bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Low Dose Rate Radiation on the Microchemistry of 304 Stainless Steel
Authors: Allen T. R. , Cole J. I. , Kenik E. A. 
Published: April 2011

AbstractAs part of the shutdown of the EBR-II reactor, structural materials were retrieved to analyze the effect of long term, low dose rate irradiation. In this work, the effect of low dose rate (10 to 10−9 dpa/s) irradiation on grain boundary and void surface chemistry is analyzed. These dose rates are comparable to those in light water reactor structural components. The components were irradiated at 375-379°C, temperatures near the highest temperatures experienced in pressurized water reactors. Radiation-induced segregation (RIS) was measured on samples taken from 304 stainless steel hex ducts irradiated to doses between 10 and 12 dpa. Radiation-induced segregation is shown to vary with dose rate, with measured grain boundary chromium concentrations reaching as low as 5 at. % and nickel concentrations reaching as high as 33 at. %. For some radiation conditions, significant grain boundary precipitation occurs, possibly leaving components susceptible to environmental attack.
Redistribution of Alloying Elements in Electron-Irradiated Iron-Based Fcc Alloys Studied by Hydrogen-Probe Mechanical Spectroscopy
Authors: Smuk S. , Häninen H. , Jagodzinski Y. , Tarasenko O. 
Published: April 2011

AbstractEffect of electron irradiation on substitutional ordering was studied in Fe-36.7 wt.% Ni invartype alloy and Fe-25.2 wt.% Cr-20.2 wt.% Ni austenitic stainless steel. It was shown that the fine structure of the hydrogen Snoek-type peak in invar changes after irradiation to a fluence of 1019 e−.cm−2 with electrons with an energy of 3 MeV as compared to the solution treated condition. Irradiation affects the temperature behavior of the shear modulus of invar. No significant effect of irradiation on hydrogen Snoek-type peaks was detected in stainless steel.
Mixing and Demixing of Cu-Mo
Authors: Wei L. C. , Averback R. S. 
Published: April 2011

AbstractIon beam mixing of Cu/Mo multilayer samples and demixing of Cu-Mo alloy samples were examined as functions of temperature and ion mass. Even at liquid nitrogen temperature, the mixing of one component in other was very small under 1.0 MeV Kr irradiation. The maximum solubility was about 10%. Irradiation of homogeneous Cu-Mo alloys under the same conditions, moreover, led to phase separation. These conclusions were deduced from bulk X-ray diffraction measurements and corroborated by EXAFS examination. The maximum solubility obtained by irradiating multilayer samples occurred at about 600 K. At lower or higher temperature, the solubility of Cu in Mo-rich phase was lower. A model based on the ballistic difflusion explains these results.
Kinetic Lattice Monte Carlo Simulations of Cascade Aging in Iron and Dilute Iron-Copper Alloys
Authors: Wirth B. D. , Odette G. R. 
Published: April 2011

AbstractNeutron hardening and embrittlement of pressure vessel steels is due to a high density of nm scale features, including copper-manganese-nickel rich precipitates and what are generally believed to be defect cluster-solute complexes. It has been postulated that the sub nanometer defect cluster-solute complexes form directly in displacement cascades. Cluster-complexes that are thermally unstable mediate the effect of flux on embrittlement kinetics. Larger cluster-complexes, that are relatively thermally stable for irradiation times up to 1 Gs, cause embrittlement in low copper steels. Robust characterization of these two types of so-called matrix defects has been an elusive goal. In this work, Kinetic Lattice Monte Carlo (KLMC) simulations of the long term evolution of the vacancy-rich cascade core regions were carried out for both pure iron and dilute iron-copper alloys at the nominal irradiation temperature of 563°K up to times when the vacancy clusters completely dissolve. Energetics were based on lattice embedded atom method potentials. Special time scaling and pulse annealing techniques were used to deal with the enormous range of inherent time scales involved, viz., rapid free vacancy jumps to slow emission from large complexes. Three-dimensional clusters rapidly form, containing a wide range of vacancies, as well as copper atoms in alloys. Small complexes are very mobile and growth takes place primarily by coalescence. The vacancy clusters ultimately dissolve at times from less than 0.1 to more than 100 MS. These simulations support the hypotheses that cascade cluster- complexes constitute both thermally stable and unstable matrix defect features.
Defect Generation by Proton Irradiation of Semi-Insulating Lec GaAs
Authors: Castaldin A. , Cavallini A. , Polenta L. , Canali C. , Nava F. , Puentee E. De La , Alvarez A. , Jimenez J. 
Published: April 2011

