to be 1.8. The higher ratio of yellow/blue indicates that Dy3+ preferentially occupies the asymmetric site in host lattice. The average lifetime is found to be 1.1ms. The chromatic properties of the phosphor have been found to have chromaticity coordinates x = 0.245, y = 0.274.

The AMBRE Project: r-process element abundances in the Milky Way thin and thick discs

NASA Astrophysics Data System (ADS)

Guiglion, Guillaume; de Laverny, Patrick; Recio-Blanco, Alejandra; Worley, C. Clare

2018-04-01

Chemical evolution of r-process elements in the Milky Way disc is still a matter of debate. We took advantage of high resolution HARPS spectra from the ESO archive in order to derive precise chemical abundances of 3 r-process elements Eu, Dy & Gd for a sample of 4 355 FGK Milky Way stars. The chemical analysis has been performed thanks to the automatic optimization pipeline GAUGUIN. Based on the [α/Fe] ratio, we chemically characterized the thin and the thick discs, and present here results of these 3 r-process element abundances in both discs. We found an unexpected Gadolinium and Dysprosium enrichment in the thick disc stars compared to Europium, while these three elements track well each other in the thin disc.

Visible luminescence of dysprosium ions in oxyhalide lead borate glasses.

PubMed

Pisarska, Joanna; Żur, Lidia; Pisarski, Wojciech A

2011-08-15

Visible luminescence of Dy(3+) ions in oxyhalide lead borate glasses was examined. Luminescence spectra show two intense bands at 480 nm and 573 nm due to (4)F(9/2)→(6)H(15/2) (blue) and (4)F(9/2)→(6)H(13/2) (yellow) transitions of Dy(3+). Luminescence decays from (4)F(9/2) state and yellow-to-blue luminescence intensity ratios (Y/B) were analysed with PbX(2) (X=F, Cl) content. An introduction of PbX(2) to the borate glass results in the increasing of (4)F(9/2) lifetime and the decreasing of yellow-to-blue luminescence intensity ratio, which is due to reduction of covalency between Dy(3+) and O(2-)/X(-) ions. Copyright © 2010 Elsevier B.V. All rights reserved.

Effect of dysprosium and lutetium metal buffer layers on the resistive switching characteristics of Cu-Sn alloy-based conductive-bridge random access memory.

PubMed

Vishwanath, Sujaya Kumar; Woo, Hyunsuk; Jeon, Sanghun

2018-06-18

Conductive-bridge random access memory (CBRAM) has become one of the most suitable candidates for non-volatile memory in next-generation information and communication technology. The resistive switching mechanism of CBRAM depends on the formation/annihilation of the conductive filament (CF) between the active metal electrode and the inert electrode. However, excessive ion injection from the active electrode into the solid electrolyte is reduces the uniformity and reliability of the resistive switching devices. To solve this problem, we investigated the resistive switching characteristics of a modified active electrode with different compositions of Cu_x-Sn_{_1-x}(0.13 < X < 0.55). The resistive switching characteristics were further improved by inserting a dysprosium (Dy) or lutetium (Lu) buffer layer at the interface of Cu_x-Sn_1-x/Al₂O₃. Electrical analysis of the optimal Cu_0.27-Sn_0.73/Lu-based CBRAM exhibited stable resistive switching behavior with low operation voltage (SET: 0.7 V and RESET: -0.3 V), a high on/off resistive ratio (10⁶), cyclic endurance (>10⁴), and long-term retention (85℃/10 years). To achieve these performance parameters, CFs were locally formed inside the electrolyte using a modified CuSn active electrode, and the amount of Cu-ion injection was reduced by inserting the Dy or Lu buffer layer between the CuSn active electrode and the electrolyte. In particular, conductive-atomic force microscopy results at the Dy/ or Lu/Al₂O₃ interface directly showed and defined the diameter of the CF. © 2018 IOP Publishing Ltd.

Antimony-ligated dysprosium single-molecule magnets as catalysts for stibine dehydrocoupling† †Electronic supplementary information (ESI) available: Synthetic details, spectroscopic characterization for all compounds, X-ray crystallography details and crystallographic information files, computational details. CCDC 1484570–1484573 and 1485316. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c6sc04465d Click here for additional data file. Click here for additional data file.

PubMed Central

Pugh, Thomas

2017-01-01

Single-molecule magnets (SMMs) are coordination compounds that exhibit magnetic bistability below a characteristic blocking temperature. Research in this field continues to evolve from its fundamental foundations towards applications of SMMs in information storage and spintronic devices. Synthetic chemistry plays a crucial role in targeting the properties that could ultimately produce SMMs with technological potential. The ligands in SMMs are invariably based on non-metals; we now report a series of dysprosium SMMs (in addition to their magnetically dilute analogues embedded in yttrium matrices) that contain ligands with the metalloid element antimony as the donor atom, i.e. [(η5-Cp′2Dy){μ-Sb(H)Mes}]3 (1-Dy) and [(η5-Cp′2Dy)3{μ-(SbMes)3Sb}] (2-Dy), which contain the stibinide ligand [Mes(H)Sb]– and the unusual Zintl-like ligand [Sb4Mes3]3–, respectively (Cp′ = methylcyclopentadienyl; Mes = mesityl). The zero-field anisotropy barriers in 1-Dy and 2-Dy are U eff = 345 cm–1 and 270 cm–1, respectively. Stabilization of the antimony-ligated SMMs is contingent upon careful control of reaction time and temperature. With longer reaction times and higher temperatures, the stibine pro-ligands are catalytically dehydrocoupled by the rare-earth precursor complexes. NMR spectroscopic studies of the yttrium-catalysed dehydrocoupling reactions reveal that 1-Y and 2-Y are formed during the catalytic cycle. By implication, 1-Dy and 2-Dy should also be catalytic intermediates, hence the nature of these complexes as SMMs in the solid-state and as catalysts in solution introduces a strategy whereby new molecular magnets can be identified by intercepting species formed during catalytic reactions. PMID:28451326

Application of 1H and 23Na magic angle spinning NMR spectroscopy to define the HRBC up-taking of MRI contrast agents

NASA Astrophysics Data System (ADS)

Calabi, Luisella; Paleari, Lino; Biondi, Luca; Linati, Laura; De Miranda, Mario; Ghelli, Stefano

2003-09-01

The up-take of Gd(III) complexes of BOPTA, DTPA, DOTA, EDTP, HPDO3A, and DOTP in HRBC has been evaluated by measuring the lanthanide induced shift (LIS) produced by the corresponding dysprosium complexes (DC) on the MAS-NMR resonances of water protons and free sodium ions. These complexes are important in their use as MRI contrast agents (MRI-CA) in diagnostics. 1H and 23Na MAS-NMR spectra of HRBC suspension, collected at 9.395 T, show only one signal due to extra- and intra-cellular water (or sodium). In MAS spectra, the presence of DC in a cellular compartment produces the LIS of only the nuclei (water proton or sodium) in that cellular compartment and this LIS can be related to the DC concentrations (by the experimental curves of LIS vs. DC concentrations) collected in the physiological solution. To obtain correct results about LIS, the use of MAS technique is mandatory, because it guarantees the only the nuclei staying in the same cellular compartment where the LC is present show the LIS. In all the cases considered, the addition of the DC to HRBC (100% hematocrit) produced a shift of only the extra-cellular water (or sodium) signal and the gradient of concentration ( GC) between extra- and intra-cellular compartments resulted greater than 100:1, when calculated by means of sodium signals. These high values of GC are direct proofs that none of the tested dysprosium complexes crosses the HRBC membrane. Since the DC are iso-structural to the gadolinium complexes the corresponding gadolinium ones (MRI-CA) do not cross the HRBC membrane and, consequently, they are not up-taken in HRBC. The GC values calculated by means of water proton signals resulted much lower than those obtained by sodium signals. This proves that the choice of the isotope is a crucial step in order to use this method in the best way. In fact, GC value depends on the lowest detectable LIS which, in turn, depends on the nature of the LC (lanthanide complex) and the observed isotopes.

Experimental and theoretical approach on the optical properties of zinc borotellurite glass doped with dysprosium oxide.

PubMed

Halimah, M K; Ami Hazlin, M N; Muhammad, F D

2018-04-15

A series of glass samples with chemical formula {[(TeO 2 ) 0.7 (B 2 O 3 ) 0.3 ] 0.7 (ZnO) 0.3 } 1-x (Dy 2 O 3 ) x where x=0.01, 0.02, 0.03, 0.04 and 0.05M fraction were synthesized through conventional melt-quenching method. The most common way to fabricate a glass material is by fusion of two or more component oxides followed by their quenching. This technique is known as melt-quenching technique. Kaur et al. (2016) [1] highlighted that the melt-quenching method able to enhance the mechanical properties like hardness and flexural strength of the material. The nature of the glass systems is proven to be amorphous based on the XRD pattern. The FTIR spectra of the glass systems confirm the existence of five bands which are assigned for the BO 4 , BO 3, TeO 4 and TeO 3 vibrational groups. The density of the glass systems is increased with the addition of Dy 2 O 3 while the molar volume is found to be inversely proportional to the density of the proposed glass. The optical properties of the glasses are determined through the absorption spectra obtained from the UV-VIS spectrophotometer. From the absorption spectra, the indirect and direct optical band gaps and the Urbach energy are found to be inversely proportional to each other. As the molar fraction of the Dy 2 O 3 increased, the optical band gaps are observed to increase as opposed to the Urbach energy. For this glass system, the values of refractive index, electronic polarizability, oxide ion polarizability and the optical basicity are found to decrease as the addition of the dysprosium oxide is increased. From the emission spectra, two intense blue and yellow emission bands are observed, which correspond to the 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 transitions of Dy 3+ ions respectively. The CIE chromaticity coordinates of the zinc borotellurite glass systems are found to be located in the white light region. Copyright © 2017 Elsevier B.V. All rights reserved.

Longitudinal residual stresses in boron fibers

NASA Technical Reports Server (NTRS)

Behrendt, D. R.

1976-01-01

A method of measuring the longitudinal residual stress distribution in boron fibers is presented. The residual stresses in commercial CVD boron on tungsten fibers of 102, 142, and 203 microns (4, 5.6, and 8 mil) diameters were determined. Results for the three sizes show a compressive stress at the surface 800 to -1400 MN/sq m 120 to -200 ksi), changing monotonically to a region of tensile stress within the boron. At approximately 25 percent of the original radius, the stress reaches a maximum tensile 600 to 1000 MN/sq m(90 to 150 ksi) and then decreases to compressive near the tungsten boride core. The core itself is under a compressive stress of approximately -1300 MN/sq m (-190 ksi). The effects of surface removal on core residual stress and core-initiated fracture are discussed.

High-pressure, high-temperature synthesis of superhard boron suboxide

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

Hubert, H.; Garvie, L.A.J.; Leinenweber, K.

A multianvil device was used to investigate the formation of B{sub x}O phases produced in the 2 to 10 GPa pressure range with temperatures between 1,000 and 1,800 C. Amorphous and crystalline B and BP were oxidized using B{sub 2}O{sub 3} and CrO{sub 3}. Using powder X-ray diffraction and parallel electron energy-loss spectroscopy (PEELS), the authors were unable to detect graphitic or diamond-structured B{sub 2}O, reported in previous studies. The refractory boride B{sub 6}O, which has the {alpha}-rhombohedral boron structure, is the dominant suboxide in the P and T range of the investigation. PEELS with a transmission electron microscope wasmore » used to characterize the boron oxides.« less

Combustion synthesis of boride and other composites

DOEpatents

Halverson, D.C.; Lum, B.Y.; Munir, Z.A.

1988-07-28

A self-sustaining combustion synthesis process for producing hard, tough, lightweight B/sub 4/C/TiB/sub 2/ composites is described. It 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. 9 figs., 4 tabs.

Oxidation-induced contraction and strengthening of boron fibers

NASA Technical Reports Server (NTRS)

Dicarlo, J. A.; Wagner, T. C.

1981-01-01

An investigation of the physical and mechanical effects of thermal treatment in a controlled oxygen-argon atmosphere on boron fibers is reported, with attention to the optimization of such treatment as a secondary processing method for improvement of fiber strength. The strengthening mechanism is comprised of an oxidation-induced axial contraction of the fiber, accompanied by axial compression of strength-limiting flaws within the fiber's tungsten boride core. It was found that after an oxidation contraction of 0.3% near 900 C, and a slight surface etch near 100 C, the average tensile strength of 203-micron fibers increased from 500 to 800 ksi. Various physical observations are used to develop mechanistic models of oxidation, contraction, and the formation of new flaws in the boron sheath at contractions greater than 0.3%.

Direct synthesis of calcium borohydride

DOEpatents

Ronnebro, Ewa Carin Ellinor [Dublin, CA; Majzoub, Eric H [Pleasanton, CA

2009-10-27

A method is disclosed for directly preparing an alkaline earth metal borohydride, i.e. Ca(BH.sub.4).sub.2, from the alkaline earth metal hydride and the alkaline earth metal boride. The borohydride thus prepared is doped with a small portion of a metal chloride catalyst compound, such as RuCl.sub.3, TiCl.sub.3, or a mixture of TiCl.sub.3 and palladium metal. The process provides for mechanically mixing the dry reagents under an inert atmosphere followed by charging the mixed materials with high pressure hydrogen at about 70 MPa while heating the mixture to about 400.degree. C. The method is relatively simple and inexpensive and provides reversible hydride compounds which are free of the usual contamination introduced by prior art wet chemical methods.

(Pt{sub 1–x}Cu{sub x}){sub 3}Cu{sub 2}B and Pt{sub 9}Cu{sub 3}B{sub 5}, the first examples of copper platinum borides. Observation of superconductivity in a novel boron filled β-Mn-type compound

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

Salamakha, Leonid P.; Sologub, Oksana, E-mail: oksana.sologub@univie.ac.at; Stöger, Berthold

New ternary copper platinum borides have been synthesized by arc melting of pure elements followed by annealing at 600 °C. The structures have been studied by X-ray single crystal and powder diffraction. (Pt{sub 1−x}Cu{sub x}){sub 3}Cu{sub 2}B (x=0.33) forms a B-filled β-Mn-type structure (space group P4{sub 1}32; a=0.6671(1) nm). Cu atoms are distributed preferentially on the 8c atom sites, whereas the 12d site is randomly occupied by Pt and Cu atoms (0.670(4) Pt±0.330(4) Cu). Boron is located in octahedral voids of the parent β-Mn-type structure. Pt{sub 9}Cu{sub 3}B{sub 5} (space group P-62m; a=0.9048(3) nm, c=0.2908(1) nm) adopts the Pt{sub 9}Zn{submore » 3}B{sub 5–δ}-type structure. It has a columnar architecture along the short translation vector exhibiting three kinds of [Pt{sub 6}] trigonal prism columns (boron filled, boron semi-filled and empty) and Pt channels with a pentagonal cross section filled with Cu atoms. The striking structural feature is a [Pt{sub 6}] cluster in form of an empty trigonal prism at the origin of the unit cell, which is surrounded by coupled [BPt{sub 6}] and [Pt{sub 6}] trigonal prisms, rotated perpendicularly to the central one. There is no B–B contact as well as Cu–B contact in the structure. The relationships of Pt{sub 9}Cu{sub 3}B{sub 5} structure with the structure of Ti{sub 1+x}Os{sub 2−x}RuB{sub 2} as well as with the structure families of metal sulfides and aluminides have been elucidated. (Pt{sub 1–x}Cu{sub x}){sub 3}Cu{sub 2}B (x=0.3) (B-filled β-Mn-type structure) is a bulk superconductor with a transition temperature of about 2.06 K and an upper critical field μ{sub 0}H{sub C2}(0){sup WHH} of 1.2 T, whereas no superconducting transition has been observed up to 0.3 K in Pt{sub 9}Cu{sub 3}B{sub 5} (Pt{sub 9}Zn{sub 3}B{sub 5–δ}-type structure) from electrical resistivity measurements. - Highlights: • First two copper platinum borides, (Pt{sub 0.67}Cu{sub 0.33}){sub 3}Cu{sub 2}B and Pt{sub 9}Cu{sub 3}B{sub 5} were obtained. • (Pt{sub 0.67}Cu{sub 0.33}){sub 3}Cu{sub 2}B forms a B-filled β-Mn-type structure. • Pt{sub 9}Cu{sub 3}B{sub 5} adopts a Pt{sub 9}Zn{sub 3}B{sub 5–δ}-type structure. • Boron atoms exhibit octahedral and trigonal prismatic coordination. • (Pt{sub 1–x}Cu{sub x})3Cu{sub 2}B (x=0.3) is a bulk superconductor with T{sub c} 2.06 K.« less

White- and blue-light-emitting dysprosium(III) and terbium(III)-doped gadolinium titanate phosphors.

PubMed

Antić, Ž; Kuzman, S; Đorđević, V; Dramićanin, M D; Thundat, T

2017-06-01

Here we report the synthesis and structural, morphological, and photoluminescence analysis of white- and blue-light-emitting Dy 3 + - and Tm 3 + -doped Gd 2 Ti 2 O 7 nanophosphors. Single-phase cubic Gd 2 Ti 2 O 7 nanopowders consist of compact, dense aggregates of nanoparticles with an average size of ~25 nm for Dy 3 + -doped and ~50 nm for Tm 3 + -doped samples. The photoluminescence results indicated that ultraviolet (UV) light excitation of the Dy 3 + -doped sample resulted in direct generation of white light, while a dominant yellow emission was obtained under blue-light excitation. Intense blue light was obtained for Tm 3 + -doped Gd 2 Ti 2 O 7 under UV excitation suggesting that this material could be used as a blue phosphor. Copyright © 2016 John Wiley & Sons, Ltd.

