WorldWideScience

Sample records for dysprosium borides

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

    Science.gov (United States)

    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

  2. Method for ultra-fast boriding

    Energy Technology Data Exchange (ETDEWEB)

    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.

  3. Kinetics of borided gear steels

    Indian Academy of Sciences (India)

    Ibrahim Gunes

    2013-06-01

    In this study, the case properties and diffusion kinetics of GS18NiMoCr36 (GS18), GS22NiMoCr56 (GS22) and GS32NiCrMo6.4 (GS32) gear steels borided in Ekabor-II powder were investigated by conducting a series of experiments at temperatures of 1123, 1173 and 1223 K for 2, 4 and 6 h. The boride layer was characterized by optical microscopy, X-ray diffraction technique and microVickers hardness tester. X-ray diffraction analysis of boride layers on the surface of the steels revealed the existence of FeB, Fe2B, CrB and Cr2B compounds. The thickness of the boride layer increases by increasing boriding time and temperature for all steels. The hardness of the boride compounds formed on the surface of the steels GS18, GS22 and GS32 ranged from 1624 to 1905 HV0,05, 1702 to 1948 HV0,05, and 1745 to 2034 HV0,05 respectively, whereas Vickers hardness values of the untreated steels GS18, GS22 and GS32 were 335 HV0,05, 358 HV0,05 and 411 HV0,05, respectively. The activation energies (Q) of borided steels were 228.644 kJ/mol for GS18, 280.609 kJ/mol for GS22 and 294.359 kJ/mol for GS32. The growth kinetics of the boride layers forming on the GS18, GS22 and GS32 steels and the thickness of boride layers were also investigated.

  4. Microstructure and of Mechanics Microwave Boriding

    Institute of Scientific and Technical Information of China (English)

    YE Weiping; HUANG Zilin; ZHANG Qiaoxin; ZHANG Qinyi

    2008-01-01

    Microwave boriding layer microstructure of carbon steels and its diffusion mechanics were studied.The results show that the existence of microwave field in the boriding can't change the growth mechanics of boriding layer. Compared with conventional boriding,if the treatment temperature and time remain constantly,the descend rate of the boriding layer thickness with the increase of carbon content of steel is smaller.The diffusion activation energy of T8 steel is 2.6× 105 J/mol between the temperature of 750 ℃and 900 ℃ in microwave field,which is in the same order ofconventional boriding.

  5. Nanodispersed boriding of titanium alloy

    Directory of Open Access Journals (Sweden)

    Kateryna O. Kostyk

    2015-12-01

    Full Text Available The problem of improving the operational reliability of machines is becoming increasingly important due to the increased mechanical, thermal and other loads on the details. There are many surface hardening methods for machines parts which breakdown begins with surface corruption. The most promising methods are chemo-thermal treatment. Aim: The aim of this work is to study the impact of boriding on the structure and properties of titanium alloy. Materials and Methods: The material of this study is VT3-1 titanium alloy. The boriding were conducted using nanodispersed powder blend based on boric substances. Results: It is established that boriding of paste compounds allows obtaining the surface hardness within 30...29 GPa and with declining to 27...26 GPa in layer to the transition zone (with total thickness up to 110 μm owing to changes of the layer phase composition where Ti2B, TiB, TiB2 titanium borides are formed. The increasing of chemical-thermal treatment time from 15 minutes to 2 hours leads to thickening of the borated layer (30...110 µm and transition zone (30...190 µm. Conclusions: Due to usage of nanodispersed boric powder, the boriding duration is decreasing in 2...3 times. This allows saving time and electric energy. The developed optimal mode of boriding the VT3-1 titanium alloy allows obtaining the required operational characteristics and to combine the saturation of the surface layer with atomic boron and hardening.

  6. Rediscovering the Crystal Chemistry of Borides.

    Science.gov (United States)

    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.

  7. Boriding of Binary Ni-Ti Shape Memory Alloys

    Science.gov (United States)

    Ucar, Nazim; Dogan, Sule; Karakas, Mustafa Serdar; Calik, Adnan

    2016-11-01

    Boriding of binary Ni-Ti shape memory alloys was carried out in a solid medium at 1273 K for 2, 4, 6, and 8 h using the powder pack method with proprietary Ekabor-Ni powders. Characterization of the boride layer formed on the surface of alloys was done by optical microscopy and scanning electron microscopy. The presence of boride, silicide, and borosilicide phases in the boride layers was confirmed by X-ray diffraction analysis. The thickness and microhardness of the boride layers increased with increasing boriding time. Hardness profiles showed a rapid decrease in hardness moving from the boride layer to the main structure. The high hardness of the boride layer was attributed mainly to the formation of TiB2. A parabolic relationship was observed between layer thickness and boriding time, and the growth rate constant for the boriding treatment was calculated as 0.62×10-8 cm2 s-1.

  8. Dysprosium magneto-optical traps

    CERN Document Server

    Youn, Seo Ho; Ray, Ushnish; Lev, Benjamin L

    2010-01-01

    Magneto-optical traps (MOTs) of highly magnetic lanthanides open the door to explorations of novel phases of strongly correlated matter such as lattice supersolids and quantum liquid crystals. We recently reported the first MOTs of the five high abundance isotopes of the most magnetic atom, dysprosium. Described here are details of the experimental technique employed for repumper-free Dy MOTs containing up to half a billion atoms. Extensive characterization of the MOTs' properties---population, temperature, loading, metastable decay dynamics, trap dynamics---is provided.

  9. Magnesium Aluminum Borides as Explosive Materials

    Science.gov (United States)

    2011-12-20

    Figure 1). Hsia argued that compounds that do not undergo decomposition reactions are better choices for rocket propellants since the endothermic ...decomposition reaction is undesired. The endotherm for AlB2 decomposition, however, is small[13], especially when compared to the heat of combustion... exotherms for the boron carbide materials are comparable to those of Al + 2B and AlB2. 40 Figure 23. TGA of silicon borides vs . aluminum borides

  10. Characterization of AISI 4140 borided steels

    Energy Technology Data Exchange (ETDEWEB)

    Campos-Silva, I., E-mail: icampos@ipn.mx [Instituto Politecnico Nacional, Grupo Ingenieria de Superficies, SEPI-ESIME U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F., 07738 (Mexico); Ortiz-Dominguez, M.; Lopez-Perrusquia, N.; Meneses-Amador, A. [Instituto Politecnico Nacional, Grupo Ingenieria de Superficies, SEPI-ESIME U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F., 07738 (Mexico); Escobar-Galindo, R. [Instituto de Ciencia de Materiales de Madrid (CSIC), E-28049 Cantoblanco, Madrid (Spain); Martinez-Trinidad, J. [Instituto Politecnico Nacional, Grupo Ingenieria de Superficies, SEPI-ESIME U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F., 07738 (Mexico)

    2010-02-01

    The present study characterizes the surface of AISI 4140 steels exposed to the paste-boriding process. The formation of Fe{sub 2}B 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{sub 2}B 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 {mu}m 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 K{sub C}({pi}/2) > K{sub C} > K{sub C}(0) for the different applied loads and experimental parameters of the boriding process.

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

    Science.gov (United States)

    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.

  12. On polymorphism of dysprosium trichloride

    Energy Technology Data Exchange (ETDEWEB)

    Zakiryanova, Irina D.; Khokhlov, Vladimir A.; Salyulev, Alexander B.; Korzun, Iraida V. [RAS Ural Branch, Ekaterinburg (Russian Federation). Institute of High-Temperature Electrochemistry

    2015-07-01

    For the first time, the structure of crystalline DyCl{sub 3} over a wide temperature range from room temperature to melting point was studied by Raman spectroscopy. The phonon modes (cm{sup -1}) of dysprosium trichloride (monoclinic crystal lattice of AlCl{sub 3} type, Z = 4, CN = 6) at room temperature are 257 (A{sub 1g}), 201 (E{sub g}), 112 (E{sub g}), 88 (A{sub 1g}), and 63 (E{sub g}). The monoclinic structure of the crystalline DyCl{sub 3} C{sub 2h}{sup 3} symmetry was found to remain constant over the studied temperature range. No polymorphic transformation in the solid state was detected. Gravimetry, calorimetry, and mass spectrometry have been used in addition to support the conclusions made on the basis of Raman spectroscopic data.

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

    Science.gov (United States)

    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.

  14. Resonance ionization spectroscopy in dysprosium

    Energy Technology Data Exchange (ETDEWEB)

    Studer, D., E-mail: dstuder@uni-mainz.de; Dyrauf, P.; Naubereit, P.; Heinke, R.; Wendt, K. [Johannes Gutenberg-Universität Mainz, Institut für Physik (Germany)

    2017-11-15

    We report on resonance ionization spectroscopy (RIS) of high-lying energy levels in dysprosium. We developed efficient excitation schemes and re-determined the first ionization potential (IP) via analysis of Rydberg convergences. For this purpose both two- and three-step excitation ladders were investigated. An overall ionization efficiency of 25(4) % could be demonstrated in the RISIKO mass separator of Mainz University, using a three-step resonance ionization scheme. Moreover, an extensive analysis of the even-parity 6sns- and 6snd-Rydberg-series convergences, measured via two-step excitation was performed. To account for strong perturbations in the observed s-series, the approach of multichannel quantum defect theory (MQDT) was applied. Considering all individual series limits we extracted an IP-value of 47901.76(5) cm{sup −1}, which agrees with the current literature value of 47901.7(6) cm{sup −1}, but is one order of magnitude more precise.

  15. Characterization of rough interfaces obtained by boriding

    Energy Technology Data Exchange (ETDEWEB)

    Campos-Silva, I. [Instituto Politecnico Nacional, SEPI-ESIME, U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F. 07738 (Mexico)], E-mail: icampos@ipn.mx; Balankin, A.S. [Instituto Politecnico Nacional, SEPI-ESIME, U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F. 07738 (Mexico); Sierra, A.H. [Instituto Politecnico Nacional, UPIICSA, Av. Te 950, Col Granjas, Mexico D.F. 08400 (Mexico); Lopez-Perrusquia, N. [Instituto Politecnico Nacional, SEPI-ESIME, U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F. 07738 (Mexico); Escobar-Galindo, R. [Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, Madrid E-28049 (Spain); Morales-Matamoros, D. [Instituto Mexicano del Petroleo, Eje Lazaro Cardenas Norte, Mexico D.F. 07738 (Mexico)

    2008-12-30

    This study evaluates the morphology of borided interfaces by means of the fractal theory. The boride layers were formed in the AISI M2 steel by applying the paste boriding treatment at temperatures of 1253 and 1273 K and treatment times of 2 and 6 h, while a boron carbide paste thickness of 4 or 5 mm covered the samples surface in order to produce the boron diffusion. The morphology of interfaces formed between FeB and Fe{sub 2}B layers and between Fe{sub 2}B layer and steel substrate was analyzed by the rescaled-range (R/S), root-mean-square (RMS), and Fourier power spectrum (FPS) methods. Moreover, the multi-affine spectra of roughness exponent were obtained by calculating the q-order height-height correlation functions. We found that both interfaces are multi-affine, rather than self-affine. The multi-affine spectra of roughness exponents are found to be different for FeB/Fe{sub 2}B and Fe{sub 2}B/substrate interfaces, but independent on the treatment parameters (boron carbide paste thickness, temperature, and boriding time). Furthermore, we found that the multi-affine spectra of both interfaces behave as it is expected for 'universal multi-fractals' with the Levy index {gamma} = 1, associated with the multiplicative cascades with a log-Cauchy distribution. Furthermore, our data suggest a great homogeneity of the boron diffusion field, characterized by universal fractal dimension D{sub diff} = 2.90 {+-} 0.01. These findings provide a novel insight into the nature of phase formation during the boriding treatment.

  16. Boriding of binary Ni-Ti shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ucar, Nazim; Dogan, Sule [Suleyman Demirel Univ., Isparta (Turkey). Physics Dept.; Karakas, Mustafa Serdar [Cankaya Univ., Ankara (Turkey). Materials Science and Engineering Dept.; Calik, Adnan [Suleyman Demirel Univ., Isparta (Turkey). Manufacturing Engineering Dept.

    2016-07-01

    Boriding of binary Ni-Ti shape memory alloys was carried out in a solid medium at 1273 K for 2, 4, 6, and 8 h using the powder pack method with proprietary Ekabor-Ni powders. Characterization of the boride layer formed on the surface of alloys was done by optical microscopy and scanning electron microscopy. The presence of boride, silicide, and borosilicide phases in the boride layers was confirmed by X-ray diffraction analysis. The thickness and microhardness of the boride layers increased with increasing boriding time. Hardness profiles showed a rapid decrease in hardness moving from the boride layer to the main structure. The high hardness of the boride layer was attributed mainly to the formation of TiB{sub 2}. A parabolic relationship was observed between layer thickness and boriding time, and the growth rate constant for the boriding treatment was calculated as 0.62 x 10{sup -8} cm{sup 2}s{sup -1}.

  17. Investigation of the fracture mechanics of boride composites

    Science.gov (United States)

    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.

  18. The dysprosium-tin phase diagram

    Energy Technology Data Exchange (ETDEWEB)

    Eremenko, V.N.; Bulanova, M.V.; Martsenjuk, P.S. (I.N. Frantsevich Inst. for Problems of Materials Science, Kiev (Ukraine))

    1992-12-07

    The dysprosium-tin phase diagram was established by means of differential thermal, X-ray and microscopic analyses of 22 alloys. Seven intermetallic compounds were found to exist in the system. Dy[sub 5]Sn[sub 3] melts congruently at 1870 degC, and undergoes a polymorphous transformation at 1823 [+-] 6 degC. The intermetallics Dy[sub 5]Sn[sub 4], Dy[sub 11]Sn[sub 10], DySn, Dy[sub 4]Sn[sub 5], DySn[sub 2], DySn[sub 3] are formed peritectically at 1712 [+-]11, 1605 [+-]12, 1208 [+-]3, 1166 [+-]7, 1138 [+-]3 and 747 [+-]6 degC respectively. DySn[sub 3] exists in a narrow temperature range, in two polymorphous modifications. The transformation [beta]-DySn[sub 3] [yields] [alpha]-DySn[sub 3] occurs at 608 [+-] 12 degC, and at 499 [+-]2 degC [alpha]-DySn[sub 3] decomposes to DySn[sub 2] and the tin-rich melt. The dysprosium-rich eutectic crystallizes at 1204 [+-]10 degC and contains 13 at.% tin. The solid-state solubility of tin in dysprosium is about 3 at.%, and that of dysprosium in tin is negligible.

  19. Towards a new measurement of parity violation in dysprosium

    CERN Document Server

    Leefer, N; Antypas, D; Budker, D

    2014-01-01

    The dysprosium parity violation experiment concluded nearly 17 years ago with an upper limit on weak interaction induced mixing of nearly degenerate, opposite parity states in atomic dysprosium. While that experiment was limited in sensitivity by statistics, a new apparatus constructed in the interim for radio-frequency spectroscopy is expected to provide significant improvements to the statistical sensitivity. Preliminary work from the new PV experiment in dysprosium is presented with a discussion of the current statistical sensitivity and outlook.

  20. Dysprosium Modification of Cobalt Ferrite Ionic Magnetic Fluids

    Institute of Scientific and Technical Information of China (English)

    JIANG Rong-li; LIU Yong-chao; GENG Quan-rong; ZHAO Wen-tao

    2005-01-01

    Dysprosium composite cobalt ferrite ionic magnetic fluids were prepared by precipitation in the presence of Tri-sodium citrate. Influence of dysprosium modification on magnetic property is studied. The result shows that magnetic response toward exterior magnetic field can be improved by adding Dy3+. Studies also show that the increase of reaction temperature may improve the modification effect of dysprosium. By adding dysprosium ions, the average diameter of the magnetic nanoparticles will be decreased evidently. It is clear that the particles appear as balls, Cobalt ferrite with sizes of 12-15 nm, rare earth composite cobalt ferrite with sizes of 6-8 nm.

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

    Science.gov (United States)

    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.

  2. Can a dysprosium shortage threaten green energy technologies?

    NARCIS (Netherlands)

    Hoenderdaal, S.; Tercero Espinoza, L.; Marschneider-Weidemann, F.; Crijns - Graus, Wina

    2013-01-01

    Dysprosium, one of the various rare earth elements, is currently for more than 99% mined in China. As China is reducing its exports, new mining projects outside of China are needed to sustain supply and meet future demands. Dysprosium is mainly used in permanent magnets to retain the magnet's streng

  3. Plasma metallurgical production of nanocrystalline borides and carbides

    Science.gov (United States)

    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.

  4. Phenalenyl-based mononuclear dysprosium complexes

    Directory of Open Access Journals (Sweden)

    Yanhua Lan

    2016-07-01

    Full Text Available The phenalenyl-based dysprosium complexes [Dy(PLN2(HPLNCl(EtOH] (1, [Dy(PLN3(HPLN]·[Dy(PLN3(EtOH]·2EtOH (2 and [Dy(PLN3(H2O2]·H2O (3, HPLN being 9-hydroxy-1H-phenalen-1-one, have been synthesized. All compounds were fully characterized by means of single crystal X-ray analysis, paramagnetic 1H NMR, MALDI-TOF mass spectrometry, UV–vis spectrophotometry and magnetic measurements. Both static (dc and dynamic (ac magnetic properties of these complexes have been investigated, showing slow relaxation of magnetization, indicative of single molecule magnet (SMM behavior. Attempts to synthesize sublimable phenalenyl-based dysprosium complexes have been made by implementing a synthetic strategy under anhydrous conditions. The sublimed species were characterized and their thermal stability was confirmed. This opens up the possibility to deposit phenalenyl-based lanthanides complexes by sublimation onto surfaces, an important prerequisite for ongoing studies in molecular spintronics.

  5. Anisotropy in the Interaction of Ultracold Dysprosium

    CERN Document Server

    Kotochigova, Svetlana

    2011-01-01

    The nature of the interaction between ultracold atoms with a large orbital and spin angular momentum has attracted considerable attention. It was suggested that such interactions can lead to the realization of exotic states of highly correlated matter. Here, we report on a theoretical study of the competing anisotropic dispersion, magnetic dipole-dipole, and electric quadrupole-quadrupole forces between two dysprosium atoms. Each dysprosium atom has an orbital angular momentum L=6 and magnetic moment $\\mu=10\\mu_B$. We show that the dispersion coefficients of the ground state adiabatic potentials lie between 1865 a.u. and 1890 a.u., creating a non-negligible anisotropy with a spread of 25 a.u. and that the electric quadrupole-quadrupole interaction is weak compared to the other interactions. We also find that for interatomic separations $R< 50\\,a_0$ both the anisotropic dispersion and magnetic dipole-dipole potential are larger than the atomic Zeeman splittings for external magnetic fields of order 10 G to ...

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

    Energy Technology Data Exchange (ETDEWEB)

    Kulka, M., E-mail: michal.kulka@put.poznan.pl; 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.

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

    Science.gov (United States)

    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.

  8. Corrosion behavior of boride layers evaluated by the EIS technique

    Energy Technology Data Exchange (ETDEWEB)

    Campos, I. [Instituto Politecnico Nacional. SEPI-ESIME U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F. 07738 (Mexico)], E-mail: icampos@ipn.mx; Palomar-Pardave, M. [Universidad Autonoma Metropolitana-Azcapotzalco, Materials Department, Avenue San Pablo 180 Col. Reynosa Tamaulipas, Mexico D.F. 02200 (Mexico); Amador, A. [Tecnologico de Monterrey, Campus Ciudad de Mexico, Calle del Puente 222 Col. Ejidos de Huipulco, Mexico D.F. 14380 (Mexico); VillaVelazquez, C. [Instituto Politecnico Nacional. SEPI-ESIME U.P. Adolfo Lopez Mateos, Zacatenco, Mexico D.F. 07738 (Mexico); Hadad, J. [Tecnologico de Monterrey, Campus Ciudad de Mexico, Calle del Puente 222 Col. Ejidos de Huipulco, Mexico D.F. 14380 (Mexico)

    2007-09-30

    The corrosion behavior of boride layers at the AISI 304 steel surface is evaluated in the present study. Electrochemical impedance spectroscopy (EIS) technique was used for the evaluation of the polarization resistance at the steel surface, with the aid of AUTOLAB potentiostat. Samples were treated with boron paste thickness of 4 and 5 mm, in the range of temperatures 1123 {<=} T {<=} 1273 K and exposed time of 4 and 6 h. The electrochemical technique employed 10 mV AC with a frequency scan range from 8 kHz to 3 mHz in deaerated 0.1 M NaCl solution. Nyquist diagrams show that the highest values of corrosion resistance are present in the samples borided at the temperature of 1273 K, with treatment time of 4 h and 4 mm of boron paste thickness. The values of corrosion resistance on borided steels are compared with the porosity exhibited in the layers.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Mikołajczak Daria

    2016-12-01

    Full Text Available 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.

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

    OpenAIRE

    Mikołajczak Daria; Kulka Michał; Makuch Natalia

    2016-01-01

    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 w...

  12. First search for double $\\beta$ decay of dysprosium

    CERN Document Server

    Belli, P; Cappella, F; Cerulli, R; Danevich, F A; d'Angelo, S; Di Vacri, M L; Incicchitti, A; Laubenstein, M; Nagorny, S S; Nisi, S; Tolmachev, A V; Tretyak, V I; Yavetskiy, R P

    2011-01-01

    A search for double $\\beta$ decay of dysprosium was realized for the first time with the help of an ultra low-background HP Ge $\\gamma$ detector. After 2512 h of data taking with a 322 g sample of dysprosium oxide limits on double beta processes in $^{156}$Dy and $^{158}$Dy have been established on the level of $T_{1/2}\\geq 10^{14}-10^{16}$ yr. Possible resonant double electron captures in $^{156}$Dy and $^{158}$Dy were restricted on a similar level. As a by-product of the experiment we have measured the radioactive contamination of the Dy$_2$O$_3$ sample and set limits on the $\\alpha$ decay of dysprosium isotopes to the excited levels of daughter nuclei as $T_{1/2}\\geq 10^{15} - 10^{17}$ yr.

  13. Subminiature eddy current transducers for studying boride coatings

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Makuch, N.; Kulka, M., E-mail: michal.kulka@put.poznan.pl

    2014-09-30

    Graphical abstract: - Highlights: • Two-stage gas boriding was proposed to produce the boride layer on Inconel 600-alloy. • The microstructure of diffusion zone consisted of compact borides zone and borides at grain boundaries. • The identification of nickel and chromium borides required the use of a special etching solution. • The diffusion along grain boundaries was indicated as a predominant mechanism of boron diffusion. • The increased hardness and improved wear resistance of gas-borided layer were obtained. - Abstract: 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 N{sub 2}–H{sub 2}–BCl{sub 3} atmosphere is proposed for the producing the boride layer on Inconel{sup ®}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.

  16. Neutron resonance parameters of dysprosium isotopes using neutron capture yields

    Energy Technology Data Exchange (ETDEWEB)

    Shin, S. G.; Kye, Y. U.; Cho, M. H. [POSTECH, Pohang (Korea, Republic of); Namkung, W. [Pohang Accelerator Laboratory, Pohang (Korea, Republic of); Kim, G. N. [Kyungpook National University, Daegu (Korea, Republic of); Lee, M. W.; Kang, Y. R. [Dongnam Inst. Of Radiological and Medical Science, Busan (Korea, Republic of)

    2015-10-15

    Dysprosium is used in the field of nuclear reactor system because it has a very large thermal neutron absorption cross-section. The dysprosium alloyed with special stainless steels is attractive for control in nuclear reactor because of the ability to absorb neutrons readily without swelling or contracting over time and its high melting point. Dysprosium is also one of fission products from the thermal fission of {sup 234}U, {sup 233}U, and {sup 239}Pu. The fission products are accumulated in the reactor core by the burn-up of the nuclear fuel and the poison effect is increased. Therefore, it is required to understand how Dysprosium as both a poison and an absorbing material in the control rod has an effect on the neutron population in a nuclear reactor system over all energy regions. Neutron Capture experiments on Dy isotopes were performed at the electron linear accelerator (LINAC) facility of the Rensselear Polytechnic Institute (RPI) in the neutron energy region from 10 eV to 1 keV. Resonance parameters were extracted by fitting the neutron capture data using the SAMMY multilevel R-matrix Bayesian code.

  17. Characterisation of Wear Resistant Boride Layers on a Tool Steel by Activity Controlled Pack Boronising

    DEFF Research Database (Denmark)

    Fernandes, Frederico Augusto Pires; Christiansen, Thomas Lundin; Somers, Marcel A. J.

    2015-01-01

    The present work addresses the production and characterisation of iron boride layers by pack boronising of a Vanadis 6 tool steel. The boride layers were produced at 900°C for 2h using different pack compositions in order to obtain a single-phase boride layer. The layers were characterized...... by electron microscopy, glow discharge optical emission spectroscopy, X-ray diffraction, Vickers hardness tests and wear testing with a pin-on-disc tribometer. It was found that the type of boride phases (FeB and/or Fe2B) present in the treated layer can be controlled by changing the boron activity...

  18. Growth kinetics of boride layers formed on 99.0% purity nickel

    Indian Academy of Sciences (India)

    I Gunes; K Keddam; R Chegroune; M Ozcatal

    2015-08-01

    The present study reports on the kinetics of borided Nickel 201 alloy. The thermochemical treatment of boronizing was carried out in a solid medium consisting of B4C and KBF4 powders mixture at 1123, 1173 and 1223 K for 2, 4 and 6 h, respectively. The boride layer was characterized by optical microscopy, X-ray diffraction technique and micro-Vickers hardness tester. X-ray diffraction analysis revealed the existence of NiB, Ni2B, Ni3B and Ni4B3 compounds at the surface of borided Nickel 201 alloy. The thickness of the boride layer increased with an increase in the boriding time and the temperature. The hardness of the nickel borides formed on the surface of the nickel substrate ranged from 1642 to 1854 HV0.05, whereas the Vickers hardness value of the untreated nickel was 185 HV0.05. The growth kinetics of boride layers forming on the borided Nickel 201 alloy was also analysed. The boron activation energy () was estimated as equal to 203.87 kJ mol−1 for the borided Nickel 201 alloy.

  19. Metal Borohydrides synthesized from metal borides and metal hydrides

    DEFF Research Database (Denmark)

    Sommer, Sanna

    2014-01-01

    and Ca(BH4)2, respectively [3,4]. An attempt to synthesize alkali and alkaline earth metal borohydrides from various borides by ball milling under high hydrogen pressure is presented here. MgB2, AlB2 and CaB6 have been milled with MHx (M = Li, Na, Mg, Ca) at p(H2) = 110 bar for 24 hours. All samples were...

  20. Interfacial phenomena in molten metals-refractory borides systems

    OpenAIRE

    Muolo, Maria Luigia; Fabbreschi, Matteo; Passerone, Alberto; Passerone, Daniele

    2006-01-01

    Non-oxide ceramics, such as carbides, nitrides and borides represent one of the fastest growing classes of new advanced materials. Among them, transition metals ceramic diborides, in particular Titanium, Zirconium and Hafnium diborides, are members of a family of materials with extremely high melting temperatures, high thermal and electrical conductivity, excellent thermal shock resistance, high hardness and chemical inertness. These materials -Ultra High Temperature Ceramics (UHTCs)- constit...

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

    Energy Technology Data Exchange (ETDEWEB)

    Vajo, John

    2016-09-22

    DOE continues to seek reversible solid-state hydrogen materials with hydrogen densities of ³11 wt% and ³80 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. For the first approach, possible pairs of ternary borides and mixed-metal borohydrides based on Mg with various first row transition metals were investigated both experimentally and theoretically. In particular, the Mg/Mn ternary boride and mixed-metal borohydride were found to be a suitable pair and

  2. Properties of Polydisperse Tin-doped Dysprosium and Indium Oxides

    Directory of Open Access Journals (Sweden)

    Malinovskaya Tatyana

    2017-01-01

    Full Text Available The results of investigations of the complex permittivity, diffuse-reflectance, and characteristics of crystal lattices of tin-doped indium and dysprosium oxides are presented. Using the methods of spectroscopy and X-ray diffraction analysis, it is shown that doping of indium oxide with tin results in a significant increase of the components of the indium oxide complex permittivity and an appearance of the plasma resonance in its diffuse-reflectance spectra. This indicates the appearance of charge carriers with the concentration of more than 1021 cm−3 in the materials. On the other hand, doping of the dysprosium oxide with the same amount of tin has no effect on its optical and electromagnetic properties.

  3. Effect of microstructure on the wear resistance of borided Fe-Cr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Dybkov, Vasyl I. [Institute of Problems of Materials Science, Kyiv (Ukraine)

    2013-07-15

    Two boride layers were found to form at the interface between reacting phases in the course of boriding of Fe-Cr alloys (10, 15, 25 and 30% Cr) and chromium steels (13 and 25% Cr) in the temperature range of 850-950 C and reaction times 3600-43200 s (1-12h). In the case of Fe-10%Cr and Fe-15%Cr alloys and 13% Cr steel, the outer boride layer bordering the boriding agent consists of the (Fe,Cr)B phase, whereas the inner boride layer adjacent to the solid substrate consists of the (Fe,Cr)2B phase. Each layer is thus a homogeneous phase (type I microstructure). In contrast, on the surface of Fe-25%Cr and Fe-30%Cr alloys and 25% Cr steel each of the two boride layers consists of two phases and has a peculiar network-platelet morphology. The outer boride layer comprises the (Fe,Cr)B and (Cr,Fe)B phases, while the inner consists of the (Fe,Cr){sub 2}B and (Cr,Fe){sub 2}B phases (type II microstructure). It is such boride layers that exhibit the highest wear resistance. (orig.)

  4. Evaluation of High Temperature Particle Erosion Resistance of Vanadium-Boride Coating

    Energy Technology Data Exchange (ETDEWEB)

    Lee, E. Y.; Kim, J. H.; Jeong, S. I. [Andong National University, Andong (Korea, Republic of); Lee, S. H.; Eum, G. W. [Corporate R and D Institute Doosan Heavy Industries and Construction Co., Changwon (Korea, Republic of)

    2015-04-15

    The components in ultra super critical (USC) steam turbine, which is under development for high efficient power generation, are encountering harsher solid particle erosion by iron oxide scales than ones in the existing steam turbines. Therefore, the currently used boride coating will not be able to hold effective protection from particle erosion in USC system and should be replaced by new particle erosion resistant coatings. One of the best protective coatings developed for USC steam turbine parts was found to be vanadium-boride (V-boride) coating which has a hardness of about 3000 HV, much higher than that of boride, 1600∼2000 HV. In order to evaluate particle erosion resistance of the various coatings such as V-boride, boride and Cr-carbide coatings at high temperature, particle erosion test equipment were designed and manufactured. In addition, erosion particle velocity was simulated using FLUENT software based on semi-implicity method for pressure linked equations revised (SIMPLER). Based on experimental results of this work, the vanadium-boride coating was found to be superior to others and to be a candidate coating to replace the boride coating.

  5. Dysprosium titanate as an absorber material for control rods

    Science.gov (United States)

    Risovany, V. D.; Varlashova, E. E.; Suslov, D. N.

    2000-09-01

    Disprosium titanate is an attractive control rod material for the thermal neutron reactors. Its main advantages are: insignificant swelling, no out-gassing under neutron irradiation, rather high neutron efficiency, a high melting point (˜1870°C), non-interaction with the cladding at temperatures above 1000°C, simple fabrication and easily reprocessed non-radioactive waste. It can be used in control rods as pellets and powder. The disprosium titanate control rods have worked off in the MIR reactor for 17 years, in VVER-1000 - for 4 years without any operating problems. After post-irradiation examinations this type of control rod having high lifetime was recommended for the VVER and RBMK. The paper presents the examination results of absorber element dummies containing dysprosium titanate, irradiated in the SM reactor to the neutron fluence of 3.4×10 22 cm -2 ( E>0.1 MeV) and, also, the data on structure, thermal-physical properties of dysprosium titanate, efficiency of dysprosium titanate control rods.

  6. Effect of Fe2B boride orientation on abrasion wear resistance of Fe-B cast alloy

    Directory of Open Access Journals (Sweden)

    Da-wei Yi

    2017-07-01

    Full Text Available The microstructures and abrasion wear resistance of directional solidification Fe-B alloy have been investigated using optical microscopy, X-ray diffraction, scanning electron microscopy and laser scanning microscopy. The results show that the microstructure of as-cast Fe-B alloy consists of ferrite, pearlite and eutectic boride. After heat treatment, the microstructure is composed of boride and martensite. The plane which is perpendicular to the boride growth direction possesses the highest hardness. In two-body abrasive wear tests, the silicon carbide abrasive can cut the boride and martensite matrix synchronously, and the wear mechanism is micro cutting mechanism. The worn surface roughness and the wear weight loss both increase with the increasing contact load. Moreover, when the boride growth direction is perpendicular to the worn surface, the highest hardness plane of the boride can effectively oppose abrasion, and the martensite matrix can surround and support borides perfectly.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Selva Kumar, M., E-mail: sel_mcet@yahoo.co.in [Department of Mechanical Engineering, Dr. Mahalingam College of Engineering and Technology, Pollachi-642003 (India); Chandrasekar, P.; Chandramohan, P. [School of Engineering, Professional Group of Institutions, Coimbatore-641662 (India); Mohanraj, M. [Department of Mechanical Engineering, Info Institute of Engineering, Coimbatore-641107 (India)

    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.

  9. Electron momentum distribution and electronic response of ceramic borides

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2016-01-14

    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.

  11. Electron momentum distribution and electronic response of ceramic borides

    Energy Technology Data Exchange (ETDEWEB)

    Heda, N.L. [Department of Pure and Applied Physics, University of Kota, Kota 324005 (India); Meena, B.S.; Mund, H.S. [Department of Physics, Mohanlal Sukhadia University, Udaipur 313001 (India); Sahariya, Jagrati [Department of Physics, Manipal University, Jaipur 303007 (India); Kumar, Kishor [Department of Physics, Mohanlal Sukhadia University, Udaipur 313001 (India); Ahuja, B.L., E-mail: blahuja@yahoo.com [Department of Physics, Mohanlal Sukhadia University, Udaipur 313001 (India)

    2017-03-15

    Isotropic Compton profiles of transition metal based ceramics TaB and VB have been measured using {sup 137}Cs (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.

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

    Science.gov (United States)

    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%).

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

    Science.gov (United States)

    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.

  14. Influence of alloy ingredients on mechanical properties of ternary boride hard alloy clad materials

    Institute of Scientific and Technical Information of China (English)

    LIU Fu-tian; SONG Shi-xue; YANG Jun-ru; HUANG Wei-ling; HUANG Chuan-zhen; CHENG Xin; LI Zhao-qian

    2004-01-01

    Using Mo, B-Fe alloy and Fe powders as raw materials, and adding C, Cr and Ni ingredients, respectively, or C, Cr and Ni mixed powders, ternary boride hard alloy clad materials was prepared on Q235 steel substrate by means of in-situ reaction and vacuum liquid phase sintering technology. The influence of alloy ingredients on the mechanical properties of ternary boride hard alloy clad materials was investigated. The results indicate that a mixture of 0.8% C, 5% Cr and 2% Ni ingredients gives a ternary boride hard alloy clad material with optimal mechanical properties, such as high transverse rupture strength, high hardness and good wear resistance.

  15. Dysprosium electrodeposition from a hexaalkylguanidinium-based ionic liquid

    Science.gov (United States)

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

    2016-07-01

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

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

    Science.gov (United States)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Kulka, M., E-mail: michal.kulka@put.poznan.pl; 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.

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

    Science.gov (United States)

    2015-02-19

    to their oxide counterparts. In general, borides of rare-earth and d-transitional metals have outstanding refractory properties with high hardness...AFRL-AFOSR-UK-TR-2015-0021 The nature of the microstructure and interface boundary formation in directionally solidified ceramic ...microstructure and interface boundary formation in directionally solidified ceramic boride composites 5a. CONTRACT NUMBER STCU P-512 5b. GRANT NUMBER

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

    Science.gov (United States)

    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.

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

    OpenAIRE

    Galevskiy, G. V.; Rudneva, V. V.; Galevskiy, S. G.; Ilyashchenko, Dmitry Pavlovich; Karthev, Dmitry Sergeevich

    2016-01-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Vajo, John J. [HRL Laboratories, LLC, Malibu, CA (United States)

    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.

  2. Characterization and wear performance of boride phases over tool steel substrates

    Directory of Open Access Journals (Sweden)

    Edgar E Vera Cárdenas

    2016-02-01

    Full Text Available This research work was conducted to characterize boride phases, obtained from the powder-pack process, on AISI H13 and D2 steel substrates, and investigate their tribological behavior. The boriding was developed at a temperature of 1273 K with an exposure time of 8 h. X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were conducted on the borided material to characterize the presence of the FeB, Fe2B, and CrB phases and the distribution of heavy elements on the surface of the substrates. The adherence of the boride layers was evaluated, in a qualitative form, through the Daimler-Benz Rockwell-C indentation technique. Sliding wear tests were then performed using a reciprocating wear test machine. All tests were conducted in dry conditions at room temperature. A frequency of 10 Hz and 15-mm sliding distance were used. The applied Hertzian pressure was 2.01 GPa. Scanning electron microscopy was used to observe and analyze the wear mechanisms. Additionally, the variation of the friction coefficient versus the number of cycles was obtained. Experimental results showed that the characteristic wear mechanism for the borided surface was plastic deformation and mild abrasive wear; for unborided substrates, cracking and spalling were observed.

  3. THE INTERFACE OF TERNARY-BORIDE-BASED HARD CLADDING MATERIAL

    Institute of Scientific and Technical Information of China (English)

    Y.G. Wang; Z.Q. Li; D. Zhang

    2004-01-01

    The interfacial microstructure of ternary-boride-based hard cladding material (YF2) has been studied using scanning electron microanalyser (SEM), X-ray diffraction (XRD) and energy disperse spectroscopy (EDS). Results show that there are chemical reactions and elements diffusion in the interfacial zone, which make the interface bonding well and bonding strength ideal at the interface. The results gotten by studying of crack produced by Vickers indentation technique in the interfacial zone show that it is difficult to produce crack in the interface, the crack length in the cladding layer is longer than that to the interface, the crack which propagate to the interface stops at the interface rather than propagates along the interface. This suggests negligible residual stresses have developed because of thermal expansion mismatch. The bonding strength of the interface is 550MPa, which has been gotten by cutting test. The result gotten by analyzing the fracture surface shows that the fracture occurs at the side of cladding layer, which confirms that the bonding strength at the interface is higher than that in the cladding layer.

  4. A kinetic model for estimating the boron activation energies in the FeB and Fe{sub 2}B layers during the gas-boriding of Armco iron: Effect of boride incubation times

    Energy Technology Data Exchange (ETDEWEB)

    Keddam, M. [Laboratoire de Technologie des Matériaux, Département de Sciences des Matériaux, Faculté de Génie Mécanique et Génie des Procédés, USTHB, B.P N°32, 16111, El-Alia, Bab-Ezzouar, Algiers (Algeria); Kulka, M., E-mail: michal.kulka@put.poznan.pl [Poznan University of Technology, Institute of Materials Science and Engineering, Pl. M.Sklodowskiej-Curie 5, 60-965 Poznan (Poland); Makuch, N.; Pertek, A. [Poznan University of Technology, Institute of Materials Science and Engineering, Pl. M.Sklodowskiej-Curie 5, 60-965 Poznan (Poland); Małdziński, L. [Poznan University of Technology, Institute of Machines and Motor Vehicles, Piotrowo Street 3, 60-965 Poznan (Poland)

    2014-04-01

    Graphical abstract: - Highlights: • The mass balance equations were formulated for the FeB and Fe{sub 2}B layers grown on Fe Armco by gas-boriding. • The effect of boride incubation times was incorporated in the present model. • The boride incubation time was shorter for FeB phase. • The calculated boron activation energies in FeB and Fe{sub 2}B were respectively close to 78.03 and 120.65 kJ mol{sup −1}. • The lower activation energy in FeB phase was characteristic of gas-boriding. - Abstract: The present work deals with a simulation of the growth kinetics of boride layers grown on Armco iron substrate. The formed boride layers (FeB + Fe{sub 2}B) 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/Fe{sub 2}B) and (Fe{sub 2}B/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 Fe{sub 2}B and the experimental parabolic growth constants) are needed to determine the boron activation energies in the FeB and Fe{sub 2}B 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.

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

    Science.gov (United States)

    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.

  6. Hard Surface Layers by Pack Boriding and Gaseous Thermo-Reactive Deposition and Diffusion Treatments

    DEFF Research Database (Denmark)

    Christiansen, Thomas Lundin; Bottoli, Federico; Dahl, Kristian Vinter

    2017-01-01

    subjected to TRD (chromizing and titanizing) and boriding treatments. For the steels with low carbon content, chromizing results in surface alloying with chromium, i.e., formation of a (soft) “stainless” surface zone. Steels containing higher levels of carbon form chromium carbide (viz. Cr23C6, Cr7C3......) layers with hardnesses up to 1800 HV. Titanizing of ARNE tool steel results in a surface layer consisting of TiC with a hardness of approximately 4000 HV. Duplex treatments, where boriding is combined with subsequent (TRD) titanizing, result in formation of hard TiB2 on top of a thick layer of Fe...

  7. FORMATION OF HIGHLY RESISTANT CARBIDE AND BORIDE COATINGS BY A TWO-STAGE DEPOSITION METHOD

    Directory of Open Access Journals (Sweden)

    W. I. Sawich

    2011-01-01

    Full Text Available A study was made of the aspects of forming highly resistant coatings in the surface zone of tool steels and solid carbide inserts by a two-stage method. at the first stage of the method, pure Ta or Nb coatings were electrodeposited on samples of tool steel and solid carbide insert in a molten salt bath containing Ta and Nb fluorides. at the second stage, the electrodeposited coating of Ta (Nb was subjected to carburizing or boriding to form carbide (TaC, NbC or boride (TaB, NbB cladding layers.

  8. Dysprosium detector for neutron dosimetry in external beam radiotherapy

    Science.gov (United States)

    Ostinelli, A.; Berlusconi, C.; Conti, V.; Duchini, M.; Gelosa, S.; Guallini, F.; Vallazza, E.; Prest, M.

    2014-09-01

    Radiotherapy treatments with high-energy (>8 MeV) photon beams are a standard procedure in clinical practice, given the skin and near-target volumes sparing effect, the accurate penetration and the uniform spatial dose distribution. On the other hand, despite these advantages, neutrons may be produced via the photo-nuclear (γ,n) reactions of the high-energy photons with the high-Z materials in the accelerator head, in the treatment room and in the patient, resulting in an unwanted dose contribution which is of concern, given its potential to induce secondary cancers, and which has to be monitored. This work presents the design and the test of a portable Dysprosium dosimeter to be used during clinical treatments to estimate the "in vivo" dose to the patient. The dosimeter has been characterized and validated with tissue-equivalent phantom studies with a Varian Clinical iX 18 MV photon beam, before using it with a group of patients treated at the S. Anna Hospital in Como. The working principle of the dosimeter together with the readout chain and the results in terms of delivered dose are presented.

  9. Dysprosium detector for neutron dosimetry in external beam radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Ostinelli, A.; Berlusconi, C.; Conti, V.; Duchini, M.; Gelosa, S. [Medical Physics - Sant' Anna Hospital, Como (Italy); Guallini, F. [EL.SE s.r.l. (Italy); Vallazza, E. [INFN, Trieste (Italy); Prest, M. [University of Insubria, Como (Italy)

    2014-09-21

    Radiotherapy treatments with high-energy (>8MeV) photon beams are a standard procedure in clinical practice, given the skin and near-target volumes sparing effect, the accurate penetration and the uniform spatial dose distribution. On the other hand, despite these advantages, neutrons may be produced via the photo-nuclear (γ,n) reactions of the high-energy photons with the high-Z materials in the accelerator head, in the treatment room and in the patient, resulting in an unwanted dose contribution which is of concern, given its potential to induce secondary cancers, and which has to be monitored. This work presents the design and the test of a portable Dysprosium dosimeter to be used during clinical treatments to estimate the “in vivo” dose to the patient. The dosimeter has been characterized and validated with tissue-equivalent phantom studies with a Varian Clinical iX 18 MV photon beam, before using it with a group of patients treated at the S. Anna Hospital in Como. The working principle of the dosimeter together with the readout chain and the results in terms of delivered dose are presented.

  10. Low Field Magnetic and Thermal Hysteresis in Antiferromagnetic Dysprosium

    Directory of Open Access Journals (Sweden)

    Iuliia Liubimova

    2017-06-01

    Full Text Available Magnetic and thermal hysteresis (difference in magnetic properties on cooling and heating have been studied in polycrystalline Dy (dysprosium between 80 and 250 K using measurements of the reversible Villari effect and alternating current (AC susceptibility. We argue that measurement of the reversible Villari effect in the antiferromagnetic phase is a more sensitive method to detect magnetic hysteresis than the registration of conventional B(H loops. We found that the Villari point, recently reported in the antiferromagnetic phase of Dy at 166 K, controls the essential features of magnetic hysteresis and AC susceptibility on heating from the ferromagnetic state: (i thermal hysteresis in AC susceptibility and in the reversible Villari effect disappears abruptly at the temperature of the Villari point; (ii the imaginary part of AC susceptibility is strongly frequency dependent, but only up to the temperature of the Villari point; (iii the imaginary part of the susceptibility drops sharply also at the Villari point. We attribute these effects observed at the Villari point to the disappearance of the residual ferromagnetic phase. The strong influence of the Villari point on several magnetic properties allows this temperature to be ranked almost as important as the Curie and Néel temperatures in Dy and likely also for other rare earth elements and their alloys.

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

    OpenAIRE

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

    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 compariso...

  12. A Low-Symmetry Dysprosium Metallocene Single-Molecule Magnet with a High Anisotropy Barrier.

    Science.gov (United States)

    Pugh, Thomas; Chilton, Nicholas F; Layfield, Richard A

    2016-09-05

    The single-molecule magnet (SMM) properties of the isocarbonyl-ligated dysprosium metallocene [Cp*2 Dy{μ-(OC)2 FeCp}]2 (1Dy ), which contains a rhombus-shaped Dy2 Fe2 core, are described. Combining a strong axial [Cp*](-) ligand field with a weak equatorial field consisting of the isocarbonyl ligands leads to an anisotropy barrier of 662 cm(-1) in zero applied field. The dominant thermal relaxation pathways in 1Dy involves at least the fourth-excited Kramers doublet, thus demonstrating that prominent SMM behavior can be observed for dysprosium in low-symmetry environments.

  13. Electrosynthesis of tantalum borides in oxygen-free and oxygen-containing fluoride melts

    DEFF Research Database (Denmark)

    Polyakova, L.P.; Polyakov, E.G.; Makarova, O.V.;

    2001-01-01

    Results of electrosynthesis of tantalum borides in fluoride and oxyfluoride melts are compared. It is shown that the single-phase X-ray-amorphous micro-layered coatings form only in the latter case. Linear and square-wave voltammetry, complemented by X-ray diffraction analysis, IR spectroscopy...

  14. Nickel boride: An improved desulphurizing agent for sulphur-rich geomacromolecules in polar and asphaltene fractions

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Schouten, S.; Pavlovic, D.; Leeuw, J.W. de

    1993-01-01

    Nickel boride, a novel desulphurizing agent, was investigated for the desulphurization of sulphur-rich geomacromolecules in polar and asphaltene fractions. It was found to be as effective as the conventional desulphurizing agent, Raney nickel, for sulphur-rich geomacromolecules in polar fractions, b

  15. Electrosynthesis of tantalum borides in oxygen-free and oxygen-containing fluoride melts

    DEFF Research Database (Denmark)

    Polyakova, L.P.; Polyakov, E.G.; Makarova, O.V.

    2001-01-01

    Results of electrosynthesis of tantalum borides in fluoride and oxyfluoride melts are compared. It is shown that the single-phase X-ray-amorphous micro-layered coatings form only in the latter case. Linear and square-wave voltammetry, complemented by X-ray diffraction analysis, IR spectroscopy...

  16. Structure of surface layers produced by non-vacuum electron beam boriding

    Energy Technology Data Exchange (ETDEWEB)

    Bataev, I.A., E-mail: ivanbataev@ngs.ru [Novosibirsk State Technical University, K. Marks 20, 630092 Novosibirsk (Russian Federation); Bataev, A.A., E-mail: bataev@adm.nstu.ru [Novosibirsk State Technical University, K. Marks 20, 630092 Novosibirsk (Russian Federation); Golkovski, M.G., E-mail: M.G.Golkovski@inp.nsk.su [Budker Institute of Nuclear Physics SB RAS, Lavrentieva prospect 11, 630090 Novosibirsk (Russian Federation); Krivizhenko, D.S., E-mail: dinylkaa@yandex.ru [Novosibirsk State Technical University, K. Marks 20, 630092 Novosibirsk (Russian Federation); Losinskaya, A.A., E-mail: anna.losinskaya@mail.ru [Novosibirsk State Technical University, K. Marks 20, 630092 Novosibirsk (Russian Federation); Lenivtseva, O.G., E-mail: lenivtseva_olga@mail.ru [Novosibirsk State Technical University, K. Marks 20, 630092 Novosibirsk (Russian Federation)

    2013-11-01

    The structure and mechanical properties of boronized layers produced on low carbon steel substrates by non-vacuum electron-beam cladding were studied. This process provides high performance and high thickness of coatings and can be used to process large workpieces. In this study, we investigated coatings obtained by one, two or three passes of the electron beam. The thickness of the coatings varied from 0.6 to 1.0 mm, and the maximum hardness achieved was 21 GPa. Structural analysis revealed the oriented growth of eutectic colonies near the primary crystals of iron borides, which was explained by the commonality of the boride phases in the primary Fe{sub 2}B and eutectic Fe{sub 2}B. The eutectic colonies formed during electron-beam cladding consisted of a continuous framework of borides crystals and segregations of α-Fe in the form of oriented fibers. Coatings produced by electron-beam cladding had higher contact-fatigue endurance than those produced by pack boriding.

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

    Energy Technology Data Exchange (ETDEWEB)

    None

    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.

  18. Malonate complexes of dysprosium: synthesis, characterization and application for LI-MOCVD of dysprosium containing thin films.

    Science.gov (United States)

    Milanov, Andrian P; Seidel, Rüdiger W; Barreca, Davide; Gasparotto, Alberto; Winter, Manuela; Feydt, Jürgen; Irsen, Stephan; Becker, Hans-Werner; Devi, Anjana

    2011-01-07

    A series of malonate complexes of dysprosium were synthesized as potential metalorganic precursors for Dy containing oxide thin films using chemical vapor deposition (CVD) related techniques. The steric bulkiness of the dialkylmalonato ligand employed was systematically varied and its influence on the resulting structural and physico-chemical properties that is relevant for MOCVD was studied. Single crystal X-ray diffraction analysis revealed that the five homoleptic tris-malonato Dy complexes (1-5) are dimers with distorted square-face bicapped trigonal-prismatic geometry and a coordination number of eight. In an attempt to decrease the nuclearity and increase the solubility of the complexes in various solvents, the focus was to react these dimeric complexes with Lewis bases such as 2,2'-biypridyl and pyridine (6-9). This resulted in monomeric tris-malonato mono Lewis base adduct complexes with improved thermal properties. Finally considering the ease of synthesis, the monomeric nature and promising thermal characteristics, the silymalonate adduct complex [Dy(dsml)(3)bipy] (8) was selected as single source precursor for growing DySi(x)O(y) thin films by liquid injection metalorganic chemical vapor deposition (LI-MOCVD) process. The as-deposited films were analyzed for their morphology and composition by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, Rutherford backscattering (RBS) analysis and X-ray photoelectron spectroscopy.

  19. Exploration of dysprosium: the most critical element for Japan

    Science.gov (United States)

    Watanabe, Y.

