The Experts below are selected from a list of 1683 Experts worldwide ranked by ideXlab platform
H Amitsuka - One of the best experts on this subject based on the ideXlab platform.
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anomalous fermi liquid behavior of the dilute Uranium Alloys la1 xuxru2si2 x 0 07
Journal of the Physical Society of Japan, 2002Co-Authors: M Yokoyama, H Amitsuka, K Kuwahara, K Tenya, T SakakibaraAbstract:Low temperature properties of the dilute Uranium Alloys La 1- x U x Ru 2 Si 2 ( x ≤0.07) have been investigated by means of magnetic susceptibility χ, magnetization m , specific heat C P and electrical resistivity ρ measurements to clarify the single-U-site effects of URu 2 Si 2 . Local 5f electrons show a strong magnetic anisotropy along the tetragonal c axis, as is observed in other dilute Alloys Th 1- x U x Ru 2 Si 2 and Y 1- x U x Ru 2 Si 2 . As temperature is lowered below ∼60 K, the c -axis susceptibility χ c follows a ln T function, and ρ decreases in proportion to χ c . The 5f electronic specific heat C P 5f / T exhibits a broad peak at ∼10 K. The entropy change associated with this anomaly below 30 K is estimated to be only about 0.3 R ln 2. Although the local Fermi liquid behavior is observed in χ, C P and ρ at very low temperatures, the ln T decrease in ρ and the small entropy change provide a remarkable contrast with those expected in the usual magnetic dilute Alloys.
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unusual low temperature behavior of the dilute Uranium Alloys la1 xuxru2si2 x 0 07
Physica B-condensed Matter, 2000Co-Authors: M Yokoyama, H Amitsuka, K Kuwahara, K Tenya, A Okumura, T SakakibaraAbstract:Abstract We have investigated single-U-site properties of the dilute U Alloys La1−xUxRu2Si2 for x⩽0.07. Contrary to usual Kondo effect, electrical resistivity due to U ions shows a ln T decrease as temperature decreases. The 5f specific heat CP5f/T exhibits a broad peak at ∼ 10 K, and entropy change associated with this anomaly below 30 K is estimated to be only about 0.3 R ln 2 . These properties differ greatly from those seen in the usual dilute magnetic Alloys.
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anomalous transport properties of dilute Uranium Alloys r1 xuxru2si2 r th y x 0 07
Physica B-condensed Matter, 1999Co-Authors: H Amitsuka, K Kuwahara, K Tenya, T Sakakibara, M. Mihálik, T Yoshida, A A MenovskyAbstract:Abstract We investigate contribution of a single U ion to the electrical resistivity (Δρ) in the dilute U Alloys R 1−x U x Ru 2 Si 2 ( R = Th,Y ) for x⩽0.07. Contrary to the conventional Kondo behavior, in both systems Δρ exhibits an unusual decrease with reducing temperature below a characteristic temperature (T ∗ ) of ∼10 K ( R = Th ) and 40 K (Y). At higher temperatures, Δρ is almost independent of T with the amplitude (ΔρRT) of ∼ 59 (95) μΩ cm / U for R = Th (Y) . The dependence Δ ρ∼ ln T below T ∗ and the relationship Δ ρ(T→0)∼ 1 2 Δ ρ RT are found similarly between these two dilutions irrespective of T ∗ and ΔρRT, suggesting that these are universal features in the dilute limit of URu2Si2. The ln T decrease in Δρ is approximately proportional to the increase in the magnetic susceptibility, which provides a remarkable distinction between the present systems and known reverse-Kondo Alloys.
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single Uranium site properties of dilute Uranium Alloys uxth1 xpd2si2 x 0 07
Physica B-condensed Matter, 1995Co-Authors: H Amitsuka, T Shimamoto, Toshihisa Honma, T SakakibaraAbstract:Abstract Magnetic susceptibility X, specific heat C, and electrical resistivity ϱ have been investigated for dilute Uranium Alloys UxTh1−xPd2Si2 (x ⩽ 0.07), in the temperature range down to 100 mK. With decreasing x, unusual —In T behavior appears in X and C/T below about 6 K. A minimum resistance is observed at around 20 indicating the presence of Kondo scattering, while a non-trivial maximum is also found at around 3.5 K.
