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Articles 1 - 20 of 20
Full-Text Articles in Engineering Physics
Economics Of Nuclear Power And Climate Change Mitigation Policies, Nico Bauer, Robert Brecha, Gunnar Luderer
Economics Of Nuclear Power And Climate Change Mitigation Policies, Nico Bauer, Robert Brecha, Gunnar Luderer
Robert J. Brecha
The events of March 2011 at the nuclear power complex in Fukushima, Japan, raised questions about the safe operation of nuclear power plants, with early retirement of existing nuclear power plants being debated in the policy arena and considered by regulators. Also, the future of building new nuclear power plants is highly uncertain. Should nuclear power policies become more restrictive, one potential option for climate change mitigation will be less available. However, a systematic analysis of nuclear power policies, including early retirement, has been missing in the climate change mitigation literature. We apply an energy economy model framework to derive …
Density Functional Theory Study On The Electronic Structure Of N- And P-Type Doped Srtio3 At Anodic Solid Oxide Fuel Cell Conditions, S. Suthirakun, Salai Ammal, G. Xiao, Fanglin Chen, Hans-Conrad Zur Loye, Andreas Heyden
Density Functional Theory Study On The Electronic Structure Of N- And P-Type Doped Srtio3 At Anodic Solid Oxide Fuel Cell Conditions, S. Suthirakun, Salai Ammal, G. Xiao, Fanglin Chen, Hans-Conrad Zur Loye, Andreas Heyden
Salai C. Ammal
The electronic conductivity and thermodynamic stability of mixed n-type and p-type doped SrTiO3 have been investigated at anodic solid oxide fuel cell (SOFC) conditions using density functional theory (DFT) calculations. In particular, constrained ab initio thermodynamic calculations have been performed to evaluate the phase stability and reducibility of various Nb- and Ga-doped SrTiO3 at synthesized and anodic SOFC conditions. The density of states (DOS) of these materials was analyzed to study the effects of n- and p-doping on the electronic conductivity. In agreement with experimental observations, we find that the transformation from 20% Nb-doped Sr-deficient SrTiO3 to a non-Sr-deficient phase …
The Effect Of Copt Crystallinity And Grain Texturing On Properties Of Exchange-Coupled Fe/Copt Systems, H. Oguchi, A. Zambano, M. Yu, Jason Hattrick-Simpers, D. Banerjee, Y. Liu, Z. Wang, J. Liu, S. Lofland, D. Josell, I. Takeuchi
The Effect Of Copt Crystallinity And Grain Texturing On Properties Of Exchange-Coupled Fe/Copt Systems, H. Oguchi, A. Zambano, M. Yu, Jason Hattrick-Simpers, D. Banerjee, Y. Liu, Z. Wang, J. Liu, S. Lofland, D. Josell, I. Takeuchi
Jason R. Hattrick-Simpers
The effect of the crystallinity and the grain texturing of CoPt hard layers on exchange coupled Fe/CoPt soft/hard magnetic systems was studied using gradient thickness multilayer thin films. We have studied the hard layer structures by transmission electron microscopy and x-ray diffraction, and characterized the exchange coupling interaction through magnetization loops obtained by the magneto-optical Kerr effect measurement. We found that exchange coupling strongly depends on the crystalline characteristics of the CoPt hard layer. There is correlation between the mixture of different grain orientations of the CoPt hard layer and coupling efficiency. In particular, interlayer coupling is enhanced when there …
Rapid Structural Mapping Of Ternary Metallic Alloy Systems Using The Combinatorial Approach And Cluster Analysis, C. Long, Jason Hattrick-Simpers, M. Murakami, R. Srivastava, I. Takeuchi, V. Karen, X. Li
Rapid Structural Mapping Of Ternary Metallic Alloy Systems Using The Combinatorial Approach And Cluster Analysis, C. Long, Jason Hattrick-Simpers, M. Murakami, R. Srivastava, I. Takeuchi, V. Karen, X. Li
Jason R. Hattrick-Simpers
We are developing a procedure for the quick identification of structural phases in thin film composition spread experiments which map large fractions of compositional phase diagrams of ternary metallic alloy systems. An in-house scanning x-ray microdiffractometer is used to obtain x-ray spectra from 273 different compositions on a single composition spread library. A cluster analysissoftware is then used to sort the spectra into groups in order to rapidly discover the distribution of phases on the ternary diagram. The most representative pattern of each group is then compared to a database of known structures to identify known phases. Using this method, …
Note: A Simple Thermal Gradient Annealing Unit For The Treatment Of Thin Films, C. Metting, Johnathan Bunn, Ellen Underwood, Yihao Zhu, G. Koley, T. Crawford, Jason Hattrick-Simpers
Note: A Simple Thermal Gradient Annealing Unit For The Treatment Of Thin Films, C. Metting, Johnathan Bunn, Ellen Underwood, Yihao Zhu, G. Koley, T. Crawford, Jason Hattrick-Simpers
Jason R. Hattrick-Simpers
A gradient annealing cell has been developed for the high-throughput study of thermalannealing effects on thin-film libraries in different environments. The inexpensive gradientannealing unit permits temperature gradients as large as 28 °C/mm and can accommodate samples ranging in length from 13 mm to 51 mm. The system was validated by investigating the effects of annealing temperature on the crystallinity, resistivity, and transparency of tin-doped indium oxide deposited on a glass substrate by magnetron sputtering. The unit developed in this work will permit the rapid optimization of materials properties such as crystallinity, homogeneity, and conductivity across a variety of applications.