    2012-04-01

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

  20. Long afterglow of trivalent dysprosium doped strontium aluminate

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yuan Ming, E-mail: dongshanisland@126.com [School of Mathematics and Physics, Changzhou University, Jiangsu 213164 (China); Ma, Qing-lan [School of Mathematics and Physics, Changzhou University, Jiangsu 213164 (China); School of Electronics and Information, Nantong University, Jiangsu 226019 (China)

    2015-04-15

    Trivalent dysprosium doped strontium aluminate (SrA1{sub 2}O{sub 4}:Dy{sup 3+}) was synthesized via the sol–gel combustion method to realize green afterglow in the absence of Eu{sup 2+} luminescent centers. The morphology, crystal structure, photoluminescence and long afterglow of the SrAl{sub 2}O{sub 4}:Dy{sup 3+} were characterized with scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy and photoluminescence spectroscopy, respectively. The bluish-green photoluminescence of SrAl{sub 2}O{sub 4}:Dy{sup 3+} consists of a broad emission band centered at about 520 nm and two characteristic emissions of Dy{sup 3+} ions centered at 480 and 575 nm, respectively. The green afterglow of SrAl{sub 2}O{sub 4}:Dy{sup 3+} is a broad emission band centered at around 520 nm, and the lifetime extracted from afterglow decay is found to be 53 s. The mechanism on the green afterglow from SrAl{sub 2}O{sub 4}:Dy{sup 3+} is discussed in terms of the possible defect levels in the host. - Highlights: • Broad band long-lasting afterglow is observed in SrAl{sub 2}O{sub 4}:Dy{sup 3+} phosphors. • Characteristic emissions of Dy{sup 3+} ions are superimposed on the broad PL of phosphors. • Dy{sup 3+} ions can also act as luminescent centers in addition to electron traps. • A mechanism on long afterglow of SrAl{sub 2}O{sub 4}:Dy{sup 3+} is proposed without Eu{sup 2+} activator.

  1. Low temperature spin reorientation in dysprosium iron garnet

    Energy Technology Data Exchange (ETDEWEB)

    Lahoubi, M; Younsi, W; Soltani, M L [Department of Physics, Badji-Mokhtar University, BP-12 Annaba, 23000 (Algeria); Voiron, J; Schmitt, D, E-mail: mlahoubi@gmail.co [Louis Neel Laboratory, CNRS-UJF, BP-166, 38042 Grenoble Cedex 9 (France)

    2009-03-01

    The spin reorientation (SR) phase transition in dysprosium iron garnet (Dy{sub 3}Fe{sub 5}O{sub 12} or DyIG) have been studied by specific heat C{sub p}(T) and high field magnetisation measurements M{sub T}(H) and M{sub H}(T) on single crystals at low temperature. A first order SR is observed with a sharp jump at T{sub SR} = 14.5+-0.5 K in the C{sub p}(T) curve which corresponds to a spontaneous change from the high temperature (HT) easy direction (111) to an (uuw) angular low temperature (LT) phases. Above T{sub SR}, the magnetic structure is described by the irreducible representation (IR) A{sub 2g} of the rhombohedral space group R 3 c. Below T{sub SR}, the magnetic structure changes in the monoclinic the space group C2/c with the IR A{sub g}. When the field H is kept aligned along the hard symmetry directions (100) and (110), we obtain respectively the variation of the angular positions theta(T) and theta'(T) from the total spontaneous magnetisation down to 1.5 K (theta = 39.23 deg. and theta' = 30.14 deg.) and the results are in good agreement with the previous observations in low fields. When the sample is allowed to rotate freely on itself, the critical field H{sub c}(T) between the HT(111) and the LT(uuw) angular phases permits us to precise the transition line up to 15 T and 40 K between the so called canted field induced (FI) and the associated collinear magnetic phases. The experimental magnetic phase diagram (MPD) is precisely determined in the (H{sub c}-T) plane and the domains of the existence and the stability of the two magnetic phases are specified.

  2. Anisotropic magnetic properties of dysprosium iron garnet (DyIG)

    Energy Technology Data Exchange (ETDEWEB)

    Lahoubi, M; Younsi, W; Soltani, M-L [Department of Physics, Badji-Mokhtar University, BP 12 - 23000 Annaba (Algeria); Ouladdiaf, B, E-mail: mlahoubi@gmail.co [Institut Laue Langevin, BP 156 - 38042 Grenoble Cedex 9 (France)

    2010-01-01

    The magnetic properties of dysprosium iron garnet (DyIG) have been studied by performing high resolution powder neutron diffraction experiments and high dc fields magnetizations on single crystals. Among all the reflections (hkl) indexed in the nuclear cubic space group (CSG) Ia 3-bar d with h+k+l=2n and k=[000], the superstructure lines (hkl)* forbidden by the symmetry (222)* and (622)* are not observed in the patterns at all temperatures. The pattern at 130 K is well interpreted within the magnetic modes F belonging to the irreducible representation (IR) T{sub 1g} of the CSG and identified to the room temperature ferrimagnetic Neel model. The high magnetic field behavior of the spontaneous collinear magnetic structure (MS) along the easy axis (EA) <111> is isotropic. Below 130 K, the patterns exhibit additional magnetic superstructure lines. They are associated to the appearance of the spontaneous non collinear MS which is described in the subgroup of the CSG, R 3-bar c within the IR A{sub 2g}. A strong magnetization anisotropy (MA) is observed at 1.5 K in the low symmetry phases were the spin reorientation transition (SR) occur at T{sub RS}=14.5 K. The onset of MA is detected below two characteristic temperatures, Ta{sub 1}=125 K and Ta{sub 2}=75 K respectively to the hard axis (HA) <100> and <110>. Symmetry arguments are used in the framework of the theory of representation analysis (RA) applied to the subgroup of R 3-bar c, C2/c within the IR A{sub g}. It seems that this MA results essentially from the difference between the spontaneous non collinear MS and the field induced (FI) configurations. All results are discussed with previous neutrons studies.

  3. Dysprosium-containing layered double hydroxides nanoparticles intercalated with biologically active species as an approach for theranostic systems

    KAUST Repository

    Arratia-Quijada, Jenny

    2015-10-23

    A layered double hydroxide structure including dysprosium cations was prepared by co-precipitation. The nanoparticles showed a linear relationship with the reciprocal relaxation spin-lattice (T1) time of water protons which is reflected as contrast in aqueous suspensions analyzed by magnetic resonance imaging. The interlayer space of dysprosium containing LDH was successfully intercalated with folate, ibuprofen and gallate ions, which are key molecules for recognition of some cancer cells and treatment of diseases. The paramagnetic property of the dysprosium-containing LDH detected in this work beside the ability to transport drugs open up the opportunity to design theranostic materials in a single crystal phase with nanometric dimensions.

  4. Signs of superconductivity at 110 K on inclusions of TiB sub k boride phases into titanium matrix

    CERN Document Server

    Volkov, V V; Berzverkhij, P P; Martynets, V G; Matizen, E V

    2002-01-01

    Verification of theoretical forecasts on the possibility of the high-temperature superconductivity of the high-temperature superconductivity (HTSC) in the TiB sub k titanium borides is accomplished. It is established that the jump-like change in the temperature dependence of the electric resistance R(T) at 110 K takes place on the titanium samples, the surfaces whereof are coated with the borides diffusion layers of the TiB sub k variable in-depth composition. This proves the presence of the borides diffusion layers are applied onto the metallic titanium by means of treating its surface with the B sub 2 H sub 6 + H sub 2 gases mixture at the temperature of 610-700 deg C with the subsequent annealing in vacuum. The boride layers composition is studied through the mass-spectrometry method

  5. 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

    Science.gov (United States)

    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.

  6. Effects of Dysprosium Oxide Doping on Microstructure and Properties of Barium Titanate Ceramic

    Institute of Scientific and Technical Information of China (English)

    Pu Yongping; Ren Huijun; Chen Wei; Chen Shoutian

    2005-01-01

    Different amounts of dysprosium oxide were incorporated into barium titanate powders synthesized by hydrothermal method. Relations of substitution behaviors and lattice parameters with solid-solubility were studied. Furthermore, the influences of dysprosium oxide doping fraction on grain size and dielectric properties of barium titanate ceramic, including dielectric constant and breakdown electric field strength, were investigated via scanning electron microscope, X-ray diffraction and electric property tester. The results show that dysprosium oxide can restrain abnormal grain growth during sintering and that fine-grained and high density of barium titanate ceramic can result in excellent dielectric properties. As mass fraction of dysprosium oxide is 0.6%, the lattice parameters of grain increase to the maximum because of the lowest vacancy concentration. The electric property parameters are cited as following: dielectric constant (25 ℃) reaches 4100, the change in relative dielectric constant with temperature is -10% to 10% within the range of -15~100 ℃, breakdown electric field strength (alternating current) achieves 3.2 kV·mm-1, which can be used in manufacturing high voltage ceramic capacitors.

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

    Science.gov (United States)

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

    2011-09-14

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

  8. In situ characterization of the nitridation of dysprosium during mechanochemical processing

    Energy Technology Data Exchange (ETDEWEB)

    Jaques, Brian J.; Osterberg, Daniel D.; Alanko, Gordon A.; Tamrakar, Sumit; Smith, Cole R.; Hurley, Michael F.; Butt, Darryl P., E-mail: DarrylButt@BoiseState.edu

    2015-01-15

    Highlights: • A nitridation reaction in a high energy planetary ball mill was monitored in situ. • Dysprosium mononitride was synthesized from Dy at low temperatures in short times. • Ideal gas law and in situ temperature and pressure used to assess reaction extent. • It is proposed that reaction rate is proportional to the creation of new surface. - Abstract: Processing of advanced nitride ceramics traditionally requires long durations at high temperatures and, in some cases, in hazardous atmospheres. In this study, dysprosium mononitride (DyN) was rapidly formed from elemental dysprosium in a closed system at ambient temperatures. An experimental procedure was developed to quantify the progress of the nitridation reaction during mechanochemical processing in a high energy planetary ball mill (HEBM) as a function of milling time and intensity using in situ temperature and pressure measurements, SEM, XRD, and particle size analysis. No intermediate phases were formed. It was found that the creation of fresh dysprosium surfaces dictates the rate of the nitridation reaction, which is a function of milling intensity and the number of milling media. These results show clearly that high purity nitrides can be synthesized with short processing times at low temperatures in a closed system requiring a relatively small processing footprint.

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

    Science.gov (United States)

    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.

  10. Dysprosium complexes with the tetraphenylporphyrin macrocyclic ligand; Complejos de disprosio con el ligante macrociclico tetrafenilporfirina

    Energy Technology Data Exchange (ETDEWEB)

    Martinez M, V.; Padilla, J.; Ramirez, F.M

    1992-04-15

    In this report, the results obtained on the synthesis, characterization and study of the chemical behavior of dysprosium complex with the acetylacetone chelating agent (Hacac) and the tetraphenylporphyrin macrocyclic ligand (H{sub 2}TFP) are given. Based on the literature but according to our necessities and interest, the appropriate methodology settled down from the synthesis of prime matters until the obtaining and characterization of the products. The acetyl acetonate complex was obtained of mono hydrated dysprosium [Dy(acac){sub 3}. H{sub 2}0] and trihydrated [Dy(acac){sub 3} .3 H{sub 2}0], the mono tetra phenyl porphyrinate [Dy(TFP)(acac). 2 ac] the double sandwich of the dysprosium porphyrinate [Dy(TFP){sub 2}] and the triple sandwich of the dysprosium porphyrinate [Dy(TFP){sub 3}. 2 TCB] (TCB = trichlorobenzene). Its were characterized by their melting points, solubility, IR, UV, TGA and DTA both first and besides the techniques already mentioned for NMR'H, RPE and Magnetic susceptibility the three last complexes. From the spectroscopic point of view, IR and RPE its suggested the existence of a complex of inverse mixed valence [Dy(TFP){sup 2-} (TFP) {sup 1-}] for the Dy(TFP){sub 2} as a result of the existence of the free radical (TFP' {sup 1-} and that it was not in none of the other porphyrin compounds. In the NMR'H spectra of the compounds were not observed signals in the region from 0 to 10 ppm that which shows that the dysprosium complexes in special those of the porphyrin type are highly paramagnetic and its could be used as displacement reagents, creators of images and contrast agents of great utility in these days in studies of NMR, technique today by today used in medical diagnoses. (Author)

  11. Synthesis, structural characterization and in vitro testing of dysprosium containing silica particles as potential MRI contrast enhancing agents

    Science.gov (United States)

    Chiriac, L. B.; Trandafir, D. L.; Turcu, R. V. F.; Todea, M.; Simon, S.

    2016-11-01

    The work is focused on synthesis and structural characterization of novel dysprosium-doped silica particles which could be considered as MRI contrast agents. Sol-gel derived silica rich particles obtained via freeze-drying and spray-drying processing methods were structurally characterized by XRD, 29Si MAS-NMR and XPS methods. The occurrence of dysprosium on the outermost layer of dysprosium containing silica particles was investigated by XPS analysis. The MRI contrast agent characteristics have been tested using RARE-T1 and RARE-T2 protocols. The contrast of MRI images delivered by the investigated samples was correlated with their local structure. Dysprosium disposal on microparticles with surface structure characterised by decreased connectivity of the silicate network units favours dark T2-weighted MRI contrast properties.

  12. Dysprosium-containing layered double hydroxides nanoparticles intercalated with biologically active species as an approach for theranostic systems

    Energy Technology Data Exchange (ETDEWEB)

    Arratia-Quijada, Jenny [Departamento de Ciencias de la Salud, Centro Universitario Tonalá, Universidad de Guadalajara, Av. Nuevo Periférico No. 555, C.P. 48525, Tonalá, Jalisco (Mexico); Sánchez Jiménez, Cecilia [Departamento de Química, Universidad de Guadalajara, Boulevard Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico); Gurinov, Andrey [Research Resources Center for Magnetic Resonance, St. Petersburg State University, Universitetskiy pr. 26, 198504 St. Petersburg (Russian Federation); NMR Core Lab, King Abdullah University of Science and Technology, Thuwal 23955-6900 (Saudi Arabia); Pérez Centeno, Armando; Ceja Andrade, Israel [Departamento de Física, Universidad de Guadalajara, Boulevard Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico); Carbajal Arízaga, Gregorio Guadalupe, E-mail: gregoriocarbajal@yahoo.com.mx [Departamento de Química, Universidad de Guadalajara, Boulevard Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico)

    2016-01-15

    Graphical abstract: - Highlights: • LDH structure including dysprosium was prepared by co-precipitation. • LDH was capable to produce contrast in the T1 mode of MRI. • LDH were intercalated with folate, ibuprofen and gallate ions. - Abstract: A layered double hydroxide structure including dysprosium cations was prepared by co-precipitation. The nanoparticles showed a linear relationship with the reciprocal relaxation spin-lattice (T1) time of water protons which is reflected as contrast in aqueous suspensions analyzed by magnetic resonance imaging. The interlayer space of dysprosium containing LDH was successfully intercalated with folate, ibuprofen and gallate ions, which are key molecules for recognition of some cancer cells and treatment of diseases. The paramagnetic property of the dysprosium-containing LDH detected in this work beside the ability to transport drugs open up the opportunity to design theranostic materials in a single crystal phase with nanometric dimensions.

  13. Slow magnetic relaxation in a hydrogen-bonded 2D array of mononuclear dysprosium(III) oxamates.

    Science.gov (United States)

    Fortea-Pérez, Francisco R; Vallejo, Julia; Julve, Miguel; Lloret, Francesc; De Munno, Giovanni; Armentano, Donatella; Pardo, Emilio

    2013-05-01

    The reaction of N-(2,6-dimethylphenyl)oxamic acid with dysprosium(III) ions in a controlled basic media afforded the first example of a mononuclear lanthanide oxamate complex exhibiting a field-induced slow magnetic relaxation behavior typical of single-ion magnets (SIMs). The hydrogen-bond-mediated self-assembly of this new bifunctional dysprosium(III) SIM in the solid state provides a unique example of 2D hydrogen-bonded polymer with a herringbone net topology.

  14. The influence of density of pressed iron powder samples on the quality of boride layers

    Directory of Open Access Journals (Sweden)

    Ivanov S.

    2003-01-01

    Full Text Available In this work the influence of the density of pressed iron powder on the quality of boride layers has been analysed. Examinations were performed on pressed samples of iron powder. The used granulation was 50-100, 100-150 and 150-200 mm. The samples were pressed under pressure of 200, 400, 600, 800 and 1000 MPa. Boroning was performed in a solid mixture based on boron-carbide, and was in principle the same for all samples. The obtained boride layers varied in depth and quality (porosity, the contact with metal. It has been observed that simultaneously with boroning sintering also occurred, and this fact offers a wide application possibility in the chemical-thermal treatment for sintered materials.

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

    Science.gov (United States)

    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.

  16. Boriding kinetics of Fe2B layers formed on AISI 1045 steel

    Directory of Open Access Journals (Sweden)

    Zuno-Silva J.

    2014-01-01

    Full Text Available In the present work, a diffusion model was suggested to study the growth kinetics of Fe2B layers grown on the AISI 1045 steel by the pack-boriding treatment. The generated boride layers were analyzed by optical microscopy and X-ray diffraction analysis. The applied diffusion model is based on the principle of mass conservation at the (Fe2B/ substrate interface. It was used to estimate the boron diffusion coefficients of Fe2B in the temperature range of 1123-1273 K. A validation of the model was also made by comparing the experimental Fe2B layer thickness obtained at 1253 K for 5 h of treatment with the predicted value. Basing on our experimental results, the boron activation energy was estimated as 180 kJ mol-1 for the AISI 1045 steel.

  17. Advancements in the search for superhard ultra-incompressible metal borides

    Energy Technology Data Exchange (ETDEWEB)

    Levine, Jonathan B.; Tolbert, Sarah H. [Department of Chemistry and Biochemistry, UCLA Los Angeles, CA (United States); California NanoSystems Institute, UCLA Los Angeles, CA (United States); Kaner, Richard B. [Department of Chemistry and Biochemistry, UCLA Los Angeles, CA (United States); California NanoSystems Institute, UCLA Los Angeles, CA (United States); Department of Materials Science and Engineering, UCLA Los Angeles, CA (United States)

    2009-11-23

    Dense transition metal borides have recently been identified as superhard materials that offer the possibility of ambient pressure synthesis compared to the conventional high pressure, high temperature approach. This feature article begins with a discussion of the relevant physical properties for this class of compounds, followed by a summary of the synthesis and properties of several transition metal borides. A strong emphasis is placed on correlating mechanical properties with electronic and atomic structure of these materials in an effort to better predict new superhard compounds. It concludes with a perspective of future research directions, highlighting some recent results and presenting several new ideas that remain to be tested. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

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

    Energy Technology Data Exchange (ETDEWEB)

    Kramp, S.; Febri, M.; Joubert, J.C. [CNRS UMR 5628, Saint Martin d`Heres (France)

    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,...).

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

    Science.gov (United States)

    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,…).

  20. Dysprosium-Catalyzed Growth of Single-Walled Carbon Nanotube Arrays on Substrates

    Directory of Open Access Journals (Sweden)

    Qian Yong

    2009-01-01

    Full Text Available Abstract In this letter, we report that dysprosium is an effective catalyst for single-walled carbon nanotubes (SWNTs growth via a chemical vapor deposition (CVD process for the first time. Horizontally superlong well-oriented SWNT arrays on SiO2/Si wafer can be fabricated by EtOH-CVD under suitable conditions. The structure and properties are characterized by scanning electron microscopy, transition electron microscopy, Raman spectroscopy and atomic force microscopy. The results show that the SWNTs from dysprosium have better structural uniformity and better conductivity with fewer defects. This rare earth metal provides not only an alternative catalyst for SWNTs growth, but also a possible method to generate high percentage of superlong semiconducting SWNT arrays for various applications of nanoelectronic device.

  1. Direct Search for keV Sterile Neutrino Dark Matter with a Stable Dysprosium Target

    CERN Document Server

    Lasserre, T; Cribier, M; Merle, A; Mertens, S; Vivier, M

    2016-01-01

    We investigate a new method to search for keV-scale sterile neutrinos that could account for Dark Matter. Neutrinos trapped in our galaxy could be captured on stable $^{163}$Dy if their mass is greater than 2.83~keV. Two experimental realizations are studied, an integral counting of $^{163}$Ho atoms in dysprosium-rich ores and a real-time measurement of the emerging electron spectrum in a dysprosium-based detector. The capture rates are compared to the solar neutrino and radioactive backgrounds. An integral counting experiment using several kilograms of $^{163}$Dy could reach a sensitivity for the sterile-to-active mixing angle $\\sin^2\\theta_{e4}$ of $10^{-5}$ significantly exceeding current laboratory limits. Mixing angles as low as $\\sin^2\\theta_{e4} \\sim 10^{-7}$ / $\\rm m_{^{163}\\rm Dy}\\rm{(ton)}$ could possibly be explored with a real-time experiment.

  2. Preparation of Dysprosium Ferrite/Polyacrylamide Magnetic Composite Microsphere and Its Characterization

    Institute of Scientific and Technical Information of China (English)

    Hidehiro Kumazawa; Wang Zhifeng; Zhou Lanxiang; Zhang Hong; Li Yourong; Zhang Ming

    2005-01-01

    Using the technique of microemulsion polymerization with nano-reactor, dysprosium ferrite/polyacrylamide magnetic composite microsphere was prepared by one-step method in a single inverse microemulsion. The structure, average particle size, morphology of composite microsphere were characterized by FTIR, XRD, TEM and TGA. The magnetic responsibility of composite microsphere was also investigated. The results indicate that the magnetic composite microsphere possess high magnetic responsibility and suspension stability.

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

    Energy Technology Data Exchange (ETDEWEB)

    Riley, M.A.; Brown, T.B.; Archer, D.E. [Florida State Univ., Tallahassee, FL (United States)] [and others

    1996-12-31

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

  4. Poly[[[μ3-N′-(carboxymethylethylenediamine-N,N,N′-triacetato]dysprosium(III] trihydrate

    Directory of Open Access Journals (Sweden)

    Xiaomei Zhuang

    2010-11-01

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

  5. Making two dysprosium atoms rotate - Einstein-de Haas effect revisited

    OpenAIRE

    Górecki, Wojciech; Rzążewski, Kazimierz

    2016-01-01

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

  6. Phosphor Dysprosium-Doped Layered Double Hydroxides Exchanged with Different Organic Functional Groups

    Directory of Open Access Journals (Sweden)

    David Ricardo Martínez Vargas

    2013-01-01

    Full Text Available The layers of a Zn/Al layered double hydroxide (LDH were doped with Dy3+ cations. Among some compositions, the Zn2+ : Al3+ : Dy3+ molar ratio equal to 30 : 9 : 1 presented a single crystalline phase. Organic anions with carboxylic, amino, sulfate, or phosphate functional groups were intercalated as single layers between LDH layers as confirmed by X-ray diffraction and infrared spectroscopy. Photoluminescence spectra of the nitrate intercalated LDH showed a wide emission band with strong intensity in the yellow region (around 574 nm, originated due to symmetry distortion of the octahedral coordination in dysprosium centers. Moreover, a broad red band emission was also detected apparently due to the presence of zinc oxide. The distorted symmetry of the dysprosium coordination environment, also confirmed by X-ray photoelectron spectroscopy analysis, was modified after the intercalation with phenyl phosphonate (PP, aspartate (Asp, adipate (Adip, and serinate (Ser anions; the emission as measured from PL spectra of these LDH was more intense in the blue region (ca. 486 nm, thus indicating an increase in symmetry of dysprosium octahedrons. The red emission band from zinc oxide kept the same intensity after intercalation of dodecyl sulfate (DDS. An additional emission of unknown origin at λ = 767 nm was present in all LDHs.

  7. Investigation of diffusion kinetics of plasma paste borided AISI 8620 steel using a mixture of B2O3 paste and B4C/SiC

    Indian Academy of Sciences (India)

    Ibrahim Gunes; Sukru Taktak; Cuma Bindal; Yilmaz Yalcin; Sukru Ulker; Yusuf Kayali

    2013-06-01

    In the present study, AISI 8620 steel was plasma paste borided by using various B2O3 paste mixture. The plasma paste boriding process was carried out in a dc plasma system at temperatures of 973, 1023 and 1073 K for 2, 5 and 7 h in a gas mixture of 70% H2 -30% Ar under a constant pressure of 10 mbar. The properties of the boride layer were evaluated by optical microscopy, X-ray diffraction, Vickers micro-hardness tester and the growth kinetics of the boride layers. X-ray diffraction analysis of boride layers on the surface of the steel revealed FeB and Fe2B phases. Depending on temperature and layer thickness, the activation energies of boron in steel were found to be 124.7 kJ/mol for 100% B2O3.

  8. Systematic study on surface and magnetostructural changes in Mn-substituted dysprosium ferrite by hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Rekha, G. [Department of Physics, College of Engineering Guindy, Anna University, Sardar Patel Road, Chennai 600025 (India); Tholkappiyan, R. [Department of Physics, College of Engineering Guindy, Anna University, Sardar Patel Road, Chennai 600025 (India); Department of Physics, College of Science, UAE University, Al-Ain 15551 (United Arab Emirates); Vishista, K., E-mail: raovishista@gmail.com [Department of Physics, College of Engineering Guindy, Anna University, Sardar Patel Road, Chennai 600025 (India); Hamed, Fathalla [Department of Physics, College of Science, UAE University, Al-Ain 15551 (United Arab Emirates)

    2016-11-01

    Highlights: • Garnet type Dy{sub 3}Fe{sub 5-x}Mn{sub x}O{sub 12} (x = 0–0.06) nanoparticles of 88.4–86.8 nm were synthesized by hydrothermal method. • The Dy, Mn, Fe and O elements in the ferrites were confirmed from XPS. • The multiple oxidation states of Fe and Mn ions, bonding energy and cationic distributions of the samples were examined by XPS. • The magnetic property shows ferromagnetic behavior from VSM technique. • The results from these studies are correlated with respect to Mn dopant. - Abstract: Dysprosium iron garnets are of scientific importance because of the wide range of magnetic properties that can be obtained in substituting dysprosium by a rare earth metal. In the present work, the effect of Mn substitution on magnetostructural changes in dysprosium ferrite nanoparticles is studied. Highly crystalline pure and Mn doped dysprosium ferrite nanoparticles were synthesized by hydrothermal method. The samples were calcined at 1100 °C for 2 h in air atmosphere which is followed by characterization using XRD, FT-IR analysis, SEM, XPS and VSM. The average crystallite size of synthesized samples were calculated by X-ray diffraction falls in the range of 88.4–86.8 nm and was found to be in cubic garnet structure. For further investigation of the structure and corresponding changes in the tetrahedral and octahedral stretching vibrational bonds, FT-IR was used. The synthesized samples consist of multiple oxidation (Fe{sup 3+} and Fe{sup 2+}) states for Fe ions and (Mn{sup 3+} and Mn{sup 2+}) Mn ions analyzed in three ways of Fe 2p and Mn 2p spectra from the XPS analysis. With respect to Mn dopant in Dy{sub 3}Fe{sub 5}O{sub 12}, the cationic distributions of elements were discussed from high resolution XPS spectra by peak position and shift, area, width. To find out the porous/void surface morphology of the sample, scanning electron microscopy was used. From XPS analysis, the presence of elements (Dy, Mn, Fe and O) and their composition in the

  9. Synthesis, structural characterization and in vitro testing of dysprosium containing silica particles as potential MRI contrast enhancing agents

    Energy Technology Data Exchange (ETDEWEB)

    Chiriac, L.B.; Trandafir, D.L. [Faculty of Physics & National Magnetic Resonance Center, Babeş-Bolyai University, Cluj-Napoca, RO-400084 (Romania); Interdisciplinary Research Institute on Bio-Nano-Sciences & Faculty of Physics, Babeş-Bolyai University, Cluj-Napoca, RO-400084 (Romania); Turcu, R.V.F. [Faculty of Physics & National Magnetic Resonance Center, Babeş-Bolyai University, Cluj-Napoca, RO-400084 (Romania); Todea, M. [Interdisciplinary Research Institute on Bio-Nano-Sciences & Faculty of Physics, Babeş-Bolyai University, Cluj-Napoca, RO-400084 (Romania); Simon, S., E-mail: simons@phys.ubbcluj.ro [Faculty of Physics & National Magnetic Resonance Center, Babeş-Bolyai University, Cluj-Napoca, RO-400084 (Romania); Interdisciplinary Research Institute on Bio-Nano-Sciences & Faculty of Physics, Babeş-Bolyai University, Cluj-Napoca, RO-400084 (Romania)

    2016-11-01

    Highlights: • Dysprosium containing silica microparticles obtained by freeze and spray drying. • Higher structural units interconnection achieved in freeze vs. spray dried samples. • Dy occurance on the outermost layer of the microparticles evidenced by XPS. • Enhanced MRI contrast observed for freeze dried samples with 5% mol Dy{sub 2}O{sub 3}. - Abstract: The work is focused on synthesis and structural characterization of novel dysprosium-doped silica particles which could be considered as MRI contrast agents. Sol-gel derived silica rich particles obtained via freeze-drying and spray-drying processing methods were structurally characterized by XRD, {sup 29}Si MAS-NMR and XPS methods. The occurrence of dysprosium on the outermost layer of dysprosium containing silica particles was investigated by XPS analysis. The MRI contrast agent characteristics have been tested using RARE-T{sub 1} and RARE-T{sub 2} protocols. The contrast of MRI images delivered by the investigated samples was correlated with their local structure. Dysprosium disposal on microparticles with surface structure characterised by decreased connectivity of the silicate network units favours dark T{sub 2}-weighted MRI contrast properties.

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

    OpenAIRE

    Shigeaki Ono; Takumi Kikegawa

    2016-01-01

    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 we...

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Wade, C.S.; Park, H.G.; Hoagland, R.G. (Ohio State Univ., Columbus (USA))

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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  15. Boron-dependency of molybdenum boride electrocatalysts for the hydrogen evolution reaction

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hyounmyung; Encinas, Andrew; Fokwa, Boniface P.T. [Department of Chemistry, University of California, Riverside, CA (United States); Department of Chemical and Environmental Engineering, University of California, Riverside, CA (United States); Scheifers, Jan P.; Zhang, Yuemei [Department of Chemistry, University of California, Riverside, CA (United States)

    2017-05-08

    Molybdenum-based materials have been considered as alternative catalysts to noble metals, such as platinum, for the hydrogen evolution reaction (HER). We have synthesized four binary bulk molybdenum borides Mo{sub 2}B, α-MoB, β-MoB, and MoB{sub 2} by arc-melting. All four phases were tested for their electrocatalytic activity (linear sweep voltammetry) and stability (cyclic voltammetry) with respect to the HER in acidic conditions. Three of these phases were studied for their HER activity and by X-ray photoelectron spectroscopy (XPS) for the first time; MoB{sub 2} and β-MoB show excellent activity in the same range as the recently reported α-MoB and β-Mo{sub 2}C phases, while the molybdenum richest phase Mo{sub 2}B show significantly lower HER activity, indicating a strong boron-dependency of these borides for the HER. In addition, MoB{sub 2} and β-MoB show long-term cycle stability in acidic solution. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Pulsed nanocrystalline plasma electrolytic boriding as a novel method for corrosion protection of CP-Ti (Part 1: Different frequency and duty cycle)

    Indian Academy of Sciences (India)

    M Kh Aliev; A Saboor

    2007-12-01

    Potentiodynamic polarization and electrochemical impedance spectroscopy were employed to test borided CP-Ti, treated by a relatively new method called pulsed plasma electrolytic boriding. The results show excellent corrosion resistance for modified CP-Ti. The effect of frequency and duty cycle of pulsed current was investigated. It was found that pulse frequency and duty cycle affect the size and porosity of nanocrystalline borides and by controlling these effective parameters, surface modification can render the CP-Ti material extremely corrosion resistant as a biomaterial.

  17. Influence of exchange splitting on optical properties in gadolinium and dysprosium single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Knyazev, Yu.V.; Bolotin, G.A. (AN SSSR, Sverdlovsk. Inst. Fiziki Metallov)

    1984-12-01

    The temperature dependences of optical conductivity in gadolinium and dysprosium single crystals at the light wave vector polarization along a hexagonal axis and in the basis plane are considered. A substantial anisotropy of interzonal absorption has been found. The sample transition into magnetically ordered state is shown to be accompanied by the emergence of resonance absorption peaks in the near infrared spectral region. The manifestation of these peculiarities is associated with quantum electron transitions between the s-, d-f- interaction-split energy bands near the Fermi level. Main peculiarities of the experimental spectrum of gadolinium optical conductivity found their reflection in theoretically calculated dispersion dependence.

  18. Therapeutic application of dysprosium-165-FHMA in the treatment of rheumatoid knee effusions

    Energy Technology Data Exchange (ETDEWEB)

    English, R.J.; Zalutsky, M.; Venkatesan, P.; Sledge, C.B.

    1986-03-01

    Radiation synovectomy utilizing a variety of radionuclides has proven to be an effective technique in the treatment of rheumatoid arthritis. The recent introduction of the short-lived radionuclide, Dysprosium-165 (/sup 165/Dy), as a replacement for the longer-lived radiocolloids has reduced nontarget dosimetry caused by leakage of the agent from the articular cavity. A review of the methods and status of radiation synovectomy, and the application of /sup 165/Dy-ferric hydroxide macroaggregates (FHMA) as an alternative therapeutic agent is described.

  19. Properties of dysprosium-doped gallium lanthanum sulfide fiber amplifiers operating at 1.3 microm.

    Science.gov (United States)

    Samson, B N; Schweizer, T; Hewak, D W; Laming, R I

    1997-05-15

    In light of recent progress in the fabrication of gallium lanthanum sulfide (GaLaS) fibers, we have modeled the performance of dysprosium-doped GaLaS fiber amplifiers operating at 1.3 microm . Based on experimental data, we find that the incorporation of a codopant (terbium) in the fiber core significantly shortens the optimum amplifier length from >30 m to approximately 3 m . Such a device may be practical, given the fiber losses currently achieved in GaLaS fibers.

  20. Effect of dysprosium on the kinetics and structural transformations during the decomposition of the supersaturated solid solution in magnesium-samarium alloys

    Science.gov (United States)

    Rokhlin, L. L.; Luk'yanova, E. A.; Tabachkova, N. Yu.; Dobatkina, T. V.; Tarytina, I. E.; Korol'kova, I. G.

    2017-03-01

    The effect of dysprosium added in the amounts such that it does not form an individual phase in equilibrium with solid magnesium on the decomposition of the supersaturated magnesium solid solution in Mg-Sm alloys is studied. The presence of dysprosium in Mg-Sm alloys is found to retard the decomposition of the supersaturated magnesium solid solution and to increase the hardening effect upon aging. When these alloys are aged, dysprosium is partly retained in the magnesium solid solution and partly enters into the compositions of the phases that form during the decomposition of the solid solution and are characteristic of Mg-Sm alloys.

  1. Cyclic single-molecule magnets: from the odd-numbered heptanuclear to a dimer of heptanuclear dysprosium clusters.

    Science.gov (United States)

    Tian, Haiquan; Bao, Song-Song; Zheng, Li-Min

    2016-02-01

    A heptanuclear and a dimer of heptanuclear dysprosium clusters (Dy7 and Dy14) have been successfully synthesized by ingenious coalescence of the single and double pyrazinyl hydrazone as well as phosphonate ligands. The complexes feature the largest odd-numbered cyclic lanthanide clusters reported thus far. Both exhibit single molecule magnet behaviors at low temperature.

  2. A comparison of the effects of symmetry and magnetoanisotropy on paramagnetic relaxation in related dysprosium single ion magnets.

    Science.gov (United States)

    Williams, Ursula J; Mahoney, Brian D; DeGregorio, Patrick T; Carroll, Patrick J; Nakamaru-Ogiso, Eiko; Kikkawa, James M; Schelter, Eric J

    2012-06-07

    Dysprosium complexes of the tmtaa(2-) ligand were synthesized and characterized by X-band EPR and magnetism studies. Both complexes demonstrate magnetoanisotropy and slow paramagnetic relaxation. Comparison of these compounds with the seminal phthalocyanine complex [Dy(Pc)(2)](-) shows the azaannulide complexes are more susceptible to relaxation through non-thermal pathways.

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

    Energy Technology Data Exchange (ETDEWEB)

    Sánchez Lafarga, Ana Karen; Pacheco Moisés, Fermín P. [Departamento de Química, Universidad de Guadalajara, Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico); Gurinov, Andrey [Research Resources Center for Magnetic Resonance, Saint Petersburg State University, Universitetskij pr. 26, 198504 St. Petersburg (Russian Federation); Ortiz, Genaro Gabriel [Laboratorio Desarrollo-Envejecimiento, Enfermedades Neurodegenerativas, Centro de Investigación Biomédica de Occidente (CIBO), Instituto Mexicano de Seguro Social (IMSS), Guadalajara, Jalisco (Mexico); Carbajal Arízaga, Gregorio Guadalupe, E-mail: gregoriocarbajal@yahoo.com.mx [Departamento de Química, Universidad de Guadalajara, Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico)

    2015-03-01

    The development of probes for biomedical applications demands materials with low toxicity levels besides fluorescence or magnetic properties to be detected by confocal microscopes or MRI resonators. Several drug delivery systems or other biomedical materials prepared with hydroxyapatite have been proposed, however, toxicity effects might arise when the size of particles is nanometric. In this study, hydroxyapatite functionalized with glucuronic or folic acids presented lower oxidative stress, measured from lipoperoxides and nitric oxide indicators in rats than pure hydroxyapatite. In separated experiments, hydroxyapatite was doped with dysprosium cations by coprecipitation producing a single crystal phase with fluorescent properties easily visualized by confocal microscopy when excited at 488 nm. These particles also presented the ability to modify the proton relaxation time in T1 maps collected by magnetic resonance imaging. These modified hydroxyapatite nanoparticles could be candidates to design bimodal probes with low toxicity. - Highlights: • Hydroxyapatite functionalized with glucuronic acid reduced oxidative stress in rats. • Functionalization with folic acid reduced oxidative stress in rats. • Dysprosium doping does not affect the crystalline structure of hydroxyapatite. • Dysprosium doped particles are visible in fluorescent microscope. • Dysprosium doped particles act as MRI contrast agents.

  4. Tuning Slow Magnetic Relaxation in a Two-Dimensional Dysprosium Layer Compound through Guest Molecules.

    Science.gov (United States)

    Chen, Qi; Li, Jian; Meng, Yin-Shan; Sun, Hao-Ling; Zhang, Yi-Quan; Sun, Jun-Liang; Gao, Song

    2016-08-15

    A novel two-dimensional dysprosium(III) complex, [Dy(L)(CH3COO)]·0.5DMF·H2O·2CH3OH (1), has been successfully synthesized from a new pyridine-N-oxide (PNO)-containing ligand, namely, N'-(2-hydroxy-3-methoxybenzylidene)pyridine-N-oxidecarbohydrazide (H2L). Single-crystal X-ray diffraction studies reveal that complex 1 is composed of a dinuclear dysprosium subunit, which is further extended by the PNO part of the ligand to form a two-dimensional layer. Magnetic studies indicate that complex 1 shows well-defined temperature- and frequency-dependent signals under a zero direct-current (dc) field, typical of slow magnetic relaxation with an effective energy barrier Ueff of 33.6 K under a zero dc field. Interestingly, powder X-ray diffraction and thermogravimetric analysis reveal that compound 1 undergoes a reversible phase transition that is induced by the desorption and absorption of methanol and water molecules. Moreover, the desolvated sample [Dy(L)(CH3COO)]·0.5DMF (1a) also exhibits slow magnetic relaxation but with a higher anisotropic barrier of 42.0 K, indicating the tuning effect of solvent molecules on slow magnetic relaxation.

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

    Energy Technology Data Exchange (ETDEWEB)

    Omar, R. S., E-mail: ratnasuffhiyanni@gmail.com; Wagiran, H., E-mail: husin@utm.my; Saeed, M. A. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310 Johor Bahru (Malaysia)

    2016-01-22

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

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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).

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    2015-09-16

    elements from the Hf family (i.e., Hf, Ti and Zr ) into a capillary to understand the effects of surface tension and viscosity during processing of melts...project primarily investigated computationally the infusion of liquid elements from the Hf family (i.e., Hf, Ti and Zr ) into a capillary to understand the... effects of surface tension and viscosity during processing of melts with a packed bed of B4C to form boride-carbide precipitates. Although the

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

    OpenAIRE

    Kolmogorov, Aleksey N.; Curtarolo, Stefano

    2006-01-01

    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 initioa data mining of intermetallic compounds we made an unexpected discovery: even in such a well-studied class of systems as metal borides t...

  13. Luminescent properties of dysprosium(Ⅲ) ions in LaAlO3 nanocrystallites

    Institute of Scientific and Technical Information of China (English)

    K. Lema(n)ski; P.J. Dere(n)

    2011-01-01

    The absorption and emission spectra as well as decay time profile of Dy3+ ions in LaAlO3 nanocrystals were analyzed.The crystal structure of LaAlO3 was confirmed from XRD measurement.The emission peaks from blue to red came from main emitting level of dysprosium 4F9/2 to the ground and other excited levels of Dy3+ ions.Cross relaxation process led to non-radiative quenching of luminescence,so that the lifetime of the 4F9/2 energy level ions decreased with increasing amount of doped Dy3+ ions.The cross relaxation transfer rates were experimentally determined as a function of Dy3+ concentration.

  14. Magnetic ordering temperatures in rare earth metal dysprosium under ultrahigh pressures

    Science.gov (United States)

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

    2014-04-01

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

  15. Electrochemical behaviour of dysprosium in the eutectic LiCl-KCl at W and Al electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Castrillejo, Y. [Dpto de Quimica Analitica, Facultad de Ciencias, Universidad de Valladolid, Prado de la Magdalena s/n, 47005 Valladolid (Spain)]. E-mail: ycastril@qa.uva.es; Bermejo, M.R. [Dpto de Quimica Analitica, Facultad de Ciencias, Universidad de Valladolid, Prado de la Magdalena s/n, 47005 Valladolid (Spain); Barrado, A.I. [Dpto de Quimica Analitica, Facultad de Ciencias, Universidad de Valladolid, Prado de la Magdalena s/n, 47005 Valladolid (Spain); Pardo, R. [Dpto de Quimica Analitica, Facultad de Ciencias, Universidad de Valladolid, Prado de la Magdalena s/n, 47005 Valladolid (Spain); Barrado, E. [Dpto de Quimica Analitica, Facultad de Ciencias, Universidad de Valladolid, Prado de la Magdalena s/n, 47005 Valladolid (Spain); Martinez, A.M. [Department of Materials Technology, Sem Saelands vei 6, 7491 Trondheim (Norway)

    2005-03-15

    The electrochemical behaviour of DyCl{sub 3} was studied in the eutectic LiCl-KCl at different temperatures. The cathodic reaction can be written:Dy(III)+3e-bar Dy(0)which can be divided in two very close cathodic steps:Dy(III)+1e-bar Dy(II)andDy(II)+2e-bar Dy(0)Transient electrochemical techniques, such as cyclic voltammetry, chronopotentiometry, and chronoamperometry were used in order to study the reaction mechanism and the transport parameters of electroactive species at a tungsten electrode. The results showed that in the eutectic LiCl-KCl, electrocrystallization of dysprosium seems to be the controlling electrochemical step. Chronoamperometric studies indicated instantaneous nucleation of dysprosium with three dimensional growth of the nuclei whatever the applied overpotential.Mass transport towards the electrode is a simple diffusion process, and the diffusion coefficient of the electroactive species, i.e. Dy(III), has been calculated. The validity of the Arrhenius law was also verified by plotting the variation of the logarithm of the diffusion coefficient versus 1/T.In addition, the electrode reactions of the LiCl-KCl-DyCl{sub 3} solutions at an Al wire were also investigated by cyclic voltammetry and open circuit chronopotentiometry. The redox potential of the Dy(III)/Dy couple at the Al electrode was observed at more positive potentials values than those at the inert electrode. This potential shift was thermodynamically analyzed by a lowering of activity of Dy in the metal phase due to the formation of intermetallic compounds.

  16. Structural, optical, thermal, mechanical and dielectric studies of Sulfamic acid single crystals: An influence of dysprosium (Dy3+) doping

    Science.gov (United States)

    Singh, Budhendra; Shkir, Mohd.; AlFaify, S.; Kaushal, Ajay; Nasani, Narendar; Bdikin, Igor; Shoukry, H.; Yahia, I. S.; Algarni, H.

    2016-09-01

    Sulfamic acid is a potential material that exhibits excellent optical properties. A good quality, pure and dysprosium (Dy3+) doped (2.5 and 5 mol %) Sulfamic acid (SA) single crystals were grown successfully by slow cooling method. Structural study revealed a slight change in its lattice parameters and volume, suggesting the successful incorporation of Dy3+ in crystal system. The existence of dysprosium in the system was also confirmed. Presence of various vibrational modes was confirmed. Optical transparency was found to have a significant effect with variation in the doping concentration. Furthermore, a marked enhancement in its mechanical parameters with doping was also identified by nanoindentation technique. Etching study was also performed on the grown crystals to study the etch-pit formation and growth mechanism. Effect of doping on the thermal stability was analysed. All the results were compared and discussed in detail to get insight of the effect of doping concentration on Sulfamic acid crystal.

  17. Optical trapping of ultracold dysprosium atoms: transition probabilities, dynamic dipole polarizabilities and van der Waals $C_6$ coefficients

    CERN Document Server

    Li, Hui; Dulieu, Olivier; Nascimbene, Sylvain; Lepers, Maxence

    2016-01-01

    The efficiency of optical trapping of ultracold atoms depend on the atomic dynamic dipole polarizability governing the atom-field interaction. In this article, we have calculated the real and imaginary parts of the dynamic dipole polarizability of dysprosium in the ground and first excited level. Due to the high electronic angular momentum of those two states, the polarizabilities possess scalar, vector and tensor contributions that we have computed, on a wide range of trapping wavelengths, using the sum-over-state formula. Using the same formalism, we have also calculated the $C_6$ coefficients characterizing the van der Waals interaction between two dysprosium atoms in the two lowest levels. We have computed the energies of excited states and the transition probabilities appearing in the sums, using a combination of \\textit{ab initio} and least-square-fitting techniques provided by the Cowan codes and extended in our group. Regarding the real part of the polarizability, for field frequencies far from atomic...

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

    Science.gov (United States)

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

    2013-11-21

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

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Shigeaki Ono

    2016-12-01

    Full Text Available 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 (∂BT/∂TV = 0.095 (GPa/K and α0 = 2.49 × 10−5 K−1.

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

    Science.gov (United States)

    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.

  2. Evaluating United States and world consumption of neodymium, dysprosium, terbium, and praseodymium in final products

    Science.gov (United States)

    Hart, Matthew

    This paper develops scenarios of future rare-earth-magnet metal (neodymium, dysprosium, terbium, and praseodymium) consumption in the permanent magnets used in wind turbines and hybrid electric vehicles. The scenarios start with naive base-case scenarios for growth in wind-turbine and hybrid-electric-vehicle sales over the period 2011 to 2020, using historical data for each good. These naive scenarios assume that future growth follows time trends in historical data and does not depend on any exogenous variable. Specifically, growth of each technological market follows historical time trends, and the amount of rare earths used per unit of technology remains fixed. The chosen reference year is 2010. Implied consumptions of the rare earth magnet metals are calculated from these scenarios. Assumptions are made for the material composition of permanent magnets, the market share of permanent-magnet wind turbines and vehicles, and magnet weight per unit of technology. Different scenarios estimate how changes in factors like the material composition of magnets, growth of the economy, and the price of a substitute could affect future consumption. Each scenario presents a different method for reducing rare earth consumption and could be interpreted as potential policy choices. In 2010, the consumption (metric tons, rare-earth-oxide equivalent) of each rare-earth-magnet metal was as follows. Total neodymium consumption in the world for both technologies was 995 tons; dysprosium consumption was 133 tons; terbium consumption was 50 tons; praseodymium consumption was zero tons. The base scenario for wind turbines shows there could be strong, exponential growth in the global wind turbine market. New U.S. sales of hybrid vehicles would decline (in line with the current economic recession) while non-U.S. sales increase through 2020. There would be an overall increase in the total amount of magnetic rare earths consumed in the world. Total consumption of each rare earth in the short

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

    Directory of Open Access Journals (Sweden)

    Lkhamsuren Bayarjargal

    2011-09-01

    Full Text Available 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.

  4. Intermediate valence behavior of ternary cerium and uranium transition metal borides

    Science.gov (United States)

    Yang, K. N.; Torikachvili, M. S.; Maple, M. B.; Ku, H. C.

    1984-09-01

    Low-temperature specific heat, electrical resistivity, ac magnetic susceptibility, and dc magnetization measurements were made on ternary cerium and uranium transition metal borides with the general formula CeT3B2 (T=Co, Ru, Rh, and Ir) and UT3B2 (T=Co, Ru, and Ir). The compound CeRu3B2 was found to exhibit superconductivity below 0.68 K. The values of the electronic specific heat coefficient range from 9.7 mJ/mole-K2 for CeCo3B2 to 64 mJ/mole-K2 for UIr3B2. The electrical resistivity versus temperature curves of all of the compounds exhibit negative curvature and are reminiscent of valence fluctuation behavior. In the case of CeIr3B2, the electrical resistivity attains a maximum value at 180 K, while the dc magnetic susceptibility has a temperature dependence that is typical of intermediate valence Ce compounds, approaching a finite value at zero temperature. The electrical resistivity of the ferromagnetic compound CeRh3B2 reveals a rapid decrease in spin disorder resistivity below 120 K. The dc magnetic susceptibility of this material can be described as the sum of a constant term and a Curie-Weiss contribution with an effective magnetic moment of 1.01 µB per formula unit and a Curie-Weiss temperature of 119 K. Magnetization measurements on CeRh3B2 yield a saturation magnetic moment of 0.37 µB per formula unit and a Curie temperature of 113 K.

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

    Science.gov (United States)

    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.

  6. Luminescence features of dysprosium and phosphorus oxide co-doped lithium magnesium borate glass

    Science.gov (United States)

    Hashim, S.; Mhareb, M. H. A.; Ghoshal, S. K.; Alajerami, Y. S. M.; Saripan, M. I.; Bradley, D. A.

    2017-08-01

    Lithium magnesium borate (LMB) glass system co-doped with the oxides of dysprosium (Dy2O3) and phosphorus (P2O5) were synthesized using melt-quenching method. Prepared samples were characterized using various techniques to determine the effects of co-dopants concentration variation on their thermoluminescence (TL) and photoluminescence (PL) properties. TL glow curves of LMB:0.5Dy sample revealed a single prominent peak at Tm=190 °C, where TL intensity was enhanced by a factor of 2.5 with the increase of P2O5 concentration up to 1 mol%. This enhancement was accompanied by a shift in Tm towards higher temperature. Good linearity in the range of 1-100 Gy with linear correlation coefficient of 0.998 was achieved. PL spectra displayed two significant peaks centred at 481 nm and 573 nm. These attractive luminescence features of the proposed glass system may be useful for the development of radiation dosimetry.

  7. Single-molecule magnet behavior for an antiferromagnetically superexchange-coupled dinuclear dysprosium(III) complex.

    Science.gov (United States)

    Long, Jérôme; Habib, Fatemah; Lin, Po-Heng; Korobkov, Ilia; Enright, Gary; Ungur, Liviu; Wernsdorfer, Wolfgang; Chibotaru, Liviu F; Murugesu, Muralee

    2011-04-13

    A family of five dinuclear lanthanide complexes has been synthesized with general formula [Ln(III)(2)(valdien)(2)(NO(3))(2)] where (H(2)valdien = N1,N3-bis(3-methoxysalicylidene)diethylenetriamine) and Ln(III) = Eu(III)1, Gd(III)2, Tb(III)3, Dy(III)4, and Ho(III)5. The magnetic investigations reveal that 4 exhibits single-molecule magnet (SMM) behavior with an anisotropic barrier U(eff) = 76 K. The step-like features in the hysteresis loops observed for 4 reveal an antiferromagnetic exchange coupling between the two dysprosium ions. Ab initio calculations confirm the weak antiferromagnetic interaction with an exchange constant J(Dy-Dy) = -0.21 cm(-1). The observed steps in the hysteresis loops correspond to a weakly coupled system similar to exchange-biased SMMs. The Dy(2) complex is an ideal candidate for the elucidation of slow relaxation of the magnetization mechanism seen in lanthanide systems.

