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Sample records for lutetium borides

  1. Two-level systems and negative thermal expansion of lutetium borides

    NASA Astrophysics Data System (ADS)

    Novikov, V. V.; Mitroshenkov, N. V.; Kornev, B. I.; Matovnikov, A. V.

    2017-05-01

    The heat capacity Cv(T) and unit cell volume V(T) temperature dependencies of lutetium borides LuB2 and LuB4 in the region of 2-300 K were analysed in the Debye-Einstein approximation. The characteristic temperatures of the Debye and Einstein components of boride heat capacity and thermal expansion were found. The anomalous contribution to the borides' thermal characteristics was revealed. This contribution was attributed to the influence of two-level systems (TLS), formed in the subsystem of lutetium ions due to asymmetry in the way they are surrounded by the boron atoms in the boride crystal structure. The TLS influence is revealed on heat capacity temperature dependencies by the Schottky-type maxima at Tmax LuB2 =13.8 K, Tmax LuB4 =22.7 K, as well as by the negative contribution to the borides' thermal expansion. The borides' Grüneisen parameters corresponding to the heat capacity and thermal expansion TLS anomalies are negative, and amount to several 10 s of units.

  2. Heat capacity and thermal expansion of icosahedral lutetium boride LuB66

    SciTech Connect

    Novikov, V V; Avdashchenko, D V; Matovnikov, A V; Mitroshenkov, N V; Bud’ko, S L

    2014-01-07

    The experimental values of heat capacity and thermal expansion for lutetium boride LuB66 in the temperature range of 2-300 K were analysed in the Debye-Einstein approximation. It was found that the vibration of the boron sub-lattice can be considered within the Debye model with high characteristic temperatures; low-frequency vibration of weakly connected metal atoms is described by the Einstein model.

  3. Lutetium ultraphosphate.

    PubMed

    Horchani-Naifer, Karima; Férid, Mokhtar

    2008-05-10

    The structure of the title compound, LuP(5)O(14), comprises puckered eight-membered PO(4) rings linked by the lutetium cations in a complex way, forming a three-dimensional framework. Each eight-membered phosphate ring shares a bridging tetra-hedron with each of four adjacent tetra-hedra, to form layers of PO(4) tetra-hedra. These layers are c/2 in thickness and parallel to the ab plane. Each Lu ion is contained in one such layer, forming bonds to six O atoms in that layer and also to one O atom belonging to a tetra-hedron in each of the layers lying above and below it. The LuO(8) polyhedra are isolated from one another, since they share no common atoms. The Lu ions lie on twofold axes (special position 4e) and the shortest Lu⋯Lu distance is 5.703 (1) Å.

  4. Lutetium ultraphosphate

    PubMed Central

    Horchani-Naifer, Karima; Férid, Mokhtar

    2008-01-01

    The structure of the title compound, LuP5O14, comprises puckered eight-membered PO4 rings linked by the lutetium cations in a complex way, forming a three-dimensional framework. Each eight-membered phosphate ring shares a bridging tetra­hedron with each of four adjacent tetra­hedra, to form layers of PO4 tetra­hedra. These layers are c/2 in thickness and parallel to the ab plane. Each Lu ion is contained in one such layer, forming bonds to six O atoms in that layer and also to one O atom belonging to a tetra­hedron in each of the layers lying above and below it. The LuO8 polyhedra are isolated from one another, since they share no common atoms. The Lu ions lie on twofold axes (special position 4e) and the shortest Lu⋯Lu distance is 5.703 (1) Å. PMID:21202435

  5. Gradient boride layers formed by diffusion carburizing and laser boriding

    NASA Astrophysics Data System (ADS)

    Kulka, M.; Makuch, N.; Dziarski, P.; Mikołajczak, D.; Przestacki, D.

    2015-04-01

    Laser boriding, instead of diffusion boriding, was proposed to formation of gradient borocarburized layers. The microstructure and properties of these layers were compared to those-obtained after typical diffusion borocarburizing. First method of treatment consists in diffusion carburizing and laser boriding only. In microstructure three zones are present: laser borided zone, hardened carburized zone and carburized layer without heat treatment. However, the violent decrease in the microhardness was observed below the laser borided zone. Additionally, these layers were characterized by a changeable value of mass wear intensity factor thus by a changeable abrasive wear resistance. Although at the beginning of friction the very low values of mass wear intensity factor Imw were obtained, these values increased during the next stages of friction. It can be caused by the fluctuations in the microhardness of the hardened carburized zone (HAZ). The use of through hardening after carburizing and laser boriding eliminated these fluctuations. Two zones characterized the microstructure of this layer: laser borided zone and hardened carburized zone. Mass wear intensity factor obtained a constant value for this layer and was comparable to that-obtained in case of diffusion borocarburizing and through hardening. Therefore, the diffusion boriding could be replaced by the laser boriding, when the high abrasive wear resistance is required. However, the possibilities of application of laser boriding instead of diffusion process were limited. In case of elements, which needed high fatigue strength, the substitution of diffusion boriding by laser boriding was not advisable. The surface cracks formed during laser re-melting were the reason for relatively quickly first fatigue crack. The preheating of the laser treated surface before laser beam action would prevent the surface cracks and cause the improved fatigue strength. Although the cohesion of laser borided carburized layer was

  6. Method for ultra-fast boriding

    DOEpatents

    Erdemir, Ali; Sista, Vivekanand; Kahvecioglu, Ozgenur; Eryilmaz, Osman Levent

    2017-01-31

    An article of manufacture and method of forming a borided material. An electrochemical cell is used to process a substrate to deposit a plurality of borided layers on the substrate. The plurality of layers are co-deposited such that a refractory metal boride layer is disposed on a substrate and a rare earth metal boride conforming layer is disposed on the refractory metal boride layer.

  7. Fermi surface measurements of lutetium

    NASA Astrophysics Data System (ADS)

    Johanson, W. R.; Crabtree, G. W.; Schmidt, F. A.

    1982-03-01

    We report de Haas-van Alphen (dHvA) measurements of the Fermi surface of lutetium at temperatures down to 0.3 K and in fields up to 150 kG in the (101¯0) and (112¯0) planes. Lutetium, having a filled 4f shell, serves as a nonmagnetic prototype of the structurally similar (hcp), trivalent, heavy rare earths from Gd to Tm. No complete frequency branches were observed, indicating that there are no closed pieces of surface. We observed all but one orbit predicted by relativistic-augmented-plane wave (RAPW) calculations of Keeton and Loucks, and the data support a geometry that is in good qualitative agreement with the existence of nested open electron and hole sheets.

  8. Fermi surface measurements of lutetium

    SciTech Connect

    Johanson, W.R.; Crabtree, G.W.; Schmidt, F.A.

    1982-03-01

    We report de Haas-van Alphen (dHvA) measurements of the Fermi surface of lutetium at temperatures down to 0.3 K and in fields up to 150 kG in the (1010) and (1120) planes. Lutetium, having a filled 4f shell, serves as a nonmagnetic prototype of the structurally similar (hcp), trivalent, heavy rare earths from Gd to Tm. No complete frequency branches were observed, indicating that there are no closed pieces of surface. We observed all but one orbit predicted by relativistic-augmented-plane wave (RAPW) calculations of Keeton and Loucks, and the data support a geometry that is in good qualitative agreement with the existence of nested open electron and hole sheets.

  9. Fermi surface measurements of lutetium

    SciTech Connect

    Johanson, W.R.; Crabtree, G.W.; Schmidt, F.A.

    1982-01-01

    We report de Haas-van Alphen (dHvA) measurements of the Fermi surface of Lutetium at temperatures down to .3K and in fields up to 150 kG in the (1010) and (1120) planes. Lutetium, having a filled 4f shell, serves as a non-magnetic prototype of the structurally similar (hcp), trivalent, heavy rare-earths from Gd to Tm. No complete frequency branches were observed, indicating that there are no closed pieces of surface. We observed all but one orbit predicted by relativistic-augmented-plane wave (RAPW) calculations of Keeton and Loucks, and the data support a geometry that is in good qualitative agreement with the existence of nested open electron and hole sheets.

  10. Selective photoionisation of lutetium isotopes

    SciTech Connect

    D'yachkov, Aleksei B; Kovalevich, S K; Labozin, Valerii P; Mironov, Sergei M; Panchenko, Vladislav Ya; Firsov, Valerii A; Tsvetkov, G O; Shatalova, G G

    2012-10-31

    A three-stage laser photoionisation scheme intended for enriching the {sup 176}Lu isotope from natural lutetium was considered. An investigation was made of the hyperfine structure of the second excited state 5d6s7s {yields} {sup 4}D{sub 3/2} with an energy of 37194 cm{sup -1} and the autoionisation state with an energy of 53375 cm{sup -1} of the {sup 176}Lu and {sup 175}Lu isotopes. The total electron momentum of the autoionisation level and the constant A of hyperfine magnetic interaction were determined. Due to a small value of the isotopic shift between {sup 176}Lu and {sup 175}Lu, appreciable selectivity of their separation may be achieved with individual hyperfine structure components. The first tentative enrichment of the 176Lu isotope was performed to a concentration of 60 % - 70 %. (laser applications and other topics in quantum electronics)

  11. Rediscovering the Crystal Chemistry of Borides.

    PubMed

    Akopov, Georgiy; Yeung, Michael T; Kaner, Richard B

    2017-03-21

    For decades, borides have been primarily studied as crystallographic oddities. With such a wide variety of structures (a quick survey of the Inorganic Crystal Structure Database counts 1253 entries for binary boron compounds!), it is surprising that the applications of borides have been quite limited despite a great deal of fundamental research. If anything, the rich crystal chemistry found in borides could well provide the right tool for almost any application. The interplay between metals and the boron results in even more varied material's properties, many of which can be tuned via chemistry. Thus, the aim of this review is to reintroduce to the scientific community the developments in boride crystal chemistry over the past 60 years. We tie structures to material properties, and furthermore, elaborate on convenient synthetic routes toward preparing borides.

  12. Field free, directly heated lanthanum boride cathode

    DOEpatents

    Leung, Ka-Ngo; Moussa, D.; Wilde, S.B.

    1987-02-02

    A directly heated cylindrical lanthanum boride cathode assembly is disclosed which minimizes generation of magnetic field which would interfere with electron emission from the cathode. The cathode assembly comprises a lanthanum boride cylinder in electrical contact at one end with a central support shaft which functions as one electrode to carry current to the lanthanum boride cylinder and in electrical contact, at its opposite end with a second electrode which is coaxially position around the central support shaft so that magnetic fields generated by heater current flowing in one direction through the central support shaft are cancelled by an opposite magnetic field generated by current flowing through the lanthanum boride cylinder and the coaxial electrode in a direction opposite to the current flow in the central shaft.

  13. Field free, directly heated lanthanum boride cathode

    DOEpatents

    Leung, Ka-Ngo; Moussa, David; Wilde, Stephen B.

    1991-01-01

    A directly heated cylindrical lanthanum boride cathode assembly is disclosed which minimizes generation of magnetic fields which would interfere with electron emission from the cathode. The cathode assembly comprises a lanthanum boride cylinder in electrical contact at one end with a central support shaft which functions as one electrode to carry current to the lanthanum boride cylinder and in electrical contact, at its opposite end with a second electrode which is coaxially position around the central support shaft so that magnetic fields generated by heater current flowing in one direction through the central support shaft are cancelled by an opposite magnetic field generated by current flowing through the lanthanum boride cylinder and the coaxial electrode in a direction opposite to the current flow in the central shaft.

  14. Characterization of AISI 4140 borided steels

    NASA Astrophysics Data System (ADS)

    Campos-Silva, I.; Ortiz-Domínguez, M.; López-Perrusquia, N.; Meneses-Amador, A.; Escobar-Galindo, R.; Martínez-Trinidad, J.

    2010-02-01

    The present study characterizes the surface of AISI 4140 steels exposed to the paste-boriding process. The formation of Fe 2B hard coatings was obtained in the temperature range 1123-1273 K with different exposure times, using a 4 mm thick layer of boron carbide paste over the material surface. First, the growth kinetics of boride layers at the surface of AISI 4140 steels was evaluated. Second, the presence and distribution of alloying elements on the Fe 2B phase was measured using the Glow Discharge Optical Emission Spectrometry (GDOES) technique. Further, thermal residual stresses produced on the borided phase were evaluated by X-ray diffraction (XRD) analysis. The fracture toughness of the iron boride layer of the AISI 4140 borided steels was estimated using a Vickers microindentation induced-fracture testing at a constant distance of 25 μm from the surface. The force criterion of fracture toughness was determined from the extent of brittle cracks, both parallel and perpendicular to the surface, originating at the tips of an indenter impression. The fracture toughness values obtained by the Palmqvist crack model are expressed in the form KC( π/2) > KC > KC(0) for the different applied loads and experimental parameters of the boriding process.

  15. A kinetic model for the borided layers by the paste-boriding process

    NASA Astrophysics Data System (ADS)

    Keddam, M.

    2004-09-01

    This work is dedicated to the study of the growth kinetics of the borided layers obtained by the paste-boriding process. A diffusion model based on Fick's laws and coupled with a thermodynamic description of the Fe-B binary system was suggested to simulate the growth kinetics of the borided layers consisting only of Fe 2B phase and containing 8.83 wt.% B onto the iron substrate within the temperature range of 1223-1323 K. The validation of the diffusion model was achieved by comparing the simulation results with the experimental data taken from the literature and a good agreement was observed. Furthermore, the model was able to predict the boron-depth-concentration profile for Fe 2B phase as well as the thickness of the borided layers depending on the boriding parameters.

  16. Ultra-fast boriding of metal surfaces for improved properties

    SciTech Connect

    Timur, Servet; Kartal, Guldem; Eryilmaz, Osman L.; Erdemir, Ali

    2015-02-10

    A method of ultra-fast boriding of a metal surface. The method includes the step of providing a metal component, providing a molten electrolyte having boron components therein, providing an electrochemical boriding system including an induction furnace, operating the induction furnace to establish a high temperature for the molten electrolyte, and boriding the metal surface to achieve a boride layer on the metal surface.

  17. Kinetics of electrochemical boriding of low carbon steel

    NASA Astrophysics Data System (ADS)

    Kartal, G.; Eryilmaz, O. L.; Krumdick, G.; Erdemir, A.; Timur, S.

    2011-05-01

    In this study, the growth kinetics of the boride layers forming on low carbon steel substrates was investigated during electrochemical boriding which was performed at a constant current density of 200 mA/cm 2 in a borax based electrolyte at temperatures ranging from 1123 K to 1273 K for periods of 5-120 min. After boriding, the presence of both FeB and Fe 2B phases were confirmed by the X-ray diffraction method. Cross-sectional microscopy revealed a very dense and thick morphology for both boride phases. Micro hardness testing of the borided steel samples showed a significant increase in the hardness of the borided surfaces (i.e., up to (1700 ± 200) HV), while the hardness of un-borided steel samples was approximately (200 ± 20) HV. Systematic studies over a wide range of boriding time and temperature confirmed that the rate of the boride layer formation is strongly dependent on boriding duration and has a parabolic character. The activation energy of boride layer growth for electrochemical boriding was determined as (172.75 ± 8.6) kJ/mol.

  18. Magnesium Aluminum Borides as Explosive Materials

    DTIC Science & Technology

    2011-12-20

    Analog to MgB2,” Phys. Rev. B, 73[18] 180501-4 (2006). 29. Handbook of Chemistry and Physics, 63rd Edition ( CRC Press, Boca Raton, 1982). 30. R. Naslain...Engineering Properties of Borides,” Engineered Materials Handbook , Ceramics and Glasses, Vol. 4 (ASM, Metals Park, PA. 1991). 2. G. V. Samsonov and...I. M. Vinitskii, Handbook of Refractory Compounds (Plenum Press, 1980). 3. T. Lundstrom, “Transition Metal Borides,” pp. 351-376 in Boron and

  19. 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 0.15boride compound self-heals, resisting degradation from radiation damage.

  20. The fracture toughness of borides formed on boronized cold work tool steels

    SciTech Connect

    Sen, Ugur; Sen, Saduman

    2003-06-15

    In this study, the fracture toughness of boride layers of two borided cold work tool steels have been investigated. Boriding was carried out in a salt bath consisting of borax, boric acid, ferro-silicon and aluminum. Boriding was performed at 850 and 950 deg. C for 2 to 7 h. The presence of boride phases were determined by X-ray diffraction (XRD) analysis. Hardness and fracture toughness of borides were measured via Vickers indenter. Increasing of boriding time and temperature leads to reduction of fracture toughness of borides. Metallographic examination showed that boride layer formed on cold work tool steels was compact and smooth.

  1. Calibration of the lutetium-hafnium clock.

    PubMed

    Scherer, E; Munker, C; Mezger, K

    2001-07-27

    Well-defined constants of radioactive decay are the cornerstone of geochronology and the use of radiogenic isotopes to constrain the time scales and mechanisms of planetary differentiation. Four new determinations of the lutetium-176 decay constant (lambda176Lu) made by calibration against the uranium-lead decay schemes yield a mean value of 1.865 +/- 0.015 x 10(-11) year(-1), in agreement with the two most recent decay-counting experiments. Lutetium-hafnium ages that are based on the previously used lambda176Lu of 1.93 x 10(-11) to 1.94 x 10(-11) year(-1) are thus approximately 4% too young, and the initial hafnium isotope compositions of some of Earth's oldest minerals and rocks become less radiogenic relative to bulk undifferentiated Earth when calculated using the new decay constant. The existence of strongly unradiogenic hafnium in Early Archean and Hadean zircons implies that enriched crustal reservoirs existed on Earth by 4.3 billion years ago and persisted for 200 million years or more. Hence, current models of early terrestrial differentiation need revision.

  2. Lutetium oxide-based transparent ceramic scintillators

    DOEpatents

    Seeley, Zachary; Cherepy, Nerine; Kuntz, Joshua; Payne, Stephen A.

    2016-01-19

    In one embodiment, a transparent ceramic of sintered nanoparticles includes gadolinium lutetium oxide doped with europium having a chemical composition (Lu.sub.1-xGd.sub.x).sub.2-YEu.sub.YO.sub.3, where X is any value within a range from about 0.05 to about 0.45 and Y is any value within a range from about 0.01 to about 0.2, and where the transparent ceramic exhibits a transparency characterized by a scatter coefficient of less than about 10%/cm. In another embodiment, a transparent ceramic scintillator of sintered nanoparticles, includes a body of sintered nanoparticles including gadolinium lutetium oxide doped with a rare earth activator (RE) having a chemical composition (Lu.sub.1-xGd.sub.x).sub.2-YRE.sub.YO.sub.3, where RE is selected from the group consisting of: Sm, Eu, Tb, and Dy, where the transparent ceramic exhibits a transparency characterized by a scatter coefficient of less than about 10%/cm.

  3. Simulation of the growth kinetics of boride layers formed on Fe during gas boriding in H2-BCl3 atmosphere

    NASA Astrophysics Data System (ADS)

    Kulka, M.; Makuch, N.; Pertek, A.; Małdziński, L.

    2013-03-01

    The modeling of the boriding kinetics is considered as a necessary tool to select the suitable process parameters for obtaining boride layer of an adequate thickness. Therefore, the simulation of the growth kinetics of boride layers has gained much attention for last years. The majority of the published works described the kinetics of the pack-boriding or paste-boriding. In this study, the model of growth kinetics of two-phase boride layer (FeB+Fe2B) on pure Fe was proposed for gas boriding. Displacements of the two interfaces (FeB/Fe2B and Fe2B/substrate) resulted from a difference of the arrival flux of interstitial boron atoms to one phase and the departure flux of the boron atoms from this phase to the second phase. The mass balance equations were formulated. The measurements of thickness of both zones (FeB and Fe2B), for different temperature of boriding, were used for calculations. Based on the experimental data, the parabolic growth constants AFeB and B versus the temperature of boriding were determined. The linear relationships were accepted. As a consequence, the activation energies (QFeB and Q) were calculated. The calculated values were comparable to other data derived from gas boriding. The presented model can predict the thicknesses of the FeB and Fe2B zones (XFeB and Y, respectively) formed on pure Fe during gas boriding. Additionally, the diffusion annealing after boriding was analyzed. This process was carried out in order to obtain a single-phase boride layer (Fe2B). The relationship between the reduction in FeB zone (dXFeB) and the growth in Fe2B phase (dY) was determined. The time tXFeB=0, needed for the total elimination of FeB phase in the boride layer was calculated and compared to the experimental data.

  4. Investigation of the fracture mechanics of boride composites

    NASA Technical Reports Server (NTRS)

    Kaufman, L.; Clougherty, E. V.; Nesor, H.

    1971-01-01

    Fracture energies of WC-6Co, Boride 5 (ZrB2+SiC), Boride 8(ZrB2+SiC+C) and Boride 8-M2(ZrB2+SiC+C) were measured by slow bend and impact tests of notched charpy bars. Cobalt bonded tungsten carbide exhibited impact energies of 0.76 ft-lb or 73.9 in-lb/square inch. Boride 5 and the Boride 8 exhibit impact energies one third and one quarter of that observed for WC-6Co comparing favorably with measurements for SiC and Si3N4. Slow bend-notched bar-fracture energies for WC-6Co were near 2.6 in-lb/square inch or 1/20 the impact energies. Slow bend energies for Boride 8-M2, Boride 8 and Boride 5 were 58%, 42% and 25% of the value observed for WC-6Co. Fractograph showed differences for WC-6Co where slow bend testing resulted in smooth transgranular cleavage while samples broken by impact exhibited intergranular failures. By contrast the boride fractures showed no distinction based on testing method. Fabrication studies were conducted to effect alteration of the boride composites by alloying and introduction of graphite cloth.

  5. Mechanism of boriding from pastes in a glow discharge

    SciTech Connect

    Isakov, S.A.; Al'tshuler, S.A.

    1987-09-01

    The authors investigate the boridation of steel 45 from the standpoint of the glow-discharge dissociation of a borax paste and the plasma arc spraying of the resulting boron into the steel. The effects of process parameters on the impregnation of boron into the steel and its phase behavior in the boridation process are discussed.

  6. Carbide and boride laser modification of steels

    NASA Astrophysics Data System (ADS)

    Major, Boguslaw; Ebner, Reinhold

    1997-10-01

    Microstructure modification by laser remelting or laser alloying was studied on carbon Ck45 and high speed steels. Laser remelting of Ck45 by overlapping laser tracks led to a great refinement of martensitic structure, especially in the heat affected zone of subsequent laser track. High speed steel (HSS) M2 after laser remelting showed, beside the tetragonal martensite, the diffraction lines of cubic carbides of the M6C and M12C types. Laser alloying of M2 HSS using vanadium carbide (VC) additions caused increasing of eutectic in the interdendritic space, which was accompanied with reduction of the M6C and rising of the MC. M2 HSS laser alloyed with molybdenum carbide (Mo2C) showed formation of the M6C for the hipereutectic compositions while at the highest concentrations of molybdenum, primary dendrites of the M2C and stabilized ferrite were stated. High additions of borides: CrB or VB2; developed formation of the primary borides of blocky type containing a high amount of W, Cr or W, V, respectively. Laser alloying of Ck45 by means of: CrB, VB2 and B4C showed: in the case of CrB an eutectic (alpha) '/M3(C,B)/M2B as well as primary precipitates of the M2B phase for hipereutectic compositions; by adding VB2, the M3B2 and M2B phases were identified experimentally for hipereutectic concentrations; for alloying using B4C, the cellular dendritic structure together with primary borides of the (tau) -M23(C,B)6 phase were stated for hipereutectic compositions. The phase diagrams of M2 HSS + (VC or Mo2C) as well as Ck45 + B4C systems were calculated to predict changes of the constitutions due to laser alloying. Comparison of the solidification structures established experimentally with the calculated phase diagrams revealed a good correlation for the carbides, especially.

  7. Static and Dynamical Properties of heavy actinide Monopnictides of Lutetium.

    PubMed

    Mir, Showkat H; Jha, Prakash C; Islam, M S; Banarjee, Amitava; Luo, Wei; Dabhi, Shweta D; Jha, Prafulla K; Ahuja, R

    2016-07-07

    In this work, density functional theory within the framework of generalized gradient approximation has been used to investigate the structural, elastic, mechanical, and phonon properties of lutetium monopnictides in rock-salt crystal structure. The spin orbit coupling and Hubbard-U corrections are included to correctly predict the essential properties of these compounds. The elastic constants, Young's modulus E, Poisson's ratio v, shear modulus G, anisotropy factor A and Pugh's ratio are computed. We found that all lutetium monopnictides are anisotropic and show brittle character. From the wave velocities along [100], [110] and [111] directions, melting temperature of lutetium monopnictides are predicted. Dynamical stability of these monopnictides has been studied by density functional perturbation theory.

  8. Static and Dynamical Properties of heavy actinide Monopnictides of Lutetium

    PubMed Central

    Mir, Showkat H.; Jha, Prakash C.; Islam, M. S.; Banarjee, Amitava; Luo, Wei; Dabhi, Shweta D.; Jha, Prafulla K.; Ahuja, R.

    2016-01-01

    In this work, density functional theory within the framework of generalized gradient approximation has been used to investigate the structural, elastic, mechanical, and phonon properties of lutetium monopnictides in rock-salt crystal structure. The spin orbit coupling and Hubbard-U corrections are included to correctly predict the essential properties of these compounds. The elastic constants, Young’s modulus E, Poisson’s ratio v, shear modulus G, anisotropy factor A and Pugh’s ratio are computed. We found that all lutetium monopnictides are anisotropic and show brittle character. From the wave velocities along [100], [110] and [111] directions, melting temperature of lutetium monopnictides are predicted. Dynamical stability of these monopnictides has been studied by density functional perturbation theory. PMID:27384709

  9. Hydrothermal synthesis of lutetium disilicate nanoparticles

    SciTech Connect

    Tang Xiaoping; Gao Yanfeng; Chen Hongfei; Luo Hongjie

    2012-04-15

    A simple, low-cost hydrothermal method was developed to synthesize irregular-and rod-shaped lutetium disilicate (Lu{sub 2}Si{sub 2}O{sub 7}) powders with sizes ranging from 71 to 340 nm. The synthesis temperature was 260 Degree-Sign C, which is nearly 1300 Degree-Sign C lower than that required for the solid-state reaction. The results indicated that both the hydrothermal temperature and pH values had great influences on the composition, crystalline phase and morphology of the powders. The formation mechanism, basic thermophysical properties, stability and anticorrosion properties of the Lu{sub 2}Si{sub 2}O{sub 7} powders were also investigated. The obtained powders possessed low thermal conductivity, a suitable thermal expansion coefficient (3.92-5.17 Multiplication-Sign 10{sup -6} K{sup -1}) with the silicon-based substrate and excellent thermal and structural stability. During hot corrosion testing, the surfaces of the samples appeared to react with the water and molten salt vapors, but no serious failure occurred. - Graphical abstract: An image for the as-prepared Lu{sub 2}Si{sub 2}O{sub 7} powders (left) and XRD pattern (right) (inset shows the SEM graph of powders). Highlights: Black-Right-Pointing-Pointer We synthesized Lu{sub 2}Si{sub 2}O{sub 7} powders via a hydrothermal process at 260 Degree-Sign C. Black-Right-Pointing-Pointer Crystalline phase and morphology of the powders changed with experimental parameter. Black-Right-Pointing-Pointer Hot corrosion was determined in an airflow environment containing alkaline vapor.

  10. Microstructure and properties of laser-borided 41Cr4 steel

    NASA Astrophysics Data System (ADS)

    Kulka, M.; Makuch, N.; Pertek, A.

    2013-02-01

    Laser-boriding, instead of diffusion-boriding, was applied to formation of boride layers on 41Cr4 steel. The microstructure and properties of these layers were compared to those obtained after typical diffusion-boriding. Three zones characterized the microstructure of laser-borided layer: laser-borided zone, hardened medium-carbon zone (heat affected zone) and medium-carbon substrate without heat treatment. The through-hardened laser-borided steel was also analyzed. In this case two zones characterized the microstructure: laser-borided zone and hardened medium-carbon substrate. The microstructure of laser-borided zone consisted of eutectic mixture of borides and martensite. This phase composition (especially martensite presence) was the reason for microhardness decrease at the surface in comparison with diffusion-borided steel. However, the use of laser-boriding causes the decrease in microhardness gradient between the surface and the substrate in comparison with typical diffusion-boriding process. The value of mass wear intensity factor of the hardened laser-borided layer was comparable to that obtained in case of diffusion-boriding and through-hardening. The use of laser-borided layers instead of typical diffusion-borided layers may be advantageous under conditions of high abrasive wear of mating parts. For the experimental condition used, the laser-boriding process presented worst results concerning the fatigue strength. The cracks formed on the surface during laser re-melting were the reason for relatively quick first fatigue crack. In case of elements, which require high fatigue strength, the use of modified laser processing parameters would be necessary. The better results should be obtained by increasing of tracks overlapping. Although the cohesion of laser-borided layer was sufficient, the diffusion-borided layer showed a better cohesion.

  11. Boriding of high carbon high chromium cold work tool steel

    NASA Astrophysics Data System (ADS)

    Muhammad, W.

    2014-06-01

    High-carbon high-chromium cold work tool steels are widely used for blanking and cold forming of punches and dies. It is always advantageous to obtain an increased wear resistant surface to improve life and performance of these steels. In this connection boriding of a high-carbon high-chromium cold work die steel, D3, was conducted in a mixture of 30% B4C, 70% borax at 950 °C for two, four and six hours. Case depth of the borided layer obtained was between 40 to 80 μm. After boriding, the surface hardness achieved was between 1430 to 1544 HV depending upon the process time. X-ray diffraction studies confirmed the formation of a duplex compound layer consisting of FeB and Fe2B. It is generally considered that FeB is undesirable because of its inherent brittleness. Post boriding treatment (homogenization) transformed the compound layer into single-phase layer of Fe2B, while surface hardness decreased to 1345-1430 HV. Pin-on-disc wer test showed that wear resistance of the borided samples was superior as compared to non-borided material and increased with boriding time.

  12. Boron diffusion in silicon from metal boride sources

    SciTech Connect

    Ryan, J.G.

    1988-01-01

    Thin films of titanium and lanthanum borides were investigated as potential boron diffusion sources. TiB{sub x} and LaB{sub 6} films exhibited room-temperature film stresses and resistivity values similar to refractory-metal silicides, and acted as boron diffusion sources, producing diffusions with high surface concentrations. The source of boron from TiB{sub x} films appears to be the excess boron present in the metal boride or at the metal boride-silicon substrate interface. Boron surface concentration increases with increasing mole fraction of boron in the metal boride source. Boron surface concentration peaks at 1000{degree}C for furnace-annealed TiB{sub 2.2}, but rises until a plateau is reached at 1050{degree}C for rapid-annealed samples of the same composition. The concentration of electrically active boron was consistently lower than the chemical concentration in these studies. The stability of the boride films on silicon substrates was found to be dependent on boride source composition. LaB{sub 6} and TiB films reacted with the silicon substrate. Although the TiB{sub 2.1}, TiB{sub 2.2}, and TiB{sub 2.9} films did not decompose or allow Si to diffuse into them, a silicon boride surface layer was formed in the silicon substrate caused by boron out-diffusing from these sources during furnace annealing.

  13. Synthesis and properties of nanoscale titanium boride

    NASA Astrophysics Data System (ADS)

    Efimova, K. A.; Galevskiy, G. V.; Rudneva, V. V.

    2015-09-01

    This work reports the scientific and technological grounds for plasma synthesis of titanium diboride, including thermodynamic and kinetic conditions of boride formation when titanium and titanium dioxide are interacting with products resulting from boron gasification in the nitrogen - hydrogen plasma flow, and two variations of its behavior using the powder mixtures: titanium - boron and titanium dioxide - boron. To study these technology variations, the mathematical models were derived, describing the relation between element contents in the synthesized products of titanium and free boron and basic parameters. The probable mechanism proposed for forming titanium diboride according to a "vapour - melt - crystal" pattern was examined, covering condensation of titanium vapour in the form of aerosol, boriding of nanoscale melt droplets by boron hydrides and crystallization of titanium - boron melt. The comprehensive physical - chemical certification of titanium diboride was carried out, including the study of its crystal structure, phase and chemical composition, dispersion, morphology and particle oxidation. Technological application prospects for use of titanium diboride nanoscale powder as constituent element in the wettable coating for carbon cathodes having excellent physical and mechanical performance and protective properties.

  14. 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.

  15. 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.

  16. Discovery of gallium, germanium, lutetium, and hafnium isotopes

    SciTech Connect

    Gross, J.L.; Thoennessen, M.

    2012-09-15

    Currently, twenty-eight gallium, thirty-one germanium, thirty-five lutetium, and thirty-six hafnium isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

  17. Pack-boriding of Fe-Mn binary alloys: Characterization and kinetics of the boride layers

    SciTech Connect

    Bektes, M.; Calik, A.; Ucar, N.; Keddam, M.

    2010-02-15

    In this work, the boronizing of Fe-Mn binary alloys at 0.42, 0.76 and 0.94 wt.% Mn was carried out in a solid medium using the powder pack method. In this method, commercial Ekabor-II boron source and activator (ferro-silicon) were thoroughly mixed to form the boriding medium. The samples were boronized in an electrical resistance furnace for exposure times of 2, 4, 6 and 8 h at 1173 K under atmospheric pressure and a series of boronized samples in the temperature range 1073-1373 K for 3 h. After the furnace process, boronized samples were removed from the furnace and cooled in air. Afterwards, the boride layers generated by the pack-boronizing process were characterized by optical microscopy, scanning electron microscopy, XRD analysis, Vickers microhardness and tensile testing. The generated boride layers, showing a saw-tooth morphology, had a surface microhardness in the range 1400-1270 HV0.1. It was shown that the values of yield stresses and ultimate tensile stresses were increased as the Mn content increases in the boronized Fe-Mn binary alloys. In contrast, the values of elongations determined from the stress-strain curves were decreased. Furthermore, it was found that the calculated mean value of the activation energy of boron diffusion was close to 119 J/mol.

  18. 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.

  19. Microstructure, Growth Kinetics and Some Mechanical Properties of Boride Layers Produced on Pure Titanium by Molten-Salt Boriding

    NASA Astrophysics Data System (ADS)

    Ma, L. S.; Duan, Y. H.; Li, P.

    2017-08-01

    To modify the surface properties of pure titanium, boride layers had been fabricated by the boron molten-salt diffusion on pure titanium surfaces in the temperature range of 900-1100 °C for 5- to 30-h treatments. The results demonstrated that the boride layers were mainly composed of TiB whiskers and TiB2 layers without the rutile titanium oxide TiO2. Two diffusion models were introduced to model the growth kinetics of boride layers. The parabolic growth constants and the boron diffusion coefficients were obtained. The boron activation energies for TiB2 and TiB were 225.617 and 165.266 kJ mol-1, respectively. The surface microhardness of the borided titanium decreased with the increase in distance from the surface. The results of wear tests indicated that the wear properties had been improved significantly compared to the pure titanium under dry sliding conditions.

  20. Microstructure and properties of laser-borided Inconel 600-alloy

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

    Nickel-based superalloys are used extensively for a variety of industrial applications involving high temperatures and aggressive environments. However, under conditions of appreciable mechanical wear (adhesive or abrasive), these materials have to be distinguished by suitable wear protection. The diffusion boronizing is the thermo-chemical treatment, which improves the tribological properties of nickel and its alloys. Nevertheless, the long duration of this process is necessary in order to obtain the layers of the thickness up to about 100 μm. Instead of the diffusion process, in this study the laser boriding is used for producing boride layer on Inconel 600-alloy. During the laser alloying, the external cylindrical surface of base material is coated by paste, including amorphous boron. Then the surface is re-melted by a laser beam. The high overlapping of multiple laser tracks (86%) causes the formation of uniform laser-alloyed layer in respect of the thickness. Laser re-melted zone, heat-affected zone and the substrate characterize the microstructure. In the re-melted zone, the three areas are observed: compact borides zone consisting of nickel, chromium and iron borides (close to the surface), zone of increased percentage of Ni-Cr-Fe-matrix (appearing in the greater distance from the surface) and zone of dominant Ni-Cr-Fe-matrix percentage (at the end of the layer). The hardness obtained is comparable to that-obtained in case of diffusion boriding. Simultaneously, the laser-borided layers are significantly thicker (about 346 or 467 μm depending on the laser power used). The significant increase in their abrasive wear resistance is observed. The wear intensity factors, as well as the relative mass loss of the laser-borided samples, are ten times smaller in comparison with untreated Inconel 600-alloy.

  1. Optical Response of Shocked Cerium-Doped Lutetium Oxyorthosilicate

    SciTech Connect

    G. D. Stevens

    2003-03-01

    Shock experiments were performed in order to characterize the triboluminescent signature of cerium-doped lutetium oxyorthosilicate (LSO:Ce). This material shows prompt, nano-second timescale light emission when driven by explosive detonation. When properly applied to a surface, it may be used as a shock arrival sensor, and also for imaging the propagation of a shock front. Triboluminescent rise times, spectral content, and spatial resolution measurements are presented.

  2. Mechanochemically Driven Syntheses of Boride Nanomaterials

    NASA Astrophysics Data System (ADS)

    Blair, Richard G.

    Solid state metathesis reactions have proven to be a viable route to the production of unfunctionalized nanomaterials. However, current implementations of this approach are limited to self-propagating reactions. We have been investigating mechanically driven metathesis reactions. The use of high-energy ball mills allows control of crystallite sizes without the use of a capping group. Reinforcement materials with crystallite sizes on the order of 5-30 nm can be produced in such a manner. Borides are of particular interest due to their strength, high melting point, and electrical conductivity. The ultimate goal of this work is to prepare oxide and capping group-free nanoparticles suitable for incorporation in thermoelectric, polymer, and ceramic composites. Ultimately this work will facilitate the production of improved thermoelectric materials that will provide robust, deployable, power generation modules to supplement or replace fuel cell, Stirling, and battery-derived power sources. It will also result in scalable, bulk syntheses of tough, refractory, conductive nanomaterials for polymer composites with improved electrical properties, ceramic composites with enhanced fracture toughness, and composites with enhanced neutron reflectance and/or absorbance.

  3. Novel magnesium borides and their superconductivity.

    PubMed

    Davari Esfahani, M Mahdi; Zhu, Qiang; Dong, Huafeng; Oganov, Artem R; Wang, Shengnan; Rakitin, Maksim S; Zhou, Xiang-Feng

    2017-06-07

    With the motivation of searching for new superconductors in the Mg-B system, we performed ab initio evolutionary searches for all the stable compounds in this binary system in the pressure range of 0-200 GPa. We found previously unknown, yet thermodynamically stable, compositions MgB3 and Mg3B10. Experimentally known MgB2 is stable in the entire pressure range 0-200 GPa, while MgB7 and MgB12 are stable at pressures below 90 GPa and 35 GPa, respectively. We predict a reentrant behavior for MgB4, which becomes unstable against decomposition into MgB2 and MgB7 at 4 GPa and then becomes stable above 61 GPa. We find ubiquity of phases with boron sandwich structures analogous to the AlB2-type structure. However, with the exception of MgB2, all other magnesium borides have low electron-phonon coupling constants λ of 0.32-0.39 and are predicted to have Tc below 3 K.

  4. Laser borided composite layer produced on austenitic 316L steel

    NASA Astrophysics Data System (ADS)

    Mikołajczak, Daria; Kulka, Michał; Makuch, Natalia

    2016-12-01

    Abstract Austenitic 316L steel is well-known for its good resistance to corrosion and oxidation. Therefore, this material is often used wherever corrosive media or high temperatures are to be expected. The main drawback of this material is very low hardness and low resistance to mechanical wear. In this study, the laser boriding was used in order to improve the wear behavior of this material. As a consequence, a composite surface layer was produced. The microstructure of laser-borided steel was characterized by only two zones: re-melted zone and base material. In the re-melted zone, a composite microstructure, consisting of hard ceramic phases (borides) and a soft austenitic matrix, was observed. A significant increase in hardness and wear resistance of such a layer was obtained.

  5. Molecular Modeling of High-Temperature Oxidation of Refractory Borides

    DTIC Science & Technology

    2008-02-01

    04-Feb 08 Final Technical 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER MOLECULAR MODELING OF HIGH-TEMPERATURE OXIDATION OF REFRACTORY BORIDES 5b. GRANT...Prescribed by ANSI Std. Z39.18 MOLECULAR MODELING OF HIGH-TEMPERATURE OXIDATION OF REFRACTORY BORIDES FA9550-05-1-0026 Final Report (11/15/2004-02/14...deficient centers, instead of molecular 02 as in the Deal-Grove model . These network defects will lead to sub-linear dependence of the oxidation rate with

  6. Evolving Important Role of Lutetium-177 for Therapeutic Nuclear Medicine.

    PubMed

    Pillai, Ambikalmajan M R; Knapp, Furn F Russ

    2015-01-01

    Lutetium-177 ((177)Lu) is a late entrant into the nuclear medicine therapy arena but is expected to become one of the most widely used therapeutic radionuclides. This paper analyses the reason for the increasing preference of (177)Lu as a therapeutic radionuclide. While the radionuclidic properties favor its use for several therapeutic applications, the potential for large scale production of (177)Lu is also an important aspect for its acceptability as a therapeutic radionuclide. This introductory discussion also summarizes some developing clinical uses and suggested future directions for applications of (177)Lu.

  7. Development and application of high strength ternary boride base cermets

    SciTech Connect

    Takagi, Ken-ichi . E-mail: u4381@toyokohan.co.jp

    2006-09-15

    Reaction boronizing sintering is a novel strategy to form a ternary boride coexisting with a metal matrix in a cermet during liquid phase sintering. This new sintering technique has successfully developed world first ternary boride base cermets with excellent mechanical properties such as Mo{sub 2}FeB{sub 2}, Mo{sub 2}NiB{sub 2} and WCoB base ones. In these cermets Mo{sub 2}FeB{sub 2} and Mo{sub 2}NiB{sub 2} base ones consist of a tetragonal M {sub 3}B{sub 2} (M: metal)-type complex boride as a hard phase and a transition metal base matrix. The cermets have already been applied to wear resistant applications such as injection molding machine parts, can making tools, and hot copper extruding dies, etc. This paper focuses on the characteristics, effects of the additional elements on the mechanical properties and structure, and practical applications of the ternary boride base cermets. - Graphical abstract: TRS and hardness of Ni-5B-51Mo-17.5Cr and Ni-5B-51Mo-12.5Cr-5V-xMn mass% cermets as functions of Mn content (Fig. 17)

  8. 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.

  9. Electrochemical Corrosion Behavior of Borided CoCrMo Alloy Immersed in Hanks' Solution

    NASA Astrophysics Data System (ADS)

    Rosas-Becerra, G.; Mejía-Caballero, I.; Martínez-Trinidad, J.; Palomar-Pardavé, M.; Romero-Romo, M.; Pérez-Pasten-Borja, R.; Campos-Silva, I.

    2017-02-01

    New results about the corrosion resistance of borided CoCrMo alloy exposed to the Hanks' solution during different days were estimated by means of the electrochemical impedance spectroscopy technique. The CoB-Co2B coating was developed on the surface of the borided alloy using the powder-pack boriding process at 1223 K during 6 h of exposure. The corrosion resistance of the borided cobalt alloy was evaluated by the fitting of suitable equivalent electrical circuits using Nyquist and Bode plots to obtain the electrochemical parameters; the results were compared with the CoCrMo (non-borided) alloy. The samples (borided and non-borided) were characterized by the scanning electron microscopy and by the energy-dispersive x-ray spectrometry techniques to determine the elemental chemical composition developed on the surface of the materials. In addition, the reaction products formed on the surface of the borided CoCrMo alloy exposed to the Hanks' solution after the tenth day of immersion were analyzed by the x-ray photoelectron spectroscopy (XPS) technique. The results showed that the corrosion resistance of the borided cobalt alloy was affected (or reduced) by the presence of B2S3 and CrPO4 clusters formed on the material's surface. Finally, the electrochemical reactions developed during the immersion of the borided cobalt alloy on the tenth day of exposure were proposed according to the XPS results.

  10. Enhancement of lutetium texaphyrin phototherapy with Mitomycin C

    NASA Astrophysics Data System (ADS)

    Thiemann, Patricia A.; Woodburn, Kathryn W.

    1998-05-01

    Lutetium texaphyrin (Lu-Tex) photodynamic therapy (PDT) relies on the presence of the water-soluble Lu-Tex, oxygen, and light (activation around 730 nm). Cytotoxic oxygen species are produced that cause irreversible damage to biological substrates. Damage may be inflicted via direct cell kill mechanisms or through vasculature effects that cause hypoxia. The addition of hypoxia enhanced drugs, such as Mitomycin C (MMC), can potentially increase the anti-tumor response. RIF-1 bearing C3H mice received 10 micrometers ol Lu-Tex/kg and were illuminated with 100 J/cm2 3 hours postinjection. Mice received MMC (2.5 or 5 mg/kg, before and after light) in conjunction with PDT and were compared to subsets of drug alone controls. A significant improvement in PDT response was observed when MMC was added to the dosing regimen; the effect was more pronounced at the highest MMC dose of 5 mg/kg: MMC prior to PDT gave a median tumor regrowth time (10X original volume) of 28 days compared to MMC and PDT alone, 16.3 and 14.9 days, respectively. The anti-tumor activity of lutetium texaphyrin induced PDT was improved by the addition of the bioreductive alkylating agent mitomycin C.

  11. Electrochromic cells with lutetium diphthalocyanine and semisolid polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Pizzarello, F. A.; Nicholson, M. M.

    1987-11-01

    Cyclic voltammograms were obtained for lutetium diphthalocyanine films in contact with plasticized poly(ethylene oxide) (PEO) electrolytes or solvent-swollen 2-acrylamido-2-methylpropane- sulfonic acid (AMPS) polymer electrolytes. Cells containing PEO-salt combinations plasticized with propylene glycol (PG) or acetonitrile resulted in slow, nonuniform color changes due to high interfacial resistance. The AMPS cell fabrication was simplified by starting with a commercial AMPS polymer product in the form of a transparent sheet containing water and other additives. This material, when further swollen in a PG-HC1 solution, produced the full range of uniform colors, accompanied by well defined voltammograms. It maintained good contact with the dye from -5 to 40 C.

  12. Super-hard coating creation by laser boriding technique

    NASA Astrophysics Data System (ADS)

    Monisha, K.; Kumar, S. Arun; Gunaseelan, M.; Senthilselvan, J.

    2017-05-01

    Laser surface boriding was carried out using boropak and TiB+amorphous boron coated Cp-Ti alloy with high power diode laser (HPDL). The effect of boron agents and laser processing parameters on the microstructure, crystallographic phase formations and hardness are investigated by optical microscopy, scanning electron microscopy, XRD and hardness testing. Super-hard coating with hardness in the range of 1000 to 3000 HV0.2 was created by laser alloying the boropak and TiB+amorphous boron coated Cp-Ti. It is due to the formation of TiB2, TiB and Ti3B4 composite layers. Laser boriding has resulted in 2500 µm thick coating.

  13. An unusual variation of stability and hardness in molybdenum borides

    NASA Astrophysics Data System (ADS)

    Liang, Yongcheng; Yuan, Xun; Fu, Zhao; Li, Yuan; Zhong, Zheng

    2012-10-01

    Molybdenum borides are currently raising great expectations for superhard materials, but their crystal structures and mechanical behaviors are still under discussion. Here, we report an unexpected reduction of stability and hardness from porous hP16-MoB3 and hR18-MoB2 to dense hP20-MoB4 and hR21-Mo2B5, respectively. Furthermore, we demonstrate that this anomalous variation has its electronic origin. These findings not only manifest that the long-recognized hP20-MoB4 (hP3-MoB2) and hR21-Mo2B5 should be hP16-MoB3 and hR18-MoB2, respectively, but also challenge the general design principle for ultrahard materials only pursuing the dense transition-metal borides with high boron content.

  14. Prediction of new crystal structure phases in metal borides

    NASA Astrophysics Data System (ADS)

    Kolmogorov, Aleksey

    2006-03-01

    Identification of novel crystal structures is an important step for predicting new stable compounds in alloys, since most theoretical search algorithms are restricted to a given prototype library or a lattice type. Performing ab initio data mining [1] of intermetallic compounds we have discovered that even in such a well-studied class of systems as metal borides there are previously unknown phases comparable in energy to the existing ones [2]. We demonstrate that even though the new structures are relatively simple, their identification is not straightforward. We systematically investigate the stability and electronic properties of the new metal boride phases. Our calculations show that some phases exhibit electronic features similar to those in the famous MgB2 and could be good superconductors. The new phases are likely to have random stacking faults, so they might not be detected with standard x-ray methods. Our results could thus be used as an important guide in the search for new superconducting metal borides. [1] S. Curtarolo et al., Phys. Rev. Lett. 91, 135503 (2003). [2] A.N. Kolmogorov et al., submitted (2005).

  15. An Evaluation of a Borided Layer Formed on Ti-6Al-4V Alloy by Means of SMAT and Low-Temperature Boriding

    PubMed Central

    Yao, Quantong; Sun, Jian; Fu, Yuzhu; Tong, Weiping; Zhang, Hui

    2016-01-01

    In this paper, a nanocrystalline surface layer without impurities was fabricated on Ti-6Al-4V alloy by means of surface mechanical attrition treatment (SMAT). The grain size in the nanocrystalline layer is about 10 nm and grain morphology displays a random crystallographic orientation distribution. Subsequently, the low-temperature boriding behaviors (at 600 °C) of the SMAT sample, including the phase composition, microstructure, micro-hardness, and brittleness, were investigated in comparison with those of coarse-grained sample borided at 1100 °C. The results showed that the boriding kinetics could be significantly enhanced by SMAT, resulting in the formation of a nano-structured boride layers on Ti-6Al-4V alloy at lower temperature. Compared to the coarse-grained boriding sample, the SMAT boriding sample exhibits a similar hardness value, but improved surface toughness. The satisfactory surface toughness may be attributed to the boriding treatment that was carried out at lower temperature. PMID:28774115

  16. Lutetium-methanediide-alkyl complexes: synthesis and chemistry.

    PubMed

    Li, Shihui; Wang, Meiyan; Liu, Bo; Li, Lei; Cheng, Jianhua; Wu, Chunji; Liu, Dongtao; Liu, Jingyao; Cui, Dongmei

    2014-11-17

    The first four-coordinate methanediide/alkyl lutetium complex (BODDI)Lu2 (CH2 SiMe3 )2 (μ2 -CHSiMe3 )(THF)2 (BODDI=ArNC(Me)CHCOCHC(Me)NAr, Ar=2,6-iPr2 C6 H3 ) (1) was synthesized by a thermolysis methodology through α-H abstraction from a Lu-CH2 SiMe3 group. Complex 1 reacted with equimolar 2,6-iPrC6 H3 NH2 and Ph2 C+O to give the corresponding lutetium bridging imido and oxo complexes (BODDI)Lu2 (CH2 SiMe3 )2 (μ2 -N-2,6-iPr2 C6 H3 )(THF)2 (2) and (BODDI)Lu2 (CH2 SiMe3 )2 (μ2 -O)(THF)2 (3). Treatment of 3 with Ph2 C=O (4 equiv) caused a rare insertion of Lu-μ2 -O bond into theC=O group to afford a diphenylmethyl diolate complex 4. Reaction of 1 with PhN=C=O (2 equiv) led to the migration of SiMe3 to the amido nitrogen atom to give complex (BODDI)Lu2 (CH2 SiMe3 )2 -μ-{PhNC(O)CHC(O)NPh(SiMe3 )-κ(3) N,O,O}(THF) (5). Reaction of 1 withtBuN=C formed an unprecedented product (BODDI)Lu2 (CH2 SiMe3 ){μ2 -[η(2) :η(2) -tBuN=C(=CH2 )SiMe2 CHC=NtBu-κ(1) N]}(tBuN=C)2 (6) through a cascade reaction of N=C bond insertion, sequential cyclometalative γ-(sp(3) )-H activation, C=C bond formation, and rearrangement of the newly formed carbene intermediate. The possible mechanistic pathways between 1, PhN=C=O, and tBuN=C were elucidated by DFT calculations. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. 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.

  18. Octaoctyl-substituted lutetium bisphthalocyanine for NADH biosensing.

    PubMed

    Pal, C; Sharma, A K; Cammidge, A N; Cook, M J; Ray, A K

    2013-12-05

    Cyclic voltammetric and Raman and UV-vis spectroscopic measurements were performed on thin films of nonperipherally substituted bis[1,4,8,11,15,18,22,25-octakis(octyl)phthalocyaninato] lutetium(III) (R16LuPc2). Voltammograms exhibit one-electron quasi-reversible redox processes in 1.5 M LiClO4 aqueous solutions. The red-shift of the Q-band of R16LuPc2 in the UV-visible absorption spectra upon oxidation is attributed to the shortening of the inter-ring distance between the two phthalocyanine moieties. This observation is also consistent with the shift in the redox-sensitive vibrational modes in the Raman spectra due to the localization of the positive charge on phthalocyanine moieties. Neutralization of the oxidized R16LuPc2(+) film by dihydronicotinamide adenine dinucleotide (NADH) using different concentrations varying from 0.05 to 1 mM has been studied by UV-vis absorption and Raman spectroscopies. The reduction processes for a three month old film were found to be slower than those for freshly prepared films and showed a dependence upon NADH concentration. The data provide a basis for application of R16LuPc2 as a sensor for NADH.

  19. Theranostic Applications of Lutetium-177 in Radionuclide Therapy.

    PubMed

    Das, Tapas; Banerjee, Sharmila

    2016-01-01

    Lutetium-177 has been widely discussed as a radioisotope of choice for targeted radionuclide therapy. The simultaneous emission of imageable gamma photons [208 keV (11%) and 113 keV (6.4%)] along with particulate β(-) emission [β(max) = 497 keV] makes it a theranostically desirable radioisotope. In the present article, the possibility of using two 177Lu-based agents viz. 177Lu-EDTMP and 177Lu-DOTATATE for theranostic applications in metastatic bone pain palliation (MBPP) and peptide receptor radionuclide therapy (PRRT), have been explored. In the case of 177Lu-EDTMP, the whole-body images obtained are compared with those recorded using 99mTc-MDP in the same patient. On the other hand, pre-therapy images acquired with 177Lu-DOTA-TATE are compared with similar images obtained with standard agents, such as 99mTc-HYNIC-TOC (SPECT) and 68Ga-DOTA-TOC (PET) in the same patient. The advantage of the long physical half-life (T1/2) of 177Lu has been utilized in mapping the pharmacokinetics of two additional agents, 177Lu-labeled hydroxyapatite (HA) in radiation synovectomy of knee joints and 177Lu-HA for therapy of hepatocellular carcinoma. Results of these multiple studies conclusively document the potential of 177Lu as a theranostic radioisotope.

  20. Synthesis and densification of lutetium pyrosilicate from lutetia and silica

    SciTech Connect

    Tripathi, Himansu S.; Sarin, Vinod K. . E-mail: sarin@bu.edu

    2007-02-15

    Cerium-doped lutetium pyrosilicate (Lu{sub 2}Si{sub 2}O{sub 7}:Ce) powder was synthesized by solid state reaction of Lu{sub 2}O{sub 3} and SiO{sub 2}. Stoichiometric mixtures of the starting materials were heat treated at various different temperatures and their phase contents were measured by XRD technique. It was found that the first step in the formation of Lu{sub 2}Si{sub 2}O{sub 7} (LPS) is the appearance of Lu{sub 2}SiO{sub 5} (LSO). This takes place at 1100 deg. C, fully 300 deg. C below the first appearance of LPS. Between 1400 and 1500 deg. C both LSO and LPS coexist in the calcined batch, but by 1550 deg. C all LSO is completely converted to LPS. LPS formation temperature does not have appreciable effect on the density of the hot pressed samples. Hot pressed samples obtained from powder synthesized at 1650 deg. C are nearly transparent, although the particle size of the starting powder is higher than that of the powder formed at lower temperatures.

  1. Characterisation of titanium-titanium boride composites processed by powder metallurgy techniques

    SciTech Connect

    Selva Kumar, M.; Chandrasekar, P.; Chandramohan, P.; Mohanraj, M.

    2012-11-15

    In this work, a detailed characterisation of titanium-titanium boride composites processed by three powder metallurgy techniques, namely, hot isostatic pressing, spark plasma sintering and vacuum sintering, was conducted. Two composites with different volume percents of titanium boride reinforcement were used for the investigation. One was titanium with 20% titanium boride, and the other was titanium with 40% titanium boride (by volume). Characterisation was performed using X-ray diffraction, electron probe micro analysis - energy dispersive spectroscopy and wavelength dispersive spectroscopy, image analysis and scanning electron microscopy. The characterisation results confirm the completion of the titanium boride reaction. The results reveal the presence of titanium boride reinforcement in different morphologies such as needle-shaped whiskers, short agglomerated whiskers and fine plates. The paper also discusses how mechanical properties such as microhardness, elastic modulus and Poisson's ratio are influenced by the processing techniques as well as the volume fraction of the titanium boride reinforcement. - Highlights: Black-Right-Pointing-Pointer Ti-TiB composites were processed by HIP, SPS and vacuum sintering. Black-Right-Pointing-Pointer The completion of Ti-TiB{sub 2} reaction was confirmed by XRD, SEM and EPMA studies. Black-Right-Pointing-Pointer Hardness and elastic properties of Ti-TiB composites were discussed. Black-Right-Pointing-Pointer Processing techniques were compared with respect to their microstructure.

  2. Microstructural characterization and some mechanical properties of gas-borided Inconel 600-alloy

    NASA Astrophysics Data System (ADS)

    Makuch, N.; Kulka, M.

    2014-09-01

    The excellent resistance of Ni-based alloys to corrosion and oxidation is well-known. Boriding can be applied to these alloys in order to obtain suitable wear protection. In this paper, two-stage gas boronizing in N2-H2-BCl3 atmosphere is proposed for the producing the boride layer on Inconel®600-alloy. This process consists in two stages alternately repeated: saturation by boron and diffusion annealing. Such a gas boriding is applied in order to accelerate the saturation by boron and its diffusion. It turns out to be more effective because of eliminating the excess of boron, diffusing into the substrate, during the second stage. Microstructure and some mechanical properties of the produced layer are presented. Microstructural characterization is studied with using an optical microscope, scanning electron microscope, energy-dispersive x-ray microanalysis and x-ray diffraction. The diffusion zone consists of the mixture of nickel and chromium borides, occurring in the compact boride zone and in the area located beneath, at grain boundaries. The improved hardness and wear resistance characterize the layer. The formed boride layer is significantly thicker than those-obtained by the pack-boronizing or paste process at comparable temperature and time. Simultaneously, the measured depth of layer is slightly smaller than that-reported for electrolytic boriding.

  3. Reactive Boride Brazing on Low-Alloy Automotive Grade Steel

    NASA Astrophysics Data System (ADS)

    Palanisamy, B.; Upadhyaya, A.

    2011-11-01

    Brazing is a widely used process to improve the performance of steels used in automotive applications. The substrate material is often exposed to harsh conditions in these applications and may affect the service life of the component. Reactive boride brazing aims to improve the mechanical properties of the substrate material by forming a ceramic-metal composite coating in a single-step process in situ. In this study, sintered Ancor 4300 low-alloy steel is used as the substrate with chromium-rich braze and chromium-lean braze materials. The mechanical properties of the brazed samples were studied in detail using microindentation hardness measurements and the transverse rupture test. The results indicate that the brazed superlayer has a 10 times higher hardness. There was a significant improvement in the transverse rupture strength of the steel brazed with the chromium-rich boride as compared to the pure substrate material. In an effort to reduce processing time, green compacts of the substrate were also directly brazed and yielded favorable results.

  4. Metal borohydride formation from aluminium boride and metal hydrides.

    PubMed

    Møller, Kasper T; Fogh, Alexander S; Paskevicius, Mark; Skibsted, Jørgen; Jensen, Torben R

    2016-10-05

    Metal borides are often decomposition products from metal borohydrides and thus play a role in the reverse reaction where hydrogen is absorbed. In this work, aluminium boride, AlB2, has been investigated as a boron source for the formation of borohydrides under hydrogen pressures of p(H2) = 100 or 600 bar at elevated temperatures (350 or 400 °C). The systems AlB2-MHx (M = Li, Na, Mg, Ca) have been investigated, producing LiBH4, NaBH4 and Ca(BH4)2, whereas the formation of Mg(BH4)2 was not observed at T = 400 °C and p(H2) = 600 bar. The formation of the metal borohydrides is confirmed by powder X-ray diffraction and infrared spectroscopy and the fraction of boron in AlB2 and M(BH4)x is determined quantitatively by (11)B MAS NMR. Hydrogenation for 12 h at T = 350-400 °C and p(H2) = 600 bar leads to the formation of substantial amounts of LiBH4 (38.6 mol%), NaBH4 (83.0 mol%) and Ca(BH4)2 (43.6 mol%).

  5. Electron momentum distribution and electronic response of ceramic borides

    NASA Astrophysics Data System (ADS)

    Heda, N. L.; Meena, B. S.; Mund, H. S.; Sahariya, Jagrati; Kumar, Kishor; Ahuja, B. L.

    2017-03-01

    Isotropic Compton profiles of transition metal based ceramics TaB and VB have been measured using 137Cs (661.65 keV) γ-ray Compton spectrometer. The experimental momentum densities are compared with those deduced using linear combination of atomic orbitals (LCAO) with Hartree-Fock (HF), density functional theory (DFT) with Wu-Cohen generalized gradient approximation (WCGGA) and also the hybridization of HF and DFT (namely B3PW and PBE0) schemes. It is found that LCAO-DFT-WCGGA scheme based profiles give an overall better agreement with the experimental data, for both the borides. In addition, we have computed the Mulliken's population (MP) charge transfer data, energy bands, density of states and Fermi surface topology of both the borides using full potential-linearized augmented plane wave (FP-LAPW) and LCAO methods with DFT-WCGGA scheme. Cross-overs of Fermi level by the energy bands corresponding to B-2p and valence d-states of transition metals lead to metallic character in both the compounds. Equal-valence-electron-density profiles and MP analysis suggest more ionic character of VB than that of TaB.