Radiological Hazard of Spallation Products in Accelerator-Driven System

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

Saito, M.; Stankovskii, A.; Artisyuk, V.

The central issue underlying this paper is related to elucidating the hazard of radioactive spallation products that might be an important factor affecting the design option of accelerator-driven systems (ADSs). Hazard analysis based on the concept of Annual Limit on Intake identifies alpha-emitting isotopes of rare earths (REs) (dysprosium, gadolinium, and samarium) as the dominant contributors to the overall toxicity of traditional (W, Pb, Pb-Bi) targets. The matter is addressed from several points of view: code validation to simulate their yields, choice of material for the neutron producing targets, and challenging the beam type. The paper quantitatively determines the domainmore » in which the toxicity of REs exceeds that of polonium activation products broadly discussed now in connection with advertising lead-bismuth technology for the needs of ADSs.« less

Effect of temperature and rare-earth doping on charge-carrier mobility in indium-monoselenide crystals

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

Abdinov, A. Sh., E-mail: abdinov-axmed@yandex.ru; Babayeva, R. F., E-mail: Babaeva-Rena@yandex.ru; Amirova, S. I.

2013-08-15

In the temperature range T = 77-600 K, the dependence of the charge-carrier mobility ({mu}) on the initial dark resistivity is experimentally investigated at 77 K ({rho}d{sub 0}), as well as on the temperature and the level (N) of rare-earth doping with such elements as gadolinium (Gd), holmium (Ho), and dysprosium (Dy) in n-type indium-monoselenide (InSe) crystals. It is established that the anomalous behavior of the dependences {mu}(T), {mu}({rho}d{sub 0}), and {mu}(N) found from the viewpoint of the theory of charge-carrier mobility in crystalline semiconductors is related, first of all, to partial disorder in indium-monoselenide crystals and can be attributedmore » to the presence of random drift barriers in the free energy bands.« less

Silicon rich nitride ring resonators for rare - earth doped telecommunications-band amplifiers pumped at the O-band.

PubMed

Xing, P; Chen, G F R; Zhao, X; Ng, D K T; Tan, M C; Tan, D T H

2017-08-22

Ring resonators on silicon rich nitride for potential use as rare-earth doped amplifiers pumped at 1310 nm with amplification at telecommunications-band are designed and characterized. The ring resonators are fabricated on 300 nm and 400 nm silicon rich nitride films and characterized at both 1310 nm and 1550 nm. We demonstrate ring resonators exhibiting similar quality factors exceeding 10,000 simultaneously at 1310 nm and 1550 nm. A Dysprosium-Erbium material system exhibiting photoluminescence at 1510 nm when pumped at 1310 nm is experimentally demonstrated. When used together with Dy-Er co-doped particles, these resonators with similar quality factors at 1310 nm and 1550 nm may be used for O-band pumped amplifiers for the telecommunications-band.

Thermoluminescence (TL) dosimeter of dysprosium doped strontium borate glass for different glass modifiers (Na, Li, Ca) subjected from 1 to 9 Gy doses

NASA Astrophysics Data System (ADS)

Hamzah, S. A.; Saeed, M. A.; Wagiran, H.; Hashim, I. H.

2017-10-01

This article reports TL response for different glass modifier and doping concentration. Alkali oxides (Na2O and Li2O) and alkali earth oxide (CaO) will be used as a glass modifier for strontium borate based glass. The samples were prepared by melt quenching technique. Dy2O3 concentrations ranging from 0.00 to 0.70 mol% and exposure doses of 1 to 9 Gy will be varied. All glass samples exhibit the prominent peak temperature positioned at 186 oC to 232 oC. From all the samples, one of the samples shows an excellent linearity dose response, higher TL and show good reproducibility after 5 cycles exposure which is sodium strontium borate doped with 0.1 mol% Dy2O3 (optimum concentration).

New high boron content polyborane precursors to advanced ceramic materials: New syntheses, new applications

NASA Astrophysics Data System (ADS)

Guron, Marta

There is a need for new synthetic routes to high boron content materials for applications as polymeric precursors to ceramics, as well as in neutron shielding and potential medical applications. To this end, new ruthenium-catalyzed olefin metathesis routes have been devised to form new complex polyboranes and polymeric species. Metathesis of di-alkenyl substituted o-carboranes allowed the synthesis of ring-closed products fused to the carborane cage, many of which are new compounds and one that offers a superior synthetic method to one previously published. Acyclic diene metathesis of di-alkenyl substituted m-carboranes resulted in the formation of new main-chain carborane-containing polymers of modest molecular weights. Due to their extremely low char yields, and in order to explore other metathesis routes, ring opening metathesis polymerization (ROMP) was used to generate the first examples of poly(norbornenyl- o-carboranes). Monomer synthesis was achieved via a two-step process, incorporating Ti-catalyzed hydroboration to make 6-(5-norbornenyl)-decaborane, followed by alkyne insertion in ionic liquid media to achieve 1,2-R2 -3-norbornenyl o-carborane species. The monomers were then polymerized using ROMP to afford several examples of poly(norbornenyl- o-carboranes) with relatively high molecular weights. One such polymer, [1-Ph, 3-(=CH2-C5H7-CH2=)-1,2-C 2B10H10]n, had a char yield very close to the theoretical char yield of 44%. Upon random copolymerization with poly(6-(5-norbornenyl) decaborane), char yields significantly increased to 80%, but this number was well above the theoretical value implicating the formation of a boron-carbide/carbon ceramic. Finally, applications of polyboranes were explored via polymer blends toward the synthesis of ceramic composites and the use of polymer precursors as reagents for potential ultra high temperature ceramic applications. Upon pyrolysis, polymer blends of poly(6-(5-norbornenyl)-decaborane) and poly(methylcarbosilane) converted into boron-carbide/silicon-carbide ceramics with high char yields. These polymer blends were also shown to be useful as reagents for synthesis of hafnium-boride/hafnium-carbide/silicon carbide and zirconium-boride/zirconium-carbide/silicon carbide composites.

New examples of ternary rare-earth metal boride carbides containing finite boron carbon chains: The crystal and electronic structure of RE15B6C20 (RE=Pr, Nd)

NASA Astrophysics Data System (ADS)

Babizhetskyy, Volodymyr; Mattausch, Hansjürgen; Simon, Arndt; Hiebl, Kurt; Ben Yahia, Mouna; Gautier, Régis; Halet, Jean-François

2008-08-01

The ternary rare-earth metal boride carbides RE15B6C20 (RE=Pr, Nd) were synthesized by co-melting the elements. They exist above 1270 K. Their crystal structures were determined from single-crystal X-ray diffraction data. Both crystallize in the space group P1¯, Z=1, a=8.3431(8) Å, b=9.2492(9) Å, c=8.3581(8) Å, α=84.72(1)°, β=89.68(1)°, γ =84.23(1)° (R1=0.041 (wR2=0.10) for 3291 reflections with Io>2σ(Io)) for Pr15B6C20, and a=8.284(1) Å, b=9.228(1) Å, c=8.309(1) Å, α=84.74(1)°, β=89.68(1)°, γ=84.17(2)° (R1=0.033 (wR2=0.049) for 2970 reflections with Io>2σ(Io)) for Nd15B6C20. Their structure consists of a three-dimensional framework of rare-earth metal atoms resulting from the stacking of slightly corrugated and distorted square nets, leading to cavities filled with unprecedented B2C4 finite chains, disordered C3 entities and isolated carbon atoms, respectively. Structural and theoretical analyses suggest the ionic formulation (RE3+)15([B2C4]6-)3([C3]4-)2(C4-)2·11ē. Accordingly, density functional theory calculations indicate that the compounds are metallic. Both structural arguments as well as energy calculations on different boron vs. carbon distributions in the B2C4 chains support the presence of a CBCCBC unit. Pr15B6C18 exhibits antiferromagnetic order at TN=7.9 K, followed by a meta-magnetic transition above a critical external field B>0.03 T. On the other hand, Nd15B6C18 is a ferromagnet below TC≈40 K.

High-Entropy Metal Diborides: A New Class of High-Entropy Materials and a New Type of Ultrahigh Temperature Ceramics

NASA Astrophysics Data System (ADS)

Gild, Joshua; Zhang, Yuanyao; Harrington, Tyler; Jiang, Sicong; Hu, Tao; Quinn, Matthew C.; Mellor, William M.; Zhou, Naixie; Vecchio, Kenneth; Luo, Jian

2016-11-01

Seven equimolar, five-component, metal diborides were fabricated via high-energy ball milling and spark plasma sintering. Six of them, including (Hf0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2, (Hf0.2Zr0.2Ta0.2Mo0.2Ti0.2)B2, (Hf0.2Zr0.2Mo0.2Nb0.2Ti0.2)B2, (Hf0.2Mo0.2Ta0.2Nb0.2Ti0.2)B2, (Mo0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2, and (Hf0.2Zr0.2Ta0.2Cr0.2Ti0.2)B2, possess virtually one solid-solution boride phase of the hexagonal AlB2 structure. Revised Hume-Rothery size-difference factors are used to rationalize the formation of high-entropy solid solutions in these metal diborides. Greater than 92% of the theoretical densities have been generally achieved with largely uniform compositions from nanoscale to microscale. Aberration-corrected scanning transmission electron microscopy (AC STEM), with high-angle annular dark-field and annular bright-field (HAADF and ABF) imaging and nanoscale compositional mapping, has been conducted to confirm the formation of 2-D high-entropy metal layers, separated by rigid 2-D boron nets, without any detectable layered segregation along the c-axis. These materials represent a new type of ultra-high temperature ceramics (UHTCs) as well as a new class of high-entropy materials, which not only exemplify the first high-entropy non-oxide ceramics (borides) fabricated but also possess a unique non-cubic (hexagonal) and layered (quasi-2D) high-entropy crystal structure that markedly differs from all those reported in prior studies. Initial property assessments show that both the hardness and the oxidation resistance of these high-entropy metal diborides are generally higher/better than the average performances of five individual metal diborides made by identical fabrication processing.

The use of moments of momentum to account for crystal habits

NASA Technical Reports Server (NTRS)

Barber, P. G.

1985-01-01

A three-step theory of crystal growth is proposed which involves first an association of molecules or ions in solution to form an impinging growth unit, then second the orientation of this unit prior to its impact on the surface of a crystal, and finally the attachment of this unit to the crystal face. From this theory the habit of a crystal is dependent upon the moments of momentum of the impinging growth unit. The results of sample calculations are presented or sodium chloride, succinic acid, sucrose, and chromium boride. The faces predicted by this proposed theory are compared with those predicted by other, energy-based calculations and with those experimentally observed. The proposed theory suggests alternative strategies for crystallization and habit modification which may be of technological importance. Listings of the two computer programs that were used are provided.

Superconductivity between standard types: Multiband versus single-band materials

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

Vagov, A.; Shanenko, A. A.; Milošević, M. V.

In the nearest vicinity of the critical temperature, types I and II of conventional single-band superconductors interchange at the Ginzburg-Landau parameter κ = 1/√2. At lower temperatures this point unfolds into a narrow but finite interval of κ’s, shaping an intertype (transitional) domain in the (κ,T ) plane. In the present work, based on the extended Ginzburg-Landau formalism, we show that the same picture of the two standard types with the transitional domain in between applies also to multiband superconductors. However, the intertype domain notably widens in the presence of multiple bands and can become extremely large when the systemmore » has a significant disparity between the band parameters. It is concluded that many multiband superconductors, such as recently discovered borides and iron-based materials, can belong to the intertype regime.« less

Liner for extrusion billet containers. Interim Technical Documentary Progress Report, February 1--April 30, 1963

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

Spachner, S. A.

1963-05-01

A shrink-fit assembly device for buildup of ceramiccoated liner and sleeve assemblies was tested and modified to develop desired temperatures and suitable heat distribution in sleeves, which were heated. Nine different compositions of fiber metal reinforced ceramic compacts were produced for 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. Dissassembly tooling for rapid separation of shrink-fitted sleeves from a worn liner was designed, fabricated, and tested. Preliminary extrusion testing of an alumina-coated liner was carried out,more » using SAE 4340 steel billets extruded to rod at 12 : 1 and 16 : 1 ratios. No coating wear was noted after extrusion of 3 billets. (auth)« less

Systematic investigation of structural, electronic, optical and thermal properties of ternary MoAlB; an ab initio approach

NASA Astrophysics Data System (ADS)

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

2018-02-01

Structural, electronic, optical and thermal properties of molybdenum aluminum boride (MoAlB) have been analyzed systematically using the full potential linearized augmented plane wave method based on density functional theory at ambient condition as well as high pressure and high temperature. Density of states and band structure calculation reflect the metallic character of MoAlB. In addition to this, the electron charge density calculation reveals the strong covalent bonding, in between ‘B’ atoms as well as ‘Mo’ and ‘B’ atoms. Optical parameters exhibit anisotropic nature and MoAlB become transparent in ultraviolet region for the radiation of energy above 25 eV. The thermal properties were investigated by using the quasi-harmonic Debye model at high temperature and high pressure.

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. Fundamental studies on the electronic and defect structures of the carbides indicate that there is promise for improving the strength and ductility of these materials. Studies of the zirconium-carbon-oxygen system show that zirconium oxycarbides of different compositions and lattice parameters can be formed between 1500 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.

Formation of Minor Phases in a Nickel-Based Disk Superalloy

NASA Technical Reports Server (NTRS)

Gabb, T. P.; Garg, A.; Miller, D. R.; Sudbrack, C. K.; Hull, D. R.; Johnson, D.; Rogers, R. B.; Gayda, J.; Semiatin, S. L.

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 approximate equilibrium. Additional heat treatments were also performed for shorter times, to then assess non-equilibrium conditions. Minor phases including MC carbides, M23C6 carbides, M3B2 borides, and sigma were identified. Their transformation temperatures, lattice parameters, compositions, average sizes and total area fractions were determined, and compared to estimates of an existing phase prediction software package. Parameters measured at equilibrium sometimes agreed reasonably well with software model estimates, with potential for further improvements. Results for shorter times representing non-equilibrium indicated significant potential for further extension of the software to such conditions, which are more commonly observed during heat treatments and service at high temperatures for disk applications.

Development and Characterization of Titanium Compound N anostructures

NASA Astrophysics Data System (ADS)

Zhou, Zhou

The development and characterization of titanium compound nanostructures have been achieved, for potential applications in energy industry. Oil and gas, one of the traditional industry fields, observes accumulating demands on active implementations of nanotechnology, for the numerous advantages that nanomaterials can introduce to both product performances and field operations. By using chemical vapor deposition and liquid exfoliation, various titanium compound nanostructures have been synthesized through this project. Attractively, these two material fabrication methods have been recognized to be industrial friendly in terms of cost efficiency and productivity. The development of nanostructures, aiming at oil and gas field applications, presents novel solutions for existing issues, such as low durability of drilling tools, high friction in mechanical operations and ineffective heat dissipation. Titanium compound nanostructures, including titanium borides, nitrides and sulfides are therefore investigated for such applications as protective coating, lubrication and thermal management.

Magnetic relaxation pathways in lanthanide single-molecule magnets.

PubMed

Blagg, Robin J; Ungur, Liviu; Tuna, Floriana; Speak, James; Comar, Priyanka; Collison, David; Wernsdorfer, Wolfgang; McInnes, Eric J L; Chibotaru, Liviu F; Winpenny, Richard E P

2013-08-01

Single-molecule magnets are compounds that exhibit magnetic bistability caused by an energy barrier for the reversal of magnetization (relaxation). Lanthanide compounds are proving promising as single-molecule magnets: recent studies show that terbium phthalocyanine complexes possess large energy barriers, and dysprosium and terbium complexes bridged by an N2(3-) radical ligand exhibit magnetic hysteresis up to 13 K. Magnetic relaxation is typically controlled by single-ion factors rather than magnetic exchange (whether one or more 4f ions are present) and proceeds through thermal relaxation of the lowest excited states. Here we report polylanthanide alkoxide cage complexes, and their doped diamagnetic yttrium analogues, in which competing relaxation pathways are observed and relaxation through the first excited state can be quenched. This leads to energy barriers for relaxation of magnetization that exceed 800 K. We investigated the factors at the lanthanide sites that govern this behaviour.

Controlling interactions between highly magnetic atoms with Feshbach resonances.

PubMed

Kotochigova, Svetlana

2014-09-01

This paper reviews current experimental and theoretical progress in the study of dipolar quantum gases of ground and meta-stable atoms with a large magnetic moment. We emphasize the anisotropic nature of Feshbach resonances due to coupling to fast-rotating resonant molecular states in ultracold s-wave collisions between magnetic atoms in external magnetic fields. The dramatic differences in the distribution of resonances of magnetic (7)S3 chromium and magnetic lanthanide atoms with a submerged 4f shell and non-zero electron angular momentum is analyzed. We focus on dysprosium and erbium as important experimental advances have been recently made to cool and create quantum-degenerate gases for these atoms. Finally, we describe progress in locating resonances in collisions of meta-stable magnetic atoms in electronic P-states with ground-state atoms, where an interplay between collisional anisotropies and spin-orbit coupling exists.