  8. A comparative study of donor formation in dysprosium, holmium, and erbium implanted silicon

    Energy Technology Data Exchange (ETDEWEB)

    Emtsev, V.V.; Emtsev, V.V. Jr.; Poloskin, D.S.; Shek, E.I.; Sobolev, N.A. [Division of Solid State Electronics, Ioffe Physicotechnical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation)

    1998-12-01

    Formation of donor centers in Czochralski grown silicon doped with dysprosium, holmium, and erbium is discussed. Donor states of three kinds are introduced in the implanted layers after annealing at T=700C. Shallow donor states with ionization energies between 20 and 40 meV are attributed to oxygen -related thermal donors. Other donor centers in the energy range of E{sub C}-(60...70) meV and E{sub C}-(100...120) meV appear to be dependent on dopants. After a 900C anneal strong changes in the donor formation are observed only in silicon doped with erbium. Instead of donors at E{sub C}-(118{+-}5) meV, new donor centres at E{sub C}-(145{+-}5) meV are formed. Reportedly, the latter ones are involved in the excitation process of the Er{sup 3+} ions with a characteristic luminescence line at {approx}1.54 {mu}m. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

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

    Science.gov (United States)

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

    2015-12-01

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

  10. Optical properties of zinc borotellurite glass doped with trivalent dysprosium ion

    Science.gov (United States)

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

    2017-04-01

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

  11. Isolation of {sup 163}Ho from dysprosium target material by HPLC for neutrino mass measurements

    Energy Technology Data Exchange (ETDEWEB)

    Mocko, Veronika; Taylor, Wayne A.; Nortier, Francois M.; Engle, Jonathan W.; Pollington, Anthony D.; Kunde, Gerd J.; Rabin, Michael W.; Birnbaum, Eva R. [Los Alamos National Laboratory, Los Alamos, NM (United States). Chemistry Div.; Barnhart, Todd E.; Nickles, Robert J. [Univ. Wisconsinn, Madison, WI (United States). Dept. of Medical Physics

    2015-07-01

    The rare earth isotope {sup 163}Ho is of interest for neutrino mass measurements. This report describes the isolation of {sup 163}Ho from a proton-irradiated dysprosium target and its purification. A Dy metal target was irradiated with 16 MeV protons for 10 h. After target dissolution, {sup 163}Ho was separated from the bulk Dy via cation-exchange high performance liquid chromatography using 70 mmol dm{sup -3} α-hydroxyisobutyric acid as the mobile phase. Subsequent purification of the collected Ho fraction was performed to remove the α-hydroxyisobutyrate chelating agent and to concentrate the Ho in a low ionic strength aqueous matrix. The final solution was characterized by MC-ICP-MS to determine the {sup 163}Ho/{sup 165}Ho ratio, {sup 163}Ho and the residual Dy content. The HPLC purification process resulted in a decontamination factor 1.4 x 10{sup 5} for Dy. The isolated Ho fraction contained 24.8 ± 1.3 ng of {sup 163}Ho corresponding to holmium recovery of 72 ± 3%.

  12. Microstructural evaluation of a low carbon steel submitted to boriding treatment pre and post GTAW welding; Avaliacao microestrutural de um aco de baixo carbono submetido ao tratamento de boretacao pre e pos-soldagem GTAW

    Energy Technology Data Exchange (ETDEWEB)

    Pollnow, Edilson Nunes; Osorio, Alice Goncalves, E-mail: edilson.pollnow@hotmail.com, E-mail: osorio.alice@gmail.com [Universidade Federal de Pelotas (CDTec/UFPel), Pelotas, RS (Brazil). Centro de Desenvolvimento Tecnologico; Araujo, Douglas Bezerra de, E-mail: dbaraujo@ufu.br [Universidade Federal de Uberlandia (FEMEC/UFU), Uberlandia, MG (Brazil). Faculdade de Engenharia Mecanica; Passos, Thais Andrezza dos; Souza, Daniel, E-mail: thais.andrezza.passos@gmail.com, E-mail: danielsouza@furg.br [Universidade Federal do Rio Grande (EE/FURG), Rio Grande, RS (Brazil). Escola de Engenharia

    2017-04-15

    Studies on surface engineering area are given great importance due to the improvement that surface modifications provide to materials. With a global market that has the need to provide parts and equipment with extended service life and low cost, to support stringent requests and thus maintain its high performance, surface treatments may bring what was impossible into reality. Among the surface treatments that have received attention recently, we have the thermochemical process of boriding. The boriding process consists of saturate the surface of steels and metal alloys with boron. This saturation provides an increase in the surface properties not inherent to the base metal, such as hardness, resistance to abrasion and corrosion. Although the properties of boriding steels have already been studied, the effects that the boriding process perform on the steel during or after the welding processes are not known. Hence, it is the purpose of this study to evaluate the microstructure of a low carbon steel treated with boriding before and after GTAW welding. The results indicated poor metallurgical weldability of low carbon steel with boride layer, with the presence of solidification cracks. Nonetheless, the steel welded previous to boring treatment presented a more ductile nucleus, with harder surface. Although the values of hardness within the nucleus of the steel had dropped drastically at the welded zone after the boring, the surface of this steel showed higher values of hardness due to the boriding layer. This fact should be considered when applications where wear resistance is needed. (author)

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  15. Acute dysprosium toxicity to Daphnia pulex and Hyalella azteca and development of the biotic ligand approach.

    Science.gov (United States)

    Vukov, Oliver; Smith, D Scott; McGeer, James C

    2016-01-01

    The toxicological understanding of rare earth elements (REEs) in the aquatic environment is very limited but of increasing concern. The objective of this research is to compare the toxicological effect of the REE dysprosium to the freshwater invertebrates Daphnia pulex and Hyalella azteca and in the more sensitive organism, understand the toxicity modifying influence of Ca, Na, Mg, pH and dissolved organic matter (DOM). Standard methods (Environment Canada) were followed for testing and culture in media of intermediate hardness (60mg CaCO3 mg/L) at pH 7.8 with Ca at 0.5, Na 0.5, Mg 0.125 (mM) and 23°C. Acute toxicity tests were done with azteca and D. pulex revealed Hyalella to be 1.4 times more sensitive than Daphnia. Additions of Ca and Na but not Mg provided significant protection against Dy toxicity to Hyalella. Similarly, low pH was associated with reduction in toxicity. Exposures which were pH buffered with and without MOPS were significantly different and indicated that MOPS enhanced Dy toxicity. DOM also mitigated Dy toxicity. Biotic ligand based parameters (LogK values) were calculated based on free ion relationships as determined by geochemical equilibrium modeling software (WHAM ver. 7.02). The logK value for Dy(3+) toxicity to Hyalella was 7.75 while the protective influence of Ca and Na were 3.95 and 4.10, respectively. This study contributes data towards the development of site specific water quality guidelines and criteria for Dy and possibly REEs in general and offers insight into the complex bio-geochemical nature of this element.

  16. Optical trapping of ultracold dysprosium atoms: transition probabilities, dynamic dipole polarizabilities and van der Waals C 6 coefficients

    Science.gov (United States)

    Li, H.; Wyart, J.-F.; Dulieu, O.; Nascimbène, S.; Lepers, M.

    2017-01-01

    The efficiency of the optical trapping of ultracold atoms depends on the atomic dynamic dipole polarizability governing the atom-field interaction. In this article, we have calculated the real and imaginary parts of the dynamic dipole polarizability of dysprosium in the ground and first excited levels. Due to the high electronic angular momentum of those two states, the polarizabilities possess scalar, vector and tensor contributions that we have computed, on a wide range of trapping wavelengths, using the sum-over-state formula. Using the same formalism, we have also calculated the C 6 coefficients characterizing the van der Waals interaction between two dysprosium atoms in the two lowest levels. We have computed the energies of excited states and the transition probabilities appearing in the sums, using a combination of ab initio and least-square-fitting techniques provided by the Cowan codes and extended in our group. Regarding the real part of the polarizability, for field frequencies far from atomic resonances, the vector and tensor contributions are two-orders-of-magnitude smaller than the scalar contribution, whereas for the imaginary part, the vector and tensor contributions represent a noticeable fraction of the scalar contribution. Finally, our anisotropic C 6 coefficients are much smaller than those published in the literature.

  17. 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

    Science.gov (United States)

    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.

  18. Synthesis, characterization and investigation of thermoelectric properties of selected metal borides; Synthese, Charakterisierung und Untersuchung thermoelektrischer Eigenschaften ausgewaehlter Metallboride

    Energy Technology Data Exchange (ETDEWEB)

    Stober, Frederick

    2012-06-04

    The present work deals with the high-temperature thermoelectric properties of transition metal [eg V, Cr, Mn, Ni, Cu] and lanthanide [e.g. Sc, Y, Gd, Er, Dy]-borides. In particular, intercalation compounds of beta-rhombohedral boron, compounds of the type MB{sub 66}, dodecaborides and hexaborides were examined. In the case of intercalation compounds of beta-rhombohedral boron it was found that the incorporation of metals such as Sc, Mn or Cu result in favorable thermoelectric properties. The reason is most likely the preferred occupation of the metal position M2 instead of M4. Composites, for example, DyB{sub 66}-DyB{sub 12} show high electrical conductivities, high Seebeck effects at high temperatures due to the presence of DyB{sub 12} and low thermal conductivities as a result of the DyB{sub 66} matrix. At 1100K the composite DyB{sub 66}-DyB{sub 12} shows a ZT value of 0.55, thus exceeding the ZT of boron carbide (B{sub 13}C{sub 2}) at this temperature which is considered the best p-type boride material. A composite of ErB{sub 12}-ErB{sub 4}-ErB{sub 2} has negative Seebeck coefficients and shows a ZT value of 0.5 at 840K. Furthermore, the structure of tetragonal Scandiumdodecaboride ScB{sub 12} was solved on the basis of synchrotron data from a crystalline powder, after it has been debated for decades but never fully resolved.

  19. Acute dysprosium toxicity to Daphnia pulex and Hyalella azteca and development of the biotic ligand approach

    Energy Technology Data Exchange (ETDEWEB)

    Vukov, Oliver, E-mail: vuko3930@mylaurier.ca [Biology Department, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5 (Canada); Smith, D. Scott [Chemistry Department, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5 (Canada); McGeer, James C. [Biology Department, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5 (Canada)

    2016-01-15

    The toxicological understanding of rare earth elements (REEs) in the aquatic environment is very limited but of increasing concern. The objective of this research is to compare the toxicological effect of the REE dysprosium to the freshwater invertebrates Daphnia pulex and Hyalella azteca and in the more sensitive organism, understand the toxicity modifying influence of Ca, Na, Mg, pH and dissolved organic matter (DOM). Standard methods (Environment Canada) were followed for testing and culture in media of intermediate hardness (60 mg CaCO{sub 3} mg/L) at pH 7.8 with Ca at 0.5, Na 0.5, Mg 0.125 (mM) and 23 °C. Acute toxicity tests were done with <24 h old neonates for 48 h in the case of D. pulex and with 2–9 days old offspring for 96 h tests with Hyalella. The potential protective effect of cationic competition was tested with Ca (0.5–2.0 mM), Na (0.5–2.0 mM) and Mg (0.125–0.5 mM). The effect of pH (6.5–8.0) and Suwannee River DOM complexation (at dissolved organic carbon (DOC) concentrations of 9 and 13 mg C/L) were evaluated. Dissolved Dy concentrations were lower than total (unfiltered) indicating precipitation, particularly at higher concentrations. Acute toxicity of Dy to H. azteca and D. pulex revealed Hyalella to be 1.4 times more sensitive than Daphnia. Additions of Ca and Na but not Mg provided significant protection against Dy toxicity to Hyalella. Similarly, low pH was associated with reduction in toxicity. Exposures which were pH buffered with and without MOPS were significantly different and indicated that MOPS enhanced Dy toxicity. DOM also mitigated Dy toxicity. Biotic ligand based parameters (Log K values) were calculated based on free ion relationships as determined by geochemical equilibrium modeling software (WHAM ver. 7.02). The log K value for Dy{sup 3+} toxicity to Hyalella was 7.75 while the protective influence of Ca and Na were 3.95 and 4.10, respectively. This study contributes data towards the development of site specific

  20. White light emission of dysprosium doped lanthanum calcium phosphate oxide and oxyfluoride glasses

    Science.gov (United States)

    Luewarasirikul, N.; Kim, H. J.; Meejitpaisan, P.; Kaewkhao, J.

    2017-04-01

    Lanthanum calcium phosphate oxide and oxyfluoride glasses doped with dysprosium oxide were prepared by melt-quenching technique with chemical composition 20La2O3:10CaO:69P2O5:1Dy2O3 and 20La2O3:10CaF2:69P2O5:1Dy2O3. The physical, optical and luminescence properties of the glass samples were studied to evaluate their potential to using as luminescence materials for solid-state lighting applications. The density, molar volume and refractive index of the glass samples were carried out. The optical and luminescence properties were studied by investigating absorption, excitation, and emission spectra of the glass samples. The absorption spectra were investigated in the UV-Vis-NIR region from 300 to 2000 nm. The excitation spectra observed under 574 nm emission wavelength showed the highest peak centered at 349 nm (6H15/2 → 6P7/2). The emission spectra, excited with 349 nm excitation wavelength showed two major peaks corresponding to 482 nm blue emission (4F9/2 → 6H15/2) and 574 nm yellow emission (4F9/2 → 6H13/2). The experimental lifetime were found to be 0.539 and 0.540 for oxide and oxyfluoride glass sample, respectively. The x,y color coordinates under 349 nm excitation wavelength were (0.38, 0.43) for both glass samples, that be plotted in white region of CIE 1931 chromaticity diagram. The CCT values obtained from the glass samples are 4204 K for oxide glass and 4228 K for oxyfluoride glass corresponding to the commercial cool white light (3100-4500 K). Judd-Ofelt theory had also been employed to obtain the J-O parameters (Ω2, Ω4 and Ω6), oscillator strength, radiative transition possibility, stimulated emission cross section and branching ratio. The Ω2 > Ω4 > Ω6 trend of J-O parameters of both glass samples may indicate the good quality of a glass host for using as optical device application. Temperature dependence of emission spectra was studied from 300 K to 10 K and found that the intensity of the emission peak was found to be increased with

  1. Full potential calculations and atom in molecule analysis of the bonding properties of perovskites Borides XRh3B (X=Dy, Ho, Er)

    OpenAIRE

    Ouahrani T.; Merad Boudia I.; Lasri B.

    2013-01-01

    ab initio calculations were performed for the cubic perovskites Borides XRh3B, (X=Dy, Ho, Er). In this work, we have used the augmented plane-wave plus local orbital method to compute the equilibrium structural parameters and electronic structure of densities of states, as well as for the first time, prediction of the thermo-elastic properties of these crystals are presented. The chemical bonding of these compounds has been investigated by using of topological analyses grounded in the theory ...

  2. Limits on violations of Lorentz symmetry and the Einstein equivalence principle using radio-frequency spectroscopy of atomic dysprosium.

    Science.gov (United States)

    Hohensee, M A; Leefer, N; Budker, D; Harabati, C; Dzuba, V A; Flambaum, V V

    2013-08-02

    We report a joint test of local Lorentz invariance and the Einstein equivalence principle for electrons, using long-term measurements of the transition frequency between two nearly degenerate states of atomic dysprosium. We present many-body calculations which demonstrate that the energy splitting of these states is particularly sensitive to violations of both special and general relativity. We limit Lorentz violation for electrons at the level of 10(-17), matching or improving the best laboratory and astrophysical limits by up to a factor of 10, and improve bounds on gravitational redshift anomalies for electrons by 2 orders of magnitude, to 10(-8). With some enhancements, our experiment may be sensitive to Lorentz violation at the level of 9 × 10(-20).

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

    Science.gov (United States)

    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.

  4. Processing development of 4 tantalum carbide-hafnium carbide and related carbides and borides for extreme environments

    Science.gov (United States)

    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. Spectroscopic data of the 1.8-, 2.9-, and 4.3- mu m transitions in dysprosium-doped gallium lanthanum sulfide glass

    Science.gov (United States)

    Schweizer, T.; Hewak, D. W.; Samson, B. N.; Payne, D. N.

    1996-10-01

    Infrared emission at 1.8, 2.9, and 4.3 mu m is measured in dysprosium-doped gallium lanthanum sulfide (Ga:La:S) glass excited at 815 nm. Emission cross sections were calculated by Judd-Ofelt analysis, the Fuchtbauer-Ladenburg equation, and the theory of McCumber. The sigma tau value for the 4.3- mu m transition is \\similar 4000 times larger in the Ga:La:S glass than in a dysprosium-doped LiYF4 crystal, which has lased on this transition. The large sigma tau value and the recently reported ability of Ga:La:S glass to be fabricated into fiber form show the potential for an efficient, low-threshold mid-infrared fiber laser. The fluorescence peak at 4.3 mu m coincides with the fundamental absorption of atmospheric carbon dioxide, making the glass a potential laser source for gas-sensing applications.

  6. Spectroscopic data of the 1.8-, 2.9-, and 4.3-microm transitions in dysprosium-doped gallium lanthanum sulfide glass.

    Science.gov (United States)

    Schweizer, T; Hewak, D W; Samson, B N; Payne, D N

    1996-10-01

    Infrared emission at 1.8, 2.9, and 4.3 microm is measured in dysprosium-doped gallium lanthanum sulfide (Ga:La:S) glass excited at 815 nm. Emission cross sections were calculated by Judd-Ofelt analysis, the Füchtbauer- Ladenburg equation, and the theory of McCumber. The sigmatau value for the 4.3-microm transition is ~4000 times larger in the Ga:La:S glass than in a dysprosium-doped LiYF(4) crystal, which has lased on this transition. The large sigmatau value and the recently reported ability of Ga:La:S glass to be fabricated into fiber form show the potential for an efficient, low-threshold mid-infrared fiber laser. The f luorescence peak at 4.3 microm coincides with the fundamental absorption of atmospheric carbon dioxide, making the glass a potential laser source for gas-sensing applications.

  7. On-line complexation/cloud point preconcentration for the sensitive determination of dysprosium in urine by flow injection inductively coupled plasma-optical emission spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Ortega, Claudia; Cerutti, Soledad; Silva, Maria F. [Departamento de Quimica Analitica, Facultad de Quimica, Bioquimica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, 5700, San Luis (Argentina); Olsina, Roberto A.; Martinez, Luis D. [Departamento de Quimica Analitica, Facultad de Quimica, Bioquimica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, 5700, San Luis (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Avda. Rivadavia 1917, CP C1033AAJJ, Buenos Aires (Argentina)

    2003-01-01

    An on-line dysprosium preconcentration and determination system based on the hyphenation of cloud point extraction (CPE) to flow injection analysis (FIA) associated with ICP-OES was studied. For the preconcentration of dysprosium, a Dy(III)-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol complex was formed on-line at pH 9.22 in the presence of nonionic micelles of PONPE-7.5. The micellar system containing the complex was thermostated at 30 C in order to promote phase separation, and the surfactant-rich phase was retained in a microcolumn packed with cotton at pH 9.2. The surfactant-rich phase was eluted with 4 mol L{sup -1} nitric acid at a flow rate of 1.5 mL min{sup -1}, directly in the nebulizer of the plasma. An enhancement factor of 50 was obtained for the preconcentration of 50 mL of sample solution. The detection limit value for the preconcentration of 50 mL of aqueous solution of Dy was 0.03 {mu}g L{sup -1}. The precision for 10 replicate determinations at the 2.0 {mu}g L{sup -1}Dy level was 2.2% relative standard deviation (RSD), calculated from the peak heights obtained. The calibration graph using the preconcentration system for dysprosium was linear with a correlation coefficient of 0.9994 at levels near the detection limits up to at least 100 {mu}g L {sup -1}. The method was successfully applied to the determination of dysprosium in urine. (orig.)

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

    Science.gov (United States)

    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.

  9. Two-phase zirconium boride thin film obtained by ultra-short pulsed laser ablation of a ZrB{sub 12} target

    Energy Technology Data Exchange (ETDEWEB)

    De Bonis, A., E-mail: angela.debonis@unibas.it [Dipartimento di Scienze, Università della Basilicata, Viale dell’Ateneo Lucano, 10 -85100 Potenza (Italy); Istituto di Metodologie Inorganiche e dei Plasmi, Consiglio Nazionale delle Ricerche, U.O.S. di Potenza, C.da Santa Loja, 85010 Tito Scalo, Potenza (Italy); Santagata, A. [Istituto di Metodologie Inorganiche e dei Plasmi, Consiglio Nazionale delle Ricerche, U.O.S. di Potenza, C.da Santa Loja, 85010 Tito Scalo, Potenza (Italy); Rau, J.V. [Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere 100, 00133 Rome (Italy); Latini, A. [Università di Roma “La Sapienza”, Dipartimento di Chimica, Piazzale Aldo Moro, 5 -00185 Rome (Italy); Mori, T. [National Institute for Materials Science (NIMS) WPI Materials Nanoarchitectonics Center (MANA), Namiki 1-1, Tsukuba 305-0044 (Japan); Medici, L. [Istituto di Metodologie per le Analisi Ambientali, Consiglio Nazionale delle Ricerche, U.O.S. di Potenza, C.da Santa Loja, 85010 Tito Scalo, Potenza (Italy); Teghil, R. [Dipartimento di Scienze, Università della Basilicata, Viale dell’Ateneo Lucano, 10 -85100 Potenza (Italy)

    2013-10-15

    Two-phase zirconium boride thin films have been obtained by ultra-short pulsed laser ablation (PLA) of a zirconium dodecaboride (ZrB{sub 12}) target performed in vacuum. The ablation source was a frequency doubled (λ = 527 nm) Nd:glass laser with a pulse duration of 250 fs. Laser induced plasma has been studied by ICCD imaging and time and space resolved optical emission spectroscopy (OES), whereas the deposited films have been characterized by atomic force microscopy, scanning electron microscopy, X-Ray diffraction and micro-Raman spectroscopy. The film morphology and composition have been interpreted on the basis of the laser ablation mechanism.

  10. Synthesis and Crystal Structure of Tri-(2-mercaptopyridine N-oxide)bis(dimethyl sulfoxide) Dysprosium(Ⅲ)

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A range of rare earth metal complexes of 2-mercaptopyridine N-oxide (Hmpo) have been synthesized, and studied by elemental analysis and IR spectroscopic technique. Crystal structure of Dy(mpo)3(DMSO)2 (DMSO = dimethyl sulfoxide) has been determined. The complex crystallizes in the triclinic system, space group Pī with lattice parameters: a = 9.602(3), b = 9.803(3), c = 15.498(5)A, α= 89.51(1), β= 85.73(1), γ= 62.99(1)°, Dc = 1.787 g/cm3, C19H24N3O5S5Dy, Mr = 697.21, Z = 2, F(000) = 690, μ = 3.321mm-1, the final R = 0.0237 and wR = 0.0587 for 4116 reflections with I>σ2(I). The coordination number of dysprosium Ⅲ is eight, and its coordination geometry is a somewhat distorted square antiprism with O(3), O(4), O(5), S(3) and O(1), O(2), S(1), S(2) at the tetragonal bases (dihedral angle between their mean planes is 2.9(1)0). Around the Dy atom, three five-membered ring planes (Dy, O, N, C, S) make the dihedral angles of 74.42, 11.31 and 83.72, respectively.

  11. Photo-, cathodo- and thermoluminescent properties of dysprosium-doped HfO2 films deposited by ultrasonic spray pyrolysis.

    Science.gov (United States)

    Manríquez, R Reynoso; Góngora, J A I Díaz; Guzmán-Mendoza, J; Montalvo, T Rivera; Olguín, J C Guzmán; Ramírez, P V Cerón; García-Hipólito, M; Falcony, C

    2014-09-01

    In this work, the photoluminescent (PL), cathodoluminescent (CL) and thermoluminescent (TL) properties of hafnium oxide films doped with trivalent dysprosium ions are reported. The films were deposited on glass substrates at temperatures ranging from 300 to 600°C, using chlorides as precursor reagents. The surface morphology of films showed a veins shaped microstructure at low deposition temperatures, while at higher temperatures the formation of spherical particles was observed on the surface. X-ray diffraction showed the presence of HfO2 monoclinic phase in the films deposited at temperatures greater than 400°C. The PL and CL spectra of the doped films showed the highest emission band centered at 575nm corresponding to the transitions (4)F9/2→(6)H13/2, which is a characteristic transition of Dy(3+) ion. The greatest emission intensities were observed in samples doped with 1 atomic percent (at%) of DyCl3 in the precursor solution. Regarding the TL behavior, the glow curve of HfO2:Dy(+3) films exhibited spectrum with one broad band centered at about 150°C. The highest intensity TL response was observed on the films deposited at 500°C. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2012-08-01

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

  13. Ferroelectric properties of dysprosium-doped Bi4Ti3O12 thin films crystallized in various atmospheres

    Institute of Scientific and Technical Information of China (English)

    CHENG Chuan-pin; TANG Ming-hua; YE Zhi; ZHOU Yic-hun; ZHENG Xue-jun; ZHONG Xiang-li; HU Zeng-shun

    2006-01-01

    Dysprosium-doped Bi4Ti3O12 (Bi3.4Dy0.6Ti3O12,BDT) ferroelectric thin films were deposited on Pt(111)/Ti/SiO2/Si(111) substrates by chemical solution deposition (CSD) and crystallized in nitrogen,air and oxygen atmospheres,respectively. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to identify the crystal structure,the surface and cross-section morphology of the deposited ferroelectric films. The results show that the crystallization atmosphere has significant effect on determining the crystallization and ferroelectric properties of the BDT films. The film crystallized in nitrogen at a relatively low temperature of 650 ℃,exhibits excellent crystallinity and ferroelectricity with a remanent polarization of 2Pr = 24.9 μC/cm2 and a coercive field of 144.5 kV/cm. While the films annealed in air and oxygen at 650 ℃ do not show good crystallinity and ferroelectricity until they are annealed at 700 ℃. The structure evolution and ferroelectric properties of BDT thin films annealed under different temperatures (600-750 ℃) were also investigated. The crystallinity of the BDT films is improved and the average grain size increases when the annealing temperature increases from 600 ℃ to 750 ℃ at an interval of 50 ℃. However,the polarization of the films is not monotonous function of the annealing temperature.

  14. Effects of (Cr,Fe){sub 2}B borides on hardness in powder-injection-molded product fabricated with Fe-based alloy powders

    Energy Technology Data Exchange (ETDEWEB)

    Do, Jeonghyeon; Jeon, Changwoo; Paul Kim, Choongnyun; Lee, Byeong-Joo [Center for Advanced Aerospace Material, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Lee, Sunghak, E-mail: shlee@postech.ac.kr [Center for Advanced Aerospace Material, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Lee, Eon-Sik [Advanced Metallic Materials Research Department, Research Institute of Industrial Science and Technology, Pohang 790-330 (Korea, Republic of); Shik Yoon, Tae [Bestner Co., 146-8 Sangdaewon-dong, Sungnam 462-121 (Korea, Republic of); Su Shin, Yang [New Growth Technology Strategy Department, POSCO, Seoul 135-777 (Korea, Republic of)

    2012-10-30

    In the present study, a powder injection molding (PIM) product containing (Cr,Fe){sub 2}B borides was fabricated with Fe-based alloy powders, and its microstructure and hardness were investigated in relation with volume fraction of (Cr,Fe){sub 2}B. In the Fe-based alloys designed by the thermodynamic calculation, the volume fractions of (Cr,Fe){sub 2}B increased with increasing (X{sub Cr}+X{sub B}) value, and were well matched with those obtained from the thermodynamic calculation. The hardness of the Fe-based alloys linearly increased with increasing volume fraction of (Cr,Fe){sub 2}B. When Fe-based alloy powders were injection-molded and sintered at 1165 Degree-Sign C, a densified microstructure with almost no pores was obtained. In the sintered microstructure, 56 vol% of (Cr,Fe){sub 2}B borides, together with a few pores (porosity; 0.5%), were relatively homogeneously distributed in the tempered martensite matrix, which resulted in the very high hardness over 600 VHN. Such a high hardness suggested that the present Fe-based alloy powders could be readily adopted for fabricating PIM products or for replacing conventional stainless steel PIM products.

  15. Sensitive search for the temporal variation of the fine structure constant using radio-frequency E1 transitions in atomic dysprosium

    CERN Document Server

    Nguyen, A T; Lamoreaux, S K; Torgerson, J R

    2003-01-01

    It has been proposed that the radio-frequency electric-dipole (E1) transition between two nearly degenerate opposite-parity states in atomic dysprosium should be highly sensitive to possible temporal variation of the fine structure constant ($\\alpha$) [V. A. Dzuba, V. V. Flambaum, and J. K. Webb, Phys. Rev. A {\\bf 59}, 230 (1999)]. We discuss here an experimental realization of the proposed search, which involves monitoring the E1 transition frequency over a period of time using direct frequency counting techniques. We estimate that a statistical sensitivity of $|\\adota| \\sim 10^{-18}$/yr may be achieved and discuss possible systematic effects in such a measurement.

  16. Dysprosium doping induced shape and magnetic anisotropy of Fe3-xDyxO4 (x=0.01-0.1) nanoparticles

    Science.gov (United States)

    Jain, Richa; Luthra, Vandna; Gokhale, Shubha

    2016-09-01

    The effect of dysprosium doping on evolution of structural and magnetic properties of magnetite (Fe3O4) nanoparticles is reported. A standard route of co-precipitation was used for the synthesis of undoped and doped magnetite nanoparticles Fe3-xDyxO4 (x=0.0-0.1). Transmission electron microscopy (TEM) shows formation of round shaped particles with diameter in the range of 8-14 nm for undoped sample. On doping beyond x=0.01, the formation of rod like structures is initiated along with the round shaped particles. The number of rods is found to increase with increasing doping concentration. Magnetic characterization using Vibrating Sample Magnetometer (VSM) revealed doping dependent magnetic properties which can be correlated with the crystallite size as determined from X-ray diffraction (XRD). Enhancement in the saturation magnetization in the initial stages of doping can be explained on the basis of incorporation of Dy3+ ions in the inverse spinel structure at the octahedral site in place of Fe3+ ions. Subsequent decrease in saturation magnetization observed beyond x=0.03 could be attributed to precipitation of excess Dy in form of dysprosium ferrite phase.

  17. The coloring problem in the solid-state metal boride carbide ScB{sub 2}C{sub 2}. A theoretical analysis

    Energy Technology Data Exchange (ETDEWEB)

    Lassoued, Souheila [Universite de Rennes, Ecole Nationale Superieure de Chimie, UMR 6226 CNRS (France). Inst. des Sciences Chimiques; Universite Kasdi Merbah-Ouargla (Algeria). Faculte des Mathematiques et des Sciences de la Matiere; Boucher, Benoit [Universite de Rennes, Ecole Nationale Superieure de Chimie, UMR 6226 CNRS (France). Inst. des Sciences Chimiques; Max-Planck-Institut fuer Chemische Physik Fester Stoffe, Dresden (Germany); Boutarfaia, Ahmed [Universite Kasdi Merbah-Ouargla (Algeria). Faculte des Mathematiques et des Sciences de la Matiere; Gautier, Regis; Halet, Jean-Francois [Universite de Rennes, Ecole Nationale Superieure de Chimie, UMR 6226 CNRS (France). Inst. des Sciences Chimiques

    2016-08-01

    The electronic properties of the layered ternary metal boride carbide ScB{sub 2}C{sub 2}, the structure of which consists of B/C layers made of fused five- and seven-membered rings alternating with scandium sheets, are analyzed. In particular, the respective positions of the B and C atoms (the so-called coloring problem) are tackled using density functional theory, quantum theory of atoms in molecules, and electron localizability indicator calculations. Results reveal that (i) the most stable coloring minimizes the number of B-B and C-C contacts and maximizes the number of boron atoms in the heptagons, (ii) the compound is metallic in character, and (iii) rather important covalent bonding occurs between the metallic sheets and the boron-carbon network.

  18. Full potential calculations and atom in molecule analysis of the bonding properties of perovskites Borides XRh3B (X=Dy, Ho, Er

    Directory of Open Access Journals (Sweden)

    Ouahrani T.

    2013-03-01

    Full Text Available ab initio calculations were performed for the cubic perovskites Borides XRh3B, (X=Dy, Ho, Er. In this work, we have used the augmented plane-wave plus local orbital method to compute the equilibrium structural parameters and electronic structure of densities of states, as well as for the first time, prediction of the thermo-elastic properties of these crystals are presented. The chemical bonding of these compounds has been investigated by using of topological analyses grounded in the theory of atoms in molecules (AIM. All of the electron density critical points in the unit cell were systematically calculated in order to calculate basins interaction of each atoms and give exact classification of the bonding character.

  19. Combustion Front Dynamics in the Combustion Synthesis of Refractory Metal Carbides and Di-borides using Time-Resolved X-ray Diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Wong,J.; Larson, E.; Waide, P.; Frahm, R.

    2006-01-01

    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 {yields} MC; (ii) M + 2B {yields} MB{sub 2}; and (iii) 3M + B{sub 4}C {yields} 2MB{sub 2} + 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{sup -1} (or 100 ms frame{sup -1}) was employed. The combustion reactions were found to complete within 200-400 ms. In contrast to the Ta + C {yields} 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 T{sub ad} are well above the melting points of the respective reactant metals and have a typical combustion front velocity of 5-6 mm s{sup -1}. The Nb and Ta systems have lower T{sub ad}, involving no liquid phase. These are truly solid combustion systems and have a lower combustion front velocity of 1-2 mm s{sup -1}. The current study opens up a new avenue to chemical dynamics and macrokinetic investigations of high-temperature solid-state reactions.

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

    Science.gov (United States)

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

    2016-06-28

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

  1. Another challenge to paramagnetic relaxation theory: a study of paramagnetic proton NMR relaxation in closely related series of pyridine-derivatised dysprosium complexes.

    Science.gov (United States)

    Rogers, Nicola J; Finney, Katie-Louise N A; Senanayake, P Kanthi; Parker, David

    2016-02-14

    Measurements of the relaxation rate behaviour of two series of dysprosium complexes have been performed in solution, over the field range 1.0 to 16.5 Tesla. The field dependence has been modelled using Bloch-Redfield-Wangsness theory, allowing estimates of the electronic relaxation time, T1e, and the size of the magnetic susceptibility, μeff, to be made. Changes in relaxation rate of the order of 50% at higher fields were measured, following variation of the para-substituent in the single pyridine donor. The magnetic susceptibilities deviated unexpectedly from the free-ion values for certain derivatives in each series examined, in a manner that was independent of the electron-releasing/withdrawing ability of the pyridine substituent, suggesting that the polarisability of just one pyridine donor in octadenate ligands can play a significant role in defining the magnetic susceptibility anisotropy.

  2. A Study on the Effect of the Boron Potential on the Mechanical Properties of the Borided Layers Obtained by Boron Diffusion at the Surface of AISI 316L Steel

    Directory of Open Access Journals (Sweden)

    E. Hernández-Sánchez

    2014-01-01

    Full Text Available The effect of the boron potential on the thickness and the mechanical properties of borided layers was evaluated. The boron potential was established by means of the available atoms of boron contained in a control volume inside a cylinder. The cylinders were manufactured from AISI 316L steel, and the boriding treatment was performed using the powder pack technique at a temperature of 1273 K over an exposure time of 6 h. Four different internal diameters of the cylinders were evaluated (3.17, 4.76, 6.35, and 7.93 mm. The mechanical properties were evaluated using the Berkovich instrumented indentation technique. The results showed a clear influence of the boron potential on the mechanical properties of the layers. The hardness of the layers was stablished in the range of 16.22 to 21.16 GPa. Young’s modulus values were stablished in the range of 255.96 to 341.37 GPa. Also the fracture toughness and brittleness of the layers reflected the influence of the boron potential supplied during the boriding process. Finally, the influence of the boron potential on the constant of parabolic growth (K was also established as a function of the inner diameter of the cylinders.

  3. 硼化物陶瓷基涂层制备技术的研究进展%Research Progress of Preparation Technology on the Boride Ceramic-based Coating

    Institute of Scientific and Technical Information of China (English)

    贾成科; 张鑫; 任先京; 冀晓鹃; 彭浩然

    2012-01-01

    Boride cermet is a new cermet with many excellent properties such as high melting temperature, bulk hardness, high chemical stability, high wearable property, and good anti-causticity, which is used in the fields such as fire-resistant material, engineering cermet, nuclear industry, and space navigation. The same excellent properties of the boride ceramic based coating prepared by many kinds of techniques, which are play important roles in many fields such as ultra high-temperature components, high wearable property units,good anti-causticity parts, anti-liquid metal-causticity component, and neutron-ratiant guard etc. The preparation methods of the boride ceramic- based coating with the strongpoint and disadvantage are introduced. The advances and the application of boride ceramic- based coating, mostly including duality boride ceramic based coatings and ternary ones, are also summarized as well as the existing problems and the prospects are analyzed.%硼化物陶瓷是一种新型陶瓷材料,具有诸如高熔点、高硬度、高化学稳定性以及高耐磨、抗腐蚀性等优异的综合性能,在耐火材料、工程陶瓷、核工业、宇航等领域有着广泛应用,而通过多种工艺制备的硼化物陶瓷基涂层同样具有很好的性质和功能,这些优异的特性使得目前硼化物涂层在很多工程领域发挥着极其重要的作用,如超高温部件、高耐磨蚀性部件以及抗金属液腐蚀性的部件、中子辐射防护装置等。本文介绍了硼化物陶瓷基涂层的制备方法,指出了各种方法的优缺点,综述了硼化物陶瓷基涂层的研究进展及其涂层的应用情况,主要包括二元硼化物陶瓷基涂层、多元硼化物基金属涂层等,总结了目前该领域存在的问题,并对今后的发展前景进行了展望。

  4. 合金球墨铸铁的渗硼动力学研究%Study of Boriding Kinetics for Alloyed Ductile Irons

    Institute of Scientific and Technical Information of China (English)

    Fábio Edson Mariani; Galtiere Correa Rego; Luiz Carlos Casteletti; Amadeu Lombardi Neto; George Edward Totten3

    2016-01-01

    Boriding thermochemical treatment produces layers with high hardness which improves the tribological performance of ductile cast iron while the austempering treatment improves the mechanical performance of the substrate.In this work,samples of the ductile cast iron alloyed with copper,copper-nickel and copper-nickel-molybdenum were borided in a salt bath (borax +aluminum)at temperatures of 850,900 and 950 ℃ during 2 and 4 hours.The data for the layers obtained were used to determine the diffusion coefficients and activation energies of this process.The results of the calculated diffusion coefficients were similar to those obtained by the direct measurements of the layer thicknesses.For the sample alloyed with Cu or Cu-Ni the activation energy obtained was 141.27 kJ/mol,and for the sample alloyed with Cu-Ni-Mo the value was 212.98 kJ/mol.The statistical parameters and the correlation coefficients (R)showed satisfactory agreement.%渗硼层硬度高,能改善球墨铸铁(以下简称球铁)的摩擦学性能,而等温淬火能提高基体的力学性能。对含Cu、Cu-Ni和Cu-Ni-Mo的合金球铁试样进行了盐浴(硼砂+铝)渗硼,渗硼温度分别为850℃、900℃和950℃,时间2 h和4 h。通过所获得的渗层数据确定合金球铁渗硼的扩散系数和激活能。计算求得的扩散系数与通过直接测定渗层厚度得出的扩散系数相接近。含Cu或Cu-Ni的试样激活能为141.27 kJ/mol,而含Cu-Ni-Mo的试样激活能为212.98 kJ/mol。统计参数与相关系数(R)吻合良好。

  5. 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

    Science.gov (United States)

    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.

  6. Study of Transport and Micro-structural properties of Magnesium Di-Boride Strand under react and bend mode and bend and react mode

    Science.gov (United States)

    Kundu, Ananya; Das, Subrat Kumar; Bano, Anees; Pradhan, Subrata

    2017-04-01

    I-V characterization of commercial multi-filamentary Magnesium Di-Boride (MgB2) wire of diameter 0.83 mm were studied in Cryocooler at self-field I-V characterization system under both react and bend mode and bend and react mode for a range of temperature 6 K - 25 K. This study is of practical technical relevance where the heat treatment of the superconducting wire makes the wire less flexible for winding in magnet and in other applications. In the present work the bending diameter was varied from 40 mm to 20 mm and for each case critical current (Ic) of the strand is measured for above range of temperature. A customized sample holder is fabricated and thermally anchored with the 2nd cold stage of Cryocooler. It is observed from the measurement that the strand is more susceptible to degradation for react and bend cases. The transport measurement of the strand was accompanied by SEM analyses of bend samples. Also the tensile strength of the raw strands and the heat treated strands were carried out at room temperature in Universal Testing Machine (UTM) to have an estimate about the limiting winding tension value during magnet fabrication.

  7. Sliding wear characteristics of Co-based overlay weld metal with dispersed boride particles; Hokabutsu ryushi bunsan kyoka Co ki nikumori kinzoku no suberi mamosei

    Energy Technology Data Exchange (ETDEWEB)

    Nishida, M.; Araki, T.; Shigekawa, Y. [Ehime University, Ehime (Japan). Faculty of Engineering; Asano, I.; Hayashi, Y. [Sumitomo Heavy Industries, Ltd., Tokyo (Japan)

    1998-05-05

    Requirements on wear resistant materials in recent years are applied not only to strength and hardness, but also to heat resistance and corrosion resistance. This paper describes fabrication of an overlay weld metal reinforced by dispersed particles, structured by a Co-based alloy (stellite No. 6) added with boride (MoB powder) using a plasma transferred arc welding process. The paper discusses the effect of MoB on wear characteristics at room temperature and elevated temperatures, as well as on seizability. When the MoB addition amount is increased to 3% by mass or more, the structure was found constituted by an eutectic structure with M2B and {beta} phases and an eutectic structure with M23C6 and {beta} phases, in addition to plate-shaped crystallized substance of CoMo2B2 which is a tetragonal system, and a matrix of {beta} Co. When S45C is used as a counterpart material, wear resistance was improved regardless of temperatures by making hardness of the overlay metal higher by HV 300 or more than that of the counterpart material. The overlay weld metal added with MoB showed high friction coefficient at room temperature, but even if the temperature is raised, it had less agglutination of S45C, and decreased at elevated temperatures. 13 refs., 16 figs., 1 tab.

  8. 硼化锆基超高温陶瓷研究进展%Development of zirconium boride based ultrahigh temperature ceramics

    Institute of Scientific and Technical Information of China (English)

    邓晓军; 谢征芳

    2012-01-01

    航空航天、兵器、能源等高科技领域的发展对轻质、耐高温的超高温陶瓷材料提出了迫切需求.硼化锆基超高温陶瓷是最重要的超高温陶瓷材料之一,综述了硼化锆基超高温陶瓷的研究进展,着重探讨了先驱体转化法制备硼化锆基超高温陶瓷的优势和难点,并对硼化锆基超高温陶瓷的发展进行了展望.%With the development of aerospace,weapons,and energy,ultrahigh temperature ceramics (UHTCs) are urgently required. Zirconium boride ( ZrB2 ) ceramics, one of the most important UHTCs, has received considerable attention due to its excellent high temperature resistance. The developments of ZrB2 -based ceramics are reviewed in the paper. The advantages, as well as the difficulties of ZrB2 -based ceramics by polymer-derived technique are discussed. The future development of ZrB2 -based ceramics is also prospected.

  9. Tuning the composition and magnetostructure of dysprosium iron garnets by Co-substitution: An XRD, FT-IR, XPS and VSM study

    Energy Technology Data Exchange (ETDEWEB)

    Tholkappiyan, R.; Vishista, K., E-mail: raovishista@gmail.com

    2015-10-01

    Graphical abstract: - Highlights: • Garnet type Dy{sub 3}Fe{sub 5−x}Co{sub x}O{sub 12} (x = 0–0.06) nanoparticles were synthesized by glycine assisted combustion method. • To investigate and confirm the phases in the synthesized ferrite nanoparticles by FT-IR and XRD analysis. • To investigate the compositional and oxidation state of the samples by X-ray photoelectron spectroscopy. • The detailed core level spectra of Dy 4d, Fe 2p, Co 2p and O 1s were analyzed using XPS. • The magnetic property was studied by VSM technique. - Abstract: We report the Co-substituting on the synthesis and properties of garnet type dysprosium ferrite nanoparticles by basic composition Dy{sub 3}Fe{sub 5−x}Co{sub x}O{sub 12} (x = 0–0.06) synthesized through glycine assisted combustion method. A possible formation mechanism of synthesized Dy{sub 3}Fe{sub 5−x}Co{sub x}O{sub 12} samples by controlling the synthesis process has been proposed. XRD, FT-IR, XPS and VSM studies were used to investigate the compositional and magnetostructural properties of the prepared nanoparticles. XRD results confirm that all the samples are single-phase cubic garnet structure with mean crystallite size of 97–105 nm obtained from Scherrer method and 95–102 nm from W–H method. FT-IR analysis shows the presence of three expected bands in the frequency limit of 450–600 cm{sup −1} attributed to metal–O stretching vibration in tetrahedral site of garnet structure. A typical survey spectrum from XPS results confirmed the presence of Dy, Fe, Co and O elements in the samples. This study also to characterize the different oxidation states of the samples by fitting the parameters of high resolution Dy 4d, Fe 2p, Co 2p and O 1s XPS spectra. The XPS data of Dy 4d spectrum show that Dy{sup 3+} ion occupy in dodecahedral (D) site. The XPS analysis of Fe 2p and Co 2p data suggests that (Fe{sup 3+} and Fe{sup 2+}), (Co{sup 3+} and Co{sup 2+}) are distributed in tetrahedral and octahedral sites

  10. Comportamiento parabólico del crecimiento de capas boradas en los aceros Y8A y X12M // Parabolic behavior of boriding layers growth in Y8A and X12M steels

    Directory of Open Access Journals (Sweden)

    C. Figueroa Hernández

    1999-01-01

    Full Text Available Se determina la influencia que tienen los principales parámetros tecnológicos del borado en el crecimiento de las capas y secorrobora el cumplimiento de la ley parabólica para predecir este comportamiento en los aceros Y8A y X12M.El proceso de borado se aplica en una mezcla de carburo de silicio y bórax (70 y 30 % a la temperatura de 850, 900 y 950 oCdurante un tiempo de 2, 4 y 6 horas. Como variable dependiente se seleccionó la profundidad del recubrimiento, a partir de lacual se obtuvieron los coeficientes del crecimiento parabólico y la energía de activación en función de la temperatura, el tiempodel proceso y el tipo de acero.La caracterización metalográfica reveló la presencia de la fase Fe2BPalabras claves: Borado, recubrimiento superf icial , t ecnología de recubrimiento.__________________________________________________________________________AbstractIt was determined the influence of the main technological parameters of the boriding process, and a mathematical model thatallows to predict this conduct on the steels Y8A and X12M steels was obtained.The boriding process is applied in a mixture of silicon carbide and borax (70 and 30% at 850, 900 and 950 oC temperatureduring a period of time 2, 4 and 6 hours. As an independent variable the depth of the coat was selected.It was obtained the parabolic growth coefficients, and the activation energy according to temperature, time and the chemicalcomposition of steel.Metallografic analysis reveals the presence of Fe2B phase.Key words: Boriding process, superf icial coat , coat technology.

  11. Caracterización de la capa de boruros formada durante la austenización de un hierro nodular austemperizado//Characterization of borides coating formed during austenitization of an austempered ductile iron

    Directory of Open Access Journals (Sweden)

    Urbano Ordóñez‐Hernández

    2015-01-01

    Full Text Available En este trabajo se ha investigado el efecto de la austenitización y el borurado simultáneos, a 950 ºC, en la microestructura, la microdureza Vickers y el espesor de la capa borurada en medio líquido de un hierro nodular austemperizado no aleado. Se demostró que es posible obtener una capa de boruros de hierro muy bien estructurada con la microdureza Vickers suficientemente alta (1400 HVy con adecuado espesor de capa de 67 μm, sobre un sustrato de ausferrita típico de las fundiciones nodulares austemperizadas. Por medio de un ensayo pin on disc modificado, se comprobó la superior resistencia al desgaste abrasivo de la capa de boruros depositada durante la austenización del ADI, comparada con la máxima obtenida durante el austempering de éste sin aplicar el recubrimiento.Palabras claves: hierro nodular, borurado, austenización, austemperizado.______________________________________________________________________________AbstractThe effect of simultaneous austenitization and boriding at 950 ºC, on microstructure, Vickers hardness and boronized layer thickness of a non alloyed austempered ductile iron has been investigated. It was demonstrated that it is possible to obtain a well formed boronized layer with a Vicker hardness sufficiently high (1400 HV, and with an appropriated 67μm layer thickness, on a typical ausferrite ADI substrate. By using a modified pin on disc test, it was demonstrated the higher abrasion wear resistance of borides layer deposited during ADI austenitization process, compared with Vickers hardness of low temperature noncoated austempered ductile iron.Key words: ductile iron, boriding, austenitization, austempering.

  12. A dysprosium-based metal-organic framework: Synthesis, characterization, crystal structure and interaction with calf thymus-DNA and bovine serum albumin

    Indian Academy of Sciences (India)

    Biplab Mondal; Buddhadeb Sen; Ennio Zangrando; Pabitra Chattopadhyay

    2014-07-01

    A dysprosium-based metallo-organic framework (MOF) containing calcium ions formulated as {Dy(pyda)3Ca1.5(H2O)6} · 5.5H2O (1) (H2pyda = pyridine-2,6-dicarboxylic acid) was solvothermally synthesized in ethanolic medium and characterized by physico-chemical and spectroscopic tools. A detailed structural analysis of the solid state structure of 1 by single crystal X-ray diffraction study showed a tricapped trigonal prism geometry for lanthanide in the [Dy(pyda)3]3− fragment. The mode of interaction of 1 with calf thymus- DNA and with protein bovine serum albumin (BSA) was investigated by using absorption and emission spectroscopic tools. The apparent association constant of complex 1 with CT-DNA was deduced from an absorption spectral study (b = 4.08 × 104 M-1). Spectral and viscosity measurements indicated a groove-binding mode of 1 with CT-DNA, and from spectroscopic study the formation of a metal complex-BSA adduct was assumed to be the result of the interaction of 1 with BSA.

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

    Science.gov (United States)

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

    2015-09-01

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

  14. Experimental and molecular dynamics studies of dysprosium(III) salt solutions for a better representation of the microscopic features used within the binding mean spherical approximation theory.

    Science.gov (United States)

    Ruas, Alexandre; Guilbaud, Philippe; Den Auwer, Christophe; Moulin, Christophe; Simonin, Jean-Pierre; Turq, Pierre; Moisy, Philippe

    2006-10-19

    This work is aimed at a predictive description of the thermodynamic properties of actinide(III) salt solutions at high concentration and 25 degrees C. A new solution of the binding mean spherical approximation (BIMSA) theory, based on the Wertheim formalism, for taking into account 1:1 and also 1:2 complex formation, is used to reproduce, from a simple procedure, experimental osmotic coefficient variation with concentration for three binary salt solutions of the same lanthanide(III) cation: dysprosium(III) perchlorate, nitrate, and chloride. The relevance of the fitted parameters is discussed, and their values are compared with available literature values. UV-vis/near-IR, time-resolved laser-induced fluorescence spectroscopy experiments, and molecular dynamics (MD) calculations were conducted for dilute to concentrated solutions (ca. 3 mol.kg-1) for a study of the microscopic behavior of DyCl3 binary solutions. Coupling MD calculations and extended X-ray absorption fine structure led to the determination of reliable distances. The MD results were used for a discussion of the parameters used in the BIMSA.

  15. Experimental and molecular dynamics studies of dysprosium(III) salt solutions for a better representation of the microscopic features used within the binding mean spherical approximation theory

    Energy Technology Data Exchange (ETDEWEB)

    Ruas, Alexandre; Guilbaud, Philippe; Den Auwer, Christophe; Moulin, Christophe; Simonin, Jean-Pierre; Turq, Pierre; Moisy, Philippe [DEN/DRCP/SCPS, CEA-Valrho Marcoule, BP 17171, 30207 Bagnols-sur-Ceze Cedex, DEN/DPC/SECR/LSRM, CEA-Saclay, Bat 391, BP 91191 Gif sur Yvette, Cedex (France); Laboratoire LI2C (UMR 7612), Universite Pierre et Marie Curie-Paris 6, Boite No. 51, 4 Place Jussieu, 75252 Paris Cedex 05 (France)

    2006-07-01

    This work is aimed at a predictive description of the thermodynamic properties of actinide (III) salt solutions at high concentration and 25 deg. C. A new solution of the binding mean spherical approximation (BIMSA) theory, based on the Wertheim formalism, for taking into account 1: 1 and also 1: 2 complex formation, is used to reproduce, from a simple procedure, experimental osmotic coefficient variation with concentration for three binary salt solutions of the same lanthanide (III) cation: dysprosium (III) perchlorate, nitrate, and chloride. The relevance of the fitted parameters is discussed, and their values are compared with available literature values. UV-vis/near-IR, time-resolved laser-induced fluorescence spectroscopy experiments, and molecular dynamics (MD) calculations were conducted for dilute to concentrated solutions (ca. 3 mol, kg{sup -1}) for a study of the microscopic behavior of DyCl{sub 3} binary solutions. Coupling MD calculations and extended X-ray absorption fine structure led to the determination of reliable distances. The MD results were used for a discussion of the parameters used in the BIMSA. (authors)

  16. Elucidation of Dual Magnetic Relaxation Processes in Dinuclear Dysprosium(III) Phthalocyaninato Triple-Decker Single-Molecule Magnets Depending on the Octacoordination Geometry.