  6. First Principles Search for New Superconducting Layered Borides

    NASA Astrophysics Data System (ADS)

    Curtarolo, Stefano

    2007-11-01

    The identification of novel crystal structures is a fundamental step for predicting new stable compounds in alloys. While performing ab initio data mining of intermetallic compounds [1], we discover a new family of layered metal borides [2], of which MgB2 is one particular element (the new phases are called Metal Sandwich (MS)). Thermodynamic stability and electronic properties of these MS phases are investigated in details, leading to the prediction of a hypothetical novel superconductor MS-LiB [2,3]. Calculations show that the MS phases in the Li-B system exhibit electronic features similar to those of MgB2 [2,3] and CaC6 [4]. Although the predicted critical temperature of LiB is lower than that of MgB2 (references [4] and [5] for MS2-LiB and MS1-LiB, respectively), the peculiarities of MS-LiB in terms of electronic structure, layer arrangements and doping capabilities allow a lot of freedom in the search for higher Tc systems [5,6]. We acknowledge the Teragrid-Partnership for computational resources. Research supported by ONR and NSF. [1] Phys. Rev. Lett. 91, 135503 (2003). [2] Phys. Rev. B 73, 180501(R) (2006). [3] Phys. Rev. B 74, 224507 (2006). [4] Phys. Rev. B 75, 064510 (2007). [5] Phys. Rev. B 75, 144506 (2007). [6] A. N. Kolmogorov, M. Calandra, and S. Curtarolo, Engineering superconductors with ab initio methods: ternary metal borides, (2007).

  7. Discovery of elusive structures of multifunctional transition-metal borides

    NASA Astrophysics Data System (ADS)

    Liang, Yongcheng; Wu, Zhaobing; Yuan, Xun; Zhang, Wenqing; Zhang, Peihong

    2015-12-01

    A definitive determination of crystal structures is an important prerequisite for designing and exploiting new functional materials. Even though tungsten and molybdenum borides (TMBx) are the prototype for transition-metal light-element compounds with multiple functionalities, their elusive crystal structures have puzzled scientists for decades. Here, we discover that the long-assumed TMB2 phases with the simple hP3 structure (hP3-TMB2) are in fact a family of complex TMB3 polytypes with a nanoscale ordering along the axial direction. Compared with the energetically unfavorable and dynamically unstable hP3-TMB2 phase, the energetically more favorable and dynamically stable TMB3 polytypes explain the experimental structural parameters, mechanical properties, and X-ray diffraction (XRD) patterns better. We demonstrate that such a structural and compositional modification from the hP3-TMB2 phases to the TMB3 polytypes originates from the relief of the strong antibonding interaction between d electrons by removing one third of metal atoms systematically. These results resolve the longstanding structural mystery of this class of metal borides and uncover a hidden family of polytypic structures. Moreover, these polytypic structures provide an additional hardening mechanism by forming nanoscale interlocks that may strongly hinder the interlayer sliding movements, which promises to open a new avenue towards designing novel superhard nanocomposite materials by exploiting the coexistence of various polytypes.

  8. A cascade reaction: ring-opening insertion of dioxaphospholane into lutetium alkyl bonds.

    PubMed

    Johnson, Kevin R D; Hayes, Paul G

    2014-02-14

    Geometrically constrained dioxaphospholane rings were incorporated into a bis(phosphinimine)carbazole ligand (HL) in an effort to generate an ancillary ligand system that is capable of supporting reactive lutetium alkyl functionalities and resistant to cyclometalation reactivity. This new ligand was used to prepare a lutetium dialkyl species, LLu(CH2SiMe3)2; however, the complex exhibited low thermal stability at ambient temperature. This dialkyl compound was found to be highly susceptible to a cascading inter- and intramolecular reaction that resulted in the sole formation of an asymmetric bimetallic tetraalkoxide complex. The product of this reaction, generated by the ring-opening insertion of dioxaphospholane moieties into lutetium-carbon bonds, was characterized by multinuclear NMR spectroscopy and single crystal X-ray diffraction.

  9. Lutetium-177 DOTATATE Production with an Automated Radiopharmaceutical Synthesis System.

    PubMed

    Aslani, Alireza; Snowdon, Graeme M; Bailey, Dale L; Schembri, Geoffrey P; Bailey, Elizabeth A; Pavlakis, Nick; Roach, Paul J

    2015-01-01

    Peptide Receptor Radionuclide Therapy (PRRT) with yttrium-90 ((90)Y) and lutetium-177 ((177)Lu)-labelled SST analogues are now therapy option for patients who have failed to respond to conventional medical therapy. In-house production with automated PRRT synthesis systems have clear advantages over manual methods resulting in increasing use in hospital-based radiopharmacies. We report on our one year experience with an automated radiopharmaceutical synthesis system. All syntheses were carried out using the Eckert & Ziegler Eurotope's Modular-Lab Pharm Tracer® automated synthesis system. All materials and methods used were followed as instructed by the manufacturer of the system (Eckert & Ziegler Eurotope, Berlin, Germany). Sterile, GMP-certified, no-carrier added (NCA) (177)Lu was used with GMP-certified peptide. An audit trail was also produced and saved by the system. The quality of the final product was assessed after each synthesis by ITLC-SG and HPLC methods. A total of 17 [(177)Lu]-DOTATATE syntheses were performed between August 2013 and December 2014. The amount of radioactive [(177)Lu]-DOTATATE produced by each synthesis varied between 10-40 GBq and was dependant on the number of patients being treated on a given day. Thirteen individuals received a total of 37 individual treatment administrations in this period. There were no issues and failures with the system or the synthesis cassettes. The average radiochemical purity as determined by ITLC was above 99% (99.8 ± 0.05%) and the average radiochemical purity as determined by HPLC technique was above 97% (97.3 ± 1.5%) for this period. The automated synthesis of [(177)Lu]-DOTATATE using Eckert & Ziegler Eurotope's Modular-Lab Pharm Tracer® system is a robust, convenient and high yield approach to the radiolabelling of DOTATATE peptide benefiting from the use of NCA (177)Lu and almost negligible radiation exposure of the operators.

  10. Magneto-optical property of terbium-lutetium-aluminum garnet crystals

    NASA Astrophysics Data System (ADS)

    Man, Peiwen; Ma, Fengkai; Xie, Tao; Ding, Jingxin; Wu, Anhua; Su, Liangbi; Li, Huanying; Ren, Guohao

    2017-04-01

    Mixed terbium lutetium aluminum garnet Tb2.2Lu0.8Al5O12 (LuTAG) single crystal was grown by Czochralski technique successfully. The structure had been analyzed by X-ray diffraction. The paramagnetic behavior was observed in magnetic measurement. Magneto-optical properties and thermal conductivity of LuTAG had been studied in detail and compared with these of TGG sample. The crystal exhibited a high thermal conductivity and very high transmittance, particularly in visible and near-infrared region, indicating terbium-lutetium-aluminum garnet could be a potential magneto-optical material using in high-power laser system.

  11. Lutetium-doped EuO films grown by molecular-beam epitaxy

    SciTech Connect

    Melville, A.; Heeg, T.; Mairoser, T.; Schmehl, A.; Shai, D. E.; Monkman, E. J.; Harter, J. W.; Hollaender, B.; Schubert, J.; Shen, K. M.; Mannhart, J.; Schlom, D. G.

    2012-05-28

    The effect of lutetium doping on the structural, electronic, and magnetic properties of epitaxial EuO thin films grown by reactive molecular-beam epitaxy is experimentally investigated. The behavior of Lu-doped EuO is contrasted with doping by lanthanum and gadolinium. All three dopants are found to behave similarly despite differences in electronic configuration and ionic size. Andreev reflection measurements on Lu-doped EuO reveal a spin-polarization of 96% in the conduction band, despite non-magnetic carriers introduced by 5% lutetium doping.

  12. Microstructure and properties of laser-borided composite layers formed on commercially pure titanium

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    Laser-boriding was proposed in order to produce composite boride layers on commercially pure titanium. Three zones were observed in the microstructure: laser-borided re-melted zone (TiB, TiB2 and Tiα'-phase), heat affected zone (Tiα'-phase) and the substrate without heat treatment (Tiα-phase). The stick-like titanium borides occurred in the re-melted zone. In some areas, the tubular nature of titanium borides was visible. Among the sticks of titanium borides the needles of Tiα'-phase appeared. The high overlapping of multiple laser tracks (86%) caused the formation of uniform laser-alloyed layer in respect of the thickness. The microcracks and pores were not detected in the laser-borided composite layer. The high hardness of the re-melted zone (1250-1650 HV) was obtained. The hardness gradually decreased up to 250-300 HV in heat affected zone and up to about 200 HV in the substrate. In case of higher laser beam power used (1.95 kW), the re-melted zone was thicker and more homogeneous in respect of the microstructure and hardness. The craters obtained at the surface after the Rockwell C indentation test evidently revealed ideal cohesion of the laser-borided layer (HF1 standard). The significant increase in wear resistance of laser-borided composite layers was observed in comparison with commercially pure titanium. The lower mass wear intensity factors were obtained for laser-alloyed layers. The measurements of relative mass loss were also used in order to evaluate wear behavior of the investigated materials. The tests of laser-borided layers showed the catastrophic wear of the counter-specimens. The separated particles of counter-sample caused the accelerated wear of the laser-alloyed specimen. The longer duration of the tests, carried out without the change in a counter-specimen, caused the adhesion of counter-sample particles on the laser-borided specimen. The increased contact surface was the reason for the higher temperature and created the favourable

  13. Nanosized Borides and Carbides for Electroplating. Metal-Matrix Coatings: Specifications, Performance Evaluation

    NASA Astrophysics Data System (ADS)

    Galevskiy, G. V.; Rudneva, V. V.; Galevskiy, S. G.; Il'yashchenko, D. P.; Kartsev, D. S.

    2016-04-01

    This paper summarizes experience of application of nano-sized carbides and borides of titanium and chromium, silicon carbide as components of electro-depositable coating compositions based on nickel, zinc, and chromium. Basic physical and mechanical properties of the coatings are determined. Technological and economic evaluation is completed; practicability of high-cost nano-diamonds substitution for nano-sized borides and carbides is justified.

  14. An alternative method of gas boriding applied to the formation of borocarburized layer

    SciTech Connect

    Kulka, M. Makuch, N.; Pertek, A.; Piasecki, A.

    2012-10-15

    The borocarburized layers were produced by tandem diffusion processes: carburizing followed by boriding. An alternative method of gas boriding was proposed. Two-stage gas boronizing in N{sub 2}-H{sub 2}-BCl{sub 3} atmosphere was applied to the formation of iron borides on a carburized substrate. This process consisted in two stages, which were alternately repeated: saturation by boron and diffusion annealing. The microstructure and microhardness of produced layer were compared to those-obtained in case of continuous gas boriding in H{sub 2}-BCl{sub 3} atmosphere, earlier used. The first objective of two-stage boronizing, consisting in acceleration of boron diffusion, has been efficiently implemented. Despite the lower temperature and shorter duration of boronizing, about 1.5 times larger iron borides' zone has been formed on carburized steel. Second objective, the absolute elimination of brittle FeB phase, has failed. However, the amount of FeB phase has been considerably limited. Longer diffusion annealing should provide the boride layer with single-phase microstructure, without FeB phase. - Highlights: Black-Right-Pointing-Pointer Alternative method of gas boriding in H{sub 2}-N{sub 2}-BCl{sub 3} atmosphere was proposed. Black-Right-Pointing-Pointer The process consisted in two stages: saturation by boron and diffusion annealing. Black-Right-Pointing-Pointer These stages of short duration were alternately repeated. Black-Right-Pointing-Pointer The acceleration of boron diffusion was efficiently implemented. Black-Right-Pointing-Pointer The amount of FeB phase in the boride zone was limited.

  15. 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

  16. Lutetium-177 DOTATATE Production with an Automated Radiopharmaceutical Synthesis System

    PubMed Central

    Aslani, Alireza; Snowdon, Graeme M; Bailey, Dale L; Schembri, Geoffrey P; Bailey, Elizabeth A; Pavlakis, Nick; Roach, Paul J

    2015-01-01

    Objective(s): Peptide Receptor Radionuclide Therapy (PRRT) with yttrium-90 (90Y) and lutetium-177 (177Lu)-labelled SST analogues are now therapy option for patients who have failed to respond to conventional medical therapy. In-house production with automated PRRT synthesis systems have clear advantages over manual methods resulting in increasing use in hospital-based radiopharmacies. We report on our one year experience with an automated radiopharmaceutical synthesis system. Methods: All syntheses were carried out using the Eckert & Ziegler Eurotope’s Modular-Lab Pharm Tracer® automated synthesis system. All materials and methods used were followed as instructed by the manufacturer of the system (Eckert & Ziegler Eurotope, Berlin, Germany). Sterile, GMP-certified, no-carrier added (NCA) 177Lu was used with GMP-certified peptide. An audit trail was also produced and saved by the system. The quality of the final product was assessed after each synthesis by ITLC-SG and HPLC methods. Results: A total of 17 [177Lu]-DOTATATE syntheses were performed between August 2013 and December 2014. The amount of radioactive [177Lu]-DOTATATE produced by each synthesis varied between 10-40 GBq and was dependant on the number of patients being treated on a given day. Thirteen individuals received a total of 37 individual treatment administrations in this period. There were no issues and failures with the system or the synthesis cassettes. The average radiochemical purity as determined by ITLC was above 99% (99.8 ± 0.05%) and the average radiochemical purity as determined by HPLC technique was above 97% (97.3 ± 1.5%) for this period. Conclusions: The automated synthesis of [177Lu]-DOTATATE using Eckert & Ziegler Eurotope’s Modular-Lab Pharm Tracer® system is a robust, convenient and high yield approach to the radiolabelling of DOTATATE peptide benefiting from the use of NCA 177Lu and almost negligible radiation exposure of the operators. PMID:27408890

  17. Boron-Based Hydrogen Storage: Ternary Borides and Beyond

    SciTech Connect

    Vajo, John J.

    2016-04-28

    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 slow 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.

  18. Novel lutetium spectroscopic interactions via cw RIMS (Resonance Ionization Mass Spectrometry)

    SciTech Connect

    Fearey, B.L.; Miller, C.M.

    1989-01-01

    Novel spectroscopic interactions of argon-ion laser enhanced resonance ionization of lutetium are observed and discussed; these include line-narrowing, non-linear power dependences and anomalous optical pumping effects of the hyperfine transitions. In addition, isotopically saturation dip spectra are observed and presented, allowing for precise determination of hyperfine constants of rare isotopes. 12 refs., 2 figs.

  19. 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.

  20. Morphology and structure of borides in as-cast titanium and gamma-titanium aluminide-based alloys

    NASA Astrophysics Data System (ADS)

    Kitkamthorn, Usanee

    In this study, the morphology and structure of the borides in boron-modified Ti- and gamma-TiAl-based alloys have been investigated using SEM, TEM, and HRTEM. A variety of different boride morphologies was observed including plates, needles, and ribbons. For the plate and needle borides, the major boride phase is B27 TiB. The needle borides have their major axis parallel to [010], and are bounded by (100) and {101} type-facets. The plate borides develop the same types of facets as the needles and have habit planes parallel to the (100). There are high densities of intrinsic stacking faults on (100) in these borides and these correspond to thin embedded layers of the Bf structure. The plate borides do not exhibit well-defined ORs with respect to the surrounding phases, suggesting that they develop in the liquid melt and were then trapped by the growing solid. Needle borides are observed mostly at boundaries between lamellar colonies: these needles tend to occur in groups lying nearly parallel to one another and, in some cases, to adopt well-defined ORs with respect to the surrounding phases. Cored borides with metallic phases such as beta, alpha, o and alpha 2+gamma in the center are frequently observed, especially in the Ti-based alloy. These core phases usually adopt well-defined ORs with respect to the surrounding boride which enable low-energy coherent interfaces to form between the phases. The ribbon borides are comprised of thin boride flakes interspersed with thin metallic layers. The major boride phase in these flakes is Bf TiB. The habit plane of the flakes is (010) and there are high densities of faults on this plane corresponding to intergrowths of the Ti3B 4 and TiB2 phases, together with thin layers or occluded pockets of metallic B2 phase. Occasional faults are observed on {110} corresponding to embedded slabs of B27 TiB. There is a well-defined OR between the boride flakes and the B2 phase within the ribbons, but not with the surrounding matrix. The

  1. 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.

  2. Kinetics of borided 31CrMoV9 and 34CrAlNi7 steels

    SciTech Connect

    Efe, Goezde Celebi; Ipek, Mediha; Ozbek, Ibrahim; Bindal, Cuma

    2008-01-15

    In this study, kinetics of borides formed on the surface of 31CrMoV9 and 34CrAlNi7 steels borided in solid medium consisting of Ekabor II at 850-900-950 deg. C for 2, 4, 6 and 8 h were investigated. Scanning electron microscopy and optical microscopy examinations showed that borides formed on the surface of borided steels have columnar morphology. The borides formed in the coating layer confirmed by X-ray diffraction analysis are FeB, Fe{sub 2}B, CrB, and Cr{sub 2}B. The hardnesses of boride layers are much higher than that of matrix. It was found that depending on process temperature and time the fracture toughness of boride layers ranged from 3.93 to 4.48 MPa m{sup 1/2} for 31CrMoV9 and from 3.87 to 4.40 MPa m{sup 1/2} for 34CrAlNi7 steel. Activation energy, growth rate and growth acceleration of boride layer calculated according to these kinetic studies revealed that lower activation energy results in the fast growth rate and high growth acceleration.

  3. de Haas--van Alphen effect and Fermi surface of lutetium

    SciTech Connect

    Johanson, W.R.; Crabtree, G.W.; Schmidt, F.A.

    1984-03-01

    We report de Haas--van Alphen measurements of the Fermi surface of lutetium at temperatures down to 0.3 K and in fields up to 150 kG in the (1010) and (1120) planes. Lutetium, having a filled 4f shell, serves as a nonmagnetic prototype of the structurally similar (hcp), trivalent, heavy rare-earth elements from Gd to Tm. The fact that no complete frequency branches were observed indicates that there are no closed pieces of the Fermi surface. We observed all but one orbit predicted by relativistic augmented-plane-wave calculations of Keeton and Loucks and by recent spin-orbit--linearized-augmented-plane-wave calculations of Tibbetts and Harmon. The data support a geometry similar to that of yttrium, and in good qualitative agreement with energy-band theory.

  4. de Haas-van Alphen effect and Fermi surface of lutetium

    NASA Astrophysics Data System (ADS)

    Johanson, W. R.; Crabtree, G. W.; Schmidt, F. A.

    1984-03-01

    We report de Haas-van Alphen measurements of the Fermi surface of lutetium at temperatures down to 0.3 K and in fields up to 150 kG in the (101¯0) and (112¯0) planes. Lutetium, having a filled 4f shell, serves as a nonmagnetic prototype of the structurally similar (hcp), trivalent, heavy rare-earth elements from Gd to Tm. The fact that no complete frequency branches were observed indicates that there are no closed pieces of the Fermi surface. We observed all but one orbit predicted by relativistic augmented-plane-wave calculations of Keeton and Loucks and by recent spin-orbit-linearized-augmented-plane-wave calculations of Tibbetts and Harmon. The data support a geometry similar to that of yttrium, and in good qualitative agreement with energy-band theory.

  5. Novel functionalized mesopore of SBA-15 as prospective sorbent for praseodymium and lutetium.

    PubMed

    Mallah, M H; Ghannadi Maragheh, M; Badiei, A; Habibzadeh Sbo, R

    In the present work, results of γ-irradiation on normal and functionalized SBA-15 by aurintricarboxylic acid have been reported. Characterization of normal and functionalized SBA-15 particles before and after γ-irradiation was carried out using Fourier-transform infrared technique. Aurintricarboxylic acid ligand connected to SBA-15 was also analyzed using UV/Vis spectrophotometer. The modified sorbent was then used as a new sorbent for separation of trace amounts of praseodymium and lutetium ions from nuclear waste waters in batch techniques. Based on the results of distribution coefficients determination, and investigation of sorption process in various conditions, the parameters were optimized for separation lanthanides. It can be concluded that the functionalized SBA-15 is a promising sorbent for praseodymium and lutetium cations.

  6. Heteroleptic naphthalo-phthalocyaninates of lutetium: synthesis and spectral and conductivity properties.

    PubMed

    Dubinina, Tatiana V; Kosov, Anton D; Petrusevich, Elizaveta F; Maklakov, Sergey S; Borisova, Nataliya E; Tomilova, Larisa G; Zefirov, Nikolay S

    2015-05-07

    Novel heteroleptic naphthalo-phthalocyaninates of lutetium possessing a symmetrical substituted naphthalocyanine deck were synthesized on the basis of two preformed synthetic blocks: naphthalocyanine ligand and lutetium phthalocyaninates. The compounds obtained were characterized by (1)H NMR and high-resolution MALDI-TOF/TOF mass spectrometry. The correlation between the nature of the substituents and the spectral properties of the target complexes was determined by the introduction of electron-donating (aryl-, aryloxy-) or electron-withdrawing (chloro-) substituents into the phthalocyanine deck. In addition, the nature of peripheral substituents was shown not to affect drastically the phthalocyanine conductivity and activation energy. Conductivity properties depend on thin film morphology which, in turn, relies on intermolecular π-π interactions.

  7. Properties of Ce-activated alkali-lutetium double phosphate scintillators

    SciTech Connect

    Wiśniewski, D.; Wojtowicz, A. J.; Boatner, Lynn A

    2010-01-01

    The scintillation properties of Ce-activated alkali-lutetium double phosphate single crystals that vary with the alkali ion type and activation level are summarized and compared. The materials investigated here have been identified as fast and efficient scintillators for the detection of x-ray and radiation, and in case of Li3Lu(PO4)2:Ce, for thermal neutron detection as well.

  8. Lutetium(iii) aqua ion: On the dynamical structure of the heaviest lanthanoid hydration complex

    NASA Astrophysics Data System (ADS)

    Sessa, Francesco; Spezia, Riccardo; D'Angelo, Paola

    2016-05-01

    The structure and dynamics of the lutetium(iii) ion in aqueous solution have been investigated by means of a polarizable force field molecular dynamics (MD). An 8-fold square antiprism (SAP) geometry has been found to be the dominant configuration of the lutetium(iii) aqua ion. Nevertheless, a low percentage of 9-fold complexes arranged in a tricapped trigonal prism (TTP) geometry has been also detected. Dynamic properties have been explored by carrying out six independent MD simulations for each of four different temperatures: 277 K, 298 K, 423 K, 632 K. The mean residence time of water molecules in the first hydration shell at room temperature has been found to increase as compared to the central elements of the lanthanoid series in agreement with previous experimental findings. Water exchange kinetic rate constants at each temperature and activation parameters of the process have been determined from the MD simulations. The obtained structural and dynamical results suggest that the water exchange process for the lutetium(iii) aqua ion proceeds with an associative mechanism, in which the SAP hydration complex undergoes temporary structural changes passing through a 9-fold TTP intermediate. Such results are consistent with the water exchange mechanism proposed for heavy lanthanoid atoms.

  9. Lutetium(iii) aqua ion: On the dynamical structure of the heaviest lanthanoid hydration complex.

    PubMed

    Sessa, Francesco; Spezia, Riccardo; D'Angelo, Paola

    2016-05-28

    The structure and dynamics of the lutetium(iii) ion in aqueous solution have been investigated by means of a polarizable force field molecular dynamics (MD). An 8-fold square antiprism (SAP) geometry has been found to be the dominant configuration of the lutetium(iii) aqua ion. Nevertheless, a low percentage of 9-fold complexes arranged in a tricapped trigonal prism (TTP) geometry has been also detected. Dynamic properties have been explored by carrying out six independent MD simulations for each of four different temperatures: 277 K, 298 K, 423 K, 632 K. The mean residence time of water molecules in the first hydration shell at room temperature has been found to increase as compared to the central elements of the lanthanoid series in agreement with previous experimental findings. Water exchange kinetic rate constants at each temperature and activation parameters of the process have been determined from the MD simulations. The obtained structural and dynamical results suggest that the water exchange process for the lutetium(iii) aqua ion proceeds with an associative mechanism, in which the SAP hydration complex undergoes temporary structural changes passing through a 9-fold TTP intermediate. Such results are consistent with the water exchange mechanism proposed for heavy lanthanoid atoms.

  10. Biomimetic biosensor based on lipidic layers containing tyrosinase and lutetium bisphthalocyanine for the detection of antioxidants.

    PubMed

    Apetrei, C; Alessio, P; Constantino, C J L; de Saja, J A; Rodriguez-Mendez, M L; Pavinatto, F J; Ramos Fernandes, E Giuliani; Zucolotto, V; Oliveira, O N

    2011-01-15

    This paper describes the preparation of a biomimetic Langmuir-Blodgett film of tyrosinase incorporated in a lipidic layer and the use of lutetium bisphthalocyanine as an electron mediator for the voltammetric detection of phenol derivatives, which include one monophenol (vanillic acid), two diphenols (catechol and caffeic acid) and two triphenols (gallic acid and pyrogallol). The first redox process of the voltammetric responses is associated with the reduction of the enzymatically formed o-quinone and is favoured by the lutetium bisphthalocyanine because significant signal amplification is observed, while the second is associated with the electrochemical oxidation of the antioxidant and occurs at lower potentials in the presence of an electron mediator. The biosensor shows low detection limit (1.98×10(-6)-27.49×10(-6) M), good reproducibility, and high affinity to antioxidants (K(M) in the range of 62.31-144.87 μM). The excellent functionality of the enzyme obtained using a biomimetic immobilisation method, the selectivity afforded by enzyme catalysis, the signal enhancement caused by the lutetium bisphthalocyanine mediator and the increased selectivity of the curves due to the occurrence of two redox processes make these sensors exceptionally suitable for the detection of phenolic compounds. Copyright © 2010 Elsevier B.V. All rights reserved.

  11. Absolute peptide quantification by lutetium labeling and nanoHPLC-ICPMS with isotope dilution analysis.

    PubMed

    Rappel, Christina; Schaumlöffel, Dirk

    2009-01-01

    The need of analytical methods for absolute quantitative protein analysis spurred research on new developments in recent years. In this work, a novel approach was developed for accurate absolute peptide quantification based on metal labeling with lutetium diethylenetriamine pentaacetic acid (Lu-DTPA) and nanoflow high-performance liquid chromatography-inductively coupled plasma isotope dilution mass spectrometry (nanoHPLC-ICP-IDMS). In a two-step procedure peptides were derivatized at amino groups with diethylenetriamine pentaacetic anhydride (DTPAA) followed by chelation of lutetium. Electrospray ionization mass spectrometry (ESI MS) of the reaction product demonstrated highly specific peptide labeling. Under optimized nanoHPLC conditions the labeled peptides were baseline-separated, and the excess labeling reagent did not interfere. A 176Lu-labeled spike was continuously added to the column effluent for quantification by ICP-IDMS. The recovery of a Lu-DTPA-labeled standard peptide was close to 100% indicating high labeling efficiency and accurate absolute quantification. The precision of the entire method was 4.9%. The detection limit for Lu-DTPA-tagged peptides was 179 amol demonstrating that lutetium-specific peptide quantification was by 4 orders of magnitude more sensitive than detection by natural sulfur atoms present in cysteine or methionine residues. Furthermore, the application to peptides in insulin tryptic digest allowed the identification of interfering reagents decreasing the labeling efficiency. An additional advantage of this novel approach is the analysis of peptides, which do not naturally feature ICPMS-detectable elements.

  12. 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.

  13. 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.

  14. 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.

  15. Characterization of novel borides in Ti-Nb-Zr-Ta + 2B metal-matrix composites

    SciTech Connect

    Nag, Soumya; Samuel, Sonia; Puthucode, Anantha; Banerjee, Rajarshi

    2009-02-15

    Metal-matrix composites consisting of a complex quaternary Ti-35Nb-7Zr-5Ta alloy reinforced by borides have been successfully deposited from a powder feedstock consisting of a blend of elemental titanium, niobium, zirconium, tantalum, and, titanium diboride (TiB{sub 2}) powders, using the laser engineered net-shaping (LENS{sup TM}) process. The microstructures of the as-deposited composites have been characterized using scanning electron microscopy, orientation microscopy, and, transmission electron microscopy. Both primary and eutectic boride precipitates, exhibiting the orthorhombic B27 structure, are observed in these as-deposited composites. The complex primary borides exhibit an unusual compositional variation within the same precipitate, which has been investigated in detail using site-specific characterization with a transmission electron microscope. The ability to form near-net shape components using the Laser Engineered Net Shaping process makes these laser-deposited composites promising candidates for wear-resistant applications in biomedical implants.

  16. Modeling of the electron-beam boriding in the system Fe-B-C-O2

    NASA Astrophysics Data System (ADS)

    Dasheev, D. E.; Smirnyagina, N. N.

    2017-05-01

    This paper reviews the conditions of iron borides formation and simulation of surface layers saturation depending on the stoichiometry of original components. Temperature fields have been investigated as well, which form certain phases in accordance with the pressure in the chamber and the power of the electron beam. A thermodynamic study of phase equilibria in Fe-B-C-O systems has been performed. This was done in order to optimize conditions for forming functional layers on the surface of iron-carbon alloys as a result of electron beam boriding in vacuum. Furthermore, strength characteristics of iron boride layers have been determined. Then these layers obtained by different methods and using various source components have been thoroughly compared with each other during the analysis.

  17. Boride-based nano-laminates with MAX-phase-like behaviour

    SciTech Connect

    Telle, Rainer . E-mail: telle@ghi.rwth-aachen.de; Momozawa, Ai; Music, Denis; Schneider, Jochen M.

    2006-09-15

    MAX-phases being usually composed of transition metals, group A elements and carbon/nitrogen are considered interesting materials for many applications because of their tremendous bulk modulus, 'reversible' plasticity, and machinability. This is mainly due to their unique kind of bonding comprising covalent, ionic as well as metallic bonds providing 'easy' planes of rupture and deformability due to the layered crystal structures. In transition metal boride systems, similar types of bonding are available. In particular the W{sub 2}B{sub 5}-structure type and its stacking variations allow the synthesis of strongly layered crystal structures exhibiting unique delamination phenomena. The paper presents ab initio calculations showing the similarities of bonding between the ternary carbides and the corresponding ternary or quaternary borides. Formation of boride-based nano-laminates from auxiliary liquid phases, from the melt as well as during sintering and precipitation from supersaturated solid solutions will be discussed by means of SEM and TEM studies. The role of impurities weakening the interlayer bonding will be addressed in particular. The pronounced cleavage parallel to the basal plane gives rise for crack deflection and pull-out mechanisms if the laminates are dispersed in brittle matrices such as boron carbide, silicon carbide or other transition metal borides. - Graphical abstract: Some transition metal borides crystallise in a layered structure of alternating stacks of metal and boron atoms giving rise for strongly anisotropic properties. Their preferred cleavage parallel and the deformability perpendicular to the basal plan are similar to the peculiar mechanical behaviour recently described for MAX-phases. Ab initio calculations of the crystal structure prove the weak bonds between the layers for a variety of borides which can be used to reinforce ceramic materials on a nano-scale level.

  18. Surface hardening of steel by boriding in a cold rf plasma

    NASA Technical Reports Server (NTRS)

    Finberg, I.; Avni, R.; Grill, A.; Spalvins, T.; Buckley, D. H.

    1985-01-01

    Scanning electron spectroscopy, X-ray diffractometry, Auger electron spectroscopy, and microhardness measurements, are used to study the surfaces of 4340-steel samples that have been borided in a cold RF plasma which had been initiated in a gas mixture of 2.7 percent diborane in Ar. As a result of the dislocation of the diborane in the plasma, boron is deposited on the surface of the steel substrate and two crystalline phases, tetragonal Fe2B and orthorhombic FeB, are formed. The formation of boride phases then increases the surface microhardness from 2650 MPa to a maximum value of 7740 MPa.

  19. Surface hardening of steel by boriding in a cold rf plasma

    NASA Technical Reports Server (NTRS)

    Finberg, I.; Avni, R.; Grill, A.; Spalvins, T.; Buckley, D. H.

    1985-01-01

    Scanning electron spectroscopy, X-ray diffractometry, Auger electron spectroscopy, and microhardness measurements, are used to study the surfaces of 4340-steel samples that have been borided in a cold RF plasma which had been initiated in a gas mixture of 2.7 percent diborane in Ar. As a result of the dislocation of the diborane in the plasma, boron is deposited on the surface of the steel substrate and two crystalline phases, tetragonal Fe2B and orthorhombic FeB, are formed. The formation of boride phases then increases the surface microhardness from 2650 MPa to a maximum value of 7740 MPa.

  20. Surface hardening of St41 low carbon steel by using the hot-pressing powder-pack boriding method

    NASA Astrophysics Data System (ADS)

    Sutrisno, Soegijono, Bambang

    2014-03-01

    This research describes a powder-pack boriding process by using hot-pressing technic for St41 low carbon steel which will improve the hardness on the substrate by forming boride layer solid solution. Those method can reduce the operational cost of the research if it is compared by the conventional method with the asmospheric condition both vacuum system and gas inert condition. The concept of boriding by hot-pressing technic was verified in a laboratory scale. Welldefined and reusedable technic was achieved by using the stainless steel 304 as the container and sealed with a 5 ton pressure. This container was filled boronizing powder consisting of 5%B4C, 90%SiC, and 5%KBF4 to close the St41 low carbon steel specimen inside the container. The St41 boriding specimen was treated at the temperature of 900°C for 8 hours. The boride layer on the substrate was found as FeB and Fe2B phase with the hardness about 1800 HV. This value was more than ten times if compared with the untreated specimen that only had the hardness of 123 HV. Depend on heat treatment temperature, heat treatment time, and powder-pack boriding pressure, the depth of boride layer range from 127 to 165 μm, leading to a diffusion controlled process.

  1. Metal-boride phase formation on tungsten carbide (WC-Co) during microwave plasma chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Johnston, Jamin M.; Catledge, Shane A.

    2016-02-01

    Strengthening of cemented tungsten carbide by boriding is used to improve the wear resistance and lifetime of carbide tools; however, many conventional boriding techniques render the bulk carbide too brittle for extreme conditions, such as hard rock drilling. This research explored the variation in metal-boride phase formation during the microwave plasma enhanced chemical vapor deposition process at surface temperatures from 700 to 1100 °C. We showed several well-adhered metal-boride surface layers consisting of WCoB, CoB and/or W2CoB2 with average hardness from 23 to 27 GPa and average elastic modulus of 600-730 GPa. The metal-boride interlayer was shown to be an effective diffusion barrier against elemental cobalt; migration of elemental cobalt to the surface of the interlayer was significantly reduced. A combination of glancing angle X-ray diffraction, electron dispersive spectroscopy, nanoindentation and scratch testing was used to evaluate the surface composition and material properties. An evaluation of the material properties shows that plasma enhanced chemical vapor deposited borides formed at substrate temperatures of 800 °C, 850 °C, 900 °C and 1000 °C strengthen the material by increasing the hardness and elastic modulus of cemented tungsten carbide. Additionally, these boride surface layers may offer potential for adhesion of ultra-hard carbon coatings.

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

    SciTech Connect

    Kon, O.; Pazarlioglu, 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 measurements 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}.

  3. 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.

  4. Structures and stability of novel transition-metal (M =Co ,Rh ,Co and Ir ) borides

    NASA Astrophysics Data System (ADS)

    Wang, Yachun; Wu, Lailei; Lin, Yangzheng; Hu, Qingyang; Li, Zhiping; Liu, Hanyu; Zhang, Yunkun; Gou, Huiyang; Yao, Yansun; Zhang, Jingwu; Gao, Faming; Mao, Ho-kwang

    2015-11-01

    Recent progress of high-pressure technology enables the synthesis of novel metal borides with diverse compositions and interesting properties. A precise characterization of these borides, however, is sometimes hindered by multiphase intergrowth and grain-size limitation in the synthesis process. Here, we theoretically explored new transition-metal borides (M =Co , Rh, and Ir) using a global structure searching method and discovered a series of stable compounds in this family. The predicted phases display a rich variety of stoichiometries and distinct boron networks resulting from the electron-deficient environments. Significantly, we identified a new Ir B1.25 structure as the long-sought structure of the first synthesized Ir-B compound. The simulated x-ray diffraction pattern of the proposed Ir B1.25 structure matches well with the experiment, and the convex hull calculation establishes its thermodynamic stability. Results of the present paper should advance the understanding of transition-metal borides and stimulate experimental explorations of these new and promising materials.

  5. Ultra-Fast Boriding in High-Temperature Materials Processing Industries

    SciTech Connect

    2008-12-01

    This factsheet describes a research project whose main objective is to further develop, optimize, scale-up, and commercialize an ultra-fast boriding (also referred to as “boronizing”) process that can provide much higher energy efficiency, productivity, and near-zero emissions in many of the high-temperature materials processing industries.

  6. Synthesis of Lutetium Phosphate/Apoferritin Core-Shell Nanoparticles for Potential Applications in Radioimmunoimaging and Radioimmunotherapy of Cancers

    SciTech Connect

    Wu, Hong; Engelhard, Mark H.; Wang, Jun; Fisher, Darrell R.; Lin, Yuehe

    2008-04-01

    We report a novel approach for synthesizing LuPO4/apoferritin core-shell nanoparticles based on an apoferritin template, conjugated to the protein biotin. To prepare the nanoparticle conjugates, we used non-radioactive lutetium as a model target or surrogate for radiolutetium (177Lu). The central cavity, multi-channel structure, and chemical properties of apoferritin are well-suited for sequentially diffusing lutetium and phosphate ions into the cavity--resulting in a stable core-shell composite. We characterized the synthesized LuPO4/apoferritin nanoparticle using transmission electron microscopy (TEM) and x-ray photoelectron spectroscopy (XPS). We tested the pre-targeting capability of biotin-modified lutetium/apoferritin nanoparticle using streptavidin-modified magnetic beads and streptavidin-modified fluorescein isothiocyanate (FITC) tracer. This paper presents a simple, fast, and efficient method for synthesizing LuPO4/apoferritin nanoparticle conjugates with biotin for potential applications in radioimmunotherapy and radioimmunoimaging of cancer.

  7. Additive-assisted synthesis of boride, carbide, and nitride micro/nanocrystals

    SciTech Connect

    Chen, Bo; Yang, Lishan; Heng, Hua; Chen, Jingzhong; Zhang, Linfei; Xu, Liqiang; Qian, Yitai; Yang, Jian

    2012-10-15

    General and simple methods for the syntheses of borides, carbides and nitrides are highly desirable, since those materials have unique physical properties and promising applications. Here, a series of boride (TiB{sub 2}, ZrB{sub 2}, NbB{sub 2}, CeB{sub 6}, PrB{sub 6}, SmB{sub 6}, EuB{sub 6}, LaB{sub 6}), carbide (SiC, TiC, NbC, WC) and nitride (TiN, BN, AlN, MgSiN{sub 2}, VN) micro/nanocrystals were prepared from related oxides and amorphous boron/active carbon/NaN{sub 3} with the assistance of metallic Na and elemental S. In-situ temperature monitoring showed that the reaction temperature could increase quickly to {approx}850 Degree-Sign C, once the autoclave was heated to 100 Degree-Sign C. Such a rapid temperature increase was attributed to the intense exothermic reaction between Na and S, which assisted the formation of borides, carbides and nitrides. The as-obtained products were characterized by XRD, SEM, TEM, and HRTEM techniques. Results in this report will greatly benefit the future extension of this approach to other compounds. - Graphical abstract: An additive-assisted approach is successfully developed for the syntheses of borides, carbides and nitrides micro/nanocrystals with the assistance of the exothermic reaction between Na and S. Highlights: Black-Right-Pointing-Pointer An additive-assisted synthesis strategy is developed for a number of borides, carbides and nitrides. Black-Right-Pointing-Pointer The reaction mechanism is demonstrated by the case of SiC nanowires. Black-Right-Pointing-Pointer The formation of SiC nanowires is initiated by the exothermic reaction of Na and S.

  8. Potential and limitations of microanalysis SEM techniques to characterize borides in brazed Ni-based superalloys

    SciTech Connect

    Ruiz-Vargas, J.; Siredey-Schwaller, N.; Noyrez, P.; Mathieu, S.; Bocher, P.; and others

    2014-08-15

    Brazed Ni-based superalloys containing complex phases of different Boron contents remain difficult to characterize at the micrometer scale. Indeed Boron is a light element difficult to measure precisely. The state-of-the-art microanalysis systems have been tested on a single crystal MC2 based metal brazed with BNi-2 alloy to identify boride precipitates. Effort has been made to evaluate the accuracy in Boron quantitation. Energy-dispersive and wavelength-dispersive X-ray spectroscopy attached to a Scanning Electron Microscope have first been used to determine the elemental composition of Boron-free phases, and then applied to various types of borides. Results have been compared to the ones obtained using a dedicated electron probe microanalysis, considered here as the reference technique. The most accurate method to quantify Boron using EDS is definitely by composition difference. A precision of 5 at.% could be achieved with optimized data acquisition and post-processing schemes. Attempts that aimed at directly quantifying Boron with various standards using EDS or coupled EDS/WDS gave less accurate results. Ultimately, Electron Backscatter Diffraction combined with localized EDS analysis has proved invaluable in conclusively identifying micrometer sized boride precipitates; thus further improving the characterization of brazed Ni-based superalloys. - Highlights: • We attempt to accurately identify Boron-rich phases in Ni-based superalloys. • EDS, WDS, EBSD systems are tested for accurate identification of these borides. • Results are compared with those obtained by electron probe microanalysis. • Boron was measured with EDS by composition difference with a precision of 5 at. %. • Additional EBSD in phase identification mode conclusively identifies the borides.

  9. Phase I trial of motexafin-lutetium-mediated interstitial photodynamic therapy in patients with locally recurrent prostate cancer

    NASA Astrophysics Data System (ADS)

    Stripp, Diana C. H.; Mick, Rosemarie; Zhu, Timothy C.; Whittington, Richard; Smith, Debbie; Dimofte, Andreea; Finlay, Jarod C.; Miles, Jeremy; Busch, Theresa M.; Shin, Daniel; Kachur, Alex; Tochner, Zelig A.; Malkowicz, S. Bruce; Glatstein, Eli; Hahn, Stephen M.

    2004-06-01

    Therapeutic options for patients with locally recurrent prostate cancer after treatment with radiation therapy are limited. An ongoing Phase I trial of interstitial photodynamic therapy (PDT) with the photosensitizer motexafin lutetium (MLu) was initiated in year 2000 for men with locally recurrent prostate cancer. The primary objective of this trial is to determine the maximally tolerated dose of motexafin lutetium-mediated PDT. Twelve men with biopsy-proven recurrent prostate cancer and no evidence of distant metastatic disease have been enrolled. Pre-treatment evaluation included an MRI of the prostate, bone scan, laboratory studies, cystoscopy, and transrectal ultrasound. Treatment plans were generated based upon the ultrasound findings. PDT dose was escalated by increasing the motexafin lutetium dose, increasing the 732 nm light dose, and decreasing the drug-light interval. Motexafin lutetium doses ranged from 0.5 to 2 mg/kg administered IV 3, 6, or 24 hours prior to 732 nm light delivery. The light dose measured in real time with in situ spherical detectors was 25-100 J/cm2 for all patients. Light was delivered through optical fibers inserted through a transperineal brachytherapy template in the operating room and optical property measurements were made before and after light therapy. Prostate biopsies were obtained before and after light delivery for spectrofluorometric measurements of photosensitizer uptake. Twelve patients have completed protocol treatment on eight dose levels without dose-limiting toxicity. Grade I PDT-related genitourinary symptoms were observed. One patient had Grade II urinary urgency that was urinary catheter-related. No rectal or other GI PDT-related toxicities were observed. Measurements of motexafin lutetium in prostate tissue demonstrated the presence of photosensitizer at all dose levels. Conclusions: Motexafin lutetium-mediated PDT designed to treat comprehensively the entired prostate gland has been well-tolerated at the doses

  10. Growth of epitaxial bismuth and gallium substituted lutetium iron garnet films by pulsed laser deposition

    SciTech Connect

    Leitenmeier, Stephan; Heinrich, Andreas; Lindner, Joerg K. N.; Stritzker, Bernd

    2006-04-15

    Epitaxial bismuth and gallium substituted lutetium iron garnet thin films have been grown on (100) oriented gadolinium gallium garnet Gd{sub 3}Ga{sub 5}O{sub 12} substrates by pulsed laser deposition. The films have been studied using x-ray diffraction, high resolution x-ray diffraction, Rutherford backscattering spectroscopy, transmission electron microscopy, and electron diffraction. We obtained smooth films with thicknesses between 0.3 and 1.0 {mu}m showing good crystalline quality and epitaxial growth.

  11. Syntheses and structures of mononuclear lutetium imido complexes with very short Lu-N bonds.

    PubMed

    Panda, Tarun K; Randoll, Sören; Hrib, Cristian G; Jones, Peter G; Bannenberg, Thomas; Tamm, Matthias

    2007-12-21

    The reaction of 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-imine (ImDippNH) with trimethylsilylmethyllithium and anhydrous lutetium trichloride affords the imido complex [LuCl2(ImNDipp)(THF)3], which, on further reaction with dipotassium cyclooctatetraenide, K2(C8H8), leads to the half-sandwich cyclooctatetraenyl complex [(eta8-C8H8)Lu(ImNDipp)(THF)2]; both complexes contain very short Lu-N bond lengths, which are shorter than any previously reported Lu-N distances.

  12. Evaluation of the tool life and fracture toughness of cutting tools boronized by the paste boriding process

    NASA Astrophysics Data System (ADS)

    Campos, I.; Farah, M.; López, N.; Bermúdez, G.; Rodríguez, G.; VillaVelázquez, C.

    2008-03-01

    The present study evaluates the tool life and the fracture toughness of AISI M2 steel cutting tools boronized by the paste boriding process. The treatment was done in selective form on the tool tips of the steels. The temperatures were set at 1173 and 1273 K with 4 h of exposure time and modifying the boron carbide paste thicknesses in 3 and 4 mm. Microindentation fracture toughness method was used on the borided tool at the temperature of 1273 K and a 4 mm paste thickness, with a 100 g load at different distances from the surface. Also, the borided cutting tools were worn by the turning process that implied the machining of AISI 1018 steel increasing the nominal cutting speed, of 55 m/min, in 10 and 25% and maintaining the feed and the depth cut constants. The tool life was evaluated by the Taylor's equation that shows the dependence of the experimental parameters of the boriding process.

  13. A kinetic model for estimating the boron activation energies in the FeB and Fe2B layers during the gas-boriding of Armco iron: Effect of boride incubation times

    NASA Astrophysics Data System (ADS)

    Keddam, M.; Kulka, M.; Makuch, N.; Pertek, A.; Małdziński, L.

    2014-04-01

    The present work deals with a simulation of the growth kinetics of boride layers grown on Armco iron substrate. The formed boride layers (FeB + Fe2B) are obtained by the gas-boriding in the temperature range of 1073-1273 K during a time duration ranging from 80 to 240 min. The used approach solves the mass balance equations at the two growing fronts: (FeB/Fe2B) and (Fe2B/Fe) under certain assumptions. To consider the effect of the incubation times for the borides formation, the temperature-dependent function Φ(T) was incorporated in the model. The following input data: (the boriding temperature, the treatment time, the upper and lower values of boron concentrations in FeB and Fe2B and the experimental parabolic growth constants) are needed to determine the boron activation energies in the FeB and Fe2B layers. The obtained values of boron activation energies were then compared with the values available in the literature. Finally, a good agreement was obtained between the simulated values of boride layers thicknesses and the experimental ones in the temperature range of 1073-1273 K.

  14. Electrochromic and gas adsorption properties of Langmuir-Blodgett films of lutetium bisphthalocyanine complexes

    SciTech Connect

    Rodriguez-Mendez, M.L.; Aroca, R. ); DeSaja, J.A. )

    1993-07-01

    The electrochromic behaviour, spectroscopic properties and gas chemisorption of ultra thin films of lutetium octa-4-phenyldiphthalocyanine (LuPc[sub 2][sup Ph]), and the lutetium octa-3-bromo-octa-5-tert-butylphthalocyanine (LuPc[sub 2][sup tBr]) are reported. Electrochromism was observed for Langmuir-Blodgett (LB) and films cast onto indium tin oxide (ITO) coated glass electrodes in aqueous KClO[sub 4] solution. Mixed LB films supported on ITO glass electrodes were more stable to repetitive cycling than cast films. Films of LuPc[sub 2][sup Ph] and LuPc[sub 2][sup tBr] were sensitive to electron-acceptor gases as observed by the changes in the electronic absorption spectra and the surface-enhanced resonance Raman scattering (SERRS) spectra. The presence of electron-withdrawing bromine atoms in the phthalocyanine ring increased the rate of desorption for chemisorbed electron-acceptor molecules. 10 refs., 8 figs., 3 tabs.

  15. Lutetium(III) acetate phthalocyanines for photodynamic therapy applications: Synthesis and photophysicochemical properties.

    PubMed

    Mantareva, Vanya; Durmuş, Mahmut; Aliosman, Meliha; Stoineva, Ivanka; Angelov, Ivan

    2016-06-01

    The development of new water-soluble photosensitizers for photodynamic therapy (PDT) applications is a very active research topic. Efforts have been made to obtain the far-red absorbing phthalocyanine complexes with molecular design that facilitates the uptake and selectivity for a high PDT efficiency. The monomolecular lutetium(III) acetate phthalocyanines (LuPcs) substituted with methylpyridyloxy groups at non-peripheral (5) and peripheral (6) positions were synthesized by following the modification of the well-known synthetical routes. The photo-physicochemical properties of the both quaternized LuPcs were evaluated by the steady-state and time-resolved spectroscopy. The photochemical technique was applied to study the generation of the singlet oxygen. Two water-soluble and cationic LuPcs were synthesized and chemically characterized. The photo-physicochemical properties of absorption (675 and 685nm) and the red shifted fluorescence (704 and 721nm) as well as the fluorescence lifetimes (2.24 and 3.27ns) were studied. The promising values of singlet oxygen quantum yields (0.32 for 5 and 0.35 for 6) were determined. Lutetium(III) acetate phthalocyanine complexes were synthesized and evaluated with physicochemical properties suitable for future photodynamic therapy applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Lutetium alkyl and hydride complexes in a non-cyclopentadienyl coordination environment.

    PubMed

    Konkol, Marcin; Spaniol, Thomas P; Kondracka, Małgorzata; Okuda, Jun

    2007-09-28

    Lutetium alkyl complexes [Lu(L)(CH(2)SiMe(3))(THF)(n)], which contain a sulfur-linked bis(phenolato) ligand such as 2,2'-thiobis(6-tert-butyl-4-methylphenolate) (L=tbmp, 1) or 1,4-dithiabutanediyl-bis(6-tert-butyl-4-methylphenolate) (L=etbmp, 2), were isolated from the reaction of the lutetium tris(alkyl) complex [Lu(CH(2)SiMe(3))(3)(THF)(2)] with H(2)L. The monomeric structures of these complexes were confirmed by X-ray diffraction studies, showing distorted octahedral geometry around the metal centre. The reaction of [Lu(tbmp)(CH(2)SiMe(3))(THF)(2)] (1) with alcohols ROH (R=iPr, CHPh(2), CPh(3)) results in the formation of the corresponding alkoxide complexes [Lu(tbmp)(OR)(THF)(n)] (4-6). With PhSiH(3) hydride complexes [Lu(L)(mu-H)(THF)(n)](2) (L=tbmp, 7; etbmp, 8) have been prepared in moderate to good yields. They adopt a dimeric form in the solid state as revealed by the X-ray crystal structure of 7. The reactivity of the hydride complexes and their catalytic activity in the ring-opening polymerisation of L-lactide and the hydrosilylation of alkenes are also discussed.

  17. On the photoelectron velocity-map imaging of lutetium monoxide anion LuO(-).

    PubMed

    Liu, Zhiling; Xie, Hua; Li, Quanjiang; Qin, Zhengbo; Cong, Ran; Wu, Xia; Tang, Zichao; Fan, Hongjun

    2014-01-21

    We report a combined photoelectron velocity-map imaging spectroscopy and density functional theory investigation on lutetium monoxide anion. Transition between the X (1)Σ(+) anion electronic ground state and the neutral X (2)Σ(+) electronic ground state is observed. Vibrationally resolved spectra were obtained at four different photon energies, providing a wealth of spectroscopic information for the electronic ground states of the anionic lutetium monoxide and corresponding neutral species. Franck-Condon simulations of the ground-state transition are performed to assign vibrational structure in the spectra and to assist in identifying the observed spectral bands. The electronic ground state of LuO(-) is found to have a vibrational frequency of 743 ± 10 cm(-1) and an equilibrium bond length of 1.841 Å. The electron affinity of LuO is measured to be 1.624 ± 0.002 eV. The fundamental frequency of ground-state LuO is estimated to be 839 ± 10 cm(-1).

  18. On the photoelectron velocity-map imaging of lutetium monoxide anion LuO{sup −}

    SciTech Connect

    Liu, Zhiling; Xie, Hua; Qin, Zhengbo; Cong, Ran; Wu, Xia; Tang, Zichao Fan, Hongjun; Li, Quanjiang

    2014-01-21

    We report a combined photoelectron velocity-map imaging spectroscopy and density functional theory investigation on lutetium monoxide anion. Transition between the X {sup 1}Σ{sup +} anion electronic ground state and the neutral X {sup 2}Σ{sup +} electronic ground state is observed. Vibrationally resolved spectra were obtained at four different photon energies, providing a wealth of spectroscopic information for the electronic ground states of the anionic lutetium monoxide and corresponding neutral species. Franck-Condon simulations of the ground-state transition are performed to assign vibrational structure in the spectra and to assist in identifying the observed spectral bands. The electronic ground state of LuO{sup −} is found to have a vibrational frequency of 743 ± 10 cm{sup −1} and an equilibrium bond length of 1.841 Å. The electron affinity of LuO is measured to be 1.624 ± 0.002 eV. The fundamental frequency of ground-state LuO is estimated to be 839 ± 10 cm{sup −1}.

  19. Lutetium texaphyrin (Lu-Tex): a potential new agent for ocular fundus angiography and photodynamic therapy.

    PubMed

    Blumenkranz, M S; Woodburn, K W; Qing, F; Verdooner, S; Kessel, D; Miller, R

    2000-03-01

    To investigate the suitability of lutetium texaphyrin (lu-tex) as a fluorescence imaging agent in the delineation of retinal vascular and choroidal vascular diseases. The utilization of an efficient fluorescent molecule that is also a photosensitizer represents a unique opportunity to couple diagnosis and therapy. Fundus fluorescence angiography comparing lu-tex (motexafin lutetium, Optrin, Pharmacyclics Inc, Sunnyvale, California) with the conventional angiographic dyes, sodium fluorescein, and indocynanine green (ICG), was performed on the eyes of normal and laser-injured New Zealand white rabbits. Plasma pharmacokinetic data and plasma protein binding were assessed in addition to light microscopy of the retina in both imaged and laser-injured eyes. Normal retinal and choroidal vasculature was well delineated by lu-tex angiography. Experimentally induced choroidal and retinal vascular lesions were enhanced by lu-tex and demonstrated different staining patterns than fluorescein or ICG, particularly at the margins of the lesions. Lu-tex cleared rapidly from the plasma, with 39.7% bound to the high-density lipoprotein (HDL) fraction while 15.8% was bound to the low-density lipoprotein (LDL) fraction. No evidence of retinal toxicity after dye administration was observed by either ophthalmoscopy and fundus photography or by light microscopy. Lu-tex angiography is a potentially valuable method for retinal vascular and choroidal vascular evaluation, and it has advantages over fluorescein and ICG angiography. The same agent could conceivably be used for both the identification of abnormal vasculature and subsequent photodynamic treatment.

  20. Atomic and electronic structures of lutetium oxide Lu{sub 2}O{sub 3}

    SciTech Connect

    Kaichev, V. V.; Asanova, T. I.; Erenburg, S. B.; Perevalov, T. V.; Shvets, V. A.; Gritsenko, V. A.

    2013-02-15

    The chemical composition, electronic structure, structure, and physical properties a lutetium oxide Lu{sub 2}O{sub 3} film are studied by X-ray photoelectron spectroscopy, ellipsometry, and X-ray absorption spectroscopy. The short-range order in Lu{sub 2}O{sub 3} is found to correspond to its cubic modification. The binding energies of the 1s and 2p levels of oxygen and the 4d{sub 5/2} and 4f{sub 7/2} levels of lutetium are 529.2, 5.0 and 7.4, 195.9 eV, respectively. The energy gap determined from the electron energy loss spectrum of the film is 5.9 eV. The electron energy loss spectra have two peaks at 17.4 and 22.0 eV, which can be attributed to the excitation of bulk plasma oscillations. The dispersion of the refractive index is measured by spectral ellipsometry. The refractive index is shown to increase from 1.82 at 1.5 eV to 2.18 at 5.0 eV, and the high-frequency permittivity of Lu{sub 2}O{sub 3} is 3.31.

  1. Improving the Adhesion Resistance of the Boride Coatings to AISI 316L Steel Substrate by Diffusion Annealing

    NASA Astrophysics Data System (ADS)

    Campos-Silva, I.; Bernabé-Molina, S.; Bravo-Bárcenas, D.; Martínez-Trinidad, J.; Rodríguez-Castro, G.; Meneses-Amador, A.

    2016-09-01

    In this study, new results about the practical adhesion resistance of boride coating/substrate system formed at the surface of AISI 316 L steel and improved by means of a diffusion annealing process are presented. First, the boriding of AISI 316 L steel was performed by the powder-pack method at 1173 K with different exposure times (4-8 h). The diffusion annealing process was conducted on the borided steels at 1273 K with 2 h of exposure using a diluent atmosphere of boron powder mixture. The mechanical behavior of the boride coating/substrate system developed by both treatments was established using Vickers and Berkovich tests along the depth of the boride coatings, respectively. Finally, for the entire set of experimental conditions, the scratch tests were performed with a continuously increasing normal force, in which the practical adhesion resistance of the boride coating/substrate system was represented by the critical load. The failure mechanisms developed over the surface of the scratch tracks were analyzed; the FeB-Fe2B/substrate system exhibited an adhesive mode, while the Fe2B/substrate system obtained by the diffusion annealing process showed predominantly a cohesive failure mode.

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

    PubMed Central

    2014-01-01

    Background 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. Results 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. Conclusions This study is, to our knowledge, the first to identify peptides that

  3. Inclusion complexes of trivalent lutetium cations with an acidic derivative of per(3,6-anhydro)-alpha-cyclodextrin.

    PubMed

    Bonnet, Célia; Gadelle, Andrée; Pécaut, Jacques; Fries, Pascal H; Delangle, Pascale

    2005-02-07

    The cyclodextrin derivative (hexakis (2-O-carboxymethyl-3,6-anhydro)-alpha-cyclodextrin) forms mono- and bimetallic complexes with lutetium(III) in aqueous solution; the X-ray structure of the binuclear complex [Lu2(ACX)(H2O)2] is the first example of a lanthanide-cyclodextrin inclusion complex.

  4. 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.

  5. Adsorption of micelle-forming surfactants from aqueous solutions on disperse titanium boride

    SciTech Connect

    Grodskii, A.S.; Komleva, E.A.; Frolov, Yu.G.

    1988-08-10

    Adsorption studies showed that nonionogenic and cationic surfactants are adsorbed on the surface of disperse titanium boride. Anionic surfactants are virtually not adsorbed due to the negative charge of the particles. It was found that in the region of low concentrations of surfactants in the solution, adsorption of Sintanols takes place in lyophobic regions and the surface of the particles becomes hydrophilic. The Sintamid molecules are adsorbed on the entire interface, including both hydrophobic and hydrophilic sections, with subsequent formation of bimolecular layers by adsorption on hydrophobic sections. Catamine-AB is adsorbed on hydrophilic sections of the surface also with the formation of bimolecular layers. Developed polymolecular layers up to 10-15 nm thick are formed on titanium boride particles from micellar solutions of nonionigenic and cationic surfactants.

  6. Boriding 5khNM hot-working dies in coatings

    SciTech Connect

    Luk'yanov, V.P.; Mitrokhovich, N.N.; Polovnikov, V.M.

    1983-03-01

    The life of the forging die determines the effectiveness of close died forging methods. Boron impregnation expands the life of the die. Tests were run on boriding pastes where boron carbide is the supplier of active boron and cryolite the binder and activator. High cryolite results in the highest boron impregnation activity but must be kept in ratio to the boron. The establishment of the chemical mechanism of the paste discovers 3-5 sodium flouride along with cryolite and boron, from which an optimum composition at 860 C for 4h. is determined. The optimum thickness of the layer should be 3-5mm, less not being thick enough, more causing runoff and oxidation. Steel impregnated with boron paste was then tested for erosion, with good results. Boriding in the coating of forging dies, now in use at the Lepse South Kama Plant, is recommended.

  7. 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.

  8. Synthesis and Characterization of an Alumina Forming Nanolaminated Boride: MoAlB

    PubMed Central

    Kota, Sankalp; Zapata-Solvas, Eugenio; Ly, Alexander; Lu, Jun; Elkassabany, Omar; Huon, Amanda; Lee, William E.; Hultman, Lars; May, Steve J.; Barsoum, Michel W.

    2016-01-01

    The ‘MAlB’ phases are nanolaminated, ternary transition metal borides that consist of a transition metal boride sublattice interleaved by monolayers or bilayers of pure aluminum. However, their synthesis and properties remain largely unexplored. Herein, we synthesized dense, predominantly single-phase samples of one such compound, MoAlB, using a reactive hot pressing method. High-resolution scanning transmission electron microscopy confirmed the presence of two Al layers in between a Mo-B sublattice. Unique among the transition metal borides, MoAlB forms a dense, mostly amorphous, alumina scale when heated in air. Like other alumina formers, the oxidation kinetics follow a cubic time-dependence. At room temperature, its resistivity is low (0.36–0.49 μΩm) and – like a metal – drops linearly with decreasing temperatures. It is also a good thermal conductor (35 Wm−1K−1 at 26 °C). In the 25–1300 °C temperature range, its thermal expansion coefficient is 9.5 × 10−6 K−1. Preliminary results suggest the compound is stable to at least 1400 °C in inert atmospheres. Moderately low Vickers hardness values of 10.6 ± 0.3 GPa, compared to other transition metal borides, and ultimate compressive strengths up to 1940 ± 103 MPa were measured at room temperature. These results are encouraging and warrant further study of this compound for potential use at high temperatures. PMID:27220751

  9. Influence of Re Concentration on the Mechanical Properties of Tungsten Borides from First-Principles Calculations

    NASA Astrophysics Data System (ADS)

    Pan, Yong; Lin, Yuanhua

    2017-10-01

    Tungsten borides are promising high-temperature materials. However, the structure and hardening mechanisms of tungsten boride are still great challenges. To solve the problems, we apply the first-principles method to study the structure of WB3 and explore the influence of alloying element Re on the mechanical properties of WB3. The calculated Vickers hardness of WB3 is 39.1 GPa. We further find that a low concentration of Re can improve the hardness of WB3, which is in good agreement with the experimental result. However, the hardness and elastic properties of WB3 decrease gradually with increasing Re concentration. The calculated results show that the structure and hardness of WB3 are attributed to the B-B hexagonal prism. A high concentration of Re weakens the charge interaction between the B-B atoms, and reduces the mechanical properties of WB3. Therefore, we can adjust the alloy concentration to improve the Vickers hardness of transition metal borides.