Proposal for the detection of magnetic monopoles in spin ice via nanoscale magnetometry

NASA Astrophysics Data System (ADS)

Kirschner, Franziska K. K.; Flicker, Felix; Yacoby, Amir; Yao, Norman Y.; Blundell, Stephen J.

2018-04-01

We present a proposal for applying nanoscale magnetometry to the search for magnetic monopoles in the spin ice materials holmium and dysprosium titanate. Employing Monte Carlo simulations of the dipolar spin ice model, we find that when cooled to below 1.5 K these materials exhibit a sufficiently low monopole density to enable the direct observation of magnetic fields from individual monopoles. At these temperatures we demonstrate that noise spectroscopy can capture the intrinsic fluctuations associated with monopole dynamics, allowing one to isolate the qualitative effects associated with both the Coulomb interaction between monopoles and the topological constraints implied by Dirac strings. We describe in detail three different nanoscale magnetometry platforms (muon spin rotation, nitrogen-vacancy defects, and nanoscale arrays of superconducting quantum interference devices) that can be used to detect monopoles in these experiments and analyze the advantages of each.

A physicochemical research of the Dy-Sn-O system

NASA Astrophysics Data System (ADS)

Malinovskaya, Tatyana; Lysak, Ilya; Zhek, Valentina; Kuznetsova, Svetlana

2017-11-01

A physicochemical research of the processes of phase composition formation in the materials of the Dy-Sn-O system was performed. Phase composition was taking place in the course of thermal treatment of dysprosium (III) and tin (IV) codeposition products. These were codeposited from nitrate solutions at pH 7, and 25% ammonia water was used as the precipitant. Using thermal and X-ray diffraction analysis, it was found that in the above system at 90 wt. % of Dy2O3 and 10 wt. % of SnO2, when the precursors were heated above 600°C there are no solid solutions. In the meanwhile, at temperatures below 1000°C there is only one phase, Dy2O3. At temperatures above 1000°C, the system becomes bi-phase and includes Dy2O3 and Dy2Sn2O7.

An Operationally Simple Method for Separating the Rare-Earth Elements Neodymium and Dysprosium.

PubMed

Bogart, Justin A; Lippincott, Connor A; Carroll, Patrick J; Schelter, Eric J

2015-07-06

Rare-earth metals are critical components of electronic materials and permanent magnets. Recycling of consumer materials is a promising new source of rare earths. To incentivize recycling there is a clear need for simple methods for targeted separations of mixtures of rare-earth metal salts. Metal complexes of a tripodal nitroxide ligand [{(2-(t) BuNO)C6 H4 CH2 }3 N](3-) (TriNOx(3-) ), feature a size-sensitive aperture formed of its three η(2) -(N,O) ligand arms. Exposure of metal cations in the aperture induces a self-associative equilibrium comprising [M(TriNOx)thf]/ [M(TriNOx)]2 (M=rare-earth metal). Differences in the equilibrium constants (Keq ) for early and late metals enables simple Nd/Dy separations through leaching with a separation ratio SNd/Dy =359. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Persistent Luminescence in Non-Eu2+-Doped Compounds: A Review

PubMed Central

Van den Eeckhout, Koen; Poelman, Dirk; Smet, Philippe F.

2013-01-01

During the past few decades, the research on persistent luminescent materials has focused mainly on Eu2+-doped compounds. However, the yearly number of publications on non-Eu2+-based materials has also increased steadily. By now, the number of known persistent phosphors has increased to over 200, of which over 80% are not based on Eu2+, but rather, on intrinsic host defects, transition metals (manganese, chromium, copper, etc.) or trivalent rare earths (cerium, terbium, dysprosium, etc.). In this review, we present an overview of these non-Eu2+-based persistent luminescent materials and their afterglow properties. We also take a closer look at some remaining challenges, such as the excitability with visible light and the possibility of energy transfer between multiple luminescent centers. Finally, we summarize the necessary elements for a complete description of a persistent luminescent material, in order to allow a more objective comparison of these phosphors. PMID:28811409

Modulating the single-molecule magnet behaviour in phenoxo-O bridged Dy2 systems via subtle structural variations

NASA Astrophysics Data System (ADS)

Wang, Wen-Min; Zhao, Xiao-Yu; Qiao, Hui; Bai, Li; Han, Hong-Fei; Fang, Ming; Wu, Zhi-Lei; Zou, Ji-Yong

2017-09-01

In search of simple approaches to rationally modulate the single-molecule magnet behaviour in polynuclear lanthanide compound, a new system containing two structurally closely related dinuclear dysprosium complexes, namely [Dy2(hfac)4L2] (1) and [Dy2(hfac)4L‧2] (2) (hfac = hexafluoroacetylacetonate, HL = 2-[4-methylaniline-imino]methyl]-8-hydroxyquinoline and HL' = 2-[(3,4-dimethylaniline)-imino]methyl]-8-hydroxyquinoline), are successfully synthesized and the structure-dependent magnetic properties are investigated. The two Dy2 compounds display only slight variations in the coordination geometries of the center Dy(III) ion but display remarkably different single-molecule magnet behaviors with the anisotropic barriers (ΔE/kB) of 9.91 K for 1 and 20.57 K for 2. The different magnetic relaxation behaviors of the two Dy2 complexes mainly originate from the different chemical environments of the central DyIII ions.

Dysprosium-159 for transmission imaging and bone mineral analysis.

PubMed

Rao, D V; Govelitz, G F; Sastry, K S

1977-01-01

The suitability of the intense Kalpha x rays of terbium emitted in the electron-capture decay of 159Dy for use in transmission imaging and bone mineral analysis is investigated. It is found that this radionuclide offers all the advantages of radiations from 210 Pb and none of the disadvantages inherent in the use of the latter. Yields of the Kalpha and Kbeta x rays of terbium and the 58-keV gamma rays emitted in 159 Dy decay are determined using a high-resolution Si(Li) photon spectrometer. Attenuation coefficients for these photons in gadolinium (critical) absorber are measured in a narrow-beam geometry. For Tb Kbeta x rays, whose average energy is only about 0.4 keV above the K edge or Gd, our experimental attenuation coefficient is about 10% less than the theoretical value given by Storm and Israel. Transmission images of regular and irregular bones obtained using 159Dy are presented.

Dirac strings and magnetic monopoles in the spin ice Dy2Ti2O7.

PubMed

Morris, D J P; Tennant, D A; Grigera, S A; Klemke, B; Castelnovo, C; Moessner, R; Czternasty, C; Meissner, M; Rule, K C; Hoffmann, J-U; Kiefer, K; Gerischer, S; Slobinsky, D; Perry, R S

2009-10-16

Sources of magnetic fields-magnetic monopoles-have so far proven elusive as elementary particles. Condensed-matter physicists have recently proposed several scenarios of emergent quasiparticles resembling monopoles. A particularly simple proposition pertains to spin ice on the highly frustrated pyrochlore lattice. The spin-ice state is argued to be well described by networks of aligned dipoles resembling solenoidal tubes-classical, and observable, versions of a Dirac string. Where these tubes end, the resulting defects look like magnetic monopoles. We demonstrated, by diffuse neutron scattering, the presence of such strings in the spin ice dysprosium titanate (Dy2Ti2O7). This is achieved by applying a symmetry-breaking magnetic field with which we can manipulate the density and orientation of the strings. In turn, heat capacity is described by a gas of magnetic monopoles interacting via a magnetic Coulomb interaction.

Superconducting composite with multilayer patterns and multiple buffer layers

DOEpatents

Wu, X.D.; Muenchausen, R.E.

1993-10-12

An article of manufacture is described including a substrate, a patterned interlayer of a material selected from the group consisting of magnesium oxide, barium-titanium oxide or barium-zirconium oxide, the patterned interlayer material overcoated with a secondary interlayer material of yttria-stabilized zirconia or magnesium-aluminum oxide, upon the surface of the substrate whereby an intermediate article with an exposed surface of both the overcoated patterned interlayer and the substrate is formed, a coating of a buffer layer selected from the group consisting of cerium oxide, yttrium oxide, curium oxide, dysprosium oxide, erbium oxide, europium oxide, iron oxide, gadolinium oxide, holmium oxide, indium oxide, lanthanum oxide, manganese oxide, lutetium oxide, neodymium oxide, praseodymium oxide, plutonium oxide, samarium oxide, terbium oxide, thallium oxide, thulium oxide, yttrium oxide and ytterbium oxide over the entire exposed surface of the intermediate article, and, a ceramic superconductor. 5 figures.

Bridgman growth and luminescence properties of dysprosium doped lead potassium niobate crystal

NASA Astrophysics Data System (ADS)

Liu, Wenbin; Tian, Tian; Yang, Bobo; Xu, Jiayue; Liu, Hongde

2017-06-01

Dy-doped lead potassium niobate (Pb2KNb5O15, PKN) single crystal was grown by the modified vertical Bridgman method through spontaneous nucleation. The crystal was brownish, transparent and inclusion free. Five excitation peaks of Dy3+ ions were clearly seen from near ultraviolet region to blue range. It was unique that the excitation peaks in blue range were more intense, especially the one centered at 455 nm. The emission bands consisted of blue, yellow and red emissions, which were at about 487 nm, 573 nm and 662 nm respectively. The CIE chromaticity diagram of PKN:Dy indicated that white light and yellow light could be emitted when the crystal was excited under near ultraviolet light and blue light, respectively. Thus PKN:Dy crystal is a candidate material whose emitting light could be tunable through changing the excited light wavelength.

Metallic rare-earth silicide nanowires on silicon surfaces.

PubMed

Dähne, Mario; Wanke, Martina

2013-01-09

The formation, atomic structure, and electronic properties of self-assembled rare-earth silicide nanowires on silicon surfaces were studied by scanning tunneling microscopy and angle-resolved photoelectron spectroscopy. Metallic dysprosium and erbium silicide nanowires were observed on both the Si(001) and Si(557) surfaces. It was found that they consist of hexagonal rare-earth disilicides for both surface orientations. On Si(001), the nanowires are characterized by a one-dimensional band structure, while the electronic dispersion is two-dimensional for the nanowires formed on Si(557). This behavior is explained by the different orientations of the hexagonal c axis of the silicide leading to different conditions for the carrier confinement. By considering this carrier confinement it is demonstrated how the one-dimensional band structure of the nanowires on Si(001) can be derived from the two-dimensional one of the silicide monolayer on Si(111).

Biological fabrication of cellulose fibers with tailored properties.

PubMed

Natalio, Filipe; Fuchs, Regina; Cohen, Sidney R; Leitus, Gregory; Fritz-Popovski, Gerhard; Paris, Oskar; Kappl, Michael; Butt, Hans-Jürgen

2017-09-15

Cotton is a promising basis for wearable smart textiles. Current approaches that rely on fiber coatings suffer from function loss during wear. We present an approach that allows biological incorporation of exogenous molecules into cotton fibers to tailor the material's functionality. In vitro model cultures of upland cotton ( Gossypium hirsutum ) are incubated with 6-carboxyfluorescein-glucose and dysprosium-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid-glucose, where the glucose moiety acts as a carrier capable of traveling from the vascular connection to the outermost cell layer of the ovule epidermis, becoming incorporated into the cellulose fibers. This yields fibers with unnatural properties such as fluorescence or magnetism. Combining biological systems with the appropriate molecular design offers numerous possibilities to grow functional composite materials and implements a material-farming concept. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Dysprosium-free melt-spun permanent magnets.

PubMed

Brown, D N; Wu, Z; He, F; Miller, D J; Herchenroeder, J W

2014-02-12

Melt-spun NdFeB powders can be formed into a number of different types of permanent magnet for a variety of applications in electronics, automotive and clean technology industries. The melt-spinning process produces flake powder with a fine uniform array of nanoscale Nd2Fe14B grains. These powders can be net-shape formed into isotropic polymer-bonded magnets or hot formed into fully dense magnets. This paper discusses the influence of heavy rare earth elements and microstructure on the magnetic performance, thermal stability and material cost of NdFeB magnets. Evidence indicates that melt-spun nanocrystalline NdFeB magnets are less dependent on heavy rare earth elements for high-temperature performance than the alternative coarser-grained sintered NdFeB magnets. In particular, hot-pressed melt-spun magnets are an attractive low-cost solution for applications that require thermal stability up to 175-200 °C.

Synthesis and characterization of a family of structurally characterized dysprosium alkoxides for improved fatigue-resistance characteristics of PDyZT thin films.

PubMed

Boyle, Timothy J; Bunge, Scott D; Clem, Paul G; Richardson, Jacob; Dawley, Jeffrey T; Ottley, Leigh Anna M; Rodriguez, Mark A; Tuttle, Bruce A; Avilucea, Gabriel R; Tissot, Ralph G

2005-03-07

Using either an ammoniacal route, the reaction between DyCl3, Na0, and HOR in liquid ammonia, or preferentially reacting Dy(N(SiMe3)2)3 with HOR in a solvent, we isolated a family of dysprosium alkoxides as [Dy(mu-ONep)2(ONep)]4 (1), (ONep)2Dy[(mu3-ONep)(mu-ONep)Dy(ONep)(THF)]2(mu-ONep) (2), (ONep)2Dy[(mu3-ONep)(mu-ONep)Dy(ONep)(py)]2(mu-ONep) (3), [Dy3(mu3-OBut)2(mu-OBut3(OBut)4(HOBut)2] (4), [Dy3(mu3-OBut)2(mu-OBut)3(OBut)4(THF)2] (5), [Dy3(mu3-OBut)2(mu-OBut)3(OBut)4(py)2] (6), (DMP)Dy(mu-DMP)4[Dy(DMP)2(NH3)]2 (7), [Dy(eta6-DMP)(DMP)2]2 (8), Dy(DMP)3(THF)3 (9), Dy(DMP)3(py)3 (10), Dy(DIP)3(NH3)2 (11), [Dy(eta6-DIP)(DIP)2]2 (12), Dy(DIP)3(THF)2 (13), Dy(DIP)3(py)3 (14), Dy(DBP)3(NH3) (15), Dy(DBP)3 (16), Dy(DBP)3(THF) (17), Dy(DBP)3(py)2 (18), [Dy(mu-TPS)(TPS2]2 (19), Dy(TPS)3(THF)3 (20), and Dy(TPS)3(py)3 (21), where ONep = OCH2CMe3, OBut) = OCMe3, DMP = OC6H3(Me)(2)-2,6, DIP = OC6H3(CHMe2)(2)-2,6, DBP = OC6H3(CMe3)(2)-2,6, TPS = OSi(C6H5)3, tol = toluene, THF = tetrahydrofuran, and py = pyridine. We were not able to obtain X-ray quality crystals of compounds 2, 8, and 9. The structures observed and data collected for the Dy compounds are consistent with those reported for its other congeners. A number of these precursors were used as Dy dopants in Pb(Zr0.3Ti0.7)O3 (PZT 30/70) thin films, with compound 12 yielding the highest-quality films. The resulting Pb0.94Dy0.04(Zr0.3Ti0.7)O3 [PDyZT (4/30/70)] had similar properties to PZT (30/70), but showed substantial resistance to polarization reversal fatigue.

Mixed-metal effects on ultra-incompressible metal diborides: Density functional computations

NASA Astrophysics Data System (ADS)

Lin, Fei; Wu, Kechen; He, Jiangang; Sa, Rongjian; Li, Qiaohong; Wei, Yongqin

2010-07-01

Mixed-metal borides are promising superhard materials (Kaner et al. (2005) [1]). In this Letter, density functional computations have been applied to the structural, electronic and elastic properties of mixed-metal diborides Re 0.5Ir 0.5B 2, Re 0.5Tc 0.5B 2, Os 0.5W 0.5B 2 and Os 0.5Ru 0.5B 2. The elastic moduli decrease from pure metal diboride ReB 2 to Re 0.5Ir 0.5B 2 and on the contrary increase from OsB 2 to Os 0.5W 0.5B 2 because boron-metal interactions are contaminated by the occupied anti-bonding orbitals. Alloying ReB 2 (OsB 2) with Tc (Ru) decreases the elastic moduli owing to the relativistic effects. Mixed-metal effects on elastic deformations focus on bonding strengths, which effectively tune the elastic properties of metal diborides.

Mechanical characteristics of heterogeneous structures obtained by high-temperature brazing of corrosion-resistant steels with rapidly quenched non-boron nickel-based alloys

NASA Astrophysics Data System (ADS)

Kalin, B.; Penyaz, M.; Ivannikov, A.; Sevryukov, O.; Bachurina, D.; Fedotov, I.; Voennov, A.; Abramov, E.

2018-01-01

Recently, the use rapidly quenched boron-containing nickel filler metals for high temperature brazing corrosion resistance steels different classes is perspective. The use of these alloys leads to the formation of a complex heterogeneous structure in the diffusion zone that contains separations of intermediate phases such as silicides and borides. This structure negatively affects the strength characteristics of the joint, especially under dynamic loads and in corrosive environment. The use of non-boron filler metals based on the Ni-Si-Be system is proposed to eliminate this structure in the brazed seam. Widely used austenitic 12Cr18Ni10Ti and ferrite-martensitic 16Cr12MoSiWNiVNb reactor steels were selected for research and brazing was carried out. The mechanical characteristics of brazed joints were determined using uniaxial tensile and impact toughness tests, and fractography was investigated by electron microscopy.