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anomalous low temperature properties of the dilute Uranium Alloys uxth1 xpt2si2 x 0 07
Journal of Magnetism and Magnetic Materials, 1995Co-Authors: H Amitsuka, T Sakakibara, T Hidano, Takashi Suzuki, T Akazawa, Toshizo FujitaAbstract:Abstract Low-temperature transport, thermal, and magnetic measurements on the dilute Uranium Alloys U 1− x Th x Pt 2 Si 2 ( x ≤ 0.07) reveal the non-Fermi liquid behavior suggesting the presence of the unconventional interplay between 5f electrons and conduction electrons. The divergence of the single-site paramagnetic susceptibility as T → 0 indicates a magnetically degenerate ground state of the 5f electrons.
C Suzuki - One of the best experts on this subject based on the ideXlab platform.
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relativistic density functional study of the solid solubility of transition metal γ Uranium Alloys the role of d d orbital interactions
Journal of Alloys and Compounds, 2011Co-Authors: Masayoshi Kurihara, Masaru Hirata, Jun Onoe, C SuzukiAbstract:Abstract The alloying behavior of transition metals (TMs) in solid γ-phase Uranium (γ-U), which is expected to be used as fuel for next-generation nuclear reactors, was investigated using the discrete–variational Dirac–Fock–Slater molecular orbital method. Using a model cluster, U 8 /TM, as the minimum unit of γ-U/TM Alloys, we evaluated the d-orbital energy of the TM (Md), the bond order between the TM and U atoms, and the orbital overlap population (OOP) between the atomic orbitals of the TM and U atoms. We subsequently examined the effect of these quantities on the maximum solid solubility (MSS) of the γ-U/TM Alloys. The interaction between the U-6d and TM-d atomic orbitals was found to play a key role in determining the MSS of the γ-U/TM Alloys. The magnitude of the MSS can be explained in terms of the stabilization energy, which is affected by the Md and the OOP, formed by d–d orbital interactions. We also mapped the MSS of γ-U/TM Alloys using the Md and the OOP as the alloying parameters. These results will assist the quantum design of nuclear fuel materials.
T Sakakibara - One of the best experts on this subject based on the ideXlab platform.
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anomalous fermi liquid behavior of the dilute Uranium Alloys la1 xuxru2si2 x 0 07
Journal of the Physical Society of Japan, 2002Co-Authors: M Yokoyama, H Amitsuka, K Kuwahara, K Tenya, T SakakibaraAbstract:Low temperature properties of the dilute Uranium Alloys La 1- x U x Ru 2 Si 2 ( x ≤0.07) have been investigated by means of magnetic susceptibility χ, magnetization m , specific heat C P and electrical resistivity ρ measurements to clarify the single-U-site effects of URu 2 Si 2 . Local 5f electrons show a strong magnetic anisotropy along the tetragonal c axis, as is observed in other dilute Alloys Th 1- x U x Ru 2 Si 2 and Y 1- x U x Ru 2 Si 2 . As temperature is lowered below ∼60 K, the c -axis susceptibility χ c follows a ln T function, and ρ decreases in proportion to χ c . The 5f electronic specific heat C P 5f / T exhibits a broad peak at ∼10 K. The entropy change associated with this anomaly below 30 K is estimated to be only about 0.3 R ln 2. Although the local Fermi liquid behavior is observed in χ, C P and ρ at very low temperatures, the ln T decrease in ρ and the small entropy change provide a remarkable contrast with those expected in the usual magnetic dilute Alloys.
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single Uranium site properties of dilute Uranium Alloys uxth1 xpd2si2 x 0 07
Physica B-condensed Matter, 1995Co-Authors: H Amitsuka, T Shimamoto, Toshihisa Honma, T SakakibaraAbstract:Abstract Magnetic susceptibility X, specific heat C, and electrical resistivity ϱ have been investigated for dilute Uranium Alloys UxTh1−xPd2Si2 (x ⩽ 0.07), in the temperature range down to 100 mK. With decreasing x, unusual —In T behavior appears in X and C/T below about 6 K. A minimum resistance is observed at around 20 indicating the presence of Kondo scattering, while a non-trivial maximum is also found at around 3.5 K.