  10. Synthesis and characterization of noble metal borides: RuB{sub x}(x > 1)

    SciTech Connect

    Li, Zhifang; Zheng, Dafang; Ding, Zhanhui; Li, Yongfeng; Yao, Bin; Li, Yongsheng; Zhao, Xudong; Yu, Guichuan; Tang, Yang; Zheng, Weitao; Liu, Xiaoyang

    2016-02-15

    Highlights: • Hexagonal RuB{sub 1.1} were synthesized using ruthenium and boron powders as raw materials during ball milling process. • Orthorhombic RuB{sub 2} were synthesized under high pressure (5 GPa) and high temperature (1000 °C) conditions. • Hexagonal Ru{sub 2}B{sub 3} have been synthesized under 5 GPa and 1200 °C. - Abstract: Noble metal borides RuB{sub 1.1}, RuB{sub 2} and Ru{sub 2}B{sub 3} have been synthesized by mechanical alloying and high pressure sintering methods using ruthenium (Ru) and boron (B) powders as raw materials. The crystal structures of borides were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results shown that only RuB{sub 1.1} with hexagonal crystal structure was synthesized during the ball milling process, the orthorhombic RuB{sub 2} was synthesized under high pressure (5 GPa) and high temperature (1000 °C) conditions, while the hexagonal Ru{sub 2}B{sub 3} can be synthesized under 5 GPa and 1200 °C. The mechanism of synthesis for the ruthenium borides (RuB{sub x}) are discussed in details.

  11. Structure of superhard tungsten tetraboride: a missing link between MB2 and MB12 higher borides.

    PubMed

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

    2015-03-17

    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 W(1-x)B3--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 polyhedral--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.

  12. Influence of Re Concentration on the Mechanical Properties of Tungsten Borides from First-Principles Calculations

    NASA Astrophysics Data System (ADS)

    Pan, Yong; Lin, Yuanhua

    2017-08-01

    Tungsten borides are promising high-temperature materials. However, the structure and hardening mechanisms of tungsten boride are still great challenges. To solve the problems, we apply the first-principles method to study the structure of WB3 and explore the influence of alloying element Re on the mechanical properties of WB3. The calculated Vickers hardness of WB3 is 39.1 GPa. We further find that a low concentration of Re can improve the hardness of WB3, which is in good agreement with the experimental result. However, the hardness and elastic properties of WB3 decrease gradually with increasing Re concentration. The calculated results show that the structure and hardness of WB3 are attributed to the B-B hexagonal prism. A high concentration of Re weakens the charge interaction between the B-B atoms, and reduces the mechanical properties of WB3. Therefore, we can adjust the alloy concentration to improve the Vickers hardness of transition metal borides.

  13. 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

  14. Low temperature route for the synthesis of rare earth transition metal borides and their hydrides

    SciTech Connect

    Kramp, S.; Febri, M.; Joubert, J.C.

    1997-10-01

    Synthesis of rare earth-based alloys by the ORD technique consists in the reduction of rare earth oxides in a melt of calcium under argon, and simultaneous diffusion-reaction of the just formed rare earth metal with the other elements. This method has been applied with success to numerous ternary borides containing transition metals such as the magnetic alloys Y{sub 2}Co{sub 14}B, LnCo{sub 4}B, and YCo{sub 3}B{sub 2}. By using a small excess of Ca, boride particles grow in a viscous slurry media containing unreacted (melted) Ca and nanosize CaO particles. Single phase boride alloys can be obtained at 1000{degrees}C as loose micrometer-size particles of very high crystal quality as confirmed by the sharp diffraction peaks on the corresponding X-ray diagrams. Particles can be easily recovered by gentle wishing in diluted weak acid solution, and dried under vacuum at room temperature. This rather low temperature technique is particularly adapted to the synthesis of incongruent melting phases, as well as for the alloys containing volatile rare earth elements (Sm, Yb, Tb,...).

  15. A Low Temperature Route for the Synthesis of Rare Earth Transition Metal Borides and Their Hydrides

    NASA Astrophysics Data System (ADS)

    Kramp, S.; Febri, M.; Joubert, J. C.

    1997-10-01

    Synthesis of rare earth-based alloys by the ORD technique consists in the reduction of rare earth oxides in a melt of calcium under argon, and simultaneous diffusion-reaction of the just formed rare earth metal with the other elements. This method has been applied with success to numerous ternary borides containing transition metals such as the magnetic alloys Y2Co14B, LnCo4B, and YCo3B2. By using a small excess of Ca, boride particles grow in a viscous slurry media containing unreacted (melted) Ca and nanosize CaO particles. Single phase boride alloys can be obtained at 1000°C as loose micrometer-size particles of very high crystal quality as confirmed by the sharp diffraction peaks on the corresponding X-ray diagrams. Particles can be easily recovered by gentle washing in diluted weak acid solution, and dried under vacuum at room temperature. This rather low temperature technique is particularly adapted to the synthesis of incongruent melting phases, as well as for the alloys containing volatile rare earth elements (Sm, Yb, Tb,…).

  16. Distinct surface hydration behaviors of boron-rich boride thin film coatings

    NASA Astrophysics Data System (ADS)

    Lu, Xinhong; Liu, Wei; Ouyang, Jun; Tian, Yun

    2014-08-01

    In this work, the surface boron chemical states and surface hydration behaviors of the as-deposited and annealed boron-rich boride thin film coatings, including AlMgB14, TiB2 and AlMgB14-TiB2, were systematically studied by use of X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The XPS results indicate that boron at annealed AlMgB14 film surface can be oxidized; surprisingly, such oxidation does not lead to the formation of boric acid in ambient air. Instead, boric acid can be produced at the surface of annealed TiB2 film and AlMgB14-TiB2 film. It is shown, via the water contact angle measurements, that these boride films exhibit distinct surface wettability characteristics, which are believed to result in the observed surface hydration processes. Furthermore, we found anatase TiO2 formation plays a major role in the surface wetting behaviors for these boride films.

  17. 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.

  18. Corrosion behavior of titanium boride composite coating fabricated on commercially pure titanium in Ringer's solution for bioimplant applications.

    PubMed

    Sivakumar, Bose; Singh, Raghuvir; Pathak, Lokesh Chandra

    2015-03-01

    The boriding of commercially pure titanium was performed at 850°C, 910°C, and 1050°C for varied soaking periods (1, 3 and 5h) to enhance the surface properties desirable for bioimplant applications. The coating developed was characterized for the evolution of phases, microstructure and morphology, microhardness, and consequent corrosion behavior in the Ringer's solution. Formation of the TiB2 layer at the outermost surface followed by the TiB whiskers across the borided CpTi is unveiled. Total thickness of the composite layer on the substrates borided at 850, 910, and 1050°C for 5h was found to be 19.1, 26.4, and 18.2μm respectively which includes <3μm thick TiB2 layer. The presence of TiB2 phase was attributed to the high hardness ~2968Hv15gf of the composite coating. The anodic polarization studies in the simulated body fluid unveiled a reduction in the pitting corrosion resistance after boriding the CpTi specimens. However, this value is >0.55VSCE (electrochemical potential in in-vivo physiological environment) and hence remains within the safe region. Both the untreated and borided CpTi specimens show two passive zones associated with different passivation current densities. Among the CpTi borided at various times and temperatures, a 3h treated shows better corrosion resistance. The corrosion of borided CpTi occurred through the dissolution of TiB2. Copyright © 2014. Published by Elsevier B.V.

  19. Photoelectric conversion and electrochromic properties of lutetium tetrakis(tert-butyl)bisphthalocyaninate

    SciTech Connect

    Hu, Andrew Teh; Hu Tenyi; Liu Lungchang

    2003-12-10

    Both photoelectric and electrochromic effects on lutetium tetrakis(tert-butyl)bisphthalocyaninate (Lu(TBPc){sub 2}) have been carried out in this study. Lu(TBPc){sub 2} is known for its electrochromic performance, but its photoelectric effect has not mentioned in the literature. The electrochromic properties of Lu(TBPc){sub 2} have been measured by cyclic voltammetry (CV) and UV-Vis spectrometer at the same time. It takes less than 1.5 s for the color to change from red to green under 0.9 V. Its cycle life is at least over 500 times. Furthermore, we also investigate its photoelectric conversion properties. Its photoelectric cell exhibits a positive photo-electricity conversion effect with a short-circuit photocurrent (46.4 {mu}A/cm{sup 2}) under illumination of white light (1.201 mW/cm{sup 2})

  20. Vacuum ultraviolet field emission lamp consisting of neodymium ion doped lutetium fluoride thin film as phosphor.

    PubMed

    Yanagihara, Masahiro; Tsuji, Takayuki; Yusop, Mohd Zamri; Tanemura, Masaki; Ono, Shingo; Nagami, Tomohito; Fukuda, Kentaro; Suyama, Toshihisa; Yokota, Yuui; Yanagida, Takayuki; Yoshikawa, Akira

    2014-01-01

    A vacuum ultraviolet (VUV) field emission lamp was developed by using a neodymium ion doped lutetium fluoride (Nd(3+) : LuF3) thin film as solid-state phosphor and carbon nanofiber field electron emitters. The thin film was synthesized by pulsed laser deposition and incorporated into the lamp. The cathodoluminescence spectra of the lamp showed multiple emission peaks at 180, 225, and 255 nm. These emission spectra were in good agreement with the spectra reported for the Nd(3+) : LuF3 crystal. Moreover, application of an acceleration voltage effectively increased the emission intensity. These results contribute to the performance enhancement of the lamp operating in the VUV region.

  1. Photoemission spectroscopy study of the lanthanum lutetium oxide/silicon interface

    SciTech Connect

    Nichau, A.; Schnee, M.; Schubert, J.; Bernardy, P.; Hollaender, B.; Buca, D.; Mantl, S.; Besmehn, A.; Breuer, U.; Rubio-Zuazo, J.; Castro, G. R.; Muecklich, A.; Borany, J. von

    2013-04-21

    Rare earth oxides are promising candidates for future integration into nano-electronics. A key property of these oxides is their ability to form silicates in order to replace the interfacial layer in Si-based complementary metal-oxide field effect transistors. In this work a detailed study of lanthanum lutetium oxide based gate stacks is presented. Special attention is given to the silicate formation at temperatures typical for CMOS processing. The experimental analysis is based on hard x-ray photoemission spectroscopy complemented by standard laboratory experiments as Rutherford backscattering spectrometry and high-resolution transmission electron microscopy. Homogenously distributed La silicate and Lu silicate at the Si interface are proven to form already during gate oxide deposition. During the thermal treatment Si atoms diffuse through the oxide layer towards the TiN metal gate. This mechanism is identified to be promoted via Lu-O bonds, whereby the diffusion of La was found to be less important.

  2. Vacuum Ultraviolet Field Emission Lamp Consisting of Neodymium Ion Doped Lutetium Fluoride Thin Film as Phosphor

    PubMed Central

    Yanagihara, Masahiro; Tsuji, Takayuki; Yusop, Mohd Zamri; Tanemura, Masaki; Nagami, Tomohito; Fukuda, Kentaro; Suyama, Toshihisa; Yokota, Yuui; Yanagida, Takayuki; Yoshikawa, Akira

    2014-01-01

    A vacuum ultraviolet (VUV) field emission lamp was developed by using a neodymium ion doped lutetium fluoride (Nd3+ : LuF3) thin film as solid-state phosphor and carbon nanofiber field electron emitters. The thin film was synthesized by pulsed laser deposition and incorporated into the lamp. The cathodoluminescence spectra of the lamp showed multiple emission peaks at 180, 225, and 255 nm. These emission spectra were in good agreement with the spectra reported for the Nd3+ : LuF3 crystal. Moreover, application of an acceleration voltage effectively increased the emission intensity. These results contribute to the performance enhancement of the lamp operating in the VUV region. PMID:25302320

  3. Half-life measurements of lutetium-176 using underground HPGe-detectors.

    PubMed

    Hult, Mikael; Vidmar, Tim; Rosengård, Ulf; Marissens, Gerd; Lutter, Guillaume; Sahin, Namik

    2014-05-01

    The half-life of (176)Lu was determined by measuring the (176)Lu activity in metallic lutetium foils. Three different HPGe-detectors located 225 m underground were employed for the study. Measurements using the sum-peak method were performed and resulted in an average massic activity of (52.61±0.36) Bq g(-1). The foils were of natural isotopic abundance so using the massic activity and the value of the natural isotopic abundance of (2.59±0.01)%, a half-life of (3.722±0.029)×10(10)a could be calculated. © 2013 Elsevier Ltd. All rights reserved.

  4. Formulation and characterization of lutetium-177-labeled stannous (tin) colloid for radiosynovectomy.

    PubMed

    Arora, Geetanjali; Singh, Manoranjan; Jha, Pragati; Tripathy, Sarthak; Bal, Chandrasekhar; Mukherjee, Anirban; Shamim, Shamim A

    2017-07-01

    Easy large-scale production, easy availability, cost-effectiveness, long half-life, and favorable radiation characteristics have made lutetium-177 (Lu) a preferred radionuclide for use in therapy. Lutetium-177-labeled stannous (Lu-Sn) colloid particles were formulated for application in radiosynovectomy, followed by in-vitro and in-vivo characterization. Stannous chloride (SnCl2) solution and Lu were heated together, the pH was adjusted, and the particles were recovered by centrifugation. The heating time and amount of SnCl2 were varied to optimize the labeling protocol. The labeling efficiency (LE) and radiochemical purity (RCP) of the product were determined. The size and shape of the particles were determined by means of electron microscopy. In-vitro stability was tested in PBS and synovial fluid, and in-vivo stability was tested in humans. LE and RCP were greater than 95% and ∼99% (Rf=0-0.1), respectively. Aggregated colloidal particles were spherical (mean size: 241±47 nm). The product was stable in vitro for up to 7 days in PBS as well as in synovial fluid. Injection of the product into the infected knee joint of a patient resulted in its homogenous distribution in the intra-articular space, as seen on the scan. No leakage of activity was seen outside the knee joint even 7 days after injection, indicating good tracer binding and in-vivo stability. Lu-Sn colloid was successfully prepared with a high LE (>95%) and high RCP (99%) under optimized reaction conditions. Because of the numerous benefits of Lu and the ease of preparation of tin colloid particles, Lu-Sn colloid particles are significantly superior to its currently available counterparts for use in radiosynovectomy.

  5. Mechanistic considerations of the pyrolytic formation of metal boride thin films by chemical vapor deposition from borane precursors

    SciTech Connect

    Tan, Y.; Kher, S.S.; Spencer, J.T.

    1995-12-31

    The formation of metal boride thin films by CVD is an area of potentially significant technological consequence. Interest in these materials is primarily due to their breadth of unique physical properties and to their wide structural diversity. Recently, we have explored the use of a number of boron-containing CVC precursors to prepare a wide variety of both pure metal and metal boride thin film materials. The highly efficient formation of polycrystalline transition metal and lanthanide metal boride thin films from borane precursors has now been well demonstrated through this CVD chemistry. The fundamentally important chemical processes and reactions in the CVD of boranes in forming metal boride films has, however, remained mostly a mystery. In order to rationally design new precursors and tailor the deposited solid state materials, an understanding of these fundamental processes is critical. In our recent work, which will be reported here, we have begun detailed mechanistic studies into the CVD of metal borides. These reactions have been found to occur both in the gas phase and on the surface of the reactor. A variety of studies have provided valuable insights into these complexes chemical reactions including labeling, thermal, product distribution, surface analysis, kinetic and other investigations.

  6. Effect of High Configuration Entropy and Rare Earth Addition on Boride Precipitation and Mechanical Properties of Multi-principal-Element Alloys

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Zhong, X. C.; He, Y. Z.; Li, W. H.; Wu, W. F.; Chen, G.; Guo, S.

    2017-08-01

    A series of multi-principal-element (MPE) alloys have been prepared by adding Ni, Mn, Al, Cu and Y into the reference CoCrFe-B alloy. The microstructure and mechanical properties of these MPE alloys have been investigated thoroughly. It is found that the addition of the elements can inhibit boride precipitation in the designed alloys and the solid solution strengthening effect induced by interstitial boron atoms is more significant than that by boride precipitation. The MPE alloys with the fcc phase as the main solid solution phase have a higher boron solubility and hence less boride precipitation, than those with the bcc phase as the main solid solution phase. The addition of yttrium can improve the boron solubility, decrease boride precipitation, control the boride morphology and, importantly, simultaneously improve the compressive strength and ductility of boron-containing MPE alloys.

  7. A new coprecipitation methodology with lutetium hydroxide for preconcentration of heavy metal ions in herbal plant samples.

    PubMed

    Soylak, Mustafa; Murat, Ipek

    2014-01-01

    A new coprecipitation methodology that used lutetium hydroxide as a precipitant for Cu(II), Pb(II), Mn(II), Co(II), Cd(II), Fe(III), and Ni(II) ions in herbal plant and water samples for analysis by atomic absorption spectrometry has been investigated. The parameters such as pH, amount of lutetium, and volume of aqueous sample were optimized for the recovery of these seven metals. The effects of concomitant ions on the separation-preconcentration of analytes were also checked. The validation of the procedure was checked with addition recovery tests and analysis of Standard Reference Material 1570a-Trace Elements in Spinach Leaves and TMDA-70 fortified lake water Certified Reference Material. The LODs for analyte ions were in the range of 1.7-7.2 microg/L. The application of the present procedure was successfully performed for the analysis of analyte contents of herbal plant samples from Turkey.

  8. Rare-earth antisites in lutetium aluminum garnets: Influence on lattice parameter and Ce3+ multicenter structure

    NASA Astrophysics Data System (ADS)

    Przybylińska, H.; Wittlin, A.; Ma, Chong-Geng; Brik, M. G.; Kamińska, A.; Sybilski, P.; Zorenko, Yu.; Nikl, M.; Gorbenko, V.; Fedorov, A.; Kučera, M.; Suchocki, A.

    2014-07-01

    Low temperature, infrared transmission spectra of lutetium aluminum garnet (LuAG) bulk crystals and epitaxial layers doped with Ce are presented. In the region of intra-configurational 4f-4f transitions the spectra of the bulk LuAG crystal exhibit the signatures of several different Ce3+ related centers. Apart from the dominant center, associated with Ce substituting lutetium, at least six other centers are found, some of them attributed to so-called antisite locations of rare-earth ions in the garnet host, i.e., ions in the Al positions. X-ray diffraction data prove lattice expansion of bulk LuAG crystals due presence of rare-earth antisites.

  9. Features of the spectral dependences of transmittance of organic semiconductors based on tert-butyl substituted lutetium phthalocyanine molecules

    SciTech Connect

    Belogorokhov, I. A.; Tikhonov, E. V.; Dronov, M. A.; Belogorokhova, L. I.; Ryabchikov, Yu. V.; Tomilova, L. G.; Khokhlov, D. R.

    2011-11-15

    Vibronic properties of organic semiconductors based on tert-butyl substituted phthalocyanine lutetium diphthalocyanine molecules are studied by IR and Raman spectroscopy. It is shown that substitution of several carbon atoms in initial phthalocyanine (Pc) ligands with {sup 13}C isotope atoms causes a spectral shift in the main absorption lines attributed to benzene, isoindol, and peripheral C-H groups. A comparison of spectral characteristics showed that the shift can vary from 3 to 1 cm{sup -1}.

  10. A Study of the Physical and Mechanical Properties of Lutetium Compared with Those of Transition Metals: A Data Mining Approach

    NASA Astrophysics Data System (ADS)

    Settouti, Nadera; Aourag, Hafid

    2015-01-01

    In this article, we study the physical and mechanical properties of lutetium, which will be compared with the elements of the third-row transition metals (Cs, Ba, Hf, Ta, W, Re, Os, Ir, Pt, Au, Tl, Pb, and Bi). Data mining is an ideal approach for analyzing the information and exploring the hidden knowledge among the data. The purpose of the data mining scheme is to identify and classify the effects of the relationships existing between properties. The results of the investigation are presented by means of multivariate modeling methods, such as the principal component analysis and the partial least squares regression to discover the implicit, yet meaningful, relationship between the elements of the data set, and to locate correlations between the properties of the materials. In this study, we present a data mining approach to discover such unusual correlations between properties of the elements. When comparing the properties of the transition metals with those of lutetium, our results show that lutetium shares many properties and similarities with the transition metals of the sixth row in the periodic table and can be well described as a transition metal.

  11. 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.

  12. Photodynamic therapy with motexafin lutetium for rectal cancer: a preclinical model in the dog.

    PubMed

    Ross, H M; Smelstoys, J A; Davis, G J; Kapatkin, A S; Del Piero, F; Reineke, E; Wang, H; Zhu, T C; Busch, T M; Yodh, A G; Hahn, S M

    2006-10-01

    Local recurrence of rectal cancer remains a significant clinical problem despite multi-modality therapy. Photodynamic Therapy (PDT) is a cancer treatment which generates tumor kill through the production of singlet oxygen in cells containing a photosensitizing drug when exposed to laser light of a specific wavelength. PDT is a promising modality for prevention of local recurrence of rectal cancer for several reasons: tumor cells may selectively retain photosensitizer at higher levels than normal tissues, the pelvis after mesorectal excision is a fixed space amenable to intra-operative illumination, and PDT can generate toxicity in tissues up to 1 cm thick. This study evaluated the safety, tissue penetration of 730 nm light, normal tissue toxicity and surgical outcome in a dog model of rectal resection after motexafin lutetium-mediated photodynamic therapy. Ten mixed breed dogs were used. Eight dogs underwent proctectomy and low rectal end to end stapled anastomosis. Six dogs received the photosensitizing agent motexafin lutetium (MLu, Pharmacyclics, Inc., Sunnyvale, CA) of 2 mg/kg preoperatively and underwent subsequent pelvic illumination of the transected distal rectum of 730 nm light with light doses ranging from 0.5 J/cm(2) to 10 J/cm(2) three hours after drug delivery. Two dogs received light, but no drug, and underwent proctectomy and low-rectal stapled anastomosis. Two dogs underwent midline laparotomy and pelvic illumination. Light penetration in tissues was determined for small bowel, rectum, pelvic sidewall, and skin. Clinical outcomes were recorded. Animals were sacrificed at 14 days and histological evaluation was performed. All dogs recovered uneventfully. No dog suffered an anastomotic leak. Severe tissue toxicity was not seen. Histological findings at necropsy revealed mild enteritis in all dogs. The excitation light penetration depths were 0.46 +/- 0.18, 0.46 +/- 0.15, and 0.69 +/- 0.39 cm, respectively, for rectum, small bowel, and peritoneum in

  13. The melting behavior of lutetium aluminum perovskite LuAlO3

    NASA Astrophysics Data System (ADS)

    Klimm, Detlef

    2010-02-01

    DTA measurements with mixtures of aluminum oxide and lutetium oxide around the 1:1 perovskite composition were performed up to 1970C. A peak with onset 1901C was due to the melting of the eutectic Lu4Al2O9 (monoclinic phase) and LuAlO3 (perovskite). Neither peritectic melting of the perovskite nor its decomposition in the solid phase could be resolved experimentally. The maximum of the eutectic peak size is near x=0.44, on the Lu-rich side of the perovskite, which is consistent with the conclusion that LuAlO3 melts peritectically at ca. 1907C as proposed by Wu, Pelton, J. Alloys Compd. 179 (1992) 259. Thermodynamic equilibrium calculation reveals that under strongly reducing conditions (oxygen partial pressure <10-13 bar) aluminum(III) oxide can be reduced to suboxides or even Al metal. It is shown that under such conditions a new phase field with liquid Al can appear.

  14. Physical properties of zircon and scheelite lutetium orthovanadate: Experiment and first-principles calculation

    SciTech Connect

    Huang, Zuocai; Zhang, Lei; Pan, Wei

    2013-09-15

    Pure zircon and scheelite LuVO{sub 4} were prepared by solid state reaction and high-pressure route, respectively. Structure, elastic constants, lattice dynamics and thermodynamics of LuVO{sub 4} polymorphs were studied by experiments and first principles calculation. Calculations here are in good agreement with the experimental results. The phonon dispersions of LuVO{sub 4} polymorphs were studied by the linear response method. The calculated phonon dispersions show that zircon and scheelite LuVO{sub 4} phases are dynamically stable. Raman-active frequencies were measured and assigned to different modes according to the calculations. The internal frequencies shift downward after phase transition from zircon to scheelite. Born effective charge tensors elements for both phases are analyzed. The finite temperature thermodynamic properties of LuVO{sub 4} polymorphs were calculated from the obtained phonon density of states by quasi-harmonic approach. - Graphical abstract: Lutetium orthovanadate polymorphs were synthesized by SSR and HP methods and their physical and chemical properties, including lattice dynamical properties, were determined by DFT calculations and experiments. Display Omitted - Highlights: • Pure zircon and scheelite LuVO{sub 4} polymorphs were synthesized by solid state reaction and high-pressure route. • Chemical and physical properties of LuVO4 polymorphs were studied by experiments and first principles calculation. • Raman-active frequencies were measured and assigned to different modes according to the calculations. • Lattice dynamics of polymorphs were discussed in details.

  15. Lutetium 177-DOTA-TATE therapy for esthesioneuroblastoma: A case report

    PubMed Central

    Sabongi, Juliano Guerra; Gonçalves, Mônica Carboni Pereira; Alves, Cira Danielle Casado; Alves, João; Scapulatempo-Neto, Cristovam; Moriguchi, Sonia Marta

    2016-01-01

    Esthesioneuroblastoma (ENB), also known as olfactory neuroblastoma, is a rare malignant tumor that accounts for 3% of all tumors of the nasal cavity. The incidence of ENB is 0.4 cases per million in the general population, and the most common symptoms are nasal obstruction and epistaxis. Previous studies have indicated the presence of somatostatin receptors in this tumor type. Common treatment strategies for ENB include resection and adjuvant radiotherapy and/or chemotherapy (combined treatment); however, the rate of recurrence is high. Treatment of neuroendocrine tumors using radionuclides bound to somatostatin analogues is well established in clinical practice. However, a standard and effective therapeutic approach has not been reported for ENB. The current study described the case of a 74-year-old female with numerous recurrences of ENB following multiple treatments and without possibility of resection. The patient was treated with the radiolabeled-somatostatin analogue, 177Lutetium-DOTA-octreotate (177Lu-DOTA-TATE), which successfully controlled the disease. This suggests that 177Lu-DOTA-TATE is a potential treatment for ENB and may represent an effective alternative and novel therapeutic strategy for this disease. PMID:27882120

  16. Even-parity Rydberg and autoionizing states of lutetium by laser resonance-ionization spectroscopy

    NASA Astrophysics Data System (ADS)

    Li, R.; Lassen, J.; Zhong, Z. P.; Jia, F. D.; Mostamand, M.; Li, X. K.; Reich, B. B.; Teigelhöfer, A.; Yan, H.

    2017-05-01

    Multistep laser resonance ionization spectroscopy of lutetium (Lu) has been performed at TRIUMF's off-line laser ion source test stand. The even-parity Rydberg series 6 s2n d 2D3 /2 , 6 s2n d 2D5 /2 , and 6 s2n s 2S1 /2 were observed converging to the 6 s2 ionization potential. The experimental results have been compared to those of previous work. Fifty-one levels of Rydberg series 6 s2n d 2D5 /2 and 52 levels of Rydberg series 6 s2n s 2S1 /2 were reported. Additionally, six even-parity autoionization (AI) series converging to Lu ionic states 5 d 6 s 3D1 and 5 d 6 s 3D2 were observed. The level energies of these AI states were measured. The configurations of the AI states were assigned by relativistic multichannel theory within the framework of multichannel quantum defect theory.

  17. Lutetium speciation and toxicity in a microbial bioassay: testing the free-ion model for lanthanides.

    PubMed

    Weltje, Lennart; Verhoof, Lars R C W; Verweij, Wilko; Hamers, Timo

    2004-12-15

    The validity of the free-ion model (FIM) for the element lutetium (Lu), a member of the lanthanides, was assessed in experiments with the bacterium Vibrio fischeri. The FIM is mainly based on divalent metals and synthetic ligands and has not yet been validated for the trivalent lanthanides. The bioluminescence response of V. fischeri was studied at different Lu concentrations in the presence and absence of natural and synthetic organic ligands [citrate, malate, oxalate, acetate, ethylenediaminetetraacetate (EDTA), and nitrilotriacetate (NTA)]. All ligands were tested separately to ensure that their concentrations would not cause adverse effects themselves. Free Lu3+ concentrations were calculated with a speciation program, after extension of its database with the relevant Lu equilibria. The results confirmed the FIM for Lu: that is, in contrast to total dissolved Lu concentrations, free Lu3+ concentrations had an apparent relationship with the response of V. fischeri. However, a contribution of minor inorganic Lu complexes cannot be ruled out. In the presence of malate and oxalate, the EC50 for Lu3+ decreased faster in time than for the other ligands, indicating lower elimination rates. With an EC50 of 1.57 microM, Lu3+ is more toxic than La3+, Cd2+, or Zn2+ and approximately equally as toxic as Cu2+. Although the pH increased slightly during the experiments, it was shown that the influence of pH on Lu speciation was limited.

  18. Lutetium 177-DOTA-TATE therapy for esthesioneuroblastoma: A case report.

    PubMed

    Sabongi, Juliano Guerra; Gonçalves, Mônica Carboni Pereira; Alves, Cira Danielle Casado; Alves, João; Scapulatempo-Neto, Cristovam; Moriguchi, Sonia Marta

    2016-11-01

    Esthesioneuroblastoma (ENB), also known as olfactory neuroblastoma, is a rare malignant tumor that accounts for 3% of all tumors of the nasal cavity. The incidence of ENB is 0.4 cases per million in the general population, and the most common symptoms are nasal obstruction and epistaxis. Previous studies have indicated the presence of somatostatin receptors in this tumor type. Common treatment strategies for ENB include resection and adjuvant radiotherapy and/or chemotherapy (combined treatment); however, the rate of recurrence is high. Treatment of neuroendocrine tumors using radionuclides bound to somatostatin analogues is well established in clinical practice. However, a standard and effective therapeutic approach has not been reported for ENB. The current study described the case of a 74-year-old female with numerous recurrences of ENB following multiple treatments and without possibility of resection. The patient was treated with the radiolabeled-somatostatin analogue, (177)Lutetium-DOTA-octreotate ((177)Lu-DOTA-TATE), which successfully controlled the disease. This suggests that (177)Lu-DOTA-TATE is a potential treatment for ENB and may represent an effective alternative and novel therapeutic strategy for this disease.

  19. Volatile organic compounds sensing properties of tetrakis(alkylthio)-substituted lutetium(III) bisphthalocyanines thin films.

    PubMed

    Kilinç, Necmettin; Atilla, Devrim; Gürek, Ayşe Gül; Oztürk, Zafer Ziya; Ahsen, Vefa

    2009-11-15

    The effect of volatile organic compounds (VOCs) such as acetone, methanol, ethanol, chloroform, carbon tetrachloride, dichloromethane, and hexane on electrical conductivity of thin films of bis[tetrakis(alkylthio)phthalocyaninato]lutetium(III) double decker complexes [(C(n)H(2n+1)S)(4)Pc](2)Lu(III) was investigated. The [(C(n)H(2n+1)S)(4)Pc](2)Lu(III) molecules substituted with different alkylthia chains (n=6, 8, 10, 12, and 16) were coated on interdigital transducers using a jet spray technique. A change (increase or decrease) in the conductivity of the [(C(n)H(2n+1)S)(4)Pc](2)Lu(III) films was observed depending on the concentration of the VOCs, which was ranging from 500 to 5000 ppm. The decrease in the conductivity of the sensors for the dissolvent of the compounds (chloroform, carbon tetrachloride, dichloromethane and hexane) could be related to swelling of the films. On the other hand, the increase in the conductivity of the sensors for the other VOCs (acetone, methanol and ethanol) could be resulted from that the VOCs act as electron donors and/or acceptors in the films. A linear relationship between the sensor response and concentration of the VOC vapors is obtained. The sensitivities of the [(C(n)H(2n+1)S)(4)Pc](2)Lu(III) films were in the range of 2.10(-4)-3.10(-3)%/ppm.

  20. Novel borothermal process for the synthesis of nanocrystalline oxides and borides of niobium.

    PubMed

    Jha, Menaka; Ramanujachary, Kandalam V; Lofland, Samuel E; Gupta, Govind; Ganguli, Ashok K

    2011-08-21

    A new process has been developed for the synthesis of nanocrystalline niobium oxide and niobium diboride using an amorphous niobium precursor obtained via the solvothermal route. On varying the ratio of niobium precursor to boron and the reaction conditions, pure phases of nanostructured niobium oxides (Nb(2)O(5), NbO(2)), niobium diboride (NbB(2)) and core-shell nanostructures of NbB(2)@Nb(2)O(5) could be obtained at normal pressure and low temperature of 1300 °C compared to a temperature of 1650 °C normally used. The above borothermal process involves the in situ generation of B(2)O(2) to yield either oxide or diboride. The niobium oxides and borides have been characterized in detail by XRD, HRTEM and EDX studies. The core-shell structure has been investigated by XPS depth profiling, EFTEM and EELS (especially to characterize the presence of boron and the shell thickness). The niobium diboride nanorods (with high aspect ratio) show a superconducting transition with the T(c) of 6.4 K. In the core-shell of NbB(2)@Nb(2)O(5), the superconductivity of NbB(2) is masked by the niobium oxide shell and hence no superconductivity was observed. The above methodology has the benefits of realizing both oxides and borides of niobium in nanocrystalline form, in high purity and at much lower temperatures.

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    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.

  2. Phase stability and elastic properties of chromium borides with various stoichiometries.

    PubMed

    Wang, Bing; Wang, De Yu; Cheng, Zhenxiang; Wang, Xiaolin; Wang, Yuan Xu

    2013-04-15

    Phase stability is important to the application of materials. By first-principles calculations, we establish the phase stability of chromium borides with various stoichiometries. Moreover, the phases of CrB3 and CrB4 have been predicted by using a newly developed particle swarm optimization (PSO) algorithm. Formation enthalpy-pressure diagrams reveal that the MoB-type structure is more energetically favorable than the TiI-type structure for CrB. For CrB2, the WB2-type structure is preferred at zero pressure. The predicted new phase of CrB3 belongs to the hexagonal P-6m2 space group and it transforms into an orthorhombic phase as the pressure exceeds 93 GPa. The predicted CrB4 (space group: Pnnm) phase is more energetically favorable than the previously proposed Immm structure. The mechanical and thermodynamic stabilities of predicted CrB3 and CrB4 are verified by the calculated elastic constants and formation enthalpies. The full phonon dispersion calculations confirm the dynamic stability of WB2 -type CrB2 and predicted CrB3. The large shear moduli, large Young's moduli, low Poisson ratios, and low bulk and shear modulus ratios of CrB4-PSC and CrB4-PSD indicate that they are potential hard materials. Analyses of Debye temperature, electronic localization function, and electronic structure provide further understanding of the chemical and physical properties of these borides.

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

    PubMed Central

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

    2016-01-01

    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. PMID:27503412

  4. Phase Evolution in Boride-Based Cermets and Reaction Bonding onto Plain Low Carbon Steel Substrate

    NASA Astrophysics Data System (ADS)

    Palanisamy, B.; Upadhyaya, A.

    2012-04-01

    Reaction sinter bonding is a process that aims to bond two materials for improvement in properties through reactive sintering technique. The process has been effectively used to sinter hard materials like borides in situ which not only possess excellent oxidation resistance, good corrosion resistance but also resistant to abrasive wear. Sinter bonding is a unique surface modification process achieved through powder metallurgy and is competent with other techniques like boronizing sintering and sinter-brazing since it eliminates the additional operations of heat treatment and assembly and removes the inherent setbacks with these processes. This study focuses on identifying the phase evolution mechanism using characterization tools like x-ray diffractometry and energy dispersive spectroscopy and study of sinter bonding of the boron containing precursors (Mo-Cr-Fe-Ni-FeB-MoB) onto plain carbon steel. A microstructure containing Fe-based matrix dispersed with complex borides develops with temperature in the tape cast sheets. A fivefold increase in hardness between plain carbon steel in wrought condition and sinter bonded steel was observed. The multilayer consisted of a reaction zone adjacent to the interface and was investigated with the composition profile and hardness measurements. A model of sinter bonding between the cermet and the steel has also been proposed.

  5. Formation and Characterization of Hydrogen Boride Sheets Derived from MgB2 by Cation Exchange.

    PubMed

    Nishino, Hiroaki; Fujita, Takeshi; Cuong, Nguyen Thanh; Tominaka, Satoshi; Miyauchi, Masahiro; Iimura, Soshi; Hirata, Akihiko; Umezawa, Naoto; Okada, Susumu; Nishibori, Eiji; Fujino, Asahi; Fujimori, Tomohiro; Ito, Shin-Ichi; Nakamura, Junji; Hosono, Hideo; Kondo, Takahiro

    2017-10-04

    Two-dimensional (2D) materials are promising for applications in a wide range of fields because of their unique properties. Hydrogen boride sheets, a new 2D material recently predicted from theory, exhibit intriguing electronic and mechanical properties as well as hydrogen storage capacity. Here, we report the experimental realization of 2D hydrogen boride sheets with an empirical formula of H1B1, produced by exfoliation and complete ion-exchange between protons and magnesium cations in magnesium diboride (MgB2) with an average yield of 42.3% at room temperature. The sheets feature an sp(2)-bonded boron planar structure without any long-range order. A hexagonal boron network with bridge hydrogens is suggested as the possible local structure, where the absence of long-range order was ascribed to the presence of three different anisotropic domains originating from the 2-fold symmetry of the hydrogen positions against the 6-fold symmetry of the boron networks, based on X-ray diffraction, X-ray atomic pair distribution functions, electron diffraction, transmission electron microscopy, photo absorption, core-level binding energy data, infrared absorption, electron energy loss spectroscopy, and density functional theory calculations. The established cation-exchange method for metal diboride opens new avenues for the mass production of several types of boron-based 2D materials by countercation selection and functionalization.

  6. A diffusion model for describing the bilayer growth (FeB/Fe 2B) during the iron powder-pack boriding

    NASA Astrophysics Data System (ADS)

    Keddam, M.; Chentouf, S. M.

    2005-10-01

    In this paper, a diffusion model is proposed for studying the bilayer growth kinetics (FeB/Fe 2B) on pure iron substrate during the powder-pack boriding in the temperature range of 1023-1273 K. This model based on Fick's laws was solved, under certain assumptions, considering a parabolic growth of iron borides. For this purpose, a computer simulation program was created for predicting the boride layer thickness as a function of process parameters (temperature, time and surface boron content). A fairly good agreement was observed between the simulation calculations and experimental data derived from the literature.

  7. Simulation of the growth kinetics of the (FeB/Fe 2B) bilayer obtained on a borided stainless steel

    NASA Astrophysics Data System (ADS)

    Keddam, M.

    2011-01-01

    The present work is an attempt to simulate the growth kinetics of the (FeB/Fe 2B) bilayer grown on a substrate made of AISI 316 stainless steel by the application of the powder-pack boriding process, and using four different temperatures (1123, 1173, 1223 and 1273 K) and five exposure times (2, 4, 6, 8 and 10 h). The adopted diffusion model solves the mass balance equation at each growth front: (FeB/Fe 2B or FeB/substrate) under certain assumptions and without considering the diffusion zone. To consider the effect of the incubation times for the borides formation, the temperature-dependent function ϕ( T) was incorporated in the model. To validate this model, a computer code written in Matlab (version 6.5), was developed with the purpose of simulating the kinetics of the boride layers. This computer code uses the following parameters as input data: (the boriding temperature, the treatment time, the upper and lower limits of boron concentration in each iron boride, the diffusion coefficients of boron in the FeB and Fe 2B phases as well as the ϕ( T) parameter). The outputs of the computer code are the parabolic growth constant at each growth front and the thicknesses of the FeB and Fe 2B layers. A good agreement was obtained between the experimental parabolic growth constants taken from a reference work [I. Campos-Silva et al., Formation and kinetics of FeB/Fe 2B layers and diffusion zone at the surface of AISI 316 borided steels, Surf. Coat Technol., 205 (2010) 403-412] and the simulated values of the parabolic growth constants ( kFeB and k1). The present model was also able to predict the thicknesses of the FeB and Fe 2B layers at a temperature of 1243 K during 3 and 5 h. In addition, the mass gain at the material surface was also estimated as a function of the time and the upper boron content in each iron boride phase. It was shown that the simulated values of the generated mass gain are very sensitive to the increase of both temperature and the upper boron

  8. Motexafin lutetium-photodynamic therapy of prostate cancer: Short and long term effects on PSA

    PubMed Central

    Patel, Hiral; Mick, Rosemarie; Finlay, Jarod; Zhu, Timothy C.; Rickter, Elizabeth; Cengel, Keith A.; Malkowicz, S. Bruce; Hahn, Stephen M.; Busch, Theresa M.

    2009-01-01

    Purpose: The time course of serum PSA response to photodynamic therapy (PDT) of prostate cancer was measured. Experimental Design: Seventeen patients were treated in a Phase I trial of motexafin lutetium-PDT. PDT dose was calculated in each patient as the product of the ex vivo-measured pre-PDT photosensitizer level and the in situ-measured light dose. Serum PSA level was measured within two months prior to PDT (baseline), and at day 1; weeks 1-3; months 1, 2 and 3; months 4-6 and months 7-11 after PDT. Results: At 24h after PDT, serum PSA increased by 98±36% (mean ± SE) relative to baseline levels (p=0.007). When patients were dichotomized based on median PDT dose, those who received high PDT dose demonstrated a 119±52% increase in PSA compared to a 54±27% increase in patients treated at low PDT dose. Patients treated with high vs. low PDT dose demonstrated a median biochemical delay of 82 vs. 43 days (p=0.024), with biochemical delay defined as the length of time between PDT and a nonreversible increase in PSA to a value ≥baseline. Conclusions: Results show PDT to induce large, transient increases in serum PSA levels. Patients who experienced high PDT dose demonstrated greater short-term increase in PSA and a significantly more durable PSA response (biochemical delay). These data strongly promote the need for individualized delivery of PDT dose and assessment of treatment effect in PDT of prostate cancer. Information gained from such patient-specific measurements could facilitate the introduction of multiple PDT sessions in patients who would benefit. PMID:18676760

  9. Lutetium(III)-dependent self-assembly study of ciliate Euplotes octocarinatus centrin.

    PubMed

    Duan, Lian; Zhao, Ya-Qin; Wang, Zhi-Jun; Li, Guo-Ting; Liang, Ai-Hua; Yang, Bin-Sheng

    2008-02-01

    Ciliate Euplotes octocarinatus centrin (EoCen) is a member of the EF-hand superfamily of calcium-binding proteins, which often associated with the centrosomes and basal bodies. To explore the possible structural role of EoCen, we initiated a physicochemical study of the self-assembly properties of the purified protein in vitro. The native PAGE results indicate that only the integral protein shows multimers in the presence of Lu(3+). The dependence of Lu(3+) induced self-assembly of EoCen on various chemical and physical factors, including temperature, protein concentration, ionic strength and pH, was characterized using resonance light scattering (RLS). Control experiments with different metal ions suggest that Ca(2+) and Lu(3+) bindings to the N-terminal domain of EoCen are all positive to the self-assembly of the protein, and Lu(3+) exhibits the stronger effect, however, Mg(2+) alone cannot take the same effect. The experiments of 2-ptoluidinylnaphthalene-6-sulfonate (TNS) binding and ionic strength demonstrate that the lutetium(III)-dependent self-assembly is closely related to the exposure of hydrophobic cavity. Control experiment on pH value with EoCen and the fragments of it, N-terminal domain of EoCen (N-EoCen), indicates that the electrostatic effect is of small tendency to be served as the main driving force in the self-assembly of EoCen. The specific oligomerization form of the protein was exhibited by cross-linking experiment.

  10. Structural and electrochemical properties of lutetium bis-octachloro-phthalocyaninate nanostructured films. Application as voltammetric sensors.

    PubMed

    Alessio, P; Apetrei, C; Rubira, R J G; Constantino, C J L; Medina-Plazal, C; De Saja, J A; Rodríguez-Méndez, M L

    2014-09-01

    Thin films of the bis[2,3,9,10,16,17,23,24-octachlorophthalocyaninate] lutetium(III) complex (LuPc2Cl32) have been prepared by the Langmuir-Blodgett and the Langmuir-Schaefer (LS) techniques. The influence of the chlorine substituents in the structure of the films and in their spectroscopic, electrochemical and sensing properties has been evaluated. The π-A isotherms exhibit a monolayer stability greater than the observed in the unsubstituted analogue (LuPc2), being easily transferred to solid substrates, also in contrast to LuPc2. The LB and LS films present a linear growth forming stratified layers, monitored by UV-VIS absorption spectroscopy. The latter also revealed the presence of LuPc2Cl32 in the form of monomers and aggregates in both films. The FTIR data showed that the LuPc2Cl32 molecules present a non-preferential arrangement in both films. Monolayers of LB and LS were deposited onto 6 nm Ag island films to record surface-enhanced resonance Raman scattering (SERRS), leading to enhancement factors close to 2 x 10(3). Finally, LB and LS films deposited onto ITO glass have been successfully used as voltammetric sensors for the detection of catechol. The improved electroactivity of the LB and LS films has been confirmed by the reduction of the overpotential of the oxidation of catechol. The enhancement of the electrocatalytic effect observed in LB and LS films is the result of the nanostructured arrangement of the surface which increases the number of active sites. The sensors show a limit of detection in the range of 10(-5) mol/L.

  11. Early efficacy of and toxicity from lutetium-177-DOTATATE treatment in patients with progressive metastatic NET.

    PubMed

    Pencharz, Deborah; Walker, Martin; Yalchin, Mehmet; Quigley, Ann-Marie; Caplin, Martyn; Toumpanakis, Christos; Navalkissoor, Shaunak

    2017-07-01

    Lutetium-177 DOTA-D-Phe1-Tyr3-octreotide (Lu-DOTATATE) is a treatment option for patients with well-differentiated metastatic neuroendocrine tumours. Our centre started administering this therapy in 2012. The aim of this study was therefore to analyse the first cohort of patients treated with Lu-DOTATATE to determine its early efficacy and toxicity. We retrospectively analysed patient, tumour and treatment characteristics, end-of-treatment outcome, time to progression and toxicity in 79 consecutive patients treated with Lu-DOTATATE who had progressive NET according to Response Evaluation Criteria in Solid Tumours criteria. Follow-up time was 12-40 months. Study of Kaplan-Meier plots, analysis of time to progression and multiple regression analysis of factors predictive of time to progression were performed. At end-of-treatment radiological restaging, 13% of patients were found to have partial response and 64% to have stable disease; 23% of patients progressed through treatment. Overall, 47% of patients demonstrated a reduction in chromogranin A levels. The overall estimated median time to progression from the start of treatment was 28 months for the entire cohort and 31, 30 and 5 months for those with partial response, stable disease and progressive disease, respectively. On multivariate regression analysis, higher grade of tumour was found to be significantly associated with shorter progression-free survival. Three patients experienced grade 1 haematotoxicity, five grade 1 nephrotoxicity and one grade 2 nephrotoxicity. Early outcomes of patients treated with Lu-DOTATATE are similar to those in previously published series in terms of end-of-treatment efficacy and toxicity. This provides further evidence that this is a safe and efficacious form of treatment for patients with progressive metastatic neuroendocrine tumours.

  12. Investigation of high pressure phase transition and electronic properties of Lutetium Nitride

    NASA Astrophysics Data System (ADS)

    Singh, Sanjay Kumar; Verma, U. P.

    2015-09-01

    In the present manuscript we have investigated the structural, electronic and phase transition properties of the heaviest lanthanide lutetium nitride (LuN) compound using an ab initio calculations based on the density functional theory with Perdrew, Burke and Ernzerhof generalized gradient approximation (PBE-GGA) and Engel-Vosko(EV)-GGA as implemented in WIEN2k code. The basic ground state properties viz., lattice constants (a), bulk modulus (B0) and its pressure derivative (B0’) and total energy (E0) are calculated. The calculated values of lattice constant is 4.76 Å which is in good agreement with experimental value a= 4.76 A and other theoretical value. The relative stabilities of LuN at high pressures in the NaCl (B1), CsCl (B2), zinc blende (B3) and body centred tetragonal (BCT) structures are analysed. At compressed volumes, this compound is found to favour the CsCl phase rather the body centred tetragonal phase and zinc blende as observed in other lanthanum pnictides, which has been predicted by the total energy minimization. Under compression LuN undergoes a transition from NaCl to CsCl type structure at around 250.81 GPa with a volume collapse of 3.75%. To see the effect of functional we have also computed the band structure in B1 and B2 structure. Obtained result on band structure shows that LuN are semimetal by GGA while depicts semiconducting behaviour by EV-GGA. It shows metallic nature in B2 phase.

  13. Parameters for the RM1 Quantum Chemical Calculation of Complexes of the Trications of Thulium, Ytterbium and Lutetium

    PubMed Central

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

    2016-01-01

    The RM1 quantum chemical model for the calculation of complexes of Tm(III), Yb(III) and Lu(III) is advanced. Subsequently, we tested the models by fully optimizing the geometries of 126 complexes. We then compared the optimized structures with known crystallographic ones from the Cambridge Structural Database. Results indicate that, for thulium complexes, the accuracy in terms of the distances between the lanthanide ion and its directly coordinated atoms is about 2%. Corresponding results for ytterbium and lutetium are both 3%, levels of accuracy useful for the design of lanthanide complexes, targeting their countless applications. PMID:27223475

  14. Parameters for the RM1 Quantum Chemical Calculation of Complexes of the Trications of Thulium, Ytterbium and Lutetium.

    PubMed

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

    2016-01-01

    The RM1 quantum chemical model for the calculation of complexes of Tm(III), Yb(III) and Lu(III) is advanced. Subsequently, we tested the models by fully optimizing the geometries of 126 complexes. We then compared the optimized structures with known crystallographic ones from the Cambridge Structural Database. Results indicate that, for thulium complexes, the accuracy in terms of the distances between the lanthanide ion and its directly coordinated atoms is about 2%. Corresponding results for ytterbium and lutetium are both 3%, levels of accuracy useful for the design of lanthanide complexes, targeting their countless applications.

  15. 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.

  16. Titanium boride equation of state determined by in-situ X-ray diffraction.

    PubMed

    Ono, Shigeaki; Kikegawa, Takumi

    2016-12-01

    The equation of state (EOS) of titanium boride, TiB2, was investigated by in situ X-ray diffraction in a diamond anvil cell and multianvil high-pressure apparatus. The pressure-volume-temperature (P-V-T) data were collected at up to 111 GPa and room temperature for the diamond-anvil cell experiments and at up to 15 GPa and 1300 K for the multianvil experiments. No phase transition was observed through the entire range of experimental conditions. The pressure-volume data at room temperature were fitted using a Vinet EOS to obtain the isothermal bulk modulus, BT0 = 256.7 GPa, and its pressure derivative, B' T0 = 3.83. When fitting a thermal EOS using the P-V-T data for the multianvil experiments, we find that [Formula: see text] = 0.095 (GPa/K) and α 0 = 2.49 × 10(-5) K(-1).

  17. Accelerated kinetics and mechanism of growth of boride layers on titanium under isothermal and cyclic diffusion

    NASA Astrophysics Data System (ADS)

    Sarma, Biplab

    2011-12-01

    The tendency of titanium (Ti) and its alloys to wear, gall and seize during high contact stresses between sliding surfaces severely limits their applications in bearings, gears etc. One way to mitigate these problems is to modify their surfaces by applying hard and wear resistant surface coatings. Boriding, which involves solid state diffusion of boron (B) into Ti, thereby forming hard surface layers consisting of TiB2 and TiB compounds has been shown to produce extremely high wear resistant surfaces in Ti and its alloys. The growth kinetics of these layers are, however, limited by the low diffusivities of B in the high melting TiB2 and TiB compounds. On the basis of the fact that HCP metals such as Ti show enhanced (anomalous) self-diffusion near the phase transition temperature, the first hypothesis of this work has been that the diffusivity enhancement should cause rapid ingress of B atoms, thereby accelerating the growth of the hard boride layers. Isothermal boriding experiments were performed close to phase transition temperature (890, 910, and 915°C) for time periods ranging from 3 to 24 hours. It was found that indeed a much deeper growth of TiB into the Ti substrate (˜75 mum) occurred at temperatures very close to the transition temperature (910°C), compared to that obtained at 1050°C. A diffusion model based on error-function solutions of Fick's second law was developed to quantitatively illustrate the combined effects of the normal B diffusion in the TiB phase and the anomalous B diffusion in Ti phase in accelerating TiB layer growth. Furthermore, isothermal boriding experiments close to transition temperature (900°C) for a period of 71 hours resulted in coating thickness well above 100 mum, while at 1050°C, the layer growth saturated after about 24 hours of treatment time. In the second part of this work, a novel approach named "cyclic-phase-changediffusion, (CPCD)," to create deeper TiB2 and TiB coating layers on CP-Ti by cyclic thermal processing

  18. New YMo{sub 3}B{sub 7} boride and its structure

    SciTech Connect

    Mikhalenko, S.I.; Kuz`ma, Yu.B.; Babizhetskii, V.S.

    1995-05-01

    The crystal structure of YMo{sub 3}B{sub 7} boride is determined (a CAD-4 diffractometer, MoK{sub {alpha}} radiation, R = 0.019 for 668 reflections). The crystals are orthorhombic: a = 11.012(1) {Angstrom}, b = 3.1013(3) {Angstrom}, c = 12.864(1) {Angstrom}; Z = 4; {rho}{sub calc} = 6.839(2) g/cm{sup 3}; and sp. gr. Pnma. The structure belongs to a new type: metal atoms form trigonal prisms, within which boron atoms occur. Four columns of alternating empty orthorhombic [EMo{sub 4}Y] pyramids and [EMo{sub 2}Y{sub 2}] tetrahedra run in the b direction. The boron atoms form ribbons of six-membered rings. The ribbons are tilted to the ab plane. 8 refs., 3 figs.

  19. The microstructure and superplastic behavior of clean mechanically alloyed titanium - titanium boride alloys

    SciTech Connect

    Brown, A.P.; Brydson, R.; Hammond, C.; Wisbey, A.; Godfrey, T.M.T.

    2000-07-01

    The superplastic forming (SPF) of titanium alloys is an established technology. A reduction in grain size from that of the typical sheet materials would lead to enhanced SPF properties and hence a reduction in production cycle times. This study describes the microstructural development and superplastic behavior of fine-grained Ti-6%Al-4%V alloys. Ball-milling Ti-6%Al-4%V powder produces a nanocrystalline material; however on consolidation by hot isostatic pressing rapid grain growth occurs. Addition of boron powder during milling leads to boride precipitates in the matrix of the consolidated alloy. The precipitates are dispersed inhomogeneously, resulting in localized grain refinement. Superplastic testing revealed cavitation formation but in comparison to conventional sheet material, large elongations were achieved at relatively high strain rates.

  20. Superconductivity in the Metal Rich Li-Pd-B Ternary Boride

    NASA Astrophysics Data System (ADS)

    Togano, K.; Badica, P.; Nakamori, Y.; Orimo, S.; Takeya, H.; Hirata, K.

    2004-12-01

    Superconductivity at about 8K was observed in the metal-rich Li-Pd-B ternary system. Structural, microstructural, electrical, and magnetic investigations for various compositions proved that the Li2Pd3B compound, which has an antiperovskite cubic structure composed of distorted Pd6B octahedrons, is responsible for the superconductivity. This is the first observation of superconductivity in metal-rich ternary borides containing alkaline metal and Pd as a late transition metal. The compound prepared by arc melting has a high density and is relatively stable in the air. The upper critical fields Hc2(0) estimated by linear extrapolation and the Werthamer-Helfand-Hohenberg theory are 6.2 and 4.8T, respectively.

  1. 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

  2. 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

  3. Piano-stool lutetium amido and imido compounds supported by a constrained bis(oxazoline)cyclopentadienyl ligand

    DOE PAGES

    Lampland, Nicole L.; Zhu, Jing; Hovey, Megan; ...

    2015-06-25

    {BoMCptet}Lu(CH2Ph)2 (1; BoMCptet = MeC(OxMe2 2C5Me4; OxMe2 = 4,4-dimethyl-2-oxazoline) was prepared in 95% yield from the reaction of BoMCptetH and Lu(CH2Ph)3THF3. Compound 1 reacts with 1 or 2 equiv of H2NCH2R (R = C6H5, 1-C10H7) to give the corresponding imido complexes [{BoMCptet}LuNCH2R]2 (R = C6H5 (2a), 1-C10H7 (2b)) or amido complexes {BoMCptet}Lu(NHCH2R)2 (R = C6H5 (3a), 1-C10H7 (3b)). When isolated, the imido species are insoluble in nonprotic organic solvents. Crystallographic characterization reveals dimeric [{BoMCptet}LuNCH2(1-C10H7)]2 in the solid state. The reaction of 1 and NH3B(C6F5)3 affords crystallographically characterized {BoMCptet}Lu{NHB(C6F5)2}C6F5. This species is proposed to form via a transient lutetium imido, whichmore » undergoes C6F5 migration to the lutetium center.« less

  4. ABAB homoleptic bis(phthalocyaninato)lutetium(III) complex: toward the real octupolar cube and giant quadratic hyperpolarizability.

    PubMed

    Ayhan, Mehmet Menaf; Singh, Anu; Hirel, Catherine; Gürek, Ayşe Gül; Ahsen, Vefa; Jeanneau, Erwann; Ledoux-Rak, Isabelle; Zyss, Joseph; Andraud, Chantal; Bretonnière, Yann

    2012-02-29

    The concept of octupolar molecules has considerably enlarged the engineering of second-order nonlinear optical materials by giving access to 2D and 3D architectures. However, if the archetype of octupolar symmetry is a cube with alternating donor and acceptor groups at the corners, no translation of this ideal structure into a real molecule has been realized to date. This may be achieved by designing a bis(phthalocyaninato)lutetium(III) double-decker complex with a crosswise ABAB phthalocyanine bearing alternating electron-donor and electron-acceptor groups. In this communication, we present the first step toward this goal with the synthesis, crystal structure determination, and measurement of the molecular first-order hyperpolarizability β by harmonic light diffusion, of an original lutetium(III) sandwich complex displaying the required ABAB-type alternation for one face of the cube. This structure is characterized by an intense absorption in the near-IR due to an intervalence transition and exhibits the highest quadratic hyperpolarizability ever reported for an octupolar molecule, √<β(2)(HLS)> = 5750 × 10(-30) esu.

  5. Anti-biofouling polymer-decorated lutetium-based nanoparticulate contrast agents for in vivo high-resolution trimodal imaging.

    PubMed

    Liu, Zhen; Dong, Kai; Liu, Jianhua; Han, Xueli; Ren, Jinsong; Qu, Xiaogang

    2014-06-25

    Nanomaterials have gained considerable attention and interest in the development of novel and high-resolution contrast agents for medical diagnosis and prognosis in clinic. A classical urea-based homogeneous precipitation route that combines the merits of in situ thermal decomposition and surface modification is introduced to construct polyethylene glycol molecule (PEG)-decorated hybrid lutetium oxide nanoparticles (PEG-UCNPs). By utilizing the admirable optical and magnetic properties of the yielded PEG-UCNPs, in vivo up-conversion luminescence and T1 -enhanced magnetic resonance imaging of small animals are conducted, revealing obvious signals after subcutaneous and intravenous injection, respectively. Due to the strong X-ray absorption and high atomic number of lanthanide elements, X-ray computed-tomography imaging based on PEG-UCNPs is then designed and carried out, achieving excellent imaging outcome in animal experiments. This is the first example of the usage of hybrid lutetium oxide nanoparticles as effective nanoprobes. Furthermore, biodistribution, clearance route, as well as long-term toxicity are investigated in detail after intravenous injection in a murine model, indicating the overall safety of PEG-UCNPs. Compared with previous lanthanide fluorides, our nanoprobes exhibit more advantages, such as facile construction process and nearly total excretion from the animal body within a month. Taken together, these results promise the use of PEG-UCNPs as a safe and efficient nanoparticulate contrast agent for potential application in multimodal imaging. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. High-phasing-power lanthanide derivatives: taking advantage of ytterbium and lutetium for optimized anomalous diffraction experiments using synchrotron radiation.

    PubMed

    Girard, E; Anelli, P L; Vicat, J; Kahn, R

    2003-10-01

    Ytterbium and lutetium are well suited for optimized anomalous diffraction experiments using synchrotron radiation. Therefore, two lanthanide complexes Yb-HPDO3A and Lu-HPDO3A have been produced that are similar to the Gd-HPDO3A complex already known to give good derivative crystals. Derivative crystals of hen egg-white lysozyme were obtained by co-crystallization using 100 mM solutions of each lanthanide complex. De novo phasing has been carried out using single-wavelength anomalous diffraction on data sets collected on each derivative crystal at the L(III) absorption edge of the corresponding lanthanide (ff" = 28 e(-)). A third data set was collected on a Lu-HPDO3A derivative crystal at the Se K absorption edge with f"(Lu) = 10 e(-). The structures were refined and compared with the known structure of the Gd-HPDO3A lysozyme derivative. The quality of the experimental electron-density maps allows easy model building. With L(III) absorption edges at shorter wavelengths than the gadolinium absorption edge, lutetium and ytterbium, when chelated by a ligand such as HPDO3A, form lanthanide complexes that are especially interesting for synchrotron-radiation experiments in structural biology.

  7. Piano-Stool Lutetium Amido and Imido Compounds Supported by a Constrained Bis(oxazoline)cyclopentadienyl Ligand.

    PubMed

    Lampland, Nicole L; Zhu, Jing; Hovey, Megan; Jana, Barun; Ellern, Arkady; Sadow, Aaron D

    2015-07-20

    {Bo(M)Cp(tet)}Lu(CH2Ph)2 (1; Bo(M)Cp(tet) = MeC(Ox(Me2))2C5Me4; Ox(Me2) = 4,4-dimethyl-2-oxazoline) was prepared in 95% yield from the reaction of Bo(M)Cp(tet)H and Lu(CH2Ph)3THF3. Compound 1 reacts with 1 or 2 equiv of H2NCH2R (R = C6H5, 1-C10H7) to give the corresponding imido complexes [{Bo(M)Cp(tet)}LuNCH2R]2 (R = C6H5 (2a), 1-C10H7 (2b)) or amido complexes {Bo(M)Cp(tet)}Lu(NHCH2R)2 (R = C6H5 (3a), 1-C10H7 (3b)). Once isolated, the imido species are insoluble in nonprotic organic solvents. Crystallographic characterization reveals dimeric [{Bo(M)Cp(tet)}LuNCH2(1-C10H7)]2 in the solid state. The reaction of 1 and NH3B(C6F5)3 affords crystallographically characterized {Bo(M)Cp(tet)}Lu{NHB(C6F5)2}C6F5. This species is proposed to form via a transient lutetium imido, which undergoes C6F5 migration to the lutetium center.