AbstractHigh energy and high fluence proton irradiated semi-insulating GaAs has been studied by EBIC, PL mapping, C-V, NTSC, PICTS and p-DLTS. The main defects generated by the irradiation were analyzed. An EL2-like defect was found to be dominant. The generation of this defect annihilates the typical cellular distribution of EL2 in as-grown material. The generated EL2 defects present a different photoquenching behavior than the as-grown EL2 defects.
Amorphization Mechanism of Si/Ge Superlattices Upon Ion Implantation
Authors: Sobolev N.A. , Kaiser U. , Khodos I.I. , Presting H. , König U. 
Published: April 2011

AbstractThe damage production in the Si9Ge6 superlattices (SLs) upon implantation of 150 keV Ar+ ions at 300 K was studied my means of the cross-sectional transmission electron microscopy (XTEM) and electron microdiffraction. It was found that the amorphization occurs in a narrow dose range of (1 – 2) × 1014 cm-2 via accumulation of point defects. The conclusion drawn earlier (Mater. Sci. Forum 248-249, 289 (1997)) on the coherent amorphization of the Si and Ge layers in the SLs was confirmed. Possible mechanisms of the layer interaction leading to the observed behavior are discussed.
Characterization of the Electron Density in Si+-Implanted InP by Means of Raman Scattering by Lo-Plasma Coupled Modes
Authors: Ibáñez J. , Cuscó R. , Blánco N. , González-Díaz G. , Jiménez J. , Artús L. 
Published: April 2011

AbstractWe have studied by means of Raman spectroscopy the electron density in two different n-type InP samples with similar doping densities, obtained, respectively, by ion-beam implantation of 150 keV Si+ and by uniform Sn doping during LEC growth. The Raman spectra recorded at 80 K display in both cases the L+ and L– phonon-plasmon coupled modes. For the homogeneously doped InP:Sn sample, a simultaneous fit to the L+ and L– peaks of a line shape model based on the Lindhard-Mermin dielectric function yields accurate values of the charge density. In the implanted sample, the nonuniformity of the charge distribution substantially broadens the L+ modes, but the line shape fit to the L– mode still yields an average value of the electron density in the region probed by the laser beam.
Freeform Fabrication of Components with Designed Cellular Structure
Authors: Zimbeck W. R. , Rice R. W. 
Published: April 2011

AbstractOne of the more intriguing freeform fabrication application areas is the fabrication of bodies with designed microstmctures. While design of reinforced composite microstructures has received much attention, construction of designed porous or cellular structures may have greater technical feasibility and offers attractive practical benefits. Freeform fabrication advantages compared to existing foam and honeycomb fabrication techniques are discussed with emphasis on control over pore size, shape, orientation and distribution including hierarchical and functionally graded pore structures, all in combination with the ability to fabricate near net shape objects of complex geometry. Potential applications include the use of designed surface and bulk porosity to enhance both short and long term fixation of structural metal implants to bone, and lightweighting of aerospace components to approach optimized mass efficiency based on predicted stress distributions within a part. Progress using a stereo/photolithographic fabrication technique to construct designed pore structures in stainless steel bodies is presented. Various techniques used to fabricate fine porosity (size less than a layer thickness), coarse porosity (size greater than a layer thickness), and truss, open cell and honeycomb structures with characteristically high cell volume fraction (i.e., greater than 50 percent) are described.
Single Crystal Growth and Thermoelectric Properties of Ce5Cu19P12
Authors: Proctor K. J. , DiSalvo F. J. 
Published: April 2011

AbstractSingle crystals of the known ternary cerium intermetallic Ce5Cu19P12were grown by Sn flux and I2transport methods. The long axis of the black hexagonal needles was confirmed to be the c-axis by single crystal X-ray diffraction. Electrical resistivity of both single crystals and a pressed pellet was measured from 4 - 300 K; the room temperature resistivity is about 400 μΩ-cm for the needle axis of the crystals and about 5 mΩ-cm for the pressed pellet. The thermopower of the pressed pellet was found to be 34 μV/K at room temperature.
Substitutional Effects on the Thermoelectric Properties of Transition Metal Pentatellurides
Authors: Littleton R. T. , Kolis J. W. , Feger C. R. , Tritt Terry M. 
Published: April 2011