Structure and properties of Hardox 450 steel with arc welded coatings

NASA Astrophysics Data System (ADS)

Ivanov, Yu. F.; Konovalov, S. V.; Kormyshev, V. E.; Gromov, V. E.; Teresov, A. D.; Semina, O. A.

2017-12-01

The paper reports on a study of the surface structure, phase composition, and microhardness of Hardox 450 steel with coatings deposited by arc welding of powder wires differing in chemical composition. The study shows that to a depth of 6-8 mm, the microhardness of the thus formed coatings is more than two times the microhardness of the base metal and that their higher mechanical properties are provided by martensite structure containing Nb2C and NbC carbides and Fe2B borides as eutectic lamellae with a transverse size of 30-70 nm; their volume reveals a net-like dislocation substructure with a scalar dislocation density of 1011 cm-2. The highest surface hardness is found for the steel coated with boron-containing wire material. Some ideas are suggested on possible mechanisms and temperature for the formation of Nb and B carbides during the process.

Impact of B 4C co-sputtering on structure and optical performance of Cr/Sc multilayer X-ray mirrors

DOE PAGES

Ghafoor, Naureen; Eriksson, Fredrik; Aquila, Andrew; ...

2017-01-01

We investigate the influence of B 4C incorporation during magnetron sputter deposition of Cr/Sc multilayers intended for soft X-ray reflective optics. Chemical analysis suggests formation of metal: boride and carbide bonds which stabilize an amorphous layer structure, resulting in smoother interfaces and an increased reflectivity. A near-normal incidence reflectivity of 11.7%, corresponding to a 67% increase, is achieved at λ = 3.11 nm upon adding 23 at.% (B + C). The advantage is significant for the multilayer periods larger than 1.8 nm, where amorphization results in smaller interface widths, for example, giving 36% reflectance and 99.89% degree of polarization nearmore » Brewster angle for a multilayer polarizer. The modulated ion-energy-assistance during the growth is considered vital to avoid intermixing during the interface formation even when B + C are added.« less

Review of Thermal Spray Coating Applications in the Steel Industry: Part 2—Zinc Pot Hardware in the Continuous Galvanizing Line

NASA Astrophysics Data System (ADS)

Matthews, S.; James, B.

2010-12-01

This two-part article series reviews the application of thermal spray coating technology in the production of steel and steel sheet products. Part 2 of this article series is dedicated to coating solutions in the continuous galvanizing line. The corrosion mechanisms of Fe- and Co-based bulk materials are briefly reviewed as a basis for the development of thermal spray coating solutions. WC-Co thermal spray coatings are commonly applied to low Al-content galvanizing hardware due to their superior corrosion resistance compared to Fe and Co alloys. The effect of phase degradation, carbon content, and WC grain size are discussed. At high Al concentrations, the properties of WC-Co coatings degrade significantly, leading to the application of oxide-based coatings and corrosion-resistant boride containing coatings. The latest results of testing are summarized, highlighting the critical coating parameters.

Microstructural observations in rapidly-solidified and heat-treated Ni3Al-Cr alloys

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

Carro, G.; Flanagan, W.F.

1992-08-01

The microstructural development following heat treatments of several rapidly-solidified Ni3Al-Cr and Ni3Al-Cr-B alloys is presented. Depending on composition, the as-solidified samples were either 100 percent gamma-prime phase - in the form of fine antiphase domains (APD) - or a mixture of gamma-prime (APDs) and beta phases. Upon annealing, the as-solidified microstructures transform to either APD-free gamma-prime or mixtures of gamma and gamma-prime phases. For those compositions where the quenched microstructures were 100 percent gamma-prime it was observed that APD coarsening followed conventional grain-growth kinetics, but when gamma phase precipitated on the APD boundaries the rate constant changed abruptly while themore » time exponent remained unaffected. It was also found that alloys containing critical amounts of chromium and boron are susceptible to precipitation of the boride Cr5B3. 14 refs.« less

Microstructural observations in rapidly-solidified and heat-treated Ni sub 3 Al-Cr alloys

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

Carro, G.; Flanagan, W.F.

1992-01-01

In this paper , the microstructural development following heat treatments of several rapidly-solidified Ni{sub 3}Al-Cr and Ni{sub 3}Al-Cr-B alloys is presented. Depending on composition, the as-solidified samples were either 100% {gamma} phase-in the form of fine anti-phase domains (APD)-or a mixture of {gamma} (APDs) and {beta} phases. Upon annealing, the as-solidified microstructures transform to either APD-free {gamma}or mixtures of {gamma}and {gamma}{prime} phases. For those compositions where the quenched microstructures were 100{gamma}{prime} it was observed that APD coarsening followed conventional grain-growth kinetics, but when {gamma} phase precipitated on the APD boundaries the rate constant changed abruptly while the time exponent remainedmore » unaffected. It was also found that alloys containing critical amounts of chromium and boron are susceptible to precipitation of the boride Cr{sub 5}B{sub 3}.« less

Microstructural observations in rapidly-solidified and heat-treated Ni3Al-Cr alloys

NASA Technical Reports Server (NTRS)

Carro, G.; Flanagan, W. F.

1992-01-01

The microstructural development following heat treatments of several rapidly-solidified Ni3Al-Cr and Ni3Al-Cr-B alloys is presented. Depending on composition, the as-solidified samples were either 100 percent gamma-prime phase - in the form of fine antiphase domains (APD) - or a mixture of gamma-prime (APDs) and beta phases. Upon annealing, the as-solidified microstructures transform to either APD-free gamma-prime or mixtures of gamma and gamma-prime phases. For those compositions where the quenched microstructures were 100 percent gamma-prime it was observed that APD coarsening followed conventional grain-growth kinetics, but when gamma phase precipitated on the APD boundaries the rate constant changed abruptly while the time exponent remained unaffected. It was also found that alloys containing critical amounts of chromium and boron are susceptible to precipitation of the boride Cr5B3.

Effects of cobalt on the microstructure of Udimet 700. M.S. Thesis Final Report

NASA Technical Reports Server (NTRS)

Engel, M. A.

1982-01-01

Cobalt, a critical and "strategic" alloying element in many superalloys, was systematically substituted by nickel in experimental alloys Udimet 700 containing 0.1, 4.3, 8.6, 12.8 and the standard 17.0 wt.% cobalt. Electrolytic and chemical extraction techniques, X-ray diffraction, scanning electron and optical microscopy were used for the microstructural studies. The total weight fraction of gamma' was not significantly affected by the cobalt content, although a difference in the size and quantities of the primary and secondary gamma' phases was apparent. The lattice parameters of the gamma' were found to increase with increasing cobalt content while the lattice mismatch between the gamma matrix and gamma' phases decreased. Other significant effects of cobalt on the weight fraction, distribution and formation of the carbide and boride phases as well as the relative stability of the experimental alloys during long-time aging are also discussed.

Impact of B 4C co-sputtering on structure and optical performance of Cr/Sc multilayer X-ray mirrors

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

Ghafoor, Naureen; Eriksson, Fredrik; Aquila, Andrew

We investigate the influence of B 4C incorporation during magnetron sputter deposition of Cr/Sc multilayers intended for soft X-ray reflective optics. Chemical analysis suggests formation of metal: boride and carbide bonds which stabilize an amorphous layer structure, resulting in smoother interfaces and an increased reflectivity. A near-normal incidence reflectivity of 11.7%, corresponding to a 67% increase, is achieved at λ = 3.11 nm upon adding 23 at.% (B + C). The advantage is significant for the multilayer periods larger than 1.8 nm, where amorphization results in smaller interface widths, for example, giving 36% reflectance and 99.89% degree of polarization nearmore » Brewster angle for a multilayer polarizer. The modulated ion-energy-assistance during the growth is considered vital to avoid intermixing during the interface formation even when B + C are added.« less

Energy conversion device and method of reducing friction therein

DOEpatents

Solovyeva, Lyudmila Mikhaylovna; Jansson, Kyle S; Elmoursi, Alaa AbdelAzim; Zhu, Dong; Milner, Robert; Daughterty, Early Eugene; Higdon, Clifton Baxter; Elagamy, Kamel Abdel-Khalik; Hicks, Aaron Michael

2013-10-08

A device configured for converting energy includes a first surface, a second surface configured for moving with respect to the first surface during operation of the device, and a coating disposed on at least one of the first surface and the second surface. The coating includes a first layer of a ceramic alloy represented by the general formula AlMgB.sub.14--X, wherein X is present in an amount of from 0 to 70 parts by weight based on 100 parts by weight of the ceramic alloy and is a doping agent selected from the group of Group IV elements and borides and nitrides thereof, and a second layer disposed on the first layer and including carbon in a gradient concentration. The coating has a hardness of from 10 to 20 GPa and a coefficient of friction of less than or equal to 0.12.

Wet-chemical synthesis of nanoscale iron boride, XAFS analysis and crystallisation to α-FeB.

PubMed

Rades, Steffi; Kornowski, Andreas; Weller, Horst; Albert, Barbara

2011-06-20

The reaction of lithium tetrahydridoborate and iron bromide in high boiling ether as reaction medium produces an ultrafine, pyrophoric and magnetic precipitate. X-ray and electron diffraction proved the product to be amorphous. According to X-ray absorption fine structure spectroscopy (XAFS) the precipitate has FeB structure up to nearly two coordination spheres around an iron absorber atom. Transmission electron microscopy (TEM) confirms the ultrafine powder to be nanoscale. Subsequent annealing at 450 °C causes the atoms to arrange in a more distinct FeB structure, and further thermal treatment to 1050 °C extends the local structure to the α-modification of FeB. Between 1050 °C and 1500 °C α-FeB is transformed into β-FeB. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of Laser Power on Metallurgical, Mechanical and Tribological Characteristics of Hardfaced Surfaces of Nickel-Based Alloy

NASA Astrophysics Data System (ADS)

Gnanasekaran, S.; Padmanaban, G.; Balasubramanian, V.

2017-12-01

In this present work, nickel based alloy was deposited on 316 LN austenitic stainless steel (ASS) by a laser hardfacing technique to investigate the influence of laser power on macrostructure, microstructure, microhardness, dilution and wear characteristics. The laser power varied from 1.1 to 1.9 kW. The phase constitution, microstructure and microhardness were examined by optical microscope, scanning electron microscopy, energy dispersion spectroscopy and Vickers microhardness tester. The wear characteristics of the hardfaced surfaces and substrate were evaluated at room temperature (RT) under dry sliding wear condition (pin-on-disc). The outcome demonstrates that as the laser power increases, dilution increases and hardness of the deposit decreases. This is because excess heat melts more volume of substrate material and increases the dilution; subsequently it decreases the hardness of the deposit. The microstructure of the deposit is characterized by Ni-rich carbide, boride and silicide.

Techniques for increasing boron fiber fracture strain

NASA Technical Reports Server (NTRS)

Dicarlo, J. A.

1977-01-01

Improvement in the strain-to-failure of CVD boron fibers is shown possible by contracting the tungsten boride core region and its inherent flaws. The results of three methods are presented in which etching and thermal processing techniques were employed to achieve core flaw contraction by internal stresses available in the boron sheath. After commercially and treatment induced surface flaws were removed from 203 micrometers (8 mil) fibers, the core flaw was observed to be essentially the only source of fiber fracture. Thus, fiber strain-to-failure was found to improve by an amount equal to the treatment induced contraction on the core flaw. Commercial feasibility considerations suggest as the most cost effective technique that method in which as-produced fibers are given a rapid heat treatment above 700 C. Preliminary results concerning the contraction kinetics and fracture behavior observed are presented and discussed both for high vacuum and argon gas heat treatment environments.

Refractory materials for high-temperature thermoelectric energy conversion

NASA Technical Reports Server (NTRS)

Wood, C.; Emin, D.

1983-01-01

Theoretical work of two decades ago adequately explained the transport behavior and effectively guided the development of thermoelectric materials of high conversion efficiencies of conventional semiconductors (e.g., SiGe alloys). The more significant contributions involved the estimation of optimum doping concentrations, the reduction of thermal conductivity by solid solution doping and the development of a variety of materials with ZT approx. 1 in the temperature range 300 K to 1200 K. ZT approx. 1 is not a theoretical limitation although, experimentally, values in excess of one were not achieved. Work has continued with emphasis on higher temperature energy conversion. A number of promising materials have been discovered in which it appears that ZT 1 is realizable. These materials are divided into two classes: (1) the rare-earth chalcogenides which behave as itinerant highly-degenerate n-type semiconductors at room-temperature, and (2) the boron-rich borides, which exhibit p-type small-polaronic hopping conductivity.

The microstructure and properties of rapidly solidified, dispersion-strengthened NiAl

NASA Technical Reports Server (NTRS)

Jha, S. C.; Ray, R.

1990-01-01

An advanced rapid solidification technology for processing reactive and refractory alloys, utilized to produce large quantities of melt-spun filaments of NiAl, is presented. The melt-spun filaments are pulverized to fine particle sizes, and subsequently consolidated by hot extrusion or hot isostatic pressing. Rapid solidification process gives rise to very fine-grained microstructures. However, exposure to elevated temperature during hot consolidation leads to grain growth. Alloying agents such as borides, carbides, and tungsten can pin the grain boundaries and retard the grain growth. Various alloy compositions are investigated. The eventual goal is to utilize the hot-extruded and forged stock to grow single-crystal NiAl blades for advanced gas-turbine engine applications. Single-crystal NiAl, containing a uniform dispersion of carbide strengthening precipitates, is expected to lead to highly creep-resistant turbine blades, and is of considerable interest to the aerospace propulsion industry.

Fracture Strength of AlLiB14

NASA Astrophysics Data System (ADS)

Wan, L. F.; Beckman, S. P.

2012-10-01

The orthorhombic boride crystal family XYB14, where X and Y are metal atoms, plays a critical role in a unique class of superhard compounds, yet there have been no studies aimed at understanding the origin of the mechanical strength of this compound. We present here the results from a comprehensive investigation into the fracture strength of the archetypal AlLiB14 crystal. First principles, ab initio, methods are used to determine the ideal brittle cleavage strength for several high-symmetry orientations. The elastic tensor and the orientation-dependent Young’s modulus are calculated. From these results the lower bound fracture strength of AlLiB14 is predicted to be between 29 and 31 GPa, which is near the measured hardness reported in the literature. These results indicate that the intrinsic strength of AlLiB14 is limited by the interatomic B-B bonds that span between the B layers.

(Pt1-xCux)3Cu2B and Pt9Cu3B5, the first examples of copper platinum borides. Observation of superconductivity in a novel boron filled β-Mn-type compound

NASA Astrophysics Data System (ADS)

Salamakha, Leonid P.; Sologub, Oksana; Stöger, Berthold; Michor, Herwig; Bauer, Ernst; Rogl, Peter F.

2015-09-01

New ternary copper platinum borides have been synthesized by arc melting of pure elements followed by annealing at 600 °C. The structures have been studied by X-ray single crystal and powder diffraction. (Pt1-xCux)3Cu2B (x=0.33) forms a B-filled β-Mn-type structure (space group P4132; a=0.6671(1) nm). Cu atoms are distributed preferentially on the 8c atom sites, whereas the 12d site is randomly occupied by Pt and Cu atoms (0.670(4) Pt±0.330(4) Cu). Boron is located in octahedral voids of the parent β-Mn-type structure. Pt9Cu3B5 (space group P-62m; a=0.9048(3) nm, c=0.2908(1) nm) adopts the Pt9Zn3B5-δ-type structure. It has a columnar architecture along the short translation vector exhibiting three kinds of [Pt6] trigonal prism columns (boron filled, boron semi-filled and empty) and Pt channels with a pentagonal cross section filled with Cu atoms. The striking structural feature is a [Pt6] cluster in form of an empty trigonal prism at the origin of the unit cell, which is surrounded by coupled [BPt6] and [Pt6] trigonal prisms, rotated perpendicularly to the central one. There is no B-B contact as well as Cu-B contact in the structure. The relationships of Pt9Cu3B5 structure with the structure of Ti1+xOs2-xRuB2 as well as with the structure families of metal sulfides and aluminides have been elucidated. (Pt1-xCux)3Cu2B (x=0.3) (B-filled β-Mn-type structure) is a bulk superconductor with a transition temperature of about 2.06 K and an upper critical field μ0HC2(0)WHH of 1.2 T, whereas no superconducting transition has been observed up to 0.3 K in Pt9Cu3B5 (Pt9Zn3B5-δ-type structure) from electrical resistivity measurements.

Synthesis and characterization of CaF2:Dy nanophosphor for dosimetric application

NASA Astrophysics Data System (ADS)

Bhadane, Mahesh S.; Patil, B. J.; Dahiwale, S. S.; Kulkarni, M. S.; Bhatt, B. C.; Bhoraskar, V. N.; Dhole, S. D.

2015-06-01

In this work, nanoparticles (NPs) of dysprosium doped calcium fluoride (CaF2:Dy) 1 mol % has been prepared using simple chemical co-precipitation method and its thermoluminescence (TL) dosimetric properties were studied. The synthesized nanoparticle sample was characterized by X-ray diffraction (XRD) and the particle size of face centered cubic phase NPs was found around 30 nm. The shape, morphology and size were also observed by scanning electron microscopy (SEM). From gamma irradiated CaF2:Dy TL curves, it was observed that the total areas of all the glow peak intensities are dramatically changed with increase in annealing temperature. Further, TL glow curve of the CaF2:Dy at 183 °C annealed at 400 °C, showed very sharp linear response in the dose range from 1 Gy to 750 Gy. This linear response of CaF2:Dy nanophosphor as a function of gamma dose is very useful from radiation dosimetric point of view.