    Science.gov (United States)

    Katoh, Keiichi; Aizawa, Yu; Morita, Takaumi; Breedlove, Brian K; Yamashita, Masahiro

    2017-08-07

    When applying single-molecule magnets (SMMs) to spintronic devices, control of the quantum tunneling of the magnetization (QTM) as well as a spin-lattice interactions are important. Attempts have been made to use not only coordination geometry but also magnetic interactions between SMMs as an exchange bias. In this manuscript, dinuclear dysprosium(III) (Dy(III) ) SMMs with the same octacoordination geometry undergo dual magnetic relaxation processes at low temperature. In the dinuclear Dy(III) phthalocyaninato (Pc(2-) ) triple-decker type complex [(Pc)Dy(ooPc)Dy(Pc)] (1) (ooPc(2-) =2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyaninato) with a square-antiprismatic (SAP) geometry, the ground state is divided by the Zeeman effect, and level intersection occurs when a magnetic field is applied. Due to the ground state properties of 1, since the Zeeman diagram where the levels intersect in an Hdc of 2500 Oe, two kinds of QTM and direct processes occur. However, dinuclear Dy(III) -Pc systems with C4 geometry, which have a twist angle (ϕ) of less than 45° do not undergo dual magnetic relaxation processes. From magnetic field and temperature dependences, the dual magnetic relaxation processes were clarified. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Annealing behaviour and crystal structure of RF-sputtered Bi-substituted dysprosium iron-garnet films having excess co-sputtered Bi-oxide content

    Energy Technology Data Exchange (ETDEWEB)

    Vasiliev, M; Nur-E-Alam, M; Alameh, K [Electron Science Research Institute, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA, 6027 (Australia); Premchander, P; Lee, Y T [Department of Information and Communications, Gwangju Institute of Science and Technology (GIST), Gwangju, 500-712 (Korea, Republic of); Kotov, V A [Institute of Radio Engineering and Electronics, Russian Academy of Sciences, 11 Mohovaya St, Moscow, 125009 (Russian Federation); Lee, Y P, E-mail: m.vasiliev@ecu.edu.au [Quantum Photonic Science Research Center, Department of Physics, Hanyang University, 133-791 (Korea, Republic of)

    2011-02-23

    We investigate the magneto-optic properties, crystal structure and annealing behaviour of nano-composite media with record-high magneto-optic quality exceeding the levels reported so far in sputtered iron-garnet films. Bi-substituted dysprosium-gallium iron-garnet films having excess bismuth oxide content are deposited using RF co-sputtering, and a range of garnet materials are crystallized using conventional oven-annealing processes. We report, for the first time ever, the results of optimization of thermal processing regimes for various high-performance magneto-optic iron-garnet compositions synthesized and describe the evolution of the optical and magneto-optical properties of garnet-Bi-oxide composite-material films occurring during the annealing processes. The crystallization temperature boundaries of the system (BiDy){sub 3}(FeGa){sub 5}O{sub 12} : Bi{sub 2}O{sub 3} are presented. We also report the results of x-ray diffraction and energy-dispersive x-ray spectroscopy studies of this recently developed class of high-performance magneto-optic composites. Our hypothesis of iron oxides being the cause of excess optical absorption in sputtered Bi-iron-garnet films is confirmed experimentally.

  18. 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, ...

    Science.gov (United States)

    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)

  19. 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

    Energy Technology Data Exchange (ETDEWEB)

    Bykova, E., E-mail: elena.bykova@uni-bayreuth.de [Bavarian Research Institute of Experimental Geochemistry and Geophysics, University of Bayreuth, D-95440 Bayreuth (Germany); Laboratory of Crystallography, University of Bayreuth, D-95440 Bayreuth (Germany); Gou, H.; Bykov, M. [Laboratory of Crystallography, University of Bayreuth, D-95440 Bayreuth (Germany); Hanfland, M. [European Synchrotron Radiation Facility, BP 220, Grenoble F-38043 (France); Dubrovinsky, L. [Bavarian Research Institute of Experimental Geochemistry and Geophysics, University of Bayreuth, D-95440 Bayreuth (Germany); Dubrovinskaia, N. [Laboratory of Crystallography, University of Bayreuth, D-95440 Bayreuth (Germany)

    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.

  20. Synthesis and characterization of new metal-rich borides with boron fragments; Synthese und Charakterisierung von neuartigen metallreichen Boriden mit Borfragmenten

    Energy Technology Data Exchange (ETDEWEB)

    Mbarki, Mohammed

    2016-03-30

    The present dissertation deals with the synthesis and characterization of new metal-rich borides of the Ce{sub 7}Ni{sub 5±x}Ge{sub 3±x}In{sub 6{sup -}}, Nb{sub 2}OsB{sub 2{sup -}} and NbRuB-type.The samples are synthesized by a solid state reaction route from elements using an electric arc furnace. The structural characterization of the compounds was carried out by using X-ray diffraction methods on powder samples and single crystals. The chemical composition of single-crystals was verified by EDX analyses. Moreover, the magnetic properties of suitable samples were investigated by SQUID magnetometry.The crystal structure of compounds with the nominal composition NbFe{sub 1-x}Ir{sub 6+x}B{sub 8} is successfully solved from single crystal X-ray data. The most prominent feature in this structure are one-dimensional chains along the c-axis formed by the magnetically active element iron on a site of mixed occupation with Iridium (Fe: Ir = 0.77 (2) 0.23 (2)). Thermomagnetic investigations reveal, that ferromagnetic ordering is observed below the Curie temperature (TC) of 350 K. Theoretical investigations suggest that the iron-chains are mainly responsible for the ferromagnetic ordering. In addition, the magnetocaloric effect (MCE) is calculated using isothermal magnetization measurements at several temperatures. The maximal magnetic entropy change ΔS = 0.032 J kg{sup -1} K{sup -1} is observed in the vicinity of T{sub C}. For the phases Nb{sub 6}Mn{sub 0,75(2)}Ir{sub 6,25(2)}B{sub 8} and Nb{sub 6}Co{sub 1,09(2)}Ir{sub 5,91(2)}B{sub 8} a relationship between the measured ferrimagnetic ordering and the crystal structure is found. Tiny superstructure reflections measured by Selected Area Electron Diffraction (SEAD) indicate a different crystal system for those compounds, which allows a ferrimagnetic spin arrangement within this crystal structure.In the second part of the thesis new results about the Nb{sub 2}OsB{sub 2-} and NbRuB-type borides are presented, which both

  1. Synthesis, characterization and thermoelectric properties of metal borides, boron carbides and carbaborides; Synthese, Charakterisierung und thermoelektrische Eigenschaften ausgewaehlter Metallboride, Borcarbide und Carbaboride

    Energy Technology Data Exchange (ETDEWEB)

    Guersoy, Murat

    2015-07-06

    This work reports on the solid state synthesis and structural and thermoelectrical characterization of hexaborides (CaB{sub 6}, SrB{sub 6}, BaB{sub 6}, EuB{sub 6}), diboride dicarbides (CeB{sub 2}C{sub 2}, LaB{sub 2}C{sub 2}), a carbaboride (NaB{sub 5}C) and composites of boron carbide. The characterization was performed by X-ray diffraction methods and Rietveld refinements based on structure models from literature. Most of the compounds were densified by spark plasma sintering at 100 MPa. As high-temperature thermoelectric properties the Seebeck coefficients, electrical conductivities, thermal diffusivities and heat capacities were measured between room temperature and 1073 K. ZT values as high as 0.5 at 1273 K were obtained for n-type conducting EuB{sub 6}. High-temperature X-ray diffraction also confirmed its thermal stability. The solid solutions Ca{sub x}Sr{sub 1-x}B{sub 6}, Ca{sub x}Ba{sub 1-x}B{sub 6} and Sr{sub x}Ba{sub 1-x}B{sub 6} (x = 0, 0.25, 0.5, 0.75, 1) are also n-type but did not show better ZT values for the ternary compounds compared to the binaries, but for CaB{sub 6} the values of the figure of merit (ca. 0.3 at 1073 K) were significantly increased (ca. 50 %) compared to earlier investigations which is attributed to the densification process. Sodium carbaboride, NaB{sub 5}C, was found to be the first p-type thermoelectric material that crystallizes with the hexaboride-structure type. Seebeck coefficients of ca. 80 μV . K{sup -1} were obtained. Cerium diboride dicarbide, CeB{sub 2}C{sub 2}, and lanthanum diboride dicarbide, LaB{sub 2}C{sub 2}, are metallic. Both compounds were used as model compounds to develop compacting strategies for such layered borides. Densities obtained at 50 MPa were determined to be higher than 90 %. A new synthesis route using single source precursors that contain boron and carbon was developed to open the access to new metal-doped boron carbides. It was possible to obtain boron carbide, but metal-doping could not be

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

    Science.gov (United States)

    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.

  3. Global use structures of the magnetic materials neodymium and dysprosium. A scenario-based analysis of the effect of the diffusion of electromobility on the demand for rare earths; Globale Verwendungsstrukturen der Magnetwerkstoffe Neodym und Dysprosium. Eine szenariobasierte Analyse der Auswirkung der Diffusion der Elektromobilitaet auf den Bedarf an Seltenen Erden

    Energy Technology Data Exchange (ETDEWEB)

    Gloeser-Chahoud, Simon; Kuehn, Andre; Tercero Espinoza, Luis

    2016-06-15

    Neodymium-iron-boron magnets (NdFeB) have experienced a significant demand as the most powerful permanent magnet in recent years, especially for the manufacture of compact electric servomotors with high efficiency and high power density, especially for mobile applications in hybrid traction motors and electric vehicles or for electric bikes. However, NdFeB magnets are also increasingly being used in general mechanical engineering (conveying and pumping systems, tools, air conditioning systems, lift motors, etc.), in the small electric motors of conventional passenger cars or in the generators of large wind power plants with permanent magnetic direct drive. Nevertheless, there is still high uncertainty in the use structures of NdFeB magnets and the contained rare earth elements neodymium and dysprosium. An effective instrument for increasing the market transparency and the understanding of complex anthropogenic material cycles is the dynamic material flow modeling. In the present work paper, this instrument is used for an in-depth analysis of the use structures of NdFeB magnets and the contained rare earths on a global scale. The dynamic modeling of product usage cycles reveals today's usage structures and quantifies future magnetic quantities in obsolete product flows. It could be shown that the magnets in today's scrap volume are mainly contained in obsolete electronics applications such as hard disks (HDD), CD and DVD drives, which makes the recycling hardly seem to be economical due to the small magnets and the high material spread, but in the foreseeable future with larger magnetic quantities from synchronous servomotors and generators can be expected, which significantly increases the recycling potential. In a further step, the effect of the diffusion of alternative drives in the automotive market on the dysprosium requirement is analyzed using a system dynamics model and possible adaptation mechanisms in the form of different substitution effects in

  4. The role of dysprosium on the structural and magnetic properties of (Nd1-xDyx)2Fe14B nanoparticles

    Science.gov (United States)

    Rahimi, Hamed; Ghasemi, Ali; Mozaffarinia, Reza; Tavoosi, Majid

    2017-02-01

    In current work, Nd2Fe14B nanoparticles was synthesized by sol-gel method. Dysprosium powders were added into Nd2Fe14B nanoparticles by mechanical alloying process in order to enhancement of coercivity. The phase analysis, structure, and magnetic properties of annealed (Nd1-xDyx)2Fe14B nanoparticles with different Dy-content (x=0.1, 0.2, 0.3, 0.4, 0.5, 0.6) were investigated by employing X-ray diffraction, X-ray photoelectron spectroscopy, energy dispersive spectroscopy, field emission scanning electron microscope, transmission electron microscope and vibrating sample magnetometer techniques. The results showed that with an increase in Dy amounts, the coercivity of particles increased from 2.9 kOe to 13.4 kOe and then decreased to 5.6 kOe. By adding an optimum amount of Dy (x=0.4), the coercivity was significantly increased from 2.9 kOe to 13.4 kOe. The average particle size of annealed (Nd1-xDyx)2Fe14B nanoparticles was below 10 nm. Magnetization reversal studies indicate that the coercivity of milled and annealed (Nd1-xDyx)2Fe14B nanoparticles is controlled by the nucleation of reversed magnetic domains. The experimental results in the angular dependence of coercivity for (Nd1-xDyx)2Fe14B permanent magnets showed that the normalized coercivity of the permanent magnets Hc(θ)/Hc(0) increases from 1 to about 1.2-1.5 with increasing θ from 0 to about π/3, for x=0.4-0.6.

  5. Dysprosium(III) complexes with a square-antiprism configuration featuring mononuclear single-molecule magnetic behaviours based on different β-diketonate ligands and auxiliary ligands.

    Science.gov (United States)

    Zhang, Sheng; Ke, Hongshan; Shi, Quan; Zhang, Jangwei; Yang, Qi; Wei, Qing; Xie, Gang; Wang, Wenyuan; Yang, Desuo; Chen, Sanping

    2016-03-28

    Three mononuclear dysprosium(III) complexes derived from three β-diketonate ligands, 4,4,4-trifluoro-1-(4-methylphenyl)-1,3-butanedione (tfmb), 4,4,4-trifluoro-1-(4-fluorophenyl)-1,3-butanedione (tffb) and 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione (tfnb) as well as auxiliary ligands, 5-nitro-1,10-phenanthroline (5-NO2-Phen), DMF and 2,2'-bipyridine (bpy) have been synthesized and structurally characterized, namely [Dy(5-NO2-Phen)(tfmb)3] (1), [Dy(DMF)2(tffb)3] (2) and [Dy(bpy)2(tfnb)3]·0.5(1,4-dioxane) (3). The metal ions in 1-3 adopt an approximately square-antiprismatic (SAP) coordination environment with D4d axial symmetry. The magnetic properties of 1-3 have been investigated, displaying weak out-of-phase AC signals under a zero-DC field. With an applied DC field of 1200 Oe, the quantum tunnelling of the magnetization was suppressed in 1-3 with the pre-exponential factor τ0 = 5.3 × 10(-7) s and the effective barrier ΔE/kB = 83 K for 1 as well as the pre-exponential factor τ0 = 3.09 × 10(-7) s and the effective barrier ΔE/kB = 39 K for 3. Interestingly, for the frequency dependence of the out-of-phase (χ'') of the AC susceptibility of 2, two slow relaxation of the magnetization processes occurred under the applied magnetic field of 1200 Oe, corresponding to the fast relaxation (FR) phase and slow relaxation (SR) phase, respectively. Arrhenius analysis gave the effective energy barrier (ΔE/kB) of 55 K and the pre-exponential factor (τ0) of 8.23 × 10(-12) for the SR. It is thus very likely that the FR process in complex 2 results from QTM enhanced by dipolar interactions between the Dy ions or the presence of the applied field. The structure-property relationship of some Dy(III) based mononuclear SMMs with the SAP configuration was further discussed.

  6. Magnetic Phase Transition of Nanocrystalline Bulk Metal Gadolinium and Dysprosium%纳米块体金属钆和镝的磁性相变分析

    Institute of Scientific and Technical Information of China (English)

    刘凤艳; 侯碧辉; 岳明; 王克军

    2011-01-01

    The magnetic properties of bulk nanocrystalline metal gadolinium (Gd) and dysprosium (Dy)samples were studied.The magnetization and Curie temperature TC of nanocrystalline Gd and Dy decreased usually as compared with the polycrystal.However,when the mean grain size was 10 nm, the Curie temperature Tc of nanocrystalline Dy increased to 100 K instead and there was an antiferromagnetic phase in nanocrystalline Gd.According to the calculation based on Ruderman-Kittel-Kasuya-Yosida exchange interaction, the exchange integral of the grain boundary atoms and crystalline surface atoms had its sign changed from plus to minus or vice versa, and there were three orderly phases in the steady state with the lowest energy, ferromagnetic phase, antiferromagnetic phase and fan phase.For the nanocrystals with mean grain size of 10 nm, the proportion of grain boundary to crystalline surface atoms was high, and as the result of superposition of the three phases, and there appeared a peak near the phase transition temperature for the nanocrystalline Gd.While for the Dy, the magnetization decreased gently with temperature, and showing a higher Curie temperature than in the case of the polycrystal.%对纳米晶钆(Gd)和镝(Dy)块体材料的磁性进行了研究.与多晶比较,通常纳米晶的磁化强度减小,居里温度TC降低,但平均粒径为10 nm的纳米晶Dy的居里温度TC反而升高到100 K,平均粒径为10 nm的纳米晶Gd中还存在明显的反铁磁相.通过RKKY交换作用的计算知道,晶面晶界处原子的交换积分会发生正负号的变化,能量最低的稳定状态对应三种有序相:铁磁相、反铁磁相和扇相,晶粒中在一定条件下出现三相共存.对于平均粒径为10 nm的纳米晶,晶面晶界处原子所占比例很大,三相叠加的结果,对于Gd,即是在相变点附近出现磁化强度尖峰;对于Dy,则是磁化强度随温度升高下降缓慢,表现为居里温度TC比多晶升高.

  7. Microstructure and wear resistance of Fe -based hardfacing alloys reinforced by borides%硼化物强化铁基堆焊合金显微组织与耐磨性

    Institute of Scientific and Technical Information of China (English)

    宗琳; 宁建荣

    2012-01-01

    为了提高在严峻工况条件下工作的机械零件的耐磨性,采用等离子弧堆焊技术,制备硼化物强化铁基堆焊合金.借助OM,SEM和XRD等分析手段对合金组织和硼化物相形貌进行分析,并与未加入硼的Fe-Cr-C的堆焊合金进行对比.结果表明:堆焊合金中加入w(B)45%可改变基体的组织组成及硼化物的数量和分布形态,从而改善耐磨性.硼化物由大量菊花状M23(C,B)6和少量块状M7(C,B)3相组成,BC4与Cr2B的数量较少.耐磨粒磨损试验结果表明:堆焊合金的耐磨性随着硼含量的增加而先增大后下降,加入w(B)4.5%的堆焊层中形成的大量高硬度硼化物分布在具有较高强韧性的马氏体和奥氏体基体上,使其具有最佳的耐磨性,其磨损量仅为未加入硼时的1/6.%In order to improve the wear resistance of parts of machines in enviroments where they undergo severe conditions, Fe-based hardfacing alloy reinforced with borides were prepared under plasma transferred arc weld-surfacing process (PTA). The microstructure and borides morphology were investigated by means of OM, SEM and XRD, which was compared to the Fe-Cr-C hardfacing alloy. The results showed that the microstructure of the matrix and contents and distribution were changed as a result of the addition of 4.5% B in hardfacing alloys, which led to the improvement of wear resistance significantly. The borides consisted of high volume fraction of rosette M23(C,B)6 and little volume fraction of blocky M7(C B)3, the content of BC4 and Cr2B was very little. The abrasion experimental results showed that the wear resistance firstly increased and afterwards decreased as the B content increased, the microstructure characteristic with a high volume fraction of borides with high microhardness were distributed in the martensite and austenite matrix with high strength and toughness as the addition of 4.5%B in Fe-Cr-C hardfacing alloy, which suggested that the hardfacing layers had a

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

    CERN Document Server

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2015-04-01

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

  10. Atomic site preferences and its effect on magnetic structure in the intermetallic borides M{sub 2}Fe(Ru{sub 0.8}T{sub 0.2}){sub 5}B{sub 2} (M=Sc, Ti, Zr; T=Ru, Rh, Ir)

    Energy Technology Data Exchange (ETDEWEB)

    Brgoch, Jakoah, E-mail: jrbrgoc@gmail.com [Department of Chemistry, Iowa State University, Ames, IA 50011 (United States); Mahmoud, Yassir A. [Department of Chemistry, Iowa State University, Ames, IA 50011 (United States); Miller, Gordon J., E-mail: gmiller@iastate.edu [Department of Chemistry, Iowa State University, Ames, IA 50011 (United States)

    2012-12-15

    The site preference for a class of intermetallic borides following the general formula M{sub 2}Fe(Ru{sub 0.8}T{sub 0.2}){sub 5}B{sub 2} (M=Sc, Ti, Zr; T=Ru, Rh, Ir), has been explored using ab initio and semi-empirical electronic structure calculations. This intermetallic boride series contains two potential sites, the Wyckoff 2c and 8j sites, for Rh or Ir to replace Ru atoms. Since the 8j site is a nearest neighbor to the magnetically active Fe atom, whereas the 2c site is a next nearest neighbor, the substitution pattern should play an important role in the magnetic structure of these compounds. The substitution preference is analyzed based on the site energy and bond energy terms, both of which arise from a tight-binding evaluation of the electronic band energy, and are known to influence the locations of atoms in extended solids. According to these calculations, the valence electron-rich Rh and Ir atoms prefer to occupy the 8j site, a result also corroborated by experimental evidence. Additionally, substitution of Rh or Ir at the 8j site results in a modification of the magnetic structure that ultimately results in larger local magnetic moment on the Fe atoms. - Graphical abstract: The site preference for electron rich atoms to occupy the 8j (gray) site is identified in these intermetallic borides, while the magnetic structure is modified as a function of the substituted atoms band center. Highlights: Black-Right-Pointing-Pointer We identify the energetics dictating the site preference in a series of intermetallic borides. Black-Right-Pointing-Pointer Establish substitution rules for use in future directed synthetic preparations. Black-Right-Pointing-Pointer Identified changes in magnetic structure that accompany the site preference.

  11. Dysprosium selective potentiometric membrane sensor

    Energy Technology Data Exchange (ETDEWEB)

    Zamani, Hassan Ali, E-mail: haszamani@yahoo.com [Department of Applied Chemistry, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of); Faridbod, Farnoush; Ganjali, Mohammad Reza [Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of)

    2013-03-01

    A novel Dy(III) ion-selective PVC membrane sensor was made using a new synthesized organic compound, 3,4-diamino-N Prime -((pyridin-2-yl)methylene)benzohydrazide (L) as an excellent sensing element. The electrode showed a Nernstian slope of 19.8 {+-} 0.6 mV per decade in a wide concentration range of 1.0 Multiplication-Sign 10{sup -6}-1.0 Multiplication-Sign 10{sup -2} mol L{sup -1}, a detection limit of 5.5 Multiplication-Sign 10{sup -7} mol L{sup -1}, a short conditioning time, a fast response time (< 10 s), and high selectivity towards Dy(III) ion in contrast to other cations. The proposed sensor was successfully used as an indicator electrode in the potentiometric titration of Dy(III) ions with EDTA. The membrane sensor was also applied to the F{sup -} ion indirect determination of some mouth washing solutions and to the Dy{sup 3+} determination in binary mixtures. Highlights: Black-Right-Pointing-Pointer The novelty of this work is based on the high affinity of the ionophore toward the Dy{sup 3+} ions. Black-Right-Pointing-Pointer This technique is very simple, fast and inexpensive and it is not necessary to use sophisticated equipment. Black-Right-Pointing-Pointer The newly developed sensor is superior to the formerly reported Dy{sup 3+} sensors in terms of selectivity.

  12. The magnetocaloric effect in dysprosium

    Science.gov (United States)

    Benford, S. M.

    1979-01-01

    The magnetocaloric effect in polycrystalline Dy was measured in the 84-280-K range in measuring fields from 1 to 7 T. These adiabatic temperature changes reflect structural changes in Dy with applied field and temperature, and include the first magnetocaloric data for a helical antiferromagnet. Above the Neel point (179 K) a field increase always caused heating; below the Neel point fields less than about 2 T cause cooling for some values of initial temperature. The largest temperature increase with a 7 T field occurs at the Neel point and at fields below 2 T near the Curie point. For refrigeration purposes the optimal working region for a Dy cooling element is field dependent.

  13. Microstructure and dielectric properties of dysprosium-doped barium titanate ceramics Microestrutura e propriedades dielétricas de cerâmicas de titanato de bário dopado com disprósio

    Directory of Open Access Journals (Sweden)

    Y. Pu

    2005-09-01

    Full Text Available The substitution behavior and lattice parameter of barium titanate between solid_solubility with a dopant concentration in the range of 0.25 to 1.5 mol% are studied. The influences of dysprosium-doped fraction on the grain size and dielectric properties of barium titanate ceramic, including dielectric constant and breakdown electric field strength, are investigated via scanning electronic microscopy, X-ray diffraction and electric property tester. The results show that, at a dysprosium concentration of 0.75 mol%, the abnormal grain growth is inhibited and the lattice parameters of grain rise up to the maximum because of the lowest vacancy concentration. In addition, the finegrain and high density of barium titanate ceramic result in its excellent dielectric properties. The relative dielectric constant (25 °C reaches to 4100. The temperature coefficient of the capacitance varies from -10 to 10% within the temperature range of -15 °C -100 °C, and the breakdown electric field strength (alternating current achieves 3.2 kV/mm. These data suggest that our barium titanate could be used in the manufacture of high voltage ceramic capacitors.Foram estudados o comportamento da substituição e o parâmetro de rede de titanato de bário da solubilidade sólida com uma concentração de dopante na faixa 0,25-1,5 mol%. As influências da fração do dopante disprósio no tamanho de grão e nas propriedades dielétricas da cerâmica de titanato de bário, incluindo constante dielétrica e rigidez dielétrica foram investigadas por meio de microscopia eletrônica de varredura, difração de raios X e teste de propriedades elétricas. Os resultados mostram que a uma concentração de disprósio de 0,75 mol% o crescimento anormal de grão é inibido e os parâmetros de rede aumentam até um máximo devido a menor concentração de vacâncias. Além disso, as cerâmicas de grãos pequenos e alta densidade resultam em excelentes propriedades dielétricas. A

  14. Neodymium Dysprosium Modified Starch- coated Magnetic Fluid Preparation of Ferrite%淀粉包覆镝钕改性铁氧体磁性液体的制备

    Institute of Scientific and Technical Information of China (English)

    林穗云; 周育辉

    2011-01-01

    In this paper, in order to obtain the ferrite magnetic fluids of higher saturation magnetic intensity with simple technology, nanometer magnetite ( Fe3O4 ) particles ware prepared by chemical co - precipitation. And to a certain proportion of Dysprosium Neodymium ferrite magnetic fluids on the modification, we selected starch prepara- tion for the relief of water - based coating of rare earth iron oxide magnetic fluid composites. We also investigated the amount of Nd - Dy, the amount of coating agent, reaction temperature, coating temperature on the performance of the products and the effects of particle size, and its preliminary characterization was also performed . Through experiment,we summed up, under n (Fe) : [ n ( Nd3+ ) + n ( Dy3+ ) ] = 30:1 and n ( Fe3 + ) : n ( Fe2 + ) = 1.70 ~ 1. 75, the ratio for use of dysprosium and neodymium is n(Dy3+ ) : n(Nd3+ ) =4:1, 25%NH3 · H2O(A. R. ) as precipitating agent and pH value conditioner; the reacting system temperature was controlled in 35 ℃, and the pH value was adjusted to 9 ~ 11 ; the best dosage of starch as the relief is O. 0050g each 6OraL magnetic fluids, the temperature of surfactant was controlled in 50℃ and the pH value was adjusted to 2 ~ 3. In such system under the conditions of a water - based rare - earth compound Nd Dy Fe Magnetic, fluid magnetic oxygen was higher than or- dinary water- based ferrite.%为制备工艺简单且饱和磁化强度高的磁流体,本文采用化学共沉淀法制得了纳米磁性Fe304粒子.然后以一定比例的镝钕对铁氧体磁流体改性,选择淀粉为包覆剂制备水基稀土复合铁氧磁流体.考察了镝钕的用量、包覆剂的用量、反应温度、包覆温度等因素对产物粒径及性能的影响,并对其进行了初步的性能表征.实验总结出适宜的条件:在n(Fe):[n(Nd3+)+n(Dy3+)]=30:1,n(Fe3+):n(Fe2+)=1.70~1.75

  15. 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

    Energy Technology Data Exchange (ETDEWEB)

    Misse, Patrick R.N.; Mbarki, Mohammed [Institute of Inorganic Chemistry, RWTH Aachen University, 52066 Aachen (Germany); Fokwa, Boniface P.T., E-mail: boniface.fokwa@ac.rwth-aachen.de [Institute of Inorganic Chemistry, RWTH Aachen University, 52066 Aachen (Germany)

    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.

  16. 表面修饰对镝铁氧体纳米磁粒子的合成及其磁性能的影响%Effect of Surface Modification on Formation and Magnetic Property of Dysprosium Ferrite Nanomagnetic Particles

    Institute of Scientific and Technical Information of China (English)

    陈静; 张茂润; 邓真娟

    2011-01-01

    利用湿化学法制备镝铁氧体纳米磁粒子时,用适量的阴离子表面活性剂进行表面修饰,能够有效地控制磁粒子的粒径,同时避免干燥时产生硬团聚.文章介绍了用月桂酸、月桂酸钠、正十二烷基硫酸钠对磁粒子进行表面修饰的研究结果,探讨了三者及其用量对磁粒子的形成及磁性能的影响.借助X射线衍射仪(XRD)、透射电镜(TEM)、振动样品磁强计(VSM)、红外光谱仪(IR)对产物的性能进行了表征.结果表明,用月桂酸修饰后的产物具有Fe3O4磁粒子的晶型结构且结晶度高、磁性能优异、平均粒径约16nm;用月桂酸钠、正十二烷基硫酸钠修饰后的产物不具有Fe3O4磁粒子的晶型结构,结晶度低且磁性能差.%When wet chemical method are use to prepare dysprosium-doped ferrite magnetic nanoparticles, right a-mount of anionic surfactant were doped as surface modification, which can effectively control the size of magnetic particles, and avoid producing hard reunion when dry out. This paper introduces the research results of magnetic particle surface modification by using lauric acid, laurel acid sodium and lauryl sodium sulfate, discusses the effect of lauric acid, laurel acid sodium and lauryl sodium sulfate and their dosages on the formation of magnetic and its magnetic property. The properties of the product can be characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), infrared spectrometer (IR). The results showed that the product modified with lauric acid have a crystalline structure of Fe3O4 magnetic particles and high crystallin-ity, excellent magnetic properties. The average particle size is about 16 nm; the product modified with laurel acid sodium and lauryl sodium sulfate does not have the crystalline structure of Fe3O4 magnetic particles, with low crystal-linity and low magnetic property.

  17. Computer Modeling of Ceramic Boride Composites

    Science.gov (United States)

    2014-11-01

    the following summands: z VAB VV AB z BBB BB B z AAA AA A e dU Sde dU Sde dU Sd ∂ ∂ ⋅ = ∂ ∂ ⋅ = ∂ ∂ ⋅ = )(1 ; )(1 ; )(1 σσσ . (84) Here σA, σB...ABA z VAB VVz AAA AA A C C e dU SdC C e dU Sd σσσ −+=         ∂ ∂ ⋅ −+ ∂ ∂ ⋅ = 1 )(11)(1* , (85) Distribution A: Approved for public release

  18. Synthesis and crystal structures of α- and β-modifications of Cr 2IrB 2 containing 4-membered B 4 chain fragments, the τ-boride Cr 7.9Ir 14.1B 6 and orthorhombic Cr 2B

    Science.gov (United States)

    Kotzott, Dominik; Ade, Martin; Hillebrecht, Harald

    2008-03-01

    Single crystals of two forms of Cr 2IrB 2, the τ-boride Cr 7.9Ir 14.1B 6 and orthorhombic Cr 2B were synthesised from the elements at temperatures between 1450 and 1650 °C. α-Cr 2IrB 2 was obtained at 1650 °C and crystallizes in the Mo 2IrB 2 crystal structure type ( oP20, Pnnm, Z = 4, a = 9.210(1) Å, b = 7.112(1) Å, c = 2.9833(5) Å, 493 refl., 27 param. R1( F) = 0.0220, wR2( F2) = 0.0521) containing 4-membered B 4 chain fragments with the terminating B atoms in trans position. β-Cr 2IrB 2 (1450 °C) forms a low temperature form in a new crystal structure type ( oC40, Cmcm, Z = 8, a = 3.0024(7) Å, b = 9.945(2) Å, c = 13.236(2) Å, 424 refl., 28 param., R1( F) = 0.0279, wR2( I) = 0.0532) containing B 4 chain fragments of trigonal prisms BM 6 with the terminating B atoms in cis position. These B 4 units were observed for the first time. A structure refinement with single crystal data was done for the τ-boride Cr 7.9Ir 14.1B 6 ( Fm3¯m, a = 11.2024(19) Å, 151 refl., 17 param., R1( F) = 0.0275, wR2( F2) = 0.0297). Refinement of single crystal data shows that orthorhombic Cr 2B ( oF48, Fddd, Z = 16, a = 4.275(2) Å, b = 7.452(3) Å, c = 14.795(5) Å, 214 refl., 17 param., R1( F) = 0.0251, wR2( F2) = 0.0625) belongs to the CuMg 2 type and not to the Mn 4B type with partial boron occupation. The compositions were confirmed by EDX and WDX measurements.

  19. (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

    Energy Technology Data Exchange (ETDEWEB)

    Salamakha, Leonid P. [Institute of Solid State Physics, TU Wien, A-1040 Wien (Austria); Sologub, Oksana, E-mail: oksana.sologub@univie.ac.at [Institute of Solid State Physics, TU Wien, A-1040 Wien (Austria); Stöger, Berthold [Institute of Chemical Technologies and Analytics, TU Wien, A-1040 Wien (Austria); Michor, Herwig; Bauer, Ernst [Institute of Solid State Physics, TU Wien, A-1040 Wien (Austria); Rogl, Peter F. [Institute of Physical Chemistry, University of Vienna, A-1090 Wien (Austria)

    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

  20. Synthesis of niobium borides by powder metallurgy methods using Nb2O5, B2O3 and Mg blends%采用混合Nb2O5,B2O3和Mg粉末冶金法合成硼化铌

    Institute of Scientific and Technical Information of China (English)

    Özge Balcı; Duygu Ağaoğulları; M. Lütfi Öveçoğlu; İsmail Duman

    2016-01-01

    在强还原剂条件下,以相关的金属氧化物为原材料,采用粉末冶金法成功合成具有不同含量NbB、NbB2和Nb3B4相的硼化铌粉末和单相NbB粉末。在室温下使用高能球磨机球磨Nb2O5、B2O3和 Mg混合粉末。随后,利用HCl浸出除去球磨粉末中无用的MgO相,合成最终产物NbB−NbB2−Nb3B4,产物在1500°C下退火4 h,以便观察硼化物之间的转换。采用XRD、DSC、PSA、SEM/EDX、TEM和 VSM表征该产物。研究球磨时间(达9 h)对产物形成、显微组织和热行为的影响。化学计量混合粉末经2 h球磨后,发生了还原反应。在不存在任何二次相和杂质时,通过机械化学法,球磨5 h并采用4 mol/L HCl浸出,得到高纯纳米尺寸NbB−NbB2−Nb3B4粉末。经退火处理后,纯的纳米尺寸NbB−NbB2−Nb3B4粉末转变为单相NbB,不存在NbB2和Nb3B4相。%Niobium boride powders having NbB, NbB2 and Nb3B4 phases in various amounts and single phase NbB powders were successfully synthesized by using powder metallurgy methods from related metal oxide raw materials in the presence of a strong reducing agent. Nb2O5, B2O3 and Mg powder blends were milled at room temperature by a high-energy ball mill for different time. Subsequently, undesired MgO phase was removed from the milled powders by HCl leaching to constitute NbB−NbB2−Nb3B4 as final products and they were subjected to an annealing process at 1500 °C for 4 h to observe probable boride transformation. Characterization was carried out by XRD, DSC, PSA, SEM/EDX, TEM and VSM. The effects of milling time (up to 9 h) on the formation, microstructure and thermal behavior of the final products were investigated. Reduction reaction took place after milling stoichiometric powder blends for 2 h. Nano-sized NbB−NbB2−Nb3B4 powders in high purity were obtained in the absence of any secondary phase and any impurity via mechanochemistry by milling for 5 h and leaching with 4 mol/L HCl

  1. 纳米SiO2负载的过渡金属硼化物对AP热分解的催化作用%Catalytic Activity of Nano-silica Supported Transition-metal Borides on the Thermal Decomposition of Ammonium Perchlorate

    Institute of Scientific and Technical Information of China (English)

    李茸; 刘祥萱; 王煊军

    2012-01-01

    采用化学还原法制备纳米NiB/SiO2、CoB/SiO2、MoB/SiO2催化剂,通过热重-差热分析(TG-DTA)研究了其对AP热分解过程的催化作用.结果表明,负载过渡金属硼化物催化剂对AP分解的催化活性顺序为:CoB/SiO2>NiB/SiO2> MoB/SiO2;加入质量分数5%的CoB/SiO2使AP高温热分解峰温度降低166.2℃;SiO2载体将CoB晶型转化推迟了 110℃左右,改善了催化剂的热稳定性.%The nano-silica supported transition metal catalysts NiB/SiO2 , CoB/SiO2 , MoB/SiO2 were prepared by chemical reduction method. Their catalytic activity on the thermal decomposition of ammonium perchlorate (AP) was studied by TG-DTA. Results show that catalytic activity of nano-silica supported transition metal borides for the thermal decomposition of AP decreases in the order: CoB/SiO2 > NiB/SiO2 >MoB/SiO2. The CoB/SiO2 (mass ration of 5%) catalyst makes the high-temperature thermal decomposition temperature of AP decrease by 166. 2℃. The SiO2 carrier makes the crystal transformation temperature delay about 110℃, revealling the improvement of thermal stability of the catalyst.

  2. NICKEL ALUMINIDE SYNTHESIS REINFORCED WITH MOLYBDENUM BORIDE COMPOSITE

    Directory of Open Access Journals (Sweden)

    Mr. Khosen ф Ri

    2016-06-01

    Full Text Available The authors study obtaining a composite material NiAl - Mo2B5 while carrying out thermally coupled reactions of self-propagating high-temperature synthesis with a deoxidizing aluminothermal stage. The authors established ultimate and phase composition of the obtained composite. The microstructure is studied. It is shown that the composite consists of the intermetallic phase NiAl with Mo2B5 inclusions.

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

    Science.gov (United States)

    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%.

  4. Rare earth boride electron emitter materials fabrication and evaluation

    Science.gov (United States)

    Swanson, L. W.; Davis, P. R.; Gesley, M. A.

    1982-03-01

    Techniques were developed for routine preparation of single crystal rods of LaB6, CeB6 and PrB6 by arc float zone refining. Single crystal, oriented samples were prepared from these rods and mounted as cathodes for testing. Several mounting systems were used, and flat, pointed cone and truncated cone thermionic cathodes were studied. Pointed field emitters of LaB6(100) were also investigated. Variation of thermionic emitted current density and thermal stability of materials were studied as functions of rare earth element, bulk stoichiometry and crystal orientation. Life tests were performed on several different LaB6(100) cathodes. One such cathode operated for over 3000 hours at approximately 10 A/sq cm emitted current density with no serious physical degradation. Surface properties of the materials were investigated by various surface analysis techniques.

  5. Nanomechanical and nanotribological behaviors of hafnium boride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chowdhury, Shahla, E-mail: chowdhury.shahla@gmail.com [Department of Mechanical Science and Engineering, University of Illinois at Urbana Champaign, 1206 W Green Street, Urbana, IL 61801 (United States); Department of Mechanical Engineering, Texas A& M University, 3123 TAMU, College Station, TX (United States); Polychronopoulou, Kyriaki, E-mail: kpolychronopoulou@gmail.com [Department of Mechanical Science and Engineering, University of Illinois at Urbana Champaign, 1206 W Green Street, Urbana, IL 61801 (United States); Mechanical Engineering Department, Khalifa University of Science Technology & Research, P.O Box 127788, Abu Dhabi (United Arab Emirates); Cloud, Andrew, E-mail: andrewncloud@gmail.com [Department of Materials Science and Engineering, University of Illinois at Urbana Champaign, 1304 W Green Street, Urbana, IL 61801 (United States); Abelson, John R., E-mail: abelson@illinois.edu [Department of Materials Science and Engineering, University of Illinois at Urbana Champaign, 1304 W Green Street, Urbana, IL 61801 (United States); Polycarpou, Andreas A., E-mail: apolycarpou@tamu.edu [Department of Mechanical Science and Engineering, University of Illinois at Urbana Champaign, 1206 W Green Street, Urbana, IL 61801 (United States); Department of Mechanical Engineering, Texas A& M University, 3123 TAMU, College Station, TX (United States)

    2015-11-30

    Nanocrystalline HfB{sub 2}, HfBN and multilayer HfB{sub 2}/HfBN films were deposited using chemical vapor deposition. Half of the amorphous as-deposited films were subjected to annealing at 700 °C to obtain their annealed equivalent samples. Nanoindentation and nanoscratch experiments were performed to measure their mechanical properties, friction and scratch/wear behavior. The annealed films showed higher hardness values compared to the as-deposited films, with the HfB{sub 2} film exhibiting the highest hardness. All three films exhibited similar shear strength around 3 GPa for as-deposited and 5.5 GPa for annealed films, implying reduced delamination propensity for the annealed samples. The annealed HfBN and multilayer HfB{sub 2}/HfBN films exhibited lower friction and wear, compared to the rest of the films. Specifically, the annealed multilayer HfB{sub 2}/HfBN films, exhibited an order of magnitude lower wear, compared to the HfB{sub 2} films, making them excellent candidates for low friction and low wear hard coating applications. - Highlights: • Hard, dense thin films of HfB2/HfBN were deposited using chemical vapor deposition. • Annealed films exhibited high shear strength, and thus reduced propensity to delamination. • Hardness values alone do not correlate with friction and wear performance. • Annealed multi-layered HfB2/HfBN films exhibited outstanding friction and wear resistance.

  6. Fundamental Thermal and Mechanical Properties of Boride Ceramics

    Science.gov (United States)

    2014-02-28

    fixture based on Grathwohl’s design were used. Specimens were loaded onto the fixture and secured using a cyanoacrylate adhesive . The environmental...became larger and the glassy phase transitioned from a smooth to a reticulated coating. The average thickness of the outer glassy scale was ~5.6 µm

  7. Dysprosium-free melt-spun permanent magnets.

    Science.gov (United States)

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

    2014-02-12

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

  8. Structural and magnetic study of dysprosium substituted cobalt ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Hemaunt, E-mail: hvatsal@gmail.com [Department of Physics, Govind Ballabh Pant University of Agr. & Technology, Pantnagar, Uttarakhand 263145 (India); Srivastava, R.C. [Department of Physics, Govind Ballabh Pant University of Agr. & Technology, Pantnagar, Uttarakhand 263145 (India); Pal Singh, Jitendra [Advanced Analysis Centre, Korea Institute of Science and Technology, Seoul 02792 (Korea, Republic of); Negi, P. [Department of Physics, Govind Ballabh Pant University of Agr. & Technology, Pantnagar, Uttarakhand 263145 (India); Agrawal, H.M. [Advanced Analysis Centre, Korea Institute of Science and Technology, Seoul 02792 (Korea, Republic of); Das, D. [UGC-DAE CSR Kolkata Centre, Kolkata 700098 (India); Hwa Chae, Keun [Advanced Analysis Centre, Korea Institute of Science and Technology, Seoul 02792 (Korea, Republic of)

    2016-03-01

    The present work investigates the magnetic behavior of Dy{sup 3+} substituted cobalt ferrite nanoparticles. X-ray diffraction studies reveal presence of cubic spinel phases in these nanoparticles. Raman spectra of these nanoparticles show change in intensity of Raman bands, which reflects cation redistribution in cubic spinel lattice. Saturation magnetization and coercivity decrease with increase of Dy{sup 3+}concentration in these nanoparticles. Room temperature Mössbauer measurements show the cation redistribution in these nanoparticles and corroborates the results obtained from Raman Spectroscopic measurements. Decrease in magnetization of Dy{sup 3+} substituted cobalt ferrite is attributed to the reduction in the magnetic interaction and cation redistribution. - Highlights: • Slight decrease in crystallite size after Dy{sup 3+} doping. • Saturation magnetization and coercivity decrease after Dy{sup 3+} doping. • Mössbauer measurements show the cation redistribution in the samples.

  9. Dysprosium Acetylacetonato Single-Molecule Magnet Encapsulated in Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Ryo Nakanishi

    2016-12-01

    Full Text Available Dy single-molecule magnets (SMMs, which have several potential uses in a variety of applications, such as quantum computing, were encapsulated in multi-walled carbon nanotubes (MWCNTs by using a capillary method. Encapsulation was confirmed by using transmission electron microscopy (TEM. In alternating current magnetic measurements, the magnetic susceptibilities of the Dy acetylacetonato complexes showed clear frequency dependence even inside the MWCNTs, meaning that this hybrid can be used as magnetic materials in devices.

  10. Microscopic study of neutron-rich dysprosium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, Carlos E. [Universidad Veracruzana, Facultad de Fisica e Inteligencia Artificial, Xalapa (Mexico); Universidad Nacional Autonoma de Mexico, Facultad de Ciencias, Apartado Postal 70-542, Mexico D.F. (Mexico); Velazquez, Victor [Universidad Nacional Autonoma de Mexico, Facultad de Ciencias, Apartado Postal 70-542, Mexico D.F. (Mexico); Lerma, Sergio [Universidad Veracruzana, Facultad de Fisica e Inteligencia Artificial, Xalapa (Mexico)

    2013-01-15

    Microscopic studies in heavy nuclei are very scarce due to large valence spaces involved. This computational problem can be avoided by means of the use of symmetry-based models. Ground-state, {gamma} and {beta} bands, and their B(E2) transition strengths in {sup 160-168}Dy isotopes, are studied in the framework of the pseudo-SU(3) model which includes the preserving symmetry Q . Q term and the symmetry-breaking Nilsson and pairing terms, systematically parametrized. Additionally, three rotor-like terms are considered, whose free parameters, fixed for all members of the chain, are used to fine tune the moment of inertia of rotational bands and the band head of {gamma} and {beta} bands. The model succesfully describes in a systematic way rotational features in these nuclei and allows to extrapolate toward the midshell nucleus {sup 170}Dy. The results presented show that it is possible to study a full chain of isotopes or isotones in the region with the present model. (orig.)

  11. Photodissociation spectroscopy of the dysprosium monochloride molecular ion

    CERN Document Server

    Dunning, Alexander; Showalter, Steven J; Puri, Prateek; Kotochigova, Svetlana; Hudson, Eric R

    2015-01-01

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

  12. FTIR and Electrical Study of Dysprosium Doped Cobalt Ferrite Nanoparticles

    Directory of Open Access Journals (Sweden)

    Hemaunt Kumar

    2014-01-01

    Full Text Available We have studied the role of Dy3+ doping on the XRD, TEM, FTIR, and dielectric and electrical properties of CoFe2O4 at room temperature. Cubic spinel phase of CoFe2−xDyxO4 (x = 0.00, 0.05, 0.10, and 0.15 was synthesized by using different sintering temperatures (300, 500, 700, and 900°C. The two absorption bands ν1 and ν2 are observed in Fourier transform infrared spectroscopy (FTIR spectra corresponding to the tetrahedral and octahedral sites, which show signature of spinel structure of the sample. For the sample sintered at 300°C, the dielectric constant is almost unchanged with the frequency at the particular concentrations of x = 0.00 and 0.05. Similar result is obtained for the sample sintered at 500°C (x = 0.10, 0.15, 700°C (x = 0.05, 0.10, and 0.15, and 900°C (x = 0.05, 0.10. An increase in the dielectric constant was observed for the undoped cobalt ferrite sintered at 500, 700, and 900°C. The values of electrical resistivity of the materials vary from ~105 to 109 Ω-cm.

  13. Adsorption of D113 Resin for Dysprosium(Ⅲ)

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The adsorption behavior and mechanism of D113 resin for Dy(Ⅲ) was investigated by using the method of resin adsorption. Experimental results show that the optimum medium pH of adsorption of D113 resin for Dy3+ is pH=6.00 in the HAc-NaAc medium. The static adsorption capacity of D113 resin for Dy3+chemical analysis and IR spectra.

  14. 1300-nm gain obtained with dysprosium-doped chloride crystals

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-03-01

    Dy{sup 3+} - doped chloride crystals have high 1300-nm emission quantum yields. Pump - probe experiments on La Cl{sub 3}:Dy{sup 3+} demonstrate optical gain consistent with predictions based on spectroscopic cross sections and lifetimes.

  15. Microscopic study of neutron-rich Dysprosium isotopes

    CERN Document Server

    Vargas, Carlos E; Lerma, Sergio; 10.1140/epja/i2013-13004-1

    2013-01-01

    Microscopic studies in heavy nuclei are very scarce due to large valence spaces involved. This computational problem can be avoided by means of the use of symmetry based models. Ground-state, gamma and beta-bands, and their B(E2) transition strengths in 160-168Dy isotopes, are studied in the framework of the pseudo-SU(3) model which includes the preserving symmetry Q.Q term and the symmetry-breaking Nilsson and pairing terms, systematically parametrized. Additionally, three rotor-like terms are considered whose free parameters, fixed for all members of the chain are used to fine tune the moment of inertia of rotational bands and the band-head of gamma and beta-bands. The model succesfully describes in a systematic way rotational features in these nuclei and allows to extrapolate toward the midshell nucleus 170Dy. The results presented show that it is possible to study full chain of isotopes or isotones in the region with the present model.

  16. Visible luminescence of dysprosium ions in oxyhalide lead borate glasses

    Science.gov (United States)

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

    2011-08-01

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

  17. MAGNETIC FIELD INDUCED FIRST-ORDER TRANSITIONS IN DYSPROSIUM ORTHOFERRITE

    OpenAIRE

    Eremenko, V.; Gnatchenko, S.; Kharchenko, N.; Lebedev, P.; Piotrowski, K; Szymczak, H.; Szymczak, R.

    1988-01-01

    New type of magnetic first-order phase transition induced by external magnetic field applied in the ab-plane in DyFeO3 is investigated using different magnetooptic techniques. The phenomenological model of this transition is proposed. The phase diagram in H-T plane has been obtained for various H orientation in the ab-plane.

  18. Boride ceramics covalent functionalization and its effect on the thermal conductivity of epoxy composites

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Zhi-Qiang, E-mail: yuzhiqiang@fudan.edu.cn [Department of Materials Science, Fudan University, 200433 Shanghai (China); Wu, Yicheng [Department of Materials Science, Fudan University, 200433 Shanghai (China); Wei, Bin; Baier, Horst [Institute of Lightweight Structures, Technical University Munich (TUM), Boltzmannstr. 15, D-85747 Garching (Germany)

    2015-08-15

    Zirconium diboride/aluminium oxide (ZrB{sub 2}/Al{sub 2}O{sub 3}) composite particles were functionalized with epoxide functionalized γ-glycidoxypropyltrimethoxysilane by the covalent bonding approach to improve the interfacial compatibility of composite particles in epoxy matrix. The composites of epoxy resin filled with functionalized ZrB{sub 2}/Al{sub 2}O{sub 3} were prepared by in situ bulk condensation polymerization of bisphenol A and epichlorohydrin in the presence of ZrB{sub 2}/Al{sub 2}O{sub 3}. The heat-conducting properties of composites were investigated by the finite element method (FEM) and the thermal conductivity test. The finite-element program ANSYS was used for this numerical analysis, and three-dimensional spheres-in-cube lattice array models were built to simulate the microstructure of composite materials for different filler contents. The thermal conductivity of composites was determined by laser flash method (LFA447 Nanoflash), using the measured heat capacity and thermal diffusivity, with separately entered density data. The results show that the effective chemical bonds are formed between ZrB{sub 2}/Al{sub 2}O{sub 3} and γ-glycidoxypropyltrimethoxysilane after the surface functionalization. The interfacial compatibility and bonding of modified particles with the epoxy matrix are improved. The thermal conductivities of functionalized composites with 3 vol% and 5 vol% loading are increased by 8.3% and 12.5% relative to the unmodified composites, respectively. Comparison of experimental values and calculated values of the thermal conductivity, the average relative differences are under 5%. The predictive values of thermal conductivity of epoxy composites are in reasonable agreement with the experimental values. - Highlights: • The surfaces of ZrB{sub 2}/Al{sub 2}O{sub 3} were functionalized by silane coupling agents. • The thermal conductivity (TC) of modified epoxy composites is improved significantly. • The FEM values of TC are in reasonable agreement with the experimental values.