AbstractThe thermoelectric properties (resistivity and thermopower) of single crystals of the low-dimensional pentatelluride materials, Hffe5 and ZrTe5, have been measured as a function of temperature from 10K < T < 320K. Both parent materials exhibit a resistive transition peak, Tp ≈ 80K for HfTe5 and Tp ≈ 145K for ZrTe5. Each display a large positive (p-type) thermopower (α ≥ +125μV/K) around room temperature, which undergoes a change to a large negative (n-type) thermopower (α≤-125μV/K) below the peak temperature. The magnitude of this resistive anomaly is typically 3–7 times the room temperature value of ≈ 1 mΩ•cm. Through isoelectronic substitution of Zr for Hf (Hf1-xZrxTe5), a systematic shift is observed in Tp as the Zr concentration increases. Small Ti substitution for Hf and Zr affects the electronic properties strongly, producing a substantial reduction in Tp for either parent compound. However, the large values of thermopower and the magnitude of the resistive peak remain essentially unchanged. Substitutions of Se or Sb on the Te sites greatly affects the electronic behavior of the parent materials. Se doping increases the thermopower values by ≈20% while decreasing the resistivity by as much as 25%. These effects double the power factor, α2σT, of the parent materials. Small Sb substitutions appear to completely suppress the resistive anomaly. These features in the resistivity and thermopower signal a large degree of tunability in the temperature range of operation. The potential of these materials as candidates for low temperature thermoelectric applications will be discussed.
Semiconductor Clathrates: A pgec System with Potential for Thermoelectric Applications
Authors: Nolas G. S. 
Published: April 2011

AbstractAn investigation into the structural, chemical, electronic, and thermal properties of polycrystalline semiconductor clathrate compounds with different “guest” ions in the voids of these structures is presently underway by the author and his colleges. Despite the well-defined crystalline structure of these semiconductor materials, the thermal conductivity shows a magnitude and temperature dependence more typical of amorphous materials than crystalline materials. The localized low frequency vibrations of these “guest” ions is believed to interact with the acoustic phonons of the host lattice resulting in a very low thermal conductivity. Indeed in the case of Ge-clathrates a “glass-like” thermal conductivity was observed. The markedly low thermal conductivity displayed by these semiconductor materials, along with the high power factors, demonstrates the potential of this material system for thermoelectric applications.
Investigation of the Mechanism of the Enhanced Z3DT in PbTe Based Superlattices
Authors: Koga T. , Harman T. C. , Sun X. , Cronin S. B. , Dresselhaus M. S. 
Published: April 2011

AbstractVarious possible mechanisms for the recently discovered enhanced Seebeck coefficient S in PbTe/Te superlattices relative to the corresponding PbTe bulk are investigated. Among the various mechanisms which can account for the enhanced S, the energy dependent τ model (τ ∼ ɛr) seems the most plausible. Here the effective scattering parameter r is preferably increased due to the extra scattering by the periodic Te layers introduced in the superlattice. Other transport properties including the longitudinal magnetoresistance are also discussed.
Reliability of Thermal Conductivity Measured by Harman Method
Authors: Shinohara Y. , Imai Y. , Isoda Y. , Nishida I. A. 
Published: April 2011

AbstractThe Harman method was applied to measure thermal conductivity κ of thermoelectric materials, and the reliability of the measured κ was investigated. The quantitative κ requires a highly sensitive technique to measure minute Peltier heat. Temperature difference by Peltier heat pumping was successfully measured by developing the DC method of resistance measurement. κ ofn-type Bi2Te3sintered compact andn-type PbTe boules was measured at 295K by the Harman method. Static comparative method was also applied to obtain the standard value of κ. In the case of Bi2Te3, the κ by the Harman method agreed well with the standard value. In the case of PbTe in the electron concentrationnerange <5 × 1024/m3, the κ almost agreed with the standard value. However, PbTe in thenerange ≥1 × 1025/m3showed a larger κ than the standard value. The Harman method has an error to give the larger κ for the material with a large carrier component κ, of κ This error is due to the fast conduction of Peltier heat by the carrier. The reliable κ can be measured for the material with a small κ,.
Growth of Bismuth Telluride Thin Films by Hot Wall Epitaxy, Thermoelectric Properties
Authors: Tedenac J. C. , Corso S. Dal , Haidoux A. , Charar S. , Liautard B. 
Published: April 2011