  8. 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

  9. Corrosion Resistance of Nanopowders of Borides and Carbides of IV-VIB Group Metals in the Nickeling Electrolytes

    NASA Astrophysics Data System (ADS)

    Shakhnin, Dmytro; Malyshev, Viktor; Kuschevskaya, Nina; Gab, Angelina

    2017-07-01

    The corrosion resistance of nanopowders of borides and carbides of metals of IV-VIB groups, as well as of silicon carbide, was studied in the standard nickeling electrolytes. As objects of study, nanopowders with the content of the main phase 91.8-97.6% and with the average particle size 32-78 nm were used. Their corrosion resistance was evaluated depending on the acidity of the electrolyte, temperature, and duration of the interaction. It was found that, by the corrosion resistance in the electrolytes solutions, nanopowders of borides and carbides within each group of compounds are similar and characterized by unlimited period of induction in alkaline media. An exception is the nanopowder of silicon carbide which is resistant to the solution of any acidity.

  10. Synthesis and characterization of nitrogen-phosphorus-based fire retardants modified by boride/propanetriol flyeidyl ether complex

    NASA Astrophysics Data System (ADS)

    Kang, Haijiao; Ma, Linrong; Zhang, Shifeng; Li, Jianzhang

    2015-07-01

    A Boride/propanetriol glyeidyl ether (B/PTGE) complex was employed to intensify the fire resistance capabilities of nitrogen-phosphorus (NP) fire retardants by reacting with phosphoric acid and urea to yield nitrogen-phosphorus-boron-PTGE fire retardants. The effects of NPB-PTGE fire retardants on wooden properties were characterized by limit oxygen index (LOI), cone calorimetry, X-ray Diffraction (XRD) and scanning electron microscopy (SEM). The results depict that the fire resistance of the B/PTGE complex modified by NP-based fire retardants was improved significantly. The PTGE was at 10% boride at 2%, and the treated wood has the LOI of 52%, which is 11.46% higher compared with woods treated with NP fire retardant.

  11. Structural and mechanical properties of transition metal borides Nb2MB2 (M=Tc, Ru, and Os) under pressure

    NASA Astrophysics Data System (ADS)

    Li, Xiaofeng; Yan, Haiyan; Wei, Qun

    2016-10-01

    First-principle total energy calculations are employed to provide a fundamental understanding of the structural, mechanical, and electronic properties of transition metal borides Nb2MB2 (M=Tc, Ru, and Os) within the tetragonal superstructure P4/mnc structure. The mechanically and dynamically stabilities of three borides have been demonstrated by the elastic constants and phonons calculations under pressure. Among these three compounds, Nb2TcB2 exhibits the biggest bulk and Young's modulus, smallest Poission's ratio, and highest harness. Density of states of them revealed that the strong B-B, Nb-B and M-B covalent bonds are major driving forces for their high bulk and shear moduli as well as small Poisson's ratio.

  12. Pre-irradiation spatial distribution and stability of boride particles in rapidly solidified boron-doped stainless steels

    SciTech Connect

    Kanani, N.; Arnberg, L.; Harling, O.K.

    1981-01-01

    The time temperature behavior of boride particles has been studied in rapidly solidified ultra low carbon and nitrogen modified 316 stainless steel with 0.088% boron and 0.45% zirconium. The results show that the as-splat-cooled specimens exhibit precipitates at the grain boundaries and triple junctions. For temperatures up to about 750/sup 0/C no significant microstructural changes occur for short heat treatment times. In the temperature range of 750 to 950/sup 0/C, however, particles typically 100 to 500 A in diameter containing Zr and B are formed within the grains. Higher temperatures enhance the formation of such particles and give rise to particle networks. The results show that a fine and uniform distribution of the boride particles almost exclusively within the grains can be achieved if proper annealing conditions are chosen. This type of distribution is an important requirement for the homogeneous production of helium during neutron irradiation in fast reactors.

  13. Lutetium oxyorthosilicate block detector readout by avalanche photodiode arrays for high resolution animal PET.

    PubMed

    Pichler, B J; Swann, B K; Rochelle, J; Nutt, R E; Cherry, S R; Siegel, S B

    2004-09-21

    Avalanche photodiodes (APDs) have proven to be useful as light detectors for high resolution positron emission tomography (PET). Their compactness makes these devices excellent candidates for replacing bulky photomultiplier tubes (PMTs) in PET systems where space limitations are an issue. The readout of densely packed, 10 x 10 lutetium oxyorthosilicate (LSO) block detectors (crystal size 2.0 x 2.0 x 12 mm3) with custom-built monolithic 3 x 3 APD arrays was investigated. The APDs had a 5 x 5 mm2 active surface and were arranged on a 6.25 mm pitch. The dead space on the edges of the array was 1.25 mm. The APDs were operated at a bias voltage of approximately 380 V for a gain of 100 and a dark current of 10 nA per APD. The standard deviation in gain between the APDs in the array ranged from 1.8 to 6.5% as the gain was varied from 50 to 108. A fast, low-noise, multi-channel charge sensitive preamplifier application-specific integrated circuit (ASIC) was developed for the APD readout. The amplifier had a rise time of 8 ns, a noise floor of 515 e- rms and a 9 e- pF(-1) noise slope. An acquired flood image showed that all 100 crystals from the block detector could be resolved. Timing measurements with single-channel LSO-APD detectors, as well as with the array, against a plastic scintillator and PMT assembly showed a time resolution of 1.2 ns and 2.5 ns, respectively. The energy resolution measured with a single 4.0 x 4.0 x 10 mm3 LSO crystal, wrapped in four-layer polytetrafluoroethylene (PTFE) tape and coupled with optical grease on a single APD of the array, yielded 15% (full width at half maximum, FWHM) at 511 keV. Stability tests over 9 months of operation showed that the APD arrays do not degrade appreciably. These results demonstrate the ability to decode densely packed LSO scintillation blocks with compact APD arrays. The good timing and energy resolution makes these detectors suitable for high resolution PET.

  14. Optimizing imaging protocols for overweight and obese patients: a lutetium orthosilicate PET/CT study.

    PubMed

    Halpern, Benjamin S; Dahlbom, Magnus; Auerbach, Martin A; Schiepers, Christiaan; Fueger, Barbara J; Weber, Wolfgang A; Silverman, Daniel H S; Ratib, Osman; Czernin, Johannes

    2005-04-01

    High photon attenuation and scatter in obese patients affect image quality. The purpose of the current study was to optimize lutetium orthosilicate (LSO) PET image acquisition protocols in patients weighing > or =91 kg (200 lb). Twenty-five consecutive patients (16 male and 9 female) weighing > or =91 kg (200 lb; range, 91-168 kg [200-370 lb]) were studied with LSO PET/CT. After intravenous injection of 7.77 MBq (0.21 mCi) of 18F-FDG per kilogram of body weight, PET emission scans were acquired for 7 min/bed position. Single-minute frames were extracted from the 7 min/bed position scans to reconstruct 1-7 min/bed position scans for each patient. Three reviewers independently analyzed all 7 reconstructed whole-body images of each patient. A consensus reading followed in cases of disagreement. Thus, 175 whole-body scans (7 per patient) were analyzed for number of hypermetabolic lesions. A region-of-interest approach was used to obtain a quantitative estimate of image quality. Fifty-nine hypermetabolic lesions identified on 7 min/bed position scans served as the reference standard. Interobserver concordance increased from 64% for 1 min/bed position scans to 70% for 3 min/bed position scans and 78% for 4 min/bed position scans. Concordance rates did not change for longer imaging durations. Region-of-interest analysis revealed that image noise decreased from 21% for 1 min/bed position scans to 14%, 13%, and 11% for, respectively, 4, 5, and 7 min/bed position scans. When compared with the reference standard, 14 lesions (24%) were missed on 1 min/bed position scans but only 2 (3%) on 4 min/bed position scans. Five minute/bed position scans were sufficient to detect all lesions identified on the 7 min/bed position scans. Lesion detectability and reader concordance peaked for 5 min/bed position scans, with no further diagnostic gain achieved by lengthening the duration of PET emission scanning. Thus, 5 min/bed position scans are sufficient for optimal lesion detection with

  15. Bis(tetrabenzotriazaporphyrinato) and (tetrabenzotriazaporphyrinato)(phthalocyaninato) lutetium(III) complexes--novel sandwich-type tetrapyrrolic ligand based NIR absorbing electrochromes.

    PubMed

    Pushkarev, Victor E; Kalashnikov, Valery V; Trashin, Stanislav A; Borisova, Nataliya E; Tomilova, Larisa G; Zefirov, Nikolay S

    2013-09-14

    The first sandwich-type complexes have been prepared for tetrabenzotriazaporphyrin ligands. The compounds reveal intrinsic UV-Vis/NIR absorption as well as peculiar electrochromic behavior. The heteroleptic (tetrabenzotriazaporphyrinato)(phthalocyaninato) lutetium derivative shows intermediate spectral and electrochemical properties with respect to homoleptic relatives.

  16. Influence of cations on the complexation yield of DOTATATE with yttrium and lutetium: a perspective study for enhancing the 90Y and 177Lu labeling conditions.

    PubMed

    Asti, Mattia; Tegoni, Matteo; Farioli, Daniela; Iori, Michele; Guidotti, Claudio; Cutler, Cathy S; Mayer, Pat; Versari, Annibale; Salvo, Diana

    2012-05-01

    The DOTA macrocyclic ligand can form stable complexes with many cations besides yttrium and lutetium. For this reason, the presence of competing cationic metals in yttrium-90 and lutetium-177 chloride solutions can dramatically influence the radiolabeling yield. The aim of this study was to evaluate the coordination yield of yttrium- and lutetium-DOTATATE complexes when the reaction is performed in the presence of varying amounts of competing cationic impurities. In the first set of experiments, the preparation of the samples was performed by using natural yttrium and lutetium (20.4 nmol). The molar ratio between DOTATATE and these metals was 1 to 1. Metal competitors (Pb(2+), Zn(2+), Cu(2+), Fe(3+), Al(3+), Ni(2+), Co(2+), Cr(3+)) were added separately to obtain samples with varying molar ratio with respect to yttrium or lutetium (0.1, 0.5, 1, 2 and 10). The final solutions were analyzed through ultra high-performance liquid chromatography with an UV detector. In the second set of experiments, an amount of (90)Y or (177)Lu chloride (6 MBq corresponding to 3.3 and 45 pmol, respectively) was added to the samples, and a radio-thin layer chromatography analysis was carried out. The coordination of Y(3+) and Lu(3+) was dramatically influenced by low levels of Zn(2+), Cu(2+) and Co(2+). Pb(2+) and Ni(2+) were also shown to be strong competitors at higher concentrations. Fe(3+) was expected to be a strong competitor, but the effect on the incorporation was only partly dependent on its concentration. Al(3+) and Cr(3+) did not compete with Y(3+) and Lu(3+) in the formation of DOTATATE complexes. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. On the use of X-ray absorption spectroscopy to elucidate the structure of lutetium adenosine mono- and triphosphate complexes.

    PubMed

    Mostapha, S; Berthon, C; Fontaine-Vive, F; Gaysinski, M; Guérin, L; Guillaumont, D; Massi, L; Monfardini, I; Solari, P L; Thomas, O P; Charbonnel, M C; Den Auwer, C

    2014-02-01

    Although the physiological impact of the actinide elements as nuclear toxicants has been widely investigated for half a century, a description of their interactions with biological molecules remains limited. It is however of primary importance to better assess the determinants of actinide speciation in cells and more generally in living organisms to unravel the molecular processes underlying actinide transport and deposition in tissues. The biological pathways of this family of elements in case of accidental contamination or chronic natural exposure (in the case of uranium rich soils for instance) are therefore a crucial issue of public health and of societal impact. Because of the high chemical affinity of those actinide elements for phosphate groups and the ubiquity of such chemical functions in biochemistry, phosphate derivatives are considered as probable targets of these cations. Among them, nucleotides and in particular adenosine mono- (AMP) and triphosphate (ATP) nucleotides occur in more chemical reactions than any other compounds on the earth's surface, except water, and are therefore critical target molecules. In the present study, we are interested in trans-plutonium actinide elements, in particular americium and curium that are more rarely considered in environmental and bioaccumulation studies than early actinides like uranium, neptunium and plutonium. A first step in this strategy is to work with chemical analogues like lanthanides that are not radioactive and therefore allow extended physical chemical characterization to be conducted that are difficult to perform with radioactive materials. We describe herein the interaction of lutetium(III) with adenosine AMP and ATP. With AMP and ATP, insoluble amorphous compounds have been obtained with molar ratios of 1:2 and 1:1, respectively. With an excess of ATP, with 1:2 molar ratio, a soluble complex has been obtained. A combination of spectroscopic techniques (IR, NMR, ESI-MS, EXAFS) together with quantum

  18. Superconductivity of various borides and the role of carbon in their high performance

    NASA Astrophysics Data System (ADS)

    Awana, V. P. S.; Vajpayee, Arpita; Mudgel, Monika; Kishan, H.

    2009-03-01

    The superconductivity of MgB2, Mg1-xAlxB2 and NbB2+x is compared. The stretched c-lattice parameter (c = 3.52 Å) of MgB2 in comparison to NbB2.8 (c = 3.32 Å) and AlB2 (c = 3.25 Å) decides empirically the population of their π and σ bands and, as a result, their Tc values at 39 and 11 K, respectively, for the first two and no superconductivity for the latter. Besides stretching of the c-lattice parameter not only the density of the carriers but also their signs change in these isostructural di-borides. The thermoelectric power of these compounds clearly demonstrates their changing π and σ band contributions and the ensuing appearance/disappearance of superconductivity. An increased c parameter increases the boron plane constructed hole type σ band population and decreases the contribution from the Mg or Al plane electron type π band. This turns the hole type (mainly σ band conduction) MgB2 superconductor (39 K) into the electron type (mainly π band conduction) non-superconducting AlB2. The importance of hole type σ band conduction dominating the superconductivity of the various borides is further established by the high performance of intrinsically pinned MgB2-xCx. Our results on MgB2 added with nano-diamond, nano-SiC and various organics such as glucose, PVA and adipic acid, when compared with MgB2-xCx, clearly demonstrate that the main role is played by C substitution at the B site in the host MgB2 and the ensuing σ plane disorder and vortex pinning. The best strategy could be to add (<10 nm) nanoparticles to MgB1.8C0.2 to ensure both extrinsic pinning by the former and intrinsic pinning by the latter.

  19. In situ chemichromic studies of interactions between a lutetium bis-octaalkyl-substituted phthalocyanine and selected biological cofactors

    PubMed Central

    Pal, C.; Cammidge, A. N.; Cook, M. J.; Sosa-Sanchez, J. L.; Sharma, A. K.; Ray, A. K.

    2012-01-01

    Spin-coated films, approximately 100 nm thick, of a newly synthesized bis[octakis(octyl)phthalocyaninato] lutetium(III) complex on ultrasonically cleaned glass substrates exhibit pronounced chemichromic behaviour with potential application in healthcare. In situ kinetic optical absorption spectroscopic measurements show that the phthalocyanine Q-band is red shifted by 60 nm upon oxidation arising from exposure to bromine vapour. Recovery to the original state is achieved by the treatment of the oxidized films with nicotinamide adenine dinucleotide and l-ascorbic acid (vitamin C) in an aqueous solution containing 1.5 M lithium perchlorate. The neutralization process is found to be governed by first-order kinetics. The linear increase of the reduction rate with increasing concentration of cofactors provides a basis for calibration of analyte concentrations ranging from 3.5 mM down to 0.03 mM. PMID:21676969

  20. Nonlinear optical properties of lutetium and dysprosium bisphthalocyanines at 1550 nm with femto- and nanosecond pulse excitation

    NASA Astrophysics Data System (ADS)

    Plekhanov, A. I.; Basova, T. V.; Parkhomenko, R. G.; Gürek, A. G.

    2017-02-01

    In this work, the nonlinear optical properties of unsubstituted lutetium (LuPc2) and dysprosium (DyPc2) bisphthalocyanines as well as octasubstituted Lu(PcR8)2 derivative with R=-S(C6H13) were studied at a wavelength of 1550 nm with 10 ns and 300 fs pulses. Based on Z-scan measurements the nonlinear absorption and refraction coefficient as well as the nature of nonlinear optical properties were analyzed for these materials. Open aperture Z-scan indicates strong two-photon absorption in all three bisphthalocyanines in nano- and femtosecond regimes. With good nonlinear optical coefficients, bisphthalocyanines of rare earth elements are expected to be promising materials for the creation of optical limiters.

  1. Raman scattering in organic semiconductors based on erbium biphthalocyanine molecules and chlorine-containing europium-lutetium triphthalocyanine molecules

    SciTech Connect

    Belogorokhov, I. A.; Mamichev, D. A.; Dronov, M. A.; Pushkarev, V. E.; Tomilova, L. G.; Khokhlov, D. R.

    2010-08-15

    The Raman spectra of semiconductor structures based on erbium biphthalocyanine molecules and chlorine-substituted europium-lutetium triphthalocyanine molecules are studied on excitation with Ar{sup +} laser radiation at the wavelength 514 nm. The data on the spectral position of Raman intensity peaks related to vibronic states of the basic molecular groups forming the semiconductor are obtained. Raman lines irrelevant to the known vibronic states of the basic phthalocyanine molecular groups are observed in the ranges 100-500 and 500-900 cm{sup -1}. It is shown that, in the spectra of triphthalocyanine, some lines are structurally complex and shifted with respect to the characteristic lines of molecular groups by several inverse centimeters.

  2. In situ chemichromic studies of interactions between a lutetium bis-octaalkyl-substituted phthalocyanine and selected biological cofactors.

    PubMed

    Pal, C; Cammidge, A N; Cook, M J; Sosa-Sanchez, J L; Sharma, A K; Ray, A K

    2012-01-07

    Spin-coated films, approximately 100 nm thick, of a newly synthesized bis[octakis(octyl)phthalocyaninato] lutetium(III) complex on ultrasonically cleaned glass substrates exhibit pronounced chemichromic behaviour with potential application in healthcare. In situ kinetic optical absorption spectroscopic measurements show that the phthalocyanine Q-band is red shifted by 60 nm upon oxidation arising from exposure to bromine vapour. Recovery to the original state is achieved by the treatment of the oxidized films with nicotinamide adenine dinucleotide and l-ascorbic acid (vitamin C) in an aqueous solution containing 1.5 M lithium perchlorate. The neutralization process is found to be governed by first-order kinetics. The linear increase of the reduction rate with increasing concentration of cofactors provides a basis for calibration of analyte concentrations ranging from 3.5 mM down to 0.03 mM.

  3. Low-damping sub-10-nm thin films of lutetium iron garnet grown by molecular-beam epitaxy

    NASA Astrophysics Data System (ADS)

    Jermain, C. L.; Paik, H.; Aradhya, S. V.; Buhrman, R. A.; Schlom, D. G.; Ralph, D. C.

    2016-11-01

    We analyze the structural and magnetic characteristics of (111)-oriented lutetium iron garnet (Lu3Fe5O12) films grown by molecular-beam epitaxy, for films as thin as 2.8 nm. Thickness-dependent measurements of the in- and out-of-plane ferromagnetic resonance allow us to quantify the effects of two-magnon scattering, along with the surface anisotropy and the saturation magnetization. We achieve effective damping coefficients of 11.1 (9 )×10-4 for 5.3 nm films and 32 (3 )×10-4 for 2.8 nm films, among the lowest values reported to date for any insulating ferrimagnetic sample of comparable thickness.

  4. A model for studying the kinetics of the formation of Fe 2B boride layers at the surface of a gray cast iron

    NASA Astrophysics Data System (ADS)

    Keddam, M.; Chegroune, R.

    2010-06-01

    The present work estimates, using a kinetic model, the growth kinetics of Fe 2B boride layers generated at the surface of a gray cast iron via the powder-pack boriding considering three different temperatures (1173, 1223 and 1273 K) and four treatment times (2, 4, 6 and 8 h). By the use of the mass balance equation at the (Fe 2B/substrate) interface under certain assumptions and considering the effect of the boride incubation time, it was possible to estimate the corresponding parabolic growth constant in terms of two parameters αCupFeB and β( T) depending on the boron content in the Fe 2B phase and on the process temperature, respectively. The mass gain at the material surface and the instantaneous velocity of the (Fe 2B/substrate) interface were also estimated. A fairly good agreement was observed between the experimental parabolic growth constants taken from a reference work (Campos-Silva et al., Characterization of boride layers formed at the surface of gray cast irons, Kovove Mater. 47 (2009) 1-7.) and the simulated values of the parabolic growth constants. Furthermore, the boride layer thicknesses were predicted and experimentally verified for three process temperatures and four treatment times.

  5. Phase stability and mechanical properties of tungsten borides from first principles calculations.

    PubMed

    Zhao, Erjun; Meng, Jian; Ma, Yanming; Wu, Zhijian

    2010-10-28

    The phase stability and mechanical properties of tungsten borides W(2)B, WB, WB(2), W(2)B(5) and WB(4) were extensively studied by first-principles calculations within density functional theory. The thermodynamic and mechanical stabilities were examined. Our calculations on the enthalpy-pressure relationship and convex hulls have demonstrated that at zero pressure, the experimentally observed W(2)B-W(2)B (W(2)B-W(2)B represents W(2)B in W(2)B structure type, the same hereinafter) and WB-WB, and assumed WB(2)-ReB(2) phases are stable against decomposition into other components. The estimated hardness of WB(2)-ReB(2) is 39.4 GPa, suggesting that it is a potentially hard compound. At 60 GPa, the most stable phases are WB-WB and WB(2)-WB(2). WB-WB, WB(2)-AlB(2) and WB(4) are the ground state phases at 100 GPa. The phase transition mechanism for WB(2) was discussed. The synthesis of WB(2)-AlB(2) could be conducted at high pressures.

  6. 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.

  7. The structural stabilities, mechanical properties and hardness of chromium tetraboride: Compared with low-B borides

    NASA Astrophysics Data System (ADS)

    Zhong, Ming-Min; Huang, Cheng; Tian, Chun-Ling

    2016-10-01

    Using the first-principles calculations, we provide a systemic understanding of the structural features and phase stability, mechanical and electronic properties, as well as the roles of boron (B) atom arrangement in the hardness for chromium borides. The structural and relative energy searches together with formation enthalpy confirm the most stable Cr2B with an orthorhombic Fddd symmetry, CrB with an orthorhombic Cmcm symmetry, CrB2 with a hexagonal P63/mmc symmetry and chromium tetraboride (CrB4) with an orthorhombic Pnnm symmetry. The shear modulus, Young’s modulus and C44 increase with the boron content, while the Poisson’s ratio and B/G ratio have an opposite tendency. Moreover, due to higher B content, strong three-dimensional (3D) covalent B networks and lower metallic contribution, CrB4 with Pnnm symmetry has the largest hardness value (46.8 GPa), exceeding the superhard limit, indicating its superhard nature.

  8. High borides: determining the features and details of lattice dynamics from neutron spectroscopy

    NASA Astrophysics Data System (ADS)

    Alekseev, P. A.

    2015-04-01

    We review wide-ranging research that combines inelastic neutron scattering spectroscopy with phenomenological and ab initio calculations to study the lattice dynamics and specifics of the electron-phonon interaction in three-dimensional boron cluster network systems M B_6 and M B12 ( M= {La}, {Sm}, and {Yb}, {Lu}, {Zr}). A close similarity is found between the atomic vibration spectra of these systems, which is fundamentally due to a strong hierarchy of interatomic interaction in these systems and which manifests itself both in the shape of the low-energy phonon dispersion and in the position of the high-energy edge of the spectrum. Manifestations of strong electron-phonon interactions in the lattice vibration spectra of borides are studied in detail and their relation to the nature and features of the valence-unstable state of rare-earth ions is examined. Resonance nonadiabaticity and magnetovibration interaction effects in spin- and valence-fluctuating systems are given special attention.

  9. Joining of zirconium boride based refractory ceramics to Ti6Al4V

    NASA Astrophysics Data System (ADS)

    Muolo, Maria Luigia; Ferrera, Elena; Morbelli, Luisa; Zanotti, Claudio; Passerone, Alberto

    2003-09-01

    The exploitation of the peculiar characteristics of ceramic refractory materials in extreme conditions (as for Thermal Protection Systems - TPS) often depends to a great extent on the ability to join different ceramics one to the other and to special metallic alloys. Joints may be achieved in a number of ways, but principally are made by either solid phase or liquid phase transformations (brazing). Brazed joints are difficult to realise in the presence of ceramic materials, due to the fact that they are not wet, in general, by liquid metals. This paper presents experimental results on the wettability characteristics of zirconium boride based materials (with Si3N4, Ni etc.) by an AgZr alloy, the microstructures and thermal tests of brazed joints with the special alloy Ti6Al4V. The wetting data will be examined in terms of interfacial characteristics and in terms of the kinetics of spreading. Thermal tests and models will be devoted to evaluate and measure the thermal insulation capacity of the ceramic layers in order to determine the optimal thickness as a function of the foreseen outer surface temperature.

  10. Preparation of iron boride-silica core-shell nanoparticles with soft ferromagnetic properties.

    PubMed

    Saiyasombat, C; Petchsang, N; Tang, I M; Hodak, J H

    2008-02-27

    A one-pot aqueous chemical synthesis for silica-passivated ferromagnetic nanoparticles is presented. The average size of these particles is 84 ± 20 nm. The x-ray and electron diffraction experiments revealed that the nanoparticles are mainly composed of polycrystalline iron boride. The broad x-ray diffraction peak leads to an average crystallite size of 1.8 nm, which is much smaller than the overall size of the particles, and is consistent with the polycrystalline nature of the samples. Mössbauer spectroscopy and magnetization experiments were used to establish the room temperature magnetic properties as well as the chemical nature of the particles. Fe(2)B dominates the composition of the nanoparticles, having a hyperfine field broadly distributed in the 10-33 T range. Alpha iron, the second ferromagnetic material identified in the particles, amounts to 4.6% of the composition. Finally, a paramagnetic phase accounting for approximately 14.6% of the material of the particles was also detected. These nanoparticles contain a core with soft ferromagnetic properties surrounded by a passivating silica layer, and are suitable for magnetically targeted drug delivery and electromagnetic induction heating applications.

  11. Study on the formation of rhenium borides by density functional calculations

    NASA Astrophysics Data System (ADS)

    Agundez, R. R.; Soto, G.; Moreno, M. G.; Reyes-Serrato, A.

    2009-03-01

    The searching of hard and superhard materials is a hot topic in material science. Two known factors are fundamental to get high hardness: (1) high valence-electron density; and (2) high number of electron in covalent bonds. The 5d-transition metals comply with requirement (1); so, the task is to fulfill condition (2) without expanding its native structure. Supposedly this is possible by developing interstitial alloys with elements of moderate electronegativity, like boron and/or carbon. This idea materializes in the very hard ReB2, which scratches the surface of diamond. This work is a study in the formation of rhenium borides by density functional calculations. Here, we want to reveal the changes that would occur in the hexagonal close packed lattice of Re as B is inserted into its interstitial sites. We cover compositions in ReBx from x = 0 to x = 3 in x steps of 0.125. B is positioned in octahedral and tetrahedral interstices of Re, and for each arrangements we have calculated cell volume, cohesive energy, bulk modulus, valence electron concentration, and energy density. Supported by FONDOS CONACYT I0013, SNI-ESTUDIANTES 2008-01, SOLICITUD: 103909

  12. Updated results of a phase I trial of motexafin lutetium-mediated interstitial photodynamic therapy in patients with locally recurrent prostate cancer.

    PubMed

    Verigos, Kosmas; Stripp, Diana C Hsiung; Mick, Rosemarie; Zhu, Timothy C; Whittington, Richard; Smith, Debbie; Dimofte, Andreea; Finlay, Jarod; Busch, Theresa M; Tochner, Zelig A; Malkowicz, S; Glatstein, Eli; Hahn, Stephen M

    2006-01-01

    Locally recurrent prostate cancer after treatment with radiation therapy is a clinical problem with few acceptable treatments. One potential treatment, photodynamic therapy (PDT), is a modality that uses laser light, drug photosensitizer, and oxygen to kill tumor cells through direct cellular cytotoxicity and/or through destruction of tumor vasculature. A Phase I trial of interstitial PDT with the photosensitizer Motexafin lutetium was initiated in men with locally recurrent prostate cancer. In this ongoing trial, the primary objective is to determine the maximally tolerated dose of Motexafin lutetium-mediated PDT. Other objectives include evaluation of Motexafin lutetium uptake from prostate tissue using a spectrofluorometric assay and evaluation of optical properties in the human prostate. Fifteen men with biopsy-proven locally recurrent prostate cancer and no evidence of distant metastatic disease have been enrolled and 14 have been treated. Treatment plans were developed using transrectal ultrasound images. The PDT dose was escalated by increasing the Motexafin lutetium dose, increasing the 732 ran light dose, and decreasing the drug-light interval. Motexafin lutetium doses ranged from 0.5 to 2 mg/kg administered IV 24, 6, or 3 hr prior to 732 ran light delivery. The light dose, measured in real time with in situ spherical detectors was 25-100 J/cm2. Light was delivered via optical fibers inserted through a transperineal brachytherapy template in the operating room. Optical property measurements were made before and after light therapy. Prostate biopsies were obtained before and after light delivery for spectrofluorometric measurements of photosensitizer uptake. Fourteen patients have completed protocol treatment on eight dose levels without dose-limiting toxicity. Grade I genitourinary symptoms that are PDT related have been observed. One patient had Grade II urinary urgency that was urinary catheter related. No rectal or other gastrointestinal PDT-related tox

  13. Computer simulation of monolayer growth kinetics of Fe 2B phase during the paste-boriding process: Influence of the paste thickness

    NASA Astrophysics Data System (ADS)

    Keddam, M.

    2006-11-01

    This paper deals with the effect of boron paste thickness on the study of the monolayer growth kinetics of Fe2B phase forming on AISI 1045 steel by the paste-boriding process. A mathematical diffusion model based on the Fick's phenomenological equations was applied in order to estimate the growth rate constant at (Fe2B/γ-Fe) interface, the layer thickness of iron boride as well as the associated mass gain depending on the boriding parameters such as time, temperature and surface boron concentration related to the boron paste thickness. The simulation results are found to be in a fairly good agreement with the experimental data derived from the literature.

  14. 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

  15. Effect of the boride-nitride hardening on the structure and properties of chromium steel deposited with a flux-cored wire

    NASA Astrophysics Data System (ADS)

    Eremin, E. N.; Losev, A. S.; Borodikhin, S. A.; Ivlev, K. Ye.

    2017-08-01

    Reliability and durability of pipeline valves are largely determined by the resistance of weld sealing surfaces of its shut-off valve, which in its turn depends on the weld metal properties. To improve the durability of valves a new composition of a high chromium flux-cored wire with a boride compounds complex (BN, TiB2, ZrB2) producing weld composite metal is developed. It is stated that the formation of the martensitic matrix with a reduced structural fragments average size due to appearance of dispersed boride-nitride phases in this metal has resulted in high coating hardness and wear resistance.

  16. Scaffolding, ladders, chains, and rare ferrimagnetism in intermetallic borides: synthesis, crystal chemistry and magnetism.

    PubMed

    Goerens, Christian; Brgoch, Jakoah; Miller, Gordon J; Fokwa, Boniface P T

    2011-07-04

    Single-phase polycrystalline samples and single crystals of the complex boride phases Ti(8)Fe(3)Ru(18)B(8) and Ti(7)Fe(4)Ru(18)B(8) have been synthesized by arc melting the elements. The phases were characterized by powder and single-crystal X-ray diffraction as well as energy-dispersive X-ray analysis. They are new substitutional variants of the Zn(11)Rh(18)B(8) structure type, space group P4/mbm (no. 127). The particularity of their crystal structure lies in the simultaneous presence of dumbbells which form ladders of magnetically active iron atoms along the [001] direction and two additional mixed iron/titanium chains occupying Wyckoff sites 4h and 2b. The ladder substructure is ca. 3.0 Å from the two chains at the 4h, which creates the sequence chain-ladder-chain, establishing a new structural and magnetic motif, the scaffold. The other chain (at 2b) is separated by at least 6.5 Å from this scaffold. According to magnetization measurements, Ti(8)Fe(3)Ru(18)B(8) and Ti(7)Fe(4)Ru(18)B(8) order ferrimagnetically below 210 and 220 K, respectively, with the latter having much higher magnetic moments than the former. However, the magnetic moment observed for Ti(8)Fe(3)Ru(18)B(8) is unexpectedly smaller than the recently reported Ti(9)Fe(2)Ru(18)B(8) ferromagnet. The variation of the magnetic moments observed in these new phases can be adequately understood by assuming a ferrimagnetic ordering involving the three different iron sites. Furthermore, the recorded hysteresis loops indicate a semihard magnetic behavior for the two phases. The highest H(c) value (28.6 kA/m), measured for Ti(7)Fe(4)Ru(18)B(8), lies just at the border of those of hard magnetic materials.

  17. Piano-stool lutetium amido and imido compounds supported by a constrained bis(oxazoline)cyclopentadienyl ligand

    SciTech Connect

    Lampland, Nicole L.; Zhu, Jing; Hovey, Megan; Jana, Barun; Ellern, Arkady; Sadow, Aaron D.

    2015-06-25

    {BoMCptet}Lu(CH2Ph)2 (1; BoMCptet = MeC(OxMe2 2C5Me4; OxMe2 = 4,4-dimethyl-2-oxazoline) was prepared in 95% yield from the reaction of BoMCptetH and Lu(CH2Ph)3THF3. Compound 1 reacts with 1 or 2 equiv of H2NCH2R (R = C6H5, 1-C10H7) to give the corresponding imido complexes [{BoMCptet}LuNCH2R]2 (R = C6H5 (2a), 1-C10H7 (2b)) or amido complexes {BoMCptet}Lu(NHCH2R)2 (R = C6H5 (3a), 1-C10H7 (3b)). When isolated, the imido species are insoluble in nonprotic organic solvents. Crystallographic characterization reveals dimeric [{BoMCptet}LuNCH2(1-C10H7)]2 in the solid state. The reaction of 1 and NH3B(C6F5)3 affords crystallographically characterized {BoMCptet}Lu{NHB(C6F5)2}C6F5. This species is proposed to form via a transient lutetium imido, which undergoes C6F5 migration to the lutetium center.

  18. Nano-Borides and Silicide Dispersed Composite Coating on AISI 304 Stainless Steel by Laser-Assisted HVOF Spray Deposition

    NASA Astrophysics Data System (ADS)

    Sharma, Prashant; Majumdar, Jyotsna Dutta

    2014-10-01

    The study concerned a detailed microstructural investigation of nano-borides (Cr2B and Ni3B) and nano-silicide (Ni2Si) dispersed γ-nickel composite coating on AISI 304 stainless steel by HVOF spray deposition of the NiCrBSi precursor powder and subsequent laser surface melting. A continuous wave diode laser with an applied power of 3 kW and scan speed of 20 mm/s in argon shroud was employed. The characterization of the surface in terms of microstructure, microtexture, phases, and composition were carried out and compared with the as-coated (high-velocity oxy-fuel sprayed) surface. Laser surface melting led to homogenization and refinement of microstructures with the formation of few nano-silicides of nickel along with nano-borides of nickel and chromium (Ni3B, Cr2B, and Cr2B3). A detailed microtexture analysis showed the presence of no specific texture in the as-sprayed and laser-melted surface of Cr2B and Ni3B phases. The average microhardness was improved to 750-900 VHN as compared to 250 VHN of the as-received substrate. Laser surface melting improved the microhardness further to as high as 1400 VHN due to refinement of microstructure and the presence of silicides.

  19. The Wyckoff positional order and polyhedral intergrowth in the M3B2- and M5B3-type boride precipitated in the Ni-based superalloys

    PubMed Central

    Hu, X. B.; Zhu, Y. L.; Sheng, N. C.; Ma, X. L.

    2014-01-01

    Ni-based single superalloys play a crucial role in the hottest parts of jet engines. However, due to the complex geometry and macro-segregation during the solidification process, the cast defect such as stray grains is inevitable. Therefore, the transient liquid phase (TLP) bonding which can join several small single crystalline castings together is gradually believed to be an effective method for improving the yields of production of the complex components. The melting point depressant element B is always added into the interlayer filler material. Consequently, borides including the M3B2 and M5B3 phase usually precipitate during the TLP bonding process. So a comprehensive knowledge of the fine structural characteristics of the borides is very critical for an accurate evaluation of the TLP bonding process. In this work, by means of the aberration-corrected transmission electron microscopy, we show, at an atomic scale, the Wyckoff positional order phenomenon of the metal atoms in the unit cell of M3B2- and M5B3-type boride. Meanwhile, the defect along the (001) plane of the above two types of boride are determined to be the polyhedral intergrowth with complex configurations. PMID:25482386

  20. The Wyckoff positional order and polyhedral intergrowth in the M3B2- and M5B3-type boride precipitated in the Ni-based superalloys

    NASA Astrophysics Data System (ADS)

    Hu, X. B.; Zhu, Y. L.; Sheng, N. C.; Ma, X. L.

    2014-12-01

    Ni-based single superalloys play a crucial role in the hottest parts of jet engines. However, due to the complex geometry and macro-segregation during the solidification process, the cast defect such as stray grains is inevitable. Therefore, the transient liquid phase (TLP) bonding which can join several small single crystalline castings together is gradually believed to be an effective method for improving the yields of production of the complex components. The melting point depressant element B is always added into the interlayer filler material. Consequently, borides including the M3B2 and M5B3 phase usually precipitate during the TLP bonding process. So a comprehensive knowledge of the fine structural characteristics of the borides is very critical for an accurate evaluation of the TLP bonding process. In this work, by means of the aberration-corrected transmission electron microscopy, we show, at an atomic scale, the Wyckoff positional order phenomenon of the metal atoms in the unit cell of M3B2- and M5B3-type boride. Meanwhile, the defect along the (001) plane of the above two types of boride are determined to be the polyhedral intergrowth with complex configurations.

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

    SciTech Connect

    Menaka,; Kumar, Bharat; Kumar, Sandeep; Ganguli, A.K.

    2013-04-15

    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 acetate (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.

  2. Photodynamic inactivation of pathogenic species Pseudomonas aeruginosa and Candida albicans with lutetium (III) acetate phthalocyanines and specific light irradiation.

    PubMed

    Mantareva, Vanya; Kussovski, Vesselin; Durmuş, Mahmut; Borisova, Ekaterina; Angelov, Ivan

    2016-11-01

    Photodynamic inactivation (PDI) is a light-associated therapeutic approach suitable for treatment of local acute infections. The method is based on specific light-activated compound which by specific irradiation and in the presence of molecular oxygen produced molecular singlet oxygen and other reactive oxygen species, all toxic for pathogenic microbial cells. The study presents photodynamic impact of two recently synthesized water-soluble cationic lutetium (III) acetate phthalocyanines (LuPc-5 and LuPc-6) towards two pathogenic strains, namely, the Gram-negative bacterium Pseudomonas aeruginosa and a fungus Candida albicans. The photodynamic effect was evaluated for the cells in suspensions and organized in 48-h developed biofilms. The relatively high levels of uptakes of LuPc-5 and LuPc-6 were determined for fungal cells compared to bacterial cells. The penetration depths and distribution of both LuPcs into microbial biofilms were investigated by means of confocal fluorescence microscopy. The photoinactivation efficiency was studied for a wide concentration range (0.85-30 μM) of LuPc-5 and LuPc-6 at a light dose of 50 J cm(-2) from red light-emitting diode (LED; 665 nm). The PDI study on microbial biofilms showed incomplete photoinactivation (<3 logs) for the used gentle drug-light protocol.

  3. Immobilization of lutetium bisphthalocyanine in nanostructured biomimetic sensors using the LbL technique for phenol detection.

    PubMed

    Fernandes, Edson Giuliani R; Brazaca, Lais C; Rodríguez-Mendez, Maria Luz; Saja, Jose Antonio de; Zucolotto, Valtencir

    2011-08-15

    This study describes the development of amperometric sensors based on poly(allylamine hydrochloride) (PAH) and lutetium bisphthalocyanine (LuPc(2)) films assembled using the Layer-by-Layer (LbL) technique. The films have been used as modified electrodes for catechol quantification. Electrochemical measurements have been employed to investigate the catalytic properties of the LuPc(2) immobilized in the LbL films. By chronoamperometry, the sensors present excellent sensitivity (20 nA μM(-1)) in a wide linear range (R(2)=0.994) up to 900 μM and limit of detection (s/n=3) of 37.5 × 10(-8)M for catechol. The sensors have good reproducibility and can be used at least for ten times. The work potential is +0.3 V vs. saturated calomel electrode (SCE). In voltammetry measurements, the calibration curve shows a good linearity (R(2)=0.992) in the range of catechol up to 500 μM with a sensitivity of 90 nA μM(-1) and LD of 8 μM. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Optimizing lutetium 177-anti-carbonic anhydrase IX radioimmunotherapy in an intraperitoneal clear cell renal cell carcinoma xenograft model.

    PubMed

    Muselaers, Constantijn H J; Oosterwijk, Egbert; Bos, Desirée L; Oyen, Wim J G; Mulders, Peter F A; Boerman, Otto C

    2014-01-01

    A new approach in the treatment of clear cell renal carcinoma (ccRCC) is radioimmunotherapy (RIT) using anti-carbonic anhydrase IX (CAIX) antibody G250. To investigate the potential of RIT with lutetium 177 (177Lu)-labeled G250, we conducted a protein dose escalation study and subsequently an RIT study in mice with intraperitoneally growing ccRCC lesions. Mice with intraperitoneal xenografts were injected with 1, 3, 10, 30, or 100 μg of G250 labeled with 10 MBq indium 111 (111In) to determine the optimal protein dose. The optimal protein dose determined with imaging and biodistribution studies was used in a subsequent RIT experiment in three groups of 10 mice with intraperitoneal SK-RC-52 tumors. One group received 13 MBq 177Lu-DOTA-G250, a control group received 13 MBq nonspecific 177Lu-MOPC21, and the second control group was not treated and received 20 MBq 111In-DOTA-G250. The optimal G250 protein dose to target ccRCC in this model was 10 μg G250. Treatment with 13 MBq 177Lu-DOTA-G250 was well tolerated and resulted in significantly prolonged median survival (139 days) compared to controls (49-53 days, p  =  .015), indicating that RIT has potential in this metastatic ccRCC model.

  5. Radiolabeling of substance P with lutetium-177 and biodistribution study in rat pancreatic tumor xenografted nude mice.

    PubMed

    De Araújo, E B; Pujatti, P B; Mengatti, J

    2010-05-10

    Pancreatic tumor (PT) is a neuroendocrine neoplasm that usually origin metastases in the respiratory and gastrointestinal tract. The presence of peptide receptors at the cell membrane of PT constitutes the basis of the clinical use of specific radiolabeled ligands for its diagnosis and targeted therapy. Substance P (SP), an 11-amino acid peptide which has an important role in modulating pain transmission trough neurokinin type 1 (NK1r) and 2 receptors (NK2r), may play a role in the pathogenesis of PT, because approximately 10% of these tumors overexpress NK1r. The aim of the present work was to produce a pure and stable SP analog (DOTA-SP) radiolabeled with lutetium-177 ((177)Lu), and to evaluate its in vivo target to AR42J pancreatic tumor cells in Nude mice, in other to verify if SP can be used in this pancreatic tumor detection and treatment. Substance P was successfully labeled with high yield (>99%) at optimized conditions and kept stable for more than 72 hours at 2-8 degrees C and 4 hours in human plasma. Biodistribution studies showed that SP excretion was mainly performed by renal pathway. In addition, (177)Lu-DOTA-SP showed higher uptake by tumor than normal pancreas, indicating the presence of NK receptors in AR42J pancreatic tumor.

  6. Spectroscopic refractive indices of monoclinic single crystal and ceramic Lutetium oxyorthosilicate (LSO) from 200 to 850 nm

    SciTech Connect

    Jellison Jr, Gerald Earle; Specht, Eliot D; Boatner, Lynn A; Singh, David J; Melcher, Charles L

    2012-01-01

    The four real values of the dielectric function tensor of the monoclinic crystal Lu2SiO5 or lutetium oxyorthosilicate (LSO) have been determined using generalized ellipsometry from 200 to 850 nm. The three principal values are fit to the Sellmeier model, and they indicate that the band gap of LSO is less than ~9 eV. The off-diagonal element 12 is non-zero over the entire spectrum, but it is very close to zero for wavelengths longer than ~400 nm, indicating that structurally monoclinic LSO is nearly optically orthorhombic in this wavelength region. The spectroscopic dielectric functions of three isotropic ceramic LSO samples are presented, which are consistent with the dielectric functions of single-crystal LSO when the effects of porosity are included. As a comparison, the dielectric functions are also determined using relativistic electronic structure and optical calculations based on the recently developed potential functional of Tran and Blaha (Phys. Rev. Lett. 102, 226401 (2009).)

  7. Fabrication and characterization of a 0.5-mm lutetium oxyorthosilicate detector array for high-resolution PET applications.

    PubMed

    Stickel, Jennifer R; Qi, Jinyi; Cherry, Simon R

    2007-01-01

    With the increasing use of in vivo imaging in mouse models of disease, there are many interesting applications that demand imaging of organs and tissues with submillimeter resolution. Though there are other contributing factors, the spatial resolution in small-animal PET is still largely determined by the detector pixel dimensions. In this work, a pair of lutetium oxyorthosilicate (LSO) arrays with 0.5-mm pixels was coupled to multichannel photomultiplier tubes and evaluated for use as high-resolution PET detectors. Flood histograms demonstrated that most crystals were clearly identifiable. Energy resolution varied from 22% to 38%. The coincidence timing resolution was 1.42-ns full width at half maximum (FWHM). The intrinsic spatial resolution was 0.68-mm FWHM as measured with a 30-gauge needle filled with (18)F. The improvement in spatial resolution in a tomographic setting is demonstrated using images of a line source phantom reconstructed with filtered backprojection and compared with images obtained from 2 dedicated small-animal PET scanners. Finally, a projection image of the mouse foot is shown to demonstrate the application of these 0.5-mm LSO detectors to a biologic task. A pair of highly pixelated LSO detections has been constructed and characterized for use as high-spatial-resolution PET detectors. It appears that small-animal PET systems capable of a FWHM spatial resolution of 600 microm or less are feasible and should be pursued.

  8. Structural and Physical Properties Diversity of New CaCu5-Type Related Europium Platinum Borides

    PubMed Central

    2013-01-01

    Three novel europium platinum borides have been synthesized by arc melting of constituent elements and subsequent annealing. They were characterized by X-ray powder and single-crystal diffraction: EuPt4B, CeCo4B type, P6/mmm, a = 0.56167(2) nm, c = 0.74399(3) nm; Eu3Pt7B2, Ca3Al7Cu2 type as an ordered variant of PuNi3, R3̅m, a = 0.55477(2) nm, c = 2.2896(1) nm; and Eu5Pt18B6–x, a new unique structure type, Fmmm, a = 0.55813(3) nm, b = 0.95476(5) nm, c = 3.51578(2) nm. These compounds belong to the CaCu5 family of structures, revealing a stacking sequence of CaCu5-type slabs with different structural units: CaCu5 and CeCo3B2 type in EuPt4B; CeCo3B2 and Laves MgCu2 type in Eu3Pt7B2; and CaCu5-, CeCo3B2-, and site-exchange ThCr2Si2-type slabs in Eu5Pt18B6–x. The striking motif in the Eu5Pt18B6–x structure is the boron-centered Pt tetrahedron [BPt4], which build chains running along the a axis and plays a decisive role in the structure arrangement by linking the terminal fragments of repeating blocks of fused Eu polyhedra. Physical properties of two compounds, EuPt4B and Eu3Pt7B2, were studied. Both compounds were found to order magnetically at 36 and 57 K, respectively. For EuPt4B a mixed-valence state of the Eu atom was confirmed via magnetic and specific heat measurements. Moreover, the Sommerfeld value of the specific heat of Eu3Pt7B2 was found to be extraordinarily large, on the order of 0.2 J/mol K2. PMID:23540751

  9. High-temperature thermochemistry of transition metal borides, silicides and related compounds. Final report

    SciTech Connect

    Klemppa, Ole J.

    2000-10-01

    Earlier this year in collaboration with Dr. Susan V. Meschel we prepared a major review paper which gives a comprehensive summary of what our laboratory has accomplished with support from DOE. This paper is No.43 in the List of Publications provided. It was presented to TMS at its National Meeting in Nashville, TN last March. A copy of the manuscript of this paper was recently mailed to DOE. It has been submitted for publication in Journal of Alloys and Compounds. This review paper summarizes our observed trends in the enthalpies of formation of TR-X and RE-X compounds (where X is a IIIB or IVB element) in their dependence of the atomic number of the transition metal (TR) and the lanthanide metal (RE). In this paper our measured enthalpies of formation for each alloy family are compared for the 3d, 4d and 5d transition metal elements. We also compare our experimental results with predicted values based on Miedema's semi-empirical model. Data are presented for the carbides, silicides, germanides and stannides in Group IVB, and for the borides and aluminides in Group IIIB. During the past year (1999-2000) we have extended our work to compounds of the 3d, 4d and 5d elements with gallium (see papers No.40, No.41, and No.45 in the List of Publications). Fig. 1 (taken from No.45) presents a systematic picture of our experimental values for the most exothermic gallide compounds formed with the transition elements. This figure is characteristic of the other systematic pictures which we have found for the two other IIIB elements which we have studied and for the four IVB elements. These figures are all presented in Ref. No.43. This paper also illustrates how the enthalpy of formation of compounds of the IIIB and IVB elements with the lanthanide elements (with the exception of Pm, Eu and Yb) depend on the atomic number of RE. Finally our results for the RE-X compounds are compared with the predictions of Gschneidner (K.A. Gschneidner, Jr., J. Less Common Metals 17, 1

  10. 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.

  11. Computational-Experimental Processing of Boride/Carbide Composites by Reactive Infusion of Hf Alloy Melts into B4C

    DTIC Science & Technology

    2015-09-16

    infiltration, reactions between the alloy melt and B4C will form an HfB2-HfC/Hf-Y-Ti composite, which will eventually develop an HfO2-Y2O3- TiO2 scale, as...of the pyrochlore phase (or Y2Ti2O7) within an HfO2-Y2O3- TiO2 scale may form as layers of Y2Ti2O7, HfTiO4, cubic-HfO2, or tetragonal-HfO2 as the...processing, a better understanding of the infusion of Figure 1 -- Oxide Scale developed from the ZrO2- Y2O3- TiO2 System to protect a boride/carbide

  12. Prediction of different crystal structure phases in metal borides: A lithium monoboride analog to MgB2

    NASA Astrophysics Data System (ADS)

    Kolmogorov, Aleksey N.; Curtarolo, Stefano

    2006-05-01

    Modern compound prediction methods can efficiently screen large numbers of crystal structure phases and direct the experimental search for new materials. One of the most challenging problems in alloy theory is the identification of stable phases with a never seen prototype; such predictions do not always follow rational strategies. While performing ab initio data mining of intermetallic compounds we made an unexpected discovery: even in such a well-studied class of systems as metal borides there are previously unknown layered phases comparable in energy to the existing ones. With ab initio calculations we show that the new metal-sandwich (MS) lithium monoboride phases are marginally stable under ambient conditions but become favored over the known stoichiometric compounds under moderate pressures. The MS lithium monoboride exhibits electronic features similar to those in magnesium diboride and is expected to be a good superconductor.

  13. Feasibility of repeated sequential treatments of RIF-1 tumors with photodynamic therapy (PDT) using lutetium texaphyrin (PCI-0123)

    NASA Astrophysics Data System (ADS)

    Miles, Dale R.; Parker, Lynn M.; Thiemann, Patricia A.; Woodburn, Kathryn W.; Young, Stuart W.

    1997-05-01

    Lutetium texaphyrin (PCI-0123) is currently in clinical trials as a PDT agent for the treatment of cancer patients. The drug is cleared rapidly from the plasma, and photoirradiation can be performed shortly after drug administration.T He photosensitizer as yet does not appear to elicit any significant skin photosensitivity. These characteristics favor frequent multiple PDT treatments with PCI-0123. In order to support repeated PDT treatments in the clinic, the safety of multiple drug dosing was studied in rats and mice. In rats, each group received 5 consecutive daily intravenous administrations of 5, 15, 30, or 60 mg/kg/day of PCI-0123. There were no deaths in any of the groups, and no drug-related effects were detected in the 5 mg/kg/day group. In mice, there were no observable signs of toxicity after consecutive daily administration of 10 micrometers ol/kg/day of PCI-0123 for 13 days. The feasibility and efficacy of repeated PDT treatments were assessed in C3H mice bearing RIF-1 tumors. Repeated PDT proved to be superior to a single PDT treatment. Repeated PDT treatments were well tolerated. Seven PDT treatments were administered over a nine day period without significant toxicity while achieving good therapeutic responses. All six groups receiving repeated PDT treatments showed an improved response compared to groups receiving a single PDT cycle, and the improvement was statistically significant for five of these groups. Sixty-two percent of mice receiving four sequential daily treatments were cured, and daily treatments were superior to regimens with longer intervals between PDT cycles.

  14. In vivo reflectance measurement of optical properties, blood oxygenation and motexafin lutetium uptake in canine large bowels, kidneys and prostates.

    PubMed

    Solonenko, Michael; Cheung, Rex; Busch, Theresa M; Kachur, Alex; Griffin, Gregory M; Vulcan, Theodore; Zhu, Timothy C; Wang, Hsing-Wen; Hahn, Stephen M; Yodh, A G

    2002-03-21

    Motexafin lutetium (MLu) is a second-generation photosensitizer for photodynamic therapy (PDT) of cancer. We have developed and applied a diffuse optical reflectance spectrometer for in vivo measurement of MLu uptake, optical properties, haemoglobin concentration and haemoglobin oxygen saturation in normal canine large bowels, kidneys and prostates. The probe consists of a broadband fibre-optic-coupled light source and detector fibres placed at various distances from the source fibre to collect reflected light. An analysis based on the diffusion approximation of the photon transport equation was used to recover tissue optical properties from the reflectance measurements. The instrumentation and analysis methods were validated using measurements from homogeneous, highly scattering phantoms with known MLu concentrations. The same techniques were then used to estimate chromophore concentrations of normal canine large bowels, kidneys and prostates. We estimated (mean (standard deviation)) total haemoglobin concentrations of 119 (25), 340 (92) and 51 (11) microM in the large bowels, kidneys and prostates of four dogs, respectively; tissue blood oxygen saturations in these same organs were 75 (15), 76 (21) and 74 (16) per cent, respectively. Tissue MLu concentrations (mg l(-1)) were estimated from data taken 3.5 h after injection of a 2 mg kg(-1) injected dose; data from three dogs gave concentrations of 2.4 (0.4) in large bowels, 6.8 (1.3) in kidneys and 2.2 (1.1) in prostates. The reduced scattering coefficients, mu's, estimated for large bowels, kidneys and prostates at 730 nm were, respectively: 10.1 (1.3), 19.6 (4.0) and 12.7 (0.6) cm(-1). We observed significant variability in MLu uptake, tissue scattering and haemoglobin concentration between organs and even between the same organ in different dogs. This class of in situ optical property measurement may be desirable to individualize PDT drug and light delivery.

  15. Semiautomated labelling and fractionation of yttrium-90 and lutetium-177 somatostatin analogues using disposable syringes and vials.

    PubMed

    Asti, Mattia; Atti, Giulia; Iori, Michele; Farioli, Daniela; Filice, Angelina; Versari, Annibale

    2012-11-01

    The treatment of tumours expressing somatostatin receptors with yttrium-90 (90Y)-labelled and lutetium-177 (177Lu)-labelled somatostatin analogues is one of the most interesting therapeutic approaches adopted in nuclear medicine in recent years. However, the process of synthesis and fractionation of these radiopharmaceuticals is still mainly carried out manually despite the high radiation exposure to the operators and the need to comply with good manufacturing practices. In this study a semiautomatic synthesizer [automatic dose dispenser (ADD-2)] using only disposable syringes and vials has been presented. Small-scale syntheses (185-555 MBq) of 90Y/177Lu-DOTATATE were performed by adding the appropriate amount of peptide to a 90Y/177Lu chloride solution (n=10). The radionuclide/peptide molar ratio was 1 : 17 and 1 : 2 for 90Y and 177Lu, respectively. The solutions were buffered to 4.6 pH by ascorbate buffer and heated at 90°C for 30 min. Radiochemical purity was assessed by two independent radio-thin-layer chromatography systems. The solutions were fractioned to mimic the preparation of patient doses. All synthesis and fractionation steps were performed using ADD-2. The radiochemical yield was 92 ± 3% for 90Y and 97 ± 1% for 177Lu labelling. Radiochemical purity was more than 99.5%. The accuracy and reproducibility of the instrument in transferring and fractionating radioactive solutions were high (maximal error ≈ 5%). ADD-2 appears suitable for use in clinical preparations of 90Y/177Lu-DOTATATE with therapeutic amounts of precursors (20-30 GBq). The operator's exposure to radiation by using ADD-2 in comparison with manual preparations is under investigation.

  16. A novel glucose sensor using lutetium phthalocyanine as redox mediator in reduced graphene oxide conducting polymer multifunctional hydrogel.

    PubMed

    Al-Sagur, H; Komathi, S; Khan, M A; Gurek, A G; Hassan, A

    2017-06-15

    Herein, we report a scalable synthesis of multifunctional conducting polyacrylic acid (PAA) hydrogel (MFH) integrated with reduced grapheme oxide (rGO), vinyl substituted polyaniline (VS-PANI) and lutetium Phthalocyanine (LuPc2) as three dimensional robust matrix for glucose oxidase (GOx) immobilization (PAA-rGO/VS-PANI/LuPc2/GOx-MFH). We have integrated the multicomponents such as PAA with rGO, and VS-PANI through free radical polymerization using methylene bis-acrylamide, and ammonium persulphate as the cross linker and initiator. The LuPc2 was then doped to form multifunctional hydrogel (PAA-rGO/VS-PANI/LuPc2-MFH). Finally, biosensor was fabricated by immobilizing GOx into PAA-rGO/VS-PANI/LuPc2-MFH and subsequently used for electrochemical detection of glucose. The PAA-rGO/VS-PANI/LuPc2/GOx-MFH biosensor exhibited high sensitivity (15.31μAmM(-1)cm(-2)) for the detection of glucose over a concentration range of 2-12mM with a low detection limit of 25µm. The PAA-rGO/VS-PANI/LuPc2-MFH biosensor showed a fast response time (1s) to the addition of glucose with high storage stability of 3 months. The real sample analysis reveals that PAA-rGO/VS-PANI/LuPc2/GOx-MFH could be effectively used as an electrochemical biosensor in industrial as well clinical diagnosis. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Quantifying public radiation exposure related to lutetium-177 octreotate therapy for the development of a safe outpatient treatment protocol.

    PubMed

    Olmstead, Craig; Cruz, Kyle; Stodilka, Robert; Zabel, Pamela; Wolfson, Robert

    2015-02-01

    Radionuclide therapies, including treatment of neuroendocrine tumors with lutetium-177 (Lu-177) octreotate, often involve hospital admission to minimize radiation exposure to the public. Overnight admission due to Lu-177 octreotate therapy incurs additional cost for the hospital and is an inconvenience for the patient. This study endeavors to characterize the potential radiation risk to caregivers and the public should Lu-177 octreotate therapies be performed on an outpatient basis. Dose rate measurements of radiation emanating from 10 patients were taken 30 min, 4, and 20 h after initiation of Lu-177 octreotate therapy. Instadose radiation dose measurement monitors were also placed around the patients' rooms to assess the potential cumulative radiation exposure during the initial 30 min-4 h after treatment (simulating the hospital-based component of the outpatient model) as well as 4-20 h after treatment (simulating the discharged outpatient portion). The mean recorded dose rate at 30 min, 4, and 20 h after therapy was 20.4, 14.0, and 6.6 μSv/h, respectively. The majority of the cumulative dose readings were below the minimum recordable threshold of 0.03 mSv, with a maximum dose recorded of 0.18 mSv. Given the low dose rate and cumulative levels of radiation measured, the results support that an outpatient Lu-177 octreotate treatment protocol would not jeopardize public safety. Nevertheless, the concept of ALARA still requires that detailed radiation safety protocols be developed for Lu-177 octreotate outpatients to minimize radiation exposure to family members, caregivers, and the general public.

  18. Bioelectronic tongue based on lipidic nanostructured layers containing phenol oxidases and lutetium bisphthalocyanine for the analysis of grapes.

    PubMed

    Medina-Plaza, C; de Saja, J A; Rodriguez-Mendez, M L

    2014-07-15

    In this work, a multisensor system formed by nanostructured voltammetric biosensors based on phenol oxidases (tyrosinase and laccase) has been developed. The enzymes have been incorporated into a biomimetic environment provided by a Langmuir-Blodgett (LB) film of arachidic acid (AA). Lutetium bisphthalocyanine (LuPc2) has also been introduced in the films to act as electron mediator. The incorporation of the enzymes to the floating layers to form Tyr/AA/LuPc2 and Lac/AA/LuPc2 films has been confirmed by the expansion in the surface pressure isotherms and by the AFM images. The voltammetric response towards six phenolic compounds demonstrates the enhanced performance of the biosensors that resulted from a preserved activity of the tyrosinase and laccase combined with the electron transfer activity of LuPc2. Biosensors show improved detection limits in the range of 10(-7)-10(-8) mol L(-1). An array formed by three sensors AA/LuPc2, Tyr/AA/LuPc2 and Lac/AA/LuPc2 has been employed to discriminate phenolic antioxidants of interest in the food industry. The Principal Component Analysis scores plot has demonstrated that the multisensor system is able to discriminate phenols according to the number of phenolic groups attached to the structure. The system has also been able to discriminate grapes of different varieties according to their phenolic content. This good performance is due to the combination of four factors: the high functionality of the enzyme obtained using a biomimetic immobilization, the signal enhancement caused by the LuPc2 mediator, the improvement in the selectivity induced by the enzymes and the complementary activity of the enzymatic sensors demonstrated in the loading plots. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. The effect of thermocycling liquid boronizing on the thickness of the boride layer and the transition zone

    SciTech Connect

    Oezsoy, A.; Yaman, Y.M. )

    1993-07-15

    Boronizing is a thermo-diffusion surface treatment, which is defined as enrichment of the surface of a workpiece with boron by means of thermo-chemical treatment. The processes are based on chemical or electrochemical reactions between the boron source and the respective base metal. Boron sources or boronizing compounds are solid, liquid or gas. Boride coatings, or the formation of boride compounds near the surface have been achieved by: (a) chemical methods; using gas boronizing agents, by immersion in molten salts, electrolysis and by pack cementation with powders; (b) physical methods; such as boron ion implantation, physical vacuum deposition, sputtering and ion plating. The methods of thermocycling treatment are used for intensification of the diffusion processes and forming more uniform microstructures and grain refinement. Krishtal and Kenis reported that the diffusion processes are accelerated with increasing grain boundary length, vacancy concentration, dislocation density inside the grains, and stress gradients in the thermocycling treatment. In practice, the type of structure favoring the intensification of diffusion processes is obtained using thermocycling treatment (TCT), either as a preliminary treatment before thermo-chemical treatment (TChT) or as a combined process before and during the thermochemical treatment. The steel is usually heated to 30-50 C above Ac[sub 1] and cooled to 50-100 C below Ar[sub 1]. Such treatment achieves an increase in the diffusion layer thickness, grain refinement and formation of a polygonal structure in the bulk of the metal. The combined use of TCT and TChT was studied during carburization of steel with a solid carburizer. It was demonstrated that, at the same duration of isothermal treatment (15 h), 5 cycles of 880-750 C, TCT produce grain size No. 5-6 in the bulk and grain size No. 9-10 in the diffusion layer, while the thickness of that layer increases 1.5 times. Improved fatigue resistance was also recorded.