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

    Science.gov (United States)

    2011-05-01

    the presence of small amounts of excess phases have no pronounced impact on the Young’s modulus values. The use of Ti-Zr solid solutions diborides as...has been predicted on the early stages of the present work, the semi-coherence of lattices on the phase interface has the crucial impact on structure...failure resistance, which results from their different microplasticity (microbrittleness) and relaxation ability. In order to evaluate the

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

    Energy Technology Data Exchange (ETDEWEB)

    Peters, Justin Steven [Iowa State Univ., Ames, IA (United States)

    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.

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

    Science.gov (United States)

    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

  2. Magnetic properties of Sm5Fe17 melt-spun ribbons and their borides

    Directory of Open Access Journals (Sweden)

    Tetsuji Saito

    2015-10-01

    Full Text Available Sm5Fe17 melt-spun ribbons exhibited low coercivity and partly or mostly consisted of the amorphous phase. Annealing of Sm5Fe17 melt-spun ribbon resulted in the formation of the Sm5Fe17 phase. The annealed Sm5Fe17 melt-spun ribbon exhibited a high coercivity. It was found that the addition of B to the Sm5Fe17 alloy resulted in the promotion of the Sm2Fe14B phase. Annealed Sm5Fe17Bx (x = 0.5 melt-spun ribbons consisted of the Sm5Fe17 phase together with the Sm2Fe14B and SmFe2 phases. On the other hand, annealed Sm5Fe17Bx (x = 1.0-1.5 melt-spun ribbons consisted of the Sm2Fe14B and SmFe2 phases without the Sm5Fe17 phase. The resultant Sm5Fe17Bx (x = 1.0-1.5 melt-spun ribbons still showed a coercivity of around 2 kOe. The annealed Sm5Fe17 melt-spun ribbon exhibited a high coercivity over 25 kOe and a remanence of 40 emu/g, whereas the annealed Sm5Fe17B1.0 melt-spun ribbon exhibited a high remanence of 65 emu/g and a coercivity of 2.0 kOe.

  3. Epitaxial Growth of Icosahedral Boride Semiconductors for Novel Energy Conversion Devices

    Energy Technology Data Exchange (ETDEWEB)

    Edgar, J.H.

    2006-01-03

    The chemical vapor deposition and properties of the boron-rich semiconductors B12As2 and B12P2 on 6H-SiC(0001) and silicon substrates were investigated. Crystalline, stoichiometric films were deposited between 1200 C and 1500 C using two types of reactants, hydrides (B2H6 and AsH3) for B12As2 and halides (BBr3 and PBr3) for B12P2. 6H-SiC proved to be the better substrate for B12As2 heteroepitaxy, in terms of the residual impurity concentrations. Films on Si substrates suffered from high concentrations of Si (up to 4at.%); in contrast, the Si and C concentrations in the B12As2 films deposited on 6H-SiC at 1300 C were at or below the detection limits of secondary ion mass spectrometry (SIMS). The deposition temperature was significant as films deposited at 1450 C contained high residual C and Si concentrations (>1020 cm-3), probably due to the decomposition of the substrate. The hydrogen concentration in all B12As2 films was relatively high, with a minimum concentration of 3x1019 cm-3 in undoped B12As2. SIMS measurements showed that the hydrogen concentration was directly proportional to and tracked the Si concentration, reaching values as high as 3 x 1020 cm-3. The structural properties of the B12As2 films were characterized by x-ray diffraction and transmission electron microscopy. The FWHM of typical high resolution x-ray rocking curves for the (333) peaks of the B12As2 films were 800 arcsec. The films are under tensile strain due the higher coefficient of thermal expansion for B12As2 than SiC. Rotational twins were present in B12As2 films deposited on (0001) oriented 6H-SiC substrates, as revealed by cross-sectional TEM and x-ray diffraction pole figures. While the c-plane 6H-SiC has six-fold rotational symmetry, rhombohedral B12As2 has only 3-fold symmetry (along its (111) axis), thus it randomly nucleates with two different in-plane orientations. The electrical properties of undoped and silicon-doped B12As2 deposited on semi-insulating 6H-SiC substrates were characterized by Hall effect measurements. The resistivity of p-type B12As2 films on semi-insulating 6H-SiC(0001) substrates was controllably varied over nearly four orders of magnitude by changing the concentrations of silicon into the films, incorporated by adding silane during deposition. The electrical properties of the B12As2 suffered from low hole mobilities, typically less than 3 cm2/V's. This was possibly a consequence of structural defects in the films. The resistivity of as-deposited undoped and silicon-doped B12As2 films decreased by two or more orders of magnitude after annealing at temperatures above 600 C in argon. This unexpected but reproducible effect of annealing on the resistivity of the semiconductor warrants further investigation. The properties of palladium, platinum, and chromium/platinum electrical contacts to B12As2 were tested at Pennsylvania State University. The Pd and Pt contacts exhibited nonlinear I-V characteristics and severe agglomeration upon annealing, but the Cr/Pt contacts were ohmic and remained smooth even after they were annealed at 750 C. The specific contact resistance of the Cr/Pt contacts dropped four orders of magnitude after samples were annealed in Ar for 30 s at 750 C. This reduction in specific contact resistance was linked to a simultaneous drop in the resistivity of B12As2 upon annealing. In subsequent experiments, a low specific contact resistance was also achieved when Cr/Pt was deposited on B12As2 films that were annealed prior to metallization instead of afterwards.

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

    Science.gov (United States)

    1990-01-01

    well known. 5.2.3. - Pyrolysis of boron-containing organic precursors. The pyrolysis is generally caried out at high temperature (> 13000C) under Ar...electrical measurements [701 would be largely due to the N site with the small ionization energy. Although v simple clasification of the three sites

  5. Luminescence of divalent europium activated spinels synthesized by combustion and the enhanced afterglow by dysprosium incorporation

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Haoyi, E-mail: manofchina@gmail.com; Jin, Yahong

    2016-05-01

    Herein we report a luminescent phenomenon of Eu{sup 2+} in the spinel MgAl{sub 2}O{sub 4} and ZnAl{sub 2}O{sub 4} samples which are successfully synthesized via a combustion method. The XRD shows cubic spinel structure is obtained from the prepared samples. The mean crystal sizes estimated from XRD data are 30 and 10 nm for MgAl{sub 2}O{sub 4} and ZnAl{sub 2}O{sub 4} respectively, and the large grain particles are the agglomeration of crystallites. The Eu{sup 2+} ions show a blue emission at around 480 nm and an afterglow phenomenon is observed after the removal of excitation. The afterglow spectrum of MgAl{sub 2}O{sub 4}: Eu{sup 2+}, Dy{sup 3+} shows two emissions at 480 and 520 nm while only one at 480 nm is observed in ZnAl{sub 2}O{sub 4}: Eu{sup 2+}, Dy{sup 3+}. The afterglow intensity and the persisting duration can be substantially enhanced by the Dy{sup 3+} incorporation because the trapping ability of the electron traps is reinforced. This is confirmed by the TL curves of the samples.

  6. Energy level decay and excited state absorption processes in dysprosium-doped fluoride glass

    Science.gov (United States)

    Gomes, Laércio; Librantz, André Felipe Henriques; Jackson, Stuart D.

    2010-03-01

    The primary excited state decay processes relating to the H613/2→H615/2˜3 μm laser transition in singly Dy3+-doped fluoride (ZBLAN) glass have been investigated in detail using time-resolved fluorescence spectroscopy. Selective laser excitation of the F69/2, H67/2 energy levels at 1125 nm and F611/2, H69/2 energy levels at 1358 nm established that the energy levels above the H611/2 level, excluding the F49/2 level, are entirely quenched by multiphonon emission in ZBLAN glass. The H611/2 and H613/2 energy levels emit luminescence with peaks at ˜1700 and ˜2880 nm, respectively, but at low quantum (luminescence) efficiencies. The quantum efficiency of the H611/2 level and H613/2 level is ˜9×10-5 and ˜1.3×10-2, respectively, for [Dy3+]=0.5 mol % based on calculations of the radiative lifetimes using the Judd-Ofelt theory. Excited state absorption (ESA) was detected by monitoring the rise time of the 1700 nm luminescence after tuning the probe wavelength across the spectral range from 1100 to 1400 nm. As a result of nonradiative decay of the higher excited states, ESA contributes to the heating of ˜3 μm fiber lasers based on Dy3+-doped fluoride glass. For [Dy3+] up to 4 mol %, we found no evidence of energy transfer processes between Dy3+ ions that influence the decay characteristics of the H611/2 and H613/2 energy levels.

  7. A naproxen complex of dysprosium intercalates into calf thymus DNA base pairs

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Mengsi; Jin, Jianhua; Xu, Guiqing [School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University, Xinxiang 453007 (China); Cui, Fengling, E-mail: fenglingcui@hotmail.com [School of Chemistry and Chemical Engineering, Key Laboratory of Green Chemical Media and Reactions, Ministry of Education, Henan Normal University, Xinxiang 453007 (China); Luo, Hongxia [Department of Chemistry, Renmin University of China, Beijing 100872 (China)

    2014-01-15

    Highlights: • Binding mode to ctDNA was studied by various methods. • Intercalation is the most possible binding mode. • Dynamic and static quenching occurred simultaneously. • Hydrophobic force played a major role. • Binding characteristic of rare earth complexes to DNA are dependent on the element. - Abstract: The binding mode and mechanism of dysprosium–naproxen complex (Dy–NAP) with calf thymus deoxyribonucleic acid (ctDNA) were studied using UV–vis and fluorescence spectra in physiological buffer (pH 7.4). The results showed that more than one type of quenching process occurred and the binding mode between Dy–NAP with ctDNA might be intercalation. In addition, ionic strength, iodide quenching and fluorescence polarization experiments corroborated the intercalation binding mode between Dy–NAP and ctDNA. The calculated thermodynamic parameters ΔG, ΔH and ΔS at different temperature demonstrated that hydrophobic interaction force played a major role in the binding process.

  8. Connecting mononuclear dysprosium single-molecule magnets to form dinuclear complexes via in situ ligand oxidation.

    Science.gov (United States)

    Yutronkie, Nathan J; Kühne, Irina A; Korobkov, Ilia; Brusso, Jaclyn L; Murugesu, Muralee

    2016-01-14

    A Dy2 complex, exhibiting SMM behaviour, and its Y analogue were prepared via in situ oxidation of Py2TTA, a pincer type ligand, followed by dimerisation. This unique metal complexation and subsequent dimerization were followed by solution NMR studies.

  9. A Linear Tetranuclear Dysprosium(III) Compound Showing Single-Molecule Magnet Behavior

    Energy Technology Data Exchange (ETDEWEB)

    Ke, Hongshan; Xu, Gong Feng; Guo, Yun-Nan; Gamez, Patrick; Beavers, Christine M; Teat, Simon J; Tang, Jinkui

    2010-04-20

    Although magnetic measurements reveal a single-relaxation time for a linear tetranuclear Dy(III) compound, the wide distribution of the relaxation time observed clearly suggests the presence of two slightly different anisotropic centres, therefore opening new avenues for investigating the relaxation dynamics of lanthanide aggregates.

  10. A Novel (4,6)-Connected Net Based on Dysprosium Benzenedicarboxylate, [Dy(OAc)(BDC)]n

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lei; LI Zhao-Ji; QIN Ye-Yan; CHENG Jian-Kai; YAO Yuan-Gen

    2008-01-01

    A new lanthanide coordination polymer, [Dy(OAc)(BDC)]n 1 (OAc= acetate, BDC = 1,4-benzenediacarboxylate), has been synthesized under hydrothermal conditions. Single-crystal X-ray diffraction analysis reveals that complex 1 has infinite zigzag Dy-OAc chains, which are further connected by BDC to form a 3D metal-organic framework. According to topology analysis, this framework can be characterized as (4,6)-connected (3.4.54)(32.4.56.66) net that has never been reported before. Crystal structure for 1: space group Pbca, a = 13.314(3), b = 8.0269(18), c = 20.275(5) A, V = 2166.8(9) A3, C10H7O6Dy, Mr= 385.66, Z = 8, Dc = 2.364 g/cm3, μ = 6.910 mm-1, F(000) = 1448, the final R = 0.0181 and wR = 0.0520.

  11. Photoluminescence and thermoluminescence properties of tricalcium phosphate phosphors doped with dysprosium and europium

    Indian Academy of Sciences (India)

    K Madhukumar; H K Varma; Manoj Komath; T S Elias; V Padmanabhan; C M K Nair

    2007-10-01

    The suitability of calcium phosphate crystals for thermoluminescence dosimetry (TLD) applications is investigated, owing to their equivalence to bone mineral. The and phases of tricalcium phosphate (TCP) were synthesized through wet precipitation and high temperature solid state routes and doped with Dy and Eu. The photoluminescence and thermoluminescence studies of the phosphors have been carried out. The TL properties were found to be highly dependent on the method of preparation of the material. Eu doping gave good PL emission, whereas Dy doping was more efficient in TL emission. -TCP was found to be less TL sensitive than -TCP, yet it was identified as a better phosphor material owing to its better fading characteristics. The dependence of TL of -TCP : Dy on the energy and dose of radiation, and on the doping concentration were studied. The TL intensity was observed to fade exponentially during a storage period of 20 days, but it stabilized at 70% of the initial value after 30 days. The optimum doping concentration was found to be 0.5 mol%.

  12. Extraction liquide-solide de Dysprosium(III) par le charbon actif ferromagnétique

    OpenAIRE

    khiri, khaira

    2014-01-01

    L’extraction liquide-solide de Dy(III) a été faite par le charbon actif ferromagnétique, dans un milieu nitré. L’effet de pH initial, concentration initial en ion Dy(III), le temps de contact, la force ionique, la température, la masse et l’élution ont été étudiés. La capacité de sorption augmente avec l’augmentation de la concentration initiale en Dy(III), le pH et la température. L’isotherme de Freundlich décrit mieux le processus d’extraction, ainsi que le modèle cinétique de p...

  13. Geometric and electronic structure of dysprosium thin films on tungsten surfaces Structural and magnetic properties

    CERN Document Server

    Moslemzadeh, N

    2001-01-01

    The rare earth thin films are frequently the focus of investigators due to their unusual structural and magnetic properties. Despite the potential interest of Dy/W systems to the surface/rare earth community, they have been little studied. This study is the first try of growing Dy on W(100) and W(112) and W(110) in which almost a complete set of information about film morphology and electronic structure of the surface and interface have been achieved. A set of different experiments have been done for this purpose including LEED, XPS, UPS (with synchrotron radiation) and STM. The growth modes of Dy on different W substrates (W(100), W(112) and W(110)) at RT and at elevated temperatures have been determined by XPS of Dy 3d sub 3 sub / sub 2 and W 4f intensities. Crystallographic ordering and the epitaxial relationship between adsorbate Dy and different W substrates have been studied with LEED and the effect of annealing temperature on the resultant superstructures was investigated. As a complementary study to t...

  14. Cerium: an unlikely replacement of dysprosium in high performance Nd-Fe-B permanent magnets.

    Science.gov (United States)

    Pathak, Arjun K; Khan, Mahmud; Gschneidner, Karl A; McCallum, Ralph W; Zhou, Lin; Sun, Kewei; Dennis, Kevin W; Zhou, Chen; Pinkerton, Frederick E; Kramer, Matthew J; Pecharsky, Vitalij K

    2015-04-24

    Replacement of Dy and substitution of Nd in NdFeB-based permanent magnets by Ce, the most abundant and lowest cost rare earth element, is important because Dy and Nd are costly and critical rare earth elements. The Ce, Co co-doped alloys have excellent high-temperature magnetic properties with an intrinsic coercivity being the highest known for T ≥ 453 K.

  15. Studies on Preparation of Dysprosium - 165 Metallic Macroaggregates for the Treatment of Rheumatoid Arthritis

    Energy Technology Data Exchange (ETDEWEB)

    Park, Kyung Bae; Kim, Jae Rok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    1994-07-15

    Irradiation of 20 mg of natural Dy(NO{sub 3})3 in a neutron flux of 2 X10{sup 13} n/cm{sup 2} sec for 4 hours gave 5.76 Ci of {sup 165}Dy (specific activity, 610 mCi/mg Dy) with high radionuclidic purity (>99.9%). {sup 165}Dy-MA was prepared in a quantitative yield by reacting the aqueous solution of {sup 165}Dy(NO{sub 3})3 with sodium borohydride solution in 0.2N NaOH. Coulter particle analyzer exhibited mean particle size of 2.6 mum (range 1 approx 6 mum). Even though the {sup 165}Dy-MA suspension in saline was stored at 37 .deg. C for 24 hours of autoclaved at 121 .deg. C for 30 minutes, there was no significant change in particle size and leakage problem indicating the prepared {sup 165}Dy-MA is sufficiently stable. In-vivo retention studies were carried out by administering {sup 165}Dy-MA into the knee joint space of normal rabbits. Gamma camera analysis showed high retention in joint space of normal rabbits. Gamma camera analysis showed high retention in joining space even at 24 hours after administration (>99.9%) The ease with which the{sup 165}Dy-MA can be made in the narrow size range and their high in vitro and vivo stability make them attractive agents for radiation synovectomy.

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

    Science.gov (United States)

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

    2015-03-06

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

  17. Dysprosium(III)-diethylenetriaminepentaacetate complexes of aminocyclodextrins as chiral NMR shift reagents.

    Science.gov (United States)

    Wenzel, T J; Miles, R D; Zomlefer, K; Frederique, D E; Roan, M A; Troughton, J S; Pond, B V; Colby, A L

    2000-01-01

    A metal chelating ligand is bonded to alpha-, beta-, and gamma-cyclodextrin by the reaction of diethylenetraminepentaacetic dianhydride with the corresponding 6-mono- and 2-mono(amine)cyclodextrin. Adding Dy(III) to the cyclodextrin derivatives causes shifts in the (1)H-NMR spectra of substrates such as propranolol, tryptophan, aspartame, carbinoxamine, pheniramine, doxylamine, and 1-anilino-8-naphthalenesulfonate. The Dy(III)-induced shifts enhance the enantiomeric resolution in the NMR spectra of several substrates. Enhancements in enantiomeric resolution using cyclodextrin derivatives with the amine tether are compared to previously described compounds in which the chelating ligand is attached through an ethylenediamine tether. In general, the Dy(III) complex of the 6-beta-derivative with the amine tether is a more effective chiral resolving agent than the complex with the ethylenediamine tether. The opposite trend is observed with the 2-beta-derivatives. The presence of the chelating ligand in the 2-beta-derivative hinders certain substrates from entering the cavity. For cationic substrates, evidence suggests that a cooperative association involving inclusion in the cavity and association with the Dy(III) unit occurs. Enhancements in enantiomeric resolution in the spectrum of tryptophan are greater for the secondary alpha- and gamma-derivatives than the beta-derivative.

  18. The Separation of Dysprosium and Holmium for Production of n.c.a. Ho-166

    Energy Technology Data Exchange (ETDEWEB)

    Choi, K. H.; Kim, J. B.; Park, U. J.; Nam, S. S.; Jang, K. D.; Yoo, K. M. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    The uses of radiolanthanide series are increasing in these days because of target therapy which does not require surgery. Certain radiolanthanides is very useful since they have the ability of simultaneous diagnosis and therapeutic effect in nuclear medicine. But this conventional therapeutic method has often limited by specific activity which is important things to affect labeling yield such as radiommunoconjugation and peptide labeling. There are two approaches to produce radiolanthanide in nuclear reactor. One is direct method using (n, γ) reaction and the other is indirect method using (n, γ)β reaction. Among the radiolanthanides, Ho-166 can be produced with two methods. Some radiolanthanides show the good theranostic effect in that they have proper LET (Linear Energy Transfer) to induce apoptosis for cancer treatment and gamma ray to use as a tracer for cancer diagnosis. The aim of this project based on this view is to get the carrier free radioisotopes for applying the nuclear medicine.

  19. Thermal expansion in dysprosium tungstate Dy10W2O21

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The complex oxide Dy10W2O21 was synthesized by a solid-state reaction and isolated in cubic symmetry by an X-ray diffractometry (XRD) method. Differential scanning calorimetry (DSC) measurements show that the compound is thermodynamically stable. The intrinsic thermal expansion coefficients were determined by extra-power powder Xray diffractometry from room temperature to 1000 ℃: linear coefficient α = 1.07 × 10-5 ℃-1 and bulk coefficient β=3.20 × 10-5℃-1. Dilatometry was used to measure the extrinsic thermal expansion coefficient (9.2 × 10-6℃-1).

  20. Magnetic Properties of Some Gadolinium, Erbium, Dysprosium, Manganese Substituted Samarium-2 Cobalt-17 Intermetallic Compounds.

    Science.gov (United States)

    1979-08-01

    S K AREA B WORK UNIT NUMBERSElect ronic Materials Research Division 61102AUS Army Electronics Technology & Devices Laborator) 1-rrr~ -rrd2An47 02 031...permanent magnet materials having intrinsically temperature compensated magneti- zations. The properties investigated were saturation magnetization...that excellent temperature compensation could be achieved in these compounds in the teinper~ture (cont’d) ~‘ DD I ? ) 1Q3 L°’TI°M °’ INOV BI

  1. Recycling of waste Nd-Fe-B sintered magnets by doping with dysprosium hydride nanoparticles

    Institute of Scientific and Technical Information of China (English)

    刘卫强; 李超; ZAKOTNIK Miha; 岳明; 张东涛; 黄秀莲

    2015-01-01

    Recycling of waste sintered Nd-Fe-B permanent magnets by doping DyH3 nanoparticles was investigated. The effect of the DyH3 nanoparticles on the microstructure and magnetic properties of the recycled magnets was studied. As the DyH3 nanoparticles additive increased, the coercivity of recycled magnet increased gradually. The recycled magnets with DyH3 nanoparticle content be-tween 0.0 wt.% and 1.0 wt.% maintained the remanence (Br), but, with higher additions, theBr began to decrease rapidly. The best recycled magnet produced contained 1.0 wt.% of DyH3 nanoparticles when compared to the properties of the starting waste sintering magnet. TheHcj,Br and (BH)max values of 101.7%, 95.4%, and 88.58%, respectively, were recovered.

  2. Photo and cathodoluminescence characteristics of dysprosium doped yttrium oxide nanoparticles prepared by Polyol method

    Energy Technology Data Exchange (ETDEWEB)

    Balderas-Xicohténcatl, R., E-mail: rbalderas@fis.cinvestav.mx [Centro de Investigación y de Estudios Avanzados-IPN, Departamento de Física, Apdo, Postal 14-470, Del. Gustavo A. Madero, C.P. 07360, México, D.F. (Mexico); Martínez-Martínez, R. [Instituto de Física y Matemáticas, Universidad Tecnológica de la Mixteca, Carretera a Acatlima Km. 2.5, Huajuapan de León, Oaxaca 69000 (Mexico); Rivera-Alvarez, Z.; Santoyo-Salazar, J.; Falcony, C. [Centro de Investigación y de Estudios Avanzados-IPN, Departamento de Física, Apdo, Postal 14-470, Del. Gustavo A. Madero, C.P. 07360, México, D.F. (Mexico)

    2014-02-15

    The luminescent characteristics of Dy{sup 3+}-doped Y{sub 2}O{sub 3} nanopowders synthesized using the polyol method are reported. The Y{sub 2}O{sub 3} nanoparticles presented a cubic phase crystalline structure of Y{sub 2}O{sub 3} after an annealing treatment in oxygen ambient at temperatures above 600 °C. The averaged crystallite size determined from the X-ray diffraction peaks width was in the 20–32 nm range depending on the annealing temperature. Scanning and transmission electron microscopy studies indicate the formation of nanoparticle aggregates up to 175 nm in diameter. Photoluminescence and cathodoluminescence measurements show a predominant emission at 573 nm, which is attributed to the {sup 4}F{sub 9/2}→{sup 6}H{sub 13/2} of the Dy{sup 3+} ion. The luminescence emission dependence with the dopant concentration and post-annealing temperatures is discussed. -- Highlights: • Nanoparticles of Y{sub 2}O{sub 3}:Dy{sup 3+} have been successfully synthesized by the polyol method. • XRD shows a grain size from 20 to 32 nm which is in agreement with SEM and TEM. • Electronic micrographs indicate the formation agglomerates of ∼175 nm. • The method used in the synthesis is industrial scalable and a low cost. • CL emission is observed at naked eye.

  3. Electronic structure, bulk and magnetic properties of MB{sub 6} and MB{sub 12} borides

    Energy Technology Data Exchange (ETDEWEB)

    Baranovskiy, A.E. [Institute for Low Temperature Physics and Engineering, NASU, Kharkov 61103 (Ukraine)]. E-mail: baranovskiy@ilt.kharkov.ua; Grechnev, G.E. [Institute for Low Temperature Physics and Engineering, NASU, Kharkov 61103 (Ukraine); Fil, V.D. [Institute for Low Temperature Physics and Engineering, NASU, Kharkov 61103 (Ukraine); Ignatova, T.V. [Institute for Low Temperature Physics and Engineering, NASU, Kharkov 61103 (Ukraine); Logosha, A.V. [Institute for Low Temperature Physics and Engineering, NASU, Kharkov 61103 (Ukraine); Panfilov, A.S. [Institute for Low Temperature Physics and Engineering, NASU, Kharkov 61103 (Ukraine); Svechkarev, I.V. [Institute for Low Temperature Physics and Engineering, NASU, Kharkov 61103 (Ukraine); Shitsevalova, N.Yu. [Institute for Problems of Materials Science, NASU, Kiev 03680 (Ukraine); Filippov, V.B. [Institute for Problems of Materials Science, NASU, Kiev 03680 (Ukraine); Eriksson, O. [Department of Physics, University of Uppsala, S-751 21 Uppsala (Sweden)

    2007-09-13

    The bulk and magnetic properties of MB{sub 6} and MB{sub 12} were investigated on the basis of first principles electronic structure calculations. The elastic constants were measured for ZrB{sub 12}, HoB{sub 12}, ErB{sub 12}, TmB{sub 12}, LuB{sub 12}, YB{sub 6} and LaB{sub 6} compounds at low temperatures. The calculated equations of states and balanced crystal orbital overlap populations have allowed to analyse bonding and magnetic properties of MB{sub 6} and MB{sub 12}.

  4. Multiple Electron Charge Transfer Chemistries for Electrochemical Energy Storage Systems: The Metal Boride and Metal Air Battery

    Science.gov (United States)

    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.

  5. Modification of Structure and Properties of Titanium Surfaces During Formation of Silicides and Borides Initiated by High-Energy Treatment

    Science.gov (United States)

    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.

  6. Enhanced Erosion Protection of TWAS Coated Ti6Al4V Alloy Using Boride Bond Coat and Subsequent Laser Treatment

    Science.gov (United States)

    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.

  7. Influence of the rare earth concentration on the crystallization process of Fe-Dy-B amorphous alloys. Study of Fe74Dy6B20 and Fe70Dy10B20 alloys

    Science.gov (United States)

    Ravach, G.; Machizaud, F.; Teillet, J.; LeBreton, J. M.; Fnidiki, A.

    2000-04-01

    The crystallization behaviour of Fe74 Dy6 B20 and Fe70 Dy10 B20 amorphous alloys was carefully investigated by differential scanning calorimetry, Mössbauer spectrometry and x-ray diffraction up to 800 °C. Calorimetric studies were performed in limited temperature ranges that were progressively extended. For Fe74 Dy6 B20 , after partial crystallization into the tetragonal Fe3 B compound, the remaining amorphous part segregates into two amorphous `phases', respectively enriched and impoverished in dysprosium. Tetragonal Fe3 B further transforms into orthorhombic Fe3 B. Metastable Dy3 Fe62 B14 compound then forms from the Dy-impoverished amorphous fraction, and subsequent crystallization of the Dy1 + icons/Journals/Common/varepsilon" ALT="varepsilon" ALIGN="MIDDLE"/> Fe4 B4 phase occurs in the Dy-enriched fraction. Finally, Dy3 Fe62 B14 decomposes into bcc iron, Dy1 + icons/Journals/Common/varepsilon" ALT="varepsilon" ALIGN="MIDDLE"/> Fe4 B4 and iron borides. The nature of the first crystallization product suggests the existence of local environments of t-Fe3 B type for this Dy concentration. The crystallization process of Fe70 Dy10 B20 strongly differs from that of Fe74 Dy6 B20 . Segregation phenomena occur in the amorphous state prior to any crystallization. If the nature of the first crystallization product is assumed to be correlated with short-range order in the amorphous state, our results suggest that the local environments differ from those of Fe74 Dy6 B20 , as they probably involve dysprosium atoms. This behaviour would agree with a previous Mössbauer study performed on the as-quenched amorphous alloys, providing evidence for a structural modification of the iron environments in the rare earth concentration range 8-9 at.%.

  8. Characterization of high-temperature oxide films on dysprosium-doped Fe-20Cr alloys by electrochemical techniques

    Institute of Scientific and Technical Information of China (English)

    GUO Pingyi; ZENG Chaoliu; SHAO Yong; QIN Zeshang

    2012-01-01

    The oxidation propegies of Fe-20Cr,Fe-20Cr-0.2Dy and Fe-20Cr-1Dy alloys were studied using gravimetric and electrochemical techniques.The high-temperature oxide films of Dy-doped Fe-20Cr alloys were prepared in air at 900 ℃ for 24,48 and 100 h,respectively.The electrochemical experiment was performed by a three-electrode electrochemical cell and in 0.1 mol/L Na2SO4 aqueous solution.Proper models were built for describing electrochemical impedance spectroscopy of the different oxide layers and the spectra were interpreted in terms of a two-layer model of the films.The results revealed that the oxide films of Dy-doped Fe-20Cr alloys became compacter than that of undoped alloys and retained their good protective ability for a relatively long time.With increasing content of Dy,the protection of the oxide films slightly decreased.Mott-Schottky curves indicated that all the oxides were n-type semi-conductors,and the Nd value of oxide film on Fe-20Cr was much larger than that of Dy-doped Fe-20Cr alloys.The results of kinetic curves and SEM were in agreement with electrochemical impedance spectroscopy and Mott-Schottky data.

  9. Reexamination of Nuclear Shape Transitions in Gadolinium and Dysprosium Isotopes Chains by Using the Geometric Collective Model

    Directory of Open Access Journals (Sweden)

    Khalaf A. M.

    2014-01-01

    Full Text Available The critical points of potential energy surface (PES’s of the limits of nuclear struc- ture harmonic oscillator, axially symmetric rotor and deformed -soft and discussed in framework of the general geometric collective model (GCM. Also the shape phase transitions linking the three dynamical symmetries are studied taking into account only three parameters in the PES’s. The model is tested for the case of 238 92 U , which shows a more prolate behavior. The optimized model parameters have been adjusted by fit- ting procedure using a simulated search program in order to reproduce the experimental excitation energies in the ground state band up to 6 + and the two neutron separation energies.

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

    Science.gov (United States)

    2015-01-01

    yttrium are often used for pigmentation for consumer products such as paint and sunglasses. REE-based lasers are used for cosmetic, epidermal, and... bacterial cell walls (Takahashi 2005). In acidic solutions, from an initial concentration of 100 micrograms of an REE mixture per liter, the bacteria...Logistics Agency Justification Book , Research, Development, Test, and Evaluation, Defense-Wide,” U.S. Department of Defense, Washington, DC: 2013

  11. Influence of dysprosium addition on the structural, morphological, electrical and magnetic properties of nano-crystalline W-type hexaferrites

    Indian Academy of Sciences (India)

    Ali-Sharbati; Javad-Mola Verdi Khani; G R Amiri; R Mousarezaei

    2015-02-01

    Dysporium (Dy)-substituted W-type barium hexaferrites were prepared by the citrate sol–gel-method. Crystalline structure, morphology, magnetic properties, DC resistivity and microwave absorption properties of BaNi2DyFe16−O27 ( = 0-0.9) were studied using X-ray diffraction, transmission electron microscope (TEM), vibrating sample magnetometer and vector network analyzer and sensitive source meter, respectively. Single-phase W-type barium hexaferrites, with a chemical composition of BaNi2DyFe16−O27 ( = 0-0.9), were formed by being heated at 1250°C for 4 h in air. The magnetic properties such as saturation magnetization (s), and coercivity (c) were calculated from hysteresis loops. Hysteresis loop measurements show that the coercivity values lie in the range of 530–560 Oe with increasing Dy content. It was also observed that magnetization decreases with the increase of Dy content. The DC resistivity was observed to increase from 0.83 × 107 to 6.92 × 107 cm with increasing Dy contents due to the unavailability of Fe3+ ions. Microwave absorption properties of hexaferrite (70 wt%)–acrylic resin (30 wt%) composites were measured by the standing-wave-ratio (SWR) method in the range from 12 to 20 GHz. For sample with = 0.6, a minimum reflection loss of −40 dB was obtained at 16.2 GHz for a layer of 1.7 mm in thickness. Sample with = 0.9 had wide bandwidth absorption in the frequency range of 13.5–18 GHz with reflection losses less than −15 dB. Meanwhile the minimum reflection point shifts toward higher frequency with the increase of Dy content.

  12. L-Shell Ionization Cross Section Measurements of Dysprosium and Samarium by Low-Energy Electron Impact

    Institute of Scientific and Technical Information of China (English)

    GOU Cheng-Jun; WU Zhang-Wen; YANG Dai-Lun; HE Fu-Qing; PENG Xiu-Feng; AN Zhu; LUO Zheng-Ming

    2005-01-01

    @@ The Lα, Lβ and Lγ x-ray production cross sections of Dy and Sm by electron impact are measured at energies from near threshold to tens of keV. In the experiments, thin targets with thick substrates are used. Meanwhile,the electron transport bipartition model is used to eliminate the influence of electrons reflected from the thick substrates on measurements. The measured x-ray production cross sections are also compared with the theoretical predictions by Gryzinski and McGuire.

  13. Generation of White Light from Dysprosium-Doped Strontium Aluminate Phosphor by a Solid-State Reaction Method

    Science.gov (United States)

    Sahu, Ishwar Prasad; Bisen, D. P.; Brahme, N.; Tamrakar, Raunak Kumar

    2016-04-01

    A single-host lattice, white light-emitting SrAl2O4:Dy3+ phosphor was synthesized by a solid-state reaction method. The crystal structure of prepared SrAl2O4:Dy3+ phosphor was in a monoclinic phase with space group P21. The chemical composition of the sintered SrAl2O4:Dy3+ phosphor was confirmed by the energy dispersive x-ray spectroscopy technique. Under ultra-violet excitation, the characteristic emissions of Dy3+ are peaking at 475 nm, 573 nm and 660 nm, originating from the transitions of 4F9/2 → 6H15/2, 4F9/2 →&!nbsp; 6H13/2 and 4F9/2 → 6H11/2 in the 4f9 configuration of Dy3+ ions. Commission International de I'Eclairage color coordinates of SrAl2O4:Dy3+ are suitable for white light-emitting phosphor. In order to investigate the suitability of the samples as white color light sources for industrial uses, correlated color temperature (CCT) and color rendering index (CRI) values were calculated. Values of CCT and CRI were found well within the defined acceptable range. Mechanoluminescence (ML) intensity of SrAl2O4:Dy3+ phosphor increased linearly with increasing impact velocity of the moving piston. Thus, the present investigation indicates piezo-electricity was responsible for producing ML in sintered SrAl2O4:Dy3+ phosphor. Decay rates of the exponential decaying period of the ML curves do not change significantly with impact velocity. The photoluminescence and ML results suggest that the synthesized SrAl2O4:Dy3+ phosphor was useful for the white light-emitting diodes and stress sensor respectively.

  14. Significant enhancement of energy barriers in dinuclear dysprosium single-molecule magnets through electron-withdrawing effects.

    Science.gov (United States)

    Habib, Fatemah; Brunet, Gabriel; Vieru, Veacheslav; Korobkov, Ilia; Chibotaru, Liviu F; Murugesu, Muralee

    2013-09-11

    The effect of electron-withdrawing ligands on the energy barriers of Single-Molecule Magnets (SMMs) is investigated. By introducing highly electron-withdrawing atoms on targeted ligands, the energy barrier was significantly enhanced. The structural and magnetic properties of five novel SMMs based on a dinuclear {Dy2} phenoxo-bridged motif are explored and compared with a previously studied {Dy2} SMM (1). All complexes share the formula [Dy2(valdien)2(L)2]·solvent, where H2valdien = N1,N3-bis(3-methoxysalicylidene) diethylenetriamine, the terminal ligand L = NO3(-) (1), CH3COO(-) (2), ClCH2COO(-) (3), Cl2CHCOO(-) (4), CH3COCHCOCH3(-) (5), CF3COCHCOCF3(-) (6), and solvent = 0.5 MeOH (4), 2 CH2Cl2 (5). Systematic increase of the barrier was observed for all complexes with the most drastic increase seen in 6 when the acac ligand of 5 was fluorinated resulting in a 7-fold enhancement of the anisotropic barrier. Ab initio calculations reveal more axial g tensors as well as higher energy first excited Kramers doublets in 4 and 6 leading to higher energy barriers for those complexes.

  15. Slow Magnetic Relaxation Observed in Dysprosium Compounds Containing Unsupported Near-Linear Hydroxo- and Fluoro-Bridges.

    Science.gov (United States)

    Brunet, Gabriel; Habib, Fatemah; Korobkov, Ilia; Murugesu, Muralee

    2015-07-06

    The encapsulating N1,N3-bis(3-methoxysalicylidene)diethylenetriamine (H2valdien) ligand was employed to isolate two novel Dy(III) compounds which contain rare bridging pathways for lanthanide systems. Compound 1, [Na2Dy(III)2(valdien)2(μ-OH)(dbm)2(H2O)2][Na2Dy(III)2(valdien)2(μ-OH)(NO3)2(dbm)2], where dbm(-) is dibenzoylmethanido, and compound 2, [Na3Dy(III)2(valdien)2(μ-F)(μ3-F)2(Cl)2(MeOH)2]n·0.5(MeOH)·(H2O), both exhibit linear lone hydroxo- and fluoro-bridges, respectively, between the metal centers. The unit cell of 1 comprises two discrete dinuclear molecules, which differ slightly, forming a cation-anion pair, while 2 forms a coordination polymer. The magnetic investigations indicate that both compounds display ferromagnetic coupling between the Dy(III) ions. Magnetic susceptibility measurements in the temperature range 1.8-300 K reveal that the Dy(III) ions in 1 are weakly coupled, resulting in a mononuclear single-molecule magnet-like behavior under an applied field. In the case of 2, the stronger coupling arising from the fluoride-bridge, leads to zero-field single-molecule magnet (SMM) behavior with a non-negligible anisotropy barrier (Ueff) of 42 K.

  16. Effect of Ligand Field Tuning on the SMM Behavior for Three Related Alkoxide-Bridged Dysprosium Dimers.

    Science.gov (United States)

    Peng, Yan; Mereacre, Valeriu; Baniodeh, Amer; Lan, Yanhua; Schlageter, Martin; Kostakis, George E; Powell, Annie K

    2016-01-04

    The synthesis and characterization of three Dy2 compounds, [Dy2(HL1)2(NO3)4] (1), [Dy2(L2)2(NO3)4] (2), and [Dy2(HL3)2(NO3)4] (3), formed using related tripodal ligands with a central tertiary amine bearing picolyl and alkoxy arms, 2-[(2-hydroxy-ethyl)-pyridin-2-ylmethylamino]-ethanol (H2L1), 2-(bis-pyridin-2-ylmethylamino)-ethanol (HL2), and 2-(bis-pyridin-2-ylmethylamino)-propane-1,3-diol (H2L3), are reported. The compounds are rare examples of alkoxide-bridged {Dy2} complexes and display capped square antiprism coordination geometry around each Dy(III) ion. Changes in the ligand field environment around the Dy(III) ions brought about through variations in the ligand donors can be gauged from the magnetic properties, with compounds 1 and 2 showing antiparallel coupling between the Dy(III) ions and 3 showing parallel coupling. Furthermore, slow relaxation of the magnetization typical of SMM behavior could be observed for compounds 2 and 3, suggesting that small variations in the ligand field can have a significant influence on the slow relaxation processes responsible for SMM behavior of Dy(III)-based systems.

  17. Effects of magnetic annealing on structure and multiferroic properties of pure and dysprosium substituted BiFeO 3

    KAUST Repository

    Zhang, Shuxia

    2012-07-01

    In this work, the effects of magnetic annealing on crystal structure and multiferroic properties of BiFeO 3 and Bi 0.85Dy 0.15FeO 3 have been investigated. It is found that the X-ray diffraction patterns of pure BiFeO 3 samples are obviously broadened after magnetic annealing, whereas those of Bi 0.85Dy 0.15FeO 3 samples are almost unchanged. Magnetic field annealing did not affect the magnetic properties of these two kinds of samples much. However, ferroelectric properties of the two materials exhibited different behaviors after magnetic field annealing. For pure BiFeO 3 samples, the remnant polarizations (P r) are suppressed; in contrast, for Bi 0.85Dy 0.15FeO 3 samples, P r is greatly enhanced. Possible mechanisms for the effects of magnetic field annealing have been discussed. © 2012 Elsevier B.V. All rights reserved.

  18. Dielectric relaxation in double potassium yttrium orthophosphate K 3Y(PO 4) 2 doped by praseodymium and dysprosium ions

    Science.gov (United States)

    Szulia, S.; Kosmowska, M.; Kołodziej, H. A.; Mizer, D.; Czupińska, G.

    2011-12-01

    We report the paper presents the results of electric properties of double potassium yttrium orthophosphates doped by lanthanide ions K 3Y( 1-x)Ln x(PO 4) 2 ( x = 0.01, 0.05, Ln = Pr 3+, Dy 3+). Electric permittivity and dielectric loss measurements have been performed on polycrystalline samples in the temperature range -50-120 °C and frequency range 1 kHz-1 MHz by means of HP 4282A impedance meter. The frequency and temperature dependence of electric properties were analyzed by theoretical models of dielectric relaxation in order to obtain information abut molecular dynamic of our solids in external electric field.

  19. Dilution-induced slow magnetic relaxation and anomalous hysteresis in trigonal prismatic dysprosium(III) and uranium(III) complexes.

    Science.gov (United States)

    Meihaus, Katie R; Rinehart, Jeffrey D; Long, Jeffrey R

    2011-09-05

    Magnetically dilute samples of complexes Dy(H(2)BPz(Me2)(2))(3) (1) and U(H(2)BPz(2))(3) (3) were prepared through cocrystallization with diamagnetic Y(H(2)BPz(Me2)(2))(3) (2) and Y(H(2)BPz(2))(3). Alternating current (ac) susceptibility measurements performed on these samples reveal magnetic relaxation behavior drastically different from their concentrated counterparts. For concentrated 1, slow magnetic relaxation is not observed under zero or applied dc fields of several hundred Oersteds. However, a 1:65 (Dy:Y) molar dilution results in a nonzero out-of-phase component to the magnetic susceptibility under zero applied dc field, characteristic of a single-molecule magnet. The highest dilution of 3 (1:90, U:Y) yields a relaxation barrier U(eff) = 16 cm(-1), double that of the concentrated sample. These combined results highlight the impact of intermolecular interactions in mononuclear single-molecule magnets possessing a highly anisotropic metal center. Finally, dilution elucidates the previously observed secondary relaxation process for concentrated 3. This process is slowed down drastically upon a 1:1 molar dilution, leading to butterfly magnetic hysteresis at temperatures as high as 3 K. The disappearance of this process for higher dilutions reveals it to be relaxation dictated by short-range intermolecular interactions, and it stands as the first direct example of an intermolecular relaxation process competing with single-molecule-based slow magnetic relaxation.

  20. Challenging lanthanide relaxation theory: erbium and thulium complexes that show NMR relaxation rates faster than dysprosium and terbium analogues.

    Science.gov (United States)

    Funk, Alexander M; Harvey, Peter; Finney, Katie-Louise N A; Fox, Mark A; Kenwright, Alan M; Rogers, Nicola J; Senanayake, P Kanthi; Parker, David

    2015-07-07

    Measurements of the proton NMR paramagnetic relaxation rates for several series of isostructural lanthanide(III) complexes have been performed in aqueous solution over the field range 1.0 to 16.5 Tesla. The field dependence has been modeled using Bloch-Redfield-Wangsness theory, allowing values for the electronic relaxation time, Tle and the magnetic susceptibility, μeff, to be estimated. Anomalous relaxation rate profiles were obtained, notably for erbium and thulium complexes of low symmetry 8-coordinate aza-phosphinate complexes. Such behaviour challenges accepted theory and can be interpreted in terms of changes in Tle values that are a function of the transient ligand field induced by solvent collision and vary considerably between Ln(3+) ions, along with magnetic susceptibilities that deviate significantly from free-ion values.

  1. Distance determination from dysprosium induced relaxation enhancement: a case study on membrane-inserted WALP23 polypeptides

    NARCIS (Netherlands)

    Lueders, P.; Razzaghi, S.; Jäger, H.; Tschaggelar, R.; Hemminga, M.A.; Yulikov, M.; Jeschke, G.

    2013-01-01

    Membrane incorporated synthetic a-helical polypeptides labelled with Dy(III) chelate complexes and nitroxide radicals were studied by the inversion recovery (IR) technique and Dy(III)-nitroxide distances were obtained. A comparison of obtained distances with the previously reported Gd(III)-nitroxide

  2. Effect of borate coating on corrosion resistance of pure nickel in molten LiCl-Li2O

    Institute of Scientific and Technical Information of China (English)

    刘瑞岩; 王旭; 张俊善; 王秀敏; 祝美丽

    2004-01-01

    The pack boriding process was used to treat pure nickel at a boriding temperature of 950 ℃ for a boriding time of 5 h. A dense and continuous borided layer with 40 μm thickness was obtained on pure nickel. Corrosion behavior of the borided layer was investigated in molten LiCl-10% Li2O(mass fraction) at 750 ℃ in air. The mass lower than that of unborided pure nickel. The preferential corrosion of B in borided layer effectively prevents the corrosion of nickel, which improves the corrosion resistance of pure nickel in molten LiCl-Li2 O.

  3. Diffusional Growth Kinetics Analisys of Fe2B Layers Applied During the Coating Powder-Pack Boriding Process on an AISI 1026 Steel

    Directory of Open Access Journals (Sweden)

    M. Elias-Espinosa

    2015-01-01

    Full Text Available La exigencia de emplear materiales con propiedades avanzadas incluyen la necesidad de aplicar recubrimientos de alta resistencia que alarguen la vida de útil de aceros comerciales, de esta forma, el tratamiento termoquímico de borurización tiene el potencial para cumplir estos requerimientos. En este trabajo de investigación se formula un modelo matemático para analizar la cinética de crecimiento de las capas de 2 Fe B formadas sobre la superficie de un acero AISI 1026. El modelo matemático propuesto se desarrolló en base a la solución de la ecuación de balance de masa de la interface de crecimiento 2 Fe B/Fe para evaluar el coeficiente de difusión del boro a través de las capas de Fe2B en un rango de temperaturas de 1123 a1273 K. En el modelo desarrollado se incluyó el tiempo de incubación del boruro para formar la fase Fe2B. El modelo matemático fue validado con datos experimentales realizados a una temperatura de 1253 K y tiempo de siete horas. Las capas de boruro fueron caracterizadas y analizadas por microscopia óptica y de barrido (se obtuvo un EDS, así como por Difracción de Rayos – X (XRD. Se utilizó la técnica de indentación Daimler-Benz Rockwell-C para evaluar cualitativamente la adherencia de la capa de Fe2B sobre el sustrato (acero AISI 1026. Para usos prácticos y para un espesor determinado, se propuso un diagrama a espesor constante (215 μm el cual es controlado con la variación de la temperatura y tiempo de exposición al recubrimiento. De los resultados obtenidos, se encontró que la energía de activación para el boro en el acero AISI 1026 es igual a 178 kJ mol-1.

  4. LiB12PC, the first boron-rich metal boride with phosphorus--synthesis, crystal structure, hardness, spectroscopic investigations.

    Science.gov (United States)

    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. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Diffusional Growth Kinetics Analisys of Fe2B Layers Applied During the Coating Powder-Pack Boriding Process on an AISI 1026 Steel

    OpenAIRE

    2015-01-01

    La exigencia de emplear materiales con propiedades avanzadas incluyen la necesidad de aplicar recubrimientos de alta resistencia que alarguen la vida de útil de aceros comerciales, de esta forma, el tratamiento termoquímico de borurización tiene el potencial para cumplir estos requerimientos. En este trabajo de investigación se formula un modelo matemático para analizar la cinética de crecimiento de las capas de 2 Fe B formadas sobre la superficie de un acero AISI 1026. El modelo matemático p...

  6. Peculiarities of structure state and mechanical characteristics in ion-plasma condensates of quasibinary system borides W2B5-TiB2

    Directory of Open Access Journals (Sweden)

    Sobol O.V.

    2006-01-01

    Full Text Available In order to create high-durable, wear-resistant materials for a wide range of functional applications, comparative investigations of the structure and mechanical characteristics of ion-plasma Ti-W-B nano-crystalline condensates were carried out. The range of condensation rates 0.11÷0.25nm/s was found to be critical for the coatings obtained from the target with 80 vol% W2B5-20 vol% TiB2. Below this, a phase with a cubic lattice (W,TiB0.7…1.2(O,N,C0.3…0.2 formed, while over this range, a solid solution (W,TiB2 with a hexagonal lattice and element composition close to the sputtered target was observed. The structure state of the material changed from cluster-crystalline (under low sputter potentials U=0.6…1.0 kV to textured- crystalline (under U>2.2 kV. Structure perfection improvement with U increase results in higher hardness and elastic modulus of condensates. The conditions of cluster component formation and its effect on hardness and elastic modulus of condensates are discussed. .

  7. Preparation and Characterization of Zirconium Boride Precursor Fiber%二硼化锆陶瓷前驱体纤维的制备及表征

    Institute of Scientific and Technical Information of China (English)

    贾军; 孙泽玉; 耿冉; 胡建建; 韩克清; 余木火

    2013-01-01

    In this paper,ZrOCl2·8H2O,boric acid,sucrose,citric acid were used as inorganic substances,ZrB2 precursor solution was prepared via the mixing of inorganic and PVA,precursor fibers were obtained through dry spinning.Microstructure was observed by SEM,reactions and series changes were studied by FT-IR,DSC and TG.The results showed reactions happened among inorganic substances and polyvinyl alcohol and PVA stabilized owing to these reactions.The precursor fiber showed a smooth and intact appearance and provided a basic study for the preparation of ZrB2 ceramic fibers.%利用八水合氧氯化锆、硼酸、蔗糖和柠檬酸为无机原料,聚乙烯醇为有机原料,采用有机、无机共混反应制得前驱体溶液,并利用干法纺丝制得前驱体纤维,通过红外光谱(IR)、差示扫描(DSC)、热失重(TG)分析表征发生的反应及产生的一系列变化,利用扫描电镜(SEM)观察纤维的形态结构.结果表明:无机成分与聚乙烯醇发生了反应并使聚乙烯醇变得稳定,制得了光滑致密的纤维,为下一步制得ZrB2陶瓷纤维做好了准备.

  8. Diffusional Growth Kinetics Analisys of Fe2B Layers Applied During the Coating Powder-Pack Boriding Process on an AISI 1026 Steel

    OpenAIRE

    M. Elias-Espinosa; J. Zuno-Silva; M. Ortiz-Domínguez; J. Hernández-Ávila; O. Damián-Mejía

    2015-01-01

    La exigencia de emplear materiales con propiedades avanzadas incluyen la necesidad de aplicar recubrimientos de alta resistencia que alarguen la vida de útil de aceros comerciales, de esta forma, el tratamiento termoquímico de borurización tiene el potencial para cumplir estos requerimientos. En este trabajo de investigación se formula un modelo matemático para analizar la cinética de crecimiento de las capas de 2 Fe B formadas sobre la superficie de un acero AISI 1026. El modelo matemático p...