AbstractIt is well known that bismuth telluride (Bi2Te3), its isomorphs (Bi2Se3 and Sb2Te3) and their alloys have the optimum bandgap (0.13 eV to 0.21 eV) for efficient solid state cooling applications around 300 K. Recently interesting work argued that the use of quantum well structures can enhance the figure of merit ZT as a result of the improvement of carrier charge density of state and the reduction of the thermal conductivity. However, for the production of such structures it is necessary to establish the optimum growth conditions and the doping levels of thin films based on Bi2Te3 and its isomorphs.In this paper we report on the growth characteristics of Bi2Te3 ternary alloys (even quaternary) thin films elaborated by the Hot Wall Epitaxy (HWE) technique. Ternary alloys based on bismuth telluride have been deposited as thin films on silicon and silica substrates. Hot Wall Epitaxy have been demonstrated to be a suitable technique in chalcogenides growth. These films are formed in a closed chamber, that make possible to keep substrates at relatively high temperature Ts without selective loss of individual components from condensate. Experimental procedures, such as substrate and source materials preparations, have been described in our previous publications. Thin films obtained are well oriented (001) and have block single-crystal structure. These films were studied by microstructural investigations and electrical measurements (electrical conductivity σ, Hall coefficient RH and Hall mobility μn) in the temperature range from liquid nitrogen to 570 K.
Thermoelectric Properties of PbTe/Pb1−x. Eux Te Quantum Wells
Authors: Scherrer H. , Dashevsky Z. , Kantser V. , Casian A. , Sur I. , Sandu A. 
Published: April 2011

AbstractThe electrical conductivity, Seebeck coefficient, and thermoelectric power factor of PbTe/Pb1−xEuxTe quantum well structures are investigated theoretically. The variational method is employed. The anisotropy of effective masses, the multivalley character of the bulk semiconductors and also the dependence of effective masses in dimensional quantization subbands on the well width are taken into account. The carrier scattering both on optical and acoustical phonons is considered for structures with (111) and (100) crystallographic orientation. It is found that the power factor is larger in (100) oriented quantum wells. The results of recent experiments are discussed.
Conformal Electroless Copper and Nickel Deposition on Mems Structures
Authors: Neves Hercules P. , Kudrle Thomas D. , Chen Jia-Ming , Adams Scott G. , Maharbiz Michel , Lopatin Sergey , MacDonald N. C. 
Published: April 2011

AbstractWe propose electroless metallization as a method for conformal metal deposition microelectromechanical systems (MEMS). The intrinsically conformal nature of electroless deposition makes it ideal for coating high aspect ratio (greater than 50:1) structures frequently fabricated with micromachining techniques We take advantage of the selective nature of the deposition to obtain self-aligned electrical isolation. We minimize the metal film roughness for potential applications in RF and optics. Given the specific MEMS metallization requirements, we determined the ideal concentrations of additives and surfactants in order to provide good electrical isolation, low roughness and high film reliability. Our depositions were done using seed layers as well as through direct chemical activation of the silicon surface. Characteristics such as resistivity [ 1 ], morphology [ 1 ], microstructure [ 2 ], and electrochemical behavior [ 3 ] have already been reported in the literature; our paper is focused on the specific requirements for MEMS applications.
Circuit Pattern cu Deposition on Polyimide Surface Using ArF Excimer Laser
Authors: Tomita M. , Murahara M. 
Published: April 2011

AbstractCircuit patterned nucleation of copper atoms onto polyimide surface was demonstrated by using ArF excimer laser (λ =193nm) and copper sulfate aqueous solution at an atmospheric pressure. Photo-excited C-H bonds of the polyimide surface were effectively dehydrated with hydrogen atoms which were photodissociated from the water. The dangling bonds of the dehydrated hydrogen atoms were combined with the oxygen and the copper atoms which were photodissociated by copper-sulfate aqueous solution. Thus, C-O-Cu bonds were formed on the surface. After this copper substitution, it was carried out onto the nucleated parts by usual electroless plating at 70°C. In this process, the conductive circuit pattern Cu thin film was deposited on polyimide surface.
A Novel Range of Noble Metal Organometallic Fluorides for use in the Fabrication of Submicron Metal Features by E-Beam or UV Irradiation
Authors: Thomson J. , Fzea A. H. , Lobban J. , McGivern P. , Cairns J. A. , Fitzgerald A. G. , Berry G. J. , Davidson M. R. , Fan Y. C. 
Published: April 2011

SummaryThe preparation a nd characterisationo f a novel organoplatinum fluoride is described. The physical vapour deposition (PVD) of the material was performed in the temperature range 160–170°C, and electron beam bombardment or uv irradiation, results in the degradation of the compound to give high quality metal features down to dimensions of ca 60 nm.
Sic Thin Film Characterization and Stress Measurements for High Temperature Sensors Applications
Authors: Gourbeyre C. , Aboughe-nze P. , Malhaire C. , Berre M. Le , Monteil Y. , Barbieri D. 
Published: April 2011