  20. Lu2@C2n (2n = 82, 84, 86): Crystallographic Evidence of Direct Lu-Lu Bonding between Two Divalent Lutetium Ions Inside Fullerene Cages.

    PubMed

    Shen, Wangqiang; Bao, Lipiao; Wu, Yongbo; Pan, Changwang; Zhao, Shasha; Fang, Hongyun; Xie, Yunpeng; Jin, Peng; Peng, Ping; Li, Fang-Fang; Lu, Xing

    2017-07-26

    Although most of the M2C2n-type metallofullerenes (EMFs) tend to form carbide cluster EMFs, we report herein that Lu-containing EMFs Lu2C2n (2n = 82, 84, 86) are actually dimetallofullerenes (di-EMFs), namely, Lu2@Cs(6)-C82, Lu2@C3v(8)-C82, Lu2@D2d(23)-C84, and Lu2@C2v(9)-C86. Unambiguous X-ray results demonstrate the formation of a Lu-Lu single bond between two lutetium ions which transfers four electrons in total to the fullerene cages, thus resulting in a formal divalent state for each Lu ion. Population analysis indicates that each Lu atom formally donates a 5d electron and a 6s electron to the cage with the remaining 6s electron shared with the other Lu atom to form a Lu-Lu single bond so that only four electrons are transferred to the fullerene cages with the formal divalent valence for each lutetium ion. Accordingly, we confirmed both experimentally and theoretically that the dominating formation of di-EMFs is thermodynamically very favorable for Lu2C2n isomers.

  1. Beta emitters rhenium-188 and lutetium-177 are equally effective in radioimmunotherapy of HPV-positive experimental cervical cancer.

    PubMed

    Phaeton, Rebecca; Jiang, Zewei; Revskaya, Ekaterina; Fisher, Darrell R; Goldberg, Gary L; Dadachova, Ekaterina

    2016-01-01

    Cervical cancer caused by the infection with the human papillomavirus (HPV) remains the fourth leading killer of women worldwide. Therefore, more efficacious treatments are needed. We are developing radioimmunotherapy (RIT) of HPV-positive cervical cancers by targeting E6 and E7 viral oncoproteins expressed by the cancer cells with the radiolabeled monoclonal antibodies (mAbs). To investigate the influence of different radionuclides on the RIT efficacy-we performed RIT of experimental cervical cancer with Rhenium-188 ((188) Re) and Lutetium-177 ((177) Lu)-labeled mAb C1P5 to E6. The biodistribution of (188) Re- and (177) Lu-labeled C1P5 was performed in nude female mice bearing CasKi cervical cancer xenografts and the radiation dosimetry calculations for the tumors and organs were carried out. For RIT the mice were treated with 7.4 MBq of either (188) Re-C1P5 or (177) Lu-C1P5 or left untreated, and observed for their tumor size for 28 days. The levels of (188) Re- and (177) Lu-C1P5 mAbs-induced double-strand breaks in CasKi tumors were compared on days 5 and 10 post treatment by staining with anti-gamma H2AX antibody. The radiation doses to the heart and lungs were similar for both (177) Lu-C1P5 and (188) Re-C1P5. The dose to the liver was five times higher for (177) Lu-C1P5. The doses to the tumor were 259 and 181 cGy for (177) Lu-C1P5 and (188) Re-C1P5, respectively. RIT with either (177) Lu-C1P5 or (188) Re-C1P5 was equally effective in inhibiting tumor growth when each was compared to the untreated controls (P = 0.001). On day 5 there was a pronounced staining for gamma H2AX foci in (177) Lu-C1P5 group only and on day 10 it was observed in both (177) Lu-C1P5 and (188) Re-C1P5 groups. (188) Re- and (177) Lu-labeled mAbs were equally effective in arresting the growth of CasKi cervical tumors. Thus, both of these radionuclides are candidates for the clinical trials of this approach in patients with advanced, recurrent or metastatic cervical cancer. © 2015 The

  2. Performance Evaluation of microPET: A High-Resolution Lutetium Oxyorthosilicate PET Scanner for Animal Imaging

    PubMed Central

    Chatziioannou, Arion F.; Cherry, Simon R.; Shao, Yiping; Silverman, Robert W.; Meadors, Ken; Farquhar, Thomas H.; Pedarsani, Marjan; Phelps, Michael E.

    2012-01-01

    A new dedicated PET scanner, microPET, was designed and developed at the University of California, Los Angeles, for imaging small laboratory animals. The goal was to provide a compact system with superior spatial resolution at a fraction of the cost of a clinical PET scanner. Methods The system uses fiberoptic readout of individually cut lutetium oxyorthosilicate (LSO) crystals to achieve high spatial resolution. Each microPET detector consists of an 8 × 8 array of 2 × 2 × 10-mm LSO scintillation crystals that are coupled to a 64-channel photomultiplier tube by optical fibers. The tomograph consists of 30 detectors in a continuous ring with a 17.2-cm diameter and fields of view (FOVs) of 11.25 cm in the transaxial direction and 1.8 cm in the axial direction. The system has eight crystal rings and no interplane septa. It operates exclusively in the three-dimensional mode and has an electronically controlled bed that is capable of wobbling with a radius of 300 µm. We describe the performance of the tomograph in terms of its spatial, energy and timing resolution, as well as its sensitivity and counting-rate performance. We also illustrate its overall imaging performance with phantom and animal studies that demonstrate the potential applications of this device to biomedical research. Results Images reconstructed with three-dimensional filtered back projection show a spatial resolution of 1.8 mm at the center of the FOV (CFOV), which remains < 2.5 mm for the central 5 cm of the transaxial FOV. The resulting volumetric resolution of the system is < 8 µL. The absolute system sensitivity measured with a 0.74 MBq (20 µCi) 68Ge point source at the CFOV is 5.62 Hz/kBq. The maximum noise equivalent counting rate obtained with a 6.4-cm diameter cylinder spanning the central 56% of the FOV is 10 kcps, whereas the scatter fraction is 37% at the CFOV for an energy window of 250–650 keV and the same diameter cylinder. Conclusion This is the first PET scanner to use the new

  3. Chemoradiation therapy using cyclopamine-loaded liquid-lipid nanoparticles and lutetium-177-labeled core-crosslinked polymeric micelles.

    PubMed

    You, Jian; Zhao, Jun; Wen, Xiaoxia; Wu, Chunhui; Huang, Qian; Guan, Fada; Wu, Richard; Liang, Dong; Li, Chun

    2015-03-28

    Cyclopamine (CPA), a potent inhibitor of the Hedgehog pathway, has produced promising anticancer results in a number of preclinical studies. CPA has also been found to enhance tumor response to radiation therapy. However, CPA is water insoluble. A drug delivery system suitable for systemic administration of CPA is needed before CPA can be considered for clinical translation. We hypothesized that CPA solubilized in a liquid-lipid nanoparticle system (CPA-LLP) for intravenous injection would have desirable pharmacokinetic properties and increased anticancer efficacy. We further hypothesized that CPA-LLP would enhance the response of tumor cells to targeted radiotherapy delivered selectively through intratumoral injection of lutetium-177 bound to core-crosslinked polymeric micelles (CCPM-(177)Lu). We tested the combination therapy in 4T1 murine breast cancer and Miapaca-2 human pancreatic adenocarcinoma models. The results showed that CPA-LLP had higher antitumor cytotoxicity than free CPA (IC50 values [mean±SEM]: 2.7±0.2μM vs. 11.3±1.2μM against 4T1 cells; 1.8±0.2 vs. 17.1±1.26μM against Miapaca-2 cells; p<0.0001). In both cell lines, CPA-LLP resulted in significantly lower clonogenicity than free CPA (p<0.05). Moreover, in both cell lines, CPA-LLP significantly enhanced the cell response to CCPM-(177)Lu radiotherapy as measured by clonogenic assay (p<0.05). In 4T1 and Miapaca-2 mouse xenograft models, the combination of CPA-LLP and CCPM-(177)Lu delayed tumor growth more than either monotherapy did alone. In the 4T1 tumor model, tumor size at 16days after treatment was significantly smaller with the combination therapy than with all the other treatments. In the Miapaca-2 model, the combination therapy resulted in the highest rate of mouse survival and prevented tumor relapse. In conclusion, the combination of CPA-LLP and CCPM-(177)Lu was an effective strategy for treating breast and pancreatic cancer and deserves further investigation. Copyright © 2015

  4. 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

  5. Precipitation of Niobium Boride Phases at the Base Metal/Weld Metal Interface in Dissimilar Weld Joints

    NASA Astrophysics Data System (ADS)

    Výrostková, Anna; Kepič, Ján; Homolová, Viera; Falat, Ladislav

    2015-07-01

    In this work, the analysis of failure mechanism in the heat affected zone is described in dissimilar weld joints between advanced martensitic steel T92 and Ni-base weld metal. The joints were treated with two different post-weld heat treatments and tested. For the creep, tensile, and Charpy impact tests, the samples with interfacially located notch were used. Moreover long term aging at 625 °C was applied before the tensile and notch toughness tests. Decohesion fractures ran along carbides at the T92 BM/WM interfaces in case of the modified PWHT, whereas type IV cracking was the prevailing failure mechanism after the classical PWHT in the creep test. In the notch tensile and Charpy impact tests, with the notch at T92 base metal/weld metal interface, fractures ran along the interface with a hard phase on the fracture surface along with the ductile dimple and brittle quasi-cleavage fracture. The phase identified as niobium boride (either NbB and/or Nb3B2) was produced during welding at the end of the solidification process. It was found in the welds regardless of the post-weld heat treatment and long-term aging.

  6. Phase stability and incompressibility of tungsten boride (WB) researched by in-situ high pressure x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Fan, Cong; Liu, Chenji; Peng, Fang; Tan, Ning; Tang, Mingjun; Zhang, Qiang; Wang, Qiming; Li, Fengjiao; Wang, Jianghua; Chen, Ying; Liang, Hao; Guan, Shixue; Yang, Ke; Liu, Jing

    2017-09-01

    The binary tungsten boride, WB, has potential industrial applications as it not only has a high melting point but is generally harder and less compressible than the pure metals. Here, the physical and mechanical properties (phase stability, bulk modulus and compressibility) of WB were investigated by in situ high-pressure x-ray diffraction and theoretical calculations. Its crystal structure still remains stable even at the highest pressure of 63.7 GPa and room temperature for the diamond-anvil cell experiments. The pressure-volume (P-V) data were fitted using the Birch-Murnaghan EOS and the Vinet EOS to obtain the isothermal bulk modulus, K0 = 452 (4) GPa and 451(3) GPa and its pressure derivative, K0‧ = 4 (fixed) in the two sets of experiments with two different pressure transmitting mediums (PTMs), respectively. The excellent bulk modulus (K0) is attributed to the high valence electron density of W atom, the layered and chain-like crystal structure of WB and the strong chemical bonds formed by W and B atoms. Besides, anisotropic compression behavior of the unit-cell axes (a- and c-axes) of WB is manifested by experimental observations and theoretical calculations. This remarkably elastic property is closely related to the strongly directional bonding between W and B atoms.

  7. 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.

  8. Initial stages of Lutetium growth on Si (111)-7 × 7 probed by STM and core-level photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Smykalla, Lars; Shukrynau, Pavel; Hietschold, Michael

    2017-09-01

    The interaction of small amounts of Lutetium with the Si (111)-7 × 7 reconstructed surface was investigated in detail using a combination of Scanning Tunneling Microscopy (STM) and Photoelectron Spectroscopy (XPS and UPS). Various immobile and also fastly moving atoms and nanocluster were found in the initial growth of the Lu/Si interface. Density functional theory calculations and photoelectron spectroscopy results suggest that the most attractive adsorption sites for the Lu atoms are basins around Si rest-atoms and there is no strong interaction between Lu and Si at the initial steps of film growth. However Lu nanocluster could also be found on other adsorption sites which results in a different voltage dependence in STM. Coverage-dependent STM images reveal the growth of a closed Lu metal overlayer by joining of the clusters. The existence of a stoichiometric Lu silicide compound was not detected on the surface in the initial growth for deposition at room temperature.

  9. Redox properties of mixed lutetium/yttrium nitride clusterfullerenes: endohedral Lu(x)Y(3-x)N@C80(I) (x = 0-3) compounds.

    PubMed

    Tarábek, Ján; Yang, Shangfeng; Dunsch, Lothar

    2009-05-11

    The redox behavior of mixed lutetium/yttrium nitride clusterfullerenes of the series Lu(x)Y(3-x)N@C(80)(I(h), x = 0-3) is studied for the first time by means of cyclic voltammetry, fast-scan cyclic voltammetry, square-wave voltammetry, and electron paramagnetic resonance (EPR) spectroelectrochemistry. A reversible single-electron-transfer process, which does not result in an EPR signal, is detected during the anodic oxidation sweep of cyclic voltammetry experiments performed at different temperatures (296 and 360 K). The cathodic reduction sweep reveals a rather complex response for all the four clusterfullerenes--with up to three irreversible reduction steps. By correlating the results of fast-scan and square-wave voltammetry and combining them with simulations of the voltammograms, we are able to propose a reduction mechanism for the Lu(x)Y(3-x)N@C(80)(I) (x = 0-3) fullerenes.

  10. Fabrication and microstructure of cerium doped lutetium aluminum garnet (Ce:LuAG) transparent ceramics by solid-state reaction method

    SciTech Connect

    Li, Junlang; Xu, Jian; Shi, Ying; Qi, Hongfang; Xie, Jianjun; Lei, Fang

    2014-07-01

    Highlights: • We fabricate Ce doped lutetium aluminum garnet ceramics by solid-state method. • The raw materials include Lu{sub 2}O{sub 3} nanopowders synthesized by co-precipitation method. • The density of the transparent ceramics reach 99.7% of the theoretical value. • The optical transmittance of the bulk ceramic at 550 nm was 57.48%. • Some scattering centers decrease the optical characteristic of the ceramic. - Abstract: Polycrystalline Ce{sup 3+} doped lutetium aluminum garnet (Ce:LuAG) transparent ceramics fabricated by one step solid-state reaction method using synthetic nano-sized Lu{sub 2}O{sub 3}, commercial α-Al{sub 2}O{sub 3} and CeO{sub 2} powders were investigated in this paper. The green compacts shaped by the mixed powders were successfully densified into Ce:LuAG transparent ceramics after vacuum sintering at 1750 °C for 10 h. The in-line optical transmittance of the Ce:LuAG ceramic made by home-made Lu{sub 2}O{sub 3} powders could reach 57.48% at 550 nm, which was higher than that of the ceramic made by commercial Lu{sub 2}O{sub 3} powders (22.96%). The microstructure observation showed that light scattering centers caused by micro-pores, aluminum segregation and refraction index inhomogeneities induced the decrease of optical transparency of the Ce:LuAG ceramics, which should be removed and optimized in the future work.

  11. Phase 2 Study of Lutetium 177-Labeled Anti-Carbonic Anhydrase IX Monoclonal Antibody Girentuximab in Patients with Advanced Renal Cell Carcinoma.

    PubMed

    Muselaers, Constantijn H J; Boers-Sonderen, Marye J; van Oostenbrugge, Tim J; Boerman, Otto C; Desar, Ingrid M E; Stillebroer, Alexander B; Mulder, Sasja F; van Herpen, Carla M L; Langenhuijsen, Johan F; Oosterwijk, Egbert; Oyen, Wim J G; Mulders, Peter F A

    2016-05-01

    Despite advances in the treatment of metastatic clear cell renal cell carcinoma (ccRCC), there is still an unmet need in the treatment of this disease. A phase 2 radioimmunotherapy (RIT) trial with lutetium 177 ((177)Lu)-girentuximab was initiated to evaluate the efficacy of this approach. In this nonrandomized single-arm trial, patients with progressive metastatic ccRCC who met the inclusion criteria received 2405 MBq/m(2) of (177)Lu-girentuximab intravenously. In the absence of persistent toxicity and progressive disease, patients were eligible for retreatment after 3 mo with 75% of the previous activity dose. A total of 14 patients were included. After the first therapeutic infusion, eight patients (57%) had stable disease (SD) and one (7%) had a partial regression. The treatment was generally well tolerated but resulted in grade 3-4 myelotoxicity in most patients. After the second cycle, continued SD was observed in five of six patients, but none were eligible for retreatment due to prolonged thrombocytopenia. In conclusion, RIT with (177)Lu-girentuximab resulted in disease stabilization in 9 of 14 patients with progressive metastatic ccRCC, but myelotoxicity prevented retreatment in some patients. We investigated the efficacy of lutetium 177-girentuximab radioimmunotherapy in patients with metastatic kidney cancer. The treatment resulted in disease stabilization in 9 of 14 patients. The main toxicity was prolonged low blood cell counts. ClinicalTrials.gov identifier: NCT02002312 (https://clinicaltrials.gov/ct2/show/NCT02002312). Copyright © 2015 European Association of Urology. Published by Elsevier B.V. All rights reserved.

  12. Anomalous effect of vanadium boride seeding on thermoelectric properties of YB{sub 22}C{sub 2}N

    SciTech Connect

    Prytuliak, A.; Maruyama, S.; Mori, T.

    2013-05-15

    Highlights: ► We doped YB{sub 22}C{sub 2}N; the long awaited n-type counterpart to p-type boron carbide. ► VB{sub 2} seeding of YB{sub 22}C{sub 2}N showed striking results. ► Thermal treatment effects led to VB{sub 2} being intrinsically doped. ► Large increase of both Seebeck coefficient and electrical conductivity was obtained. - Abstract: Vanadium boride seeded YB{sub 22}C{sub 2}N were synthesized and the thermoelectric properties investigated. YB{sub 22}C{sub 2}N is representative of the series of rare earth borocarbonitrides which is the potential long awaited n-type counterpart to p-type boron carbide. VB{sub 2} seeded samples of YB{sub 22}C{sub 2}N were prepared using VB{sub 2} directly as an initial additive and V{sub 2}O{sub 3} which also results in formation of vanadium diboride in the final product. The resistivity and Seebeck coefficient of samples were measured in the temperature range of 323 K to 1073 K. A dramatic effect of thermal treatment on the Seebeck coefficient of VB{sub 2} seeded samples was observed, and it is indicated that there is possible partial intrinsic doping of vanadium into YB{sub 22}C{sub 2}N. VB{sub 2} is revealed to be a promising additive to improve the thermoelectric properties of YB{sub 22}C{sub 2}N. An enhancement of more than 220% of the maximum absolute value of the Seebeck coefficient was obtained while the resistivity was also reduced considerably.

  13. Crystal structures and compressibility of novel iron borides Fe2B7 and FexB50 synthesized at high pressure and high temperature

    NASA Astrophysics Data System (ADS)

    Bykova, E.; Gou, H.; Bykov, M.; Hanfland, M.; Dubrovinsky, L.; Dubrovinskaia, N.

    2015-10-01

    We present here a detailed description of the crystal structures of novel iron borides, Fe2B7 and FexB50 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 Fe2B7 possesses short incompressible B-B bonds, which make it as stiff as diamond in one crystallographic direction. The volume compressibility of Fe2B7 (the bulk modulus K0= 259(1.8) GPa, K0‧= 4 (fixed)) is even lower than that of FeB4 and comparable with that of MnB4, known for high bulk moduli among 3d metal borides. FexB50 adopts the structure of the tetragonal δ-B, in which Fe atoms occupy an interstitial position. FexB50 does not show considerable anisotropy in the elastic behavior.

  14. Ultraviolet Spectroscopy of Metal-Poor Stars: New Detections of Phosphorus, Germanium, Arsenic, Selenium, Cadmium, Tellurium, Lutetium, Osmium, Iridium, Platinum, Gold, and More!

    NASA Astrophysics Data System (ADS)

    Roederer, Ian U.

    2015-01-01

    Ultraviolet spectroscopy with HST/STIS provides a 30% increase in the number of elements that can be detected in metal-poor stars. Although nearly every element from hydrogen through bismuth is probably present in most metal-poor stars, not all elements can be detected. The resonance lines of the dominant species of some elements are only found in the UV in late-type stars. The chemical compositions of these stars reflect the history of stellar nucleosynthesis from the first stars to today. Here, I present a summary of recent work that has expanded the chemical inventory in metal-poor stars using UV spectroscopy conducted using HST/STIS. The highlights include new detections of phosphorus, germanium, arsenic, selenium, cadmium, tellurium, lutetium, osmium, iridium, platinum, and gold in metal-poor stars. These detections reveal new insights into stellar nucleosynthesis in the earliest generations of massive stars, provide new constraints on the r-process, and open new channels for chemically-tagging stars that have assembled to form the Milky Way stellar halo.

  15. Development of a new bombesin analog radiolabeled with lutetium-177: in vivo evaluation of the biological properties in Balb-C mice.

    PubMed

    Pujatti, P B; Santos, J S; Massicano, A V F; Mengatti, J; De Araújo, E B

    2010-05-10

    In this work we describe the first results of radiolabeling with lutetium-177 ((177)Lu) and in vivo biodistribution and pharmacokinetics studies in normal Balb-c mice of a new bombesin analog (BEFG2)--DOTA-Phe-X-BBN(6-14), where X is a spacer of two aminoacids. Bombesin (BBN) is an amphibian analog of human gastrin releasing peptide (GRP). Development of radiolabeled BBN derivatives as agents for diagnostic imaging and systemic radiotherapy has increased considerable because of the observation that GRP receptors (GRPr) are over-expressed in a variety of human tumor cells, such as prostate tumor cells. (177)Lu-labeled peptides are attractive due to the excellent radiophysical properties and commercial availability of the radiometal. BEFG2 was successfully labeled with high yield and kept stable for more than 96 hours at 2-8 degrees C and 1 hour in human plasma. Data analysis obtained from the in vivo studies showed that the amount of BEFG2 present in plasma decreased rapidly and became almost undetectable at 60 min p.i., indicating rapid peptide excretion, which is performed mainly by renal pathway. In addition, biodistribution and single photon emission tomography showed low abdominal accumulation of (177)Lu-DOTA- Phe-X-BBN(6-14), indicating that this analog is a potential candidate for tumors target therapy.

  16. Lutetium (177) PSMA radionuclide therapy for men with prostate cancer: a review of the current literature and discussion of practical aspects of therapy.

    PubMed

    Emmett, Louise; Willowson, Kathy; Violet, John; Shin, Jane; Blanksby, Ashley; Lee, Jonathan

    2017-03-01

    Prostate-specific membrane antigen (PSMA) is a receptor on the surface of prostate cancer cells that is revolutionising the way we image and treat men with prostate cancer. New small molecule peptides with high-binding affinity for the PSMA receptor have allowed high quality, highly specific PET imaging, in addition to the development of targeted radionuclide therapy for men with prostate cancer. This targeted therapy for prostate cancer has, to date, predominately used Lutetium 177 (Lu) labelled PSMA peptides. Early clinical studies evaluating the safety and efficacy of Lu PSMA therapy have demonstrated promising results with a significant proportion of men with metastatic prostate cancer, who have already failed other therapies, responding clinically to Lu PSMA. This review discusses the practical issues of administering Lu PSMA, and gives an overview of the findings from currently published trials in regards to treatment response rates, expected toxicities and safety. © 2017 The Authors. Journal of Medical Radiation Sciences published by John Wiley & Sons Australia, Ltd on behalf of Australian Society of Medical Imaging and Radiation Therapy and New Zealand Institute of Medical Radiation Technology.

  17. Electron microscopy studies of lutetium doped erbium silicide (Er{sub 0.9}Lu{sub 0.1}){sub 5}Si{sub 4}

    SciTech Connect

    Cao, Q. Chumbley, L.S.

    2011-08-15

    Examination of bulk microstructures of lutetium doped erbium silicide (Er{sub 0.9}Lu{sub 0.1}){sub 5}Si{sub 4} (space group: Pnma) using scanning and transmission electron microscopy (SEM, TEM) reveals the existence of thin plates of a hexagonal phase (space group: P6{sub 3}/mcm) where the stoichiometric ratio in moles between the rare earths and Si is 5 to 3, i. e the 5:3 phase. The orientation relationship between the matrix and the plates was determined as [010]{sub m} {approx} -parallel [-1010]{sub p.} This observation adds credence to the assumption that all linear features noted in alloys of the rare-earth intermetallic family R{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4} are of the stoichiometric ratio 5:3 and possess a common orientation relationship with the parent 5:4 alloys. - Highlights: {yields} The linear features observed in the (Er{sub 0.9}Lu{sub 0.1}){sub 5}Si{sub 4} sample are hexagonal 5:3 plates. {yields} Thickness of 5:3 plates in 5:4 alloys made by tri-arc pulling is greater than made by arc-melting. {yields} The orientation relationship between 5:3 plates and the matrix is [010]{sub m} {approx} ||[-1010]{sub p}.

  18. Indirect Production of No Carrier Added (NCA) (177)Lu from Irradiation of Enriched (176)Yb: Options for Ytterbium/Lutetium Separation.

    PubMed

    Dash, Ashutosh; Chakravarty, Rubel; Knapp, Furn F Russ; Pillai, Ambikalmajan M R

    2015-01-01

    This article presents a concise review of the production of no-carrier-added (NCA) (177)Lu by the 'indirect' route by irradiating ytterbium-176 ((176)Yb)-enriched targets. The success of this production method depends on the ability to separate the microscopic amounts of NCA (177)Lu from bulk irradiated ytterbium targets. The presence of Yb(+3) from the target in the final processed (177)Lu will adversely affect the quality of (177)Lu by decreasing the specific activity and competing with Lu(+3) complexation since ytterbium will follow the same coordination chemistry. Ytterbium and lutetium are adjacent members of the lanthanide family with very similar chemical properties which makes the separation of one from the other a challenging task. This review provides a summary of the methods developed for the separation and purification of NCA (177)Lu from neutron irradiated (176)Yb-enriched targets, a critical assessment of recent developments and a discussion of the current status of this (177)Lu production method.

  19. 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.

  20. 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.

  1. Combustion front dynamics in the combustion synthesis of refractory metal carbides and di-borides using time-resolved X-ray diffraction.

    PubMed

    Wong, Joe; Larson, E M; Waide, P A; Frahm, R

    2006-07-01

    A compact diffraction-reaction chamber, using a 2-inch photodiode array detector, has been employed to investigate the chemical dynamics at the combustion front of a selected series of refractory metal carbides and di-borides from their constituent element reactants as well as binary products from B4C as a reactant. These systems are denoted as (i) M + C --> MC; (ii) M + 2B --> MB2; and (iii) 3M + B4C --> 2MB2 + MC, where M = Ti, Zr, Nb, Hf or Ta. Time-resolved X-ray diffraction using intense synchrotron radiation at frame rates up to 10 frames s(-1) (or 100 ms frame(-1)) was employed. The combustion reactions were found to complete within 200-400 ms. In contrast to the Ta + C --> TaC combustion system studied earlier, in which a discernible intermediate sub-carbide phase was first formed, reacted further and disappeared to yield the final TaC product, no intermediate sub-carbide or sub-boride was detected in the current systems. Combustion for the Ti, Zr and Hf systems involved a liquid phase, in which the adiabatic temperatures Tad are well above the melting points of the respective reactant metals and have a typical combustion front velocity of 5-6 mm s(-1). The Nb and Ta systems have lower Tad, involving no liquid phase. These are truly solid combustion systems and have a lower combustion front velocity of 1-2 mm s(-1). The current study opens up a new avenue to chemical dynamics and macrokinetic investigations of high-temperature solid-state reactions.

  2. 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 La2Re3B7 and La3Re2B5 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 La2Re3B7 (space group Pcca) having lattice parameters a = 7.657(2) Å, b = 6.755(1) Å, and c = 11.617(2) Å, and La3Re2B5 (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 that are built up from rhenium boride polyhedra and boron-boron bonding. La3Re2B5 featuresmore » fairly common B2 dumbbells, whereas La2Re3B7 has unique one-dimensional subunits composed of alternating triangular B3 and trans-B4 zigzag chain fragments. Also observed in La3Re2B5 is an unusual coordination of B by an octahedron of La atoms. Electronic band structure calculations predict that La2Re3B7 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 La3Re2B5 is a regular metal.« less

  3. Metallic Borides, La2Re3B7 and La3Re2B5, Featuring Extensive Boron-Boron Bonding.

    PubMed

    Bugaris, Daniel E; Malliakas, Christos D; Chung, Duck Young; Kanatzidis, Mercouri G

    2016-02-15

    La2Re3B7 and La3Re2B5 have been synthesized 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 La2Re3B7 (space group Pcca) having lattice parameters a = 7.657(2) Å, b = 6.755(1) Å, and c = 11.617(2) Å, and La3Re2B5 (space group Pmma) having lattice parameters a = 10.809(2) Å, b = 5.287(1) Å, and c = 5.747(1) Å. The compounds possess three-dimensional framework structures that are built up from rhenium boride polyhedra and boron-boron bonding. La3Re2B5 features fairly common B2 dumbbells, whereas La2Re3B7 has unique one-dimensional subunits composed of alternating triangular B3 and trans-B4 zigzag chain fragments. Also observed in La3Re2B5 is an unusual coordination of B by an octahedron of La atoms. Electronic band structure calculations predict that La2Re3B7 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 ρ300 K of ∼375 μΩ cm. The electronic band structure calculations also suggest that La3Re2B5 is a regular metal.

  4. 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.

  5. Lutetium oxyorthosilicate (LSO) intrinsic activity correction and minimal detectable target activity study for SPECT imaging with a LSO-based animal PET scanner

    NASA Astrophysics Data System (ADS)

    Yao, Rutao; Ma, Tianyu; Shao, Yiping

    2008-08-01

    This work is part of a feasibility study to develop SPECT imaging capability on a lutetium oxyorthosilicate (LSO) based animal PET system. The SPECT acquisition was enabled by inserting a collimator assembly inside the detector ring and acquiring data in singles mode. The same LSO detectors were used for both PET and SPECT imaging. The intrinsic radioactivity of 176Lu in the LSO crystals, however, contaminates the SPECT data, and can generate image artifacts and introduce quantification error. The objectives of this study were to evaluate the effectiveness of a LSO background subtraction method, and to estimate the minimal detectable target activity (MDTA) of image object for SPECT imaging. For LSO background correction, the LSO contribution in an image study was estimated based on a pre-measured long LSO background scan and subtracted prior to the image reconstruction. The MDTA was estimated in two ways. The empirical MDTA (eMDTA) was estimated from screening the tomographic images at different activity levels. The calculated MDTA (cMDTA) was estimated from using a formula based on applying a modified Currie equation on an average projection dataset. Two simulated and two experimental phantoms with different object activity distributions and levels were used in this study. The results showed that LSO background adds concentric ring artifacts to the reconstructed image, and the simple subtraction method can effectively remove these artifacts—the effect of the correction was more visible when the object activity level was near or above the eMDTA. For the four phantoms studied, the cMDTA was consistently about five times of the corresponding eMDTA. In summary, we implemented a simple LSO background subtraction method and demonstrated its effectiveness. The projection-based calculation formula yielded MDTA results that closely correlate with that obtained empirically and may have predicative value for imaging applications.

  6. Phase II study of Lutetium-177-labeled anti-prostate-specific membrane antigen monoclonal antibody J591 for metastatic castration-resistant prostate cancer.

    PubMed

    Tagawa, Scott T; Milowsky, Matthew I; Morris, Michael; Vallabhajosula, Shankar; Christos, Paul; Akhtar, Naveed H; Osborne, Joseph; Goldsmith, Stanley J; Larson, Steve; Taskar, Neeta Pandit; Scher, Howard I; Bander, Neil H; Nanus, David M

    2013-09-15

    To assess the efficacy of a single infusion of radiolabeled anti-prostate-specific membrane antigen (PSMA) monoclonal antibody J591 (lutetium-177; (177)Lu) by prostate-specific antigen (PSA) decline, measurable disease response, and survival. In this dual-center phase II study, two cohorts with progressive metastatic castration-resistant prostate cancer received one dose of (177)Lu-J591 (15 patients at 65 mCi/m(2), 17 at 70 mCi/m(2)) with radionuclide imaging. Expansion cohort (n = 15) received 70 mCi/m(2) to verify response rate and examine biomarkers. Forty-seven patients who progressed after hormonal therapies (55.3% also received prior chemotherapy) received (177)Lu-J591. A total of 10.6% experienced ≥50% decline in PSA, 36.2% experienced ≥30% decline, and 59.6% experienced any PSA decline following their single treatment. One of 12 with measurable disease experienced a partial radiographic response (8 with stable disease). Sites of prostate cancer metastases were targeted in 44 of 47 (93.6%) as determined by planar imaging. All experienced reversible hematologic toxicity, with grade 4 thrombocytopenia occurring in 46.8% (29.8% received platelet transfusions) without significant hemorrhage. A total of 25.5% experienced grade 4 neutropenia, with one episode of febrile neutropenia. The phase I maximum tolerated dose (70 mCi/m(2)) resulted in more 30% PSA declines (46.9% vs. 13.3%, P = 0.048) and longer survival (21.8 vs. 11.9 months, P = 0.03), but also more grade 4 hematologic toxicity and platelet transfusions. No serious nonhematologic toxicity occurred. Those with poor PSMA imaging were less likely to respond. A single dose of (177)Lu-J591 was well tolerated with reversible myelosuppression. Accurate tumor targeting and PSA responses were seen with evidence of dose response. Imaging biomarkers seem promising. ©2013 AACR.

  7. Is there need for radioimmunotherapy? results of a phase I/II study in patients with indolent B-cell lymphomas using lutetium-177-DOTA-rituximab.

    PubMed

    Forrer, F; Oechslin-Oberholzer, C; Campana, B; Maecke, H; Mueller-Brand, J; Lohri, A

    2012-12-01

    The aim of the study was to explore the clinical response to 177Lutetium-DOTA-rituximab (177Lu-D-R) and to determine the maximum tolerated dose (MTD) in the treatment of patients with relapsed follicular, mantle cell or other indolent lymphomas such as marginal zone lymphoma as well as to put these results into context with other therapy options for these patients. Treatment consisted of cold rituximab (250 mg/m2) on day 1 and day 8 and 177Lu-DOTA-Rituximab on day 8. Reassessment was done at week 10. Thirty-one patients (males=17, females=14, median number of pretreatments: 3) were treated in seven cohorts. Escalation of injected activity was carried out in steps of 5 mCi/m². Dosimetry was performed in the first 20 patients. The MTD was found to be 45 mCi/m2. Thrombocytopenia and leukopenia were the dose-limiting toxicities. Significant anemia only occurred at dose level 7. We observed the nadir of platelets after a median of 36 days from treatment with 177Lu-D-R and a nadir of granulocytes after a median of 50 days from 177Lu-D-R treatment. Non-hematological toxicity was negligible. We observed clinical responses at all dose levels and for all lymphoma entities. Some of the responses were durable; the longest follow up in complete remission is currently over eight years. The MTD of 177Lu-DOTA-Rituximab was found to be 45 mCi/m². Non hematologic toxicity was negligible. Responses were seen in all lymphoma entities and at all dose levels tested. Further testing seems to be most promising mainly in follicular and marginal zone lymphoma in particular as the results compare well to other therapy options for these patients with regard to effectiveness, toxicity and discomfort for the patients.

  8. Lutetium oxyorthosilicate (LSO) intrinsic activity correction and minimal detectable target activity study for SPECT imaging with a LSO-based animal PET scanner.

    PubMed

    Yao, Rutao; Ma, Tianyu; Shao, Yiping

    2008-08-21

    This work is part of a feasibility study to develop SPECT imaging capability on a lutetium oxyorthosilicate (LSO) based animal PET system. The SPECT acquisition was enabled by inserting a collimator assembly inside the detector ring and acquiring data in singles mode. The same LSO detectors were used for both PET and SPECT imaging. The intrinsic radioactivity of (176)Lu in the LSO crystals, however, contaminates the SPECT data, and can generate image artifacts and introduce quantification error. The objectives of this study were to evaluate the effectiveness of a LSO background subtraction method, and to estimate the minimal detectable target activity (MDTA) of image object for SPECT imaging. For LSO background correction, the LSO contribution in an image study was estimated based on a pre-measured long LSO background scan and subtracted prior to the image reconstruction. The MDTA was estimated in two ways. The empirical MDTA (eMDTA) was estimated from screening the tomographic images at different activity levels. The calculated MDTA (cMDTA) was estimated from using a formula based on applying a modified Currie equation on an average projection dataset. Two simulated and two experimental phantoms with different object activity distributions and levels were used in this study. The results showed that LSO background adds concentric ring artifacts to the reconstructed image, and the simple subtraction method can effectively remove these artifacts-the effect of the correction was more visible when the object activity level was near or above the eMDTA. For the four phantoms studied, the cMDTA was consistently about five times of the corresponding eMDTA. In summary, we implemented a simple LSO background subtraction method and demonstrated its effectiveness. The projection-based calculation formula yielded MDTA results that closely correlate with that obtained empirically and may have predicative value for imaging applications.

  9. Keggin polyoxoanion supported organic-inorganic trinuclear lutetium cluster, {Na(H2O)3[Lu(pydc)(H2O)3]3}[SiW12O40]·26.5H2O.

    PubMed

    Li, Suzhi; Zhang, Dongdi; Guo, Yuan Yuan; Ma, Pengtao; Qiu, Xiaoyang; Wang, Jingping; Niu, Jingyang

    2012-09-07

    A novel strawberry-like organic-inorganic hybrid, {Na(H(2)O)(3)[Lu(pydc)(H(2)O)(3)](3)}[SiW(12)O(40)]·26.5H(2)O (H(2)pydc = pyridine-2,6-dicarboxylate) containing an intriguing trinuclear lutetium cluster {Na(H(2)O)(3)[Lu(pydc)(H(2)O)(3)](3)}(4+) has been synthesized and its luminescent properties, IR, UV, TG, PXRD analyses and single crystal X-ray diffraction were investigated.

  10. The electronic structure, mechanical and thermodynamic properties of Mo{sub 2}XB{sub 2} and MoX{sub 2}B{sub 4} (X = Fe, Co, Ni) ternary borides

    SciTech Connect

    He, TianWei; Jiang, YeHua E-mail: jfeng@seas.harvard.edu; Zhou, Rong; Feng, Jing E-mail: jfeng@seas.harvard.edu

    2015-08-21

    The mechanical properties, electronic structure and thermodynamic properties of the Mo{sub 2}XB{sub 2} and MoX{sub 2}B{sub 4} (X = Fe, Co, Ni) ternary borides were calculated by first-principles methods. The elastic constants show that these ternary borides are mechanically stable. Formation enthalpy of Mo{sub 2}XB{sub 2} and MoX{sub 2}B{sub 4} (X = Fe, Co, Ni) ternary borides are at the range of −118.09 kJ/mol to −40.14 kJ/mol. The electronic structures and chemical bonding characteristics are analyzed by the density of states. Mo{sub 2}FeB{sub 2} has the largest shear and Young's modulus because of its strong chemical bonding, and the values are 204.3 GPa and 500.3 GPa, respectively. MoCo{sub 2}B{sub 4} shows the lowest degree of anisotropy due to the lack of strong direction in the bonding. The Debye temperature of MoFe{sub 2}B{sub 4} is the largest among the six phases, which means that MoFe{sub 2}B{sub 4} possesses the best thermal conductivity. Enthalpy shows an approximately linear function of the temperature above 300 K. The entropy of these compounds increase rapidly when the temperature is below 450 K. The Gibbs free energy decreases with the increase in temperature. MoCo{sub 2}B{sub 4} has the lowest Gibbs free energy, which indicates the strongest formation ability in Mo{sub 2}XB{sub 2} and MoX{sub 2}B{sub 4} (X = Fe, Co, Ni) ternary borides.

  11. Phase 1 radioimmunotherapy study with lutetium 177-labeled anti-carbonic anhydrase IX monoclonal antibody girentuximab in patients with advanced renal cell carcinoma.

    PubMed

    Stillebroer, Alexander B; Boerman, Otto C; Desar, Ingrid M E; Boers-Sonderen, Marije J; van Herpen, Carla M L; Langenhuijsen, Johannes F; Smith-Jones, Peter M; Oosterwijk, Egbert; Oyen, Wim J G; Mulders, Peter F A

    2013-09-01

    Patients with metastatic clear cell renal cell carcinoma (ccRCC) have a dismal prognosis. Therefore, new and less toxic treatments are needed. We determined the maximum tolerated dose (MTD) and potential therapeutic efficacy of multiple infusions of lutetium 177 ((177)Lu)-girentuximab (cG250) on various dose levels in a phase 1 trial in patients with progressive metastasized ccRCC. In this uncontrolled case series in 23 patients with progressive ccRCC metastases, cG250 accumulation was verified by diagnostic indium 111-cG250 imaging. Patients then received a high-activity dose of (177)Lu-cG250. Groups of three patients received (177)Lu-cG250, starting at a dose level of 1110 MBq/m(2)(177)Lu-cG250, with dose increments of 370 MBq/m(2) per group. In the absence of persistent toxicity, progressive disease, and accelerated blood clearance, patients were eligible for retreatment after 3 mo with 75% of the previous activity dose. Patients could receive a total of three treatment cycles. Determination of the MTD was the primary and therapeutic efficacy was the secondary outcome measurement of the study. The MTD was 2405 MBq/m(2) because higher doses resulted in dose-limiting myelotoxicity. Some patients received second (13 of 23 [56%]) and third (4 of 23 [17%]) treatment cycles. Most patients (17 of 23 [74%]) demonstrated stable disease 3 mo after the first treatment, and one patient showed a partial response that lasted for 9 mo. Mean growth of target tumor lesions was reduced from 40.4% (95% confidence interval [CI], ± 17.0) during the last 3 mo before study entry to 5.5% (95% CI, ± 5.3; p<0.001) at 3 mo after the first treatment cycle. No major nonhematologic side effects were observed. (177)Lu-cG250 radioimmunotherapy in metastatic ccRCC patients is well tolerated at an activity dose level as high as 2405 MBq/m(2) (MTD). Radioimmunotherapy with (177)Lu-cG250 may stabilize previously progressive metastatic ccRCC. Copyright © 2012 European Association of Urology

  12. Novel double-layer titanium boride coating on CP-titanium and titanium-aluminum-vanadium alloy: Kinetics of boron diffusion and coating morphologies

    NASA Astrophysics Data System (ADS)

    Tikekar, Nishant M.

    2007-12-01

    Commercially pure titanium (CP-Ti) and its alloy, Ti-6Al-4V, have found widespread use in aerospace, mechanical and biomedical industries due to their high strength to weight ratio, high stiffness, excellent corrosion resistance and biocompatibility. Although these materials provide significant engineering performance, problems such as galling, seizing and poor wear resistance have limited their use. One way of achieving increased wear performance is by modifying their surface properties by deposition of a suitable coating via solid-state diffusion. Hence, this research has been undertaken with the objective of developing a powder-based process for depositing a thick double-layer boride (TiB2 + TiB) coating on Ti-6Al-4V and CP-Ti and a simple solid-state diffusion model to predict the growth kinetics of TiB2 and TiB layers of the coating, based on processing parameters. The powder composition that resulted in maximum double-layer thickness with clean surface finish was found to be: Composition A (where, A = powder mixture of boron source, transport medium and scavenger). Boriding experiments were conducted in the temperature range 950-1200°C on Ti-6Al-4V and 850-1050°C on CP-Ti samples for time periods studied ranging from 3 to 24 hours at different temperatures. The growth kinetics of TiB2 and total (TiB2 + TiB) layers seem to be parabolic. The layer growth kinetics of TiB was found to be nonparabolic. TiB whiskers had different morphologies at temperatures above and below the beta-transus temperatures of Ti-6Al-4V and CP-Ti. For both materials, typically, TiB whiskers were thin below the beta-transus temperature and thicker above it. The theoretical model seems to show good agreement with the experimental data of TiB2 thicknesses on CP-Ti at all the temperatures studied. For total (TiB2 + TiB) coating thicknesses, the model showed good agreement with experimental data at all temperatures, except 1050°C. In case of Ti-6Al-4V, the model showed good agreement

  13. Stability and crystal chemistry of the ternary borides M2(Ni21-xMx)B6 (M tbnd Ti, Zr, Hf)

    NASA Astrophysics Data System (ADS)

    Artini, C.; Provino, A.; Valenza, F.; Pani, M.; Cacciamani, G.

    2016-01-01

    A crystallochemical study was undertaken to investigate the structural stability and the compositional extent of the ternary borides M2(Ni21-xMx)B6 (M tbnd Ti, Zr, Hf). This phase often occurs during the production of MB2 joints by means of Ni-B brazing alloys. Samples with the nominal compositions M2Ni21B6 and M3Ni20B6 were synthesized by arc melting and characterized by optical and electron microscopy, and X-ray diffraction. Crystal structure refinements were performed by the Rietveld method. The compositional boundaries of the ternary phases were experimentally determined and found strictly related to the M/Ni size ratio. The stability of this structure is mainly determined by the capability of the structure to expand under the effect of the Ni substitution by the M atom. The CALPHAD modeling of the three M-Ni-B ternary systems in the Ni-rich corner of the phase diagram, performed on the basis of the obtained structural data, shows a good agreement with experimental results.

  14. Microstructural Characterization and Wear Behavior of Nano-Boride Dispersed Coating on AISI 304 Stainless Steel by Hybrid High Velocity Oxy-Fuel Spraying Laser Surface Melting

    NASA Astrophysics Data System (ADS)

    Sharma, Prashant; Majumdar, Jyotsna Dutta

    2015-07-01

    The current study concerns the detailed microstructural characterization and investigation of wear behavior of nano-boride dispersed coating developed on AISI 304 stainless steel by high velocity oxy-fuel spray deposition of nickel-based alloy and subsequent laser melting. There is a significant refinement and homogenization of microstructure with improvement in microhardness due to laser surface melting (1200 VHN as compared to 945 VHN of as-sprayed and 250 VHN of as-received substrate). The high temperature phase stability of the as-coated and laser melted surface has been studied by differential scanning calorimeter followed by detailed phase analysis at room and elevated temperature. There is a significant improvement in wear resistance of laser melted surface as compared to as-sprayed and the as-received one due to increased hardness and reduced coefficient of friction. The mechanism of wear has been investigated in details. Corrosion resistance of the coating in a 3.56 wt pct NaCl solution is significantly improved (4.43 E-2 mm/year as compared to 5 E-1 mm/year of as-sprayed and 1.66 mm/year of as-received substrate) due to laser surface melting as compared to as-sprayed surface.

  15. 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.

  16. 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

    SciTech Connect

    Bykova, E.; Gou, H.; Bykov, M.; Hanfland, M.; Dubrovinsky, L.; Dubrovinskaia, N.

    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 high 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.

  17. 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)

  18. 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.

  19. Ternary borides Nb7Fe3B8 and Ta7Fe3B8 with Kagome-type iron framework.

    PubMed

    Zheng, Qiang; Gumeniuk, Roman; Borrmann, Horst; Schnelle, Walter; Tsirlin, Alexander A; Rosner, Helge; Burkhardt, Ulrich; Reissner, Michael; Grin, Yuri; Leithe-Jasper, Andreas

    2016-06-21

    Two new ternary borides TM7Fe3B8 (TM = Nb, Ta) were synthesized by high-temperature thermal treatment of samples obtained by arc-melting. This new type of structure with space group P6/mmm, comprises TM slabs containing isolated planar hexagonal [B6] rings and iron centered TM columns in a Kagome type of arrangement. Chemical bonding analysis in Nb7Fe3B8 by means of the electron localizability approach reveals two-center interactions forming the Kagome net of Fe and embedded B, while weaker multicenter bonding present between this net and Nb atoms. Magnetic susceptibility measurements reveal antiferromagnetic order below TN = 240 K for Nb7Fe3B8 and TN = 265 K for Ta7Fe3B8. Small remnant magnetization below 0.01μB per f.u. is observed in the antiferromagnetic state. The bulk nature of the magnetic transistions was confirmed by the hyperfine splitting of the Mössbauer spectra, the sizable anomalies in the specific heat capacity, and the kinks in the resistivity curves. The high-field paramagnetic susceptibilities fitted by the Curie-Weiss law show effective paramagnetic moments μeff≈ 3.1μB/Fe in both compounds. The temperature dependence of the electrical resistivity also reveals metallic character of both compounds. Density functional calculations corroborate the metallic behaviour of both compounds and demonstrate the formation of a sizable local magnetic moment on the Fe-sites. They indicate the presence of both antiferro- and ferrromagnetic interactions.

  20. ScRu2B3 and Sc2RuB6: Borides Featuring a 2D Infinite Boron Clustering.

    PubMed

    Salamakha, Leonid P; Sologub, Oksana; Stöger, Berthold; Rogl, Peter Franz; Waas, Monika; Kapustianyk, Volodymyr B; Bauer, Ernst

    2017-09-05

    Two borides, ScRu2B3 and Sc2RuB6, were obtained by argon-arc melting of the elements followed by annealing at 800 °C. ScRu2B3 exhibits a new structure type with the space group Cmcm (a = 3.0195(2) Å, b = 15.4056(8) Å, c = 5.4492(3) Å; single crystal X-ray data; RF(2) = 0.0105). Sc2RuB6 adopts the Y2ReB6-type structure (space group Pbam; a = 8.8545(2) Å, b = 11.1620(3) Å, c = 3.4760(1) Å; single crystal X-ray data; RF(2) = 0.0185). ScRu2B3 displays an unusual intergrowth of CeCo3B2- and AlB2-related slabs; a striking feature is a boat configuration of puckered boron hexagons within infinite graphite like boron layers (6(3) nets). Sc2RuB6 presents two-dimensional planar nets of condensed boron pentagons, hexagons, and heptagons sandwiched between metal layers. In Sc/Y substituted Y2ReB6-type, Y atoms are distributed exclusively inside the boron heptagons. Exploration of the Sc-Ru-B system at 800 °C including binary boundaries employing EPMA and powder X-ray diffraction technique furthermore rules out the existence of previously reported "ScRuB4" but confirms the formation and crystal structure of Sc2Ru5B4. ScRu4B4 forms in cast alloys (LuRu4B4-type structure; space group I41/acd (No. 142), a = 7.3543(2) Å, c = 14.92137(8) Å). Cell parameters and atomic coordinates have been refined for ScRu2B3, Sc2RuB6, and ScRu4B4 in the scope of the generalized gradient approximation. Ab initio electronic structure calculations indicate a moderate electronic density of states at the Fermi level situated near the upper edge of essentially filled d-bands. Electrical resistivity measurements characterize ScRu2B3 and Sc2RuB6 as metals in concord with electronic band structure calculations.

  1. Th7 Fe3 -Type Related Structures in Pd(Pt)-Cu-B Systems: Pd6 CuB3 -A New Structure Type for Borides.

    PubMed

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

    2017-04-06

    A new member of the series of Th7 Fe3 -type derivative structures, h-(Pd0.86 Cu0.14 )7 B3 (≡Pd6.02 Cu0.98 B3 , unique structure type Pd6 CuB3 , space group P63 cm, a=12.9426(9) Å, c=4.8697(4) Å, single-crystal X-ray diffraction (XRD) data) was obtained from as cast alloys and alloys annealed at 600-650 °C. Further substitution of Cu by Pd led to formation of a Mn7 C3 -type structure, o-(Pd0.93 Cu0.07 )7 B3 (≡Pd6.51 Cu0.49 B3 , space group Pnma, a=4.8971(2) Å, b=7.5353(3) Å, c=12.9743(6) Å, single-crystal XRD). Isotypic LT h-(Pt0.70 Cu0.30 )7 B3 (≡Pt4.90 Cu2.10 B3 ) was observed in the Pt-Cu-B system as a low-temperature (LT) phase (T≤600 °C) (powder XRD), whereas the Th7 Fe3 -type (high-temperature (HT) h-(Pt0.73 Cu0.27 )7 B3 ≡Pt5.11 Cu1.89 B3 , space group P63 mc, a=7.4671(1) Å, c=4.9039(1) Å, powder XRD) proved to be stable at high temperature. The three structures are built of columns of face connected metal octahedra and columns of metal tetrahedra alternatingly fused by common faces and vertices. Boron atoms are found in trigonal prisms formed by metal atoms. The volumes of the three new Th7 Fe3 -type derivative borides relate as 1:2:3. Superconductivity was discovered for Pt4.9 Cu2.1 B3 (Pd6 CuB3 -type) and Pt5.1 Cu1.9 B3 (Th7 Fe3 -type) below 0.67 and 0.66 K, respectively. Despite the close value of the transition temperature the values of the upper critical field at 0 K differ as 0.37 T and 0.27 T for the two compounds. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. 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.

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

    SciTech Connect

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

    2016-01-26

    We synthesized La2Re3B7 and La3Re2B5 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 La2Re3B7 (space group Pcca) having lattice parameters a = 7.657(2) Å, b = 6.755(1) Å, and c = 11.617(2) Å, and La3Re2B5 (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 that are built up from rhenium boride polyhedra and boron-boron bonding. La3Re2B5 features fairly common B2 dumbbells, whereas La2Re3B7 has unique one-dimensional subunits composed of alternating triangular B3 and trans-B4 zigzag chain fragments. Also observed in La3Re2B5 is an unusual coordination of B by an octahedron of La atoms. Electronic band structure calculations predict that La2Re3B7 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 La3Re2B5 is a regular metal.

  4. Performance characteristics obtained for a new 3-dimensional lutetium oxyorthosilicate-based whole-body PET/CT scanner with the National Electrical Manufacturers Association NU 2-2001 standard.

    PubMed

    Brambilla, Marco; Secco, Chiara; Dominietto, Marco; Matheoud, Roberta; Sacchetti, Gianmauro; Inglese, Eugenio

    2005-12-01

    This article reports the results of performance measurements obtained for the lutetium oxyorthosilicate (LSO)-based whole-body PET/CT scanner Biograph 16 HI-REZ with the National Electrical Manufacturers Association (NEMA) NU 2-2001 standard. The Biograph 16 HI-REZ combines a multislice (16-slice) spiral CT scanner with a PET scanner composed of 24.336 LSO crystals arranged in 39 rings. The crystal dimensions are 4.0x4.0x20 mm3, and the crystals are organized in 13x13 blocks coupled to 4 photomultiplier tubes each. The 39 rings allow the acquisition of 81 images 2.0 mm thick, covering an axial field of view of 162 mm. The low- and high-energy thresholds are set to 425 and 650 keV, respectively, acquiring data within a 4.5-ns-wide coincidence window. Performance measurements for the LSO-based PET/CT scanner were obtained with the NEMA NU 2-2001 standard, taking into account issues deriving from the presence of intrinsic radiation. The results obtained with the NEMA NU 2-2001 standard measurements were as follows: average transverse and axial spatial resolutions (full width at half maximum) at 1 cm and at 10 cm off axis of 4.61 (5.10) mm and 5.34 (5.91) mm, respectively; average sensitivity of 4.92 counts per second per kilobecquerel for the 2 radial positions (0 and 10 cm); 34.1% system scatter fraction; and peak noise equivalent count (NEC) rates of 84.77 kilocounts per second (kcps) at 28.73 kBq/mL (k=1 in the NEC formula; noiseless random correction) and 58.71 kcps at 21.62 kBq/mL (k=2; noisy random correction). The new integrated PET/CT system Biograph 16 HI-REZ has good overall performance, with, in particular, a high resolution, a low scatter fraction, and a very good NEC response.

  5. Lutetium-177-labelled anti-prostate-specific membrane antigen antibody and ligands for the treatment of metastatic castrate-resistant prostate cancer: a systematic review and meta-analysis.

    PubMed

    Calopedos, R J S; Chalasani, V; Asher, R; Emmett, L; Woo, H H

    2017-09-01

    Promising therapeutic results of the prostate-specific membrane antigen (PSMA) ligand have been shown when labelling with lutetium-177 ((177)Lu). We performed a systematic review and meta-analysis to assess the therapeutic response of (177)Lu-PSMA in the treatment of metastatic castration-resistant prostate cancer (mCRPC). A systematic review was conducted using electronic databases up to December 2016. Two reviewers independently extracted data and assessed methodological quality. The main outcome of interest was antitumour biochemical response of (177)Lu-PSMA, analysing two measures: 'any PSA decline' and '>50% decline' from baseline. A random-effects meta-analysis was used to calculate the pooled proportion across studies. The I(2) statistic was calculated in each case to investigate the extent of heterogeneity across the studies. A sensitivity analysis was conducted removing two studies, which were presented as abstracts and proportions were summarised by chemical type ((177)Lu-J591/DKZ/I&T). All analyses were conducted using Stata v14. A total of 10 studies were included in the analysis giving a total sample size of 369, 220 (of 334 analysable) experienced any PSA decline. The pooled proportion of patients with any PSA decline was 68% (95% confidence interval (CI): 61-74). The I(2) statistic was 39.1% (P=0.11) suggesting minor heterogeneity between results. The pooled proportion of patients with >50% PSA decline was 37% (95% CI: 22-52). The I(2) statistic was 91.0% (P<0.001) suggesting substantial heterogeneity between results. On subgroup analysis, a higher proportion of patients in the (177)Lu-DKZ/I&T subgroup had a PSA decline >50%, however, it can be seen that the (177)Lu-DKZ/I&T subgroup had a substantial amount of heterogeneity across studies. This review suggests promising early results for the treatment of mCRPC, especially from patients treated with the more recently developed radioligands. Overall, our meta-analysis showed that approximately two

  6. Synthesis and evaluation of bombesin derivatives on the basis of pan-bombesin peptides labeled with indium-111, lutetium-177, and yttrium-90 for targeting bombesin receptor-expressing tumors.

    PubMed

    Zhang, Hanwen; Chen, Jianhua; Waldherr, Christian; Hinni, Karin; Waser, Beatrice; Reubi, Jean Claude; Maecke, Helmut R

    2004-09-15

    Bombesin receptors are overexpressed on a variety of human tumors like prostate, breast, and lung cancer. The aim of this study was to develop radiolabeled (Indium-111, Lutetium-177, and Yttrium-90) bombesin analogues with affinity to the three bombesin receptor subtypes for targeted radiotherapy. The following structures were synthesized: diethylenetriaminepentaacetic acid-gamma-aminobutyric acid-[D-Tyr6, beta-Ala11, Thi13, Nle14] bombesin (6-14) (BZH1) and 1,4,7,10-tetraazacyclododecane-N,N',N",N"' -tetraacetic acid-gamma-aminobutyric acid-[D-Tyr6, beta-Ala11, Thi13, Nle14] bombesin (6-14) (BZH2). [111In]-BZH1 and in particular [90Y]-BZH2 were shown to have high affinity to all three human bombesin receptor subtypes with binding affinities in the nanomolar range. In human serum metabolic cleavage was found between beta-Ala11 and His12 with an approximate half-life of 2 hours. The metabolic breakdown was inhibited by EDTA and beta-Ala11-His12 (carnosine) indicating that carnosinase is the active enzyme. Both 111In-labeled peptides were shown to internalize into gastrin-releasing peptide-receptor-positive AR4-2J and PC-3 cells with similar high rates, which were independent of the radiometal. The biodistribution studies of [111In]-BZH1 and [111In]-BZH2 ([177Lu]-BZH2) in AR4-2J tumor-bearing rats showed specific and high uptake in gastrin-releasing peptide-receptor-positive organs and in the AR4-2J tumor. A fast clearance from blood and all of the nontarget organs except the kidneys was found. These radiopeptides were composed of the first pan-bombesin radioligands, which show great promise for the early diagnosis of tumors bearing not only gastrin-releasing peptide-receptors but also the other two bombesin receptor subtypes and may be of use in targeted radiotherapy of these tumors.

  7. Thermal conductivity of layered borides: The effect of building defects on the thermal conductivity of TmAlB{sub 4} and the anisotropic thermal conductivity of AlB{sub 2}

    SciTech Connect

    Wang, X. J. E-mail: xwang58@illinois.edu; Mori, T. E-mail: xwang58@illinois.edu; Kuzmych-Ianchuk, I.; Michiue, Y.; Yubuta, K.; Shishido, T.; Grin, Y.; Okada, S.; Cahill, D. G.

    2014-04-01

    Rare earth metal borides have attracted great interest due to their unusual properties, such as superconductivity and f-electron magnetism. A recent discovery attributes the tunability of magnetism in rare earth aluminoborides to the effect of so-called “building defects.” In this paper, we report data for the effect of building defects on the thermal conductivities of α-TmAlB{sub 4} single crystals. Building defects reduce the thermal conductivity of α-TmAlB{sub 4} by ≈30%. At room temperature, the thermal conductivity of AlB{sub 2} is nearly a factor of 5 higher than that of α-TmAlB{sub 4}. AlB{sub 2} single crystals are thermally anisotropic with the c-axis thermal conductivity nearly twice the thermal conductivity of the a-b plane. Temperature dependence of the thermal conductivity near and above room temperature reveals that both electrons and phonons contribute substantially to thermal transport in AlB{sub 2} with electrons being the dominant heat carriers.