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anomalous low temperature properties of the dilute Uranium Alloys uxth1 xpt2si2 x 0 07
Journal of Magnetism and Magnetic Materials, 1995Co-Authors: H Amitsuka, T Sakakibara, T Hidano, Takashi Suzuki, T Akazawa, Toshizo FujitaAbstract:Abstract Low-temperature transport, thermal, and magnetic measurements on the dilute Uranium Alloys U 1− x Th x Pt 2 Si 2 ( x ≤ 0.07) reveal the non-Fermi liquid behavior suggesting the presence of the unconventional interplay between 5f electrons and conduction electrons. The divergence of the single-site paramagnetic susceptibility as T → 0 indicates a magnetically degenerate ground state of the 5f electrons.
Masayoshi Kurihara - One of the best experts on this subject based on the ideXlab platform.
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relativistic density functional study of the solid solubility of transition metal γ Uranium Alloys the role of d d orbital interactions
Journal of Alloys and Compounds, 2011Co-Authors: Masayoshi Kurihara, Masaru Hirata, Jun Onoe, C SuzukiAbstract:Abstract The alloying behavior of transition metals (TMs) in solid γ-phase Uranium (γ-U), which is expected to be used as fuel for next-generation nuclear reactors, was investigated using the discrete–variational Dirac–Fock–Slater molecular orbital method. Using a model cluster, U 8 /TM, as the minimum unit of γ-U/TM Alloys, we evaluated the d-orbital energy of the TM (Md), the bond order between the TM and U atoms, and the orbital overlap population (OOP) between the atomic orbitals of the TM and U atoms. We subsequently examined the effect of these quantities on the maximum solid solubility (MSS) of the γ-U/TM Alloys. The interaction between the U-6d and TM-d atomic orbitals was found to play a key role in determining the MSS of the γ-U/TM Alloys. The magnitude of the MSS can be explained in terms of the stabilization energy, which is affected by the Md and the OOP, formed by d–d orbital interactions. We also mapped the MSS of γ-U/TM Alloys using the Md and the OOP as the alloying parameters. These results will assist the quantum design of nuclear fuel materials.
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application of the relativistic dv xα molecular orbital method to γ Uranium Alloys with transition metals
Progress in Nuclear Energy, 2008Co-Authors: Masayoshi Kurihara, Masaru Hirata, Jun Onoe, Hirohide NakamatsuAbstract:Abstract The alloying behavior of 4d and 5d transition metals (TMs) in γ-phase solid Uranium (U) has been investigated using the discrete-variational Dirac–Fock–Slater (DV-DFS) method. We examined the d-orbital energy (Md value) of these TMs, the orbital overlap population (OOP) between the d-orbital of these TMs and the 5f or 6d orbital of γ-U, and the effective charge on each atom of the γ-U/TM alloy, and the effect of these parameters on alloying. It was found that the maximum solid solubility (MSS) of TMs into γ-U was exponentially proportional to both the Md and the OOP (U5f–TMd and U6d–TMd), except for Ta and W elements. We found a good correlation between the MSS and Md, the effective charge, or OOP.
G M Robinson - One of the best experts on this subject based on the ideXlab platform.