AbstractIn this work related to high temperature pressure sensors, a study was undertaken on the characterisation of β-SiC thin films through X-Ray Diffraction, AFM and stress measurements. 3C-SiC films were grown on (100) Si substrate in a vertical reactor by atmospheric-pressure chemical vapour deposition (APCVD). Silane and propane were used as precursor gas and hydrogen as carrier gas. Prior to the growth, Si surfaces were annealed at 1000°C for 5 minutes and carbonized with C3H8 at 1150°C during 10 minutes. At 1350°C, SiH4, C3H8 and H2 were introduced for the SiC deposition. The atomic ratio of Si/C in the gas phase was 0.3 and the growth rate was 3 μm/h. Only the process time was varying to obtain different SiC layer thicknesses varying from 3 to 9 μm as measured by FT-IR spectrometry. Stress measurements of thin β-SiC layers deposited on thick Si substrates were performed at room temperature using the bending plate method and the Stoney's equation. The stress for a 3 μm thick SiC layer is evaluated to be in the range of 400 MPa in tension. When increasing the SiC film thickness, this stress decreases due to the relaxation of the structure with bending. SiC/Si membranes were obtained by KOH etching and studied as a function of pressure in the [0-50 mbar] range. A residual stress in the membrane was deduced from the load-deflection measurement technique reaching 105 MPa in tension.
Synthesis, Structure and Dielectric Properties of Na2SnTeO6
Authors: Park J.-H. , Woodward P.M. , Parise J.B. , Lubomirsky I. , Stafsudd O. 
Published: April 2011

AbstractA new perovskite was recovered from the high pressure-high temperature treatment of the α-TlSbO3 form of Na2SnTeO6 at 7 GPa and 950 °C for 30 minutes. Synchrotron x-ray powder diffraction data show the space group is P21/n with a=5.40361 (5), b=5.46152(5), c=7.69288(7) Å and ß=90.034(3)°. Using disk samples of both polymorphs, the dielectric properties were measured as a function of temperature. At ambient conditions, the perovskite form has a more than 1.5 fold enhancement in dielectric constant compared to the α-TlSbO3 form while the molar volume and the molecular polarizability decrease.
New Substituted Pyrochlore-Type Manganates with Magnetoresistive Properties
Authors: Cheikh-Rouhou W. , Senis R. , Chaillout C. , Strobel P. , Martinez B. , Obradors X. 
Published: April 2011

AbstractSubstitutions in the pyrochlore-type oxide Tl2Mn2O7 have been carried out on both the Mn and the TI site, using high pressure synthesis at 4-6 GPa. We show that a continuous solid solution exists between Tl2Mn2O7, and Tl2Ru2O7, and that the replacement of a fraction of Mn by Ru dramatically changes the transport properties from metallic to semiconducting and induces magnetoresistance (MR) in this system. MRs up to 95% (vs. RO) have been observed. The Tl site, already known to accept In or Sc, can also be substituted by the larger cation Bi3+, which also induces a metal-insulator transition at low substitution level.
New Synthetic Pathways to Mesostructured Thiogermanates
Authors: Oberender N. , Fröba M. 
Published: April 2011

AbstractThe synthesis and characterisation of several mesostructured thiogermanates are shown. In particular the first supramolecular templated synthesis of mesostructured binary metal chalcogenides in a microwave is presented. The obtained products are characterised by x-ray powder diffraction, transmission electron microscopy, thermal analysis and x-ray absorption spectroscopy.
A New Type of Coordination Polymer: Hydrothermal Synthesis, Crystal Structure, and Magnetic Properties of [(C10H8N2)2CuBr]Cu3Br4
Authors: Cabrera Brenda R. , Wang Ru-Ji , Li Jing , Yuen Tan 
Published: April 2011

AbstractGrowth of [(C10H8N2)2CuBr]Cu3Br4(I) crystals was achieved using the hydrothermal synthesis. Single crystal X-ray diffraction analysis shows that this compound crystallizes in monoclinic system, space group P21/c (no. 14) with four formula units in the unit cell. The cell dimensions are the following: a = 16.769(2) Å, b = 23.873(6) Å, c = 6.523(2) Å, β = 98.37(3)°, V = 2584(1) Å3. The title compound represents a new structure type. It consists of one-dimensional ribbons of 1[(Cu3Br4)] extending along the c-axis and discrete [(C10H8N2)2CuBr]+ complexes. The magnetic susceptibility study indicates a paramagnetic behavior due to the Cu(II) in the complex cations. The effective paramagnetic moment was calculated to be 2.20 μB from fitting the χ(T) data.