  8. Rational synthetic tuning between itinerant antiferromagnetism and ferromagnetism in the complex boride series Sc2FeRu(5-n)RhnB2 (0

    PubMed

    Fokwa, Boniface P T; Lueken, Heiko; Dronskowski, Richard

    2007-01-01

    Single crystals of the complex boride series Sc(2)FeRu(5-n)Rh(n)B(2) (n=1, 3, 4) were synthesized by arc-melting the elements in water-cooled copper crucibles under argon atmospheres and were chemically characterized by single-crystal XRD and EDX analyses. The new compounds are isotypic and crystallize in the tetragonal space group P4/mbm with Z=2, adopting a substitutional variant of the Ti(3)Co(5)B(2)-type structure. The magnetically active iron atoms are arranged in chains with intra- and interchain distances of about 3.02 and 6.60 A, respectively. Strong ferromagnetic interactions are observed for both Sc(2)FeRuRh(4)B(2) (64 valence electrons (VE), TC approximately 350 K, mu(a)=3.1 mu(B)) and Sc(2)FeRu(2)Rh(3)B(2) (63 VE, T(C) approximately 300 K, mu(a)=3.0 mu(B)), whereas antiferromagnetic interactions are found in the case of Sc(2)FeRu(4)RhB(2) (61 VE, T(N) approximately 10 K, mu(eff)=3.2): The magnetism of the entire Sc(2)FeRu(5-n)Rh(n)B(2) (0

  9. Crystal Growth, Structures, and Properties of the Complex Borides, LaOs 2 Al 2 B and La 2 Os 2 AlB 2

    SciTech Connect

    Bugaris, Daniel E.; Han, Fei; Im, Jino; Chung, Duck Young; Freeman, Arthur J.; Kanatzidis, Mercouri G.

    2015-08-17

    Single crystals of two novel quaternary metal borides, LaOs2Al2B and La2Os2AlB2, have been grown from La/Ni eutectic fluxes. LaOs2Al2B crystallizes in tetragonal space group P4/mmm with the CeCr2Si2C-type structure, and lattice parameters a = 4.2075(6) angstrom and c = 5.634(1) angstrom. La2Os2AlB2 exhibits a new crystal structure in monoclinic space group C2/c with lattice parameters a = 16.629(3) angstrom, b = 6.048(1) angstrom, c = 10.393(2) angstrom, and beta = 113.96(3)degrees. Both structures are three-dimensional frameworks with unusual coordination (for solid-state compounds) of the boron atoms by transition metal atoms. The boron atom is square planar in LaOs2Al2B, whereas it exhibits linear and T-shaped geometries in La2Os2AlB2. Electrical resistivity measurements reveal poor metal behavior (rho(30)0 (K) similar to 900 mu Omega cm) for La2Os2AlB2, consistent with the electronic band structure calculations, which also predict a metallic character for LaOs2Al2B.

  10. Mass Analyzed Threshold Ionization of Lutetium Dimer

    NASA Astrophysics Data System (ADS)

    Wu, Lu; Roudjane, Mourad; Liu, Yang; Yang, Dong-Sheng

    2013-06-01

    Lu_2 is produced in a pulsed laser-vaporization metal-cluster source and studied by mass-analyzed threshold ionization (MATI) spectroscopy. The MATI spectrum displays several long progressions from the transitions between various vibrational levels of the neutral and ion electronic states. From the spectrum, the upper limit of the ionization energy of the dimer is determined to be 43996 cm^{-1}, and the vibrational frequencies are measured to be 121 cm^{-1} in the neutral state and 90 cm^{-1} in the ion state. By combining with ab initio calculations at CASPT2 level, the ground state of Lu_2 is identified as ^3Σ_g^-. The ^3Σ_g^- state has an electron configuration of 6sσ_g^25dπ_u^15dπ_u^16sσ_u^2, which is formed by the interactions of two Lu atoms in the ^2D(5d6s^2) ground state. Ionization of the neutral state removes a 5dπ_u bonding electron and yields a ion state with a considerably longer bond distance. Lu_2 has a very different bonding feature from La_2, for which a ^1Σ_g^+ ground state was previously identified with an electron configuration of 5dπ_u^46sσ_g^2 formed by the interactions of two La atoms in the ^4F(5d^26s) excited state. Yang Liu, Lu Wu, Chang-Hua Zhang, Serge A. Krasnokutski, and Dong-Sheng Yang, J. Chem. Phys. 135, 034309 (2011).

  11. Electronic, structural and magnetic studies of niobium borides of group 8 transition metals, Nb{sub 2}MB{sub 2} (M=Fe, Ru, Os) from first principles calculations

    SciTech Connect

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

    2014-03-15

    The Nb{sub 2}FeB{sub 2} phase (U{sub 3}Si{sub 2}-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 Nb{sub 2}OsB{sub 2} (space group P4/mnc, no. 128, a twofold superstructure of U{sub 3}Si{sub 2}-type) with distorted Nb-layers and Os{sub 2}-dumbbells was recently achieved, “Nb{sub 2}RuB{sub 2}” 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 Nb{sub 2}FeB{sub 2} and Nb{sub 2}OsB{sub 2}, but also predict “Nb{sub 2}RuB{sub 2}” to crystalize with the Nb{sub 2}OsB{sub 2} 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 Nb{sub 2}FeB{sub 2}, originating from ferromagnetic interactions within iron chains and antiferromagnetic exchange interactions between them. -- Graphical abstract: Nb{sub 2}FeB{sub 2} (U{sub 3}Si{sub 2} structure type, space group P4/mbm, no. 127) is predicted to order antiferromagnetically, due to the presence of iron chains which show ferromagnetic interactions in the chains and antiferromagnetic interactions between them. “Nb{sub 2}RuB{sub 2}” is predicted to crystallize with the recently discovered Nb{sub 2}OsB{sub 2} twofold superstructure (space group P4/mnc, no. 128) of U{sub 3}Si{sub 2} structure type. The building of ruthenium dumbbells instead of chains along [001] is found to be

  12. Electronic pseudogap-driven formation of new double-perovskite-like borides within the Sc2Ir6-xTxB (T = Pd, Ni; x = 0-6) series.

    PubMed

    Hermus, Martin; Scheifers, Jan P; Touzani, Rachid; Fokwa, Boniface P T

    2015-04-20

    Analysis of the electronic density of states of the hypothetical ternary double-perovskite-like phases "Sc2T6B (T = Ir, Pd, Ni)" reveals the presence of deep and large pseudogaps between 61 and 68 valence electrons (VE) as well as a strong peak at 69 VEs. Subsequently, crystal orbital Hamilton population (COHP) bonding analysis shows that the heteroatomic T-B and Sc-T interactions are optimized in Sc2Ir6B (63 VE) but not in "Sc2Pd6B (69 VE)" and "Sc2Ni6B (69 VE)", thus indicating less stability for these VE-richer phases. These findings point out the possibility of discovering new double-perovskite-like borides through chemical substitution and lead to the study of the Sc2Ir6-xPdxB and Sc2Ir6-xNixB (x = 0-6; VE = 63-69) series, for which powder samples and single crystals were synthesized by arc melting the elements. Superstructure reflections were observed in the powder diffractograms of Sc2Ir6-xPdxB and Sc2Ir6-xNixB for x = 0-5 and VE = 63-68, thereby showing that these phases crystallize in the double-perovskite-like Ti2Rh6B-type structure (space group Fm3̅m, Z = 4). Single-crystal and Rietveld refinement results confirm and extend these findings because Pd (or Ni) is found to mix exclusively with Ir in all quaternary compositions. For x = 6, no superstructure reflections were observed, in accordance with the theoretical expectation for the 69 VE phases.

  13. In{sub 3}Ir{sub 3}B, In{sub 3}Rh{sub 3}B and In{sub 5}Ir{sub 9}B{sub 4}, the first indium platinum metal borides

    SciTech Connect

    Kluenter, Wilhelm; Jung, Walter . E-mail: walter.jung@uni-koeln.de

    2006-09-15

    The first indium platinum metal borides have been synthesized and structurally characterized by single crystal X-ray diffraction data. In{sub 3}Ir{sub 3}B and In{sub 3}Rh{sub 3}B are isotypic. They crystallize with the hexagonal space group P6-bar 2m and Z=1. The lattice constants are a=685.78(1)pm, c=287.30(1)pm for In{sub 3}Ir{sub 3}B and a=678.47(3)pm, c=288.61(6)pm for In{sub 3}Rh{sub 3}B. The structure which is derived from the Fe{sub 2}P type is characterized by columns of boron centered triangular platinum metal prisms inserted in a three-dimensional indium matrix. The indium atoms are on split positions. In{sub 5}Ir{sub 9}B{sub 4} (hexagonal, space group P6-bar 2m, a=559.0(2)pm, c=1032.6(3)pm, Z=1) crystallizes with a structure derived from the CeCo{sub 3}B{sub 2} type. The structure can be interpreted as a layer as well as a channel structure. In part the indium atoms are arranged at the vertices of a honeycomb net (Schlaefli symbol 6{sup 3}) separating slabs consisting of double layers of triangular Ir{sub 6}B prisms, and in part they form a linear chain in a hexagonal channel formed by iridium prisms and indium atoms of the honeycomb lattice.

  14. (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.

  15. 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.

  16. Synthesis, crystal structure investigation and magnetism of the complex metal-rich boride series Cr{sub x}(Rh{sub 1-y}Ru{sub y}){sub 7-x}B{sub 3} (x=0.88-1; y=0-1) with Th{sub 7}Fe{sub 3}-type structure

    SciTech Connect

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

    2012-08-15

    Powder samples and single crystals of the new complex boride series Cr{sub x}(Rh{sub 1-y}Ru{sub y}){sub 7-x}B{sub 3} (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 Th{sub 7}Fe{sub 3} structure type (space group P6{sub 3}mc, 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. - Graphical abstract: The new complex boride series Cr{sub x}(Rh{sub 1-y}Ru{sub y}){sub 7-x}B{sub 3} (x=0.88-1; y=0-1) has been synthesized by arc melting the elements under purified argon atmosphere. Beside the 3d/4d site preference within the whole solid solution, an unexpected Rh/Ru site preference was found in the Ru-rich region only, leading to two different magnetic behaviors: The Rh-rich region shows a temperature-independent (Pauli) paramagnetism whereas an additional temperature-dependent paramagnetic component is found in the Ru-rich region. Highlights: Black-Right-Pointing-Pointer Synthesis of a new boride series fulfilling Vegard Acute-Accent s rule. Black-Right-Pointing-Pointer 3d/4d site preference. Black-Right-Pointing-Pointer Unexpected Ru/Rh site preference. Black-Right-Pointing-Pointer Rh-rich region is Pauli paramagnetic. Black-Right-Pointing-Pointer Ru-rich region is Pauli and temperature-dependent paramagnetic.

  17. The complex metal-rich boride Ti{sub 1+x}Rh{sub 2-x+y}Ir{sub 3-y}B{sub 3} (x=0.68, y=1.06) with a new structure type containing B{sub 4} zigzag fragments: Synthesis, crystal chemistry and theoretical calculations

    SciTech Connect

    Goerens, Christian; Fokwa, Boniface P.T.

    2012-08-15

    Polycrystalline samples and single crystals of the new complex boride Ti{sub 1+x}Rh{sub 2-x+y}Ir{sub 3-y}B{sub 3} (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 B{sub 4} fragments as well as isolated boron atoms crystallizes in the orthorhombic space group Pbam (Nr. 55) with the lattice parameters a=8.620(1) A, b=14.995(2) A and c=3.234(1) A. 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 B{sub 4} 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. - graphical abstract: The structure of Ti{sub 1.68(2)}Rh{sub 2.38(6)}Ir{sub 1.94(4)} B{sub 3}, a new structure type containing planar trans zigzag B{sub 4} units, is another example which illustrates the tendency of metal-rich borides to form B-B bonds with increasing boron content. Beside the B{sub 4} fragment it exhibits one-dimensional chains of titanium atoms and hold one-dimensional strings of face-sharing empty tetrahedral and square pyramidal clusters (see figure). Highlights

  18. 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.

  19. 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.

  20. Computer Modeling of Ceramic Boride Composites

    DTIC Science & Technology

    2014-11-01

    Distribution A: Approved for public release; distribution is unlimited. The above simulations reproduce the process of the formation of the spatial ... seeding is made. Such a revision repeats 2 2f − times. In the course of revision, an attempt for Distribution A: Approved for public release...in total, 2an seeding attempts are made. • f — size of the full-grown fiber. • g — dead zone width: Distribution A: Approved for public

  1. Thermal analysis, phase equilibria, and superconducting properties in magnesium boride and carbon doped magnesium boride

    NASA Astrophysics Data System (ADS)

    Bohnenstiehl, Scot David

    In this work, the low temperature synthesis of MgB2 from Mg/B and MgH2/B powder mixtures was studied using Differential Scanning Calorimetry (DSC). For the Mg/B powder mixture, two exothermic reaction events were observed and the first reaction event was initiated by the decomposition of Mg(OH)2 on the surface of the magnesium powder. For the MgH 2/B powder mixture, there was an endothermic event at ˜375 °C (the decomposition of MgH2 into H2 and Mg) and an exothermic event ˜600 °C (the reaction of Mg and B). The Kissinger analysis method was used to estimate the apparent activation energy of the Mg and B reaction using DSC data with different furnace ramp rates. The limitations of MgB2 low temperature synthesis led to the development of a high pressure induction furnace that was constructed using a pressure vessel and an induction heating power supply. The purpose was to not only synthesize more homogeneous MgB2 samples, but also to determine whether MgB2 melts congruently or incongruently. A custom implementation of the Smith Thermal Analysis method was developed and tested on aluminum and AlB2, the closest analogue to MgB2. Measurements on MgB2 powder and a high purity Mg/B elemental mixture confirmed that MgB2 melts incongruently and decomposes into a liquid and MgB4 at ˜1445 °C at 10 MPa via peritectic decomposition. Another measurement using a Mg/B elemental mixture with impure boron suggested that ˜0.7 wt% carbon impurity in the boron raised the incongruent melting temperature to ˜1490-1500 °C. Lastly, the solubility limit for carbon in MgB2 was studied by making samples from B4C and Mg at 1530 °C, 1600 °C and 1700 °C in the high pressure furnace. All three samples had three phases: Mg, MgB2C2, and carbon doped MgB2. The MgB 2C2 and carbon doped MgB2 grain size increased with temperature and the 1700 °C sample had needle-like grains for both phases. The presence of the ternary phase, MgB2C2, suggested that the maximum doping limit for carbon in MgB2 had been reached. The 1530 °C sample was characterized by Electron Probe Microanalysis at the University of Oregon and the average carbon concentration was estimated to be ˜5.9 at%. Further investigation using TEM found MgO inclusions in the 1530 °C sample which were not detected with X-ray diffraction.

  2. Improving hardness and toughness of boride composites based on aluminum magnesium boride

    NASA Astrophysics Data System (ADS)

    Peters, Justin Steven

    The search for new super-hard materials has usually focused on strongly bonded, highly symmetric crystal structures similar to diamond. The two hardest single-phase materials, diamond and cubic boron nitride (cBN), are metastable, and both must be produced at high temperatures and pressures, which makes their production costly. In 2000, a superhard composite based on a low-symmetry, boron-rich compound was reported. Since then, many advances have been made in the study of this AlMgB14--TiB2 composite. The composite has been shown to exhibit hardness greater than either of its constituent phases, relying on its sub-micron microstructure to provide hardening and strengthening mechanisms. With possible hardness around 40 GPa, an AlMgB 14--60 vol% TiB2 approaches the hardness of cBN, yet is amenable to processing under ambient pressure conditions. There are interesting aspects of both the AlMgB14 and TiB 2 phases. AlMgB14 is comprised of a framework of boron, mostly in icosahedral arrangements. It is part of a family of 12 known compounds with the same boron lattice, with the metal atoms replaced by Li, Na, Y or a number of Lanthanides. Another peculiar trait of this family of compounds is that every one contains a certain amount of intrinsic vacancies on one or both of the metal sites. These vacancies are significant, ranging from 3 to 43% of sites depending on the composition. TiB2 is a popular specialty ceramic material due to its high hardness, moderate toughness, good corrosion resistance, and high thermal and electrical conductivity. The major drawback is the difficulty of densification of pure TiB2 ceramics. A combination of sintering aids, pressure, and temperatures of 1800°C are often required to achieve near full density articles. The AlMgB14--TiB2 composites can achieve 99% density from hotpressing at 1400°C. This is mostly due to the preparation of powders by a high-energy milling technique known as mechanical alloying. The resulting fine powders have high activity, and Fe from wear debris acts as a sintering aid. Mechanical alloying improves the sinterability of the composite material, it has the same effect on pure TiB2. TiB 2 processed by high-energy milling has been found to achieve 99% theoretical density at 1400°C with the addition of ˜1 wt% Fe. Both the AlMgB14--TiB2 composites and pure TiB2 produced from these methods have enhanced mechanical properties due to their fine microstructures. These materials show exceptional promise in the field of wear resistance. This includes cutting tools, erosion resistant coatings, and low-friction sliding contacts to name a few. Under certain wear conditions, the composite material can show performance on par with that of current high-end cBN and WC materials tailored for wear resistance. The composite material also exhibits low reactivity with Ti alloys, a pre-requisite for effective machining of these alloys, a trait that few hard materials possess.

  3. Scaffolds of magnetically active 3d metals in the valence electron controlled borides Ti{sub 9−x}M{sub 2+x}Ru{sub 18}B{sub 8} (M=Cr–Ni; x=0.5–1): Structutral, electronic and magnetic properties

    SciTech Connect

    Goerens, Christian; Brgoch, Jakoah; Miller, Gordon J.; Fokwa, Boniface P.T.

    2013-08-15

    Polycrystalline samples of the boride series Ti{sub 9−x}M{sub 2+x}Ru{sub 18}B{sub 8} (M=Cr, Co, Mn, Ni) including single crystals of Ti{sub 8}Co{sub 3}Ru{sub 18}B{sub 8} have been prepared by arc-melting the elements. The phases were characterized by powder X-ray diffraction (Rietveld refinement), single-crystal X-ray diffraction (for M=Co), and energy-dispersive X-ray (EDX) analysis. They are substitutional variants of the Zn{sub 11}Rh{sub 18}B{sub 8} structure type, space group P4/mbm (No. 127) and contain a “scaffold” structural unit (M-ladders interacting with M/Ti-chains) as well as isolated M/Ti-chains. According to DFT calculations, the Ru–X (X=B, Ti, Ti/M) bonding interactions are nearly constant throughout the series and responsible for the structural stability of these phases, whereas the M–M and Ru–M interactions vary significantly with varying valence electron count. Furthermore, density of states (DOS) analyses predict the phases with M=Mn and Ni to develop a total magnetic moment but not the M=Co phase. Susceptibility measurements confirm the Co phase to be paramagnetic and the Mn Phase orders ferrimagnetically below 120 K and thus develops a magnetic moment, as predicted. - Graphical abstract: The crystal structures of the new phases (M=Cr, Mn, Co, Ni) are confirmed by Rietveld refinement of powder diffraction data and single crystal X-ray diffraction (for M=Co) to contain beside the M-ladder also M/Ti-chains. Similar to the series Ti{sub 9}M{sub 2}Ru{sub 18}B{sub 8}, the crystal structure of the new phases are mainly stabilized by the heteroatomic Ru–B and Ru–Ti bonds that remain nearly constant throughout the series, whereas the M-containing bonds vary significantly with varying valence electron count. An experimental finding confirmed and even extended by COHP bonding analyses. In addition, the DOS analyses of the M-elements reveal the development of magnetic moments for the M=Mn, Ni cases but not for M=Co. Indeed, Ti{sub 8}Co

  4. (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

    SciTech Connect

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

    2015-09-15

    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{sub 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

  5. New members of ternary rare-earth metal boride carbides containing finite boron-carbon chains: RE{sub 25}B{sub 14}C{sub 26} (RE=Pr, Nd) and Nd{sub 25}B{sub 12}C{sub 28}

    SciTech Connect

    Babizhetskyy, Volodymyr; Mattausch, Hansjuergen; Simon, Arndt; Gautier, Regis; Halet, Jean-Francois

    2011-07-15

    New ternary rare-earth metal boride carbides RE{sub 25}B{sub 14}C{sub 26} (RE=Pr, Nd) and Nd{sub 25}B{sub 12}C{sub 28} were synthesized by co-melting the elements. Nd{sub 25}B{sub 12}C{sub 28} is stable up to 1440 K. RE{sub 25}B{sub 14}C{sub 26} (RE=Pr, Nd) exist above 1270 K. The crystal structures were investigated by means of single-crystal X-ray diffraction. Nd{sub 25}B{sub 12}C{sub 28}: space group P1-bar, a=8.3209(7) A, b=8.3231(6) A, c=29.888(2) A, {alpha}=83.730(9){sup o}, {beta}=83.294(9){sup o}, {gamma}=89.764(9){sup o}. Pr{sub 25}B{sub 14}C{sub 26}: space group P2{sub 1}/c, a=8.4243(5) A, b=8.4095(6) A, c=30.828(1) A, {beta}=105.879(4){sup o}, V=2100.6(2) A{sup 3}, (R1=0.048 (wR2=0.088) from 2961 reflections with I{sub o}>2{sigma}(I{sub o})); for Nd{sub 25}B{sub 14}C{sub 26} space group P2{sub 1}/c, Z=2, a=8.3404(6) A, b=8.3096(6) A, c=30.599(2) A, {beta}=106.065(1){sup o}. Their structures consist 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 cumulene-like molecules [B{sub 2}C{sub 4}]{sup 6-} and [B{sub 3}C{sub 3}]{sup 7-}, nearly linear [BC{sub 2}]{sup 5-} and bent [BC{sub 2}]{sup 7-} units and isolated carbon atoms. Structural and theoretical analysis suggests the ionic formulation for RE{sub 25}B{sub 14}C{sub 26}: (RE{sup 3+}){sub 25}[B{sub 2}C{sub 4}]{sup 6-}([B{sub 3}C{sub 3}]{sup 7-}){sub 2}([BC{sub 2}]{sup 5-}){sub 4}([BC{sub 2}]{sup 7-}){sub 2}(C{sup 4-}){sub 4}.5e{sup -} and for Nd{sub 25}B{sub 12}C{sub 28}: (Nd{sup 3+}){sub 25}([B{sub 2}C{sub 4}]{sup 6-}){sub 3}([BC{sub 2}]{sup 5-}){sub 4}([BC{sub 2}]{sup 7-}){sub 2}(C{sup 4-}){sub 4}.7e{sup -}. Accordingly, extended Hueckel tight-binding calculations indicate that the compounds are metallic in character. - Graphical Abstract: New ternary rare-earth metal boride carbides RE{sub 25}B{sub 14}C{sub 26} (RE=Pr, Nd) and Nd{sub 25}B{sub 12}C{sub 28} were synthesized by co

  6. Lutetium-177 Labeled Peptides: The European Institute of Oncology Experience.

    PubMed

    Carollo, Angela; Papi, Stefano; Chinol, Marco

    2016-01-01

    Peptide receptor radionuclide therapy (PRRT) using radiolabeled somatostatin analogues has shown encouraging results in various somatostatin receptor positive tumors. Partial remission rates up to 30% have been documented as well as significant improvements in quality of life and survival. This treatment takes advantage of the high specific binding of the radiolabeled peptide to somatostatin receptors overexpressed by the tumors thus being more effective on the tumor cells with less systemic side-effects. The development of macrocyclic chelators conjugated to peptides made possible the stable binding with various radionuclides. In particular 177Lu features favourable physical characteristics with a half-life of 6.7 days, emission of β- with energy of 0.5 MeV for treatment and γ-emissions suitable for imaging. The present contribution describes the learning process achieved at the European Institute of Oncology (IEO) since the first application of 90Y labeled peptides to the therapy of neuroendocrine tumors back in 1997. Continuous improvements led to the preparation of a safe 177Lu labeled peptide for human use. Our learning curve began with the identification of the optimal characteristics of the isotope paying attention to its chemical purity and specific activity along with the optimization of the parameters involved in the radiolabeling procedure. Also the radiation protection issues have been improved along the years and recently more and more attention has been devoted to the pharmaceutical aspects involved in the preparation. The overall issue of the quality has now been completed by drafting an extensive documentation with the goal to deliver a safe and reliable product to our patients.

  7. Electrochromic lutetium phthalocyanine films for in situ detection of NADH

    NASA Astrophysics Data System (ADS)

    Basova, Tamara; Gürek, Ayşe Gül; Ahsen, Vefa; Ray, Asim

    2013-01-01

    A simple and sensitive method for the detection of NADH on a glass substrate modified with spin coated electrochromic [(C6H13S)8Pc]2Lu is presented. The modification of a [(C6H13S)8Pc]2Lu sensing layer was achieved chemically. The functionalized layer shows an efficient activity towards the NADH at conc. as low as 1 × 10-5 M. The in situ UV-Vis and Raman measurements were carried out to study the interaction of oxidized films with NADH. The electrochromic behaviour of [(C6H13S)8Pc]2Lu thin films was examined in detail under various conditions. The spin coated films deposited on glass substrate were chemically oxidized and were found to change the colour. The oxidized films were believed to be reduced to its natural form on interaction with NADH. The colour of the film changed from green to brownish-purple after interaction with NADH. Reversible electrochromism was observed, leading reusable sensor film. The transformation of the oxidised phthalocyanine films into neutral form was monitored by both in situ UV-Vis and Raman techniques.

  8. Phonon spectra of terbium-doped lutetium orthophosphates

    NASA Astrophysics Data System (ADS)

    Moura, M. R.; Ayala, A. P.; Guedes, I.; Loong, C.-K.; Boatner, L. A.

    2004-12-01

    Raman spectroscopy has been applied to investigations of the effects of substitutionally replacing Lu by Tb in single crystals of the tetragonal, zircon structure host LuPO4. Room-temperature, polarized Raman spectra of Lu1-xTbxPO4 (x =0, 0.01, 0.1, and 0.12) have been studied. No appreciable changes in the frequencies of the phonons were observed, indicating that the force fields in the LuPO4 lattice are not strongly altered by Tb doping on the Lu site. A discussion of the fluorescence bands and a revised assignment of the LuPO4 vibrations are presented.

  9. Resonance transition energies and oscillator strengths in lutetium and lawrencium.

    PubMed

    Zou, Yu; Fischer, C Froese

    2002-05-06

    The transition energies and oscillator strengths for nd (2)D(3/2)-(n+1)p (2)P(o)(1/2,3/2) transitions in Lu ( n = 5, Z = 71) and Lr ( n = 6, Z = 103) were calculated with the multiconfiguration Dirac-Hartree-Fock method. The present study confirmed that the ground state of atomic Lr is [Rn]5f(14)7s(2)7p (2)P(o)(1/2). The calculation for Lr required wave function expansions of more than 330 000 configuration states. In Lu, the transition energies, with Breit and QED corrections included, agree with experiment to within 126 cm(-1). In lighter elements, core correlation is usually neglected but was found to be of extreme importance for these heavy elements, affecting the oscillator strengths by a factor of 3 and 2 in Lu and Lr, respectively.

  10. Lutetium-labelled peptides for therapy of neuroendocrine tumours.

    PubMed

    Kam, B L R; Teunissen, J J M; Krenning, E P; de Herder, W W; Khan, S; van Vliet, E I; Kwekkeboom, D J

    2012-02-01

    Treatment with radiolabelled somatostatin analogues is a promising new tool in the management of patients with inoperable or metastasized neuroendocrine tumours. Symptomatic improvement may occur with (177)Lu-labelled somatostatin analogues that have been used for peptide receptor radionuclide therapy (PRRT). The results obtained with (177)Lu-[DOTA(0),Tyr(3)]octreotate (DOTATATE) are very encouraging in terms of tumour regression. Dosimetry studies with (177)Lu-DOTATATE as well as the limited side effects with additional cycles of (177)Lu-DOTATATE suggest that more cycles of (177)Lu-DOTATATE can be safely given. Also, if kidney-protective agents are used, the side effects of this therapy are few and mild and less than those from the use of (90)Y-[DOTA(0),Tyr(3)]octreotide (DOTATOC). Besides objective tumour responses, the median progression-free survival is more than 40 months. The patients' self-assessed quality of life increases significantly after treatment with (177)Lu-DOTATATE. Lastly, compared to historical controls, there is a benefit in overall survival of several years from the time of diagnosis in patients treated with (177)Lu-DOTATATE. These findings compare favourably with the limited number of alternative therapeutic approaches. If more widespread use of PRRT can be guaranteed, such therapy may well become the therapy of first choice in patients with metastasized or inoperable neuroendocrine tumours.

  11. Lutetium-177 Labeled Bombesin Peptides for Radionuclide Therapy.

    PubMed

    Reynolds, Tamila Stott; Bandari, Rajendra P; Jiang, Zongrun; Smith, Charles J

    2016-01-01

    The rare-earth radionuclides that decay by beta particle (β-) emission are considered to be ideal in the context of targeted radiotherapy. The rare-earth isotopes exist primarily in the 3+ oxidation state and are considered to be hard metal centers, requiring multidentate, hard donor ligands such as the poly(aminocarboxylates) for in vivo kinetic inertness. 177Lu is a rare-earth radionuclide that is produced in moderate specific activity (740 GBq/mg) by direct neutron capture of enriched 176Lu via the 176Lu(n,γ)177Lu nuclear reaction. 177Lu has a half-life of 6.71 d, decays by beta emission (Ebmax = 0.497 MeV), and emits two imagable photons (113keV, 3% and 208kev, 11%). High specific activity, no-carrier-added 177Lu can also be prepared by an indirect neutron capture nuclear reaction on a 176Yb target. Herein, we report upon bombesin (BBN) peptides radiolabeled with 177Lu. The impetus driving many of the research studies that we have described in this review is that the high-affinity gastrin releasing peptide receptor (GRPR, BBN receptor subtype 2, BB2) has been identified in tissue biopsy samples and immortalized cell lines of many human cancers and is an ideal biomarker for targeting early-stage disease. Early on, the ability of GRPR agonists to be rapidly internalized coupled with a high incidence of GRPR expression on various neoplasias was a driving force for the design and development of new diagnostic and therapeutic agents targeting GRP receptor-positive tumors. Recent reports, however, show compelling evidence that radiopharmaceutical design and development based upon antagonist-type ligand frameworks clearly bears reexamination. Last of all, the ability to target multiple biomarkers simultaneously via a heterodimeric targeting ligand has also provided a new avenue to investigate the dual targeting capacity of bivalent radioligands for improved in vivo molecular imaging and treatment of specific human cancers. In this report, we describe recent advances in 177Lu-labeled bombesin peptides for targeted radiotherapy that includes agonist, antagonist, and multivalent cell-targeting agents. In vitro, in vivo translational, and in vivo human clinical investigations are described.

  12. Turn-on fluorescent chemosensor for determination of lutetium ion.

    PubMed

    Faridbod, F; Sedaghat, M; Hosseini, M; Ganjali, M R; Khoobi, M; Shafiee, A; Norouzi, P

    2015-02-25

    A turn-on fluorescent chemosensor is introduced for the detection of Lu(3+) ion using N-[3-methyl]-2-[pyridine-2-amido] phenyl] pyridine-2-carboxamide (L) molecule. Fluorescent emission intensity of L enhances after binding to Lu(3+) ions in ethanol-water solution (1:9, v/v). The observed enhancement is the result of a strong covalent binding between Lu(3+) ion and L (the binding constant value is 2.0×10(6) mol(-1) L). The proposed optical chemosensor can be applied for the analysis of Lu(3+) ion in a linear range of 3.3×10(-7) to 1.0×10(-5) mol L(-1). The limit of detection was obtained 8.6×10(-7) mol L(-1). The probe exhibits high selectivity toward Lu(3+) ion in comparison with common metal ions. The proposed fluorescent chemosensor was successfully used in the determination of Lu(3+) ion in some water samples. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Investigation of magnetic properties and electronic structure of layered-structure borides AlT{sub 2}B{sub 2} (T=Fe, Mn, Cr) and AlFe{sub 2–x}Mn{sub x}B{sub 2}

    SciTech Connect

    Chai, Ping; Stoian, Sebastian A.; Tan, Xiaoyan; Dube, Paul A.; Shatruk, Michael

    2015-04-15

    magnetic properties of these materials. - Graphical abstract: We follow a gradual evolution of magnetic properties in a series of ternary borides AlT{sub 2}B{sub 2}, from non-magnetic AlCr{sub 2}B{sub 2} and AlMn{sub 2}B{sub 2} to ferromagnetic AlFe{sub 2}B{sub 2}. - Highlights: • AlT{sub 2}B{sub 2} (T=Fe, Mn, Cr) and AlFe{sub 2−x}Mn{sub x}B{sub 2} were prepared by arc‐melting. • Bulk ferromagnetism of AlFe{sub 2}B{sub 2} is gradually suppressed by the introduction of Mn. • AlMn{sub 2}B{sub 2} and AlCr{sub 2}B{sub 2} do not exhibit magnetic ordering. • Nonmagnetic (Mn‐rich) and ferromagnetic (Fe‐rich) clustering in AlFe{sub 2–x}Mn{sub x}B{sub 2}. • Ferromagnetism is suppressed due to weakening of antibonding T–T interactions.

  14. Fundamental Thermal and Mechanical Properties of Boride Ceramics

    DTIC Science & Technology

    2014-02-28

    approved for public release. 6 Figure 1. Neutron diffraction intensity as a function of temperature for representative Zr11B2 and SiC planes...of structure-property relationships began by measuring the magnitude of thermal residual stresses in ZrB2-SiC ceramics. Neutron diffraction and...the isotopes of boron, 10B, is a strong neutron absorber and its content was minimized in the ceramics for this study. Ceramics were prepared from

  15. Rare Earth Boride Electron Emitter Materials Fabrication and Evaluation.

    DTIC Science & Technology

    1982-03-01

    Schmid and D. W. Lamson, Anal. Chem. 30 (1958) 953. 10. Complexometric Titrations , G. Schwarzenbach and H. Flashka, translated by HN !Nf Irving, p. 194...melted float zone method is preferable. The only advantage of the much more costly laser and RF melt methods is the possibility of fabricating larger... titration procedure in which excess acid used for disso- lution of RB, is neutralized to pH 7, followed by addition of manitol. This converts HI BO to a

  16. Lithium boride sheet and nanotubes: structure and hydrogen storage.

    PubMed

    Zhang, Hong; Wang, Jing; Tian, Zhi-Xue; Liu, Ying

    2015-06-07

    A new class of Li-B sheets, along with the related nanotubes, with a Li2B5 primitive cell has been designed using first-principles density functional theory. The dynamical stability of the proposed structures was confirmed by calculation of the soft phonon modes, and the calculated electronic structures show that all are metallic. The application of both the sheets and nanotubes for hydrogen storage has been investigated and it has been found that both of them can adsorb two H2 molecules around each Li atom, with an average binding energy of 0.152-0.194 eV per H2, leading to a gravimetric density of 10.6 wt%.

  17. Designing thin film materials — Ternary borides from first principles

    PubMed Central

    Euchner, H.; Mayrhofer, P.H.

    2015-01-01

    Exploiting the mechanisms responsible for the exceptional properties of aluminum based nitride coatings, we apply ab initio calculations to develop a recipe for designing functional thin film materials based on ternary diborides. The combination of binary diborides, preferring different structure types, results in supersaturated metastable ternary systems with potential for phase transformation induced effects. For the exemplary cases of MxW1 − xB2 (with M = Al, Ti, V) we show by detailed ab initio calculations that the respective ternary solid solutions are likely to be experimentally accessible by modern depositions techniques. PMID:26082562

  18. Development of Boride Composite Materials for Cold Cathode Devices

    DTIC Science & Technology

    1981-05-01

    22 7. Diagram of the Induction Heating Facilities .. .. .....24 8. Typical Pellet After RF Heating...technique in an RF induction furnace. Pellets of the eu- tectic composition available from the literature were melted as well as pellets of a composition...com- pounds with the metals and metal oxides . Pure boron is silvery gray in color. In order to avoid reactions with Other materials at high tempera

  19. Investigation of the fracture mechanics of boride composites

    NASA Technical Reports Server (NTRS)

    Clougherty, E. V.; Pober, R. L.; Kaufman, L.

    1972-01-01

    Significant results were obtained in fabrication studies of the role of metallic additives of Zr, Ti, Ni, Fe and Cr on the densification of ZrB2. All elemental additions lower the processing temperatures required to effect full densification of ZrB2. Each addition effects enhanced densification by a clearly distinguishable and different mechanism and the resulting fabricated materials are different. A significant improvement in strength and fracture toughness was obtained for the ZrB2/Ti composition. Mechanical characterization studies for the ZrB2/SiC/C composites and the new ZrB2/Metal materials produced data relevant to the effect of impacting load on measured impact energies, a specimen configuration for which controlled fracture could occur in a suitably hard testing apparatus, and fracture strength data. Controlled fracture--indicative of measurable fracture toughness--was obtained for the ZrB2-SiC-C composite, and a ZrB2/Ti composite fabricated from ZrB2 with an addition of 30 weight per cent Ti. The increased strength and toughness of the ZrB2/Ti composite is consistent with the presence of a significantly large amount of a fine grained acicular phase formed by reaction of Ti with ZrB2 during processing.

  20. PREFACE: Anisotropic and multiband pairing: from borides to multicomponent superconductivity Anisotropic and multiband pairing: from borides to multicomponent superconductivity

    NASA Astrophysics Data System (ADS)

    Annett, James; Kusmartsev, Feodor; Bianconi, Antonio

    2009-01-01

    In 2001, the discovery of superconductivity in MgB2 rapidly led to the understanding that its complex multi-sheeted Fermi surface had two distinct values of the gap parameter Δ, each with its own characteristic temperature dependence. While the theory of multigap superconductivity had been developed long ago, this was the first well studied example where multigap behaviour was observed clearly, and indeed is essential to understand the full superconducting properties of the material. Following this discovery, evidence for multigap behaviour has appeared in a number of materials, including cuprates, ruthenates, and most recently the iron pnictides. As well as multigap pairing on different Fermi-surface sheets, strong gap anisotropy in k-space and strong modulations of the gap in real space (e.g. stripes and phase separation models) are also important in cuprates. The aim of this special section is to present a selection of high-quality papers from experts in these diverse systems, showing the links and common physical issues arising from the existence of multi-component Cooper pairing. The papers collected together for the special section provide a snapshot of the current state of the understanding of multi-component superconductivity in a wide range of materials. In a model motivated by MgB2, Tanaka and Eschrig describe Abrikosov vortex lattice in a two-gap superconductor, examining how the vortex structure is modified by three-dimensionality or quasi two-dimensionality of the Fermi surface. The multi-sheeted Fermi surfaces of the nickel borocarbides are probed using angle-resolved positron annihilation spectroscopy, described by Dugdale et al, leading to a full three-dimensional picture of the complex Fermi surface in this superconducting material. Possible evidence for multigap superconductivity in the iron pnictides, obtained using Andreev point contact spectroscopy, is described by Samuely et al. The iron pnictides are also the subject of the article by Caivano et al, in which it is proposed that the Feschbach resonance mechanism operating near to a quantum critical point may lead to stripe-like fluctuations in these materials. A number of papers describe multigap-related effects in high-Tc superconductors. In particular, Atkinson shows how the existence of CuO chain states at the Fermi surface leads to a set of resonances in the induced gap in the chain layer, which have a pronounced effect on the vortex core shape. Kristoffel et al discuss the existence of the two coherence lengths in two-gap superconductors, and describe how this leads to spatially periodic fluctuations, with possible application to high-temperature superconductivity. Kugel et al describe a scenario for phase separation due to long-range Coulomb forces leading to microstrain and nanoscale inhomogeneities in high-Tc cuprates. Kusmartsev and Saarela also argue that charge over-screening may lead to 'Coulomb bubbles' in high-Tc superconductors. Finally, Wysokiński et al describe multigap effects in strontium ruthenate, in particular the effects on the NMR relaxation rate spectra, which are obtained for NMR on different nuclear species.

  1. Co-precipitation synthesis of lutetium aluminum garnet (LuAG) powders: The influence of ethanol

    NASA Astrophysics Data System (ADS)

    Pan, Liangjie; Jiang, Benxue; Fan, Jintai; Zhang, Pande; Mao, Xiaojian; Zhang, Long

    2017-09-01

    Aluminum Garnet (LuAG) precursors were co-precipitated by using ethanol-water as the precipitant solvent. The effect of different volume ratios of ethanol to water (R) on the preparation of pure-phase LuAG powders has been mainly studied. The evolution of phase, composition and micro-structure of the as-synthesized LuAG powders were characterized by TG/DTA, FTIR, XRD, BET, and SEM. The BET-equivalent diameter of LuAG nano particles increased with R. The ethanol-water solvent does not change the main composition of the LuAG precursors, but has great influence on the morphology of the final LuAG nano particles. Uniformly dispersed LuAG powders calcined at 1200 °C for 3 h with a particle size of approximately 120 nm were obtained by using ethanol-water solvent with proper R = 1. The mechanism of ethanol in the preparation process was discussed.

  2. Syntheses, Structure, Magnetism, and Optical Properties of Lutetium-based Interlanthanide Selenides

    SciTech Connect

    Booth, Corwin H; Jin, Geng Bang; Choi, Eun Sang; Guertin, Robert P.; Brooks, James S.; Booth, Corwin H.; Albrecht-Schmitt, Thomas E.

    2007-10-01

    Ln{sub 3}LuSe{sub 6} (Ln = La, Ce), {beta}-LnLuSe{sub 3} (Ln = Pr, Nd), and Ln{sub x}Lu{sub 4-x}Se{sub 6} (Ln = Sm, Gd; x = 1.82, 1.87) have been synthesized using a Sb{sub 2}Se{sub 3} flux at 1000 C. Ln{sub 3}LuSe{sub 6} (Ln = La, Ce) adopt the U{sub 3}ScS{sub 6}-type three-dimensional structure, which is constructed from two-dimensional {infinity}{sup 2} [Ln{sub 3}Se{sub 6}]{sup 3-} slabs with the gaps between these slabs filled by octahedrally coordinated Lu{sup 3+} ions. The series of {beta}-LnLuSe{sub 3} (Ln = Pr, Nd) are isotypic with UFeS{sub 3}. Their structures include layers formed from LuSe6 octahedra that are separated by eight-coordinate larger Ln{sup 3+} ions in bicapped trigonal prismatic environments. Sm{sub 1.82}Lu{sub 2.18}Se{sub 6} and Gd{sub 1.87}Lu{sub 2.13}Se{sub 6} crystallize in the disordered F-Ln{sub 2}S{sub 3} type structure with the eight-coordinate bicapped trigonal prismatic Ln(1) ions residing in the one-dimensional channels formed by three different double chains via edge and corner sharing. These double chains are constructed from Ln(2)Se{sub 7} monocapped trigonal prisms, Ln(3)Se{sub 6} octahedra, and Ln(4)S{sub 6} octahedra, respectively. The magnetic susceptibilities of {beta}-PrLuSe{sub 3} and {beta}-NdLuSe{sub 3} follow the Curie-Weiss law. Sm{sub 1.82}Lu{sub 2.18}Se{sub 6} shows van Vleck paramagnetism. Magnetic measurements show that Gd{sub 1.87}Lu{sub 2.13}Se{sub 6} undergoes an antiferromagnetic transition around 4 K. Ce{sub 3}LuSe{sub 6} exhibits ferromagnetic ordering below 5 K. The optical band gaps for La{sub 3}LuSe{sub 6}, Ce{sub 3}LuSe{sub 6}, {beta}- PrLuSe{sub 3}, {beta}-NdLuSe{sub 3}, Sm{sub 1.82}Lu{sub 2.18}Se{sub 6}, and Gd{sub 1.87}Lu{sub 2.13}Se{sub 6} are 1.26, 1.10, 1.56, 1.61, 1.51, and 1.56 eV, respectively.

  3. Transition energies of ytterbium, lutetium, and lawrencium by the relativistic coupled-cluster method

    SciTech Connect

    Eliav, E.; Kaldor, U.; Ishikawa, Y.

    1995-07-01

    The relativistic Fock-space coupled-cluster method was applied to the Yb, Lu, and Lr atoms, and to several of their ions. A large number of transition energies was calculated for these systems. Starting from an all-electron Dirac-Fock or Dirac-Fock-Breit function, many electrons (30--40) were correlated to account for core-valence polarization. High-{ital l} virtual orbitals were included (up to {ital l}=5) to describe dynamic correlation. Comparison with experiment (when available) shows agreement within a few hundred wave numbers in most cases. Fine-structure splittings are even more accurate, within 30 cm{sup {minus}1} of experiment. Average errors are at least three times smaller than for previous calculations. Two bound states of Lu{sup {minus}} are predicted, 6{ital p}5{ital d} {sup 1}{ital D}{sub 2} and 6{ital p}{sup 2} {sup 3}{ital P}{sub 0}, with binding energies of about 2100 and 750 cm{sup {minus}1}, respectively. The ground state of lawrencium is {sup 2}{ital P}{sub 1/2}, relativistically stabilized relative to {sup 2}{ital D}{sub 3/2}, the ground state of Lu. Two states of the Lr{sup {minus}} anion are bound, 7{ital p}{sup 2} {sup 3}{ital P}{sub 0} (by 2500 cm{sup {minus}1}) and 7{ital p}6{ital d} {sup 1}{ital D}{sub 2} (by 1300 cm{sup {minus}1}).

  4. The growth of strontium titanate and lutetium ferrite thin films by molecular-beam epitaxy

    NASA Astrophysics Data System (ADS)

    Brooks, Charles M.

    Included in this work is a range of studies on films of homoeptaxial and heteroepitaxial films of SrTiO3 and the first reported phase-pure films of LuFe2O4. We report the structural properties of homoepitaxial (100) SrTiO3 films grown by reactive molecular-beam epitaxy (MBE). The lattice spacing and x-ray diffraction (XRD) rocking curves of stoichiometric MBEgrown SrTiO3 films are indistinguishable from the underlying SrTiO3 substrates. The effect of off-stoichiometry for both strontium-rich and strontium-poor compositions results in lattice expansion with significant changes to the shuttered reflection high-energy electron diffraction oscillations, XRD, film microstructure, and thermal conductivity. Up to an 80% reduction in Sr(1+x)TiO3 film thermal conductivity is measured for x = -0.1 to 0.5. Significant reduction, from 11.5 to ˜2 W˙m-1K-1, occurs through the formation of Ruddlesden-Popper planar faults. The ability to deposit films with a reduction in thermal conductivity is applicable to thermal barrier coatings and thermoelectrics. Scanning transmission electron microscopy is used to examine the formation of Ruddlesden-Popper planar faults in films with strontium excess. We also show that the band gap of SrTiO3 can be altered by >10% (0.3 eV) by using experimentally realizable biaxial strains providing a new means to accomplish band gap engineering of SrTiO3 and related perovskites. Such band gap manipulation is relevant to applications in solar cells water splitting, transparent conducting oxides, superconductivity, two-dimensional electron liquids, and other emerging oxide electronics. This work also presents the adsorption-controlled growth of single-phase (0001)-oriented epitaxial films of charge ordered multiferroic, LuFe2O4, on (111) MgAl2O4, (111) MgO, and (0001) 6H-SiC substrates in an iron-rich environment at pressures and temperatures where excess iron desorbs from the film surface during growth. Scanning transmission electron microscopy reveals reaction-free film-substrate interfaces. The magnetization increases rapidly below 240 K, consistent with the paramagnetic-to-ferrimagnetic phase transition of bulk LuFe2O4.

  5. Low temperature XAFS investigation on the lutetium binding changes during the 2-line ferrihydrite alteration process.

    PubMed

    Dardenne, K; Schäfer, T; Lindqvist-Reis, P; Denecke, M A; Plaschke, M; Rothe, J; Kim, J I

    2002-12-01

    The time dependent changes of Lu speciation (used as Am(III) homologue), initially sorbed onto 2-line ferrihydrite at pH 5.9, during tempering (70 degrees C) to stable crystalline transformation products, goethite and hematite, is studied. Microscopies (AFM, SEM), XRD and FTIR spectroscopy confirm transformation to both goethite and hematite, with a predominance of hematite. XRD investigation of another transformation series at pH 8.0 (75 degrees C, [Lu(III)initial] 7 times higher) shows that the cell volume of hematite increases, suggesting the incorporation of Lu in the crystal structure. Extended X-ray absorption fine structure (EXAFS) (pH 5.9 series, 70 degrees C) reveals a shortening of the Lu-O bond distance and an increase in asymmetry of the first shell with increasing tempering time in the intermediate temper time samples. The intensity of the second peak in the Fourier transform (FT) of the EXAFS increases and splits into two components. The EXAFS data of the end product can be modeled well using a hematite-like cluster, with an isotropic expansion of distances to account for incorporation of Lu into the hematite structure. These results demonstrate that the Lu is incorporated in the crystal lattice of the transformation product, as opposed to being occluded or remaining a sorbed species on the surface.

  6. Structural and dielectric properties of the lutetium (Lu) and yttrium (Y) doped nickel ferrite

    SciTech Connect

    Ugendar, Kodam Markandeyulu, G.

    2014-04-24

    The structural and dielectric characteristics of NiFe{sub 1.925}R{sub 0.075}O{sub 4} (R=Lu,Y) were investigated. The material crystallize in the cubic inverse spinel phase with a very small amount of RFeO{sub 3} (R=Lu,Y) as the additional phase. Frequency variation of the dielectric constant shows the dispersion that can be modeled with a modified Debye's function, which considers the possibility of more than one ion, contributing to the relaxation. Impedance spectroscopic analysis indicates the different relaxation mechanisms, bulk grain and grain-boundary contributions to the electrical conductivity and capacitance of these materials.

  7. NeuroEndocrine Tumor Therapy with Lutetium-177-octreotate and Everolimus (NETTLE): A Phase I Study.

    PubMed

    Claringbold, Phillip G; Turner, J Harvey

    2015-08-01

    To establish the optimal safe dose of everolimus in combination with (177)Lu-octreotate peptide receptor radionuclide therapy (PRRT) of advanced progressive gastro-entero pancreatic neuroendocrine tumors (GEP-NETs) and to define dose-limiting toxicity. Patients with advanced unresectable progressive well-differentiated GEP-NETS avid for (68)Ga-octreotate on positron emission tomography-computed tomography imaging underwent PRRT with four cycles of 7.8 GBq (177)Lu-octreotate at 8 week intervals. Successive cohorts of 3 patients received escalating doses of everolimus comprising 5, 7.5, and 10 mg daily for 24 weeks. Sixteen patients comprised 4 at 5 mg, 9 at 7.5 mg, and 3 at 10 mg everolimus. Patient cohorts at 5 and 7.5 mg received 83% and 80% of the total planned dose of everolimus over 24 weeks. All patients required dose reduction or complete cessation of everolimus at the 10 mg level, which induced neutropenia and thrombocytopenia, and reduced creatinine clearance. The overall response rate was 44% (7 of 16 patients), and no patient progressed over the 6 month period of treatment. Four of 5 pancreatic NET patients achieved PR 80%. No patient progressed on study. In combination, PRRT with (177)Lu-octreotate, the maximum tolerated dose of everolimus is 7.5 mg daily.

  8. Automated module radiolabeling of peptides and antibodies with gallium-68, lutetium-177 and iodine-131.

    PubMed

    De Decker, Mario; Turner, J Harvey

    2012-02-01

    Our objectives were to automate radiolabeling of therapeutic activities for safe, reliable, cost-effective, practical routine preparation of (177)Lu-radiopeptides, (131)I radioimmunotherapeutic agents, and (68)Ga-peptide PET diagnostics and, in particular, minimize radiation exposure to the radiopharmaceutical chemist. Reprogramming and adaptation of a commercially available synthetic module (IBA molecular; Synthera®) allowed high yield, fully automated, in-house radiolabeling of novel therapeutic and diagnostic radiopharmaceuticals under remote shielded sterile conditions. Radiochemical yield and purity was measured by instant thin-layer chromatography and high-performance liquid chromatography. (68)Ga-octreotate and (177)Lu-octreotate were synthesized, resulting in both radiochemical yield and radiochemical purity greater than 99%. Synthesis of (131)I-rituximab resulted in a yield of 60%, with a radiochemical purity greater than 99%. Using 400 MBq (68)GaCl(3) per synthesis, the estimated absorbed body and hand dose for a manual synthesis was 2 and 27 μ Sv, contrasting with automated synthesis exposure of 1.3 and 7.9 μ Sv. Using 8000 MBq (177)LuCl(3) per synthesis, the estimated absorbed body and hand dose for a manual synthesis was 44.7 and 75 μ Sv, contrasting with automated synthesis exposure of 2.5 and 20 μ Sv. Using 6000 MBq (131)I per synthesis, the estimated absorbed body and hand dose for a manual synthesis was 83.7 and 335 μ Sv, contrasting with automated synthesis exposure of 10.9 and 54.7 μ Sv. The reduction in radiation exposure by automated synthesis of radiopharmaceuticals in the Synthera® module was at least five fold. Automated synthesis of therapeutic (177)Lu and (131)I radiopharmaceuticals and (68)Ga PET agents in the shielded sterile Synthera® module is simple, practical, and efficient and virtually eliminates radiation exposure to the radiopharmaceutical chemist.

  9. Lutetium-177-labeled gastrin releasing peptide receptor binding analogs: a novel approach to radionuclide therapy.

    PubMed

    Panigone, S; Nunn, A D

    2006-12-01

    Optimization of therapy for individual patients remains a goal of clinical practice. Radionuclide imaging can identify those patients who may benefit from subsequent targeted therapy by providing regional information on the distribution of the target. An ideal situation may be when the imaging and the therapeutic compounds are the same agent. Two antibodies ([ [90Y]ibritumomab, [131I]tositumomab) are now approved for the systemic radiotherapy of non-Hodgkin's lymphoma. The main hurdle is to deliver higher absorbed doses to the more refractory solid tumors paying particular regard to the bone marrow toxicity. The low dose is thought to be a result of the large size of antibodies slowing delivery to the target. Peptides having high affinity to receptors expressed on cancer cells are a promising alternative. They are usually rapidly excreted from the body through renal and/or hepatobiliary excretion thus creating a prolonged accumulation of the radioactivity in the kidneys, which represents a recognized issue for systemic radiotherapy. The first radiopeptide developed was a somatostatin analogue, which led to a major breakthrough in the field. Beside the kidney issue, somatostatin use remains limited to few cancers that express receptors in sufficiently large quantities, mainly neuroendocrine tumors. The gastrin releasing peptide (GRP) receptor is an attractive target for development of new radiopeptides with diagnostic and therapeutic potential. This is based upon the functional expression of GRP receptors in several of the more prevalent cancers including prostate, breast, and small cell lung cancer. This review covers the efforts currently underway to develop new and clinically promising GRP-receptor specific molecules labeled with imageable and therapeutic radionuclides.

  10. Advantage of lutetium-177 versus radioiodine immunoconjugate in targeted radionuclide therapy of b-cell tumors.

    PubMed

    Repetto-Llamazares, Ada; Abbas, Nasir; Bruland, Øyvind S; Dahle, Jostein; Larsen, Roy H

    2014-07-01

    We herein report a comparison of the radiolabels 177Lu and 125I bound to the monoclonal antibody HH1 that targets the CD37 antigen expressed on non-Hodgkin B-cell lymphomas. Mixtures of 177Lu and 125I-labeled HH1 antibody were co-injected into nude mice carrying Ramos xenografts and the biodistribution using the paired label format allowing tracer comparisons in each individual mouse. Products of the two radionuclides had very similar immunoractivity in vitro but showed different properties in vivo. Both products had relevant stability in blood and most normal tissues in nude mice carrying subcutaneous Ramos xenografts. However, both the tumor uptake and retention were significantly higher for 177Lu vs. 125I labeled HH1. The tumor to normal tissue ratios were several-fold improved for 177Lu compared to radioiodine labeled antibodies. The data presented herein support the evaluation of CD37 as a target for clinical 177Lu-based radioimmunotherapy against b-cell malignancies. Copyright© 2014 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  11. The isolation of lutetium from gadolinium contained in Purex process solutions

    SciTech Connect

    Bostick, D.T.; Vick, D.O.; May, M.P.; Walker, R.L.

    1992-09-01

    A chemical separation procedure has been devised to isolate Lu from Purex dissolver solutions containing the neutron poison, Gd. The isolation procedure involves the removal of U and >Pu from a dissolver solution using tributylphosphate solvent extraction. If required, solvent extraction using di-(2-ethylhexyl) phosphoric acid can be employed to further purify the sample be removing alkali and alkali earth elements. Finally, Lu is chromatographically separated from Gd and rare earth fission products on a Dowex 50W-X8 resin column using an alpha-hydroxyisobutyrate eluant. The success of the chemical separation procedure has been demonstrated in the quantitative recovery of as little as 1.4 ng Lu from solutions containing a 5000-fold excess of Gd. Additionally, Lu has been isolated from synthetic dissolver samples containing U, Ba, Cs, and Gd. Thermal emission MS data indicated that the Lu fraction of the synthetic sample was free of Gd interference.

  12. Production of No-Carrier Added Lutetium-177 by Irradiation of Enriched Ytterbium-176.

    PubMed

    Tarasov, Valery A; Andreev, Oleg I; Romanov, Evgeny G; Kuznetsov, Rostislav A; Kupriyanov, Vladimir V; Tselishchev, Ivan V

    2015-01-01

    Two methods of Lu-177 production are reviewed: irradiation of isotopically enriched Lu- 176 (direct way) and irradiation of ytterbium enriched with Yb-176 (indirect way). Based on neutronphysical calculations Lu-177 yield and specific activity were estimated for both methods. Lu-177 specific activity strongly depends on neutron flux density in the direct way, that is 75,000 Ci/g for 10- days irradiation in a neutron flux of 2.10(15) cm(-2) s(-1), and only 13,000 Ci/g after 30 days irradiation at neutron flux 1.10(14) cm(-2) s(-1). Irradiation of Yb-176 provides Lu-177 specific activity close to theoretical value (110,000 Ci/g). Neutron flux density effect Lu-177 yield, that is 530 Ci/g for 2.1015 cm(-2) s(-1) neutron flux density after 30 days irradiation. A procedure of isolation and purification of Lu-177 from irradiated targets is described based on combination of galvanostatic extraction of ytterbium followed by cation-exchange chromatography from alfa-hydroxyisobutirate solutions on BioRad AG(®)50W-X8 resin.

  13. Fabrication and Characterization of Squeezed Cast Aluminum Matrix Composites Containing Boride Reinforcements

    NASA Astrophysics Data System (ADS)

    Olaya-Luengas, L.; Estremera-Pérez, E.; Muñoz, L.; Suárez, O. M.

    2010-12-01

    Aluminum alloys containing 2 and 4 wt.% copper reinforced with aluminum dodecaborides were successfully fabricated by squeeze casting employing pressures up to 62 MPa. The distribution of reinforcements throughout the composites was quantified, whereas the effect of pressure on the composites density and hardness was determined. In addition, the reinforcement chemical stability was examined using high-temperature x-ray diffraction which permitted to confirm the formation of AlB2 phase a result of AlB12 decomposition. The pressure effect on the squeezed composites was investigated by optical microscopy, Vickers microhardness testing, superficial Rockwell hardness testing, and differential thermal analysis. At the highest applied pressures, the castings density increased when the shrinkage porosity was practically eliminated. The composite superficial hardness improved by increasing the applied squeeze. The indirect squeeze cast technique caused Al2Cu phase segregation to upper regions of the specimens, while conversely, the AlB12 reinforcements segregated preferentially at lower regions of the casting.

  14. 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

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

    DTIC Science & Technology

    2015-02-19

    Scientific Research European Office of Aerospace Research and Development Unit 4515, APO AE 09421-4515 Distribution Statement A: Approved for public...SPONSOR/MONITOR’S REPORT NUMBER(S) AFRL-AFOSR-UK-TR-2015-0021 12. DISTRIBUTION/AVAILABILITY STATEMENT Distribution A: Approved for public release...structure formation of self-reinforced composite materials. For this was supposed to study the eutectic morphology transformation from fiber-like to

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

    DTIC Science & Technology

    2011-05-01

    21 2.1.6. Main mechanical properties of LaB6-(TixZr1-x)B2 composites .............................. 22 2.2. Eutectic composition determination in... properties of alloys in the LaB6-MeB2 system. Table 2. – Lattice parameters of metallic Ti and Zr [14] and of Ti-Zr solid solutions Table 3. – Lattice...solidified eutectics (DSEs) have attracted considerable attention because of their thermodynamic compatibility and microstructural stability up to the

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

    PubMed

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

    2017-03-06

    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.

  18. Electronic structures of intermetallic borides RPd3Bx ( R= rare-earth metals)

    NASA Astrophysics Data System (ADS)

    Loison, C.; Leithe-Jasper, A.; Rosner, H.

    2007-05-01

    The electronic structure and the theoretical lattice parameters for the intermetallic antiperovskites RPd3B ( R from La to Yb) are calculated within the density-functional theory using the LSDA+U functional (LSDA is local spin density approximation) to include strong electronic correlations at the R site. Exemplarily, the electronic structure of LaPd3B is discussed and compared with the isoelectronic and isostructural superconductor MgCNi3 . The coherent potential approximation is applied to calculate the lattice parameters of RPd3Bx , where R=La and Lu, as a function of the boron content x . Contrarily to what was reported by Dhar [Mater. Res. Bull. 16, 1557 (1981)], a regular increase is observed in the whole range xɛ[0,1] . Moreover, the calculated lattice parameters obtained for the whole family RPd3B , with R from La to Yb, are much higher than the experimental lattice parameters published by Dhar , questioning their synthesis of stoichiometric compounds RPd3B . Attempts to synthesize RPd3B with R=La , Yb failed for LaPd3B . Instead, in the case of exposure to air, LaPd3Ox is obtained. On the contrary, YbPd3Bx could be obtained (0⩽x⩽0.6) . For this phase, the LSDA+U calculations indicate a valence instability. Thus, boron insertion in RPd3 seems eased by the tendency of the rare earth to become divalent.

  19. Scaffolding, ladders, chains, and rare ferrimagnetism in intermetallic borides: electronic structure calculations and magnetic ordering.

    PubMed

    Brgoch, Jakoah; Goerens, Christian; Fokwa, Boniface P T; Miller, Gordon J

    2011-05-04

    The electronic structures of "Ti(9-n)Fe(2+n)Ru(18)B(8)" (n=0, 0.5, 1, 2, 3), in connection to the recently synthesized Ti(9-n)Fe(2+n)Ru(18)B(8) (n=1, 2), have been investigated and analyzed using LSDA tight-binding calculations to elucidate the distribution of Fe and Ti, to determine the maximum Fe content, and to explore possible magnetic structures to interpret experimental magnetization results. Through a combination of calculations on specific models and using the rigid band approximation, which is validated by the DOS curves for "Ti(9-n)Fe(2+n)Ru(18)B(8)" (n=0, 0.5, 1, 2, 3), mixing of Fe and Ti is anticipated at both the 2b- and 4h-chain sites. The model "Ti(8.5)Fe(2.5)Ru(18)B(8)" (n=0.5) revealed that both Brewer-type Ti-Ru interactions as well as ligand field splitting of the Fe 3d orbitals regulated the observed valence electron counts between 220 and 228 electrons/formula unit. Finally, models of magnetic structures were created using "Ti(6)Fe(5)Ru(18)B(8)" (n=3). A rigid band analysis of the LSDA DOS curves concluded preferred ferromagnetic ordering at low Fe content (n≤0.75) and ferrimagnetic ordering at higher Fe content (n>0.75). Ferrimagnetism arises from antiferromagnetic exchange coupling in the scaffold of Fe1-ladder and 4h-chain sites.