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machining of Uranium and Uranium Alloys with coated cutting tools
2013Co-Authors: Mark J Jackson, G M Robinson, Michael D Whitfield, Rodney Handy, Jonathan S MorrellAbstract:The machining of depleted Uranium and its Alloys is discussed in this chapter. Traditionally, these materials have been machined using uncoated cutting tools with limited success. New developments in titanium-based coatings such as cation-substituted Ti l−x−y−z Al x Cr y Y2N Alloys, with y = 0.03 and z = 0.02, have been shown to offer enhanced high-temperature oxidation resistance compared to presently used TiN and Ti l−x Al x N films that are deposited to cutting tool surfaces. Layers (3 μm thickness) deposited by unbalanced magnetron sputter deposition to small grain WC–Co cutting tool inserts which had been ion etched in situ using a steered Cr-metal-ion cathodic arc discharge at an Ar pressure of 6 × 10−4 mbar (0.45 mTorr) have been tested and found to be beneficial in terms of tool life. The metal-ion etching promoted initial local epitaxy on individual substrate grains, while the overall film texture evolved through competitive growth to (111) in Ti0.44Al0.53Cr0.03N Alloys and (200) in Ti0.43Al0.52Cr0.03Y0.02N Alloys. Although Ti0.04Al0.53Cr0.03N layers exhibited a columnar microstructure similar to that previously observed in Ti l−x Al x N Alloys, the addition of 2 mol% YN resulted in significant grain refinement giving rise to an equiaxed structure. The Knoop microhardness of Ti0.43Al0.52Cr0.03Y0.02N Alloys was HK0.025 = 2,700 kg mm−2 compared to 2,400 kg mm−2 for Ti0.44Al0.53Cr0.03N. Rapid oxidation of coatings, as determined from thermogravimetric measurements, ranged from ≈600 °C for TiN, 870 °C for Ti0.466Al0.54N, and 920 °C for Ti0.44Al0.53Cr0.03N to 950 °C for Ti0.43Al0.522Cr0.03Y0.02N. Machining experiments indicated that cutting tool life is improved significantly using yttrium-doped titanium-based coatings when machining Uranium Alloys.
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grinding of Uranium and Uranium Alloys
2013Co-Authors: Mark J Jackson, G M Robinson, Rodney Handy, Micheal D Whitfield, Jonathan S MorrellAbstract:The grinding of Uranium and its Alloys is not very well understood, and the existing information that relates grinding process parameters and grinding wheel structure to the grinding performance is outdated at best. Since the initial papers published on grinding Uranium were published more than 30 years ago, advances in grinding and the development of abrasive grains and bonding systems have accelerated to such an extent that the old published data is not very reliable. Therefore, this chapter explains the current advances in abrasive grain technology and also covers the recommendations made by previously generated data and how the data could be improved using the new types of grains and bonding systems.
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Machining of depleted Uranium using coated cutting tools
Journal of Materials Engineering and Performance, 2006Co-Authors: Mark J Jackson, G M RobinsonAbstract:The machining of depleted Uranium and its Alloys are discussed in this article. Traditionally, these materials have been machined, with limited success, using uncoated cutting tools. New developments in titanium-based coatings such as cation-substituted Ti_1- x-y-z Al_ x Cr_ y Y_2N Alloys, with y =0.03 and z =0.02, have been shown to offer enhanced high-temperature oxidation resistance compared with the presently used TiN and Ti_1- x Al_ x N films that are deposited to cutting tool surfaces. Layers (3 µm thickness) were deposited by unbalanced magnetron sputter (UBM) deposition to small-grain WC-Co unused cutting tools that had been ion-etched in situ using a steered Cr-metal-ion cathodic arc (CA) discharge at an Ar pressure of 6 × 10^−4 mbar (0.45 m Torr). The metal ion etching promoted initial local epitaxy on individual substrate grains while the overall film texture evolved through competitive growth to a (111) plane in Ti_0.44Al_0.53Cr_0.03N Alloys and (200) plane in Ti_0.43Al_0.52Cr_0.03Y_0.02N Alloys. Although Ti_0.04Al_0.53Cr_0.03N layers exhibited a columnar microstructure that was similar to that previously observed in Ti_1- x Al_ x N Alloys, the addition of 2 mol% YN resulted in significant grain refinement, giving rise to an equiaxed structure. The Knoop microhardness of Ti_0.43Al_0.52Cr_0.03Y_0.02N Alloys was HK_0.025=2700 kg/mm compared with 2400 kg/mm for Ti_0.44Al_0.53Cr_0.03N Alloys. The onset of rapid oxidation, as determined from thermogravimetric measurements, ranged from ≈600 °C for TiN; to 870 °C for Ti_0.466Al_0.54N; to 920 °C for Ti_0.44Al_0.53Cr_0.03N; to 950 °C for Ti_0.43Al_0.522Cr_0.03Y_0.02N. Machining experiments indicated that cutting tool life is improved significantly using Y-doped Ti-based coatings when machining Uranium Alloys.