A primary exploration to quasi-two-dimensional rare-earth ferromagnetic particles: holmium-doped MoS2 sheet as room-temperature magnetic semiconductor

NASA Astrophysics Data System (ADS)

Chen, Xi; Lin, Zheng-Zhe

2018-05-01

Recently, two-dimensional materials and nanoparticles with robust ferromagnetism are even of great interest to explore basic physics in nanoscale spintronics. More importantly, room-temperature magnetic semiconducting materials with high Curie temperature is essential for developing next-generation spintronic and quantum computing devices. Here, we develop a theoretical model on the basis of density functional theory calculations and the Ruderman-Kittel-Kasuya-Yoshida theory to predict the thermal stability of two-dimensional magnetic materials. Compared with other rare-earth (dysprosium (Dy) and erbium (Er)) and 3 d (copper (Cu)) impurities, holmium-doped (Ho-doped) single-layer 1H-MoS2 is proposed as promising semiconductor with robust magnetism. The calculations at the level of hybrid HSE06 functional predict a Curie temperature much higher than room temperature. Ho-doped MoS2 sheet possesses fully spin-polarized valence and conduction bands, which is a prerequisite for flexible spintronic applications.

Sub-molecular modulation of a 4f driven Kondo resonance by surface-induced asymmetry

NASA Astrophysics Data System (ADS)

Warner, Ben; El Hallak, Fadi; Atodiresei, Nicolae; Seibt, Philipp; Prüser, Henning; Caciuc, Vasile; Waters, Michael; Fisher, Andrew J.; Blügel, Stefan; van Slageren, Joris; Hirjibehedin, Cyrus F.

2016-09-01

Coupling between a magnetic impurity and an external bath can give rise to many-body quantum phenomena, including Kondo and Hund's impurity states in metals, and Yu-Shiba-Rusinov states in superconductors. While advances have been made in probing the magnetic properties of d-shell impurities on surfaces, the confinement of f orbitals makes them difficult to access directly. Here we show that a 4f driven Kondo resonance can be modulated spatially by asymmetric coupling between a metallic surface and a molecule containing a 4f-like moment. Strong hybridization of dysprosium double-decker phthalocyanine with Cu(001) induces Kondo screening of the central magnetic moment. Misalignment between the symmetry axes of the molecule and the surface induces asymmetry in the molecule's electronic structure, spatially mediating electronic access to the magnetic moment through the Kondo resonance. This work demonstrates the important role that molecular ligands have in mediating electronic and magnetic coupling and in accessing many-body quantum states.

The influence of post-deposition annealing on the structure, morphology and luminescence properties of pulsed laser deposited La0.5Gd1.5SiO5 doped Dy3+ thin films

NASA Astrophysics Data System (ADS)

Ogugua, Simon N.; Swart, Hendrik C.; Ntwaeaborwa, Odireleng M.

2018-04-01

The influence of post-deposition annealing on the structure, particle morphology and photoluminescence properties of dysprosium (Dy3+) doped La0.5Gd1.5SiO5 thin films grown on Si(111) substrates at different substrate temperatures using pulsed laser deposition (PLD) technique were studied. The X-ray diffractometer results showed an improved crystallinity after post-annealing. The topography and morphology of the post-annealed films were studied using atomic force microscopy and field emission scanning electron microscopy respectively. The elemental composition in the surface region of the films were analyzed using energy dispersive X-ray spectroscopy. The photoluminescence studies showed an improved luminescent after post-annealing. The cathodoluminescence properties of the films are also reported. The CIE colour coordinates calculated from the photoluminescence and cathodoluminescence data suggest that the films can have potential application in white light emitting diode (LED) and field emission display (FED) applications.

Cryogenic Field Measurement of Pr2Fe14B Undulator and Performance Enhancement Options at the NSLS-II

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

Tanabe, T.; Chubar, O.; Harder, David A.

2009-09-27

Short period (14.5mm) hybrid undulator arrays composed of Praseodymium Iron Boron (Pr{sub 2}Fe{sub 14}B) magnets (CR53, NEOMAX, Inc.) and vanadium permendur poles have been fabricated at Brookhaven National Laboratory. Unlike Neodymium Iron Boron (Nd{sub 2}Fe{sub 14}B) magnets which exhibit spin reorientation at temperatures below 150K, PrFeB arrays monotonically increase performance with lower operating temperature. It opens up the posibility for use in operating a cryo-permanent magnet undulator (CPMU) in the range of 40K to 60K where very efficient cryocoolers are available. Magnetic flux density profiles were measured at various temperature ranges from room temperature down to liquid helium (LHe) usingmore » the Vertical Testing Facility (VTF) at the National Snchrotron Light Source-II (NSLS-II). Temperature variations of phase error have been characterized. In addition, we examined the use of textured Dysprosium (Dy) poles to replace permendur poles to obtain further improvement in performance.« less

High temperature thermometric phosphors

DOEpatents

Allison, Stephen W.; Cates, Michael R.; Boatner, Lynn A.; Gillies, George T.

1999-03-23

A high temperature phosphor consists essentially of a material having the general formula LuPO.sub.4 :Dy.sub.(x),Eu.sub.y) wherein: 0.1 wt %.ltoreq.x.ltoreq.20 wt % and 0.1 wt %.ltoreq.y.ltoreq.20 wt %. The high temperature phosphor is in contact with an article whose temperature is to be determined. The article having the phosphor in contact with it is placed in the environment for which the temperature of the article is to be determined. The phosphor is excited by a laser causing the phosphor to fluoresce. The emission from the phosphor is optically focused into a beam-splitting mirror which separates the emission into two separate emissions, the emission caused by the dysprosium dopant and the emission caused by the europium dopent. The separated emissions are optically filtered and the intensities of the emission are detected and measured. The ratio of the intensity of each emission is determined and the temperature of the article is calculated from the ratio of the intensities of the separate emissions.

High temperature thermometric phosphors

DOEpatents

Allison, S.W.; Cates, M.R.; Boatner, L.A.; Gillies, G.T.

1999-03-23

A high temperature phosphor consists essentially of a material having the general formula LuPO{sub 4}:Dy{sub x},Eu{sub y} wherein: 0.1 wt % {<=} x {<=} 20 wt % and 0.1 wt % {<=} y {<=} 20 wt %. The high temperature phosphor is in contact with an article whose temperature is to be determined. The article having the phosphor in contact with it is placed in the environment for which the temperature of the article is to be determined. The phosphor is excited by a laser causing the phosphor to fluoresce. The emission from the phosphor is optically focused into a beam-splitting mirror which separates the emission into two separate emissions, the emission caused by the dysprosium dopant and the emission caused by the europium dopant. The separated emissions are optically filtered and the intensities of the emission are detected and measured. The ratio of the intensity of each emission is determined and the temperature of the article is calculated from the ratio of the intensities of the separate emissions. 2 figs.

High temperature thermometric phosphors for use in a temperature sensor

DOEpatents

Allison, S.W.; Cates, M.R.; Boatner, L.A.; Gillies, G.T.

1998-03-24

A high temperature phosphor consists essentially of a material having the general formula LuPO{sub 4}:Dy{sub (x)},Eu{sub (y)}, wherein: 0.1 wt %{<=}x{<=}20 wt % and 0.1 wt %{<=}y{<=}20 wt %. The high temperature phosphor is in contact with an article whose temperature is to be determined. The article having the phosphor in contact with it is placed in the environment for which the temperature of the article is to be determined. The phosphor is excited by a laser causing the phosphor to fluoresce. The emission from the phosphor is optically focused into a beam-splitting mirror which separates the emission into two separate emissions, the emission caused by the dysprosium dopant and the emission caused by the europium dopant. The separated emissions are optically filtered and the intensities of the emission are detected and measured. The ratio of the intensity of each emission is determined and the temperature of the article is calculated from the ratio of the intensities of the separate emissions. 2 figs.

Thermoluminescence (TL) properties and x-ray diffraction (XRD) analysis of high purity CaSO4:Dy TL material

NASA Astrophysics Data System (ADS)

Kamarudin, Nadira; Abdullah, Wan Saffiey Wan; Hamid, Muhammad Azmi Abdul; Dollah, Mohd Taufik

2014-09-01

This paper presents the characterization and TL properties of dysprosium (Dy) doped calcium sulfate (CaSO4) TL material produced by co-precipitation technique with 0.5mol% concentration of dopant. The morphology of the produced TL material was studied using scanning electron microscope (SEM) and the micrograph shows that rectangular parallelepiped shaped crystal with the average of 150 μm in length were produced. The crystallinity of the produced powder was studied using x-ray powder diffraction (XRD). The XRD spectra show that the TL material produced is high purity anhydrite CaSO4 with average crystallite size of 74 nm with orthorhombic crystal system. The TL behavior of produced CaSO4:Dy was studied using a TLD reader after exposure to gamma ray by Co60 source with the doses of 1,5 and 10 Gy. The glow curve shows linear response with glow peak around 230°C which is desired development in the field of radiation dosimetry.

Two novel 2D lanthanide sulfate frameworks: Syntheses, structures, and luminescence properties

NASA Astrophysics Data System (ADS)

Li, Zhong-Yi; Zhang, Chi; Zhang, Fu-Li; Zhang, Fu-Qiang; Zhang, Xiang-Fei; Li, Su-Zhi; Cao, Guang-Xiu; Zhai, Bin

2016-03-01

Two novel lanthanide-sulfate compounds, [Ln2(SO4)3(H2O)8] (Ln = Tb (1) and Dy (2)), have been synthesized under hydrothermal reactions. X-ray crystal structure analyses reveal that 1 and 2 are isomorphous and crystallize in monoclinic C2/c pace group, showing a layered structure. The layers bear a rare quasi-honeycomb metal arrangement, which is fastened by μ3 = η1:η1:η1 and μ2 = η1:η1 sulfates. If assigning the μ3 = η1:η1:η1 sulfate as a 3-connected node and the Ln3+ ion as a 4-connected node, the network can be rationalized as a binodal (3,4)-connected V2O5 topology with a Schäfli symbol of (42·63·8) (42·6). In addition, the infrared, thermogravimetric analysis and luminescent properties were also studied. Complexes 1 and 2 exhibit outstanding thermal stability and characteristic terbium and dysprosium luminescence.

Modified Pechini's method to prepare LaAlO3:RE thermoluminescent materials

NASA Astrophysics Data System (ADS)

Rivera-Montalvo, T.; Morales-Hernandez, A.; Barrera-Angeles, A. A.; Alvarez-Romero, R.; Falcony, C.; Zarate-Medina, J.

2017-11-01

This work presents an alternative method to prepare rare-earth doped lanthanum aluminates materials for thermoluminescent (TL) dosimetry applications. Modified Pechini´s method was using to prepare praseodymium doped LaAlO3 powders. LaAlO3:Pr3+ powders were prepared using La(NO3)3·6H2O, Al(NO3)3·6H2O, Pr(NO3)3·6H2O, citric acid, and ethylene glycol. The solution was heated to 80 °C for its polyesterification reaction. The obtained powders were submitted at different thermal treatment from 700 up to 1600 °C. The structural and morphological characterizations were carried out using X-ray diffraction (XRD) and scanning electron microscopy techniques. TL glow curves of the X-ray irradiated samples showed one peak for europium and praseodymium dopants, meanwhile for powders doped with dysprosium ion showed two peaks. The technique is low cost, faster and it produces homogeneous particles can be used as thermoluminescent phosphors.

Economic assessment for recycling critical metals from hard disk drives using a comprehensive recovery process

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

Nguyen, Ruby Thuy; Diaz, Luis A.; Imholte, D. Devin

Since the 2011 price spike of rare earth elements (REEs), research on permanent magnet recycling has blossomed globally 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. However, current processes for recycling e-waste only focus on certain metals due to feedstock and metal price uncertainties. In addition, some believe that recycling REEs is unprofitable. To shed some light on the economic viability of REE recycling from HDDs, this paper combines techno-economic information of a hydrometallurgical process with end-of-life HDD availability in a simulation model.more » Results showed that adding REEs to HDD recycling was profitable given current prices. As a result, recovered REEs could meet up to 5.1% rest of world (excluding China) magnet demand. Aluminum, gold, copper scrap and REEs were the primary main revenue streams from HDD recycling.« less

Economic assessment for recycling critical metals from hard disk drives using a comprehensive recovery process

DOE PAGES

Nguyen, Ruby Thuy; Diaz, Luis A.; Imholte, D. Devin; ...

2017-06-05

Since the 2011 price spike of rare earth elements (REEs), research on permanent magnet recycling has blossomed globally 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. However, current processes for recycling e-waste only focus on certain metals due to feedstock and metal price uncertainties. In addition, some believe that recycling REEs is unprofitable. To shed some light on the economic viability of REE recycling from HDDs, this paper combines techno-economic information of a hydrometallurgical process with end-of-life HDD availability in a simulation model.more » Results showed that adding REEs to HDD recycling was profitable given current prices. As a result, recovered REEs could meet up to 5.1% rest of world (excluding China) magnet demand. Aluminum, gold, copper scrap and REEs were the primary main revenue streams from HDD recycling.« less

Pico-level DNA sensing by hetero-polymetalate, Na10{Dy2W10O30(µ-S)6}·80H2O, cluster

NASA Astrophysics Data System (ADS)

Dutta, Taposhree; Ganguly, Jhuma; Sarkar, Sabyasachi

2018-04-01

The polyoxometalate dysprosium cluster, (Dy-S-W POM) , Na10[Dy2W10O30(µ-S)6]·80H2O, shows remarkable dsDNA denaturation property. In the presence of 0.22 µmol of this Dy-S-W POM, the melting temperature (Tm) of calf-thymus (CT) dsDNA is decreased to 62.35 °C. Dy-S-W POM shows bleaching of methylene blue (MB). Addition of CT-DNA in the MB bleached solution of Dy-S-W POM apparently intercalates MB. Such trapped MB by CT-DNA responds to its re-oxidation by elemental sulfur formed in the bleaching process involving Dy-S-W POM. This reduction-oxidation property of MB with Dy-S-W POM led to the detection of pico (13.20 pmol) level of DNA even by naked eye, which will be helpful for rapid trace DNA detection in forensic science and DNA-related diagnostics, complimenting time-consuming sophisticated methodology.

Development and testing of passive tracking markers for different field strengths and tracking speeds.

PubMed

Peeters, J M; Seppenwoolde, J-H; Bartels, L W; Bakker, C J G

2006-03-21

Susceptibility markers for passive tracking need to be small in order to maintain the shape and mechanical properties of the endovascular device. Nevertheless, they also must have a high magnetic moment to induce an adequate artefact at a variety of scan techniques, tracking speeds and, preferably, field strengths. Paramagnetic markers do not satisfy all of these requirements. Ferro- and ferrimagnetic materials were therefore investigated with a vibrating sample magnetometer and compared with the strongly paramagnetic dysprosium oxide. Results indicated that the magnetic behaviour of stainless steel type AISI 410 corresponds the best with ideal marker properties. Markers with different magnetic moments were constructed and tested in in vitro and in vivo experiments. The appearance of the corresponding artefacts was field strength independent above magnetic saturation of 1.5 T. Generally, the contrast-to-noise ratio decreased at increasing tracking speed and decreasing magnetic moment. Device depiction was most consistent at a frame rate of 20 frames per second.

Synthesis and characteristic of polyaniline/Dy₂O₃ composites: Thermal property and electrochemical performance.

PubMed

Wang, Shaoxu; Li, Yan; Huang, Zihang; Li, Hui

2013-12-01

A simple route of in situ polymerization by the chemical oxidation method was successfully employed to synthesize polyaniline/dysprosium oxide (PANI/Dy2O3) composites. The synthesized materials were characterized by Fourier transform infrared spectra and X-ray diffraction. The thermal stability of the composite was studied by thermogravimetry (TG). The electrochemical performance of the composites was investigated by cyclic voltammetry and alternating current impedance spectroscopy with a three-electrode system. TG results suggested that the thermal stability of PANI/Dy2O3 composites showed a tendency to first increase and then decrease with increasing Dy2O3 amount. Electrochemical experiments indicated that the composite electrodes showed a lower capacitance than that of pure PANI, which may be attributed to the interaction between PANI and Dy2O3 in the composites. Copyright © 2013 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Selective Extraction and Recovery of Nd and Dy from Nd-Fe-B Magnet Scrap by Utilizing Molten MgCl2

NASA Astrophysics Data System (ADS)

Shirayama, Sakae; Okabe, Toru H.

2018-06-01

Fundamental experiments are conducted with the aim of developing an efficient recycling process for rare earth elements (REEs) from neodymium-iron-boron (Nd-Fe-B) permanent magnet scrap. Molten magnesium dichloride (MgCl2) was chosen as an extraction medium, which can selectively chlorinate and extract REEs in magnet alloys. Dysprosium-containing Nd-Fe-B magnet alloy was immersed in molten MgCl2 at 1273 K (1000 °C) for 3 to 12 hours. The results of the experiments clearly show that the REEs in the magnetic alloy were successfully extracted into the molten salt, while the Fe-B alloy remained in a solid form. The extraction ratios of Nd and Dy were at most 87 and 78 mass pct, respectively. After the extraction experiment, excess MgCl2 and Mg were removed by vacuum distillation and the rare earth chlorides were recovered. Thus, the feasibility of this method for efficient recovery of rare earths using molten MgCl2 is demonstrated.