  9. Influence of dysprosium substitution on magnetic and mechanical properties of high intrinsic coercivity Nd-Fe-B magnets prepared by double-alloy powder mixed method

    Institute of Scientific and Technical Information of China (English)

    胡志华; 瞿海锦; 马冬威; 罗成; 王会杰

    2016-01-01

    The double-alloy powder mixed method is very proper for developing new small-mass products by changing the composi-tion of sintered Nd-Fe-B magnets, and there is little research on this aspect. The variation on magnetic and mechanical properties of high intrinsic coercivity Nd-Fe-B magnets prepared by double-alloy powder mixed method was discussed, which is a method blend-ing two-type main phase alloy powders with different components. The results showed that the intrinsic coercivity and density of sin-tered Nd-Fe-B magnets increased gradually with the increase in Dy content, and the double-alloy powder mixed method could obtain high intrinsic coercivity Nd-Fe-B magnets with good crystallographic alignment and microstructure. The bending strength of sintered Nd-Fe-B magnets declined, and the Rockwell hardness of sintered Nd-Fe-B magnets first declined, and then increased with the in-crease in Dy content. The microstructure showed that there existed the phenomenon that the Dy element diffused into main phase dur-ing sintering process, and the distribution of Dy content in main phase had some variation in homogeneity as a result of incomplete reaction between the double-alloy powder types.

  10. Effect of dysprosium substitution on electrical properties of SrBi{sub 4}Ti{sub 4}O{sub 15}

    Energy Technology Data Exchange (ETDEWEB)

    Mamatha, B., E-mail: boinanemamatha@gmail.com; Sarah, P.

    2014-10-15

    SrBi{sub 4−x}Dy{sub x}Ti{sub 4}O{sub 15} (with x = 0.02, 0.04, 0.06 and 0.08) powders have been synthesized using the stoichiometric amounts of nitrates and oxides of the constituent materials through sol–gel method. The compound so formed is characterized using X-ray diffraction. The density and lattice parameters are calculated. The impedance and electrical conductivity properties are investigated. The imaginary part of impedance as a function of frequency shows Debye like relaxation. Impedance data presented in the Nyquist plot which is used to identify an equivalent circuit and the fundamental circuit parameters are determined at different temperatures. The results of bulk a.c. conductivity as a function of frequency at different temperatures are presented. The dielectric behavior was investigated. Permittivity was calculated based on the relaxation frequency using an alternative approach based on the variation of the imaginary impedance component as a function of reciprocal angular frequency. The frequency dependence of real and imaginary permittivities was also investigated. - Highlights: • SrBi{sub 4−x}Dy{sub x}Ti{sub 4}O{sub 15} (x = 0.02, 0.04, 0.06 and 0.08) powders are produced by sol–gel method. Phase formation is confirmed by XRD analysis. • Frequency dependent imaginary part of impedance shows distribution of relaxation in system. • Broadness of Z″ peak shows distribution of relaxation frequency. • Increase in peak width at ½ maxima of Z″ with increase of temperature shows increase of relaxation frequency distribution. • Cole–Cole plots are resolved into two different circles, ascribed to different mechanisms of polarization and relaxation phenomena.

  11. Hexanuclear, heterometallic, Ni₃Ln₃ complexes possessing O-capped homo- and heterometallic structural subunits: SMM behavior of the dysprosium analogue.

    Science.gov (United States)

    Goura, Joydeb; Guillaume, Rogez; Rivière, Eric; Chandrasekhar, Vadapalli

    2014-08-04

    The reaction of hetero donor chelating mannich base ligand 6,6'-{(2-(dimethylamino)ethylazanediyl)bis(methylene)}bis(2-methoxy-4-methylphenol) with Ni(ClO4)2·6H2O and lanthanide(III) salts [Dy(III) (1); Tb(III) (2); Gd (III) (3); Ho(III) (4); and Er(III) (5)] in the presence of triethylamine and pivalic acid afforded a series of heterometallic hexanuclear Ni(II)-Ln(III) coordination compounds, [Ni3Ln3(μ3-O)(μ3-OH)3(L)3(μ-OOCCMe3)3]·(ClO4)·wCH3CN·xCH2Cl2·yCH3OH·zH2O [for 1, w = 8, x = 3, y = 0, z = 5.5; for 2, w = 0, x = 5, y = 0, z = 6.5; for 3, w = 15, x = 18, y = 3, z = 7.5; for 4, w = 15, x = 20, y = 6, z = 9.5; and for 5, w = 0, x = 3, y = 2, z = 3]. The molecular structure of these complexes reveals the presence of a monocationic hexanuclear derivative containing one perchlorate counteranion. The asymmetric unit of each of the hexanuclear derivatives comprises the dinuclear motif [NiLn(L)(μ3-O)(μ3-OH)(μ-Piv)]. The cation contains three interlinked O-capped clusters: one Ln(III)3O and three Ni(II)Ln(III)2O. Each of the lanthanide centers is eight- coordinated (distorted trigonal-dodecahedron), while the nickel centers are hexacoordinate (distorted octahedral). The study of the magnetic properties of all compounds are reported and suggests single molecule magnet behavior for the Dy(III) derivative (1).

  12. Two-dimensional dysprosium(III triiodate(V dihydrate, Dy(IO33(H2O·H2O

    Directory of Open Access Journals (Sweden)

    Laishun Qin

    2009-08-01

    Full Text Available During our research into novel nonlinear optical materials using 1,10-phenanthroline as an appending ligand on lanthanide iodates, crystals of an infinite layered DyIII iodate compound, Dy(IO33(H2O·H2O, were obtained under hydrothermal conditions. The DyIII cation has a dicapped trigonal prismatic coordination environment consisting of one water O atom and seven other O atoms from seven iodate anions. These iodate anions bridge the DyIII cations into a two-dimensional structure. Through O—H...O hydrogen bonds, all of these layers stack along [111], giving a supramolecular channel, with the solvent water molecules filling the voids.

  13. Two-dimensional dysprosium(III) triiodate(V) dihydrate, Dy(IO3)3(H2O)·H2O

    Science.gov (United States)

    Chai, Wenxiang; Song, Li; Shi, Hongsheng; Qin, Laishun; Shu, Kangying

    2009-01-01

    During our research into novel nonlinear optical materials using 1,10-phenanthroline as an appending ligand on lanthanide iodates, crystals of an infinite layered DyIII iodate compound, Dy(IO3)3(H2O)·H2O, were obtained under hydro­thermal conditions. The DyIII cation has a dicapped trigonal prismatic coordination environment consisting of one water O atom and seven other O atoms from seven iodate anions. These iodate anions bridge the DyIII cations into a two-dimensional structure. Through O—H⋯O hydrogen bonds, all of these layers stack along [111], giving a supra­molecular channel, with the solvent water mol­ecules filling the voids. PMID:21583297

  14. 吡罗昔康镝配合物的合成与表征%Synthesis and characterization of the complex of piroxicam and dysprosium

    Institute of Scientific and Technical Information of China (English)

    张艳军; 石俊; 孙体健; 徐隋意; 曹晓峰

    2009-01-01

    利用热乙醇搅拌法合成吡罗昔康和稀土金属镝的配合物,通过紫外光谱、红外光谱、元素分析、电导率、差热-热重等方法对其进行表征,最后确定其组成为Dy(pir)2C2H5OHCl3·2H2O.

  15. Multicolor photoluminescence and energy transfer properties of dysprosium and europium-doped Gd{sub 2}O{sub 3} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yanxia; Liu, Guixia, E-mail: liuguixia22@163.com; Wang, Jinxian; Dong, Xiangting; Yu, Wensheng

    2015-11-15

    In this study, a series of Gd{sub 2}O{sub 3}: Ln{sup 3+} (Ln = Dy, Eu) submicrospheres were successfully prepared by a hydrothermal method and a subsequent higher temperature pyrolysis. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectrometer (EDS), photoluminescence (PL) spectra and vibrating sample magnetometer (VSM) were utilized to characterize the as-prepared samples. The precursor sample thoroughly decomposed into Gd{sub 2}O{sub 3} submicrospheres with a diameter of about 550 nm after calcination. Under UV excitation, the samples exhibit multicolor emissions including yellow-green, yellow, red as well as white, moreover, the Dy{sup 3+} ions acted as donors can transfer the energy to Eu{sup 3+} served as acceptors in Gd{sub 2}O{sub 3}: Dy{sup 3+}, Eu{sup 3+} system. The interaction between Dy{sup 3+} ions and Eu{sup 3+} ions is verified to be phonon-assisted electric quadrupole–quadrupole interaction. Multicolor luminescence including white light emission can be obtained through varying the content of Eu{sup 3+} or adopting different excitation wavelengths in Dy{sup 3+} and Eu{sup 3+} co-doped Gd{sub 2}O{sub 3} system. The energy transfer efficiency reaches 88.2% when the doped concentration of Eu{sup 3+} is 0.035. The CIE chromaticity diagram directly reveals the variability of the hue of the as-prepared samples. Besides, the as-prepared samples exhibit paramagnetic properties at room temperature. This type of color-tunable luminescence phosphors has promising applications in the fields of photoelectronic devices and biomedical science. - Graphical abstract: Tunable multicolor emissions and energy transfer properties of lanthanides (Ln{sup 3+}, Ln{sup 3+} = Dy{sup 3+}, Eu{sup 3+}) doped cubic Gd{sub 2}O{sub 3} submicrospheres prepared by hydrothermal method and a subsequent calcination. - Highlights: • The as-prepared samples can exhibit multicolor emissions. • Dy{sup 3+} transfer energy to Eu{sup 3+} in Dy{sup 3+} and Eu{sup 3+} co-doped Gd{sub 2}O{sub 3}. • The as-prepared phosphor has promising applications in the fields of photoelectronic devices and biomedical science.

  16. Emission from Divalent Dysprosium (Dy2+ )in Crystalline Strontium Tetraborate%晶态四硼酸锶中二价镝的发射

    Institute of Scientific and Technical Information of China (English)

    许武; Peterson; J; R

    2001-01-01

    Emission spectra from SrB4O7 doped with Dy2O3 and heated in air have been recorded at room temperature. A change in oxidation state from Dy3+ to Dy2+ was observed. Optimum production of Dy2+ ion occurs when the sample is heated in air at about 650℃. Two broad emission bands centered in the vicinity of 550 and 660nm have been observed from the sample under the excitation of 457.9nm. It is suggested that these bands are due to Dy2 + ion emission from the 5d band into the ground state 4f level (5I8). Several conditions promoting the reduction of Dy3+ion in this matrix are discussed. To aid the reduction of Dy3+ ion, we have also prepared SrB4O7 doped with Dy2O3 in Ar/H2 (4 % ) atmosphere and compared the optical characteristics of Dy2 + ion in these samples with those from the samples prepared in air. The range of g-element reducibility and stabilization in SrB4O7 has been extended from Tm2+[ E0 (Tm3+/Tm2+) = -2.3V] to Dy2+ [E0(Dy3+/Dy2 +) = -2.6V] in the present work; however, the limit of this facile reduction process has not been determined yet.%在室温下测量了在空气中灼烧掺杂Dy2O3的SrB4O7的发射光谱.观测到了由Dy3+到Dy2+氧化态的变化.经优化,当在空气中灼烧温度为650℃时为产生Dy2+的最佳温度.在457.9nm的激发下测出了两个峰位分别位于550和660nm的宽发射带.我们认为这两个宽发射带是由Dy2+离子由5d态向4f基态能级(5I8)跃迁产生的.讨论了几个有益于在这种基质中还原Dy3+离子的条件.为了实现Dy3+离子的还原,我们还在Ar/H2(4%)气氛中制备了Dy2O3掺杂的SrB4O7,比较了这种样品和在空气中所制备的样品的光学特性.本文还对标志SrB4O7还原性和稳定性的g-因子由Tm2+的[Eo(Tm3+/Tm2+=-2.3V]推导出Dy2+的[E0(Dy3+/Dy2+)=-2.6V],但对这种还原过程的局限性尚未确定.

  17. CCDC 1402057: Experimental Crystal Structure Determination : pentakis(tetra-n-butylammonium) tetrakis(mu-oxalato)-dodecachloro-tetranitrosyl-ethanol-tetra-ruthenium-dysprosium sesquihydrate

    KAUST Repository

    Kuhn, Paul-Steffen

    2015-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  18. 渗硼

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Development and practical application of boride as engineering ceramics;Development and practical application of boride as engineering ceramics; Effect of boron micro-alloying on microstructure and mechanical properties of fine-grained CM247LC superalloy; Effects of metallic elements on thermoelectric properties of silicon borides

  19. Activation of Small Molecules by DyI_2 and Dy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    1 Results The reactivities of dysprosium diiodide and metallic dysprosium toward small molecules are discussed.For instance,DyI2-induced silyl radical reactions are described.The combination of dysprosium diiodide and dichloromethane can serve as an effective methylene transfer reagent for cyclopropanation of unfunctionalized alkenes beyond that possible with other metal-dichloromethane systems.Furthermore,we report that the combination of chlorosilane and metallic Dy can also serve as an effective prom...

  20. Formation and growth model of B-Al permeation layer of Steel 45

    Institute of Scientific and Technical Information of China (English)

    吉泽升; 李庆芬; 李冬华

    2002-01-01

    The B-Al permeation layers of Steel 45 were studied by means of SEM, TEM and XRD. The formation and growth model of permeation layer was proposed. The layer formation, growth and the migration behaviors of B were discussed. It is suggested that the diffusion of Al is deferred when the surface was covered by borides and aluminize compounds are surrounded by borides with the further growing of borides.

  1. Heterometallic octanuclear RE(III)3Ni(II)5 (RE = Dy(III), Gd(III) and Y(III)) clusters with slow magnetic relaxation for the dysprosium derivative.

    Science.gov (United States)

    Wang, Huiyu; Ke, Hongshan; Lin, Shuang-Yan; Guo, Yang; Zhao, Lang; Tang, Jinkui; Li, Yun-Hui

    2013-04-21

    Reactions of rare earth benzoate and nickel perchlorate with a Schiff-base ligand, 2-([(2-hydroxyphenyl)imino]methyl) phenol (H2L), in the presence of triethylamine yielded three heterobimetallic octanuclear clusters of general formula [RE3Ni5L5(PhCOO)3(μ3-OH)5(μ3-OCH3)(CH3OH)4(H2O)]·xCH3OH·yH2O (RE = Dy(III), x = 4, y = 4 (1), RE = Gd(III), x = 5, y = 4 (2), RE = Y(III), x = 5, y = 3 (3)). Single-crystal X-ray diffraction reveals that the metal core of each cluster consists of two distorted [RE2Ni2O4] cubane-like moieties and a heterobimetallic triangular [RE2NiO2] unit, with RE ions arranged in a typical triangular fashion. Variable-temperature solid state magnetic susceptibilities of these complexes were measured in the temperature range 2-300 K and the results indicate that an overall ferromagnetic interaction among the metal ions is operative for compounds 2 and 3. Under zero external field, the Dy3Ni5 compound shows a frequency dependence of the out-of-phase (χ'') signals, which indicates slow relaxation of the magnetization.

  2. Poly[(6-carboxypicolinato-κ3O2,N,O6(μ3-pyridine-2,6-dicarboxylato-κ5O2,N,O6:O2′:O6′dysprosium(III

    Directory of Open Access Journals (Sweden)

    Xu Li

    2009-11-01

    Full Text Available In the title complex, [Dy(C7H3NO4(C7H4NO4]n, one of the ligands is fully deprotonated while the second has lost only one H atom. Each DyIII ion is coordinated by six O atoms and two N atoms from two pyridine-2,6-dicarboxylate and two 6-carboxypicolinate ligands, displaying a bicapped trigonal-prismatic geometry. The average Dy—O bond distance is 2.40 Å, some 0.1Å longer than the corresponding Ho—O distance in the isotypic holmium complex. Adjacent DyIII ions are linked by the pyridine-2,6-dicarboxylate ligands, forming a layer in (100. These layers are further connected by π–π stacking interactions between neighboring pyridyl rings [centroid–centroid distance = 3.827 (3 Å] and C—H...O hydrogen-bonding interactions, assembling a three-dimensional supramolecular network. Within each layer, there are other π–π stacking interactions between neighboring pyridyl rings [centroid–centroid distance = 3.501 (2 Å] and O—H...O and C—H...O hydrogen-bonding interactions, which further stabilize the structure.

  3. 10 CFR Appendix B to Part 30 - Quantities 1 of Licensed Material Requiring Labeling

    Science.gov (United States)

    2010-01-01

    ... Cesium-135 10 Cesium-136 10 Cesium-137 10 Chlorine-36 10 Chlorine-38 10 Chromium-51 1,000 Cobalt-58m 10 Cobalt-58 10 Cobalt-60 1 Copper-64 100 Dysprosium-165 10 Dysprosium-166 100 Erbium-169 100 Erbium-171...

  4. 10 CFR 33.100 - Schedule A.

    Science.gov (United States)

    2010-01-01

    ... .1 Cesium-137 .1 .001 Chlorine-36 1 .01 Chlorine-38 100 1. Chromium-51 100 1. Cobalt-57 10 0.1 Cobalt-58m 100 1. Cobalt-58 1 .01 Cobalt-60 .1 .001 Copper-64 10 .1 Dysprosium-165 100 1. Dysprosium-166...

  5. Diffusion kinetics of boron in the X200CrMoV12 high-alloy steel

    Directory of Open Access Journals (Sweden)

    Azouani O.

    2015-01-01

    Full Text Available In this work, the kinetics of formation of the boride layers (FeB/Fe2B, formed on the X200CrMoV12 steel used for the coldworking, was investigated. The boriding treatment was carried out in the powder mixture consisting of 5%B4C, 5% NaBF4 and 90% SiC. The boriding parameters are : 900, 950 and 1000°C with treatment times of 2, 4 and 6 h. The obtained borided layers (FeB/Fe2B were characterized by the following experimental techniques: optical microscopy, scanning electron microscopy coupled to EDS analysis and XRD analysis. The kinetics of boron diffusion in the X200CrMoV12 steel was also studied. As a result, the time dependence of the borided layers thicknesses followed a growth parabolic law. The boron activation energy was estimated as 199.37 kJ mol-1 for the X200CrMoV12 steel. A full factorial design with 2 factors at 3 levels was employed to estimate the total boride layer thickness as a function of the boriding parameters (time and temperature and a simple equation was proposed. Finally, an iso-thickness diagram was given as a tool to predict the total boride layers thicknesses in relation with the practical utilization of this kind of steel.

  6. SUPERALLOYS: AN INTRODUCTION WITH THERMAL ANALYSIS ...

    African Journals Online (AJOL)

    2015-09-01

    Sep 1, 2015 ... another precipitation strengthened nickel base superalloy, has a very good strength at ... Keywords: Superalloys; Phase reactions; Differential Thermal Analysis; Latent heat of ... high-temperature strength and creep resistance. ... Borides, a relatively low density of boride particles formed when boron ...

  7. Emissivity and specific electrical resistivity of compositions in the LaB/sub 6/-ZrB/sub 2/ system

    Energy Technology Data Exchange (ETDEWEB)

    Zapadaeva, T.E.; Nikolaeva, E.E.; Ordan' yan, S.S.; Petrov, V.A.

    1987-12-01

    The authors investigate the thermionic emissivity and specific electrical resistivity of several lanthanum boride-zirconium boride systems and the dependence of these properties on the sintering regime, temperature, and structural considerations such as porosity and grain size. Emissivity was determined by calorimetry in an argon atmosphere. Results are tabulated.

  8. Methods of repairing a substrate

    Science.gov (United States)

    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.

  9. Microstructure and properties of borocarburized and laser-modified 17CrNi6-6 steel

    Science.gov (United States)

    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

  10. Characterization of complex (B + C) diffusion layers formed on chromium and nickel-based low-carbon steel

    Energy Technology Data Exchange (ETDEWEB)

    Pertek, A.; Kulka, M

    2002-12-30

    Combined surface hardening with boron and carbon was used for low-carbon chromium and nickel-based steels. The microstructure, boron contents, carbon profiles and chosen properties of borided layers produced on the carburized steels have been examined. These complex (B+C) layers are termed borburized layers. The microhardness profiles and wear resistance of these layers have been studied. In the microstructure of the borocarburized layer two zones have been observed: iron borides (FeB+Fe{sub 2}B) and a carburized layer. The depth (70-125 {mu}m) and microhardness (1500-1800 HV) of iron borides zone have been found. The carbon content (1.2-1.94 wt.%) and microhardness (700-950 HV) beneath iron borides zone have been determined. The microhardness gradient in borocarburized layer has been reduced in comparison with the only borided layer. An increase of distance from the surface is accompanied by a decrease of carbon content and microhardness in the carburized zone. The carbon and microhardness profiles of borided, carburized and borocarburized layers have been presented. A positive influence of complex layers (B+C) on the wear resistance was determined. The wear resistance of the borocarburized layer was determined to be greater in comparison with that for only borided or only carburized layers.

  11. Study on Magnetic Responsibility of Rare Earth Ferrite/Polyacrylamide Magnetic Microsphere

    Institute of Scientific and Technical Information of China (English)

    Zhang Ming; Wang Zhifeng; Zhang Hong; Dai Shaojun; Qiu Guanming; Okamoto Hiroshi

    2005-01-01

    In inverse microemulsion, rare earth ferrite/polyacrylamide magnetic microsphere were prepared and their magnetic responsibility were studied by magnetic balance. Results indicate that the magnetic responsibility of microsphere relates to magnetic moment of rare earth ion, and it can be improved by the addition of dysprosium ion of high magnetic moment. Dysprosium content has an effect on magnetic responsibility of dysprosium ferrite/polyacrylamide magnetic microsphere. The microsphere displays strong magnetic responsibility when the molar ratio of Dy3+/iron is 0.20.

  12. Poly[hexaaquatri-μ-malonato-didysprosium(III

    Directory of Open Access Journals (Sweden)

    Mei Yang

    2008-07-01

    Full Text Available The title compound, [Dy2(C3H2O43(H2O6]n, forms a coordination polymeric structure comprising hydrated dysprosium ions and malonate ligands. In the asymmetric unit, there are one dysprosium ion, one and a half malonate ligands, and three water molecules. Each DyIII atom is coordinated by six O atoms from four malonate ligands and by three water molecules, and displays a tricapped trigonal–prismatic coordination geometry. The malonate ligands adopt two types of coordination mode, linking dysprosium centres to form a three-dimensional coordination polymer. The extensive network of hydrogen bonds in this polymer enhances the structural stability.

  13. A Thermally Actuated Flux Pump for Energizing YBCO Pucks

    Science.gov (United States)

    2016-05-01

    antiferromagnetic, so heat pulses that go above and below 85 K should create a wave of magnetism across the face of the YBCO puck. The YBCO and dysprosium...temperature sensors were located at the centre and the outer perimeter on the surface of the dysprosium closest to the cold head, and on the side of the YBCO...outer perimeter of the dysprosium, the edge of the YBCO and the coldhead. In the following figures various curves are removed to give a clear picture of

  14. Maximum Permissible Concentrations and Negligible Concentrations for Rare Earth Elements (REEs)

    NARCIS (Netherlands)

    Sneller FEC; Kalf DF; Weltje L; Wezel AP van; CSR

    2000-01-01

    In dit rapport worden maximaal toelaatbare risiconiveaus (MTR) en verwaarloosbare risiconiveaus (VR) afgeleid voor zeldzame aardmetalen (ZAM). De geselecteerde ZAMs zijn Yttrium (Y), Lanthanum (La), Cerium (Ce), Praseodymium (Pr), Neodymium (Nd), Samarium (Sm), Gadolinium (Gd), en Dysprosium (Dy

  15. Atomic physics: A strange kind of liquid

    Science.gov (United States)

    Laburthe-Tolra, Bruno

    2016-11-01

    Interactions between the magnetic dipoles of dysprosium atoms in an ultracold gas can produce a 'self-bound' droplet. This provides a useful isolated system for probing the quantum-mechanical properties of ultracold gases. See Letter p.259

  16. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ Active demands from downstream industry drove the price rise of rare earth products in Chinese domestic marketrecently, particularly didymium and dysprosium products. Prices of other rare earth products remained stable.

  17. Luminescence investigation of Dy2O2S and Dy2O2SO4 obtained by thermal decomposition of sulfate hydrate

    Institute of Scientific and Technical Information of China (English)

    RV Rodrigues; L Marciniak; LU Khan; JR Matos; HF Brito; W Strk

    2016-01-01

    The yellow emitting dysprosium oxysulfide (Dy2O2S) and dysprosium oxysulfate (Dy2O2SO4) compounds were prepared from the thermal decomposition of hydrated dysprosium sulphate. The materials were characterized by using thermogravimetry (TG/DTG), X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopies. The thermal stability temperatures at around 1151 and 1313 K were determined for the Dy2O2S and Dy2O2SO4 materials, respectively. The photolumines-cence properties of the dysprosium oxysulfide were investigated, showing narrow emission bands assigned to the 4F9/2→6HJ intracon-figurational transitions of the Dy3+ion. The yellow emission color of this phosphor suggests that the Dy2O2S is a promising material for applications in LEDs.

  18. Development of Improved Burnable Poisons for Commercial Nuclear Power Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Renier, J.A.

    2002-04-17

    Burnable poisons are used in all modern nuclear reactors to permit higher loading of fuel without the necessity of an overly large control rod system. This not only permits a longer core life but can also be used to level the power distribution. Commercial nuclear reactors commonly use B{sub 4}C in separate non-fueled rods and more recently, zirconium boride coatings on the fuel pellets or gadolinium oxide mixed with the fuel. Although the advantages are great, there are problems with using these materials. Boron, which is an effective neutron absorber, transmutes to lithium and helium upon absorption of a neutron. Helium is insoluble and is eventually released to the interior of the fuel rod, where it produces an internal pressure. When sufficiently high, this pressure stress could cause separation of the cladding from the fuel, causing overly high centerline temperatures. Gadolinium has several very strongly absorbing isotopes, but not all have large cross sections and result in residual burnable poison reactivity worth at the end of the fuel life. Even if the amount of this residual absorber is small and the penalty in operation small, the cost of this penalty, even if only several days, can be very high. The objective of this investigation was to study the performance of single isotopes in order to reduce the residual negative reactivity left over at the end of the fuel cycle. Since the behavior of burnable poisons can be strongly influenced by their configuration, four forms for the absorbers were studied: homogeneously mixed with the fuel, mixed with only the outer one-third of the fuel pellet, coated on the perimeter of the fuel pellets, and alloyed with the cladding. In addition, the numbers of fuel rods containing burnable poison were chosen as 8, 16, 64, and 104. Other configurations were chosen for a few special cases. An enrichment of 4.5 wt% {sup 235}U was chosen for most cases for study in order to achieve a 4-year fuel cycle. A standard pressurized

  19. 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

    Science.gov (United States)

    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.

  20. Interfacial reactions between titanium and borate glass

    Energy Technology Data Exchange (ETDEWEB)

    Brow, R.K. [Sandia National Labs., Albuquerque, NM (United States); Saha, S.K.; Goldstein, J.I. [Lehigh Univ., Bethlehem, PA (United States). Dept. of Materials Science

    1992-12-31

    Interfacial reactions between melts of several borate glasses and titanium have been investigated by analytical scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS). A thin titanium boride interfacial layer is detected by XPS after short (30 minutes) thermal treatments. ASEM analyses after longer thermal treatments (8--120 hours) reveal boron-rich interfacial layers and boride precipitates in the Ti side of the interface.

  1. Ultra-High-Temperature-Ceramics: potentialities and barriers to the application in hot structures

    OpenAIRE

    Bellosi, Alida

    2009-01-01

    High performance Ultra-High-Temperature Composites (based on zirconium-, hafnium-, tantalum- borides and carbides) are characterized by relevant and unique thermo-physical and thermo-mechanical properties, suitable for applications in thermo-protection systems for aerospace applications. In spite of the difficult sinterability of borides and carbides of Zr, Hf, Ta, recent results highlighted that UHTC ceramics can be successfully produced with full density, fine and uniform microstructure and...

  2. Synthesis and investigation of CrB{sub 4}, MnB{sub 4} and new ternary chromium and rhenium manganese borides; Synthese und Untersuchung von CrB{sub 4}, MnB{sub 4} sowie neuen ternaeren Chrom- und Rheniummanganboriden

    Energy Technology Data Exchange (ETDEWEB)

    Knappschneider, Arno

    2014-10-13

    In the present work single crystals of the tetraborides of chromium and manganese have been grown and allowed a structure refinement of the compounds. Furthermore the physical characteristics for example hardness, electronic properties and magnetism were been determined. Also the ternary tetraboride phase of chromium and manganese was synthesized and a new ternary rhenium manganese diboride could be obtained.

  3. Syntheses, structures, and magnetic properties of a family of tetranuclear hydroxido-bridged Ni(II)2Ln(III)2 (Ln = La, Gd, Tb, and Dy) complexes: display of slow magnetic relaxation by the zinc(II)-dysprosium(III) analogue.

    Science.gov (United States)

    Abtab, Sk Md Towsif; Maity, Manoranjan; Bhattacharya, Kisholoy; Sañudo, E Carolina; Chaudhury, Muktimoy

    2012-10-01

    A new family of [2 × 2] tetranuclear 3d-4f heterometallic complexes have been synthesized. These are [Zn(2)Dy(2)L(2)(μ(3)-OH)(2)(μ(4)-OH)(dbm)(2)(MeOH)(2)](NO(3))·2H(2)O·MeOH (3), [Ni(2)Dy(2)L(2)(μ(3)-OH)(2)(μ(4)-OH)(dbm)(2)(MeOH)(2)](NO(3))·MeOH (4), [Ni(2)La(2)L(2)(μ(3)-OH)(2)(μ(4)-OH)(dbm)(2)(MeOH)(2)](ClO(4))·H(2)O·2MeOH (5), [Ni(2)Tb(2)L(2)(μ(3)-OH)(2)(μ(4)-OH)(dbm)(2) (MeOH)(2)](NO(3))·MeOH (6), and [Ni(2)Gd(2)L(2)(μ(3)-OH)(2)(μ(4)-OH)(dbm)(2)(MeOH)(2)](NO(3))·MeOH (7), [H(2)L = N,N'-dimethyl-N,N'-bis(2-hydroxy-3,5-dimethylbenzyl)ethylenediamine and Hdbm = dibenzoylmethane] obtained through a single-pot synthesis using [Zn(HL)(dbm)] (for 3)/[Ni(HL)(dbm)]·2CH(3)OH (for 4, 5, 6, and 7) as 3d-metal ion precursors. Single-crystal X-ray diffraction analysis and electrospray ionization (ESI) mass spectroscopy have been used to establish their identities. Compounds are isostructural, in which the metal ions are all connected together by a bridging hydroxido ligand in a rare μ(4)-mode. In complexes 3-7, the metal ions are antiferromagnetically coupled. Taking a cue from the results of 3 and 5, precise estimations have been made for the antiferromagnetic Ni···Ni (J(Ni) = -50 cm(-1)), Ni···Gd (J(NiGd) = -4.65 cm(-1)), and Gd···Gd (J(Gd) = -0.02 cm(-1)) exchange interactions in 7, involving the gadolinium(III) ions. The Zn(II)(2)Dy(III)(2) compound 3 has shown the tail of an out-of-phase signal in alternating current (AC) susceptibility measurement, indicative of slow relaxation of magnetization. Interestingly, the Ni(II)(2)Dy(III)(2) compound 4 in which both the participating metal ions possess large single ion anisotropy, has failed to show up any slow magnetic relaxation.

  4. 镝与二甘醇酸的配位聚合物的水热合成、晶体结构及荧光性质%Hydrothermal Synthesis, Crystal Structure and Fluorescence Property of Dysprosium Coordination Polymer with Diglycolic Acid

    Institute of Scientific and Technical Information of China (English)

    张艳斌; 鞠艳玲; 李艳秋; 李夏

    2007-01-01

    A new lanthanide coordination polymer {[Dy2(dga)3(H2O)4]·2H2O}n was prepared by hydrothermal method with DyCl3·6H2O and diglycolic acid (H2dga), and structurally characterized by single-crystal X-ray diffraction technique. The complex crystallizes in Orthorhombic system, C2221 space group with a=1.773 5(11) nm, b =0.875 2(6) nm, c=1.504 3(9) nm, V=2.335 0(3) nm3, Dc=2.359 Mg·m-3, Z=4,μ=6.447 mm-1, F(000)=1 584.0, R=0.0507, wR=0.121 6. In the complex, there are two types of coordination environments for Dy3+ ion. One Dy1 ion is nine-coordinated by three diglycolato groups via six carboxyl oxygen atoms and three ether oxygen atoms. The Dy1 ion is in a distorted monocapped square-antiprism coordination geometry. Whereas the other Dy2 ion is eight-coordinated and the coordination sphere around each Dy2 ion consists of four carboxyl oxygen atoms from four diglycolato ligands and four oxygen atoms from four coordinated water molecules. The coordination polyhedron of Dy2 ion can be described as a distorted square-antiprism. Eight- and nine-coordinate Dy3+ ions are linked by diglycolato ligands to form a 2D network structure. The fluorescence spectral of the complex in solid state at room temperature shows that the diglycolic acid is suitable for the sensitization on the luminescence of Dy3+ ion. CCDC: 660435.%DyCl3·6H2O与二甘醇酸(H2dga)在水热条件下反应得到配位聚合物{[Dy2(dga)3(H2O)4]·2H2O}n,用X-射线衍射单晶结构分析方法确定了其晶体结构.该配合物的晶体属于正交晶系,C2221空间群.在配合物中,Dy3+离子存在两种类型的配位环境.九配位的Dy1离子与3个二甘醇酸根的6个羧基氧原子和3个醚氧原子配位,其配位多面体可描述为一个扭曲的单帽四方反棱柱;八配位的Dy2离子周围的8个配位氧原子形成一个扭曲的四方反棱柱配位多面体,其中4个氧原子来自4个二甘醇酸根,另外4个氧原子由4个配位水分子提供.二甘醇酸配体的2个羧基和其醚氧原子同时与Dy3+离子配位而形成2D网状结构.该配合物在室温下的固体荧光光谱显示了中心Dy3+离子的特征荧光,位于483 nm和574 nm的发射峰分别对应于Dy3+离子的4F9/2→6H15/2和4F9/2→6H13/2跃迁.

  5. 稀土金属 Dy 掺杂 TiO2光催化剂的制备及其对孔雀石绿降解性能的研究%Study on preparation of rare earth element dysprosium doped with TiO2 photocatalyst and its degradation property to malachite green

    Institute of Scientific and Technical Information of China (English)

    高航; 高梅; 李松田; 马威; 吴晓兵

    2015-01-01

    To improve the oxidation efficiency of heterogeneous photocatalysis,TiO2 doped by rare-earth elements was adopted. The results indicate that:there was red-shift adsorption spectra of synthetic product which could enhance malachite green oxidative decolorization effectively under the action of normal visible light. Due to Dy3 + -TiO2 doped photocatalyst,activation energy of photooxidation was decreased so that the efficiency of photolysis could be improved significantly. What’s more,the treatment of malachite green model wastewater with Dy3 + -TiO2 was studied and optimal conditions has been determined as follows:the concentration of malachite green is 20 mg / L,molar ratio of Dy-doping is 1. 5% . Under that reaction con-dition,after 150 min,the decolorization rates of malachite green will be over 60% .%采用稀土元素掺杂法制备改性的二氧化钛,以改善非均相光催化的氧化效率。研究结果表明,在掺杂镝元素之后,产物的吸收光谱发生了红移,在可见光作用下,可以有效地促进孔雀石绿的氧化脱色。引入掺杂型光催化剂 Dy3+-TiO2后,可降低光氧化体系所需的能量,提高光解效率。以孔雀石绿溶液作为模拟废水,考察了 Dy3+离子掺杂量、底物浓度等因素的影响,确定了优化的实验条件:在孔雀石绿的浓度为20 mg/ L,稀土元素 Dy 掺杂量为1.5%(摩尔比)时,反应150 min 后孔雀石绿脱色率达到60%以上。

  6. N-对甲苯磺酰β-丙氨酸镝配合物的合成、晶体结构及抑菌活性%Synthesis crystal structure and antibacterial activity of dysprosium complex with N-p-tolysulfonyl-β-Alanine

    Institute of Scientific and Technical Information of China (English)

    李森兰; 马录芳; 王利亚; 黄世稳; 韦启后; 梁福沛; 张漫波

    2005-01-01

    稀土由于其特殊的电子结构,容易与一些中性、酸性和碱性生物配体形成配合物。本文合成并测定了对甲苯磺酰β-丙氨酸与稀土镝配合物的晶体结构及抑菌活性。

  7. Bis[μ-2-(4-hydroxyphenylacetato]-κ3O,O′:O;κ3O:O,O′-bis{aqua(4,4′-bipyridine-κNbis[2-(4-hydroxyphenylacetato-κ2O,O′]dysprosium(III} monohydrate

    Directory of Open Access Journals (Sweden)

    Jia-Lu Liu

    2010-12-01

    Full Text Available In the title dinuclear complex, [Dy2(C8H7O36(C10H8N22(H2O2]·H2O, the DyIII atoms are coordinated by eight O atoms from four 2-(4-hydroxyphenylacetate (HPAA ligands and a water molecule, and one N atom from a 4,4′-bipyridine (bipy ligand in a distorted tricapped trigonal prismatic geometry. Whereas four HPAA ligands coordinate to just two DyIII atoms, the remaining two ligands bridge the two DyIII atoms. In the crystal, O—H...O and O—H...N hydrogen bonds link the molecules into a three-dimensional network.

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

    Science.gov (United States)

    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

  9. AlM2B2 (M  =  Cr, Mn, Fe, Co, Ni): a group of nanolaminated materials

    Science.gov (United States)

    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.

  10. Study on wear resistant cast B-containing 1Cr18Ni9Ti stainless steel

    Institute of Scientific and Technical Information of China (English)

    Kuang Jiacai; Jiang Zhiqiang; Zhang Shiyin; Ye Chang; Liu Qicheng

    2009-01-01

    The developed 1Cr18Ni9Ti austenitic stainless steel containing 1.63 wt.%B have been characterized by X-ray diffraction (XRD), electron probe microanalyzer (EPMA), optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and Vickers microhardness measurement. The microstructural evolution and property of high boron stainless steel after solution treatment at the temperature of 1050℃ are also investigated. The results show that the main compositions of borides are Fe, Cr and B, and with small amount of Ni, Mn and C elements. Silicon is insoluble in the borides. The hardness of borides is over 1,500 HV. It has been found that borides do not decompose during solution treatment, but part of borides dissolves into the matrix. The effect of increasing the solubility of boron element in the austenitic matrix favours the hardness enhancement by 8.54%. High boron stainless steel has excellent wear resistance in corrosive environment. Lifetime of transfer pipe made of high boron-containing stainless steel is 1.5-1.8 times longer than that of boron-free 1Cr18Ni9Ti stainless steel.

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

    Science.gov (United States)

    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.

  12. Microstructure and mechanical properties of a new type of austempered boron alloyed high silicon cast steel

    Directory of Open Access Journals (Sweden)

    Chen Xiang

    2013-05-01

    Full Text Available In the present paper, a new type of austempered boron alloyed high silicon cast steel has been developed, and its microstructures and mechanical properties at different temperatures were investigated. The experimental results indicate that the boron alloyed high silicon cast steel comprises a dendritic matrix and interdendritic eutectic borides in as-cast condition. The dendritic matrix is made up of pearlite, ferrite, and the interdendritic eutectic boride is with a chemical formula of M2B (M represents Fe, Cr, Mn or Mo which is much like that of carbide in high chromium white cast iron. Pure ausferrite structure that consists of bainitic ferrite and retained austenite can be obtained in the matrix by austempering treatment to the cast steel. No carbides precipitate in the ausferrite structure and the morphology of borides remains almost unchanged after austempering treatments. Secondary boride particles precipitate during the course of austenitizing. The hardness and tensile strength of the austempered cast steel decrease with the increase of the austempering temperature, from 250 篊 to 400 篊. The impact toughness is 4-11 J昪m-2 at room temperature and the impact fracture fractogragh indicates that the fracture is caused by the brittle fracture of the borides.

  13. Poly[hexa-aqua-tri-μ-malonato-didysprosium(III)].

    Science.gov (United States)

    Fang, Zhan-Qiang; Zeng, Rong-Hua; Song, Zhao-Feng; Yang, Mei

    2008-06-07

    The title compound, [Dy(2)(C(3)H(2)O(4))(3)(H(2)O)(6)](n), forms a coordination polymeric structure comprising hydrated dysprosium ions and malonate ligands. In the asymmetric unit, there are one dysprosium ion, one and a half malonate ligands, and three water mol-ecules. Each Dy(III) atom is coordinated by six O atoms from four malonate ligands and by three water mol-ecules, and displays a tricapped trigonal-prismatic coordination geometry. The malonate ligands adopt two types of coordination mode, linking dysprosium centres to form a three-dimensional coordination polymer. The extensive network of hydrogen bonds in this polymer enhances the structural stability.

  14. Poly[hexa­aqua­tri-μ-malonato-didysprosium(III)

    Science.gov (United States)

    Fang, Zhan-Qiang; Zeng, Rong-Hua; Song, Zhao-Feng; Yang, Mei

    2008-01-01

    The title compound, [Dy2(C3H2O4)3(H2O)6]n, forms a coordination polymeric structure comprising hydrated dysprosium ions and malonate ligands. In the asymmetric unit, there are one dysprosium ion, one and a half malonate ligands, and three water mol­ecules. Each DyIII atom is coordinated by six O atoms from four malonate ligands and by three water mol­ecules, and displays a tricapped trigonal–prismatic coordination geometry. The malonate ligands adopt two types of coordination mode, linking dysprosium centres to form a three-dimensional coordination polymer. The extensive network of hydrogen bonds in this polymer enhances the structural stability. PMID:21202748

  15. Effect of boron addition on the microstructure and stress-rupture properties of directionally solidified superalloys

    Institute of Scientific and Technical Information of China (English)

    Bao-ping Wu; Lin-han Li; Jian-tao Wu; Zhen Wang; Yan-bin Wang; Xing-fu Chen; Jian-xin Dong; Jun-tao Li

    2014-01-01

    This study is focused on the effect of boron addition, in the range of 0.0007wt% to 0.03wt%, on the microstructure and stress-rupture properties of a directionally solidified superalloy. With increasing boron content in the as-cast alloys, there is an increase in the fraction of theγ′/γ eutectic and block borides precipitate around theγ′/γ eutectic. At a high boron content of 0.03wt%, there is precipitation of lamellar borides. Upon heat treatment, fine block borides tend to precipitate at grain boundaries with increasing boron content. Overall, the rupture life of the directionally solidified superalloy is significantly improved with the addition of nominal content of boron. However, the rupture life decreases when the boron content exceeds 0.03wt%.

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

    Energy Technology Data Exchange (ETDEWEB)

    Krivezhenko, Dina S., E-mail: dinylkaa@yandex.ru; Drobyaz, Ekaterina A., E-mail: ekaterina.drobyaz@yandex.ru; Bataev, Ivan A., E-mail: ivanbataev@ngs.ru; Chuchkova, Lyubov V., E-mail: twitty-kun@mail.ru [Novosibirsk State Technical University, Novosibirsk, 630073 (Russian Federation)

    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.

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

    Science.gov (United States)

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

    2015-10-01

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

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

    Science.gov (United States)

    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.

  19. Synthesis and Characterization of TiB2 Reinforced Aluminium Matrix Composites: A Review

    Science.gov (United States)

    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.

  20. Poly[hexa­aqua­tri-μ-malonato-didysprosium(III)

    OpenAIRE

    2008-01-01

    The title compound, [Dy2(C3H2O4)3(H2O)6]n, forms a coordination polymeric structure comprising hydrated dysprosium ions and malonate ligands. In the asymmetric unit, there are one dysprosium ion, one and a half malonate ligands, and three water molecules. Each DyIII atom is coordinated by six O atoms from four malonate ligands and by three water molecules, and displays a tricapped trigonal–prismatic coordination geometry. The malonate ligands adopt two types of coordination mode, linkin...

  1. Photoluminescence, trap states and thermoluminescence decay process study of Ca2MgSi2O7 : Eu2+, Dy3+ phosphor

    Indian Academy of Sciences (India)

    Ravi Shrivastava; Jagjeet Kaur; Vikas Dubey; Beena Jaykumar

    2014-06-01

    Europium and dysprosium-doped calcium magnesium silicate powder with different concentrations of dysprosium were synthesized using solid-state reaction. The Fourier transform infrared (FT–IR) spectra confirmed the proper preparation of the sample. The prepared phosphors were characterized using photoluminescence excitation and emission spectra. Prominent green colour emission was obtained under ultraviolet excitation. The thermoluminescence glow curves of the samples were measured at various delay times. With increased delay time, the intensity of the thermoluminescence peak decays and the position of the thermoluminescence peak shifts towards higher temperature, indicating the considerable retrapping associated with general order kinetics.

  2. Superhard W0.5Ta0.5B nanowires prepared at ambient pressure

    Science.gov (United States)

    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.

  3. Protective metal matrix coating with nanocomponents

    Science.gov (United States)

    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.

  4. New Process for Grain Refinement of Aluminum. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    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.

  5. Perovskite catalysts for oxidative coupling

    Science.gov (United States)

    Campbell, Kenneth D.

    1991-01-01

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

  6. Rare Earths; The Fraternal Fifteen (Rev.)

    Energy Technology Data Exchange (ETDEWEB)

    Gschneidner, Jr., Karl A. [Iowa State University; Ames Laboratory

    1966-01-01

    Rare earths are a set of 15 elements: lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium. They are not rare and not earths; they are metals and quite abundant. They are studied to develop commercial products which are beneficial to mankind, and because some rare earths are important to fission products.

  7. An organometallic sandwich lanthanide single-ion magnet with an unusual multiple relaxation mechanism.

    Science.gov (United States)

    Jeletic, Matthew; Lin, Po-Heng; Le Roy, Jennifer J; Korobkov, Ilia; Gorelsky, Serge I; Murugesu, Muralee

    2011-12-07

    A dysprosium(III) sandwich complex, [Dy(III)(COT″)(2)Li(THF)(DME)], was synthesized using 1,4-bis(trimethylsilyl)cyclooctatetraenyl dianion (COT″). The complex behaves as a single-ion magnet and demonstrates unusual multiple relaxation modes. The observed relaxation pathways strongly depend on the applied static dc fields.

  8. On the use of Liouville relaxation supermatrices in Mössbauer studies. III : Application to Mössbauer relaxation in superconductors

    OpenAIRE

    Hartmann-Boutron, F.

    1980-01-01

    Wagner et al. recently studied the Mössbauer relaxation of paramagnetic dysprosium as an impurity in superconducting thorium. In connection with this study, we have derived simple formulas for interpreting relaxation effects in 2+ 0+ Mössbauer transitions of rare earth ions in superconductors.

  9. High-pressure synthesis of {nu}-DyBO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Emme, H.; Huppertz, H. [Dept. Chemie und Biochemie, Ludwig-Maximilians-Univ. Muenchen, Muenchen (Germany)

    2004-12-01

    {nu}-Dysprosium borate ({nu}-DyBO{sub 3}) was synthesized under conditions of high temperature and pressure in a Walker-type multi-anvil apparatus at 3 GPa and 1323 K. The compound is isotypic with the already known {nu}-samarium and {nu}-europium orthoborates. (orig.)

  10. Note: Simple means for selective removal of the 365 nm line from the Hg spectrum using Dy

    DEFF Research Database (Denmark)

    Vesborg, Peter Christian Kjærgaard; Chorkendorff, Ib; Brock-Nannestad, T.

    2011-01-01

    The emission spectrum of mercury has a notable line at about 365 nm under both low and medium-high pressure conditions. A simple filter based on a solution of dysprosium ions, Dy3+, is shown to be very useful for applications of Hg-light sources where this line is unwanted. The presented filter i...

  11. Benzoxazole-based heterometallic dodecanuclear complex [Dy(III)4Cu(II)8] with single-molecule-magnet behavior.

    Science.gov (United States)

    Iasco, Olga; Novitchi, Ghenadie; Jeanneau, Erwann; Wernsdorfer, Wolfgang; Luneau, Dominique

    2011-08-15

    Three Cu-Ln (Ln = Dy, Gd, Y) dodecanuclear clusters assembled by a novel ligand of the benzoxazole type are reported. The dysprosium cluster exhibits a frequency dependence of the alternating-current susceptibility and hysteresis loop at low temperature, indicating single-molecule-magnet behavior.

  12. Market Review

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ RE Market Dec. 10-20 Price of Pr-Nd oxide and Pr-Nd mischrnetal kept on rising in domestic market recently due to the tight supply of RE carbonate. Short supply of ion adsorption clay in southern China did not affect the prices of dysprosium and terbium obviously.

  13. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    June 20-30, 2011 Prices of heavy rare earth products remained soaring. The same happened to dysprosium and its related products due to tight supply. Separation plants held tightly of europium oxide. Refining plants took a positive attitude toward the ma

  14. Market Review

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Rare earth market was inactive affected by sluggish demand for didymium mischmetal and dysprosium metal by NdFeB industry. Most enterprises were waiting to see what was going on with the industry. However, price of didymium oxide rose again and price of heavy rare earths kept strong. Price of Dy oxide and Yt oxide Kept on rising.

  15. Market Review

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ RE Market May 10-20 Learned from Inner Mongolia Rare Earth Association,domestic rare earth market was in good situation driven by high demand. Price of neodymium rose strongly. Dysprosium oxide and terbium oxide still hovered at the higher price level. Price of europia remained stable.

  16. Market Review RE Market April 20-30

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ Driven by high demand, China rare earth market was in good situation. Dysprosium oxide and terbium oxide hovered at the higher price level. Price of Pr-Nd oxide kept upward.Price of SmEuGd rose on small extent.

  17. Infrared Transparent Selenide Glasses.

    Science.gov (United States)

    1997-03-14

    crystalline halides, silica and fluoride glasses, and chalcogenide glasses. Crystalline halides undergo plastic deformation and are hygroscopic...mainly for applications operating at wavelengths less than 3 microns. Silicate and fluoride glasses have been developed as optical fiber amplifiers...activity. Preferred rare earths includes praseodymium, neodymium, erbium, cerium , dysprosium, holmium, thulium, terbium, ytterbium or mixtures of

  18. Synthesis and structure of didysprosium complexes with a tetraketone

    Science.gov (United States)

    Yang, Luqin; Yang, Rudong

    1996-06-01

    Two novel didysprosium (Dy 2) complexes of 1,5-bis(1'-phenyl-3'-methyl-5'-pyrazolone-4')-1,5-pentanedione (H 2L), Dy 2L 3·2H 2O and Dy 2L 3·5DMF (DMF = dimethylformamide), have been synthesized. The crystal structure of Dy 2L 3·5DMF was determined by X-ray diffraction. Crystals are triclinic, space group P1¯, with a = 16.99(1), b = 17.970(9), c = 18.28(1) Å, α = 110.36(4), β = 101.47(6), γ = 111.11(5)°, V = 4533(9) Å 3, Mr = 2017.91, Z = 2, D x = 1.48 g cm -3, μ = 17.22 cm -1, F(000) = 2056, R = 0.074 with 3804 reflections used in the refinement. In the complex, each L bonds two dysprosium atoms with its two β-diketone groups. Two DMF solvent molecules bond to each dysprosium ion. The coordination number of the two dysprosium ions is eight. The eight oxygen atoms around the dysprosium ion make up a distorted square antiprism coordination polyhedron. The resonance structures of coordinated β-diketonates are also discussed. Different lanthanide ions may stabilize the specific structure.