  20. Superconductivity and spin fluctuations in the actinoid-platinum metal borides {Th ,U } Pt3B

    NASA Astrophysics Data System (ADS)

    Bauer, E.; Royanian, E.; Michor, H.; Sologub, O.; Scheidt, E.-W.; Gonçalves, A. P.; Bursik, J.; Wolf, W.; Reith, D.; Blaas-Schenner, C.; Moser, R.; Podloucky, R.; Rogl, P.

    2015-07-01

    Investigating the phase relations of the system {Th ,U } -Pt-B at 900 °C the formation of two compounds has been observed: cubic ThPt3B with P m 3 ¯m structure as a representative of the perovskites, and tetragonal UPt3B with P 4 m m structure being isotypic to the noncentrosymmetric structure of CePt3B . The crystal structures of the two compounds are defined by combined x-ray diffraction and transmission electron microscopy. Characterization of physical properties for ThPt3B reveals a superconducting transition at 0.75 K and an upper critical field at T =0 exceeding 0.4 T. For nonsuperconducting UPt3B a metallic resistivity behavior was found in the entire temperature range; at very low temperatures spin fluctuations become evident and the resistivity ρ (T ) follows non-Fermi liquid characteristics, ρ =ρ0+A T n with n =1.6 . Density functional theory (DFT) calculations were performed for both compounds for both types of structures. They predict that the experimentally claimed cubic structure of ThPt3B is thermodynamically not stable in comparison to a tetragonal phase, with a very large enthalpy difference of 25 kJ/mol, which cannot be explained by the formation energy of B vacancies. However, the presence of random boron vacancies possibly stabilizes the cubic structure via a local strain compensation mechanism during the growth of the crystal. For UPt3B the DFT results agree well with the experimental findings.

  1. Stress Corrosion Cracking and Oxidation Characteristics of Boride-Strengthend Microcrystalline Iron and Nickel Based Alloys.

    DTIC Science & Technology

    1984-10-22

    through subsequent thermomechanical treatments make this class of alloy attractive for many applications. One such relatively new class of alloys based...crystallizing it in the solid state) using controlled thermal or thermomechanical treatments. Preliminary evaluations of the Fe, Ni, and Co-based micrystalline...and iron in alloys 3 and 4). Each of the four microcrystalline alloys was processed in similar ways. Each alloy was induction melted and chill block

  2. Hierarchical and chemical space partitioning in new intermetallic borides MNi21B20 (M = In, Sn).

    PubMed

    Wagner, Frank R; Zheng, Qiang; Gumeniuk, Roman; Bende, David; Prots, Yurii; Bobnar, Matej; Hu, Dong-Li; Burkhardt, Ulrich; Grin, Yuri; Leithe-Jasper, Andreas

    2017-10-10

    The compounds MNi21B20 (M = In, Sn) have been synthesized and their cubic crystal structure determined (space group Pm3[combining macron]m, lattice parameters a = 7.1730(1) Å and a = 7.1834(1) Å, respectively). The structure can be described as a hierarchical partitioning of space based on a reo-e net formed by Ni3 species with large cubical, cuboctahedral and rhombicuboctahedral voids being filled according to [Ni1@Ni38], [M@Ni312], and [Ni26@B20@Ni324], respectively. The [Ni6@B20] motif inside the rhombicuboctahedral voids features an empty [Ni6] octahedron surrounded by a [B20] cage recently described in E2Ni21B20 (E = Zn, Ga). Position-space bonding analysis using ELI-D and QTAIM space partitioning as well as 2- and 3-center delocalization indices gives strong support to an alternative chemical description of space partitioning based on face-condensed [B@Ni6] trigonal prisms as basic building blocks. The shortest B-B contacts display locally nested 3-center B-B-Ni bonding inside each trigonal prism. This clearly rules out the notion of [Ni6@B20] clusters and leads to the arrangement of 20 face-condensed [B@Ni23Ni33] trigonal prisms resulting in a triple-shell like situation Ni26@B20@Ni324(reo-e), where the shells display comparable intra- and inter-shell bonding. Both compounds are Pauli paramagnets displaying metallic conductivity.

  3. Al insertion and additive effects on the thermoelectric properties of yttrium boride

    SciTech Connect

    Maruyama, Satofumi; Prytuliak, Anastasiia; Miyazaki, Yuzuru; Hayashi, Kei; Kajitani, Tsuyoshi; Mori, Takao

    2014-03-28

    The aluminoboride Y{sub x}Al{sub y}B{sub 14} (x ∼ 0.57, 0.41 ≤ y ≤ 0.63) has been found to show striking p-n control of the thermoelectric properties through variations of the y occupancy of the Al site. The effect of Al was investigated in further extremes. Polycrystalline samples of Al-free Y{sub x}B{sub 14}(x ∼ 0.55; “YB{sub 25}”) were successfully synthesized in sufficient amounts for bulk spark plasma sintering (SPS) samples and their thermoelectric properties were investigated. Y{sub 0.56}Al{sub 0.57}B{sub 14} was also prepared in comparison, and further Al was added to the samples through SPS treatment. We observed that Y{sub 0.55}B{sub 14} exhibits large positive Seebeck coefficients, ∼1000 μV K{sup −1}, around room temperature and the absolute value of the Seebeck coefficient largely decreases with increase of temperature while that of Y{sub 0.56}Al{sub 0.57}B{sub 14} is proportional to T{sup −1/2}, indicating a strong effect of Al on the electronic structure around the Fermi level. Y{sub 0.55}B{sub 14} was found to be strongly disordered with a relatively low thermal conductivity and short localization length of 0.65 Å which is close to that previously determined for the disordered and thermally glass-like compound YB{sub 66}. Occupancy of Al could not be increased further for the Al-rich sample, although Al was discovered to act as a sintering aid to enhance density and ZT could be significantly improved by 50%.

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

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

    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.

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

    DTIC Science & Technology

    1990-01-01

    and can therefore not be used as nuclear fuel because of compatibility problems with the metal clad containing the fuel and because of its very high...Refractory Carbides, Monogr. Ser. Refract. Mater., Vol. 2, Academic Press, New York, 278 p. 10. Matzke, Hj., (1986) Science of Advanced LMFBR Fuels: A

  6. Improving Hardness and Toughness of Boride Composites Based on AIMgB14

    SciTech Connect

    Peters, Justin Steven

    2007-01-01

    The search for new super-hard materials has usually focused on strongly bonded, highly symmetric crystal structures similar to diamond. The two hardest single-phase materials, diamond and cubic boron nitride (cBN), are metastable, and both must be produced at high temperatures and pressures, which makes their production costly. In 2000, a superhard composite based on a low-symmetry, boron-rich compound was reported. Since then, many advances have been made in the study of this AlMgB14-TiB2 composite. The composite has been shown to exhibit hardness greater than either of its constituent phases, relying on its sub-micron microstructure to provide hardening and strengthening mechanisms. With possible hardness around 40 GPa, an AlMgB14 - 60 vol% TiB2 approaches the hardness of cBN, yet is amenable to processing under ambient pressure conditions. There are interesting aspects of both the AlMgB14 and TiB2 phases. AlMgB14 is comprised of a framework of boron, mostly in icosahedral arrangements. It is part of a family of 12 known compounds with the same boron lattice, with the metal atoms replaced by Li, Na, Y or a number of Lanthanides. Another peculiar trait of this family of compounds is that every one contains a certain amount of intrinsic vacancies on one or both of the metal sites. These vacancies are significant, ranging from 3 to 43% of sites depending on the composition. TiB2 is a popular specialty ceramic material due to its high hardness, moderate toughness, good corrosion resistance, and high thermal and electrical conductivity. The major drawback is the difficulty of densification of pure TiB2 ceramics. A combination of sintering aids, pressure, and temperatures of 1800 C are often required to achieve near full density articles. The AlMgB14 - TiB2 composites can achieve 99% density from hot-pressing at 1400 C. This is mostly due to the preparation of powders by a high-energy milling technique known as mechanical alloying. The resulting fine powders have high activity, and Fe from wear debris acts as a sintering aid. Mechanical alloying improves the sinterability of the composite material, it has the same effect on pure TiB2. TiB2 processed by high-energy milling has been found to achieve 99% theoretical density at 1400 C with the addition of ~1 wt% Fe. Both the AlMgB14 - TiB2 composites and pure TiB2 produced from these methods have enhanced mechanical properties due to their fine microstructures. These materials show exceptional promise in the field of wear resistance. This includes cutting tools, erosion resistant coatings, and low-friction sliding contacts to name a few. Under certain wear conditions, the composite material can show performance on par with that of current high-end cBN and WC materials tailored for wear resistance. The composite material also exhibits low reactivity with Ti alloys, a pre-requisite for effective machining of these alloys, a trait that few hard materials possess.

  7. Lutetium incorporation in magmas at depth: Changes in melt local environment and the influence on partitioning behaviour

    NASA Astrophysics Data System (ADS)

    de Grouchy, Charlotte J. L.; Sanloup, Chrystèle; Cochain, Benjamin; Drewitt, James W. E.; Kono, Yoshio; Crépisson, Céline

    2017-04-01

    The structure of two Lu doped (4000 ppm) model end member silicate liquids, a highly polymerised haplogranite (Si-Al-Na-K-O) and a less polymerised anorthite-diopside (Si-Al-Mg-Ca-O), have been studied up to 8 GPa using in situ x-ray diffraction techniques. The results are the first to identify trace rare Earth element incorporation in silicate melts at high pressure. At pressures below 5 GPa, the bonding environment of Lu-O was found to be dependent on composition with coordination number CNLu-O = 8 and bond distance rLu-O = 2.36 Å in the haplogranite melt, decreasing to CNLu-O = 6 and rLu-O = 2.29 Å in the anorthite-diopside melt. This compositional variance in coordination number at low pressure is consistent with observations made for Y-O in glasses at ambient conditions and is coincident with a dramatic increase in the partition coefficients previously observed for rare Earth elements with increasing melt polymerisation. With increasing pressure we find that CNLu-O and rLu-O remain constant in the haplogranite melt. However, an abrupt change in both Lu-O coordination and bond distance is observed at 5 GPa in the anorthite-diopside melt, with CNLu-O increasing from 6 to 8-fold and rLu-O from 2.29 to 2.39 Å. This occurs over a similar pressure range where a change in the P-dependence in the reported rare Earth element partition coefficients is observed for garnet-, clinopyroxene-, and olivine-melt systems. This work shows that standard models for predicting trace elements at depth must incorporate the effect of pressure-induced structural transformations in the melt in order to realistically predict partitioning behaviour.

  8. Lanthanum(III) and Lutetium(III) in Nitrate-Based Ionic Liquids: A Theoretical Study of Their Coordination Shell.

    PubMed

    Bodo, Enrico

    2015-09-03

    By using ab initio molecular dynamics, we investigate the solvent shell structure of La(3+) and Lu(3+) ions immersed in two ionic liquids, ethylammonium nitrate (EAN) and its hydroxy derivative (2-ethanolammonium nitrate, HOEAN). We provide the first study of the coordination properties of these heavy metal ions in such a highly charged nonacqueous environment. We find, as expected, that the coordination in the liquid is mainly due to nitrate anions and that, due to the bidentate nature of the ligand, the complexation shell of the central ion has a nontrivial geometry and a coordination number in terms of nitrate molecules that apparently violates the decrease of ionic radii along the lanthanides series, since the smaller Lu(3+) ion seems to coordinate six nitrate molecules and the La(3+) ion only five. A closer inspection of the structural features obtained from our calculations shows, instead, that the first shell of oxygen atoms is more compact for Lu(3+) than for La(3+) and that the former coordinates 8 oxygen atoms while the latter 10 in accord with the typical lanthanide's trend along the series and that their first solvation shells have a slight irregular and complex geometrical pattern. When moving to the HOEAN solutions, we have found that the solvation of the central ion is possibly also due to the cation itself through the oxygen atom on the side chain. Also, in this liquid, the coordination numbers in terms of oxygen atoms in both solvents is 10 for La(3+) and 8 for Lu(3+).

  9. Electronic structure of interstitial hydrogen in lutetium oxide from DFT+U calculations and comparison study with μ SR spectroscopy

    NASA Astrophysics Data System (ADS)

    da Silva, E. Lora; Marinopoulos, A. G.; Vieira, R. B. L.; Vilão, R. C.; Alberto, H. V.; Gil, J. M.; Lichti, R. L.; Mengyan, P. W.; Baker, B. B.

    2016-07-01

    The electronic structure of hydrogen impurity in Lu2O3 was studied by first-principles calculations and muonium spectroscopy. The computational scheme was based on two methods which are well suited to treat defect calculations in f -electron systems: first, a semilocal functional of conventional density-functional theory (DFT) and secondly a DFT+U approach which accounts for the on-site correlation of the 4 f electrons via an effective Hubbard-type interaction. Three different types of stable configurations were found for hydrogen depending upon its charge state. In its negatively charged and neutral states, hydrogen favors interstitial configurations residing either at the unoccupied sites of the oxygen sublattice or at the empty cube centers surrounded by the lanthanide ions. In contrast, the positively charged state stabilized only as a bond configuration, where hydrogen binds to oxygen ions. Overall, the results between the two methods agree in the ordering of the formation energies of the different impurity configurations, though within DFT+U the charge-transition (electrical) levels are found at Fermi-level positions with higher energies. Both methods predict that hydrogen is an amphoteric defect in Lu2O3 if the lowest-energy configurations are used to obtain the charge-transition, thermodynamic levels. The calculations of hyperfine constants for the neutral interstitial configurations show a predominantly isotropic hyperfine interaction with two distinct values of 926 MHz and 1061 MHz for the Fermi-contact term originating from the two corresponding interstitial positions of hydrogen in the lattice. These high values are consistent with the muonium spectroscopy measurements which also reveal a strongly isotropic hyperfine signature for the neutral muonium fraction with a magnitude slightly larger (1130 MHz) from the ab initio results (after scaling with the magnetic moments of the respective nuclei).

  10. EF5 and Motexafin Lutetium in Detecting Tumor Cells in Patients With Abdominal or Non-Small Cell Lung Cancer

    ClinicalTrials.gov

    2013-01-15

    Advanced Adult Primary Liver Cancer; Carcinoma of the Appendix; Fallopian Tube Cancer; Gastrointestinal Stromal Tumor; Localized Extrahepatic Bile Duct Cancer; Localized Gallbladder Cancer; Localized Gastrointestinal Carcinoid Tumor; Localized Resectable Adult Primary Liver Cancer; Localized Unresectable Adult Primary Liver Cancer; Metastatic Gastrointestinal Carcinoid Tumor; Ovarian Sarcoma; Ovarian Stromal Cancer; Primary Peritoneal Cavity Cancer; Recurrent Adult Primary Liver Cancer; Recurrent Adult Soft Tissue Sarcoma; Recurrent Colon Cancer; Recurrent Extrahepatic Bile Duct Cancer; Recurrent Gallbladder Cancer; Recurrent Gastric Cancer; Recurrent Gastrointestinal Carcinoid Tumor; Recurrent Non-small Cell Lung Cancer; Recurrent Ovarian Epithelial Cancer; Recurrent Ovarian Germ Cell Tumor; Recurrent Pancreatic Cancer; Recurrent Rectal Cancer; Recurrent Small Intestine Cancer; Recurrent Uterine Sarcoma; Regional Gastrointestinal Carcinoid Tumor; Small Intestine Adenocarcinoma; Small Intestine Leiomyosarcoma; Small Intestine Lymphoma; Stage 0 Non-small Cell Lung Cancer; Stage I Adult Soft Tissue Sarcoma; Stage I Colon Cancer; Stage I Gastric Cancer; Stage I Non-small Cell Lung Cancer; Stage I Ovarian Epithelial Cancer; Stage I Ovarian Germ Cell Tumor; Stage I Pancreatic Cancer; Stage I Rectal Cancer; Stage I Uterine Sarcoma; Stage II Adult Soft Tissue Sarcoma; Stage II Colon Cancer; Stage II Gastric Cancer; Stage II Non-small Cell Lung Cancer; Stage II Ovarian Epithelial Cancer; Stage II Ovarian Germ Cell Tumor; Stage II Pancreatic Cancer; Stage II Rectal Cancer; Stage II Uterine Sarcoma; Stage III Adult Soft Tissue Sarcoma; Stage III Colon Cancer; Stage III Gastric Cancer; Stage III Ovarian Epithelial Cancer; Stage III Ovarian Germ Cell Tumor; Stage III Pancreatic Cancer; Stage III Rectal Cancer; Stage III Uterine Sarcoma; Stage IIIA Non-small Cell Lung Cancer; Stage IIIB Non-small Cell Lung Cancer; Stage IV Adult Soft Tissue Sarcoma; Stage IV Colon Cancer; Stage IV Gastric Cancer; Stage IV Non-small Cell Lung Cancer; Stage IV Ovarian Epithelial Cancer; Stage IV Ovarian Germ Cell Tumor; Stage IV Pancreatic Cancer; Stage IV Rectal Cancer; Stage IV Uterine Sarcoma; Unresectable Extrahepatic Bile Duct Cancer; Unresectable Gallbladder Cancer

  11. Estimation of Whole Body Radiation Exposure to Nuclear Medicine Personnel During Synthesis of (177)Lutetium-labeled Radiopharmaceuticals.

    PubMed

    Arora, Geetanjali; Mishra, Rajesh; Kumar, Praveen; Yadav, Madhav; Ballal, Sanjana; Bal, Chandrasekhar; Damle, Nishikant Avinash

    2017-01-01

    With rapid development in the field of nuclear medicine therapy, radiation safety of the personnel involved in synthesis of radiopharmaceuticals has become imperative. Few studies have been done on estimating the radiation exposure of personnel involved in the radio labeling of (177)Lu-compounds in western countries. However, data from the Indian subcontinent are limited. We have estimated whole body radiation exposure to the radiopharmacist involved in the labeling of: (177)Lu-DOTATATE, (177)Lu-PSMA-617, and (177)Lu-EDTMP. Background radiation was measured by keeping a pocket dosimeter around the workbench when no radioactive work was conducted. The same pocket dosimeter was given to the radiopharmacist performing the labeling of (177)Lu-compounds. All radiopharmaceuticals were synthesized by the same radiopharmacist with 3, 1 and 3 year experience, respectively, in radiolabeling the above compounds. One Curie (1 Ci) of (177)Lu was received fortnightly by our department. Data were collected for 12 syntheses of (177)Lu-DOTATATE, 8 syntheses of (177)Lu-PSMA-617, and 3 syntheses of (177)Lu-EDTMP. Mean time required to complete the synthesis was 0.81, 0.65, and 0.58 h, respectively. Mean whole body radiation exposure was 0.023 ± 0.01 mSv, 0.01 ± 0.002 mSv, and 0.002 ± 0.0006 mSv, respectively. Overall mean radiation dose for all the three (177)Lu-compounds was 0.014 mSv. Highest exposure was obtained during the synthesis of (177)Lu-DOTATATE. Our data suggest that the manual radiolabeling of (177)Lu compounds is safe, and the whole body radiation exposure to the involved personnel is well within prescribed limits.

  12. NEW ABUNDANCE DETERMINATIONS OF CADMIUM, LUTETIUM, AND OSMIUM IN THE r-PROCESS ENRICHED STAR BD +17 3248 {sup ,}

    SciTech Connect

    Roederer, Ian U.; Sneden, Christopher; Lawler, James E.; Cowan, John J.

    2010-05-01

    We report the detection of Cd I (Z = 48), Lu II (Z = 71), and Os II (Z = 76) in the metal-poor star BD +17 3248. These abundances are derived from an ultraviolet spectrum obtained with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. This is the first detection of these neutron-capture species in a metal-poor star enriched by the r process. We supplement these measurements with new abundances of Mo I, Ru I, and Rh I derived from an optical spectrum obtained with the High Resolution Echelle Spectrograph on Keck. Combined with previous abundance derivations, 32 neutron-capture elements have been detected in BD +17 3248, the most complete neutron-capture abundance pattern in any metal-poor star to date. The light neutron-capture elements (38 {<=} Z {<=} 48) show a more pronounced even-odd effect than expected from current solar system r-process abundance predictions. The age for BD +17 3248 derived from the Th II/Os II chronometer is in better agreement with the age derived from other chronometers than the age derived from Th II/Os I. New Hf II abundance derivations from transitions in the ultraviolet are lower than those derived from transitions in the optical, and the lower Hf abundance is in better agreement with the scaled solar system r-process distribution.

  13. Extraction of lutetium(III) from aqueous solutions by employing a single fibre-supported liquid membrane.

    PubMed

    Trtić-Petrović, Tatjana M; Kumrić, Ksenija R; Dordević, Jelena S; Vladisavljević, Goran T

    2010-07-01

    Transport behaviour of Lu(III) across a polypropylene hollow fibre-supported liquid membrane containing di(2-ethylhexyl)phosphoric acid (DEHPA) in dihexyl ether as a carrier has been studied. The donor phase was LuCl(3) in the buffer solution consisting of 0.2 M sodium acetate at pH 2.5-5.0. A miniaturised system with a single hollow fibre has been operated in a batch mode. The concentration of Lu(III) was determined by indirect voltammetric method using Zn-EDTA complex. The effect of pH and volume of the donor phase, DEHPA concentration in the organic (liquid membrane) phase, the time of extraction and the content of the acceptor phase on the Lu(III) extraction and stripping behaviour was investigated. The results were discussed in terms of the pertraction and removal efficiency, the memory effect and the mean flux of Lu(III). The optimal conditions for the removal of (177)Lu(III) from labelled (177)Lu-radiopharmaceuticals were discussed and identified. The removal efficiency of Lu(III) greater than 99% was achieved at pH of the donor phase between 3.5 and 5.0 using DEHPA concentration in the organic phase of 0.47 M and the ratio of the donor to the acceptor phase of 182.

  14. Multiple Electron Charge Transfer Chemistries for Electrochemical Energy Storage Systems: The Metal Boride and Metal Air Battery

    NASA Astrophysics Data System (ADS)

    Stuart, Jessica F.

    The primary focus of this work has been to develop high-energy capacity batteries capable of undergoing multiple electron charge transfer redox reactions to address the growing demand for improved electrical energy storage systems that can be applied to a range of applications. As the levels of carbon dioxide (CO2) increase in the Earth's atmosphere, the effects on climate change become increasingly apparent. According to the Energy Information Administration (EIA), the U.S. electric power sector is responsible for the release of 2,039 million metric tons of CO2 annually, equating to 39% of total U.S. energy-related CO2 emissions. Both nationally and abroad, there are numerous issues associated with the generation and use of electricity aside from the overwhelming dependence on fossil fuels and the subsequent carbon emissions, including reliability of the grid and the utilization of renewable energies. Renewable energy makes up a relatively small portion of total energy contributions worldwide, accounting for only 13% of the 3,955 billion kilowatt-hours of electricity produced each year, as reported by the EIA. As the demand to reduce our dependence on fossils fuels and transition to renewable energy sources increases, cost effective large-scale electrical energy storage must be established for renewable energy to become a sustainable option for the future. A high capacity energy storage system capable of leveling the intermittent nature of energy sources such as solar, wind, and water into the electric grid and provide electricity at times of high demand will facilitate this transition. In 2008, the Licht Group presented the highest volumetric energy capacity battery, the vanadium diboride (VB2) air battery, exceedingly proficient in transferring eleven electrons per molecule. This body of work focuses on new developments to this early battery such as fundamentally understanding the net discharge mechanism of the system, evaluation of the properties and performance of nanoscopic anodic materials in addition to the previously developed macroscopic system, as well as the exploration of a high-energy capacity TiB 2/VB2 composite anode. However, the greatest challenge to this room temperature VB2 primary battery is to develop a means to electrochemically recharge the anodic material (how to reinsert the eleven electrons per molecule that are removed during the battery's discharge). Rechargeable batteries, such as the new molten air battery presented in this thesis, offer a high intrinsic capacity mode for energy storage and overcome problems such as the need for higher energy capacity, cost-effective batteries for a range of electronic, transportation, and large-scale power storage devices. Molten air batteries presented and discussed in this work are viable systems that provide a means to electrochemically recharge the VB2-air battery and deliver large-scale energy storage due to their scalability, location flexibility, construction from readily available resources, and offer increased energy storage capacity for the electric grid. One example is the VB2 molten air battery, which discharges according to: VB 2 + 11/4 O2 → 1/ 2 V2O5 + B2O3 (1). Previously, our group has shown that carbon dioxide can be captured from atmospheric air concentrations at solar efficiencies as high as 50%, and that carbon dioxide emissions associated with the production of several commodities can be electrochemically avoided in by the Solar Thermal Electrochemical Process (STEP). Utilizing this process, the carbon molten air battery relies on carbon dioxide directly from the air: Charging: CO2 (g) → C (solid) + O2 (g) (2) Discharging: C (solid) + O2 (g) → CO2 (g) (3). More specifically, in a molten carbonate electrolyte containing added oxide, such as lithium carbonate with lithium oxide, the four-electron charging reaction, Equation 2, approaches 100% faradic efficiency and can be described as the following two equations: O2- (dissolved) + CO2 (g) → CO 32- (molten) (2a) CO32- (molten) ?→ C (solid) + O2 (g) + O2- (dissolved) (2b). Thus, powered by the oxidation of carbon formed directly from the CO 2 in our earth's atmosphere, the carbon molten air battery is a viable system to provide large-scale energy storage. These batteries are rechargeable and have amongst the highest intrinsic battery storage capacities available. The electron charge transfer chemistry is demonstrated through three examples. These examples utilize iron, carbon, and vanadium diboride as reactive materials, each containing intrinsic volumetric energy capacities of 10,000 Wh/L for Fe to Fe (III), 19,000 Wh/L for C to CO2, and 27,000 Wh/L for VB2 to B2O3 and V2O 5, compared to 6,200 Wh/L for the lithium air battery.

  15. Origin of the anisotropic upper critical fields in single crystals of superconducting rare-earth ternary borides

    SciTech Connect

    Shenoy, G.K.; Malik, S.K.

    1986-05-01

    Upper-critical-field (H/sub c/2(T)) measurements in single-crystal ErRh/sub 4/B/sub 4/ have revealed a large anisotropy. We show that this anisotropy is a consequence of the crystalline electric fields (CEF's) acting on the Er/sup 3 +/ ion which make the exchange field acting on the conduction electrons anisotropic. A full calculation based on Werthamer-Helfand-Hohenberg theory with the inclusion of CEF's completely explains the observed anisotropy in H/sub c/2(T) for ErRh/sub 4/B/sub 4/. In addition, the critical-field measurements in ErRh/sub 4/B/sub 4/ provide a means for the reliable determination of the magnitude and the sign of the exchange constant J/sub s/f.

  16. Modification of Structure and Properties of Titanium Surfaces During Formation of Silicides and Borides Initiated by High-Energy Treatment

    NASA Astrophysics Data System (ADS)

    Potekaev, A. I.; Klopotov, A. A.; Ivanov, Yu. F.; Volokitin, O. G.

    2013-12-01

    An analysis of binary (Ti-Si, Ti-В, Si-B) and ternary (Ti-Si-B) phase states is made, their diagrams are presented, and a possibility for formation of a large number of metastable compounds is revealed. The latter are found to form as a result of application of non-equilibrium conditions in the course of material treatment with concentrated high-energy flows. Using an x-ray diffraction analysis and electron-diffraction microscopy, the phase composition of the surface layer of technical-grade titanium (VT1-0) treated by concentrated energy flows (irradiation with plasma from electrical wire explosion and high-intensity pulsed electron beam) is investigated.

  17. Doping experiments on low-dimensional oxides and a search for unusual magnetic properties of magnesium aluminum boride

    NASA Astrophysics Data System (ADS)

    Hill, Julienne Marie

    Doping experiments on La2CuO4, Sr2CuO 3 and SrCu2(BO3)2 were performed with the intent of synthesizing new metallic low-dimensional cuprate oxide compounds. Magnetic susceptibility chi(T) measurements on a polycrystalline La 2CuO4 sample chemically oxidized at room temperature in aqueous NaClO showed superconductivity with a superconducting transition temperature Tc of 42.6 K and a Meissner fraction of 26%. We were unable to electrochemically oxidize La2CuO4 in a nonaqueous solution of tetramethylammonium hydroxide (TMAOH) and methanol. Sr2CuO 3 was found to decompose upon exposure to air and water. Electron paramagnetic resonance, isothermal magnetization M(H) and chi(T) measurements on the primary decomposition product, Sr2Cu(OH)6, were consistent with a nearly isolated, spin S = 1/2, local moment model for the Cu +2 spins. From a fit of chi(T) by the Curie-Weiss law and of the M(H) isotherms by a modified Brillouin function, the weakly antiferromagnetic exchange interaction between adjacent Cu+2 spins in Sr 2Cu(OH)6 was found to be J/kB = 1.06(4) K. Doping studies on SrCu2(BO3)2 were inconclusive. chi(T) measurements on an undoped polycrystalline sample of SrCu2(BO 3)2, a sample treated with distilled water, and a sample treated with aqueous NaClO showed no qualitative differences between the samples. In addition, chi(T) and M(H, T) studies of the ultra-hard material MgAlB14 were carried out in search of superconductivity or ferromagnetism in this compound. chi(T) measurements on a powder sample revealed temperature-independent diamagnetism from 1.8 K up to room temperature with a Curie-Weiss impurity concentration equivalent to ˜1 mol% of spin-1/2 ions. In contrast, M(H, T) data on hot pressed samples showed evidence of ferromagnetic transitions above ˜330 K. Scanning electron microscopy and Auger microprobe analysis of the hot pressed samples indicated that the observed ferromagnetism was likely due to Fe impurities.

  18. Enhanced Erosion Protection of TWAS Coated Ti6Al4V Alloy Using Boride Bond Coat and Subsequent Laser Treatment

    NASA Astrophysics Data System (ADS)

    Mann, B. S.; Arya, Vivek; Pant, B. K.

    2011-08-01

    The material commonly used in low-pressure high-rating super critical/ultra super critical steam turbines as well as guide and moving blades of high speed aero compressors is Ti6Al4V alloy. These blades are severely affected owing to erosion which leads to drop in efficiency and increase in maintenance cost. This article deals with SHS 7170 coating on Ti6Al4V alloy using twin wire arc spraying (TWAS), enhancing its bonding by providing a thin bond coat and then treating with high-power diode laser (HPDL). Significant improvement in erosion resistance of this multilayer coating has been achieved because of the formation of fine-grained micro structure due to rapid heating and cooling rates associated with the laser surface treatment. After laser surface treatment, the fracture toughness of this multilayer has improved manifold. The water droplet and particulate erosion test results along with the damage mechanism are reported and discussed in this article.

  19. Synthesis, Radiolabelling and In Vitro Characterization of the Gallium-68-, Yttrium-90- and Lutetium-177-Labelled PSMA Ligand, CHX-A''-DTPA-DUPA-Pep.

    PubMed

    Baur, Benjamin; Solbach, Christoph; Andreolli, Elena; Winter, Gordon; Machulla, Hans-Jürgen; Reske, Sven N

    2014-04-29

    Since prostate-specific membrane antigen (PSMA) has been identified as a diagnostic target for prostate cancer, many urea-based small PSMA-targeting molecules were developed. First, the clinical application of these Ga-68 labelled compounds in positron emission tomography (PET) showed their diagnostic potential. Besides, the therapy of prostate cancer is a demanding field, and the use of radiometals with PSMA bearing ligands is a valid approach. In this work, we describe the synthesis of a new PSMA ligand, CHX-A''-DTPA-DUPA-Pep, the subsequent labelling with Ga-68, Lu-177 and Y-90 and the first in vitro characterization. In cell investigations with PSMA-positive LNCaP C4-2 cells, KD values of ≤14.67 ± 1.95 nM were determined, indicating high biological activities towards PSMA. Radiosyntheses with Ga-68, Lu-177 and Y-90 were developed under mild reaction conditions (room temperature, moderate pH of 5.5 and 7.4, respectively) and resulted in nearly quantitative radiochemical yields within 5 min.

  20. Modeled Neutron Induced Nuclear Reaction Cross Sections for Radiochemsitry in the region of Thulium, Lutetium, and Tantalum I. Results of Built in Spherical Symmetry in a Deformed Region

    SciTech Connect

    Hoffman, R. D.

    2013-09-06

    We have developed a set of modeled nuclear reaction cross sections for use in radiochemical diagnostics. Systematics for the input parameters required by the Hauser-Feshbach statistical model were developed and used to calculate neutron induced nuclear reaction cross sections for targets ranging from Terbium (Z = 65) to Rhenium (Z = 75). Of particular interest are the cross sections on Tm, Lu, and Ta including reactions on isomeric targets.

  1. Studies on the Labeling of Ethylenediaminetetramethylene Phosphonic Acid, Methylene Diphosphonate, Sodium Pyrophosphate and Hydroxyapatite with Lutetium-177 for use in Nuclear Medicine

    PubMed Central

    Abbasi, Imtiaz Ahmed

    2015-01-01

    For the treatment of skeletal metastasis, a therapeutic radionuclide tagged with a bone seeking ligand is required, while for radiation synovectomy (RS), a therapeutic radionuclide irreversibly attached to pre-formed particles of appropriate size is required. Radio lanthanides are mostly therapeutic, and ligands containing phosphate groups are predominantly bone seekers. Exploiting these facts, number of new therapeutic radiopharmaceuticals could be developed. Labeling of four phosphate containing materials was pursued in the present study. It was hypothesized that various 177Lu-labeled bone-seeking complexes such as 177Lu-ethylenediaminetetramethylene phosphonic acid (EDTMP), 177Lu-methylene diphosphonate (MDP) and 177Lu-pyrophosphate (PYP) could be developed as agents for palliative radiotherapy of bone pain due to skeletal metastases, and 177Lu-Hydroxyapatite (HA) could be developed as an agent for radiosynovectomy of small joints. Lyophilized kit vials of EDTMP, MDP and sodium pyrophosphate (Na-PYP) were formulated. HA particles were synthesized locally and purity was checked by high-performance liquid chromatography (HPLC). 177Lu was labeled with EDTMP, MDP, PYP, and HA and the behavior of all was studied by radio-thin layer chromatography (TLC) radio-HPLC and radio-electrophoresis. Radio-TLC confirmed the labeling. HPLC analysis too verified the labeling. Radio-electrophoresis results depicted peaks for 177Lu-MDP, 177Lu-EDTMP and 177Lu-PYP at 3.37 ± 0.06 cm, 5.53 ± 0.15 cm and 7.03 ± 0.06 cm respectively confirming negative charge on each specie as all migrated toward positive anode. All 3 methods verified the labeling. The study demonstrated that EDTMP, MDP and PYP form stable complexes with 177Lu in injectable solution form. HA particulates could too be labeled with 177Lu with high radiochemical yields (>98%) in suspension form. Former three could be utilized as bone-pain palliation agents for the treatment of bone metastases, and the later could be applied for the treatment of Rheumatoid arthritis of small joints. The study has also indicated the possibility of developing other numerous radiolanthanide analogs with the potentials of possible use in radiation therapy. PMID:26097419

  2. Nuclear magnetic resonance and potentiometric studies of the protonation scheme of a triaza triacetic macrocycle and its complexes with lanthanum and lutetium

    SciTech Connect

    Geraldes, C.F.G.C.; Alpoim, M.C.; Marques, M.P.M.; Sherry, A.D.; Singh, M.

    1985-11-06

    The protonation constants of the macrocyclic ligand 1,4,7-triazacyclononane-N,N',N''-triacetic acid (NOTA) have been measured by potentiometry, and the protonation sequence of the various amino and carboxylate groups of NOTA has been studied in D/sub 2/O as a function of pD from the chemical shifts of the nonlabile protons. Shielding constants for protonation of the amino groups were determined in a NMR study of the triaza macrocyclic amine, its trimethylated analogue, and NOTA and compared with values reported for linear polyamino polycarboxylates and cyclic tetraaza tetracarboxylate ligands. The results indicate that two nitrogens of NOTA are protonated at higher pH than the carboxylate groups. The last nitrogen is protonated only at very low pH. The sequence of protonation of NOTA supports the formation of hydrogen bonds between two protonated nitrogens and the adjacent two nonprotonated carboxylates. The /sup 1/H and /sup 13/C spectra of the La(NOTA) and Lu(NOTA) species were studied as a function of pH and temperature. 33 references, 5 figures, 4 tables.

  3. Discrete zero-phonon Cr3+ lines in the spectra of Terbium-Yttrium-Lutetium Aluminum garnets solid solutions: Lattice compression and dilation

    NASA Astrophysics Data System (ADS)

    Feofilov, S. P.; Kulinkin, A. B.; Ovanesyan, K. L.; Petrosyan, A. G.

    2016-01-01

    The zero-phonon electronic transitions in Cr3+ impurity ions in a series of Tb3zY3-3zAl5O12 (0

  4. Studies on the Labeling of Ethylenediaminetetramethylene Phosphonic Acid, Methylene Diphosphonate, Sodium Pyrophosphate and Hydroxyapatite with Lutetium-177 for use in Nuclear Medicine.

    PubMed

    Abbasi, Imtiaz Ahmed

    2015-01-01

    For the treatment of skeletal metastasis, a therapeutic radionuclide tagged with a bone seeking ligand is required, while for radiation synovectomy (RS), a therapeutic radionuclide irreversibly attached to pre-formed particles of appropriate size is required. Radio lanthanides are mostly therapeutic, and ligands containing phosphate groups are predominantly bone seekers. Exploiting these facts, number of new therapeutic radiopharmaceuticals could be developed. Labeling of four phosphate containing materials was pursued in the present study. It was hypothesized that various (177)Lu-labeled bone-seeking complexes such as (177)Lu-ethylenediaminetetramethylene phosphonic acid (EDTMP), (177)Lu-methylene diphosphonate (MDP) and (177)Lu-pyrophosphate (PYP) could be developed as agents for palliative radiotherapy of bone pain due to skeletal metastases, and (177)Lu-Hydroxyapatite (HA) could be developed as an agent for radiosynovectomy of small joints. Lyophilized kit vials of EDTMP, MDP and sodium pyrophosphate (Na-PYP) were formulated. HA particles were synthesized locally and purity was checked by high-performance liquid chromatography (HPLC). (177)Lu was labeled with EDTMP, MDP, PYP, and HA and the behavior of all was studied by radio-thin layer chromatography (TLC) radio-HPLC and radio-electrophoresis. Radio-TLC confirmed the labeling. HPLC analysis too verified the labeling. Radio-electrophoresis results depicted peaks for (177)Lu-MDP, (177)Lu-EDTMP and (177)Lu-PYP at 3.37 ± 0.06 cm, 5.53 ± 0.15 cm and 7.03 ± 0.06 cm respectively confirming negative charge on each specie as all migrated toward positive anode. All 3 methods verified the labeling. The study demonstrated that EDTMP, MDP and PYP form stable complexes with (177)Lu in injectable solution form. HA particulates could too be labeled with (177)Lu with high radiochemical yields (>98%) in suspension form. Former three could be utilized as bone-pain palliation agents for the treatment of bone metastases, and the later could be applied for the treatment of Rheumatoid arthritis of small joints. The study has also indicated the possibility of developing other numerous radiolanthanide analogs with the potentials of possible use in radiation therapy.

  5. The Z2/A Dependence in Heavy-Ion Fusion for the Reactions of Chlorine on Thulium, Lutetium, Tantalum and Tungsten.

    DTIC Science & Technology

    1980-06-01

    8217. ci . . a - C-7 .?inal Report 7MaY 1980 - -Tantalum and Tungs ten 6. PERFORMING ORG. REPORT NUMBER 7. AUTNORre) S. CONTRACT OR GRANT NUMBER(a) Anthony C...Residue Cross Sections in ib ....................................... 37 111 35 ci + 169 Tm Parent and Total Absolute Evaporation Residue Cross Sections...V 37 ci + 181 Ta Parent and Total Absolute Evaporation Residue Cross Sections................................ 121 VI 37c C1 186 W Parent and Total

  6. The Case for and against a D-Wave Pairing State in the High Temperature Superconductor Lutetium BARIUM(2) COPPER(3) OXYGEN(7-DELTA)

    NASA Astrophysics Data System (ADS)

    Buan, John Stuart

    1995-01-01

    The nature of the pairing state of the high-temperature superconductor, LuBa_2Cu _3O_{7-delta} , has been investigated. The work was performed on a high-quality single crystal of the material obtained from the University of California, Davis. The study involved two phases, characterization of the crystal quality, which includes x-ray diffraction measurements, specific heat measurements near T_{rm c} and low-field magnetization measurements, and pairing state experiments, including measurements of the low temperature specific heat, the anisotropic specific heat near T _{rm c} and the anisotropic transverse magnetization. The anisotropic specific heat near the transition is defined as follows:{{int limits_sp{rm T_1}{ rm T_2}}rm dT[ C _{p}(H_{b} = 6T)-C_ {p}(H_{a} = 6T)]/T over{intlimits_sp{rm T_1}{rm T_2}}rm dT[ C_{p}(H = 0T)-C_ {p}(H_{a} = 6T)]/T }with subscripts 'a' and 'b' referring to the respective crystallographic axes. The data were taken using a well-established ac calorimetric technique. The results indicate a role for the CuO chains in the superconductivity present in the 123 system. The implications of this fact for the pairing state theories are discussed. The anisotropic transverse magnetic magnetization was also measured. Using a commercial DC SQUID susceptometer and a custom made sample rotation stage, the magnetization was measured at an angle perpendicular to the magnetic field vector, as a function of angle in the basal plane, with the field applied in the a-b plane of the crystal. The results of this experiment when performed on a "d"-wave superconductor have been predicted. The results of this work are examined in the context of the earlier theoretical work.

  7. Etudes optiques de nouveaux materiaux laser: Des orthosilicates dopes a l'ytterbium: Le yttrium (lutetium,scandium) pentoxide de silicium

    NASA Astrophysics Data System (ADS)

    Denoyer, Aurelie

    La decouverte et l'elaboration de nouveaux materiaux laser solides suscitent beaucoup d'interet parmi la communaute scientifique. En particulier les lasers dans la gamme de frequence du micron debouchent sur beaucoup d'applications, en telecommunication, en medecine, dans le domaine militaire, pour la, decoupe des metaux (lasers de puissance), en optique non lineaire (doublage de frequence, bistabilite optique). Le plus couramment utilise actuellement est le Nd:YAG dans cette famille de laser, mais des remplacants plus performants sont toujours recherches. Les lasers a base d'Yb3+ possedent beaucoup d'avantages compares aux lasers Nd3+ du fait de leur structure electronique simple et de leur deterioration moins rapide. Parmi les matrices cristallines pouvant accueillir l'ytterbium, les orthosilicates Yb:Y 2SiO5, Yb:Lu2SiO5 et Yb:Sc2SiO 5 se positionnent tres bien, du fait de leur bonne conductivite thermique et du fort eclatement de leur champ cristallin necessaire a l'elaboration de lasers quasi-3 niveaux. De plus l'etude fine et systematique des proprietes microscopiques de nouveaux materiaux s'avere toujours tres interessante du point de vue de la recherche fondamentale, c'est ainsi que de nouveaux modeles sont concus (par exemple pour le champ cristallin) ou que de nouvelles proprietes inhabituelles sont decouvertes, menant a de nouvelles applications. Ainsi d'autres materiaux dopes a l'ytterbium sont connus pour leurs proprietes de couplage electron-phonon, de couplage magnetique, d'emission cooperative ou encore de bistabilite optique, mais ces proprietes n'ont encore jamais ete mises en evidence dans Yb:Y 2SiO5, Yb:Lu2SiO5 et Yb:Sc2SiO 5. Ainsi, cette these a pour but l'etude des proprietes optiques et des interactions microscopiques dans Yb:Y2SiO 5, Yb:Lu2SiO5 et Yb:Sc2SiO5. Nous utilisons principalement les techniques d'absorption IR et de spectroscopie Raman pour determiner les excitations du champ cristallin et les modes de vibration dans le materiau. Des mesures optiques sous champ magnetique ont egalement ete effectuees dans le but de caracteriser le comportement de ces excitations lorsqu'elles sont soumises a l'effet Zeeman. La resonance paramagnetique electronique a permis de completer cette etude de l'eclatement Zeeman suivant toutes les orientations du cristal. Enfin la fluorescence par excitation selective et la fluorescence induite par Raman FT, completent la description des niveaux d'energie et revelent l'existence d'emission cooperative de deux ions Yb3+ et de transferts d'energie. Les resultats de cette these apportent une contribution originale dans le domaine des nouveaux materiaux lasers par l'etude et la comprehension des interactions fines et des proprietes microscopiques d'un materiau en particulier. Ils debouchent a la fois sur des applications possibles dans le domaine de l'optique et des lasers, et sur la comprehension d'aspects fondamentaux. Cette these a prouve l'interet de ces matrices pour leur utilisation comme lasers solides: un fort eclatement du champ cristallin favorable a l'elaboration de laser quasi-3 niveaux, et de larges bandes d'absorption (dues a un fort couplage electron-phonon et a des raies satellites causees par une interaction d'echange entre deux ions Yb3+) qui permettent la generation d'impulsions laser ultra-courtes, l'accordabilite du laser, etc. De plus la miniaturisation des lasers est possible pour l'optique integree grace a des couches minces synthetisees par epitaxie en phase liquide dont nous avons demontre la tres bonne qualite structurale et l'ajustement possible de certains parametres. Nous avons reconstruit le tenseur g du niveau fondamental (qui donne des informations precieuses sur les fonctions d'onde), ceci dans le but d'aider les theoriciens a concevoir un modele de champ cristallin valide. Plusieurs mecanismes de transferts d'energie ont ete mis en evidence: un mecanisme de relaxation d'un site vers l'autre, un mecanisme d'emission cooperative, et un mecanisme d'excitation de l'Yb3+ par le Tm3+ (impurete presente dans le materiau). Ces transferts sont plutot nefastes pour la fabrication d'un laser mais sont interessants pour l'optique non lineaire (doublage de frequence, memoires optiques). Enfin, plusieurs elements (le couplage magnetique de paire, le couplage electron-phonon et l'emission cooperative) nous ont permis de conclure sur le caractere covalent de la matrice. Nous avons d'ailleurs demontre ici le role de la covalence dans l'emission cooperative, transition habituellement attribuee aux interactions multipolaires electriques.

  8. Single-Dose Anti-CD138 Radioimmunotherapy: Bismuth-213 is More Efficient than Lutetium-177 for Treatment of Multiple Myeloma in a Preclinical Model.

    PubMed

    Fichou, Nolwenn; Gouard, Sébastien; Maurel, Catherine; Barbet, Jacques; Ferrer, Ludovic; Morgenstern, Alfred; Bruchertseifer, Frank; Faivre-Chauvet, Alain; Bigot-Corbel, Edith; Davodeau, François; Gaschet, Joëlle; Chérel, Michel

    2015-01-01

    Radioimmunotherapy (RIT) has emerged as a potential treatment option for multiple myeloma (MM). In humans, a dosimetry study recently showed the relevance of RIT using an antibody targeting the CD138 antigen. The therapeutic efficacy of RIT using an anti-CD138 antibody coupled to (213)Bi, an α-emitter, was also demonstrated in a preclinical MM model. Since then, RIT with β-emitters has shown efficacy in treating hematologic cancer. In this paper, we investigate the therapeutic efficacy of RIT in the 5T33 murine MM model using a new anti-CD138 monoclonal antibody labeled either with (213)Bi for α-RIT or (177)Lu for β-RIT. A new monoclonal anti-CD138 antibody, 9E7.4, was generated by immunizing a rat with a murine CD138-derived peptide. Antibody specificity was validated by flow cytometry, biodistribution, and α-RIT studies. Then, a β-RIT dose-escalation assay with the (177)Lu-radiolabeled 9E7.4 mAb was performed in KalwRij C57/BL6 mice 10 days after i.v. engraftment with 5T33 MM cells. Animal survival and toxicological parameters were assessed to define the optimal activity. α-RIT performed with 3.7 MBq of (213)Bi-labeled 9E7.4 anti-CD138 mAb increased median survival to 80 days compared to 37 days for the untreated control and effected cure in 45% of animals. β-RIT performed with 18.5 MBq of (177)Lu-labeled 9E7.4 mAb was well tolerated and significantly increased mouse survival (54 vs. 37 days in the control group); however, no mice were cured with this treatment. This study revealed the advantages of α-RIT in the treatment of MM in a preclinical model where β-RIT shows almost no efficacy.

  9. Peptide receptor radionuclide therapy of Merkel cell carcinoma using (177)lutetium-labeled somatostatin analogs in combination with radiosensitizing chemotherapy: a potential novel treatment based on molecular pathology.

    PubMed

    Salavati, Ali; Prasad, Vikas; Schneider, Claus-Peter; Herbst, Rudolf; Baum, Richard Paul

    2012-05-01

    Few studies have been published on the safety and feasibility of synchronous use of peptide receptor radionuclide therapy (PRRNT), as source of internal radiation therapy, in combination with chemotherapy. In this study we reported a 53-year-old man with stage IV Merkel cell carcinoma (MCC), who underwent synchronous internal radiation therapy and chemotherapy. Based on presumable poor prognosis with chemotherapy only, functional similarities of MCC with other neuroendocrine tumors and available evidence of effectiveness and safety of synchronous use of external beam radiation therapy and chemotherapy in treatment of high-risk MCC patients, our interdisciplinary neuroendocrine tumor board recommended him to add PRRNT to his ongoing chemotherapy. He received 2 courses of (177)Lu-DOTATATE(1, 4, 7, 10-Tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid-1-D-Phe1-Tyr3-Thr8-octreotide) in combination with ongoing 8 cycles of liposomal doxorubicin based on standard protocols. Response to therapy was evaluated by (18)F-FDG and (68)gallium-somatostatin-receptor PET/CT. There was an impressive improvement of the clinical symptoms. However, follow-up PET/CT studies showed mixed pattern of response. Synchronous use of PRRNT and radiosensitizing chemotherapy seems safe and feasible in high risk MCC patients, however, further prospective studies and clinical trials are warranted to provide reliable evidence of possible pitfalls and effectiveness of PRRNT and (68)Ga-somatostatin-receptor PET/CT in the management of MCC.

  10. Anti-L1CAM radioimmunotherapy is more effective with the radiolanthanide terbium-161 compared to lutetium-177 in an ovarian cancer model.

    PubMed

    Grünberg, Jürgen; Lindenblatt, Dennis; Dorrer, Holger; Cohrs, Susan; Zhernosekov, Konstantin; Köster, Ulli; Türler, Andreas; Fischer, Eliane; Schibli, Roger

    2014-10-01

    The L1 cell adhesion molecule (L1CAM) is considered a valuable target for therapeutic intervention in different types of cancer. Recent studies have shown that anti-L1CAM radioimmunotherapy (RIT) with (67)Cu- and (177)Lu-labelled internalising monoclonal antibody (mAb) chCE7 was effective in the treatment of human ovarian cancer xenografts. In this study, we directly compared the therapeutic efficacy of anti-L1CAM RIT against human ovarian cancer under equitoxic conditions with the radiolanthanide (177)Lu and the potential alternative (161)Tb in an ovarian cancer therapy model. Tb was produced by neutron bombardment of enriched (160)Gd targets. (161)Tb and (177)Lu were used for radiolabelling of DOTA-conjugated antibodies. The in vivo behaviour of the radioimmunoconjugates (RICs) was assessed in IGROV1 tumour-bearing nude mice using biodistribution experiments and SPECT/CT imaging. After ascertaining the maximal tolerated doses (MTD) the therapeutic impact of 50 % MTD of (177)Lu- and (161)Tb-DOTA-chCE7 was evaluated in groups of ten mice by monitoring the tumour size of subcutaneous IGROV1 tumours. The average number of DOTA ligands per antibody was 2.5 and maximum specific activities of 600 MBq/mg were achieved under identical radiolabelling conditions. RICs were stable in human plasma for at least 48 h. (177)Lu- and (161)Tb-DOTA-chCE7 showed high tumour uptake (37.8-39.0 %IA/g, 144 h p.i.) with low levels in off-target organs. SPECT/CT images confirmed the biodistribution data. (161)Tb-labelled chCE7 revealed a higher radiotoxicity in nude mice (MTD: 10 MBq) than the (177)Lu-labelled counterpart (MTD: 12 MBq). In a comparative therapy study with equitoxic doses, tumour growth inhibition was better by 82.6 % for the (161)Tb-DOTA-chCE7 than the (177)Lu-DOTA-chCE7 RIT. Our study is the first to show that anti-L1CAM (161)Tb RIT is more effective compared to (177)Lu RIT in ovarian cancer xenografts. These results suggest that (161)Tb is a promising candidate for future clinical applications in combination with internalising antibodies.

  11. Synthesis, Radiolabelling and In Vitro Characterization of the Gallium-68-, Yttrium-90- and Lutetium-177-Labelled PSMA Ligand, CHX-A''-DTPA-DUPA-Pep

    PubMed Central

    Baur, Benjamin; Solbach, Christoph; Andreolli, Elena; Winter, Gordon; Machulla, Hans-Jürgen; Reske, Sven N.

    2014-01-01

    Since prostate-specific membrane antigen (PSMA) has been identified as a diagnostic target for prostate cancer, many urea-based small PSMA-targeting molecules were developed. First, the clinical application of these Ga-68 labelled compounds in positron emission tomography (PET) showed their diagnostic potential. Besides, the therapy of prostate cancer is a demanding field, and the use of radiometals with PSMA bearing ligands is a valid approach. In this work, we describe the synthesis of a new PSMA ligand, CHX-A''-DTPA-DUPA-Pep, the subsequent labelling with Ga-68, Lu-177 and Y-90 and the first in vitro characterization. In cell investigations with PSMA-positive LNCaP C4-2 cells, KD values of ≤14.67 ± 1.95 nM were determined, indicating high biological activities towards PSMA. Radiosyntheses with Ga-68, Lu-177 and Y-90 were developed under mild reaction conditions (room temperature, moderate pH of 5.5 and 7.4, respectively) and resulted in nearly quantitative radiochemical yields within 5 min. PMID:24787458

  12. Crystal and electronic structure of the novel layered rare earth metal boride carbide Gd[sub 2]B[sub 3]C[sub 2

    SciTech Connect

    Wiitkar, F.; Halet, J.F.; Saillard, J.Y. ); Rogl, P. ); Bauer, J. )

    1994-03-30

    The crystal structure of Gd[sub 2]B[sub 3]C[sub 2] has been determined from single-crystal X-ray counter data. Gd[sub 2]B[sub 3]C[sub 2] crystallizes in a unique structure type with the orthorhombic space group Cmmm-D[sub 2h[sup 19

  13. LiB12PC, the first boron-rich metal boride with phosphorus--synthesis, crystal structure, hardness, spectroscopic investigations.

    PubMed

    Vojteer, Natascha; Sagawe, Vanessa; Stauffer, Julia; Schroeder, Melanie; Hillebrecht, Harald

    2011-03-07

    We present synthesis, crystal structure, hardness, and IR/Raman and UV/Vis spectra of a new compound with the mean composition LiB(12)PC. Transparent single crystals were synthesised from Ga, Li, B, red phosphorus and C at 1500 °C in boron nitride crucibles welded in Ta ampoules. Depending on the type of boron used for the synthesis we obtained colourless, brown and red single crystals with slightly different P/C ratios. Colourless LiB(12)PC crystallizes orthorhombic in the space group Imma (No. 74) with a=10.188(2) Å, b=5.7689(11) Å, c=8.127(2) Å and Z=4. Brown LiB(12)P(0.89)C(1.11) is very similar, but with a lower P content. Red single crystals of LiB(12)P(1.13)C(0.87) have a larger unit cell with a=10.4097(18) Å, b=5.9029(7) Å, c=8.2044(12) Å. EDX measurements confirm that the red crystals contain more phosphorus than the other ones. The crystal structure is characterized by a covalent network of B(12) icosahedra connected by exohedral B-B bonds and P-P, P-C or C-C units. Li atoms are located in interstitials. The structure is closely related to MgB(7), LiB(13)C(2) and ScB(13)C. LiB(12)PC fulfils the electron counting rules of Wade and also Longuet-Higgins. Measurements of Vickers micro-hardness (H(V)=27 GPa) revealed that LiB(12)PC is a hard material. The optical band gaps obtained from UV/Vis spectra match the colours of the crystals. Furthermore we report on the IR and Raman spectra.

  14. The Relationship of the Chemical Bonding Topology of High Critical Temperature Copper Oxide Superconductors to that of the Chevrel Phases and the Ternary Lanthanide Rhodium Borides.

    DTIC Science & Technology

    1987-12-11

    1964). 17j. Bardeen , in Superconductivity in d- and f-Band Metals, edited by D. Douglass (Plenum, New York, 1973), p. 1. • 1’ ’. : . -5- 18A.D.C...quality Research Triangle Park, NC 27709 Mr. John Boyle 1 e DTNSRDC Materials Branch Attn: Dr. H. Singerman Naval Ship Engineering Center Applied

  15. Synthesis of ferromagnetic nanoparticles, formic acid oxidation catalyst nanocomposites, and late-transition metal-boride intermetallics by unique synthetic methods and single-source precursors

    NASA Astrophysics Data System (ADS)

    Wellons, Matthew S.

    The design, synthesis, and characterization of magnetic alloy nanoparticles, supported formic acid oxidation catalysts, and superhard intermetallic composites are presented. Ferromagnetic equatomic alloy nanoparticles of FePt, FePd, and CoPt were synthesized utilizing single-source heteronuclear organometallic precursors supported on an inert water-soluble matrix. Direct conversion of the precursor-support composite to supported ferromagnetic nanoparticles occurs under elevated temperatures and reducing conditions with metal-ion reduction and minimal nanoparticle coalescence. Nanoparticles were easily extracted from the support by addition of water and characterized in structure and magnetic properties. Palladium and platinum based nanoparticles were synthesized with microwave-based and chemical metal-ion reduction strategies, respectively, and tested for catalytic performance in a direct formic acid fuel cell (DFAFC). A study of palladium carbide nanocomposites with various carbonaceous supports was conducted and demonstrated strong activity comparable to commercially available palladium black, but poor catalytic longevity. Platinum-lead alloy nanocomposites synthesized with chemical reduction and supported on Vulcan carbon demonstrated strong activity, excellent catalytic longevity, and were subsequently incorporated into a prototype DFAFC. A new method for the synthesis of superhard ceramics on polymer substrates called Confined Plasma Chemical Deposition (CPCD) was developed. The CPCD method utilizes a tuned Free Electron Laser to selectively decompose the single-source precursor, Re(CO)4(B3H8), in a plasma-like state resulting in the superhard intermetallic ReB2 deposited on polymer substrates. Extension of this method to the synthesis of other hard of superhard ceramics; WB4, RuB2, and B4C was demonstrated. These three areas of research show new synthetic methods and novel materials of technological importance, resulting in a substantial advance in their respective fields.

  16. CaNi/sub 12/B/sub 6/: a new boride of the SrNi/sub 12/B/sub 6/ structure type

    SciTech Connect

    Leshko, L.V.; Kuz'ma, Yu.B.

    1987-11-01

    The structure of CaNi/sub 12/B/sub 6/ has been examined from the diffraction pattern (DRON-3.0, Cu K/sub ..cap alpha../ radiation). When the pattern had been indexed to the hexagonal system, the cell parameters were found as ..cap alpha.. = 9.542 (3); c = 7.420 (3) A. The coordinates of the Ca and Ni atoms were refined via the PMNK program with an SM-4 computer, with the initial coordinates those for the metal atoms in SrNi/sub 12/B/sub 6/. The coordinates of the boron atoms were not refined, being taken the same as in SrNi/sub 12/B/sub 6/. The final values for the coordinates (space group R3m) are Ca at 3 (..cap alpha..) 000, B = 3.3 (5) A/sup 2/; 18 Nil at 18 (g) (x = 0.369(2)), B = 0.7(1) A/sup 2/; 18Ni2 at 18 (h) (x = 0.426(1), z = 0.031(2)), B = 0.5(1) A/sup 2/; 18B at 18 (h) (x = 0.191, z = 0.042), B = 3.3(5) A/sup 2/. The intensities were calculated for these coordinates, reliability factor R = 0.108

  17. Synthesis, processing and properties of TaC-TaB2-C Ceramics

    DTIC Science & Technology

    2010-01-01

    D. Borides 1. Introduction The group IV–VI transition metal borides , carbides, and nitrides with melting temperatures close to or above 3000 ◦C are...temperature and propagation velocity of the combustion front depended on the boride phase content. The synthesized products were porous with 15–30m...formation of borides and active carbon, accelerated diffusion processes in the bulk and along grain boundaries of the phases. U.S. Pat. No. 4,195,06623

  18. Molten Boron Phase-Change Thermal Energy Storage: Containment and Applicability to Microsatellites (Draft)

    DTIC Science & Technology

    2011-06-01

    differing vapor pressures of pure boron and the tantalum boride contaminants within the bulk material.38 Tantalum begins to form borides as...Work performed by Stroms et al. states that tungsten effusion cells will form a protective layer of tungsten boride . However, experimental...temperatures in this study did not reach the melting point of boron.40 Tungsten borides have been formed at temperatures as low as 1700 K.41 Again, this

  19. 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

  20. 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

  1. Computer Modeling of Basic Physico-Chemical Processes for DSEC Composites of System LaB6-MeB2(MeTi, Zr, Hf) at Macro-, Meso- and Microstructure Scales

    DTIC Science & Technology

    2010-07-15

    of their physical and chemical properties and appropriate service characteristics. The object of this investigation is eutectic boron- boride ...10 Fig 1.2. Scheme of production of samples of directed solidified boride - boride eutectics……………………………………………………. 12 Fig 1.3. Dependence of...worked out more than 20 monographs and 400 papers with key words «directed solidification, eutectics, boride - boride composites, computer modeling

  2. Radiosynovectomy of the elbow joint synovitis in rheumatoid arthritis treated with Lutetium - 177 labeled hydroxylapatite (Lu-177 HA) particulates; first case report and image of Lu -177 HA in the elbow joint.

    PubMed

    Kamaleshwaran, Koramadai Karuppusamy; Rajamani, Venkataraman; Thirumalaisamy, Subbiah Gounder; Chakraborty, Sudipta; Kalarikal, Radhakrishnan; Mohanan, Vyshakh; Shinto, Ajit Sugunan

    2014-10-01

    Rheumatoid arthritis is a chronic disease that is mainly characterized by asymmetric erosive synovitis, particularly affecting the peripheral joints. Radiation synovectomy or radiosynovectomy, also known as radiosynoviorthesis was first described in 1950's as a adjuvant treatment for rheumatoid arthritis. Radiosynovectomy is based on the irradiation of the joint synovium by the intra-articular administration of various β-emitting radiopharmaceuticals. Lu-177 has presence of gamma photons of imagable energy with low abundance which provides the additional benefit of carrying out simultaneous scintigraphy. We describe the first case report of use of Lu-177 hydroxylapatite particulates in a 35-year-old female patient who was presented with elbow joint synovitis due to rheumatoid arthritis.