Modeling the Value Recovery of Rare Earth Permanent Magnets at End-of-Life

DOE PAGES

Cong, Liang; Jin, Hongyue; Fitsos, Pete; ...

2015-05-21

Permanent magnets containing rare earth elements (REEs) such as Dysprosium and Neodymium offer an advantage over non-REE containing magnets (e.g. ferrite or AlNiCo) in terms of power relative to size. However, REE availability has varied significantly in recent years leading to volatility in the cost of rare earth permanent magnets (REPMs). The supply of REEs can be increased by recycling consumer products and industrial machinery that contain REPMs at product end-of-life (EOL). This paper discusses the REE recovery process for EOL products. The optimal dismantling of products is examined with an emphasis placed on obtaining used REPMs. The challenge ofmore » collecting, managing, transporting, and processing used products is addressed through the development of a cost model for REPM recovery. This model is used to investigate several EOL strategies for recovering REPMs. Sensitivity analysis is conducted to identify the key factors that influence value recovery economics. A hard disk drive serves as a case study for model demonstration.« less

Selfbound quantum droplets

NASA Astrophysics Data System (ADS)

Langen, Tim; Wenzel, Matthias; Schmitt, Matthias; Boettcher, Fabian; Buehner, Carl; Ferrier-Barbut, Igor; Pfau, Tilman

2017-04-01

Self-bound many-body systems are formed through a balance of attractive and repulsive forces and occur in many physical scenarios. Liquid droplets are an example of a self-bound system, formed by a balance of the mutual attractive and repulsive forces that derive from different components of the inter-particle potential. On the basis of the recent finding that an unstable bosonic dipolar gas can be stabilized by a repulsive many-body term, it was predicted that three-dimensional self-bound quantum droplets of magnetic atoms should exist. Here we report on the observation of such droplets using dysprosium atoms, with densities 108 times lower than a helium droplet, in a trap-free levitation field. We find that this dilute magnetic quantum liquid requires a minimum, critical number of atoms, below which the liquid evaporates into an expanding gas as a result of the quantum pressure of the individual constituents. Consequently, around this critical atom number we observe an interaction-driven phase transition between a gas and a self-bound liquid in the quantum degenerate regime with ultracold atoms.

Formation of dysprosium carbide on the graphite (0001) surface

DOE PAGES

Lii-Rosales, Ann; Zhou, Yinghui; Wallingford, Mark; ...

2017-07-12

When using scanning tunneling microscopy, we characterize a surface carbide that forms such that Dy is deposited on the basal plane of graphite. In order to form carbide islands on terraces, Dy is first deposited at 650–800 K, which forms large metallic islands. Upon annealing at 1000 K, these clusters convert to carbide. Deposition directly at 1000 K is ineffective because nucleation on terraces is inhibited. Reaction is signaled by the fact that each carbide cluster is partially or totally surrounded by an etch pit. The etch pit is one carbon layer deep for most carbide clusters. Carbide clusters aremore » also identifiable by striations on their surfaces. Based on mass balance, and assuming that only the surface layer of carbon is involved in the reaction, the carbide has stoichiometry D y 2 C . This is Dy-rich compared with the most common bulk carbide Dy C 2 , which may reflect limited surface carbon transport to the carbide.« less

Predictive model for ionic liquid extraction solvents for rare earth elements

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

Grabda, Mariusz; Oleszek, Sylwia; Institute of Environmental Engineering of the Polish Academy of Sciences, ul. M. Sklodowskiej-Curie 34, 41-819, Zabrze

2015-12-31

The purpose of our study was to select the most effective ionic liquid extraction solvents for dysprosium (III) fluoride using a theoretical approach. Conductor-like Screening Model for Real Solvents (COSMO-RS), based on quantum chemistry and the statistical thermodynamics of predefined DyF{sub 3}-ionic liquid systems, was applied to reach the target. Chemical potentials of the salt were predicted in 4,400 different ionic liquids. On the base of these predictions set of ionic liquids’ ions, manifesting significant decrease of the chemical potentials, were selected. Considering the calculated physicochemical properties (hydrophobicity, viscosity) of the ionic liquids containing these specific ions, the most effectivemore » extraction solvents for liquid-liquid extraction of DyF{sub 3} were proposed. The obtained results indicate that the COSMO-RS approach can be applied to quickly screen the affinity of any rare earth element for a large number of ionic liquid systems, before extensive experimental tests.« less

Selective Extraction and Recovery of Nd and Dy from Nd-Fe-B Magnet Scrap by Utilizing Molten MgCl2

NASA Astrophysics Data System (ADS)

Shirayama, Sakae; Okabe, Toru H.

2018-02-01

Fundamental experiments are conducted with the aim of developing an efficient recycling process for rare earth elements (REEs) from neodymium-iron-boron (Nd-Fe-B) permanent magnet scrap. Molten magnesium dichloride (MgCl2) was chosen as an extraction medium, which can selectively chlorinate and extract REEs in magnet alloys. Dysprosium-containing Nd-Fe-B magnet alloy was immersed in molten MgCl2 at 1273 K (1000 °C) for 3 to 12 hours. The results of the experiments clearly show that the REEs in the magnetic alloy were successfully extracted into the molten salt, while the Fe-B alloy remained in a solid form. The extraction ratios of Nd and Dy were at most 87 and 78 mass pct, respectively. After the extraction experiment, excess MgCl2 and Mg were removed by vacuum distillation and the rare earth chlorides were recovered. Thus, the feasibility of this method for efficient recovery of rare earths using molten MgCl2 is demonstrated.

Efficient enhancement of magnetic anisotropy by optimizing the ligand-field in a typically tetranuclear dysprosium cluster.

PubMed

Liu, Jiang; Chen, Yan-Cong; Jiang, Zhong-Xia; Liu, Jun-Liang; Jia, Jian-Hua; Wang, Long-Fei; Li, Quan-Wen; Tong, Ming-Liang

2015-05-07

The perturbation to the ligand field around the lanthanide ion may significantly contribute to the magnetic dynamics of single molecule magnets. This can be demonstrated by two typical Dy4 cluster-based single molecular magnets (SMMs), [Dy4X2(μ3-OH)2(μ-OH)2(2,2-bpt)4(H2O)4]X2·2H2O·4EtOH (X = Cl and Br for and , respectively), which were constructed by using 3,5-bis(pyridin-2-yl)-1,2,4-triazole (2,2-bptH) as the polynuclear-chelating ligand. Alternating-current (ac) magnetic susceptibility measurements show that the energy barriers in complexes and were immensely enhanced by comparing with our previous work due to the optimization of the ligand field around Dy(III) ions. Remarkably, their high thermal active barriers at 190 K () and 197 K () under a zero applied external dc magnetic field are also among the highest within the reported tetranuclear lanthanide-based SMMs.

Levels in 227Ac populated in the 230Th( p, α) reaction

NASA Astrophysics Data System (ADS)

Burke, D. G.; Garrett, P. E.; Qu, Tao

2003-09-01

The 230,232Th(p, α) 227,229Ac reactions were studied using 20 MeV protons and a magnetic spectrograph to analyze the reaction products. Relative populations of levels in 229Ac correlated well with previously published (t, α) results for the same final levels, showing that the similarity of the two reactions observed empirically in the deformed rare earth region extends to actinides. The most strongly populated level in 227Ac is at 639 keV, and is assigned as the 1/2 +[4 0 0] bandhead. The 435 keV level, previously adopted as the 1/2 +[6 6 0] bandhead, also has a significant intensity that is attributed to Δ N=2 mixing between these two K=1/2 proton orbitals. The Δ N=2 matrix element estimated from these data is ˜80 keV, similar to values observed for the same two Nilsson states as neutron orbitals in the dysprosium isotopes.

Two Series of Homodinuclear Lanthanide Complexes: Greatly Enhancing Energy Barriers through Tuning Terminal Solvent Ligands in Dy2 Single-Molecule Magnets.

PubMed

Qin, Yaru; Zhang, Haifeng; Sun, Hao; Pan, Yangdan; Ge, Yu; Li, Yahong; Zhang, Yi-Quan

2017-11-02

The utilization of 2-ethoxy-6-{[(2-hydroxy-3-methoxybenzyl)imino]methyl}phenol (H 2 L) as a chelating ligand, in combination with the employment of alcohols (EtOH and MeOH) as auxiliary ligands, in 4 f-metal chemistry afforded two series of dinuclear lanthanide complexes of compositions [Ln 2 L 2 (NO 3 ) 2 (EtOH) 2 ] (Ln=Sm (1), Eu (2), Gd (3), Tb (4), Dy (5), Ho (6), Er (7)) and [Ln 2 L 2 (NO 3 ) 2 (MeOH) 2 ] (Ln=Sm (8), Eu (9), Gd (10), Tb (11), Dy (12), Ho (13), Er (14)). The structures of 1-14 were determined by single-crystal X-ray crystallography. Complexes 1-7 are isomorphous. The two lanthanide(III) ions in 1-7 are doubly bridged by two deprotonated aminophenoxide oxygen atoms of two μ 2 :η 0 :η 1 :η 2 :η 1 :η 1 :η 0 -L 2- ligands. One nitrogen atom, two oxygen atoms of the NO 3 - anion, two methoxide oxygen atoms of two ligand sets, and one oxygen atom of the terminally coordinated EtOH molecule complete the distorted dodecahedron geometry of each lanthanide(III) ion. Compounds 8-14 are isomorphous and their structures are similar to those of 1-7. The slight difference between 1-7 and 8-14 stems from purposefully replacing the EtOH ligands in 1-7 with MeOH in 8-14. Direct-current magnetic susceptibility studies in the 2-300 K range reveal weak antiferromagnetic interactions for 3, 4, 7, 10, 11, and 14, and ferromagnetic interactions at low temperature for 5, 6, 12, and 13. Complexes 5 and 12 exhibit single-molecule magnet (SMM) behavior with energy barriers of 131.3 K for 5 and 198.8 K for 12. The energy barrier is significantly enhanced by dexterously regulating the terminal ligands. To rationalize the observed difference in the magnetic behavior, complete-active-space self-consistent field (CASSCF) calculations were performed on two Dy 2 complexes. Subtle variation in the angle between the magnetic axes and the vector connecting two dysprosium(III) ions results in a weaker influence on the tunneling gap of individual dysprosium(III) ions by the dipolar field in 12. This work proposes an efficient strategy for synthesizing Dy 2 SMMs with high energy barriers. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Methods and computer executable instructions for marking a downhole elongate line and detecting same

DOEpatents

Watkins, Arthur D.

2003-05-13

Methods and computer executable instructions are provided for making an elongate line (22) with a plurality of marks (30) and detecting those marks (30) to determine a distance of the elongate line (22) in a downhole or a physical integrity thereof. In a preferred embodiment, each mark comprises a plurality of particles (44) having a substantially permanent magnetizing capability adhered to an exterior surface of the elongate line (22) at preselected intervals with an epoxy paint. The particles (44) are arranged at each interval as a plurality of bands (40). Thereafter, the particles are oriented into a magnetic signature for that interval by magnetizing the particles to create a magnetic field substantially normal to the exterior surface. This facilitates detection by a Hall effect probe. The magnetic signatures are stored in a computing configuration and, once a mark is detected, a correlation is made to a unique position on the elongate line by comparison with the stored magnetic signatures. Preferred particles include samarium-cobalt and neodymium-iron-boride.

Stability of Ceramics in Hydrogen between 4000 and 4500 F

NASA Technical Reports Server (NTRS)

May, Charles E.; Koneval, Donald; Fryburg, George C.

1959-01-01

The various reactions that are possible between hydrogen and certain ceramic materials are discussed as well as the means of measuring the extent of such reactions. Powdered carbides, nitrides, borides, and oxides were tested. These materials were heated inductively in a tungsten cup between 4000 and 4500 F for two 1-hour periods under a static hydrogen atmosphere. Weight, pressure, and diffraction pattern changes were observed, and these served to indicate the extent of reaction. Most of the ceramics, HfC, ZrC, TiC, TaC, NbC, WC, MO2C, HfN, ZrN, NbN, ZrB2, NbB2, and WB, showed less reaction than the minimum detectable value. However, the ceramics, TiN, TaN, HfB2, TiB2, ZrO2, and Cr2O3, apparently reacted to a measurable extent with hydrogen. Reactions of SiC, VC, and TaB2 with hydrogen were not determinable because of their incompatibility with the tungsten container.

Axial residual stresses in boron fibers

NASA Technical Reports Server (NTRS)

Behrendt, D. R.

1978-01-01

The axial residual stress distribution as a function of radius was determined from the fiber surface to the core including the average residual stress in the core. Such measurements on boron on tungsten (B/W) fibers show that the residual stresses for 102, 142, 203, and 366 micron diameter fibers were similar, being compressive at the surface and changing monotonically to a region of tensile within the boron. At approximately 25 percent of the original radius, the stress reaches a maximum tensile stress of about 860 mn/sq.m and then decreases to a compressive stress near the tungsten boride core. Data were presented for 203 micron diameter B/W fibers that show annealing above 900 C reduces the residual stresses. A comparison between 102 micron diameter B/W and boron on carbon (b/C) shows that the residual stresses were similar in the outer regions of the fibers, but that large differences near and in the core were observed. The effects of these residual stresses on the fracture of boron fibers were discussed.

Manganese mono-boride, an inexpensive room temperature ferromagnetic hard material

PubMed Central

Ma, Shuailing; Bao, Kuo; Tao, Qiang; Zhu, Pinwen; Ma, Teng; Liu, Bo; Liu, Yazhou; Cui, Tian

2017-01-01

We synthesized orthorhombic FeB-type MnB (space group: Pnma) with high pressure and high temperature method. MnB is a promising soft magnetic material, which is ferromagnetic with Curie temperature as high as 546.3 K, and high magnetization value up to 155.5 emu/g, and comparatively low coercive field. The strong room temperature ferromagnetic properties stem from the positive exchange-correlation between manganese atoms and the large number of unpaired Mn 3d electrons. The asymptotic Vickers hardness (AVH) is 15.7 GPa which is far higher than that of traditional ferromagnetic materials. The high hardness is ascribed to the zigzag boron chains running through manganese lattice, as unraveled by X-ray photoelectron spectroscopy result and first principle calculations. This exploration opens a new class of materials with the integration of superior mechanical properties, lower cost, electrical conductivity, and fantastic soft magnetic properties which will be significant for scientific research and industrial application as advanced structural and functional materials. PMID:28262805

Laser-assisted selective fusing of thermal sprayed Ni-based self-fluxing alloys by using high-power diode lasers

NASA Astrophysics Data System (ADS)

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

2018-03-01

Fusing treatment of Ni-based self-fluxing alloys (Metco-16C and 1276F) was performed using high-power diode lasers to control the temperature of the substrate's surface in real time. The effects of the fusing treatment temperature on the microstructural change and hardness distribution were also investigated. For Metco-16C and 1276F, the macrostructural inhomogeneity (voids) within the thermal sprayed layer decreased considerably as the fusing temperature increased. For both self-fluxing alloys, the optimal temperature for fusing was approximately 1423 K (for Metco-16C) and 1373 K (for 1276F), both of which are within the solid state temperature range; these temperatures maximize the alloy hardness together with the macrostructural homogeneity. In this temperature range, the microstructure consists of a lamellar-structured matrix phase with fine (<5 μm) carbides and borides. Selective fusing for a thermal sprayed layer 0.2-0.5 mm in thickness could be successfully achieved in a high-power diode laser system.

Effect of In-Situ Titanium Boride Particle Addition and Friction Stir Processing on Wear Behavior of Aluminum Alloy 2219

NASA Astrophysics Data System (ADS)

Sampath, V.; Rajasekaran, N. R.

There is paucity of data on the effect of in-situ TiB2 particles on the different behavior of 2219 Al alloy. In the present work, therefore, composites with 2219 Al alloy matrix reinforced with in-situ TiB2 particles were produced by flux-assisted synthesis. Different amounts (5 and 10 wt.%) of TiB2 were incorporated. The base alloy and the composites were subjected to friction stir processing to reduce particle clustering. The wear behavior of the materials was studied. The base alloy showed considerable improvement in the wear behavior due to the in-situ particle addition which is attributed to the presence of finer particles with good interfacial bonding and high hardness. Uniform distribution of TiB2 particles and good interface between the matrix and the particles led to reduction in the wear of friction stir processed composites by 30%. The results are analyzed and discussed in detail in the paper.

Tungsten tetraboride, an inexpensive superhard material

PubMed Central

Mohammadi, Reza; Lech, Andrew T.; Xie, Miao; Weaver, Beth E.; Yeung, Michael T.; Tolbert, Sarah H.; Kaner, Richard B.