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

    Science.gov (United States)

    Imashuku, Susumu; Wagatsuma, Kazuaki; Kawai, Jun

    2016-02-01

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

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

    Science.gov (United States)

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

    2014-10-21

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

  1. Evidence for triaxial deformation near N=86 : Collective bands in Dy-152,Dy-153 and Ho-153

    NARCIS (Netherlands)

    Appelbe, DE; Twin, PJ; Beausang, CW; Cullen, DM; Curien, D; Duchene, G; Erturk, S; Finck, C; Haas, B; Paul, ES; Radford, DC; Rigollet, C; Smith, MB; Stezowski, O; Waddington, JC; Wilson, AN

    2002-01-01

    The N=86,87 isotopes of dysprosium and holmium have been investigated using the Eurogam II gamma-ray spectrometer. A new collective rotational band has been observed in Ho-153 and the previously observed nui(13/2) band in Dy-153 has been extended to much higher spin. Comparing these bands and

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

    Science.gov (United States)

    2016-04-01

    specific ana - tomic features or dynamic processes. The most widely used MRI contrast agents consist of various chelated forms of Gd3þ where the...Vymazal J, Holla M, Frank JA. Dysprosium-DOTA-PAMAM dendrimers as macromolecu- lar T2 contrast agents - preparation and relaxometry. Invest Radiol

  3. Preparation, Structure Characterization and Thermal Decomposition ...

    African Journals Online (AJOL)

    NJD

    The unit cell contains a dinuclear molecule of the title compound. ... The carboxylate groups are bonded to the dysprosium ions in two modes: chelating bidentate ..... 5 R.F. Wang, L.S. Li, L.P. Jin and S.Z. Lu,J. Rare Earths,1998,16, 149–152.

  4. Market Review

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Rare earth market went downward recently.Consumers worried about the continuous price falling in the following one month and were not active in the purchasing.Price of southern ion adsorption clay dropped as well,which consequently resulted in the falling of dysprosium and terbium.

  5. Quantitative assessment of mono- and polysulphide-linked carbon skeletons of S-rich macromolecular aggregates present in bitumens and oils

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Schouten, S.; Baas, M.; Kock-van Dalen, A.C.; Kohnen, M.E.L.; Leeuw, J.W. de

    1995-01-01

    Polar fractions of three immature sulphur-rich sediments and four sulphur-rich oils, all of Miocene age, were studied using two selective chemolytic methods, namely methyl lithium/methyl iodide, which selectively cleaves polysulphide bonds, and Raney nickel or nickel boride which cleave both mono-an

  6. Laser surface alloying of commercially pure titanium with boron and carbon

    Science.gov (United States)

    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.

  7. Mechanical properties of titanium alloys with strengthened surface layers

    Directory of Open Access Journals (Sweden)

    I.M. Pohreliuk

    2011-12-01

    Full Text Available Influence of oxinitriding and boriding on the mechanical properties (ultimate strength to destruction at uniaxial tension, plasticity, tendency to delayed destruction, fatigue resistance at bending with rotation, fatigue life at lowcycle pure bending of titanium alloys is studied.

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

    Science.gov (United States)

    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.

  9. Microstructure of Ti6Al4V reinforced by coating W particles through laser metal deposition

    CSIR Research Space (South Africa)

    Ndou, N

    2016-10-01

    Full Text Available -0958 (Print); ISSN: 2078-0966 (Online) WCECS 2016 [5] S. A. Tsipas, M. Vázquez-alcázar, E. M. R. Navas, & E. Gordo, Boride coatings obtained by pack cementation deposited on powder metallurgy and wrought Ti and Ti–6Al–4V. Surface and Coatings Technology...

  10. PRODUCTION OF GRADIENT MATERIALS BY MEANS OF SVS IN THE FIELD OF MASS POWERS

    Directory of Open Access Journals (Sweden)

    V. V. Klubovich

    2011-01-01

    Full Text Available Influence of centrifugal overload on distribution of refractory strengthening particles in volume of melt is studied, structures of initial burden and methods of centrifugal casting of samples from materials on the basis of iron with high wear resistance and gradient distribution of particles of carbides and borides are developed.

  11. Review on Superconducting Materials

    OpenAIRE

    Hott, Roland; Kleiner, Reinhold; Wolf, Thomas; Zwicknagl, Gertrud

    2013-01-01

    Short review of the topical comprehension of the superconductor materials classes Cuprate High-Temperature Superconductors, other oxide superconductors, Iron-based Superconductors, Heavy-Fermion Superconductors, Nitride Superconductors, Organic and other Carbon-based Superconductors and Boride and Borocarbide Superconductors, featuring their present theoretical understanding and their aspects with respect to technical applications.

  12. Molecular indicators for palaeoenvironmental change in a Messinian evaporitic sequence (Vena del Gesso, Italy) II. Stratigraphic changes in abundances and (13)C contents of free and sulphur-bound skeletons in a single marl bed

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Kenig, F.; Frewin, N.L.; Hayes, J.M.

    1995-01-01

    The extractable organic matter of 10 immature samples from a marl bed of one evaporitic cycle of the Vena del Gesso sediments (Gessoso-solfifera Fm., Messinian, Italy) was analyzed quantitatively for free hydrocarbons and organic sulphur compounds. Nickel boride was used as a desulphurizing agent to

  13. High-temperature materials program. Progress report No. 34, Part B

    Energy Technology Data Exchange (ETDEWEB)

    1964-04-15

    Information is presented concerning coated fuel particle development and evaluation; burnup capabilities of Y/sub 2/O/sub 3/-stabilized UO/sub 2/ and stabilized fuel - BeO matrix materials; high-temperature studies of substoichiometric urania and urania solid solutions; high-temperature carbides and borides research; and high-flux reactor materials gaseous fuels research.

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

    Science.gov (United States)

    2015-05-26

    1930). [15] R. Kiessling and Y. H. Liu, Thermal stability of the chromium, iron, and tungsten borides in streaming ammonia and the existence of a new...Prediction of novel phases of tantalum(V) nitride and tungsten(VI) nitride that can be synthesized under high pressure and high temperature, Angew. Chem

  15. Ultra high temperature ceramics (UHTCs) for severe environment

    OpenAIRE

    Sciti, Diletta; Bellosi, Alida; Guicciardi, Stefano; Monteverde, Frederic; Medri, Valentina; Silvestroni, Laura

    2010-01-01

    Borides and carbides of Hf, Ta, Zr and related composites are materials of great interest. These groups of ceramics, combining outstanding levels of robustness and refractoriness, are currently widely recognized as the unique materials for harsh service environnients, especially for aerospace, rocket propulsion and energy applications

  16. Quantitative assessment of mono- and polysulphide-linked carbon skeletons of S-rich macromolecular aggregates present in bitumens and oils

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Schouten, S.; Baas, M.; Kock-van Dalen, A.C.; Kohnen, M.E.L.; Leeuw, J.W. de

    1995-01-01

    Polar fractions of three immature sulphur-rich sediments and four sulphur-rich oils, all of Miocene age, were studied using two selective chemolytic methods, namely methyl lithium/methyl iodide, which selectively cleaves polysulphide bonds, and Raney nickel or nickel boride which cleave both mono-an

  17. Laser Boronizing of Stainless Steel with Direct Diode Laser

    Science.gov (United States)

    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.

  18. The adhesion of hot-filament CVD diamond films on AISI type 316 austenitic stainless steel

    NARCIS (Netherlands)

    Buijnsters, J.G.; Shankar, P.; Enckevort, W.J.P. van; Schermer, J.J.; Meulen, J.J. ter

    2004-01-01

    Steel ball indentation and scratch adhesion testing of hot filament chemical vapour deposited diamond films onto AISI type 316 austenitic stainless steel substrates using two different interlayer systems, namely chromium nitride and borided steel, have been investigated. In order to compare the adhe

  19. Laser alloying of bearing steel with boron and self-lubricating addition

    Directory of Open Access Journals (Sweden)

    Kotkowiak Mateusz

    2016-12-01

    Full Text Available 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.

  20. Joint electroreduction of lanthanum, gadolinium and boron in halide melts

    Directory of Open Access Journals (Sweden)

    Khushkhov KH.B.

    2003-01-01

    Full Text Available The joint electroreduction of La, Gd and B from chloride-fluoride melts has been studied by cyclic voltametry. Based on the analysis of voltamograms the possibility of electrosynthesis of lanthanum-gadolinium borides from chloride-fluoride melts has been shown.

  1. Strengthening of Metals by Means of Fibers. Chapter 6 and 7,

    Science.gov (United States)

    1979-04-03

    oxides (ZrU2 , Hf02, Th02 ), borides, nitrides and car- bides of hafnium and tantalum carbide. Then the oxides and chemical compounds were pulled along...verstirkem Aluminium . Tagung Verbundwerkstoffe, Konstanz, BRD, 22-23.X 1970. 24. B. H. Koemuxoe, B. B. Kviunoe, B. B. Cxypaun, JO. A. )Jlecmepun. nas

  2. Boron Carbides As Thermo-electric Materials

    Science.gov (United States)

    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.

  3. Toughening mechanism for Ni-Cr-B-Si-C laser deposited coatings

    NARCIS (Netherlands)

    Hemmati, I.; Ocelik, V.; De Hosson, J. Th. M.

    2013-01-01

    Laser deposited coatings were made from Colmonoy 69 Ni-Cr-B-Si-C alloy and Nb-modified Colmonoy 69 using laser cladding with powder injection. Addition of Nb was done to decrease the structural scale of Cr boride precipitates by providing Nb-rich nucleation agents. The purpose of the study was to ev

  4. Laser cladding of aluminium using TiB2

    CSIR Research Space (South Africa)

    Kumar, S

    2010-03-01

    Full Text Available - erties of the boride layers laser fabricated on Ti-6Al-4V al- loy. Journal of Materials Pro- cessing Technology, 209, 2887- 2891. [7] Abboud, J. H. and West, D. R. F. (1994) Microstructure of Ti-TiB2 surface layers pro- duced by laser particle...

  5. Flydende fase sintring af rustfrit stål

    DEFF Research Database (Denmark)

    Maahn, Ernst Emanuel; Mathiesen, Troels

    1998-01-01

    on addition of boride to AISI 316L type steels has previously proved to be sensitive to intergranular corrosion due to formation of intermetallic phases. In order to improve this system further, application of other alloy systems based on a higher alloyed 904L type stainless steel powder (PM 150) has been...

  6. Low-Pressure Self-Propagating High-Temperature Synthesis.

    Science.gov (United States)

    titanium carbide and titanium boride from the elements without applying isostatic pressure. The experimental study was limited to the synthesis of... titanium carbide and titanium bioride with and without a nickel matrix phase. SHS is now state of the art in the Soviet Union for the production of

  7. Characterization of natural zeolite clinoptilolite for sorption of contaminants

    Energy Technology Data Exchange (ETDEWEB)

    Xingu-Contreras, E., E-mail: nyleve-18@hotmail.com; García-Rosales, G., E-mail: gegaromx@yahoo.com.mx [Instituto Tecnológico de Toluca (Mexico); García-Sosa, I., E-mail: irma.garcia@inin.gob.mx; Cabral-Prieto, A., E-mail: agustin.cabral@inin.gob.mx; Solache-Ríos, M., E-mail: marcos.solache@inin.gob.mx [Instituto Nacional de Investigaciones Nucleares, Departamento de Química (Mexico)

    2015-06-15

    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{sup ∘} (2θ), inferring the presence of nanocrystals of Fe{sub 2}B as identified from Mössbauer Spectroscopy. The size of these Fe{sub 2}B 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 %.

  8. Characterization of natural zeolite clinoptilolite for sorption of contaminants

    Science.gov (United States)

    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 %.

  9. Effect of Relative Humidity on the Tribological Properties of Self-Lubricating H3BO3 Films Formed on the Surface of Steel Suitable for Biomedical Applications

    Directory of Open Access Journals (Sweden)

    E. Hernández-Sanchez

    2015-01-01

    Full Text Available The effect of environmental humidity on the self-lubricating properties of a thin film of boric acid (H3BO3 was evaluated. H3BO4 films were successfully formed on the surface of AISI 316L steel. The study was conducted on AISI 316L steel because of its use in biomedical applications. First, the samples were exposed to boriding to generate a continuous surface layer of iron borides. The samples were then exposed to a short annealing process (SAP at 1023 K for 5 min and cooled to room temperature while controlling the relative humidity (RH. Five different RH conditions were tested. The purpose of SAP was to promote the formation of a surface film of boric acid from the boron atoms present in the iron boride layers. The presence of the boric acid at the surface of the borided layer was confirmed by Raman spectroscopy and X-ray diffraction (XRD. The self-lubricating capability of the films was demonstrated using the pin-on-disk technique. The influence of RH was reflected by the friction coefficient (FC, as the samples cooled with 20% of RH exhibited FC values of 0.16, whereas the samples cooled at 60% RH showed FC values of 0.02.

  10. Analysis of boron carbides' electronic structure

    Science.gov (United States)

    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.

  11. Photovoltaic cell

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  13. Anomalies in thermal expansion and heat capacity of TmB50 at low temperatures: magnetic phase transition and crystal electric field effect.

    Science.gov (United States)

    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.

  14. Enhanced boronizing kinetics of alloy steel assisted by surface mechanical attrition treatment

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Haopeng, E-mail: hpyang1993@163.com; Wu, Xiaochun, E-mail: xcwu@staff.shu.edu.cn; Yang, Zhe; Pu, Shengjun; Wang, Hongbin

    2014-03-25

    Highlights: • Nanostructured surface layer is fabricated on H13 steel assisted by SMAT. • The boronizing kinetics of SMAT sample can be enhanced remarkably. • Borided layer can delay fatigue cracks initiation and impede their propagation. -- Abstract: A nanostructured surface layer was fabricated on AISI H13 steel by means of surface mechanical attrition treatment (SMAT). Boronizing behaviors of the SMAT samples were systematically investigated in comparison with their coarse-grained counterparts. The boron diffusion depth of the SMAT sample with pack boriding treatment at 600 °C for 2 h was about 8 μm, which was much deeper than that of the coarse-grained sample. A much thicker borided layer on the SMAT sample can be synthesized by a duplex boronizing treatment at 600 °C followed by at a higher temperature. The borided layer was composed with monophase of Fe{sub 2}B and the growth of it exhibited a (0 0 2) preferred orientation. Moreover, the activation energy of boron diffusion for the SMAT sample is 140.3 kJ/mol, which is much lower than 209.4 kJ/mol for the coarse-grained counterpart. The results indicate that the boronizing kinetics can be significantly enhanced in the SMAT sample with a duplex boronizing treatment. Furthermore, the thermal fatigue tests show that the borided layer with excellent oxidation resistance and mechanical strength at elevated temperatures could effectively delay the thermal fatigue cracks initiation and impede their propagation. Therefore, the thermal fatigue property of H13 steel with a duplex boronizing treatment can be improved remarkably.

  15. Material Flow Analysis of NdFeB magnets for Denmark: A comprehensive waste flow sampling and analysis approach

    DEFF Research Database (Denmark)

    Habib, Komal; Schibye, Peter Klausen; Vestbø, Andreas Peter

    2014-01-01

    Neodymium-iron-boron (NdFeB) magnets have become highly desirable for modern hi-tech applications. These magnets, in general, contain two key Rare Earth Elements (REEs) i.e. neodymium (Nd) and dysprosium (Dy), which are responsible for the very high strength of these magnets allowing for consider......Neodymium-iron-boron (NdFeB) magnets have become highly desirable for modern hi-tech applications. These magnets, in general, contain two key Rare Earth Elements (REEs) i.e. neodymium (Nd) and dysprosium (Dy), which are responsible for the very high strength of these magnets allowing...... of stocks and flows of NdFeB magnets in Denmark. A novel element of this study is the value added to the traditionally practiced MFAs at national and/or global level by complementing them with a comprehensive sampling and elemental analysis of NdFeB magnets, taken out from a sample of 157 different products...

  16. Magnetic Properties of the Dy1-xUxCo3 System

    Science.gov (United States)

    Lupşa, Ileana; Petrişor, T.; Balasz-Mureşan, I.

    The magnetic properties of Dy1-xUxCo3 system were investigated in the 4.3-1150 K temperature range and magnetic field up to 120 kOe. The crystalline structure is rhombohedral of PuNi3 type. For x≤0.8, the samples exhibit a ferrimagnetic behavior. The uranium substitution for dysprosium leads to the decreasing of the exchange field and the reducing of the magnetization and the transition temperatures. The Co mean moments (1.9μB/Co for x=0) opposite to the dysprosium ones and the mean effective Co moments (3.75μB/Co for x=0) are gradually decreasing as Dy is replaced by uranium.

  17. Tetraanionic biphenyl lanthanide complexes as single-molecule magnets.

    Science.gov (United States)

    Huang, Wenliang; Le Roy, Jennifer J; Khan, Saeed I; Ungur, Liviu; Murugesu, Muralee; Diaconescu, Paula L

    2015-03-02

    Inverse sandwich biphenyl complexes [(NN(TBS))Ln]2(μ-biphenyl)[K(solvent)]2 [NN(TBS) = 1,1'-fc(NSi(t)BuMe2)2; Ln = Gd, Dy, Er; solvent = Et2O, toluene; 18-crown-6], containing a quadruply reduced biphenyl ligand, were synthesized and their magnetic properties measured. One of the dysprosium biphenyl complexes was found to exhibit antiferromagnetic coupling and single-molecule-magnet behavior with Ueff of 34 K under zero applied field. The solvent coordinated to potassium affected drastically the nature of the magnetic interaction, with the other dysprosium complex showing ferromagnetic coupling. Ab initio calculations were performed to understand the nature of magnetic coupling between the two lanthanide ions bridged by the anionic arene ligand and the origin of single-molecule-magnet behavior.

  18. Spectroscopy of Neutron-Rich $^{168,170}$Dy: Yrast Band Evolution Close to the $N_{p}N_{n}$ Valence Maximum

    CERN Document Server

    Söderström, P A; Regan, P H; Algora, A; de Angelis, G; Ashley, S F; Aydin, S; Bazzacco, D; Casperson, R J; Catford, W N; Cederkäll, J; Chapman, R; Corradi, L; Fahlander, C; Farnea, E; Fioretto, E; Freeman, S J; Gadea, A; Gelletly, W; Gottardo, A; Grodner, E; He, C Y; Jones, G A; Keyes, K; Labiche, M; Liang, X; Liu, Z; Lunardi, S; Muarginean, N; Mason, P; Menegazzo, R; Mengoni, D; Montagnoli, G; Napoli, D; Ollier, J; Pietri, S; Podolyák, Z; Pollarolo, G; Recchia, F; Şahin, E; Scarlassara, F; Silvestri, R; Smith, J F; Spohr, K M; Steer, S J; Stefanini, A M; Szilner, S; Thompson, N J; Tveten, G M; Ur, C A; Valiente-Dobón, J J; Werner, V; Williams, S J; Xu, F R; Zhu, J Y

    2010-01-01

    The yrast sequence of the neutron-rich dysprosium isotope Dy-168 has been studied using multi-nucleon transfer reactions following the collision of a 460-MeV Se-82 beam and a Er-170 target. The reaction products were identified using the PRISMA magnetic spectrometer and the gamma rays detected using the CLARA HPGe-detector array. The 2+ and 4+ members of the previously measured ground state rotational band of Dy-168 was confirmed and the yrast band extended up to 10+. A tentative candidate for the 4+ to 2+ transition in Dy-170 was also identified. The data on this and lighter even-even dysprosium isotopes are interpreted in terms of Total Routhian Surface calculations and the evolution of collectivity approaching the proton-neutron valence product maximum is discussed.

  19. Development of a coprecipitation system for the speciation/preconcentration of chromium in tap waters

    Energy Technology Data Exchange (ETDEWEB)

    Karatepe, Aslihan, E-mail: karatepea@gmail.com [Nevsehir University, Faculty of Science and Arts, Department of Chemistry, 50000 Nevsehir (Turkey); Korkmaz, Esra [Bozok University, Faculty of Science and Arts, Department of Chemistry, Yozgat (Turkey); Soylak, Mustafa [Erciyes University, Faculty of Science and Arts, Chemistry Department, 38039 Kayseri (Turkey); Elci, Latif [Pamukkale University, Faculty of Science and Arts, Department of Chemistry, 20020 Denizli (Turkey)

    2010-01-15

    A method for the speciation of chromium(III), chromium(VI) and determination of total chromium based on coprecipitation of chromium(III) with dysprosium hydroxide has been investigated and applied to tap water samples. Chromium(III) was quantitatively recovered by the presented method, while the recovery values for chromium(VI) was below 10%. The influences of analytical parameters including amount of dysprosium(III), pH, centrifugation speed and sample volume for the quantitative precipitation were examined. No interferic effects were observed from alkali, earth alkali and some transition metals for the analyte ions. The detection limits (k = 3, N = 15) were 0.65 {mu}g/L for chromium(III) and 0.78 {mu}g/L for chromium(VI). The validation of the presented method was checked by the analysis of certified reference materials.

  20. Development of bulk metallic glasses based on the Dy-Al binary eutectic composition

    Institute of Scientific and Technical Information of China (English)

    LUO Lin; TIAN Rui; XIAO Xueshan

    2008-01-01

    A series of dysprosium-based ternary, quadruple, and quintuple bulk metallic glasses (BMGs) based on Dy-Al binary eutectic compo-sition were obtained with the partial substitution of Co, Gd, and Ni elements, for dysprosium. The results showed that the Dy31Gd25Co20Al24 alloy, which had the best glass forming ability (GFA), could be cast into an amorphous rod with a diameter of 5 mm. The GFA of alloys was evaluated on the basis of the supercooled liquid region width, γ parameter, the formation enthalpy, and the equivalent electronegativity difference of amor-phous alloys. It was found that the eutectic composition was closely correlated with the GFA of the Dy-based BMGs.

  1. Dysprosium carbide iodides Dy{sub 10}(C{sub 2}){sub 2}I{sub 18}, Dy{sub 4}(C{sub 2})I{sub 6} and Dy{sub 12}(C{sub 2}){sub 3}I{sub 17}; Dysprosiumcarbidiodide Dy{sub 10}(C{sub 2}){sub 2}I{sub 18}, Dy{sub 4}(C{sub 2})I{sub 6} und Dy{sub 12}(C{sub 2}){sub 3}I{sub 17}

    Energy Technology Data Exchange (ETDEWEB)

    Mattausch, H.; Hoch, C.; Simon, A. [Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany)

    2007-02-15

    The title compounds are formed by reaction of DyI{sub 3}, Dy metal and C in stoichiometric amounts in closed Ta ampoules, Dy{sub 10}(C{sub 2}){sub 2}I{sub 18} at 930 C for 7 days, Dy{sub 4}(C{sub 2})I{sub 6} at 950 C for 6 days and Dy{sub 12}(C{sub 2}){sub 3}I{sub 17} at 900 C for 11 days as pure samples according to X-ray powder diffraction. Dy{sub 10}(C{sub 2}){sub 2}I{sub 18} crystallizes in space group P2{sub 1}/c with a = 10.470(2), b = 17.152(3), c = 13.983(3) Aa and {beta} = 121.14(3) , Dy{sub 4}(C{sub 2})I{sub 6} in Pnnm with a = 13.622(3), b = 14.335(3) and c = 8.396(2) Aa, and Dy{sub 12}(C{sub 2}){sub 3}I{sub 17} in C2/c with a = 19.149(4), b = 12.069(2), c = 18.595(4) Aa, and {beta} = 90.54(3) . The crystal structure of Dy{sub 10}(C{sub 2}){sub 2}I{sub 18} is composed of Dy double octahedra centered by (C{sub 2}){sup 6-} groups (ethanide) with the iodide ions above the edges and the corners of the Dy{sub 10}(C{sub 2}){sub 2} units. In Dy{sub 4}(C{sub 2})I{sub 6} the Dy atoms form chains of trans-edge sharing octahedra with embedded (C{sub 2}) groups. In the structure of Dy{sub 12}(C{sub 2}){sub 3}I{sub 17} alternately cis-, trans-edge-condensed Dy{sub 6} octahedra centered by (C{sub 2}) groups occur. The iodine atoms surround the chains like in the M{sub 6}X{sub 12} cluster and interconnect neighboring chains. (orig.)

  2. Concepts for using trapped-flux bulk high-temperature superconductor in motors and generators

    Science.gov (United States)

    Hull, John R.; Strasik, Michael

    2010-12-01

    We review previous concepts for using bulk high-temperature superconductors (HTSs) in motors and generators and discuss methods for using trapped-flux (TF) HTSs in motors and generators that have been recently investigated in our laboratory. We examine the expected performance of a brushless motor/generator that uses TF bulk HTSs to provide magnetomotive force, where the stator windings are used to create the TF. A key feature is the use of dysprosium for the stator and rotor cores.

  3. Concepts for using trapped-flux HTS in motors and generators

    Science.gov (United States)

    Hull, John R.; Strasik, Michael

    2013-01-01

    We examine the expected performance of a brushless motor/generator that uses trapped-flux (TF) bulk high-temperature superconductors (HTSs) to provide magnetomotive force, where the stator windings are used to create the TF. A key feature is the use of dysprosium (Dy) for the stator and rotor cores. We also examine methods to energize TF in HTS for generators used in pulsed-power applications.

  4. Concepts for using trapped-flux bulk high-temperature superconductor in motors and generators

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R; Strasik, Michael [Boeing Research and Technology, PO Box 3707, MC 2T-50, Seattle, WA 98124-2207 (United States)

    2010-12-15

    We review previous concepts for using bulk high-temperature superconductors (HTSs) in motors and generators and discuss methods for using trapped-flux (TF) HTSs in motors and generators that have been recently investigated in our laboratory. We examine the expected performance of a brushless motor/generator that uses TF bulk HTSs to provide magnetomotive force, where the stator windings are used to create the TF. A key feature is the use of dysprosium for the stator and rotor cores.

  5. Rare earth optogalvanic spectroscopy: preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Destro, Marcelo G.; Neri, Jose W.; Rodrigues, Nicolau A.S.; Silveira, Carlos A.B.; Riva, Rudimar [Instituto de Estudos Avancados (IEAv/EFO), Sao Jose dos Campos, SP (Brazil). Div. de Fotonica]. E-mail: destro@ieav.cta.br; Victor, Alessandro R. [Instituto Tecnologico de Aeronautica (ITA), Sao Jose dos Campos, SP (Brazil)

    2008-07-01

    The IEAv has special interest in the studies of rare earth isotope applications in laser medium and integrated optics as well as aerospace research. We are starting to work with Ytterbium, Erbium, Dysprosium and Neodymium laser selective photoionization research. This paper describes the preliminary results of emission and optogalvanic spectroscopy obtained from a Neodymium hollow cathode lamps. Furthermore these results were used to setup our laser systems to work to leads a Nd isotopes selective laser photoionization. (author)

  6. Rotating Magnetocaloric Effect in an Anisotropic Molecular Dimer.

    Science.gov (United States)

    Lorusso, Giulia; Roubeau, Olivier; Evangelisti, Marco

    2016-03-01

    In contrast to the mainstream research on molecular refrigerants that seeks magnetically isotropic molecules, we show that the magnetic anisotropy of dysprosium acetate tetrahydrate, [{Dy(OAc)3 (H2 O)2}2]⋅4 H2O (1), can be efficiently used for cooling below liquid-helium temperature. This is attained by rotating aligned single-crystal samples in a constant applied magnetic field. The envisioned advantages are fast cooling cycles and potentially compact refrigerators.

  7. Energy dependence of thermoluminescent response of CaSO{sub 4}:Dy, LiF:Mg and micro LiF:Mg,Ti in clinical beams of electrons by using different simulator objects; Dependencia energetica da resposta TL de dosimetros de CaSO{sub 4}:Dy, LiF:Mg e microLiF:Mg,Ti em feixes clinicos de eletrons utilizando diferentes objetos simuladores

    Energy Technology Data Exchange (ETDEWEB)

    Bravim, Amanda; Campos, Leticia Lucente, E-mail: abravin@ipen.b, E-mail: rsakuraba@einstein.b, E-mail: lcrodri@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Sakuraba, Roberto K.; Cruz, Jose Carlos da, E-mail: rsakuraba@einstein.b, E-mail: josecarlosc@einstein.b [Hospital Israelita Albert Einstein (HIAE), Sao Paulo, SP (Brazil)

    2011-10-26

    Yet not so widely applied in radiotherapy, the calcium sulfate doped with dysprosium (CaSO{sub 4}:Dy) is used in radioprotection and studies has been demonstrated its great potential for the dosimetry in radiotherapy. This work evaluates the energy dependence of the thermoluminescent answer of the CaSO{sub 4}:D, LiF:Mg,Ti (TLD-100) and micro LiF:Mg,Ti in clinical beams of electrons by using water simulators, PMMA and solid water

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

    Energy Technology Data Exchange (ETDEWEB)

    Kwolek, Emma J. [Iowa State Univ., Ames, IA (United States)

    2016-10-25

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

  9. New Realities: Energy Security in the 2010s and Implications for the U.S. Military

    Science.gov (United States)

    2014-01-01

    of the main renewable energy technologies (RETs)—such as wind power or photovoltaics (PV)—used in electric power generation. Wind turbines , PV... turbines and e-vehicle motors, and neodymium is a light REE used in the same applications as dysprosium as well as in e-vehicle batteries. China supplies...energy sector. For example, supercomputing is a key component to seismic analysis; refineries are increasingly driven by Supervisory Control and Data

  10. Properties of strongly dipolar Bose gases beyond the Born approximation

    CERN Document Server

    Ołdziejewski, Rafał

    2016-01-01

    Strongly dipolar Bose gases can form liquid droplets stabilized by quantum fluctuations. In theoretical description of this phenomenon, low energy scattering amplitude is utilized as an effective potential. We show that for magnetic atoms corrections with respect to Born approximation arise, and derive modified pseudopotential using realistic interaction model. We discuss the resulting changes in collective mode frequencies and droplet stability diagram. Our results are relevant for recent experiments with erbium and dysprosium atoms.

  11. Thermokinetics of Liquid-Liquid Reaction of Dy(NO3)3 with Histidine

    Institute of Scientific and Technical Information of China (English)

    李仲谨; 陈三平; 房艳; 高胜利

    2003-01-01

    The thermokinetics of liquid-liquid reaction of dysprosium nitrate with histidine were studied using a microcalorimeter. On the basis of experimental and calculated results, three thermodynamic parameters (the activation enthalpy, the activation entropy and the activation free energy), the rate constant, three kinetic parameters (the activation energy, the pre-exponential constant and the reaction order) were obtained. On the basis of thermodynamics and kinetics, the formation reaction of the complex was discussed.

  12. China rare earth market review

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Rare earth market remained weak recently. Dealings of light and heavy rare earth products were sluggish. Demand for didymium and dysprosium related products was soft and purchasers were not interested in replenishing their stocks. The market of NdFeB magnetic materials and phosphors remained inactive. Meanwhile, ceramic, catalyst and polishing powder industries were weak. Affected by global economical recession, export market of rare earth remained weak.

  13. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    November 20-30.2011 Weak demand resulted in the slack rare market. Consumers did not intend to rep earth enish inventories yet and transactions of rare earth products were stagnant. The market of didymium-related products was in the doldrums. Demand for dysprosium-related products was sluggish. Inquiries for europium oxide (99.9%) were few and dealings of the product were difficult.

  14. High Density Ion Implanted Contiguous Disk Bubble Technology.

    Science.gov (United States)

    1985-09-01

    of 0.504pm. A second melt producing films of (Sm1 2Lu 1.7Tm0 . 1( FeGa )5O1 2) was also developed for sub- micron bubbles. Data from films typical of the...Dysprosium film composition was to be (Sm0 .3 Dyl.1 Gd 0 .4Lu0 .7( FeGa ) 50 2) which would have magnetostriction coefficients of -2.8x10 6 and a mismatch of

  15. Single molecule magnet behaviour in a rare trinuclear {Cr(III)Dy} methoxo-bridged complex.

    Science.gov (United States)

    Car, Pierre-Emmanuel; Favre, Annaïck; Caneschi, Andrea; Sessoli, Roberta

    2015-09-28

    The reaction of the chromium(iii) chloride tetrahydrofuran complex with the dipivaloylmethane ligand, the lanthanide alcoholic salt DyCl3·CH3OH and the 1,1,1-tris(hydroxymethyl)-ethane ligand resulted in the formation of a new trinuclear chromium-dysprosium complex. Magnetic investigations revealed that the new 3d-4f complex exhibits single molecule magnet behaviour.

  16. Microstructural characterization aluminium alloys from the addition of boron; Caracterizacao microestrutural de ligas de aluminio a partir da adicao de boro

    Energy Technology Data Exchange (ETDEWEB)

    Nunes, A.G.P.; Pipano, T.F.; Mota, M.A.; Mariano, N.A.; Ramos, E.C.T. [Universidade Federal de Alfenas (UNIFAL), Pocos de Caldas, MG (Brazil). Instituto de Ciencias e Tecnologia

    2014-07-01

    In the electrical industry, the aluminum becomes attractive because it has excellent characteristics for transmitting electricity. The liquid aluminum has in its composition transition elements (zirconium, titanium, vanadium and chromium) that interfere negatively on the quality of the product. The addition of aluminum-boron alloys have been used to remove transition metals through the formation of borides, enabling an increase in electrical conductivity. However, no detailed reports of reactions between boron, transition metals and primary aluminum engines. However, the objective is to determine the stoichiometric composition that enables an increase in electrical conductivity of an aluminum alloy. Samples with different concentrations of boron were characterized by optical emission spectrometry, electrical conductivity and X-ray diffraction. The addition of boron in excess reduces the time in the formation of borides, and enable an increase in electrical conductivity. (author)

  17. Electric arc surfacing on low carbon steel: Structure and properties

    Science.gov (United States)

    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.

  18. New binder phases for the consolidation of TiB{sub 2} hardmetals

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, R. [Univ. Panamericana, Mexico D.F. (Mexico); Barandika, M.G. [Centro de Estudios e Investigaciones Tecnicas de Guipuzcoa (CEIT), San Sebastian (Spain). Dept. de Materiales; Ona, D. [Centro de Estudios e Investigaciones Tecnicas de Guipuzcoa (CEIT), San Sebastian (Spain). Dept. de Materiales; Sanchez, J.M. [Centro de Estudios e Investigaciones Tecnicas de Guipuzcoa (CEIT), San Sebastian (Spain). Dept. de Materiales; Villellas, A. [Centro de Estudios e Investigaciones Tecnicas de Guipuzcoa (CEIT), San Sebastian (Spain). Dept. de Materiales; Valea, A. [Escuela de Ingenieria Tecnica Industrial, Dept. de Ingenieria Qumica y del Medio Ambiente, Bilbao (Spain); Castro, F. [Centro de Estudios e Investigaciones Tecnicas de Guipuzcoa (CEIT), San Sebastian (Spain). Dept. de Materiales

    1996-10-15

    New TiB{sub 2}-based cermets have been consolidated by hot isostatic pressing of powder mixtures of TiB{sub 2} and metallic alloys based on Fe, Ni and Co additions. Relevant thermodynamic aspects of the systems B-Ti-Ni, B-Ti-Fe and B-Ti-Co, essential for avoiding the formation of extremely brittle secondary borides, especially the secondary boride M{sub 23}B{sub 6}, are discussed in this work. The role of contaminants like oxygen, carbon and nitrogen, which can also lead to the formation of these compounds is also explained. The hardness, toughness and cutting behaviour of the cermets produced with these new binder phases are comparable with the highest commercial WC-Co grades. (orig.)

  19. Phase transformations in Mo-doped FINEMETs

    Energy Technology Data Exchange (ETDEWEB)

    Silveyra, Josefina M., E-mail: jsilveyra@fi.uba.a [Lab. de Solidos Amorfos, INTECIN, FIUBA-CONICET, Paseo Colon 850, (C1063ACV) Buenos Aires (Argentina); Illekova, Emilia; Svec, Peter; Janickovic, Dusan [Institute of Physics SAS, Dubravska cesta 9, 845 11 Bratislava (Slovakia); Rosales-Rivera, Andres [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Manizales (Colombia); Cremaschi, Victoria J. [Lab. de Solidos Amorfos, INTECIN, FIUBA-CONICET, Paseo Colon 850, (C1063ACV) Buenos Aires (Argentina)

    2010-06-15

    In this paper, the phase transformations occurring during the crystallization process of FINEMETs in which Nb has been gradually replaced by Mo have been studied by a variety of techniques including DSC, DTA, TGA, XRD and TEM. The thermal stability of the alloy was deteriorated as a consequence of Mo's smaller atomic size. The gradual replacement of Nb by Mo reduced the onset temperature of Fe-Si and of the borides. The Curie temperature of the amorphous phase slightly decreased from 594 K for x=0 to 587 K for x=3. The borides compounds Fe{sub 2}B and Fe{sub 23}B{sub 6} as well as the (Nb,Mo){sub 5}Si{sub 3} phase were found to precipitate in the second and third crystallization.

  20. 渗硼

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    [ 篇名 ]A method of making boride and vitreous compound by powder metallurgy,[ 篇名 ] Ceramic-metal composites obtained by reactive prcssurclcss countcrflow inlitration/pcnctration (RPCI) of a ceramic substrate with two different metallic infiltrants,[篇名] Characterization of Directionally Solidified B{sub}4C-TiB{sub)2 and B{sub)4C-SiC Eutectic Composites Prepared by Floating-Zone Method,[篇名] Corrosion resistance of an iron base boridc cermets with oxide surface layers n a molten al alloy,[ 篇名 ] Crack propagation characteristics and fracture surface energy of boride conners,[篇名] Deposition of hard and/or corrosion resistant, single and multielement coatings on ferrous and nonferrous alloys in fluidized bed reactor,[ 篇名] Deposition of protective coatings on tungstenfree hard alloys。

  1. “IMPROVEMENT IN TRIBOLOGICAL PROPERTIES BY IMPROVING GEOMETRY OF REINFORCEMENT PARTICLES”

    Directory of Open Access Journals (Sweden)

    SHIVAJI V.GAWALI

    2011-12-01

    Full Text Available The volume fraction of the heavier Titanium Di-boride particles is controlled by inertial forces upon centrifugal force processing the semisolid composite. Titanium Di-boride particles are modeled as tetrahedron particles subject to a drag force in a Stoke flow. The equation of motion for the particles under the applied centrifugalforces is solved mathematically assuming a Gaussian diameter size distribution with a spatial uniform random distribution of particles in the sample. The effect of the geometry of the particles is also important. It is observed that the Penetration capability of reinforcement particles is dependent on the shape and the geometryof the particles. Drag force is kept at the minimum by adopting tetrahedron shape particles. It is possible to understand and control the experimental conditions to obtain an appropriate functionally-graded aluminum matrix by centrifugal casting for high wear resistance applications.

  2. Liquid Phase Sintering of Highly Alloyed Stainless Steel

    DEFF Research Database (Denmark)

    Mathiesen, Troels

    1996-01-01

    Liquid phase sintering of stainless steel is usually applied to improve corrosion resistance by obtaining a material without an open pore system. The dense structure normally also give a higher strength when compared to conventional sintered steel. Liquid phase sintrering based on addition...... of boride to AISI 316L type steels have previously been studied, but were found to be sensitive to intergranular corrosion due to formation of intermetallic phases rich in chromium and molybdenum. In order to improve this system further, new investigations have focused on the use of higher alloyed stainless...... steel as base material. The stainless base powders were added different amounts and types of boride and sintered in hydrogen at different temperatures and times in a laboratory furnace. During sintering the outlet gas was analyzed and subsequently related to the obtained microstructure. Thermodynamic...

  3. Plasma boronizing of Ti6AlV4 using solid precursors by double glow plasma alloying technique

    Institute of Scientific and Technical Information of China (English)

    QIN Lin; QU Jun-zhi; LIN Nai-ming; FAN Ai-lan; CHANG Da-qing; TANG Bin

    2006-01-01

    Solid state B-offerings (FeB compound) were used for plasma-assisted boronizing on Ti6Al4V alloy by double glow discharge plasma alloying technique (DGPSA). During all experiment processing there was no harmful and toxic. The thickness and morphology, phase formation, elements concentrations and wear properties of boride layers were examined by means of optical microscopy, Vickers microhardness, X-ray diffraction, glow discharge optical emission spectroscopy and Ball-disk wear tests. The results show that friction coefficient of boride alloying samples versus corundum ball is lower than that of Ti6Al4V samples, as well as wear rate. This indicates that plasma-assisted boronizing of Ti6Al4V alloy has a high potential for industrial applications under tribological conditions.

  4. Ceramic fibers from Si-B-C polymer precursors

    Science.gov (United States)

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

    1993-01-01

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

  5. Atomic-scale Modelling of Electro-catalytic Surfaces and Dynamic Electrochemical Interfaces

    DEFF Research Database (Denmark)

    Hansen, Martin Hangaard

    This dissertation addresses numerical calculations on the atomic scale to study catalytic surfaces for electrochemistry. The first half of the thesis deals with calculations on the properties of catalytic surfaces, using well known methodology, whereas the second half of the thesis deals...... with the development of new methodology to explicitly include the electrolyte in the atomic scale calculations. Chapter 3 presents calculations on contracted and reconstructed platinum surfaces, which are relevant for development of catalysts for proton exchange membrane fuel cells. Correlation of the results...... evolution reaction. The results show that molybdenum carbides and borides have reactive surfaces, which is not in consistency with their high catalytic activity. A possible active facet is suggested for the molybdenum boride. It is likely, however, that other unexplored active sites, surface terminations...

  6. Compressibility of AlB sub 2 -type transition metal diborides

    CERN Document Server

    Pereira, A S; Jornada, J A; Leger, J M; Haines, J

    2002-01-01

    The pressure behaviour of a series of transition metal borides has been studied both experimentally and by means of ab initio calculations. X-ray diffraction patterns measured up to approx 50 GPa for VB sub 2 and ZrB sub 2 show no obvious phase transition. Bulk moduli of 322 and 317 GPa, respectively, were obtained using a Murnaghan equation of state. Hartree-Fock LCCO (linear combination of crystal orbitals) calculations performed for TiB sub 2 have allowed its compression behaviour to be studied. The bulk modulus obtained (292 GPa) and the proposed important contribution of the interlayer interaction to the elastic behaviour under high pressure are consistent with the experimental results for the other borides.

  7. Perspectives of High-Temperature Thermoelectric Applications and p-type and n-type Aluminoborides

    Science.gov (United States)

    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. Peculiar structure and tensile strength of WB4: nonstoichiometric origin

    Directory of Open Access Journals (Sweden)

    Huiyang Gou

    2012-03-01

    Full Text Available Tungsten tetraboride (WB4 is experimentally considered as potentially superhard material and is therefore expected to have highly structural stability and enhanced resistance against plastic deformation and failure. The examinations of bond-deformation mechanism suggest a significantly soft bond-deformation pattern induced by ionic W-B bonding for nominal WB4 in experiments, largely responsible for the limitation of its strength and structural integrity. Computations on the structures and mechanical properties for WB4 show a novel thermodynamically favored MoB4-type phase with excellent mechanical properties and remarkable incompressibility along c direction. The illustrations of nonstoichiometry and x-ray diffraction spectra rationalize the experimental observation of nominal composition WB4 as defective tungsten borides (W1-xB3 (x0.25. The results provide new insight into the real structural and mechanical properties of tungsten borides.

  9. EXPERIMENTAL PHASE EQUILIBRIA OF SELECTED BINARY, TERNARY, AND HIGHER ORDER SYSTEMS. PART 4. THE PHASE DIAGRAM W-B-C

    Science.gov (United States)

    system and the mutual solubilities between carbide and boride phases are small. The solid state sections (򒾐C) are characterized by two- phase ... equilibria existing between the phase pairs W2B + W2C, W2B + WC, WC + WB, WB + C, W2B5 + C, W2B5 + B4C, and WB approximately 4 + B4C. The two-phase

  10. Computational analysis of stable hard structures in the Ti-B system.

    Science.gov (United States)

    Li, Pengfei; Zhou, Rulong; Zeng, Xiao Cheng

    2015-07-22

    The lowest energy crystalline structures of various stoichiometric titanium boride (Ti-B) intermetallic compounds are sought based on density functional theory combined with the particle-swarm optimization (PSO) technique. Besides three established experimental structures, i.e., FeB-type TiB, AlB2-type, and Ta3B4-type Ti3B4, we predict additional six metastable phases at these stoichiometric ratios, namely, α- and β-phases for TiB, TiB2, and Ti3B4, respectively. Moreover, we predict the most stable crystalline structures of four new titanium boride compounds with different stoichiometric ratios: Ti2B-PSA, Ti2B3-PSB, TiB3-PSC, and TiB4-PSD. Notably, Ti2B-PSA is shown to have lower formation energy (thus higher stability) than the previously proposed Al2Cu-type Ti2B. The computed convex-hull and phonon dispersion relations confirm that all the newly predicted Ti-B intermetallic crystals are thermodynamically and dynamically stable. Remarkably, the predicted α-TiB2 and β-TiB2 show semi-metal-like electronic properties and possess high Vickers hardnesses (39.4 and 39.6 GPa), very close to the lower limit of superhard materials (40 GPa). Analyses of band structure, density of states, electronic localization function, and various elastic moduli provide further understanding of the electronic and mechanical properties of the intermetallic titanium borides. We hope the newly predicted hard intermetallic titanium borides coupled with desirable electronic properties and high elastic modulus will motivate future experimental synthesis for applications such as high-temperature structural materials.

  11. Microstructure and Phase Formation in a Rapidly Solidified Laser-Deposited Ni-Cr-B-Si-C Hardfacing Alloy

    OpenAIRE

    Hemmati, Ismail; Ocelik, Vaclav; Csach, Kornel; Hosson, Jeff Th.M.; 296099953

    2014-01-01

    In this study, microstructural evolutions and phase selection phenomena during laser deposition of a hardfacing Ni-Cr-B-Si-C alloy at different processing conditions are experimentally investigated. The results show that even minor variations in the thermal conditions during solidification can modify the type and morphology of the phases. Higher undercoolings obtained at faster cooling rates suppressed the primary borides and encouraged floret-shape mixtures of Ni and Cr5B3 via a metastable r...

  12. Successive Boronizing and Austempering for GGG-40 Grade Ductile Iron

    Institute of Scientific and Technical Information of China (English)

    Murat Baydogan; Seckin Izzet Akray

    2009-01-01

    Boronizing and austempering were successively applied to a GGG-40 grade ductile iron in order to combine the advantages of both process in a single treatment. This new procedure formed a 30 μm thick boride layer on the surface with subsurface matrix structure consisted of acicular ferrite and retained austenite. Reciprocating wear tests showed that successive boronizing and austempering exhibited considerably higher wear resistance than conventional boronizing having a subsurface matrix structure consisting of ferrite and pearlite.

  13. Method to produce catalytically active nanocomposite coatings

    Energy Technology Data Exchange (ETDEWEB)

    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.

  14. Hybrid fiber and nanopowder reinforced composites for wind turbine blades

    Directory of Open Access Journals (Sweden)

    Nikoloz M. Chikhradze

    2015-01-01

    Full Text Available The results of an investigation into the production of wind turbine blades manufactured using polymer composites reinforced by hybrid (carbon, basalt, glass fibers and strengthened by various nanopowders (oxides, carbides, borides are presented. The hybrid fiber-reinforced composites (HFRC were manufactured with prepreg technology by molding pre-saturated epoxy-strengthened matrix-reinforced fabric. Performance of the manufactured composites was estimated with values of the coefficient of operating condition (COC at a moderate and elevated temperature.

  15. Research on YB68 for Microwave Acoustic Crystals

    Science.gov (United States)

    1974-11-01

    techniques. Comparisons were made among sapphire crystals grown by Verneuil , Czochralski, and chemical vapor deposition tech- niques, and MgAlsO, spinel grown...long memory time, microwave ultrasonic delay lines. Information on sapphire , spinel, yttrium aluminum garnet, and yttrium boride is presented. At...and for longitudinal waves in P-rhombohedral boron and Al 0 3 ( sapphire ). At present, delay lines are constructed prircipally from sapphire , using

  16. Elaboration de revêtements sur acier inoxydable: simulation de la fusion par irradiation laser, caractérisation structurale, mécanique et tribologique.

    OpenAIRE

    Avril, Ludovic

    2003-01-01

    A pulsed Nd-YAG laser is used to irradiate and alloy X30Cr13 stainless steel by surface melting, with incorporation of boron or hexagonal boron nitride (h-BN), and to obtain thick coatings: multiphase borided alloys or metal-ceramic composites. The metallographic analyses allow to determine the thickness for each coating (melting zone) and reveal characteristic solidification microstructures: planar front and cellular dendrites. Optical characteristics of the laser beam are measured: divergen...

  17. Utilizing Interfaces for Nano- and Micro-scale Control of Thermal Conductivity

    Science.gov (United States)

    2015-08-17

    performance of these promising materials by 50%. Ballmilling and spark plasma sintering (SPS) processes were investigated to try to lower the thermal...samples fabricated through the spark plasma sintering”, Mater Renew Sustain Energy, 3, 31-1 31-6 (2014). DOI: 10.1007/s40243-014-0031-8 9. O. Sologub...Takao Mori, Gordon Research Conference in Solid State Chemistry, “Development of nov el borides, silicides, sulfides, and nitrides as effective

  18. Manhattan Project Technical Series The Chemistry of Uranium (I) Chapters 1-10

    Energy Technology Data Exchange (ETDEWEB)

    Rabinowitch, E. I. [Argonne National Laboratory (ANL), Argonne, IL (United States); Katz, J. J. [Argonne National Laboratory (ANL), Argonne, IL (United States)

    1946-09-30

    This constitutes Chapters 1 through 10. inclusive, of The Survey Volume on Uranium Chemistry prepared for the Manhattan Project Technical Series. Chapters are titled: Nuclear Properties of Uranium; Properties of the Uranium Atom; Uranium in Nature; Extraction of Uranium from Ores and Preparation of Uranium Metal; Physical Properties of Uranium Metal; Chemical Properties of Uranium Metal; Intermetallic Compounds and Alloy systems of Uranium; the Uranium-Hydrogen System; Uranium Borides, Carbides, and Silicides; Uranium Nitrides, Phosphides, Arsenides, and Antimonides.

  19. Low temperature synthesis of low thermionic work function (La{sub x}Ba{sub 1−x})B{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Hasan, M.M., E-mail: Muhammad.Hasan@uon.edu.au; Cuskelly, D.; Sugo, H.; Kisi, E.H.

    2015-07-05

    Highlights: • The mixed boride La{sub x}Ba{sub 1−x}B{sub 6} was successfully produced using a boron carbide method. • Following synthesis samples sintered at 1950 °C yielded ∼85% (wt%) (La{sub 0.31}Ba{sub 0.69})B{sub 6}. • The Richardson work function for this boride mixture was found to be only 1.03 eV. - Abstract: This study presents investigations of the microstructure, morphology and emission properties of the promising thermionic material (La{sub x}Ba{sub 1−x})B{sub 6}. The material was synthesised by solid-state reaction without post-synthesis purifications. Powder X-ray diffraction revealed that samples prepared at a temperature ⩾1500 °C had formed a significant proportion of solid solution (above 54 mass%). Subsequent sintering at 1950 °C caused the formation of a mixture of three solid solutions with the dominant phase being (La{sub 0.31}Ba{sub 0.69})B{sub 6} ∼85% (by mass). The Richardson work function and emission constant for this boride mixture were found to be 1.03 eV and 8.44 × 10{sup −6} A cm K{sup −2} respectively.

  20. Microstructure characteristics of high borated stainless steel fabricated by hot-pressing sintering

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xuan; Wang, Mingjia, E-mail: mingjiawangysu@126.com; Zhao, Hongchang

    2016-04-25

    The present study investigated the microstructure of powder metallurgy (P/M) high borated stainless steel through hot-pressing sintering in a temperature range of 1000–1150 °C within 30 min under 30 MPa. Microstructure and phase examinations were carried out by applying scanning electron microscope, electron backscatter diffraction and X-ray diffraction analysis. The results of as-atomized powders demonstrated that many powders kept egg-type structure with an austenite outer layer and the eutectic borides were much finer than those in traditional cast products. Microstructure studies revealed that borides suffered Ostwald ripening and were significantly influenced by the sintering temperature. Orientation maps indicated that the inter-particle contact areas consisted of equiaxed grains and the regions consisting of large elongated grains partly inherited the microstructure characteristics of as-atomized powder particles. Furthermore, the mechanisms governing the morphological changes in microstructure were discussed. - Highlights: • Near-complete densification could be obtained through hot-pressing sintering. • There was no phase transformation and present phases were M{sub 2}B and austenite. • Borides suffered Ostwald ripening and were significantly influenced by temperature. • Inter-particle contact areas consisted of equiaxed grains for recrystallization. • Deformation-free zones exhibited elongated grains for dendritic arms coarsening.