  3. Microstructure and properties of borocarburized 15CrNi6 steel after laser surface modification

    NASA Astrophysics Data System (ADS)

    Kulka, M.; Pertek, A.

    2004-09-01

    The paper presents the results of laser heat treatment (LHT) of the borided layers produced on the carburized 15CrNi6 low-carbon steel. The two-step treatment carburizing followed by boriding is termed borocarburizing. Laser tracks were arranged by CO 2 laser beam as a single track and as multiple tracks formed in the shape of helical line. The microstructure in both cases consists of the following zones: iron borides (FeB and Fe 2B) of laser modified morphology, needle-like iron borides, carburized layer with heat affected zone (martensite and alloyed cementite), carburized layer without heat treatment and the substrate (ferrite and pearlite). X-ray microanalysis of the laser modified borocarburized specimen confirmed the presence of the same two types of iron borides (FeB and Fe 2B), like those indicated in the as-borided layer. The layer after borocarburizing and LHT has a high microhardness of iron borides, reducing the hardness gradient between the diffusion layer and the substrate in comparison with only borided layer. Probably, the brittleness of this layer is lower. The improved wear resistance of this layer has been found in comparison with borided and borocarburized layers after conventional heat treatment. It is probably result of globular iron boride presence after laser surface modification.

  4. Chemistry and bifunctional chelating agents for binding (177)Lu.

    PubMed

    Parus, Józef L; Pawlak, Dariusz; Mikolajczak, Renata; Duatti, Adriano

    2015-01-01

    A short overview of fundamental chemistry of lutetium and of structural characteristics of lutetium coordination complexes, as relevant for understanding the properties of lutetium-177 radiopharmaceuticals, is presented. This includes basic concepts on lutetium electronic structure, lanthanide contraction, coordination geometries, behavior in aqueous solution and thermodynamic stability. An illustration of the structure and binding properties of the most important chelating agents for the Lu(3+) ion in aqueous solution is also reported with specific focus on coordination complexes formed with linear and macrocyclic polydentate amino-carboxylate donor ligands.

  5. Quantitative Electron-Excited X-Ray Microanalysis of Borides, Carbides, Nitrides, Oxides, and Fluorides with Scanning Electron Microscopy/Silicon Drift Detector Energy-Dispersive Spectrometry (SEM/SDD-EDS) and NIST DTSA-II.

    PubMed

    Newbury, Dale E; Ritchie, Nicholas W M

    2015-10-01

    A scanning electron microscope with a silicon drift detector energy-dispersive X-ray spectrometer (SEM/SDD-EDS) was used to analyze materials containing the low atomic number elements B, C, N, O, and F achieving a high degree of accuracy. Nearly all results fell well within an uncertainty envelope of ±5% relative (where relative uncertainty (%)=[(measured-ideal)/ideal]×100%). Quantification was performed with the standards-based "k-ratio" method with matrix corrections calculated based on the Pouchou and Pichoir expression for the ionization depth distribution function, as implemented in the NIST DTSA-II EDS software platform. The analytical strategy that was followed involved collection of high count (>2.5 million counts from 100 eV to the incident beam energy) spectra measured with a conservative input count rate that restricted the deadtime to ~10% to minimize coincidence effects. Standards employed included pure elements and simple compounds. A 10 keV beam was employed to excite the K- and L-shell X-rays of intermediate and high atomic number elements with excitation energies above 3 keV, e.g., the Fe K-family, while a 5 keV beam was used for analyses of elements with excitation energies below 3 keV, e.g., the Mo L-family.

  6. 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

  7. 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

  8. 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

  9. On the Nucleation and Growth of Alpha-Ti Off of TiB Precipitates (PREPRINT)

    DTIC Science & Technology

    2010-01-01

    that a dispersion of thermally stable titanium- boride particles, formed by trace boron additions, was effective in restricting the grain growth...reinforced by the TiB phase [6-13]. The boride particles act as the pinning sites for the grain boundaries. In the TiB reinforced Ti-6Al-4V alloy...these titanium- boride particles provide additional nucleation sites for the -Ti precipitates in addition to the -Ti precipitates that form along

  10. Gadolinium: Central Metal of the Lanthanoids

    ERIC Educational Resources Information Center

    Laing, Michael

    2009-01-01

    The physical and chemical properties of gadolinium are compared with those of the other lanthanoids. Some properties are intermediate between those of lanthanum and lutetium; some between those of barium and hafnium; and others (unexpectedly) between those of ytterbium and lutetium. Both the remarkably high molar heat capacity of the metal and the…

  11. Gadolinium: Central Metal of the Lanthanoids

    ERIC Educational Resources Information Center

    Laing, Michael

    2009-01-01

    The physical and chemical properties of gadolinium are compared with those of the other lanthanoids. Some properties are intermediate between those of lanthanum and lutetium; some between those of barium and hafnium; and others (unexpectedly) between those of ytterbium and lutetium. Both the remarkably high molar heat capacity of the metal and the…

  12. Design Study of Triggered Isomer Heat Exchanger-Combustion Hybrid Jet Engine for High Altitude Flight

    DTIC Science & Technology

    2007-11-02

    Lift (lbf) l Nozzle length (ft) lbf Pounds force lbm Pounds mass LPC π Low pressure compressor pressure ratio Lu Lutetium M Mach number m0 Mass...sponsoring an international group of physicists to research an exciting new process for extracting energy from isomers of Lutetium (Lu), Hafnium (Hf), and

  13. Optical Properties of Nd Doped Rare Earth Vanadates (Preprint)

    DTIC Science & Technology

    2010-07-01

    common of these is yttrium orthovanadate, other rare earth vanadates such as lutetium vanadate and gadolinium vanadate are being used for their...state laser hosts such as YAG. While the most common of these is yttrium orthovanadate, other rare earth vanadates such as lutetium vanadate and

  14. The United States’ Vulnerability to Coercion by China in the Rare Earths Market

    DTIC Science & Technology

    2012-12-14

    Promethium , Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium, Thulium, Yterbium, and Lutetium. Rare earth minerals are utilized in...Scandium, Yttrium, Lanthanum, Cerium, Praseodymium, Neodymium, Promethium , Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium...Neodymium, Promethium , Holmium, Europium, Gadolinium, Praseodymium, Dysprosium, Lutetium, Samarium, Erbium, Thulium, and Yterbium belong to a group

  15. Effect of Annealing on the Passive Film Stability and Corrosion Resistance of New Families of Iron-Based Amorphous Metals

    DTIC Science & Technology

    2011-06-01

    in the expected carbides or borides . Although these phases are potentially present, they do not exist in any large quantity. SAM4X7 has similar...score for titanium mixed with iron and chromium. Once again, titanium carbide and titanium boride did not appear in any large quantity. Because

  16. 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

  17. 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

  18. 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.

  19. Microstructure and properties of borocarburized and laser-modified 17CrNi6-6 steel

    NASA Astrophysics Data System (ADS)

    Kulka, M.; Makuch, N.; Pertek, A.; Piasecki, A.

    2012-06-01

    Two-step process: carburizing followed by boriding was applied to the formation of borocarburized layers. The boride layer formed on the substrate of changeable chemical and phase composition (e.g. borocarburized layer) was called "gradient boride layer", in contrast to "typical boride layer", formed on the substrate of constant chemical and phase composition. Until now, the typical heat treatment of borocarburized layer consisted of treatment through hardening: quenching in oil and low-temperature tempering. In this paper, instead of treatment through hardening, laser-heat treatment was employed. The properties of such layer were compared to the properties of typical carburized layer. Three zones characterized the microstructure of laser-modified borocarburized layer: iron borides (FeB+Fe 2B) of modified morphology, hardened carburized zone (heat affected zone) and carburized layer without heat treatment. X-ray microanalysis indicated the increased boron concentration close to the surface due to the occurrence of a mixture of FeB and Fe 2B borides. Near to the hardened carburized zone, Fe 2B phase occurred in the laser-modified boride zone. Laser-heat treated borocarburized layer was characterized by higher microhardness at the surface than that obtained in case of carburized layer. It was caused by the iron borides (FeB+Fe 2B) occurrence at the surface, as a consequence of boriding process. However, the carburized layer was characterized by considerably larger hardened zone. Higher abrasive wear resistance, but lower low-cycle fatigue strength in comparison with the carburized layer, characterized the gradient boride layer formed by borocarburizing and laser surface modification. The indentation craters obtained on the surface of laser-heat treated borocarburized layer revealed sufficient cohesion (HF3 standard). The use of laser-modified borocarburized layers may be advantageous under conditions of high abrasive wear of mating parts. In case of parts, which

  20. Thermal expansion and lattice dynamics of RB66 compounds at low temperatures

    SciTech Connect

    Novikov, V V; Avdashchenko, D V; Mitroshenkov, N V; Matovnikov, A V; Budko, Serguei L

    2014-10-01

    Thermal characteristics of the phonon and magnon subsystems of icosahedral borides RB66 (R = Gd, Tb, Dy, Ho, Eu, or Lu) have been studied based on the obtained experimental data on the thermal expansion of the borides and the earlier results on their heat capacity in the range of 2–300 K. The contribution to the expansion of borides containing paramagnetic R 3+ ions, which is characteristic of transition to the spin-glass state, has been revealed. The phonon spectrum moments of RB66 compounds and the Grüneisen parameters have been calculated.

  1. Comment on 'A planar refractive x-ray lens made of nanocrystalline diamond'[J. Appl. Phys. 108, 123107 (2010)

    SciTech Connect

    Kroon, R. E.

    2013-05-28

    The material LuAG (lutetium aluminium garnet) has been confused with LAG (lanthanum aluminium garnet). In general, aluminium garnet phases only occur for the smaller trivalent metal cations and LAG is not known to have been synthesized.

  2. 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.

  3. RESEARCH STUDIES ON THERMIONIC CONVERTERS, EMITTER SHELL PHASE.

    DTIC Science & Technology

    BERYLLIUM COMPOUNDS, CARBIDES, SILICON COMPOUNDS, ENERGY CONVERSION, PERMEABILITY, GASES, TEST EQUIPMENT, CONTAINERS, PYROLYTIC GRAPHITE, THORIUM...COMPOUNDS, ZIRCONIUM COMPOUNDS, NITRIDES, BORON COMPOUNDS, BORIDES, TITANIUM COMPOUNDS, SILICIDES , TUNGSTEN COMPOUNDS, TANTALUM COMPOUNDS, PHYSICAL PROPERTIES, MECHANICAL PROPERTIES.

  4. 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.

  5. 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

  6. 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

  7. 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

  8. AlM2B2 (M  =  Cr, Mn, Fe, Co, Ni): a group of nanolaminated materials

    NASA Astrophysics Data System (ADS)

    Kádas, K.; Iuşan, D.; Hellsvik, J.; Cedervall, J.; Berastegui, P.; Sahlberg, M.; Jansson, U.; Eriksson, O.

    2017-04-01

    Combining theory with experiments, we study the phase stability, elastic properties, electronic structure and hardness of layered ternary borides AlCr2B2, AlMn2B2, AlFe2B2, AlCo2B2, and AlNi2B2. We find that the first three borides of this series are stable phases, while AlCo2B2 and AlNi2B2 are metastable. We show that the elasticity increases in the boride series, and predict that AlCr2B2, AlMn2B2, and AlFe2B2 are more brittle, while AlCo2B2 and AlNi2B2 are more ductile. We propose that the elasticity of AlFe2B2 can be improved by alloying it with cobalt or nickel, or a combination of them. We present evidence that these ternary borides represent nanolaminated systems. Based on SEM measurements, we demonstrate that they exhibit the delamination phenomena, which leads to a reduced hardness compared to transition metal mono- and diborides. We discuss the background of delamination by analyzing chemical bonding and theoretical work of separation in these borides.

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

    PubMed

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

    2017-04-10

    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.

  10. 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.

  11. 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

  12. 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.

  13. A Study of Chromo-Boronizing on DIN 1.2714 Steel by Duplex Surface Treatment

    NASA Astrophysics Data System (ADS)

    Aghaie-Khafri, M.; Mohamadpour Nazar Abady, M.

    2012-06-01

    In the current study, the microhardness, layer depth, corrosion properties, and kinetics of chromium boride coatings on DIN 1.2714 hot-worked tool steel have been investigated. Thermodiffusion chromium boride coatings have been carried out for the first time by a duplex salt bath immersion coating by chromizing at 1050°C followed by boronizing at 950°C, 1000°C, and 1050°C (chromo-boronizing). The coating layer obtained was hard (2482 HV), compact, and homogeneous. The kinetics of the chromium boride coating followed a parabolic relation ( d 2 = Kt) and the activation energy of the formation of the chromo-boronized layer was calculated as 132 kJ/mol. The corrosion resistance of the coating was evaluated by potentiodynamic polarization in 3.5% NaCl solution. The results showed the degradation of the corrosion properties of the coated samples.

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

    SciTech Connect

    Dwivedi, Shalini; Sharma, Yamini; 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. It 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.

  15. Synthesis and Characterization of TiB2 Reinforced Aluminium Matrix Composites: A Review

    NASA Astrophysics Data System (ADS)

    Kumar, Narendra; Gautam, Gaurav; Gautam, Rakesh Kumar; Mohan, Anita; Mohan, Sunil

    2016-10-01

    Aluminium-matrix composites (AMCs) are developed to meet the demands of light weight high performance materials in aerospace, automotive, marine and other applications. The properties of AMCs can be tailored suitably by combinations of matrix, reinforcement and processing route. AMCs are one of the most attractive alternatives for the manufacturing of light weight and high strength parts due to their low density and high specific strength. There are various techniques for preparing the AMCs with different reinforcement particles. In AMCs, the reinforcements are usually in the form of metal oxides, carbides, borides, nitrides and their combination. Among the various reinforcements titanium di-boride (TiB2) is of much interest due to its excellent stiffness, hardness, and wear resistance. This paper attempts to provide an overview to explore the possibilities of synthesizing titanium di-boride reinforced AMCs with different techniques. The mechanical and tribological properties of these composites have been emphasized to project these as tribo-materials.

  16. M3B2 and M5B3 Formation in Diffusion-Affected Zone During Transient Liquid Phase Bonding Single-Crystal Superalloys

    NASA Astrophysics Data System (ADS)

    Sheng, Naicheng; Hu, Xiaobing; Liu, Jide; Jin, Tao; Sun, Xiaofeng; Hu, Zhuangqi

    2015-04-01

    Precipitates in the diffusion-affected zone (DAZ) during transient liquid phase bonding (TLP) single-crystal superalloys were observed and investigated. Small size and dendritic-shaped precipitates were identified to be M3B2 borides and intergrowth of M3B2/M5B3 borides. The orientation relationships among M3B2, M5B3, and matrix were determined using transmission electron microscope (TEM). Composition characteristics of these borides were also analyzed by TEM energy-dispersive spectrometer. Because this precipitating phenomenon deviates from the traditional parabolic transient liquid phase bonding model which assumed a precipitates free DAZ during TLP bonding, some correlations between the deviation of the isothermal solidification kinetics and these newly observed precipitating behaviors were discussed and rationalized when bonding the interlayer containing the high diffusivity melting point depressant elements and substrates of low solubility.

  17. 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.

  18. 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.

  19. 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.

  20. Method of boronizing transition-metal surfaces

    SciTech Connect

    Koyama, K.; Shimotake, H.

    1981-08-28

    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/sup 0/C and a surface boride layer of that transition metal is formed within a period of about 24 hours on the substrate surface.

  1. Thermodynamical and thermoelectric properties of boron doped YPd3 and YRh3

    NASA Astrophysics Data System (ADS)

    Dwivedi, Shalini; Sharma, Ramesh; Sharma, Yamini

    2016-05-01

    The structural, electronic, thermal, and optical properties of borides of cubic non-magnetic YX3 (X=Rh, Pd) compounds and their borides which crystallize in the AuCu3 structure have been studied using the density functional theory (DFT). The flat bands in the vicinity of EF which are associated with superconductivity appear in YPd3 and YRh3 band structures. However, the B s-states enhance the flat band only in YRh3B. The optical properties clearly show that boron insertion modifies the absorption and transmittance. The YX3 alloys and their borides exhibit valuable changes in the thermopower and ZT. It 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.

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

    SciTech Connect

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

    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 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.

  3. New Process for Grain Refinement of Aluminum. Final Report

    SciTech Connect

    Dr. Joseph A. Megy

    2000-09-22

    A new method of grain refining aluminum involving in-situ formation of boride nuclei in molten aluminum just prior to casting has been developed in the subject DOE program over the last thirty months by a team consisting of JDC, Inc., Alcoa Technical Center, GRAS, Inc., Touchstone Labs, and GKS Engineering Services. The Manufacturing process to make boron trichloride for grain refining is much simpler than preparing conventional grain refiners, with attendant environmental, capital, and energy savings. The manufacture of boride grain refining nuclei using the fy-Gem process avoids clusters, salt and oxide inclusions that cause quality problems in aluminum today.

  4. Superhard W0.5Ta0.5B nanowires prepared at ambient pressure

    NASA Astrophysics Data System (ADS)

    Yeung, Michael T.; Akopov, Georgiy; Lin, Cheng-Wei; King, Daniel J.; Li, Rebecca L.; Sobell, Zachary C.; Mohammadi, Reza; Kaner, Richard B.

    2016-11-01

    The primary focus of superhard materials development has relied on chemical tuning of the crystal structure. While these intrinsic effects are invaluable, there is a strong possibility that hardness can be dramatically enhanced using extrinsic effects. Here, we demonstrate that the superhard metal W0.5Ta0.5B can be prepared as nanowires through flux growth. The aspect ratios of the nanowires are controlled by the concentration of boride in molten aluminum, and the nanowires grow along the boron-boron chains, confirmed via electron diffraction. This morphology inherently results from the crystal habit of borides and can inspire the development of other nanostructured materials.

  5. 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.

  6. 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.

  7. 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.

  8. Influence of a corrosive-abrasive medium on the wear resistance of 12Kh18N10T steel with surface hardening

    SciTech Connect

    Golubets, V.M.; Kozub, V.V.; Shchuiko, Ya.V.; Pashechko, M.I.

    1987-11-01

    The authors study the wear and corrosion resistance of 12Kh18N10T steel after diffusion boriding, electrospark alloying, and combined hardening in a corrosive abrasive medium consisting of 50 percent sand and 3 percent NaCl with hydrochloric acid added to obtain a pH of 1. Metallographic analysis revealed a 40-micrometer-deep case with a microhardness of 6-8.5 GPa on the surface. X-ray diffraction established that the boride case consists of an FeB phase alloyed with chromium and nickel. Results are graphed.

  9. Properties of particle phases for metal-matrix-composite design.

    PubMed

    Baron, C; Springer, H

    2017-06-01

    Successful metallurgical design of metal-matrix-composites relies on the knowledge of the intrinsic property profiles of the metal matrix and especially the compounds employed for particles, whiskers or fibres. In this work we compiled the key properties melting point, bulk modulus, shear modulus, Young׳s modulus, density, hardness, Poisson׳s ratio and structure/space group from the widespread literature data for the most relevant compound types, i.e. borides, carbo-borides, carbides, oxides, nitrides and intermetallic phases.

  10. X-ray diffraction study of W-B elemental powder mixtures after high-energy ball-milling.

    NASA Astrophysics Data System (ADS)

    Stubičar, Mirko; Tonejc, Antun; Stubičar, Nada

    Very high temperatures are needed to prepare W-B compounds. However, the results obtained in this study demonstrate a possibility of inducing the formation of W2B, WB or WB4 tungsten borides, in air and at room temperature, using the high-energy ball-mill treatment on appropriate compositions of the W-B elemental powder mixtures. The present results throw a new light on the synthesis of tungsten borides, and on the accuracy of the equilibrium W-B phase diagram.

  11. 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.

  12. Protective metal matrix coating with nanocomponents

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    Experience of nanocrystalline chromium, titanium, silicon carbides and borides components application as nickel, zinc, chromium based electrodeposited composite coating is generalized. Electrodepositing conditions are determined. Structure and physicochemical properties of coatings, namely micro-hardness, adhesion to steel base, inherent stresses, heat resistance, corrosion currents, en-during quality, and their change during isothermal annealing are studied. As is shown, nanocomponents act as metal matrix modifier. Technological and economic feasibility study to evaluate expediency of replacing high priced nano-diamonds with nanocrystalline borides and carbides is undertaken.

  13. Computational Design of ZrO2-SiO2 Coatings for Oxidation of ZrB2/ZrC Composites Containing ZrSix Intermetallics at 1700 degrees C

    DTIC Science & Technology

    2009-03-01

    method. The model of the Zr boride /carbide composite with a Si02/Zr02/ZrSix scale simulates the development of the strain/stress distribution under a... modeling the scale/matrix region is shown in Figure 2. The ZrSix precipitates simulate the silicide along the scale/matrix interface as a first step. For...with the scale/matrix interface. Bronson-Chessa (University of Texas at El Paso) for the simulations with larger areas of boride and carbide

  14. Scattering Effects in Proximity Effect Tunneling Spectroscopy.

    NASA Astrophysics Data System (ADS)

    Gai, Wei

    PETS (Proximity Effect Tunneling Spectroscopy) technique has been applied to Niobium/Yttrium and Niobium/Lutetium bilayers. We have determined electron - phonon interaction parameter lambda_{rm e -ph} is 0.55 for Yttrium and 0.67 for Lutetium. Spin fluctuations parameter lambda_{ rm S} is 0.20 for Yttrium and 0.33 for Lutetium. We found that the large spin fluctuations in Yttrium and Lutetium has responsibility to the absence of superconductivity in them. Our results have given a reasonable explanation of high superconducting transition temperature in them under high pressure. The large reflection coefficient and strong diffuse scattering at Nb/Y and Nb/Lu interface has been discovered and it should have strong influence on the transport properties of metallic superlattices. From the modeling study of elastic scattering in proximity effect tunnel junctions, we have explained why some conventional made high {rm T_{C}} superconducting tunnel junctions give ideal like characteristics in the gap region but variable strength phonon structures in the phonon region.

  15. Dihydrogen addition in a dinuclear rare-earth metal hydride complex supported by a metalated TREN ligand.

    PubMed

    Venugopal, Ajay; Fegler, Waldemar; Spaniol, Thomas P; Maron, Laurent; Okuda, Jun

    2011-11-09

    The dinuclear lutetium dihydride dication supported by metalated tripodal ligands undergoes facile hydrogenolysis with H(2) to form a trihydride dication. Molecular orbital analysis shows that the LUMO is a bonding Lu···Lu orbital that is poised to activate dihydrogen.

  16. Reestablishing Strategic and Critical Material Security in the Department of Defense

    DTIC Science & Technology

    2011-05-11

    66 Dysprosium 58 Cerium 67 Holmium 59 Praseodymium 68 Erbium 60 Neodymium 69 Thulium 61 Promethium 70 Ytterbium 62 Samarium 71 Lutetium 63 Europium...LEADERSHIP New Mission Examples • Acquire ferro- dysprosium as a vendor-managed rolling inventory. – Metal alloy used to manufacture the popular

  17. The Refined Three-Dimensional Structure of Pectate Lyase C from Erwinia chrysanthemi at 2.2 Angstrom Resolution (Implications for an Enzymatic Mechanism).

    PubMed Central

    Yoder, M. D.; Jurnak, F.

    1995-01-01

    The crystal structure of pectate lyase C (EC 4.2.2.2) from the enterobacterium Erwinia chrysanthemi (PelC) has been refined by molecular dynamics techniques to a resolution of 2.2 A to an R factor of 17.97%. The final model consists of 352 of the total 353 amino acids and 114 solvent molecules. The root-mean-square deviation from ideality is 0.009 A for bond lengths and 1.768[deg] for bond angles. The structure of PelC bound to the lanthanide ion lutetium, used as a calcium analog, has also been refined. Lutetium inhibits the enzymatic activity of the protein, and in the PelC-lutetium structure, the ion binds in the putative calcium-binding site. Five side-chain atoms form ligands to the lutetium ion. An analysis of the atomic-level model of the two protein structures reveals possible implications for the enzymatic mechanism of the enzyme. PMID:12228363

  18. Yttrium and rare earth stabilized fast reactor metal fuel

    SciTech Connect

    Guon, J.; Grantham, L.F.; Specht, E.R.

    1992-05-12

    This patent describes an improved metal alloy reactor fuel consisting essentially of uranium, plutonium, and at least one element from the group consisting of yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium.

  19. Rare-Earth Metals and Their Applications in Aviation

    DTIC Science & Technology

    1984-08-01

    promethium , samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium and yttrium. Based on the...yttrium. Aside from these, promethium is an artifical element, it has radioactivity and is almost non-existent in the earth’s crust. The term "rate-earth

  20. Nuclear data sheets for A = 157

    SciTech Connect

    Helmer, R. G.

    1996-06-01

    The experimental results from the various reaction and decay studies leading to nuclides in the A=157 mass chain have been reviewed. These data are summarized and presented, together with adopted level schemes and properties. Data is presented for isotopes of dysprosium, erbium, europium, gadolinium, hafnium, holmium, lutetium, promethium, samarium, tantalum, terbium, thulium, ytterbium, and neodymium. 301 refs.

  1. Methods of increasing the erosion resistance of powder metallurgy steel

    SciTech Connect

    Kulu, P.A.

    1987-09-01

    The authors comparatively assess the effects of a variety of surface hardening methods--including carburizing, boriding, chromizing, and carbochromizing, as well as the flame, plasma arc, and detonation spraying of nickel and molybdenum coatings--on the wear, corrosion resistance, and pore structure of steel 45, and outline testing procedures used to arrive at their results.

  2. 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.

  3. 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.

  4. Characterization of natural zeolite clinoptilolite for sorption of contaminants

    NASA Astrophysics Data System (ADS)

    Xingu-Contreras, E.; García-Rosales, G.; García-Sosa, I.; Cabral-Prieto, A.; Solache-Ríos, M.

    2015-06-01

    The nanoparticles technology has received considerable attention for its potential applications in groundwater treatment for the removal of various pollutants as Cadmium. In this work, iron boride nanoparticles were synthesized in pure form and in presence of homo-ionized zeolite clinoptilolite, as support material. These materials were used for removing Cd (II) from aqueous solutions containing 10, 50, 100, 150, 200, 250, 300 and 400 mg/L. The characterization of these materials was made by using X-ray Diffraction, Scanning Electron Microscopy and Mössbauer Spectroscopy. Pure iron boride particles show a broad X-ray diffraction peak centered at 45∘ (2 𝜃), inferring the presence of nanocrystals of Fe2B as identified from Mössbauer Spectroscopy. The size of these Fe2B particles was within the range of 50 and 120 nm. The maximum sorption capacities for Cd (II) of iron boride particles and supported iron boride particles in homo-ionized zeolitic material were nearly 100 %. For homo-ionized zeolite and homo-ionized zeolite plus sodium borohydride was ≥ 95 %.

  5. Boron Carbides As Thermo-electric Materials

    NASA Technical Reports Server (NTRS)

    Wood, Charles

    1988-01-01

    Report reviews recent theoretical and experimental research on thermoelectric materials. Recent work with narrow-band semiconductors demonstrated possibility of relatively high thermoelectric energy-conversion efficiencies in materials withstanding high temperatures needed to attain such efficiencies. Among promising semiconductors are boron-rich borides, especially boron carbides.

  6. Determination of the conditions of boronizing steel with heating by laser radiation

    SciTech Connect

    Lyakhovich, L.S.; Isakov, S.A.; Kartoshkin, V.M.; Pakhadnya, V.P.

    1986-05-01

    The purpose of the authors' investigations is to determine the conditions of obtaining boride coatings on steels heated by laser radiation. The investigations were carried out on an experimental installation containing a continuous-wave CO/sub 2/ laser with a power of up to 800 W (wavelength 10.6 mu m), a device for gripping and shifting the specimens with specified speed, focusing lens of KC1 with focal length 223 mm. It was determined that a boride layer of high quality, 80-120 mu m thick, is attained with a power density of the laser radiation on the surface of steel 45 equal to 0.4 GW/m/sup 2/ and a speed of shifting the specimen of 6-8 mm/sec. Basically, the boride layer consists of the phases Fe/sub 2/B and FeB. The structure and phase composition of the boride layer are predominantly affected by the thickness of the layer of amorphous boron applied to the surface of the specimen.

  7. 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.

  8. Laser alloying of bearing steel with boron and self-lubricating addition

    NASA Astrophysics Data System (ADS)

    Kotkowiak, Mateusz; Piasecki, Adam; Kulka, Michał

    2016-12-01

    100CrMnSi6-4 bearing steel has been widely used for many applications, e.g. rolling bearings which work in difficult operating conditions. Therefore, this steel has to be characterized by special properties such as high wear resistance and high hardness. In this study laser-boriding was applied to improve these properties. Laser alloying was conducted as the two step process with two different types of alloying material: amorphous boron only and amorphous boron with addition of calcium fluoride CaF2. At first, the surface was coated with paste including alloying material. Second step of the process consisted in laser re-melting. The surface of sample, coated with the paste, was irradiated by the laser beam. In this study, TRUMPF TLF 2600 Turbo CO2 laser was used. The microstructure, microhardness and wear resistance of both laser-borided layer and laser-borided layer with the addition of calcium fluoride were investigated. The layer, alloyed with boron and CaF2, was characterized by higher wear resistance than the layer after laser boriding only.

  9. Laser Boronizing of Stainless Steel with Direct Diode Laser

    NASA Astrophysics Data System (ADS)

    Kusuhara, Takayoshi; Morimoto, Junji; Abe, Nobuyuki; Tsukamoto, Masahiro

    Boronizing is a thermo-chemical surface treatment in which boron atoms are diffused into the surface of a work piece to form borides with the base material. When applied to the metallic materials, boronizing provides wear and abrasion resistance comparable to sintered carbides. However conventional boronizing is carried out at temperatures ranging from 800°C to 1050°C and takes from one to several hours. The structure and properties of the base material is influenced considerably by the high temperature and long treatment time. In order to avoid these drawbacks of conventional boronizing, laser-assisted boronizing is investigated which activates the conventional boronizing material and the work piece with a high density laser power. In this study, effect of laser characteristics was examined on the laser boronizing of stainless steel. After laser boronizing, the microstructure of the boride layer was analyzed with an optical microscope, electron probe micro analyser(EPMA) and X-ray diffractometer (XRD). The mechanical properties of borided layer were evaluated using Vickers hardness tester and sand erosion tester. Results showed that the boride layer was composed of NiB, CrB, FeB and Fe2B, and get wear resistance.

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

    SciTech Connect

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

    1985-02-01

    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.

  11. 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.

  12. 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.

  13. Ultra-High Temperature Ceramics for solar receivers: spectral and high-temperature emittance characterization

    NASA Astrophysics Data System (ADS)

    Sani, E.; Mercatelli, L.; Jafrancesco, D.; Sans, J. L.; Sciti, D.

    2012-12-01

    We report on the preparation, room temperature spectral reflectance and high-temperature thermal emittance characterization of different boride and carbide Ultra-High Temperature Ceramics (UHTCs). The investigated samples are compared with a reference material for solar absorber applications, i.e. silicon carbide. We show that spectral and thermal emittance properties of UHTCs are promising for novel solar receivers.

  14. Effect of refining treatment on the diffusion saturation of refractory metals with boron and silicon

    SciTech Connect

    Dzyadykevich, Y.V.

    1995-06-01

    Earlier studies showed that annealing of refractory metals in a getter mixture ensures removal of interstitial impurities from the interior of the metal, thus enhancing its plasticity. Therefore, it is interesting to study the effect of this refining treatment on the formation of boride and silicide coatings on refractory metals (niobium, tantalum, molybdenum, and tungsten).

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

    SciTech Connect

    Xing Zhang, Jiu; Hong Bao, Li; Lin Zhou, Shen E-mail: Baolihong_10@yahoo.com.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)

  16. 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

  17. 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

    2017-01-01

    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.

  18. 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.

  19. Applications Overview of IHDIV NSWC’s Reactive Materials

    DTIC Science & Technology

    2009-04-01

    metal oxide reactions Thermite and MIC reactions – Intermetallic reactions Aluminides Borides Carbides – Metal/fluorine systems Ultra-fine powders...Assessment (MUA) of RM payload for USECENTCOM Effective Kill Environment • Sustained target temperature >500F • Biocides created • Cl2 , and Titanium

  20. Laser surface alloying of commercially pure titanium with boron and carbon

    NASA Astrophysics Data System (ADS)

    Makuch, N.; Kulka, M.; Dziarski, P.; Przestacki, D.

    2014-06-01

    Laser surface alloying with boron and carbon was applied to produce the composite layers, reinforced by the hard ceramic phases (titanium borides and titanium carbides), on commercially pure titanium. The external cylindrical surface of substrate material was coated by paste containing boron, boron and graphite, or graphite. Then, the laser re-melting was carried out with using the continuous-wave CO2 laser. This enabled the formation of laser-borided, laser-borocarburized, and laser-carburized layers. The microstructure or the re-melted zone consisted of the hard ceramic phases (TiB+TiB2, TiB+TiB2+TiC, or TiC) located in the eutectic mixture of Tiα'-phase with borides, borides and carbides, or carbides, respectively. All the composite layers were characterized by the sufficient cohesion. The significant increase in microhardness and in wear resistance of all the laser-alloyed layers was observed in comparison with commercially pure titanium. The percentage of hard ceramic phases in more plastic eutectic mixture influenced the measured microhardness values. The dominant wear mechanism (abrasive or adhesive) depended on the method of laser alloying, and the type of test used. The wear tests for longer duration, without the change in the counter specimen, created the favourable conditions for adhesive wear, while during the shorter tests the abrasive wear dominated, as a rule.

  1. Anomalies in thermal expansion and heat capacity of TmB50 at low temperatures: magnetic phase transition and crystal electric field effect.

    PubMed

    Novikov, V V; Zhemoedov, N A; Mitroshenkov, N V; Matovnikov, A V

    2016-11-01

    We experimentally study the heat capacity and thermal expansion of thulium boride (TmB50) at temperatures of 2-300 K. The wide temperature range (2-180 K) of boride negative expansion was revealed. We found the anomalies in C(T) heat capacity temperature dependence, attributed to the Schottky contribution (i.e. the influence of the crystal electric field: CEF), as well as the magnetic phase transition. CEF-splitting of the f-levels of the Tm(3+) ion was described by the Schottky function of heat capacity with a quasi-quartet in the ground state. Excited multiplets are separated from the ground state by energy gaps δ1 = 100 K, and δ2 ≈ 350 K. The heat capacity maximum at Tmax ≈ 2.4 K may be attributed to the possible magnetic transition in TmB50. Other possible causes of the low-temperature maximum of C(T) dependence are the nonspherical surroundings of rare earth atoms due to the boron atoms in the crystal lattice of the boride and the emergence of two-level systems, as well as the splitting of the ground multiplet due to local magnetic fields of the neighboring ions of thulium. Anomalies in heat capacity are mapped with the thermal expansion features of boride. It is found that the TmB50 thermal expansion characteristic features are due to the influence of the CEF, as well as the asymmetry of the spatial arrangement of boron atoms around the rare earth atoms in the crystal lattice of RB50. The Grüneisen parameters, corresponding to the excitation of different multiplets of CEF-splitting, were determined. A satisfactory accordance between the experimental and estimated temperature dependencies of the boride thermal expansion coefficient was achieved.

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

    SciTech Connect

    Wu, Ming-Wei 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, and 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.

  3. Raman spectra of high- κ dielectric layers investigated with micro-Raman spectroscopy comparison with silicon dioxide.

    PubMed

    Borowicz, P; Taube, A; Rzodkiewicz, W; Latek, M; Gierałtowska, S

    2013-01-01

    Three samples with dielectric layers from high- κ dielectrics, hafnium oxide, gadolinium-silicon oxide, and lanthanum-lutetium oxide on silicon substrate were studied by Raman spectroscopy. The results obtained for high- κ dielectrics were compared with spectra recorded for silicon dioxide. Raman spectra suggest the similarity of gadolinium-silicon oxide and lanthanum-lutetium oxide to the bulk nondensified silicon dioxide. The temperature treatment of hafnium oxide shows the evolution of the structure of this material. Raman spectra recorded for as-deposited hafnium oxide are similar to the results obtained for silicon dioxide layer. After thermal treatment especially at higher temperatures (600°C and above), the structure of hafnium oxide becomes similar to the bulk non-densified silicon dioxide.

  4. Radiation damage of LSO crystals under γ- and 24 GeV protons irradiation

    NASA Astrophysics Data System (ADS)

    Auffray, E.; Barysevich, A.; Fedorov, A.; Korjik, M.; Koschan, M.; Lucchini, M.; Mechinski, V.; Melcher, C. L.; Voitovich, A.

    2013-09-01

    Irradiation damage of undoped and low Ce doped lutetium oxyorthosilicate has been investigated. Crystals were irradiated with both a 60Co γ-quanta source with an absorbed dose of 2000 Gy and, at CERN PS, a high-rate 24 GeV proton beam with a fluence of ˜3.6×1013 p/cm2. Both irradiations produced a similar set of induced absorption bands. However, a shift of the fundamental absorption spectrum cutoff appears after proton irradiation, but not in the case of the γ-irradiation. The observed shift of the band edge in the transmission spectrum following proton irradiation in lutetium oxyorthosilicate crystals indicates that this phenomenon is a general property of heavy crystalline materials. A possible proton-induced transmission damage mechanism is discussed.

  5. ^176Lu/^175Lu thermometry for Oklo natural reactors: a new look at old data

    NASA Astrophysics Data System (ADS)

    Gould, Chris; Sharapov, Eduard

    2012-03-01

    Lutetium thermometry has been used to analyze Oklo natural nuclear reactor zones but leads to widely varying and puzzling predictions for the temperatures TO, which in turn impacts Oklo bounds on the time variation of the fine structure constant α. We revisit results for reactor zone RZ10 in light of new astrophysical measurements of the isomer branching ratio B^g in ^175Lu neutron capture at 5 and 25 keV. We recalculate predictions for TO as a function of B^g using realistic models of the Oklo neutron flux. We find TO= 100 ±30 C using a new value of B^g, in contrast to 350 < TO< 500 C using the evaluated value at thermal energy. Lutetium thermometry can be applicable to analyses of Oklo reactor data, but a better measurement of B^g with thermal neutrons is needed to confirm the reliability of temperature predictions.

  6. Spectroscopic analysis of LYSO:Ce crystals

    NASA Astrophysics Data System (ADS)

    Martins, A. F.; Carreira, J. F. C.; Rodrigues, J.; Sedrine, N. Ben; Castro, I. F. C.; Correia, P. M. M.; Veloso, J. F. C. A.; Rino, L.; Monteiro, T.

    2017-02-01

    Rare earth orthosilicates are among the most widely used scintillator materials in the last decades. Particularly, lutetium-yttrium oxyorthosilicate (LYSO) is known to exhibit great potentialities in the field of radiation detectors for medical imaging. Consequently, an in-depth knowledge of the material properties is of utmost interest for the mentioned applications. In this work the spectroscopic properties of commercial cerium doped lutetium-yttrium oxyorthosilicate crystals (LYSO:Ce) were investigated by Raman spectroscopy, steady state photoluminescence, photoluminescence excitation and time resolved photoluminescence. Site selective excitation was used under steady state (325 nm) and pulsed (266 nm) conditions to separately investigate the temperature dependence of the 5d → 4f Ce1 and Ce2 luminescence, allowing to establish the thermal quenching dependence of the Ce2 optical center. In the case of the Ce1 optical center, a luminescence quantum efficiency of 78% was obtained from 14 K to room temperature with 266 nm photon excitation.

  7. Raman Spectra of High-κ Dielectric Layers Investigated with Micro-Raman Spectroscopy Comparison with Silicon Dioxide

    PubMed Central

    Borowicz, P.; Taube, A.; Rzodkiewicz, W.; Latek, M.; Gierałtowska, S.

    2013-01-01

    Three samples with dielectric layers from high-κ dielectrics, hafnium oxide, gadolinium-silicon oxide, and lanthanum-lutetium oxide on silicon substrate were studied by Raman spectroscopy. The results obtained for high-κ dielectrics were compared with spectra recorded for silicon dioxide. Raman spectra suggest the similarity of gadolinium-silicon oxide and lanthanum-lutetium oxide to the bulk nondensified silicon dioxide. The temperature treatment of hafnium oxide shows the evolution of the structure of this material. Raman spectra recorded for as-deposited hafnium oxide are similar to the results obtained for silicon dioxide layer. After thermal treatment especially at higher temperatures (600°C and above), the structure of hafnium oxide becomes similar to the bulk non-densified silicon dioxide. PMID:24072982

  8. Rare Earth Element Concentrations in Geothermal Wells at the Puna Geothermal Field, Hawaii

    DOE Data Explorer

    Fowler, Andrew; Zierenberg, Robert

    2016-12-09

    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.

  9. Isoselective 3,4-(co)polymerization of bio-renewable myrcene using NSN-ligated rare-earth metal precursor: an approach to a new elastomer.

    PubMed

    Liu, Bo; Li, Lei; Sun, Guangping; Liu, Dongtao; Li, Shihui; Cui, Dongmei

    2015-01-21

    The polymerization of bio-renewable myrcene (MY), using a cationic β-diimidosulfonate lutetium catalyst in high activity, afforded an unprecedented isotactic 3,4-polymyrcene (PMY) with a low Tg (-42 °C). Based on this result, the random and block copolymerization of myrcene and isoprene (IP) resulted in novel elastomers that comprise the amorphous iso-3,4-PMY and iso-3,4-PIP sequences.

  10. Low valency in lanthanides: A theoretical study of NdF and LuF

    SciTech Connect

    Schoendorff, George; Wilson, Angela K.

    2014-06-14

    The ground and low-lying excited state potential energy curves of neodymium monofluoride were calculated using multireference (CASSCF) and single reference (EOM-CR-CCSD(T)) methods. Optimized bond lengths were obtained and accurate bond dissociation energies were computed. The EOM-CR-CCSD(T) method was used to determine the bond dissociation energy of lutetium monofluoride, and it is shown that core correlation is required to produce bond dissociation energies in agreement with experiment.

  11. A new polymorph of Lu(PO(3))(3).

    PubMed

    Bejaoui, Anis; Horchani-Naifer, Karima; Férid, Mokhtar

    2008-07-19

    A new polymorph of lutetium polyphosphate, Lu(PO(3))(3), was found to be isotypic with the trigonal form of Yb(PO(3))(3). Two of the three Lu atoms occupy special positions (Wyckoff positions 3a and 3b, site symmetry ). The atomic arrangement consists of infinite helical polyphosphate chains running along the c axis, with a repeat period of 12 PO(4) tetra-hedra, joined with LuO(6) octa-hedra.

  12. Method for preparing high specific activity 177Lu

    DOEpatents

    Mirzadeh, Saed; Du, Miting; Beets, Arnold L.; Knapp, Jr., Furn F.

    2004-04-06

    A method of separating lutetium from a solution containing Lu and Yb, particularly reactor-produced .sup.177 Lu and .sup.177 Yb, includes the steps of: providing a chromatographic separation apparatus containing LN resin; loading the apparatus with a solution containing Lu and Yb; and eluting the apparatus to chromatographically separate the Lu and the Yb in order to produce high-specific-activity .sup.177 Yb.

  13. Rare Earth Element Concentrations from Wells at the Don A. Campbell Geothermal Plant, Nevada

    DOE Data Explorer

    Fowler, Andrew; Zierenberg, Robert

    2016-12-09

    * 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.

  14. Lanthanide Diphthalocyanines. Electrochemistry and Display Applications.

    DTIC Science & Technology

    1982-01-01

    and porphyrins, the diphthalocyanines might serve as dimeric model compounds for research on natural products. This article provides a survey and... model also fit the galvanostatic transient data, with an ionic space charge in the red phase as the rate-controlling factor. Potentiostatic transients...out essentially complete electrolyses of lutetium diphthalocyanine dissolved in 014F and examined the initial and final solutions by absorption

  15. First principle calculation of structure and lattice dynamics of Lu2Si2O7

    NASA Astrophysics Data System (ADS)

    Nazipov, D. V.; Nikiforov, A. E.

    2016-12-01

    Ab initio calculations of crystal structure and Raman spectra has been performed for single crystal of lutetium pyrosilicate Lu2Si2O7. The types of fundamental vibrations, their frequencies and intensities in the Raman spectrum has been obtained for two polarizations. Calculations were made in the framework of density functional theory (DFT) with hybrid functionals. The isotopic substitution was calculated for all inequivalent ions in cell. The results in a good agreement with experimental data.

  16. Ce-doped single crystal and ceramic garnets for γ ray detection

    SciTech Connect

    Hull, G; Roberts, J; Kuntz, J; Fisher, S; Sanner, R; Tillotson, T; Drobshoff, A; Payne, S; Cherepy, N

    2007-07-30

    Ceramic and single crystal Lutetium Aluminum Garnet scintillators exhibit energy resolution with bialkali photomultiplier tube detection as good as 8.6% at 662 keV. Ceramic fabrication allows production of garnets that cannot easily be grown as single crystals, such as Gadolinium Aluminum Garnet and Terbium Aluminum Garnet. Measured scintillation light yields of Cerium-doped ceramic garnets indicate prospects for high energy resolution.

  17. Lattice dynamics of LuPO{sub 4}

    SciTech Connect

    Nipko, J.C. |; Loong, C.-K.; Loewenhaupt, M.; Reichardt, W.; Braden, M.; Boatner, L.A.

    1996-06-01

    Lutetium orthophosphate is an important nonmagnetic host material for rare-earth-activated luminescence applications. We have measured the LuPO{sub 4} phonon density of states and dispersion curves along the [{xi}00],[{xi}{xi}0], and [00{xi}] symmetry directions by neutron spectroscopy using polycrystalline and single-crystal samples. A quantitative analysis of the neutron results was carried out using a lattice-dynamical shell model.

  18. Resonance ionization mass spectrometry for isotopic abundance measurements

    NASA Technical Reports Server (NTRS)

    Miller, C. M.

    1986-01-01

    Resonance ionization mass spectrometry (RIMS) is a relatively new laser-based technique for the determination of isotopic abundances. The resonance ionization process depends upon the stepwise absorption of photons from the laser, promoting atoms of the element of interest through progressively higher electronic states until an ion is formed. Sensitivity arises from the efficiency of the resonant absorption process when coupled with the power available from commercial laser sources. Selectivity derives naturally from the distinct electronic structure of different elements. This isobaric discrimination has provided the major impetus for development of the technique. Resonance ionization mass spectrometry was used for analysis of the isotopic abundances of the rare earth lutetium. Isobaric interferences from ytterbium severely effect the ability to measure small amounts of the neutron-deficient Lu isotopes by conventional mass spectrometric techniques. Resonance ionization for lutetium is performed using a continuous-wave laser operating at 452 nm, through a sequential two-photon process, with one photon exciting the intermediate resonance and the second photon causing ionization. Ion yields for microgram-sized quantities of lutetium lie between 10(6) and 10(7) ions per second, at overall ionization efficiencies approaching 10(-4). Discrimination factors against ytterbium greater than 10(6) have been measured. Resonance ionization for technetium is also being explored, again in response to an isobaric interference, molybdenum. Because of the relatively high ionization potential for Tc, three-photon, two-color RIMS processes are being developed.

  19. A density functional theory investigation for the open-shell metal-carbide endofullerene Lu3C2@C88(D2:35) and closed-shell metal-nitride endofullerene Lu3N@C88(D2:35).

    PubMed

    Wu, Jing-Yi; Xu, Wei; Wang, Tai-Shan; Jiang, Li; Shu, Chun-Ying; Wang, Chun-Ru

    2012-03-01

    By means of the density functional theory calculations, two C88(D2:35)-based endohedral fullerenes, Lu3C2@C88(D2:35) and Lu3N@C88(D2:35) which encapsulate tri-lutetium carbide and tri-lutetium nitride cluster were investigated. For the cores in Lu3C2@C88 and Lu3N@C88, the trivalent C2 and N respectively template a butterfly-shaped endohedral moiety and a planar tri-lutetium cluster within the same D2-symmetric C88 cage. Moreover, Lu3N@C88 - D2 has a closed-shell electronic structure but for LuC3C2@C88 - D2, it owns an unpaired electron mainly localized on the internal Lu3C2 cluster. These results clearly showed that the core unit C2(3) as well as N3- play an important role in constructing molecular structures and electronic features of metallofullerenes. Furthermore, the electrochemical redox potentials, and vibrational frequencies of the two endofullerenes agree well with our experimental results. The electronic structures, ionization energies, electron affinities, inner clusters' dynamic motions of them have been predicted to further disclose the characters of these two metallofullerenes.

  20. Spectral and structural characteristics of Lu1 - x - y Ce x Tb y BO3 orthoborates prepared by the hydrothermal synthesis method

    NASA Astrophysics Data System (ADS)

    Shmurak, S. Z.; Kedrov, V. V.; Kiselev, A. P.; Fursova, T. N.; Rybchenko, O. G.

    2017-06-01

    The structure, IR absorption spectra, morphology, and photoluminescence spectral characteristics of Lu1- x- y Ce x Tb y BO3 solid solutions prepared by the hydrothermal synthesis method have been investigated. According to the X-ray powder diffraction data, the Lu1- x- y Ce x Tb y BO3 samples hydrothermally synthesized at a temperature T = 200°C have the vaterite structure, and all the observed diffraction peaks correspond to the hexagonal phase with the space group P63/ mmc, which is isostructural to pure lutetium borate LuBO3. Annealing of these samples at T = 970°C leads to a change in the structural modification and to the transition of the samples to the monoclinic phase with the space group C2/ c. It has been found that, after annealing of these samples at temperatures T = 800-970°C, the luminescence intensity of Tb3+ ions upon excitation in the absorption band of Ce3+ ions increases by more than two orders of magnitude and becomes much higher than that in compounds of the same composition, but prepared by high-temperature synthesis. At the same time, annealing of lutetium borate doped only with terbium does not lead to a significant change in the luminescence intensity of Tb3+ ions. The possible reasons for a multiple increase in the luminescence intensity of terbium ions due to the annealing of the hydrothermally synthesized lutetium orthoborate samples doped with cerium and terbium ions have been discussed.

  1. Crystalline rare-earth activated oxyorthosilicate phosphor

    DOEpatents

    McClellan, Kenneth J.; Cooke, D. Wayne

    2004-02-10

    Crystalline, transparent, rare-earth activated lutetium oxyorthosilicate phosphor. The phosphor consists essentially of lutetium yttrium oxyorthosilicate activated with a rare-earth metal dopant M and having the general formula Lu(.sub.2-x-z)Y.sub.x M.sub.z SiO.sub.5, wherein 0.00.ltoreq.x.ltoreq.1.95, wherein 0.001.ltoreq.z.ltoreq.0.02, and wherein M is selected from Sm, Tb, Tm, Eu, Yb, and Pr. The phosphor also consists essentially of lutetium gadolinium oxyorthosilicate activated with a rare-earth metal dopant M and having the general formula Lu(.sub.2-x-z)Gd.sub.x M.sub.z SiO.sub.5, wherein 0.00.ltoreq.x.ltoreq.1.95, wherein 0.001.ltoreq.z.ltoreq.0.02, and wherein M is selected from Sm, Tb, Tm, Eu, Yb, and Pr. The phosphor also consists essentially of gadolinium yttrium oxyorthosilicate activated with a rare-earth metal dopant M and having the general formula Gd(.sub.2-x-z)Y.sub.x M.sub.z SiO.sub.5, wherein 0.00.ltoreq.x.ltoreq.1.95, wherein 0.001.ltoreq.z.ltoreq.0.02, and wherein M is selected from Sm, Tb, Tm, Eu, Yb, and Pr. The phosphor may be optically coupled to a photodetector to provide a radiation detector.

  2. Trimethylsilylmethyl complexes of the rare-earth metals with sterically hindered N-heterocyclic carbene ligands: adduct formation and C-H bond activation.

    PubMed

    Fegler, Waldemar; Spaniol, Thomas P; Okuda, Jun

    2010-08-07

    Tris(trimethylsilylmethyl) complexes of yttrium and lutetium [LnR(3)(THF)(2)] (R = CH(2)SiMe(3)) were treated with sterically bulky N-heterocyclic carbenes (NHC) 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) and 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes). IPr gave labile mono-adducts [LnR(3)(NHC)], isolated as thermally robust crystals and fully characterized by NMR spectroscopy and X-ray diffraction. IMes gave a similar lutetium mono-adduct [LuR(3)(IMes)] with the lutetium alkyl [LuR(3)(THF)(2)], whereas the yttrium alkyl [YR(3)(THF)(2)] resulted in the formation of an ortho-metalated product. This compound, isolated as a crystalline bis(THF) adduct, contains a strained six-membered chelate ring that has been formed by the C-H bond activation of one of the ortho-methyl groups of the mesityl group. In contrast [LuR(3)(IMes)] only slowly underwent a similar C-H bond activation.

  3. Raman and structural characterization of LuAlO{sub 3}

    SciTech Connect

    Casu, Alberto; Ricci, Pier Carlo

    2011-11-15

    The structural and vibrational properties of lutetium orthoaluminate perovskite (LuAlO{sub 3}) were investigated by means of Raman spectroscopy and EXAFS measurements. The analysis of Raman spectra taken in four different polarized configurations along the principal axes at 20 K and room temperature conditions permits to assign the principal vibrational modes in LuAP single crystals and to confirm the belonging to the D{sub 2h}{sup 16} space group. EXAFS measurements were performed at room temperature in order to obtain local structural informations on the first and next nearest neighbors around lutetium absorptions sites. Unit cell parameters and bond lengths were determined by the analysis of the EXAFS spectroscopy at the L{sub 3} absorption edge of lutetium. The informations thus gathered on this compound can offer a useful addition in the framework of a full structural characterization of LuAlO{sub 3}. - Graphical abstract: Raman active mode in LuAP crystal. Highlights: > Structural characterization of LuAlO{sub 3} is obtained by Raman and EXAFS spectroscopies. > Vibrational modes, temperature-dependent variations studied by Raman spectroscopy. > Cell parameters and local characterization obtained by EXAFS spectroscopy.

  4. 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 %.

  5. Microstructure, microhardness, phase analysis and chemical composition of laser remelted FeB-Fe2B surface layers produced on Vanadis-6 steel

    NASA Astrophysics Data System (ADS)

    Bartkowska, Aneta; Swadźba, Radosław; Popławski, Mikołaj; Bartkowski, Dariusz

    2016-12-01

    The paper presents the study results of the diffusion boronized layer and their laser modification. Diffusion boronized processes were carried out on Vanadis-6 steel at 900 °C for 5 h. Boronized layers were characterized by dual-phase microstructure consisting of iron borides having a microhardness in the range from 1800 to 1400 HV. The laser heat treatment was carried out using CO2 laser after diffusion boronizing process. The research goals of this paper was analysis of microstructure, microhardness as well as phase and chemical composition of boronized layers after laser modification. Microstructure of boronized layer after laser modification consisted of remelted zone, heat affected zone and substrate. Remelted zone was characterized by microstructure consisted of boron-martensite eutectic. In this zone, the phases of borides and carbides were detected. Boronized layers after laser modification were characterized by the mild gradient of microhardness from surface to the substrate.

  6. Anomalous Stress Response of Ultrahard WBn Compounds

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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 WBn (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 distinct type of ultrahard material. These new insights underscore the need to explore unconventional structure-property relations in a broad range of transition-metal light-element compounds.

  7. Perspectives of High-Temperature Thermoelectric Applications and p-type and n-type Aluminoborides

    NASA Astrophysics Data System (ADS)

    Mori, T.

    2016-10-01

    A need exists to develop high-temperature thermoelectric materials which can utilize high-temperature unutilized/waste heat in thermal power plants, steelworks, factories, incinerators, etc., and also focused solar power. The thermal power plant topping application is of potential high impact since it can sizably increase the efficiency of power plants which are the major supply of electrical power for many countries. Higher borides are possible candidates for their particular high-temperature stability, generally large Seebeck coefficients, α, and intrinsic low thermal conductivity. Excellent (|α| > 200 μV/K) p-type or n-type behavior was recently achieved in the aluminoboride YAl x B14 by varying the occupancy of Al sites, x. Finding p-type and n-type counterparts has long been a difficulty of thermoelectric research not limited to borides. This paper reviews possible high-temperature thermoelectric applications, and recent developments and perspectives of thermoelectric aluminoborides.

  8. Electric arc surfacing on low carbon steel: Structure and properties

    NASA Astrophysics Data System (ADS)

    Ivanov, Yurii; Gromov, Victor; Kormyshev, Vasilii; Konovalov, Sergey; Kapralov, Evgenii; Semin, Alexander

    2016-11-01

    By the methods of modern materials science, the structure-phase state and microhardness distribution along the cross-section of single and double coatings surfaced on martensite low carbon steel by alloy powder-cored wire were studied. It was established that the increased mechanical properties of surfaced layer are determined by the sub-micro and nanodispersed martensite structure formation, containing iron borides forming the eutectic of lamellar form. The plates of Fe2B are formed mainly in the eutectic of a single-surfaced layer, while FeB is formed in a double-surfaced layer. The existence of bend extinction contours indicating the internal stress fields formation at the boundaries of Fe borides-α-Fe phases were revealed.

  9. Anomalous stress response of ultrahard WBn compounds

    SciTech Connect

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

    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 WBn (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 distinct 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.

  10. Anomalous stress response of ultrahard WBn 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 WBn (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 distinct typemore » 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

  11. 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.

  12. High intrinsic coercivities in iron-rare earth-carbon-boron alloys through the carbide or boro-carbide Fe14R2X (X=BxC1-x)

    NASA Astrophysics Data System (ADS)

    Liu, N. C.; Stadelmaier, H. H.; Schneider, G.

    1987-04-01

    In the phase Fe14R2X, where R is a lanthanide and X is either boron or carbon, or a mixture of the two, the extent of stability of the carbides and their miscibility with the borides is traced for the lighter rare-earth metals. Like the borides, the carbides are magnetically hard, but unlike them, they do not normally crystallize from the melt, and this property is exploited to produce intrinsic coercivities above 12 kOe in cast materials without the added special processing step of sintering or melt spinning. The high coercivity is related to a cellular microstructure of Fe14R2X in which the cell size is approximately 1 μm. The cell structure, which originates in a peritectoidlike transformation from primary Fe17R2, is quite stable and does not change during prolonged annealing. The coercivity is sensitive to variations in composition.

  13. 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.

  14. Modeling of substrate bias effect on the compositional variations in sputtered-deposited TiB{sub 2+x} diffusion barrier thin films

    SciTech Connect

    Sinder, M.; Sade, G.; Pelleg, J.

    1998-12-31

    Sputter-deposited titanium boride diffusion barrier layers have been found to be boron enriched when r.f. substrate bias was applied. In the present experiments titanium boride was deposited by co-sputtering from Ti and B pure targets in Ar discharge and the voltage of r.f. self-bias was in the range of 100--250 V. Films deposited were found by Auger electron spectroscopy to be B enriched with increasing bias voltage at constant Ti and B sputtering rates. A model of the sputter-deposition conditions was developed to predict the composition and the thickness of the growing film. The model explains the experimental results indicating that B enrichment is mainly a result of differential resputtering of the components from the growing film by energetic Ar ions capture from the r.f. discharge.

  15. Microstructure and selected properties of boronized layers produced on C45 and CT90 steels after modification by diode laser

    NASA Astrophysics Data System (ADS)

    Bartkowska, Aneta; Bartkowski, Dariusz; Przestacki, Damian; Talarczyk, Małgorzata

    2016-12-01

    The paper presents the study results of macro- and microstructure, microhardness and corrosion resistance of C45 medium carbon steel and CT90 high carbon steel after diffusion boriding and laser modification by diode laser. It was found that the increase of carbon content reduced the thickness of boronized layer and caused change in their morphology. Diffusion boronized layers were composed of FeB and Fe2B iron borides. As a result of laser surface modification of these layers, the microstructure composed of three areas: remelted zone, heat affected zone (HAZ) and the substrate was obtained. Microhardness of laser remelting boronized layer in comparison with diffusion boronized layer was lower. The presence of HAZ was advantageous, because mild microhardness gradient between the layer and the substrate was assured. The specimens with laser boronized layers were characterized by better corrosion resistance than specimens without modified layer.

  16. Plasmadynamic synthesis of Ti-B nanopowders

    NASA Astrophysics Data System (ADS)

    Nikitin, D.; Sivkov, A.; Gerasimov, D.; Evdokimov, A.

    2017-05-01

    Ti-B nanopowders were produced by plasmadynamic synthesis. This method was implemented by the synthesis in an electrodischarge plasma jet generated by a high-current pulsed coaxial magnetoplasma accelerator. Two experiments were carried out using copper and titanium conductors for initiating the plasma jet. The synthesized products were analyzed by several modern techniques including X-ray diffractometry and transmission electron microscopy. The variety of crystalline phases in the products of both Ti-B and Ti-O systems were identified. The most successful results were obtained using titanium conductors. In this case, the product mainly contains titanium boride and titanium diboride. Synthesized powder consists of hexagonal and cubic particles, which were identified as titanium boride and titanium diboride particles, respectively. The method using titanium conductors for initiating the plasma jet is more efficient and simple way for obtaining TiB/TiB2 nanopowders.

  17. The Analysis and Modeling of Phase Stability and Multiphase Designs in High Temperature Refractory Metal-Silicon-Boron Alloys

    DTIC Science & Technology

    2009-01-27

    to exhibit segregation and non-equilibrium boride phases that are difficult to remove by annealing or hot working. Initial efforts in powder...and hot isostatic pressing to react the components [06JEH, 04JEH]. Following synthesis, the microstructure retained a sub micron phase size and...moreover exhibited superplastic behavior at 1400°C. This observation indicates the possibility for fabricating final shapes by hot forging. However

  18. ONR (Office of Naval Research) Far East Scientific Information Bulletin. Volume 14, Number 2, April-June 1989

    DTIC Science & Technology

    1989-06-01

    carbides and borides on an alloy deposition from the gas phase. Surface surface); and (2) synthesis of new materials precipitation is also being studied...breeder * Analysis of Damage/Endurance Relation- reactors, and high temperature gas -cooled ships in Structural Materials for High reactors. Cyclotron... materials used in 1988), pp 733-742. gas turbines. In the past this market has not been available to the Japanese except for 8. H. Onodera, K. Ohno, T

  19. 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.

  20. 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.