2011-01-01

Tungsten tetraboride (WB4) is an interesting candidate as a less expensive member of the growing group of superhard transition metal borides. WB4 was successfully synthesized by arc melting from the elements. Characterization using powder X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX) indicates that the as-synthesized material is phase pure. The zero-pressure bulk modulus, as measured by high-pressure X-ray diffraction for WB4, is 339 GPa. Mechanical testing using microindentation gives a Vickers hardness of 43.3 ± 2.9 GPa under an applied load of 0.49 N. Various ratios of rhenium were added to WB4 in an attempt to increase hardness. With the addition of 1 at.% Re, the Vickers hardness increased to approximately 50 GPa at 0.49 N. Powders of tungsten tetraboride with and without 1 at.% Re addition are thermally stable up to approximately 400 °C in air as measured by thermal gravimetric analysis. PMID:21690363

Microstructural Response of Directionally Solidified René 80 Superalloy to Gas-Tungsten Arc Welding

NASA Astrophysics Data System (ADS)

Sidhu, R. K.; Ojo, O. A.; Chaturvedi, M. C.

2009-01-01

The microstructural response of directionally solidified René 80 (DS René 80) superalloy to gas-tungsten-arc (GTA) welding was investigated. Rapid heating during welding resulted in a significant grain-boundary liquation of solid-state reaction product γ' precipitates, intergranular elemental segregation induced M5B3 borides, and secondary solidification constituents MC carbides and sulfocarbides, which were all present in the preweld heat-treated alloy. Liquation of these particles embrittled the grain boundaries in the heat-affected zone (HAZ) and caused microfissuring along the liquated grain boundaries. Nevertheless, contrary to the generally observed increase in HAZ cracking in superalloys with an increase in Ti and Al concentration, due to increase in the alloy’s hardness, significantly reduced cracking was observed in DS René 80 compared to the conventionally cast IN738 welded under the same conditions, despite its hardness being higher than that of IN738. This was related to the nature of base-metal grain- boundary intersections at the fusion-zone boundary in these materials.

A Plasma Reactor for the Synthesis of High-Temperature Materials: Electro Thermal, Processing and Service Life Characteristics

NASA Astrophysics Data System (ADS)

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

2016-08-01

The three-jet direct-flow plasma reactor with a channel diameter of 0.054 m was studied in terms of service life, thermal, technical, and functional capabilities. It was established that the near-optimal combination of thermal efficiency, required specific enthalpy of the plasma-forming gas and its mass flow rate is achieved at a reactor power of 150 kW. The bulk temperature of plasma flow over the rector of 12 gauges long varies within 5500÷3200 K and the wall temperature within 1900÷850 K, when a cylinder from zirconium dioxide of 0.005 m thick is used to thermally insulate the reactor. The specific electric power reaches a high of 1214 MW/m3. The rated service life of electrodes is 4700 hours for a copper anode and 111 hours for a tungsten cathode. The projected contamination of carbides and borides with elec-trode-erosion products doesn't exceed 0.0001% of copper and 0.00002% of tungsten.

Ab initio Computations of the Electronic, Mechanical, and Thermal Properties of Ultra High Temperature Ceramics (UHTC) ZrB2 and HfB2

NASA Technical Reports Server (NTRS)

Lawson, John W.; Bauschlicher, Charles W.; Daw, Murray

2011-01-01

Refractory materials such as metallic borides, often considered as ultra high temperature ceramics (UHTC), are characterized by high melting point, high hardness, and good chemical inertness. These materials have many applications which require high temperature materials that can operate with no or limited oxidation. Ab initio, first principles methods are the most accurate modeling approaches available and represent a parameter free description of the material based on the quantum mechanical equations. Using these methods, many of the intrinsic properties of these material can be obtained. We performed ab initio calculations based on density functional theory for the UHTC materials ZrB2 and HfB2. Computational results are presented for structural information (lattice constants, bond lengths, etc), electronic structure (bonding motifs, densities of states, band structure, etc), thermal quantities (phonon spectra, phonon densities of states, specific heat), as well as information about point defects such as vacancy and antisite formation energies.

Physical and technological principles of designing layer-gradient multicomponent surfaces by combining the methods of ion-diffusion saturation and magnetron- and vacuum-arc deposition

NASA Astrophysics Data System (ADS)

Savostikov, V. M.; Potekaev, A. I.; Tabachenko, A. N.

2011-12-01

Using a technological system proposed by the authors, a combined process is developed for formation of stratified-gradient surface layers and multicomponent coatings. It is implemented under the conditions of a combined serial-parallel operation of a hot-cathode gas plasma generator and a duomagnetron with two targets and two electric-arc evaporators. The extended functional potential is ensured by using advanced multi-element and multi-phase cathode targets made of borides, carbides, silicides, and sulfides of metals produced by the SHS-process followed by their immediate compaction. The variations in composition, structure, and physicomechanical properties in the cross-section of the stratified-gradient surface layers and coating is provided by a predetermined alternating replacement of the sputtered cathode targets of the plasma sources, the plasma flow intensity ratios, and variation in the particle energy incident on the substrate, which is determined by the accelerating voltage on the substrate.

Synthesis and characterization of MoB{sub 2−x} thin films grown by nonreactive DC magnetron sputtering

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

Malinovskis, Paulius, E-mail: paulius.malinovskis@kemi.uu.se; Lewin, Erik; Jansson, Ulf

2016-05-15

DC magnetron sputtering was used to deposit molybdenum boride thin films for potential low-friction applications. The films exhibit a nanocomposite structure with ∼10 nm large MoB{sub 2−x} (x > 0.4) grains surrounded by a boron-rich tissue phase. The preferred formation of the metastable and substoichiometric hP3-MoB{sub 2} structure (AlB{sub 2}-type) is explained with kinetic constraints to form the thermodynamically stable hR18-MoB{sub 2} phase with a very complex crystal structure. Nanoindentation revealed a relatively high hardness of (29 ± 2) GPa, which is higher than bulk samples. The high hardness can be explained by a hardening effect associated with the nanocomposite microstructure where the surrounding tissuemore » phase restricts dislocation movement. A tribological study confirmed a significant formation of a tribofilm consisting of molybdenum oxide and boron oxide, however, without any lubricating effects at room temperature.« less

Oxidation resistant Mo-Mo2B-silica and Mo-Mo2B-silicate composites for high temperature applications

NASA Astrophysics Data System (ADS)

Cochran, J. K.; Daloz, W. L.; Marshall, P. E.

2011-12-01

Development of Mo composites based on the Mo-Si-B system has been demonstrated as a possible new route to achieving a high temperature Mobased material. In this new system, the silicide phases are replaced directly with silica or other silicate materials. These composites avoid the high ductile to brittle transition temperature observed for Mo-Si-B alloys by removing the Si that exists in solid solution in Mo at equilibrium with its silicides. A variety of compositions is tested for room temperature ductility and oxidation resistance. A system based upon Mo, Mo2B, and SrO·Al2O3·(SiO2)2 is shown to possess both ductility at 80 vol.% Mo and oxidation resistance at 60 vol.%. These composites can be produced using a powder processing approach and fired to greater than 95% theoretical density with a desirable microstructure of isolated boride and silicate phases within a ductile Mo matrix.

Fine Structure Study of the Plasma Coatings B4C-Ni-P

NASA Astrophysics Data System (ADS)

Kornienko, E. E.; Bezrukova, V. A.; Kuz'min, V. I.; Lozhkin, V. S.; Tutunkova, M. K.

2017-12-01

The article considers structure of coatings formed of the B4C-Ni-P powder. The coatings were deposited using air-plasma spraying with the unit for annular injection of powder. The pipes from steel 20 (0.2 % C) were used as a substrate. The structure and phase composition of the coatings were studied by optical microscopy, scanning electron microscopy, transmission electron microscopy and X-ray diffractometry. It is shown that high-density composite coatings consisting of boron carbide particles distributed in the nickel boride metal matrix are formed using air-plasma spraying. The areas with round inclusions characterized by the increased amount of nickel, phosphorus and boron are located around the boron carbide particles. Boron oxides and nickel oxides are also present in the coatings. Thin interlayers with amorphous-crystalline structure are formed around the boron carbide particles. The thickness of these interlayers does not exceed 1 μm. The metal matrix material represents areas with nanocrystalline structure and columnar crystals.

Conventional magnetic superconductors

DOE PAGES

Wolowiec, C. T.; White, B. D.; Maple, M. B.

2015-07-01

We discuss several classes of conventional magnetic superconductors including the ternary rhodium borides and molybdenum chalcogenides (or Chevrel phases), and the quaternary nickel-borocarbides. These materials exhibit some exotic phenomena related to the interplay between superconductivity and long-range magnetic order including: the coexistence of superconductivity and antiferromagnetic order; reentrant and double reentrant superconductivity, magnetic field induced superconductivity, and the formation of a sinusoidally-modulated magnetic state that coexists with superconductivity. We introduce the article with a discussion of the binary and pseudobinary superconducting materials containing magnetic impurities which at best exhibit short-range “glassy” magnetic order. Early experiments on these materials led tomore » the idea of a magnetic exchange interaction between the localized spins of magnetic impurity ions and the spins of the conduction electrons which plays an important role in understanding conventional magnetic superconductors. Furthermore, these advances provide a natural foundation for investigating unconventional superconductivity in heavy-fermion compounds, cuprates, and other classes of materials in which superconductivity coexists with, or is in proximity to, a magnetically-ordered phase.« less

Application of perturbation theory to lattice calculations based on method of cyclic characteristics

NASA Astrophysics Data System (ADS)

Assawaroongruengchot, Monchai

Perturbation theory is a technique used for the estimation of changes in performance functionals, such as linear reaction rate ratio and eigenvalue affected by small variations in reactor core compositions. Here the algorithm of perturbation theory is developed for the multigroup integral neutron transport problems in 2D fuel assemblies with isotropic scattering. The integral transport equation is used in the perturbative formulation because it represents the interconnecting neutronic systems of the lattice assemblies via the tracking lines. When the integral neutron transport equation is used in the formulation, one needs to solve the resulting integral transport equations for the flux importance and generalized flux importance functions. The relationship between the generalized flux importance and generalized source importance functions is defined in order to transform the generalized flux importance transport equations into the integro-differential equations for the generalized adjoints. Next we develop the adjoint and generalized adjoint transport solution algorithms based on the method of cyclic characteristics (MOCC) in DRAGON code. In the MOCC method, the adjoint characteristics equations associated with a cyclic tracking line are formulated in such a way that a closed form for the adjoint angular function can be obtained. The MOCC method then requires only one cycle of scanning over the cyclic tracking lines in each spatial iteration. We also show that the source importance function by CP method is mathematically equivalent to the adjoint function by MOCC method. In order to speed up the MOCC solution algorithm, a group-reduction and group-splitting techniques based on the structure of the adjoint scattering matrix are implemented. A combined forward flux/adjoint function iteration scheme, based on the group-splitting technique and the common use of a large number of variables storing tracking-line data and exponential values, is proposed to reduce the computing time when both direct and adjoint solutions are required. A problem that arises for the generalized adjoint problem is that the direct use of the negative external generalized adjoint sources in the adjoint solution algorithm results in negative generalized adjoint functions. A coupled flux biasing/decontamination scheme is applied to make the generalized adjoint functions positive using the adjoint functions in such a way that it can be used for the multigroup rebalance technique. Next we consider the application of the perturbation theory to the reactor problems. Since the coolant void reactivity (CVR) is a important factor in reactor safety analysis, we have decided to select this parameter for optimization studies. We consider the optimization and adjoint sensitivity techniques for the adjustments of CVR at beginning of burnup cycle (BOC) and k eff at end of burnup cycle (EOC) for a 2D Advanced CANDU Reactor (ACR) lattice. The sensitivity coefficients are evaluated using the perturbation theory based on the integral transport equations. Three sets of parameters for CVR-BOC and keff-EOC adjustments are studied: (1) Dysprosium density in the central pin with Uranium enrichment in the outer fuel rings, (2) Dysprosium density and Uranium enrichment both in the central pin, and (3) the same parameters as in the first case but the objective is to obtain a negative checkerboard CVR at beginning of cycle (CBCVR-BOC). To approximate the sensitivity coefficient at EOC, we perform constant-power burnup/depletion calculations for 600 full power days (FPD) using a slightly perturbed nuclear library and the unperturbed neutron fluxes to estimate the variation of nuclide densities at EOC. Sensitivity analyses of CVR and eigenvalue are included in the study. In addition the optimization and adjoint sensitivity techniques are applied to the CBCVR-BOC and keff-EOC adjustment of the ACR lattices with Gadolinium in the central pin. Finally we apply these techniques to the CVR-BOC, CVR-EOC and keff-EOC adjustment of a CANDU lattice of which the burnup period is extended from 300 to 450 FPDs. The cases with the central pin containing either Dysprosium or Gadolinium in the natural Uranium are considered in our study. (Abstract shortened by UMI.)

Design of Modern High Nb-Content gamma-gamma' Ni-Base Superalloys

NASA Astrophysics Data System (ADS)

Antonov, Stoichko

Certain elemental additions to Ni-base superalloys can significantly improve properties when added in high contents, but can quickly deteriorate the high temperature structural integrity and stability of the alloy, when solubility limits are exceeded and secondary phases are formed. Improved understanding of solubility limits of various elements in high refractory content Ni-base supralloys is therefore essential to improved alloy design. The morphology, formation, and composition of precipitate phases in a number of experimental alloys spanning a broad range of compositions were explored and compositional relationships were developed. The effect of increasing Nb alloying additions on formation and long term stability of topologically close packed (TCP) phases, as well as assessment of grain boundary phase compositions and local segregation along it before and after a 1000 hour thermal exposure at 800°C, was studied via electron microscopy and atom probe tomography (APT). Beneficial secondary phase precipitation, such as carbides and borides, was also studied through B, Hf and C doping. Elemental boron was observed to segregate to the grain boundary and phase interfaces, but did not form borides. APT studies on MC carbides of the alloys revealed the formation kinetics and morphological differences between NbC and Hf doped NbC, which were further explained using density functional theory (DFT) calculations of the formation energies of different facets of the MC carbide. Detailed electron microscopy and APT techniques were then used to systematically quantify the chemical and morphological instabilities that occur during aging of polycrystalline γ-γ' Ni-base superalloys containing elevated levels of refractory alloying additions. The morphological changes and splitting phenomenon associated with the secondary γ' precipitates were related to the discrete chemical compositions of the secondary and tertiary γ' along with the phase compositions of the γ matrix and the γ precipitates that form within the secondary γ' particles. In addition, compositions of the constituent phases were measured in four high Nb-content γ-γ' Ni-base superalloys and the results were compared to thermodynamic database models from Thermo-Calc. Results were also used to predict the solid solution strength behavior of the four alloys. Finally, creep behavior of high Nb-content γ-γ' Ni-Based superalloys was related to the formation of secondary phases mainly at grain boundaries. As secondary phases form, their brittle nature leads to crack formation, which can propagate under the tensile load and lead to premature failure of the alloy.

Magnetic blocking in a linear iron(I) complex.

PubMed

Zadrozny, Joseph M; Xiao, Dianne J; Atanasov, Mihail; Long, Gary J; Grandjean, Fernande; Neese, Frank; Long, Jeffrey R

2013-07-01

Single-molecule magnets that contain one spin centre may represent the smallest possible unit for spin-based computational devices. Such applications, however, require the realization of molecules with a substantial energy barrier for spin inversion, achieved through a large axial magnetic anisotropy. Recently, significant progress has been made in this regard by using lanthanide centres such as terbium(III) and dysprosium(III), whose anisotropy can lead to extremely high relaxation barriers. We contend that similar effects should be achievable with transition metals by maintaining a low coordination number to restrict the magnitude of the d-orbital ligand-field splitting energy (which tends to hinder the development of large anisotropies). Herein we report the first two-coordinate complex of iron(I), [Fe(C(SiMe3)3)2](-), for which alternating current magnetic susceptibility measurements reveal slow magnetic relaxation below 29 K in a zero applied direct-current field. This S =  complex exhibits an effective spin-reversal barrier of Ueff = 226(4) cm(-1), the largest yet observed for a single-molecule magnet based on a transition metal, and displays magnetic blocking below 4.5 K.

Magnetostrictive Vibration Damper and Energy Harvester for Rotating Machinery

NASA Technical Reports Server (NTRS)

Deng, Zhangxian; Asnani, Vivake M.; Dapino, Marcelo J.

2015-01-01

Vibrations generated by machine driveline components can cause excessive noise and structural damage. Magnetostrictive materials, including Galfenol (iron-gallium alloys) and Terfenol-D (terbium-iron-dysprosium alloys), are able to convert mechanical energy to magnetic energy. A magnetostrictive vibration ring is proposed, which generates electrical energy and dampens vibration, when installed in a machine driveline. A 2D axisymmetric finite element (FE) model incorporating magnetic, mechanical, and electrical dynamics is constructed in COMSOL Multiphysics. Based on the model, a parametric study considering magnetostrictive material geometry, pickup coil size, bias magnet strength, flux path design, and electrical load is conducted to maximize loss factor and average electrical output power. By connecting various resistive loads to the pickup coil, the maximum loss factors for Galfenol and Terfenol-D due to electrical energy loss are identified as 0.14 and 0.34, respectively. The maximum average electrical output power for Galfenol and Terfenol-D is 0.21 W and 0.58 W, respectively. The loss factors for Galfenol and Terfenol-D are increased to 0.59 and 1.83, respectively, by using an L-C resonant circuit.