  1. Peculiar features of metallurgical processes at plasma-arc spraying of coatings, made of steel wire with powder fillers B4C and B4C+ZrO2

    Directory of Open Access Journals (Sweden)

    Георгій Михайлович Григоренко

    2016-11-01

    Full Text Available The interaction of metallurgical processes occurring in plasma-arc spraying between the steel shell and the carbide fillers of B4C and B4C cored wires with the addition of nanocrystalline ZrO2 powder has been analyzed. Iron-boron compounds alloyed with carbon are formed in ingots as a result of ferritiс coating of wire interacrion with fillers while the ferritic matrix contains boride and carboboride eutectics. Average microhardness of the carboboride compounds and the matrix is high – 17,78; 16,40 and 8,69; 9,95 GPa for the ingots with с B4C and B4C+ZrO2 respectively. The best quality coatings with low porosity (~1%, lamellar structure consisting of ferrite matrix reinforced with dispersed Fe borides, were obtained at a higher heat input (plasmatron current 240-250 A. The average amount of oxides in the coatings makes 15%. 0,5% addition of nanopowder ZrO2 accelerates dispersed iron-boron compounds forming, promotes their uniform distribution in the structure and improves coating microhardness up to 7,0 GPa. Application of the differential thermal analysis method to simulate the interaction processes between the steel shell and the filler during the heating of wire in the shielding gas makes it possible to promote formation of new phases (borides and carboborides of iron and to predict the phase composition of the coatings

  2. Influence of Lanthanum on Tribological Properties and Microstructure of Laser Clad B+Fe+Si Composite Coatings

    Institute of Scientific and Technical Information of China (English)

    程西云; 谢学兵; 蒋松

    2004-01-01

    The effects of rare earth ferrosilicon on the microstructure and anti-wear properties of laser-clad Fe-based alloy coating were investigated. The composition of Fe,B4C and rare earth ferrosilicon powders with different contents of lanthanum were clad onto a 45# carbon steel substrate. Microstructural features,chemical compositions,phase structure,hardness,friction and wear properties by scanning electron microscopy(SEM),X-ray photoelectron microscopy(XPS),hardness tester,block-on-ring friction and wear tester of the clad coating were determined. Experimental results show that the friction coefficient of the clad coating doped with rare earth ferrosilicon is reduced while the wear resistance of clad coating doped with rare earth ferrosilicon is enhanced. When the content of lanthanum increases to 1.92%,the clad coating shows the best anti-wear ability,and as the content of lanthanum exceeds 1.92%,the wear weight loss increases quickly. The rare earth ferrosilicon to be doped in the clad coatings helps to disperse the boride phase(Fe2B,FeB,B4C) particles and refine the grain of boride phase. The enhancement of clad coating's wear resistance is due to the existence of dispersed boride phases.

  3. Wear Behaviour of Plasma Paste Boronized of AISI 8620 Steel with Borax and B2O3 Paste Mixtures

    Institute of Scientific and Technical Information of China (English)

    Ibrahim Gunes

    2013-01-01

    In the present study,AISI 8620 steel was plasma paste boronized (PPB) by using paste mixtures with different borax and B2O3 percentages.The PPB process was carried out in a DC plasma system at 973,1023 and 1073 K for 5 h in a gas mixture with 70% H2-30% Ar under a constant pressure of 103 Pa (10 mbar).The thickness of boride layers ranged from 15.9 to 53.6 μm depending on the temperature and process time.The hardness of the borides formed on the surface of the steel substrate and unborided steel substrate were 1648-1924 HV0.05 and 226 HV0.05,respectively.X-ray diffraction analysis of the boride layers on the surface of the samples were obtained for FeB and Fe2B phases.The wear tests on the steel were performed by using a ball-on-disc test device at room temperature with applied load of 10 N and with a shear velocity of 0.2 m/s.Wear test results showed that the highest value of wear rate was observed in the unborided sample while the lowest wear rate was observed in the PPB samples with 30% borax + 70% B4C paste at 1073 K for 5 h.

  4. Glass microspheres for medical applications

    Science.gov (United States)

    Conzone, Samuel David

    Radioactive dysprosium lithium borate glass microspheres have been developed as biodegradable radiation delivery vehicles for the radiation synovectomy treatment of rheumatoid arthritis. Once injected into a diseased joint, the microspheres deliver a potent dose of radiation to the diseased tissue, while a non-uniform chemical reaction converts the glass into an amorphous, porous, hydrated dysprosium phosphate reaction product. The non-radioactive, lithium-borate component is dissolved from the glass (up to 94% weight loss), while the radioactive 165Dy reacts with phosphate anions in the body fluids, and becomes "chemically" trapped in a solid, dysprosium phosphate reaction product that has the same size as the un-reacted glass microsphere. Ethylene diamine tetraacetate (EDTA) chelation therapy can be used to dissolve the dysprosium phosphate reaction product after the radiation delivery has subsided. The dysprosium phosphate reaction product, which formed in vivo in the joint of a Sprague-Dawley rat, was dissolved by EDTA chelation therapy in 100 Gy) of localized beta radiation to a treatment site within the body, followed by complete biodegradability. The non-uniform reaction process is a desirable characteristic for a biodegradable radiation delivery vehicle, but it is also a novel material synthesis technique that can convert a glass to a highly porous materials with widely varying chemical composition by simple, low-temperature, glass/solution reaction. The reaction product formed by nonuniform reaction occupies the same volume as the un-reacted glass, and after drying for 1 h at 300°C, has a specific surface area of ≈200 m2/g, a pore size of ≈30 nm, and a nominal crushing strength of ≈10 MPa. Finally, rhenium glass microspheres, composed of micron-sized, metallic rhenium particles dispersed within a magnesium alumino borate glass matrix were produced by sintering ReO2 powder and glass frit at 1050°C. A 50 mg injection of radioactive rhenium glass

  5. Magnetic and structural properties of nano sized Dy-doped cobalt ferrite synthesized by co-precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Karimi, Z., E-mail: Zahra_kr64@yahoo.com [Department of Materials Engineering, Institute of Mechanical Engineering, University of Tabriz, Tabriz 51666-16471 (Iran, Islamic Republic of); Mohammadifar, Y.; Shokrollahi, H. [Electroceramics Group, Department of Materials Science and Engineering, Shiraz University of Technology, Shiraz (Iran, Islamic Republic of); Asl, Sh. Khameneh [Department of Materials Engineering, Institute of Mechanical Engineering, University of Tabriz, Tabriz 51666-16471 (Iran, Islamic Republic of); Yousefi, Gh. [Center for Pharmaceutical Nanotechnology and Biomaterials, Pharmaceutical Sciences Research Center, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz (Iran, Islamic Republic of); Department of Pharmaceutics, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz (Iran, Islamic Republic of); Karimi, L. [Materials Science and Engineering Department, Islamic Azad University Ahvaz Branch, Ahvaz (Iran, Islamic Republic of)

    2014-06-01

    Regarding the various applications of cobalt ferrite as a magnetic ceramic in various scientific and industrial categories, it is essential to modify and optimize its microstructural and magnetic features. Chemical composition (doped elements and their quantities) is a determining factor which has been studied in this research. For this purpose, cobalt-dysprosium ferrite ceramic nanoparticles with the chemical formula Co{sub 1−x}Dy{sub x}Fe{sub 2}O{sub 4} (x=0, 0.01, 0.03, 0.05, 0.1) were synthesized by the co-precipitation chemical method and then analyzed from the structural and magnetic perspectives. The desirable spinel phase formation was confirmed via x-ray diffractometry, and the other crystallographic parameters and cation distribution were calculated. The microscopic image of the samples showed 15 nm particles. The type and strength of the interionic bonds were determined by infrared spectroscopy. The hysteresis loop of the material was affected noticeably by doped elements as the room temperature saturation magnetization was decreased, but the residual magnetization and coercivity of ferrite were promoted by 50 and 150% after adding dysprosium, respectively. The maximum anisotropy constant, which is equal to 19.1 erg/g for undoped cobalt ferrite, was increased to 45.2 erg/g by doping 0.05 dysprosium. It is worth mentioning that introducing dopants into the lattice led to a great decrease in Curie temperature. - Highlights: • Magnetic and structural studies of Dy{sup 3+}–Co–ferrite are investigated. • Simple co-precipitation method involving less energy and low-cost is used. • The nanoparticles with high coercivity, magnetization and loop area are obtained. • The composition Co{sub 0.95}Dy{sub 0.05}Fe{sub 2}O{sub 4} has the maximum coercivity and high residual magnetization.

  6. Anisotropic expansion of a thermal dipolar Bose gas

    CERN Document Server

    Tang, Yijun; Burdick, Nathaniel Q; DiSciacca, Jack M; Petrov, Dmitry S; Lev, Benjamin L

    2016-01-01

    We report on the anisotropic expansion of ultracold bosonic dysprosium gases at temperatures above quantum degeneracy and develop a quantitative theory to describe this behavior. The theory expresses the post-expansion aspect ratio in terms of temperature and microscopic collisional properties by incorporating Hartree-Fock mean-field interactions, hydrodynamic effects, and Bose-enhancement factors. Our results extend the utility of expansion imaging by providing accurate thermometry for dipolar thermal Bose gases, reducing error in expansion thermometry from tens of percent to only a few percent. Furthermore, we present a simple method to determine scattering lengths in dipolar gases, including near a Feshbach resonance, through observation of thermal gas expansion.

  7. Anisotropic Expansion of a Thermal Dipolar Bose Gas.

    Science.gov (United States)

    Tang, Y; Sykes, A G; Burdick, N Q; DiSciacca, J M; Petrov, D S; Lev, B L

    2016-10-07

    We report on the anisotropic expansion of ultracold bosonic dysprosium gases at temperatures above quantum degeneracy and develop a quantitative theory to describe this behavior. The theory expresses the postexpansion aspect ratio in terms of temperature and microscopic collisional properties by incorporating Hartree-Fock mean-field interactions, hydrodynamic effects, and Bose-enhancement factors. Our results extend the utility of expansion imaging by providing accurate thermometry for dipolar thermal Bose gases. Furthermore, we present a simple method to determine scattering lengths in dipolar gases, including near a Feshbach resonance, through observation of thermal gas expansion.

  8. Neutron-scattering study of the magnetic structure of DyFe4Al8 and HoFe4Al8

    DEFF Research Database (Denmark)

    Paixao, J.A.; Silva, M.R.; Sørensen, S.Aa.

    2000-01-01

    at a slightly higher temperature (similar to 80 K) than the dysprosium. At a lower temperature higher-order harmonics of the modulation develop. The magnetic structure of the rare-earth at low temperature is a bunched elliptical cycloid, following the modulation of the Fe sublattice. Although...... the antiferromagnetic coupling of the rare-earth magnetic moments has long-range order, giving sharp magnetic satellites in the diffraction patterns, a non-negligible fraction of the 4f moment does not contribute to these peaks but appears as diffuse scattering beneath the Bra,og peaks. This indicates the presence...

  9. Synthesis and Optimization of the Sintering Kinetics of Actinide Nitrides

    Energy Technology Data Exchange (ETDEWEB)

    Drryl P. Butt; Brian Jaques

    2009-03-31

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

  10. Diagnostics of the plasma parameters based on the K X-ray line positions for various 4d and 4f metals

    Directory of Open Access Journals (Sweden)

    Szymańska Ewa

    2016-12-01

    Full Text Available This paper shows the theoretical predictions of the outer-shell ionization effect on the positions of Kα1,2, Kβ1,3, and K β2 X-ray lines for some 4d-transition metals (molybdenum and palladium and 4f rare-earth elements (dysprosium and ytterbium. The ionization energy shifts have been evaluated using the multiconfiguration Dirac-Fock method, containing Breit interaction and quantum electrodynamic (QED corrections. The presented results are important for obtaining the information about some parameters of plasma generated by different sources, especially by pulsed power machine and short-pulse lasers.

  11. Polyethylene terephthalate thin films; a luminescence study

    Science.gov (United States)

    Carmona-Téllez, S.; Alarcón-Flores, G.; Meza-Rocha, A.; Zaleta-Alejandre, E.; Aguilar-Futis, M.; Murrieta S, H.; Falcony, C.

    2015-04-01

    Polyethylene Terephthalate (PET) films doped with Rare Earths (RE3+) have been deposited on glass by spray pyrolysis technique at 240 °C, using recycled PET and (RE3+) chlorides as precursors. Cerium, terbium, dysprosium and europium were used as dopants materials, these dopants normally produce luminescent emissions at 450, 545, 573 and 612 nm respectively; the doped films also have light emissions at blue, green, yellow and red respectively. All RE3+ characteristic emissions were observed at naked eyes. Every deposited films show a high transmission in the visible range (close 80% T), films surfaces are pretty soft and homogeneous. Films thickness is around 3 μm.

  12. Rare (Earth Elements [score

    Directory of Open Access Journals (Sweden)

    Camilo Méndez

    2014-12-01

    Full Text Available Rare (Earth Elements is a cycle of works for solo piano. The cycle was inspired by James Dillon’s Book of Elements (Vol. I-V. The complete cycle will consist of 14 pieces; one for each selected rare (earth element. The chosen elements are Neodymium, Erbium, Tellurium, Hafnium, Tantalum, Technetium, Indium, Dysprosium, Lanthanium, Cerium, Europium, Terbium, Yttrium and Darmstadtium. These elements were selected due to their special atomic properties that in many cases make them extremely valuable for the development of new technologies, and also because of their scarcity. To date, only 4 works have been completed Yttrium, Technetium, Indium and Tellurium.

  13. China rare earth market review

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Rare earth market remained stagnant recently. The buyers did not show willingness to replenish raw materials affected by weak demand. Most persons in rare earth circle were not confident with the short-term rare earth market. Demand for didymium mischmetal was soft recently. The market of dysprosium related products was quiet and NdFeB magnet producers were inactive in the purchase. Phosphor market was stagnant as well. Buyers were cautious on replenishing the material. There were few inquiries for europium oxide (99.9%) in spot market and transactions were difficult.

  14. Optical characterization of CdSe/Dy3+-doped silica matrices

    Indian Academy of Sciences (India)

    P V Jyothy; P R Rejikumar; Thomas Vinoy; S Kartika; N V Unnikrishnan

    2010-11-01

    Cadmium selenide nanocrystals along with dysprosium ions are doped in silica matrices through sol–gel route. The optical bandgap and size of the CdSe nanocrystals are calculated from the absorption spectrum. The size of the CdSe nanocrystallites is also evaluated from the TEM measurements. The fluorescence intensities are compared for SiO2–Dy3+ and CdSe-doped SiO2–Dy3+. The fluorescence intensity of Dy3+ is considerably increased in the presence of CdSe nanocrystals.

  15. Anisotropic Expansion of a Thermal Dipolar Bose Gas

    Science.gov (United States)

    Tang, Y.; Sykes, A. G.; Burdick, N. Q.; DiSciacca, J. M.; Petrov, D. S.; Lev, B. L.

    2016-10-01

    We report on the anisotropic expansion of ultracold bosonic dysprosium gases at temperatures above quantum degeneracy and develop a quantitative theory to describe this behavior. The theory expresses the postexpansion aspect ratio in terms of temperature and microscopic collisional properties by incorporating Hartree-Fock mean-field interactions, hydrodynamic effects, and Bose-enhancement factors. Our results extend the utility of expansion imaging by providing accurate thermometry for dipolar thermal Bose gases. Furthermore, we present a simple method to determine scattering lengths in dipolar gases, including near a Feshbach resonance, through observation of thermal gas expansion.

  16. Persistent nonequilibrium dynamics of the thermal energies in the spin and phonon systems of an antiferromagnet.

    Science.gov (United States)

    von Reppert, A; Pudell, J; Koc, A; Reinhardt, M; Leitenberger, W; Dumesnil, K; Zamponi, F; Bargheer, M

    2016-09-01

    We present a temperature and fluence dependent Ultrafast X-Ray Diffraction study of a laser-heated antiferromagnetic dysprosium thin film. The loss of antiferromagnetic order is evidenced by a pronounced lattice contraction. We devise a method to determine the energy flow between the phonon and spin system from calibrated Bragg peak positions in thermal equilibrium. Reestablishing the magnetic order is much slower than the cooling of the lattice, especially around the Néel temperature. Despite the pronounced magnetostriction, the transfer of energy from the spin system to the phonons in Dy is slow after the spin-order is lost.

  17. Microscopic Calculation of IBM Parameters by Potential Energy Surface Mapping

    CERN Document Server

    Bentley, I

    2011-01-01

    A coherent state technique is used to generate an Interacting Boson Model (IBM) Hamiltonian energy surface that simulates a mean field energy surface. The method presented here has some significant advantages over previous work. Specifically, that this can be a completely predictive requiring no a priori knowledge of the IBM parameters. The technique allows for the prediction of the low lying energy spectra and electromagnetic transition rates which are of astrophysical interest. Results and comparison with experiment are included for krypton, molybdenum, palladium, cadmium, gadolinium, dysprosium and erbium nuclei.

  18. The magnetostriction of Tb, Dy and Ho revisited

    Energy Technology Data Exchange (ETDEWEB)

    Benito, L; Arnaudas, J I; Ciria, M; Fuente, C de la; Moral, A del [Departamento de Magnetismo de Solidos, Departamento de FIsica de la Materia Condensada-ICMA, Universidad de Zaragoza-CSIC, 50071 Zaragoza (Spain)

    2004-10-06

    In this paper we present re-analyses of magnetostriction measurements earlier performed in terbium, dysprosium and holmium single crystals. In the framework of the standard theory of single-ion crystal-electric-field and two-ion exchange magnetostrictions, we explain the thermal variation of the anisotropic saturation magnetostriction within the basal plane by considering high-order terms in the magnetoelastic energy. Using complementary basal-plane magnetic anisotropy measurements, we have been able to obtain the second- and fourth-order magnetoelastic coupling parameters associated with the orthorhombic distortion of the hexagonal plane for the above-mentioned three heavy rare earths.

  19. Thermokinetics on the reaction of formation of Dy[(C5H8NS2)3(C12H8N2)

    Institute of Scientific and Technical Information of China (English)

    GAO Shengli; CHEN Sanping; JIAO Baojuan; SHUAI Qi; SHI Qizhen

    2005-01-01

    The enthalpy change of formation of the reaction of hydrous dysprosium chloride meter. Thermodynamic parameters (the activation enthalpy, the activation entropy and the activation free energy), rate constant and kinetics parameters (the apparent activation energy, the pre-exponential constant and the reaction order) of the reaction have also been calculated. The enthalpy change of the solid-phase reaction at 298.15 K has been obtained as (53.59 ± 0.29)liquid-phase and solid-phase reaction indicated that the complex could only be synthesized in liquid-phase reaction.

  20. Magnetocaloric properties of rare-earth substituted DyCrO3

    Science.gov (United States)

    McDannald, A.; Jain, M.

    2015-07-01

    Recently, there has been a focus on the need for efficient refrigeration technology without the use of expensive or harmful working fluids, especially at temperatures below 30 K. Solid state refrigeration, based on the magnetocaloric effect, provides a possible solution to this problem. The rare-earth chromites (RCrO3), especially DyCrO3, with its large magnetic moment dysprosium ion, are potential candidates for such an application. The Dy3+ ordering transition at low temperatures (cooling power of 237 J/kg at 40 kOe and 5 K) indicates that this material system is well suited for low temperature (<30 K) solid state refrigeration applications.

  1. Heavy rotation – evolution of quadrupole collectivity centred at the neutron-rich doubly mid-shell nucleus {sup 170}Dy

    Energy Technology Data Exchange (ETDEWEB)

    Söderström, P.-A., E-mail: pasoder@ribf.riken.jp; Doornenbal, P.; Nishimura, S.; Baba, H.; Fukuda, N.; Inabe, N.; Isobe, T.; Kubo, T.; Kubono, S.; Suzuki, H.; Takeda, H. [RIKEN Nishina Center, 2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan); Regan, P. H. [Department of Physics, University of Surrey, Guildford, GU2 7XH (United Kingdom); National Physical Laboratory, Teddington, Middlesex, TW11 0LW (United Kingdom); Walker, P. M.; Carroll, R.; Lalkovski, S.; Lotay, G.; Patel, Z.; Podolyák, Zs.; Shand, C. M. [Department of Physics, University of Surrey, Guildford, GU2 7XH (United Kingdom); Watanabe, H. [IRCNPC, Beihang University, Beijing 100191 (China); School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China); and others

    2015-10-15

    In this contribution the low-excitation structural properties of the doubly mid-shell nucleus {sup 170}Dy are discussed, with a special empasis on the evolution of the ground state rotational band within the dysprosium isotopic chain. Recent results from an experiment with the EURICA setup at RIKEN are shown in the context of previous measurements at the PRISMA+CLARA as well as the PRISMA+AGATA setups at Laboratori Nazionali di Legnaro. A brief outlook on future planned measurements is also given.

  2. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    August 20-31, 2011 Rare earth market did not show the sign of picking-up and remained stagnant recently. Most suppliers continued to decrease their quoted price, but leading producers in northern and southern China did not adjust their quoted price. Most rare earth plants in southern China had not yet resumed production. Quoted price of didymium products swung and the quoted prices of dysprosium-related products were slipping affected by weak demand. Inquiries for europium oxide were decreasing affected by the slow phosphor market.

  3. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Rare earth market remained sluggish and quiet holistically recently. Didymium-related market was quiet and the consumers were hesitating in replenishing their inventories. Inquiries for dysprosium-related products were few and the transactions were inactive, Demand for europium oxide (99.99%) was weak and the trade was far from brisk. Baogang Rare Earth suspended production, which has a positive effect in stabilizing the whole rare earth market. But prices of rare earth products did not go up rapidly. This means there were still large inventories in the market.

  4. Holmium-161 produced using 11.6 MeV protons: A practical source of narrow-band X-rays

    Energy Technology Data Exchange (ETDEWEB)

    Stephens, Bryan J., E-mail: bryan.j.stephens@vanderbilt.ed [Department of Physics, Vanderbilt University, 6301 Stevenson Center, P.O. Box 351807 Station B, Nashville, TN 37235 (United States); Mendenhall, Marcus H., E-mail: marcus.h.mendenhall@vanderbilt.ed [Department of Electrical Engineering, Vandberbilt University, P.O. Box 351824 Station B, Nashville, TN 37235-1824 (United States)

    2010-10-15

    We present a novel technique to produce narrow-band X-rays by preparing {sup 161}Ho from the bombardment of dysprosium foil by 11.6 MeV protons. The activated foil produces predominantly 45-55 keV X-rays, which are suitable for activating iodinated radio-sensitizing agents (e.g. IUdR) for oncological therapy. We demonstrate that clinically useful quantities of the nuclide are easily produced with a medical cyclotron which is far from the current state of the art.

  5. Thermoluminescent characteristics of nano-structure hydroxyapatite:Dy

    Energy Technology Data Exchange (ETDEWEB)

    Ziaie, F. [Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of). Radiation Application Research School; Moein, N. Farhadi [Islamic Azad Univ. (Iran, Islamic Republic of). Central Tehran Branch; Shafaei, M. [Islamic Azad Univ. (Iran, Islamic Republic of). Science and Research Branch

    2014-12-15

    The thermoluminescence response of Dysprosium doped hydroxyapatite samples with different mol percentage of 0.5, 1 and 2 were studied and compared with the pure hydroxyapatite. The samples were objected to {sup 60}Co gamma rays irradiation with doses of 100 mGy to 10 Gy. The main peak in the sample glow curves were obtained at 310 C. The sensitivity of the 1 mol% Dy doped hydroxyapatite samples show the highest thermoluminescence response. Fading behavior of the irradiated samples was also studied. The experimental results show that the synthetic Dy-doped hydroxyapatite obtained by the hydrolysis method may be used in gamma radiation dosimetry.

  6. On the specific electrophysical properties of n-InSe single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Abdinov, A. Sh., E-mail: abdinov-axmed@yahoo.com [Baku State University (Azerbaijan); Babaeva, R. F., E-mail: babaeva-rena@yandex.ru; Rzaev, R. M., E-mail: abdinov-axmed@yandex.ru [Azerbaijan State Economic University (Azerbaijan); Ragimova, N. A.; Amirova, S. I. [Baku State University (Azerbaijan)

    2016-01-15

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

  7. LiDy(PO34

    Directory of Open Access Journals (Sweden)

    Fathia Chehimi-Moumen

    2008-07-01

    Full Text Available Single crystals of lithium dysprosium polyphosphate, LiDy(PO34, were prepared by the flux method. The atomic arrangement is built up by infinite (PO3n chains extending along the b axis. Dy3+ and Li+ cations alternate in the middle of four such chains, with Dy...Li distances of 3.54 (1 and 3.48 (1 Å. The DyO8 dodecahedra and LiO4 tetrahedra deviate significantly from the ideal geometry. Both Dy and Li occupy special positions (Wyckoff position 4e, site symmetry 2.

  8. Luminescence behavior of Dy 3+ ions in lead borate glasses

    Science.gov (United States)

    Pisarska, Joanna

    2009-10-01

    Dy-doped lead borate glasses were studied. The luminescence spectra showed two characteristic bands at 480 and 573 nm due to 4F 9/2- 6H 15/2 (blue) and 4F 9/2- 6H 13/2 (yellow) transitions of Dy 3+. The yellow/blue luminescence of trivalent dysprosium was analyzed as a function of the B 2O 3/PbO ratios, the activator (Dy 3+) and the PbX 2 (X = F, Cl, Br) content.

  9. SPECTROSCOPIC PROPERTIES OF THE Ln-Ge COMPLEXES WITH DIETHYLENETRIAMINEPENTAACETIC ACID

    Directory of Open Access Journals (Sweden)

    Sergiy Smola

    2007-06-01

    Full Text Available Four new heteronuclear lanthanide complexes with general formula [Ge(OH(μ-HDTPALnGe(OH (μ-DTPA] (Ln = Sm – Dy were synthesized and subsequently characterized by different physico- chemical methods. The structures of new compounds have been proposed. In considered complexes the 4f-luminescence of three-charged ions of samarium, europium, terbium and dysprosium is realized at UV-excitation. It is noteworthy that it is the first observation of 4f-luminescence in water solutions of heteronuclear f-p-complexes. The comparison of luminescent characteristics of hetero- and homonuclear landthanide complexes is described and discussed as well.

  10. Mesoporous tertiary oxides via a novel amphiphilic approach

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, Natasha; Hall, Simon R., E-mail: simon.hall@bristol.ac.uk, E-mail: Annela.Seddon@bristol.ac.uk [Bristol Centre for Functional Nanomaterials, Centre for Nanoscience and Quantum Information, Tyndall Avenue, Bristol BS8 1FD, United Kingdom and Complex Functional Materials Group, School of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom); Seddon, Annela M., E-mail: simon.hall@bristol.ac.uk, E-mail: Annela.Seddon@bristol.ac.uk; Hallett, James E. [H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Kockelmann, Winfried [STFC Rutherford Appleton Laboratory, Chilton OX11 0QX (United Kingdom); Ting, Valeska P. [Department of Chemical Engineering, University of Bath, Bath BA2 7AY (United Kingdom); Sadasivan, Sajanikumari; Tooze, Robert P. [Sasol Technology (UK) Ltd, Purdie Building, North Haugh, St Andrews, Fife KY16 9ST (United Kingdom)

    2016-01-01

    We report a facile biomimetic sol-gel synthesis using the sponge phase formed by the lipid monoolein as a structure-directing template, resulting in high phase purity, mesoporous dysprosium- and gadolinium titanates. The stability of monoolein in a 1,4-butanediol and water mixture complements the use of a simple sol-gel metal oxide synthesis route. By judicious control of the lipid/solvent concentration, the sponge phase of monoolein can be directly realised in the pyrochlore material, leading to a porous metal oxide network with an average pore diameter of 10 nm.

  11. Exploring Rare Earths supply constraints for the emerging clean energy technologies and the role of recycling

    DEFF Research Database (Denmark)

    Habib, Komal; Wenzel, Henrik

    The dependency on critical resources like Rare Earth Elements (REEs) has been pronounced as a potential barrier to a broader implementation of emerging renewable energy technologies. This study explores the dependency of such technologies especially wind turbines and electric vehicles along...... with other background end-uses on two key REEs, i.e. neodymium (Nd) and dysprosium (Dy). Our study reveals that a highly accelerated rate of REEs mining is unavoidable in order to keep up with the pace of increasing demand from new technologies required in a renewable energy strategy for meeting the climate...

  12. Persistent nonequilibrium dynamics of the thermal energies in the spin and phonon systems of an antiferromagnet

    Directory of Open Access Journals (Sweden)

    A. von Reppert

    2016-09-01

    Full Text Available We present a temperature and fluence dependent Ultrafast X-Ray Diffraction study of a laser-heated antiferromagnetic dysprosium thin film. The loss of antiferromagnetic order is evidenced by a pronounced lattice contraction. We devise a method to determine the energy flow between the phonon and spin system from calibrated Bragg peak positions in thermal equilibrium. Reestablishing the magnetic order is much slower than the cooling of the lattice, especially around the Néel temperature. Despite the pronounced magnetostriction, the transfer of energy from the spin system to the phonons in Dy is slow after the spin-order is lost.

  13. DFT investigations of hydrogen storage materials

    Science.gov (United States)

    Wang, Gang

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

  14. Effect of heat treatment on microstructure and mechanical properties of high boron white cast iron

    Energy Technology Data Exchange (ETDEWEB)

    Chen Xiang, E-mail: xchen@mail.tsinghua.edu.cn [Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Li Yanxiang [Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China)

    2010-12-15

    Research highlights: {yields} The iron comprises a fine pearlite and M{sub 2}B boride at as-cast condition. {yields} Tempered at a higher temperature, some particles precipitated in the matrix. {yields} The secondary precipitates have a crystal structure of M{sub 23}(B,C){sub 6}. {yields} Optimum structure is obtained when tempered at 400 deg. C. - Abstract: The effect of different tempering temperatures on the microstructure and mechanical properties of high boron white cast iron after air quenching was studied. The experimental results indicate that the high boron white cast iron comprises a dendritic matrix and interdendritic boride M{sub 2}B that distributed in the form of continuous network and the matrix is composed of fine pearlite at as-cast condition. After austenitising at 920 deg. C and air quenching, the matrix of high boron cast iron is changed from pearlite to lath-type martensite, and the morphology of boride is still kept in the form of continuous network. After tempered at 200 deg. C or a higher temperature, a secondary precipitation with a size of tens of nanometers is found in the matrix, and the size and the amount of this secondary precipitation increase with the increasing of tempering temperature. TEM analysis shows that the secondary precipitates have a crystal structure of M{sub 23}(B,C){sub 6}. With the increasing of tempering temperature after air quenching, the hardness decreases, and the impact toughness firstly increases to a maximum value and then decreases. The optimum structure that has a combination of high hardness and high impact toughness can be obtained when the tempering temperature is lower than 400 deg. C.

  15. TO DETERMINATION OF INFLUENCE FOR VARIATIONS IN LASER TREATMENT MODES ON TRIBOLOGICAL CHARACTERISTICS OF CUTTING TOOL

    Directory of Open Access Journals (Sweden)

    O. V. Diachenko

    2016-01-01

    Full Text Available The paper considers problems pertaining to higher durability and reliability of a cutting tool for cutting gastronomic products while using laser processing that leads to resistance increase of material operating surfaces against impact forces. Influence of laser fusion with additional doping on structure, microhardness, wear resistance for adhesive coatings of Fe–B–Cr–Si system has been studied in the paper. In order to solve a problem for selection of optimal qualitative and subsequently quantitative composition of a multi-component coating a mathematical modeling method using Scheffe’s simplex lattices has been used in the paper. Similar tendency for measuring micro-structure of all adhesive coatings fused by laser beams has been established in the paper. Increase in beam speed has caused the following microstructure changes: cast equilibrium, dendrite, supersaturated boride, carbide and boride. Response surface models have been found and they provide the possibility to assess influence quantity of laser processing parameters on microhardness of adhesive coatings obtained by laser doping and intensity of their wear under various conditions for all investigated compositions.It has been ascertained that there is no strict correlation between hardness and intensity of coating wear after laser doping used for adhesive coatings. This testifies to the fact that hardening has taken place not only due to an increase of carbide-boride phase, but also due to matrix hardening.In addition, a regression model for coating composition effect on tribological characteristics of the adhesive coatings has revealed that an optimal composition of a multicomponent coating ensuring maximum wear resistance of coatings constitutes B4C is 2/3 and 1/3 TaB. It has been determined that hardening of the adhesive coating after laser doping while using multicomponent coating occurs not only due to increase of carbide-boridnoy phase, but also due to matrix hardening.

  16. Characterization of Fe-Cr-B based coatings produced by HVOF and PTA processes

    Science.gov (United States)

    Kim, Hyung-Jun; Grossi, Stephanie; Kweon, Young-Gak

    1999-02-01

    Two Fe-Cr-B based gas atomized powders, Armacor M and 16, were thermally sprayed on a low carbon steel substrate, using the HVOF (High Velocity Oxygen Fuel) process. Armacor M was also weld-surfaced with the PTA (Plasma Transferred Arc) process. The resultant deposits were subsequently characterized, using X-ray diffraction, scanning electron microscopy, and microhardness measurement. The effects of heat treatment were also studied for HVOF-sprayed coatings. The wear performance of the coatings was investigated by two-body abrasive wear tests. The results of microstructural analysis of as-sprayed deposits revealed oxide and boride phases such as Fe3O4 and Cr1.65F0.35B0.96 in an α matrix for the HVOF-sprayed Armacor 16 coating, and only the boride phases (Cr1.65F0.35B0.96 and Cr2B) in an α matrix for the HVOFsprayed Armacor M coating. PTA weld-surfaced Armacor M coating contains needle-type long precipitates of Cr2B) and Cr1.65F0.35B0.96, in the α matrix. The hardness of the HVOF-sprayed Armacor 16 coating after heat treatment was substantially less than that of the as-sprayed coating due to the phase transformation from α to γ phase. Heat treatments of the HVOF-sprayed Armacor M coating did not produce changes in phase and its hardness decreased as compared to that of the as-sprayed coating. While HVOF-sprayed and PTA weld-surfaced Armacor M coatings have the same hardness, the latter shows better abrasive wear resistance because of the size and orientation of its boride phases. The broadening of the XRD patterns and the increase in hardness after wear testing suggest that the transformation from the crystalline to the amorphous structure occurred on the uppermost layer during wear testing.

  17. Promotion of the Growth of Boron-Carbide Nanowires

    Science.gov (United States)

    Kranov, Yanko; Zhang, Daqing; McIlroy, David; Norton, Grant

    2000-03-01

    Boron carbide, is a wide bandgap semiconductor (2.1eV) with a high melting temperature in excess of 2400^circC. Initial studies indicate that nanowires of boron carbide approximately 25 ~30 μm in length and less than 100 nm in diameter can be grown by the technique of plasma enhanced chemical vapor deposition by a mode of the vapor-liquid-solid mechanism [1] at relatively low temperatures ( ~1150^circC). Through the use of boron based eutectics such as FeB, NiB and PtB nanowire growth at temperatures below 1150^circC. These metal borides have successively lower melting temperatures, respectively. In this paper we will discuss a simple technique for making submicron metal boride particles, as well as a simple means of depositing them onto a surface. In addition, the effect of droplet size on nanowire diameter and the stability of the size of the metal boride droplet during growth will be discussed. These studies demonstrate that the surface can be selectively seeded thereby controlling the location of the nanowires, i.e. select area deposition. Lastly, the techniques and materials used to grow boron carbide nanowires can easily be used to grow other types of nanowires, as well as carbon nanotubes. [1]. D. N. McIlroy, Daqing Zhang, Robert M. Cohen, J. Wharton, Yongjun Geng, M. Grant Norton, G. De Stasio, B.Gilbert, L.Perfetti, J.H.Streiff, B.Broocks and J.L. McHale, Phys. Rev. B 60 (1999) 4874

  18. 电抗器

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A proof-of-concept study of the use of complex borides for disassembly of decommissioned nuclear reactor containment vessels,A reactor system combining reductive dechlorin ationwith co-metabolic oxidation for complete degradation, of tetrachloroethylene,A Reduced-Basis Discretization Method for Chemical Vapor Deposition Reactor Simulation,A strategy for supervisory control of batch reactors: an experimental study, A STUDY OF BENZENE FORMATION IN A LAMINAR FLOW REACTOR,A theoretical model Of critical heat flux in flow boiling at low qualities。

  19. A Comprehensive Review of Modeling of Impact Damage in Ceramics

    Science.gov (United States)

    1988-12-01

    6272. 5. Wilkins, M.L., in BORON AND FRACTORY BORIDES, edited by V.I. Matkovis, The Carborundum Comp., ( 1977 ), pp. 633-648. 6. McQueen, R.G., Marsh...2530. 14. Grady, D.E., in ’High Pressure Research, Applications in Geophysics,’ edited by M.H. Manghnani, S. Akimoto, Acad. Press, ( 1977 ), pp. 389-438...Proceedings Cement Based ComDosites: Strain Rate Effects on Fracture, ed. by S. Mindess and S.P. Shah, Vol. 64, (1986), pp. 119-138. 84 27. Jawed, I

  20. Redetermination of the perovskite-type compound YRh3B revealing a Rh deficiency

    Directory of Open Access Journals (Sweden)

    Humihiko Takei

    2008-10-01

    Full Text Available In contrast with previous structural studies of ytterbium trirhodium boride, YbRh3B, that suggest a boron deficiency, the current redetermination of the crystal structure of YbRh3B revealed instead a rhodium deficiency with a refined composition of YbRh2.67 (2B. In the ABX3 perovskite-type structure, Yb, B and Rh are located on the A, B and X positions, respectively, with site symmetries of moverline{3}m for the A and B sites, and 4/mm.m for the X site.

  1. High-Temperature Ceramic Matrix Composite with High Corrosion Resistance

    Science.gov (United States)

    2010-06-02

    size after load increase. Fig. 2.12. Coefficients α, β and γ of TiN–AlN ceramics (a) and of hard alloys (b) in dependence on relative crack length...P286 – FINAL REPORT PAGE 12 02-Jun-10 1. Introduction Ceramic borides, such as hafnium diboride (HfB2) and zirconium diboride (ZrB2...of α, β and γ, carried out for technically important ceramics and hard alloys , showed that the increase of relative crack length c/a corresponds to a

  2. Effect of Heat Treatment on High Temperature Stress Rupture Strength of Brazing Seam for Nickel-base Superalloy

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In order to enhance the high-temperature stress rupture strength of brazing seam by heat treatment, it was diffusion treated, then solution heat treated, and finally aging treated. The microstructure of brazing seam especially morphology of phase and boride was observed and the strength of brazing seam was measured in this process. The results show that heat treatment can enhance high-temperature stress rupture strength by improving the microstructure of brazing seam. The strength of brazing seam after solution heat treatment decreases in comparison with that only after diffusion treatment while aging treatment after solution heat treatment increases the strength of brazing seam.

  3. Interface reaction between nickel-base self-fluxing alloy coating and steel substrate

    Science.gov (United States)

    Otsubo, F.; Era, H.; Kishitake, K.

    2000-06-01

    The interface reaction between a nickel-base, self-fluxing alloy coating and a steel substrate has been investigated to examine the formation of “pores,” which are observed along the interface of used boiler tubes. It was found that lumpy precipitates form along the interface instead of pores after heating at high temperatures and that the precipitates are of Fe2B boride. The adhesion strength of the coating is not decreased by the formation of Fe2B precipitates along the interface because of the increase of the adhesion due to interdiffusion.

  4. Gas solid techniques for preparation of pure lanthanum hexaboride

    Institute of Scientific and Technical Information of China (English)

    Mukherjee; A.; Gulnar; A.K.; Sahoo; D.K.; Krishnamurthy; N.

    2012-01-01

    The processes reported for the preparation of lanthanum hexaboride (LaB6) from lanthanum oxide involve the use of carbon either elemental or in the form of boron carbide or elemental boron itself as reducing agents, fused salts at high temperatures or reactions which require the product boride to be leached out. Each of these techniques either increases the process costs and/or increases chances of contamination in fi-nal product. Pure LaB6 can best be prepared by a reaction which produces a gaseous byprodu...

  5. Containerless processing of amorphous ceramics

    Science.gov (United States)

    Weber, J. K. Richard; Krishnan, Shankar; Schiffman, Robert A.; Nordine, Paul C.

    1990-01-01

    The absence of gravity allows containerless processing of materials which could not otherwise be processed. High melting point, hard materials such as borides, nitrides, and refractory metals are usually brittle in their crystalline form. The absence of dislocations in amorphous materials frequently endows them with flexibility and toughness. Systematic studies of the properties of many amorphous materials have not been carried out. The requirements for their production is that they can be processed in a controlled way without container interaction. Containerless processing in microgravity could permit the control necessary to produce amorphous forms of hard materials.

  6. 镀铬

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    [篇名]Electrodeposition of hard, functional chromium from a trivalent bath, to replace hoxavalent chromium plating, [篇名 ] Energy conservation in hard chromium plating, [篇名] Highly Dispersed Green Silicate and Oxide Pigments Precipitated from Model Systems of Postgalvanic Waste, [ 篇名 ] RECOVERY OF CHROMIUM(Ⅵ) FROM ELECTROPLATING RINSE WATER: THE DEVELOPMENT OF A HOLLOW FIBRE SOLVENT EXTRACTION PROCESS, [ 篇名 ] Replacing solid electrolytic chromium by composite boride coatings based on Ni and Fe, [ 篇名 ] System of optimal control of galvanic process of chromium plating, [篇名] The characteristics of fin-nickel alloy films produced from stacked single layers by heat treatment.

  7. Development of Magnesium-Insertion Positive Electrode for Rechargeable Magnesium Batteries

    Institute of Scientific and Technical Information of China (English)

    Huatang YUAN; Lifang JIAO; Jiansheng CAO; Xiusheng LIU; Ming ZHAO; Yongmei WANG

    2004-01-01

    Magnesium-based rechargeable batteries might be an interesting future alternative to lithium-based batteries. It is so far well known that Mg2+ ion insertion into ion-transfer hosts proceeds slowly compared with Li+, so it is necessary to realize fast Mg2+ transport in the host in addition to other requirements as practical cathode materials for magnesium batteries. Positive electrode materials based on inorganic transition-metal oxides, sulfides, and borides are the only ones used up to now to insert magnesium ions. In this paper, the available results of research on materials suitable as possible, for secondary magnesium batteries, are reviewed.

  8. 碳氮共渗

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    [篇名 ] A study on friction and wear behaviour of carburized, carbonitrided and borided AISI 1020 and 5115 steels, [篇名 ] Alloy Carburization at Temperatures of 1,200 - 2,100 F(650-1,150 ℃), [篇名] Amorphous silicon carbonitride fibers drawn from alkoxide modified ceraser, [ 篇名 ] Bearings with incrcased reliability, [篇名 ] Bright outlook for hard coatings, [ 篇名 ] Carbonitridc coating by low-temperature diffusion process, [ 篇名 ] Carbonitridc nanomaterials, thin films, and solids.

  9. Assessment of the State of the Art of Ultra High Temperature Ceramics

    Science.gov (United States)

    Johnson, Sylvia; Gasch, Matt; Stackpoole, Mairead

    2009-01-01

    Ultra High Temperature Ceramics (UHTCs) are a family of materials that includes the borides, carbides and nitrides of hafnium-, zirconium- and titanium-based systems. UHTCs are famous for possessing some of the highest melting points of known materials. In addition, they are very hard, have good wear resistance, mechanical strength, and relatively high thermal conductivities (compared to other ceramic materials). Because of these attributes, UHTCs are ideal for thermal protection systems, especially those that require chemical and structural stability at extremely high operating temperatures. UHTCs have the potential to revolutionize the aerospace industry by enabling the development of sharp hypersonic vehicles or atmospheric entry probes capable of the most extreme entry conditions.

  10. Field Emission Cold Cathode Devices Based on Eutectic Systems

    Science.gov (United States)

    1981-07-01

    suggested that the most promising candidates are the carbides and borides of tantalum, hafnium and niobium together with zirconium carbide. The choice of...in ternary La-B-X systems, some evidence is available6 5 ’ 6 6( , to suggest that LaB6 and aluminium form a eutectic equilibrium, thereby creating a...the composition of the fibres and matrix. Fibres Matrix Nickel, wt.% 27.9 70.1 Molybdenum, wt.% 65.7 20.8 Tantalim, wt.% 2.0 2.8 Aluminium , wt.% 4.5

  11. Temperature dependences of the upper critical field and the Ginzburg-Landau parameter of Li 2Pd 3B from magnetization measurements

    Science.gov (United States)

    Landau, I. L.; Khasanov, R.; Togano, K.; Keller, H.

    2007-01-01

    We present temperature dependences of the upper critical magnetic field Hc2 and the Ginzburg-Landau parameter κ for a ternary boride superconductor Li2Pd3B obtained from magnetization measurements. A specially developed scaling approach was used for the data analysis. The resulting Hc2(T) curve turns out to be surprisingly close to predictions of the BCS theory. The magnetic field penetration depth λ, evaluated in this work, is in excellent agreement with recent muon-spin-rotation experiments. We consider this agreement as an important proof of the validity of our approach.

  12. Thermodynamic analysis of chemical compatibility of ceramic reinforcement materials with niobium aluminides

    Science.gov (United States)

    Misra, Ajay K.

    1990-01-01

    Chemical compatibility of several reinforcement materials with three niobium aluminides, Nb3Al, Nb2Al, and NbAl3, were examined from thermodynamic considerations. The reinforcement materials considered in this study include carbides, borides, nitrides, oxides, silicides, and Engel-Brewer compounds. Thermodynamics of the Nb-Al system were reviewed and activities of Nb and Al were derived at desired calculation temperatures. Criteria for chemical compatibility between the reinforcement material and Nb-Al compounds have been defined and several chemically compatible reinforcement materials have been identified.

  13. Thermodynamic analysis of chemical compatibility of several compounds with Fe-Cr-Al alloys

    Science.gov (United States)

    Misra, Ajay K.

    1993-01-01

    Chemical compatibility between Fe-19.8Cr-4.8Al (weight percent), which is the base composition for the commercial superalloy MA956, and several carbides, borides, nitrides, oxides, and silicides was analyzed from thermodynamic considerations. The effect of addition of minor alloying elements, such as Ti, Y, and Y2O3, to the Fe-Cr-Al alloy on chemical compatibility between the alloy and various compounds was also analyzed. Several chemically compatible compounds that can be potential reinforcement materials and/or interface coating materials for Fe-Cr-Al based composites were identified.

  14. Thermodynamic analysis of chemical compatibility of several reinforcement materials with niobium aluminides

    Science.gov (United States)

    Misra, Ajay K.

    1989-01-01

    Chemical compatibility of several reinforcement materials with three niobium aluminides, Nb3Al, Nb2Al, and NbAl3, were examined from thermodynamic considerations. The reinforcement materials considered in this study include carbides, borides, nitrides, oxides, silicides, and Engel-Brewer compounds. Thermodynamics of the Nb-Al system were reviewed and activities of Nb and Al were derived at desired calculation temperatures. Criteria for chemical compatibility between the reinforcement material and Nb-Al compounds have been defined and several chemically compatible reinforcement materials have been identified.

  15. Materials for high-temperature hydrogen fluorine environments. Final report, June 1976-December 1978

    Energy Technology Data Exchange (ETDEWEB)

    Holcombe, C.E. Jr.; Kovach, L.

    1981-03-01

    A determination has been made of the stability of 35 materials under high-temperature, fluorine rich, hydrogen fluoride torch testing. Refractory materials tested included 4 borides, 3 carbides, 3 nitrides, 12 oxides, 1 oxynitride, 1 sulfide, 10 metals, and carbon (10 types). Three materials distinctly performed better than nickel: lanthanum hexaboride, calcium hexaboride, and lanthanum silicon oxynitride. Of these, lanthanum hexaboride is the best candidate tested since it has an estimated upper use temperature > 1726 K, which is above the melting point and more than 300 K above the upper use temperature of nickel.

  16. Incoherent x-ray emission of titanium diboride at the boron site

    Energy Technology Data Exchange (ETDEWEB)

    Ederer, D.L.; Winarski, R.; Ek, J. van [Tulane Univ., New Orleans, LA (United States)] [and others

    1997-04-01

    This group has made a study of a large number of transition metal diborides and hexaborides. As an example they would like to consider one of them. This class of compounds are of technical interest because they are quite hard, metallic, and chemically stable, and have high melting points. In addition to the technical importance of the borides, the group is interested in compounds of this type because of the very strong 1s {r_arrow} p* resonance that has been observed and associated with the boron atom.

  17. The grain refinement of 6063 aluminum using Al-5Ti-1B and Al-3Ti-0.15C grain refiners

    Science.gov (United States)

    Moldovan, P.; Popescu, Gabriela

    2004-11-01

    The Al-Ti-B grain refiners containing boride nucleant particles are used to promote a uniform microstructure throughout aluminum ingots and to suppress the growth of columnar grains. In addition, for the last eight years a new generation of Al-Ti-C grain refiners has been used commercially in a wide range of alloy systems. This paper will compare the potency of the commercially available Al-5Ti-1B grain refiner with that of the Al-3Ti-0.15C grain refiner for the 6063 cast alloy.

  18. Creep and Oxidation of Hafnium Diboride Based Ultra High Temperature Ceramics at 1500C

    Science.gov (United States)

    2015-12-01

    Poisson’s Ratio 0.12 [52] Young’s Modulus 480 GPa [53] Bulk Modulus 212 GPa [9] Hardness 28 GPa [49] Fracture Toughness 4.0 MPa√m [36] Brittle to...additions of tungsten boride (WB) and tungsten carbide (WC) improved sintering and reduced the grain size of a HfB2 material system with 15% SiC by...oxygen impurities, improve densification, and limit grain growth, thus greatly improving flexural strength. Fracture toughness also improved

  19. Photothermal Mirror Method for the Study of Thermal Diffusivity and Thermo-Elastic Properties of Opaque Solid Materials

    Science.gov (United States)

    Marcano, Aristides; Gwanmesia, Gabriel; Workie, Bizenuh

    2017-09-01

    We have carried out the theoretical and experimental time evolution and amplitude study of the photothermal mirror signal generated by focusing a laser beam on the surface of a suite of solid samples. Based on a theoretical model that resolves the thermal diffusivity equation and the equation for thermo-elastic deformations simultaneously, we have calculated the transient time evolution and amplitude of the signal. We observe the same time evolution pattern for samples as diverse as glass, quartz, metals, and synthetic ceramic oxides. The data have yielded a linear dependence between the time build-up of the thermal mirror and the inverse of the thermal diffusivity for all the samples. For moderate power levels, we also observe a linear behavior between the stationary value of the signal and the thermally induced phase shift value. From the calibration curves, we have determined the thermally induced phase and the thermal diffusivity coefficients of two prospective nuclear reactor control rod materials, dysprosium titanate (Dy2TiO5) and dysprosium dititanate (Dy2Ti2O7) to be D = (7.0 ± 0.4) × 10^{-7} m^{2\\cdot s^{-1}}.

  20. Recycling as a strategy against rare earth element criticality: a systemic evaluation of the potential yield of NdFeB magnet recycling.

    Science.gov (United States)

    Rademaker, Jelle H; Kleijn, René; Yang, Yongxiang

    2013-09-17

    End-of-life recycling is promoted by OECD countries as a promising strategy in the current global supply crisis surrounding rare earth elements (REEs) so that dependence on China, the dominant supplier, can be decreased. So far the feasibility and potential yield of REE recycling has not been systematically evaluated. This paper estimates the annual waste flows of neodymium and dysprosium from permanent magnets, the main deployment of these critical REEs, during the 2011-2030 period. The estimates focus on three key permanent magnet waste flows: wind turbines, hybrid and electric vehicles, and hard disk drives (HDDs) in personal computers (PCs). This is a good indication of the end-of-life recycling of neodymium and dysprosium maximum potential yield. Results show that for some time to come, waste flows from permanent magnets will remain small relative to the rapidly growing global REE demand. Policymakers therefore need to be aware that during the next decade recycling is unlikely to substantially contribute to global REE supply security. In the long term, waste flows will increase sharply and will meet a substantial part of the total demand for these metals. Future REE recycling efforts should, therefore, focus on the development of recycling technology and infrastructure.