Photodissociation spectroscopy of the dysprosium monochloride molecular ion

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

Dunning, Alexander, E-mail: alexander.dunning@gmail.com; Schowalter, Steven J.; Puri, Prateek

2015-09-28

We have performed a combined experimental and theoretical study of the photodissociation cross section of the molecular ion DyCl{sup +}. The photodissociation cross section for the photon energy range 35 500 cm{sup −1} to 47 500 cm{sup −1} is measured using an integrated ion trap and time-of-flight mass spectrometer; we observe a broad, asymmetric profile that is peaked near 43 000 cm{sup −1}. The theoretical cross section is determined from electronic potentials and transition dipole moments calculated using the relativistic configuration-interaction valence-bond and coupled-cluster methods. The electronic structure of DyCl{sup +} is extremely complex due to the presence of multiple open electronic shells,more » including the 4f{sup 10} configuration. The molecule has nine attractive potentials with ionically bonded electrons and 99 repulsive potentials dissociating to a ground state Dy{sup +} ion and Cl atom. We explain the lack of symmetry in the cross section as due to multiple contributions from one-electron-dominated transitions between the vibrational ground state and several resolved repulsive excited states.« less

Dysprosium-doped PbGa2S4 laser generating at 4.3 μm directly pumped by 1.7 μm laser diode.

PubMed

Jelínková, Helena; Doroshenko, Maxim E; Jelínek, Michal; Sulc, Jan; Osiko, Vyacheslav V; Badikov, Valerii V; Badikov, Dmitrii V

2013-08-15

In this Letter, we demonstrate the pulsed and CW operation of the Dy:PbGa(2)S(4) laser directly pumped by the 1.7 μm laser diode. In the pulsed regime (pulse duration 5 ms; repetition rate 20 Hz), the maximum mean output power of 9.5 mW was obtained with the slope efficiency of 9.3% with respect to the absorbed pump power. The generated wavelength was 4.32 μm, and the laser beam cross section was approximately Gaussian on both axes. Stable CW laser generation was also successfully obtained with the maximum output power of 67 mW and the slope efficiency of 8%. Depopulation of the lower laser level by 1.7 μm pump radiation absorption followed by 1.3 μm upconversion fluorescence was demonstrated. These results show the possibility of construction of the compact diode-pumped solid-state pulsed or CW laser generating at 4.3 μm in the power level of tens mW operating at room temperature.

Thermoluminescence (TL) properties and x-ray diffraction (XRD) analysis of high purity CaSO{sub 4}:Dy TL material

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

Kamarudin, Nadira; Abdullah, Wan Saffiey Wan; Dollah, Mohd Taufik

2014-09-03

This paper presents the characterization and TL properties of dysprosium (Dy) doped calcium sulfate (CaSO{sub 4}) TL material produced by co-precipitation technique with 0.5mol% concentration of dopant. The morphology of the produced TL material was studied using scanning electron microscope (SEM) and the micrograph shows that rectangular parallelepiped shaped crystal with the average of 150 μm in length were produced. The crystallinity of the produced powder was studied using x-ray powder diffraction (XRD). The XRD spectra show that the TL material produced is high purity anhydrite CaSO{sub 4} with average crystallite size of 74 nm with orthorhombic crystal system. Themore » TL behavior of produced CaSO{sub 4}:Dy was studied using a TLD reader after exposure to gamma ray by Co{sup 60} source with the doses of 1,5 and 10 Gy. The glow curve shows linear response with glow peak around 230°C which is desired development in the field of radiation dosimetry.« less

Impact of neutron irradiation on the structural and optical properties of PVP/gelatin blends doped with dysprosium (III) chloride

NASA Astrophysics Data System (ADS)

Basha, Ahmad Fouad; Basha, Mohammad Ahmad-Fouad

2017-12-01

Polymer composites of a system of Polyvinylpyrrolidone (PVP)/gelatin/DyCl3.6H2O were prepared in three groups that have different concentrations of PVP/gelatin contents to study the effect of neutron irradiation on their structural and optical properties. Results showed that the interaction of neutrons led to various complex phenomena, mainly bond breaking, main chain scission and intermolecular cross-linking. These processes introduced defects inside the material that were responsible for the changes in their optical and structural properties. All the calculated parameters were found to be dependent on the irradiation fluence in a uniform manner that makes these materials excellent candidates in the applications of dosimetry and radiology. Moreover, the sensitivity of the three groups of composites to the irradiation doses was found to be different. The variation in the structure of the composite group that contains the least PVP content was found to be less significant; hence, these materials were more stable against high doses that make them suitable for high radiation dose applications.

Cryogenic Field Measurement of Pr{sub 2}Fe{sub 14}B Undulator and Performance Enhancement Options at the NSLS-II

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

Tanabe, Toshiya; Chubar, Oleg; Harder, David A.

2010-06-23

Short period (14.5mm) hybrid undulator arrays composed of Praseodymium Iron Boron (Pr{sub 2}Fe{sub 14}B) magnets (CR53, NEOMAX, Inc.) and vanadium permendur poles have been fabricated at Brookhaven National Laboratory. Unlike Neodymium Iron Boron (Nd{sub 2}Fe{sub 14}B) magnets which exhibit spin reorientation at a temperatures below 150 K, PrFeB arrays monotonically increase performance with lower operating temperature. It opens up the possibility for use in operating a cryo-permanent magnet undulator (CPMU) in the range of 40 K to 60 K where very efficient cryocoolers are available. Magnetic flux density profiles were measured at various temperature ranges from room temperature down tomore » liquid helium (LHe) using the Vertical Testing Facility (VTF) at the National Synchrotron Light Source-II (NSLS-II). Temperature variations of phase error have been characterized. In addition, we examined the use of textured Dysprosium (Dy) poles to replace permendur poles to obtain further improvement in performance.« less

Dysprosium sorption by polymeric composite bead: robust parametric optimization using Taguchi method.

PubMed

Yadav, Kartikey K; Dasgupta, Kinshuk; Singh, Dhruva K; Varshney, Lalit; Singh, Harvinderpal

2015-03-06

Polyethersulfone-based beads encapsulating di-2-ethylhexyl phosphoric acid have been synthesized and evaluated for the recovery of rare earth values from the aqueous media. Percentage recovery and the sorption behavior of Dy(III) have been investigated under wide range of experimental parameters using these beads. Taguchi method utilizing L-18 orthogonal array has been adopted to identify the most influential process parameters responsible for higher degree of recovery with enhanced sorption of Dy(III) from chloride medium. Analysis of variance indicated that the feed concentration of Dy(III) is the most influential factor for equilibrium sorption capacity, whereas aqueous phase acidity influences the percentage recovery most. The presence of polyvinyl alcohol and multiwalled carbon nanotube modified the internal structure of the composite beads and resulted in uniform distribution of organic extractant inside polymeric matrix. The experiment performed under optimum process conditions as predicted by Taguchi method resulted in enhanced Dy(III) recovery and sorption capacity by polymeric beads with minimum standard deviation. Copyright © 2015 Elsevier B.V. All rights reserved.

Study on the Structural, Morphological and Optical Properties of RF-Sputtered Dysprosium-Doped Barium Tungstate Thin Films

NASA Astrophysics Data System (ADS)

Hridya, S.; Kavitha, V. S.; Chalana, S. R.; Reshmi Krishnan, R.; Sreeja Sreedharan, R.; Suresh, S.; Nampoori, V. P. N.; Sankararaman, S.; Prabhu, Radhakrishna; Mahadevan Pillai, V. P.

2017-11-01

Barium tungstate films with different Dy3+ doping concentrations, namely 0 wt.%, 1 wt.%, 3 wt.% and 5 wt.%, are deposited on cleaned quartz substrate by radio frequency magnetron sputtering technique and the prepared films are annealed at a temperature of 700°C. The structural, morphological and optical properties of the annealed films are studied using techniques such as x-ray diffraction (XRD), micro-Raman spectroscopy, field emission scanning electron microscopy, atomic force microscopy and photoluminescence spectroscopy. XRD analysis shows that all the films are well-crystallized in nature with a monoclinic barium tungstate phase. The presence of characteristic modes of the tungstate group in the Raman spectra supports the formation of the barium tungstate phase in the films. Scanning electron microscopic images of the films present a uniform dense distribution of well-defined grains with different sizes. All the doped films present a broad emission in the 390-500 nm region and its intensity increases up to 3 wt.% and thereafter decreases due to usual concentration quenching.

High temperature thermometric phosphors for use in a temperature sensor

DOEpatents

Allison, Stephen W.; Cates, Michael R.; Boatner, Lynn A.; Gillies, George T.

1998-01-01

A high temperature phosphor consists essentially of a material having the general formula LuPO.sub.4 :Dy.sub.(x),Eu.sub.(y), wherein: 0.1 wt %.ltoreq.x.ltoreq.20 wt % and 0.1 wt %.ltoreq.y.ltoreq.20 wt %. The high temperature phosphor is in contact with an article whose temperature is to be determined. The article having the phosphor in contact with it is placed in the environment for which the temperature of the article is to be determined. The phosphor is excited by a laser causing the phosphor to fluoresce. The emission from the phosphor is optically focused into a beam-splitting mirror which separates the emission into two separate emissions, the emission caused by the dysprosium dopant and the emission caused by the europium dopent. The separated emissions are optically filtered and the intensities of the emission are detected and measured. The ratio of the intensity of each emission is determined and the temperature of the article is calculated from the ratio of the intensities of the separate emissions.

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.

Frequency dependent dielectric properties of combustion synthesized Dy2Ti2O7 pyrochlore oxide

NASA Astrophysics Data System (ADS)

Jeyasingh, T.; Saji, S. K.; Kavitha, V. T.; Wariar, P. R. S.

2018-05-01

Nanocrystalline pyrochlore material Dysprosium Titanate (Dy2Ti2O7) has been synthesized through a single step optimized combustion route. The phase purity and phase formation of the combustion product has been characterized using X-Ray diffraction analysis (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR) analysis. X-Ray diffraction analysis (XRD) reveal that Dy2Ti2O7 is highly crystalline in nature with cubic structure in the Fd3m space group. The microstructures and average particle size of the prepared nanopowder were examined by High Resolution Transmission Electron Microscopy (HR-TEM). The optical band gap of the Dy2Ti2O7 nanoparticles is determined from the absorption spectrum, was attributed to direct allowed transitions through optical band gap of 3.98 eV. The frequency dependent dielectric measurements have been carried out on the sintered pellet in the frequency range 1 Hz-10 MHz. The measured value of dielectric constant (ℇ') was ˜ 43 and loss tangent (tan δ) was 4×10-3 at 1 MHz, at room temperature.

Rare-earth doped gadolinia based phosphors for potential multicolor and white light emitting deep UV LEDs.

PubMed

Bedekar, Vinila; Dutta, Dimple P; Mohapatra, M; Godbole, S V; Ghildiyal, R; Tyagi, A K

2009-03-25

Gadolinium oxide host and europium/dysprosium/terbium doped gadolinium oxide nanoparticles were synthesized using the sonochemical technique. Gadolinium oxide nanocrystals were also co-doped with total 2 mol% of Eu(3+)/Dy(3+),Eu(3+)/Tb(3+),Dy(3+)/Tb(3+), and also Eu(3+)/Dy(3+)/Tb(3+) ions, by the same method. The nanoparticles obtained were characterized using powder x-ray diffraction (XRD), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) techniques. The size of the particles ranged from 15 to 30 nm. The triple doped samples showed multicolor emission on single wavelength excitation. The photoluminescence results were correlated with the lifetime data to get an insight into the luminescence and energy transfer processes taking place in the system. On excitation at 247 nm, the novel nanocrystalline Gd(2)O(3):RE (RE = Dy, Tb) phosphor resulted in having very impressive CIE chromaticity coordinates of x = 0.315 and y = 0.316, and a correlated color temperature of 6508 K, which is very close to standard daylight.

Magnetic properties of bulk, and rapidly solidified nanostructured (Nd 1-xCe x) 2Fe 14-yCo yB ribbons

DOE PAGES

Pathak, Arjun K.; Khan, M.; Gschneidner, Jr., K. A.; ...

2015-11-06

Magnetic properties of Ce and Co co-doped (Nd 1-xCe x) 2Fe 14-yCo yB compounds have been investigated both in bulk polycrystalline and rapidly solidified nanostructured ribbon forms. For certain Ce concentrations the materials exhibit spin re-orientation transitions below 140 K. The Curie temperatures, saturation magnetizations, and other magnetic properties relevant for applications as permanent magnets are controlled by Ce and Co substitutions for Nd and Fe, respectively. Most importantly, the results show that Ce, Co co-doped compounds are excellent replacements for several Dy-based high performance permanent magnets (dysprosium is one of the critical elements and is, therefore, in short supply).more » As a result, the high temperature (>375 K) magnetic properties for Nd–Ce–Fe–Co–B based alloys show promise not only as a replacement for Dy-doped Nd 2Fe 14B permanent magnets, but the new alloys also require significantly lower amounts of Nd, which too is the critical element that can be replaced by a more abundant Ce.« less

Research of green emitting rare-earth doped materials as potential quantum-cutter

NASA Astrophysics Data System (ADS)

Moine, Bernard; Beauzamy, Lena; Gredin, Patrick; Wallez, Gilles; Labeguerie, Jessica

2008-03-01

Because the energy of vacuum ultraviolet (VUV) photons emitted by xenon plasma discharge is more than twice that of visible photons, quantum cutting appears to be a promising process in rare-earth doped materials in order to obtain efficient phosphors for mercury free lighting devices as well as for plasma display panels. With an aim of application, it is important to take into account the emitting color of the developed new phosphors. Most of the time, this leads to use systems with at least two kinds of rare earth ions: one of them playing the role of energy sensitizer, and the other one being in charge of emitting the light of the suitable color. We focus our attention on green rare-earth doped materials. In order to get very efficient phosphors, it is not only necessary to get the highest possible quantum yield, but also to have a material characterized by a strong absorption in the VUV range. Borate and fluoride matrices doped with Dy 3+/Tb 3+ couples of ions are selected according to the position of the 5d band of dysprosium as green emitters.

Degradation of the electrical characteristics of MOS structures with erbium, gadolinium, and dysprosium oxides under the effect of an electric field

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

Shalimova, M. B., E-mail: shamb@samsu.ru; Sachuk, N. V.

2015-08-15

The degradation of the characteristics of silicon metal-oxide-semiconductor (MOS) structures with oxides of rare-earth elements under the effect of electric fields with intensities of 0.1–4 MV/cm during the course of electroforming is studied. A specific feature of electroforming consists in the possibility of multiple switching of the structures from the insulating state to the low-resistivity one and back. The temporal characteristics of the degradation of MOS structures during the course of electroforming are exponential. The current-voltage characteristics follow the power law in the range of 0.2–3 V; the effect of an electric field brings about a variation in the distributionmore » of the energy density of traps responsible for currents limited by space charge. It is established that multiple cycles of electroforming lead to an increase in the density of surface states at the Si-oxide interface and to a variation in the energy position of the trap levels, which affects the charge state of the traps.« less

Selective Extraction of Rare Earth Elements from Permanent Magnet Scraps with Membrane Solvent Extraction.

PubMed

Kim, Daejin; Powell, Lawrence E; Delmau, Lætitia H; Peterson, Eric S; Herchenroeder, Jim; Bhave, Ramesh R

2015-08-18

The rare earth elements (REEs) such as neodymium, praseodymium, and dysprosium were successfully recovered from commercial NdFeB magnets and industrial scrap magnets via membrane assisted solvent extraction (MSX). A hollow fiber membrane system was evaluated to extract REEs in a single step with the feed and strip solutions circulating continuously through the MSX system. The effects of several experimental variables on REE extraction such as flow rate, concentration of REEs in the feed solution, membrane configuration, and composition of acids were investigated with the MSX system. A multimembrane module configuration with REEs dissolved in aqueous nitric acid solutions showed high selectivity for REE extraction with no coextraction of non-REEs, whereas the use of aqueous hydrochloric acid solution resulted in coextraction of non-REEs due to the formation of chloroanions of non-REEs. The REE oxides were recovered from the strip solution through precipitation, drying, and annealing steps. The resulting REE oxides were characterized with XRD, SEM-EDX, and ICP-OES, demonstrating that the membrane assisted solvent extraction is capable of selectively recovering pure REEs from the industrial scrap magnets.

Manufacturing of Dysprosium-Iron Alloys by Electrolysis in Fluoride-Based Electrolytes: Oxide Solubility Determinations

NASA Astrophysics Data System (ADS)

Martinez, Ana Maria; Støre, Anne; Osen, Karen Sende

2018-04-01

Electrolytic production of light rare earth elements and alloys takes place in a fluoride-based electrolyte using rare earth oxides as raw material. The optimization of this method, mainly in terms of the energy efficiency and environmental impact control, is rather challenging. Anode effects, evolution of fluorine-containing compounds, and side cathode reactions could largely be minimized by a good control of the amount of rare earth oxide species dissolved in the fluoride-based electrolyte and their dissolution rate. The oxide content of the fluoride melts REF3-LiF (RE = Nd, Dy) at different compositions and temperatures were experimentally determined by carbothermal analysis of melt samples. The highest solubility values of oxide species, added as Dy2O3 and Dy2(CO3)3, were obtained to be of ca. 3 wt pct (expressed as Dy2O3) in the case of the equimolar DyF3-LiF melt at 1323 K (1050 °C). The oxide saturation values increased with the amount of REF3 present in the molten bath and the working temperature.