Characterization Of Magnetic Degradation Mechanism In A High Neutron-Flux Environment, Adib Samin, Jie Qiu, Jason Hattrick-Simpers, Liyang Dai-Hattrick, Yuan Zheng, Lei Cao
Characterization Of Magnetic Degradation Mechanism In A High Neutron-Flux Environment, Adib Samin, Jie Qiu, Jason Hattrick-Simpers, Liyang Dai-Hattrick, Yuan Zheng, Lei Cao
Jason R. Hattrick-Simpers
No abstract provided.
Optical Cell For Combinatorial In Situ Raman Spectroscopic Measurements Of Hydrogen Storage Materials At High Pressures And Temperatures, Jason Hattrick-Simpers, Wilbur Hurst, Sesha Srinivasan, James Maslar
Optical Cell For Combinatorial In Situ Raman Spectroscopic Measurements Of Hydrogen Storage Materials At High Pressures And Temperatures, Jason Hattrick-Simpers, Wilbur Hurst, Sesha Srinivasan, James Maslar
Jason R. Hattrick-Simpers
An optical cell is described for high-throughput backscattering Raman spectroscopic measurements of hydrogen storagematerials at pressures up to 10 MPa and temperatures up to 823 K. High throughput is obtained by employing a 60 mm diameter × 9 mm thick sapphire window, with a corresponding 50 mm diameter unobstructed optical aperture. To reproducibly seal this relatively large window to the cell body at elevated temperatures and pressures, a gold o-ring is employed. The sample holder-to-window distance is adjustable, making this cell design compatible with optical measurement systems incorporating lenses of significantly different focal lengths, e.g., microscope objectives and single element …
Temperature Distribution In An Oscillatory Flow With A Sinusoidal Wall Temperature, Eduardo Ramos, Brian Storey, Fernando Sierra, Raul Zuniga, Andriy Avramenko
Temperature Distribution In An Oscillatory Flow With A Sinusoidal Wall Temperature, Eduardo Ramos, Brian Storey, Fernando Sierra, Raul Zuniga, Andriy Avramenko
Brian Storey
The temperature field generated by an oscillatory boundary layer flow in the presence of a wall with a sinusoidal temperature distribution is analyzed. A linear perturbation method is used to find closed form analytical solutions for the temperature field when the amplitude of the velocity oscillation is small. The analytical solutions only consider long-time behavior when the temperature fields oscillate with the frequency of the flow. The structure of the equation that governs the temperature correction due to convection is similar to that of diffusive waves with the solution consisting of traveling or standing waves. The temperature distribution is also …
Low-Temperature Ferromagnetic Properties Of The Diluted Magnetic Semiconductor Sb2-X Crx Te3 ., Jeffrey Dyck, Č. Drašar, P. LošŤÁK, C. Uher
Low-Temperature Ferromagnetic Properties Of The Diluted Magnetic Semiconductor Sb2-X Crx Te3 ., Jeffrey Dyck, Č. Drašar, P. LošŤÁK, C. Uher
Jeffrey Dyck
We report on magnetic and electrical transport properties of Sb2-x Crx Te3 single crystals with 0⩽x⩽0.095 over temperatures from 2 K to 300 K . A ferromagnetic state develops in these crystals at low temperatures with Curie temperatures that are proportional to x (for x>0.014 ), attaining a maximum value of 20 K for x=0.095 . Hysteresis below TC for the applied field parallel to the c axis is observed in both magnetization and Hall-effect measurements. Magnetic as well as transport data indicate that Cr takes the 3+ (3 d3 ) valence state, substituting for antimony in the host …
Micro Thermoelectric Cooler Fabrication: Growth And Characterization Of Patterned Sb2te3 And Bi2te3 Films ., Luciana Da Silva, M. Kaviany, A. Dehennis, Jeffrey Dyck
Micro Thermoelectric Cooler Fabrication: Growth And Characterization Of Patterned Sb2te3 And Bi2te3 Films ., Luciana Da Silva, M. Kaviany, A. Dehennis, Jeffrey Dyck
Jeffrey Dyck
A column-type micro thermoelectric cooler is being fabricated using p-type Sb2Te3 and n-type Bi2Te3 films (approximately 4 μm thick). The films are grown by thermal co-evaporation and patterned on Cr/Au/Ti/Pt (hot) connectors, which are deposited onto a silicon dioxide coated wafer. The column height is limited by control of the Te deposition rate. Although a high substrate temperature during thermoelectric film deposition is desired, it has been limited by the degradation of the photoresist used for patterning. The measured Seebeck coefficient and electrical resistivity of the thermoelectric films are reported, and preliminary results show that excess tellurium increases the Seebeck …
Transport Coefficients Of Titanium-Doped Sb2te3 Crystals., P. Svanda, P. LošŤÁK, Č. Drašar, Jeffrey Dyck
Transport Coefficients Of Titanium-Doped Sb2te3 Crystals., P. Svanda, P. LošŤÁK, Č. Drašar, Jeffrey Dyck
Jeffrey Dyck
Titanium-doped single crystals (cTi = 0 to 2×1020 atoms cm-3) were prepared from the elements Sb, Ti, and Te of 5N purity by a modified Bridgman method. The obtained crystals were characterized by measurements of the temperature dependence of the electrical resistivity, Hall coefficient, Seebeck coefficient and thermal conductivity in the temperature range of 5-300 K. It was observed that with an increasing Ti content in the samples the electrical resistance, the Hall coefficient and the Seebeck coefficient increase. This means that the incorporation of Ti atoms into the Sb2Te3 crystal structure results in a decrease in the concentration of …
Electrical Conductivity And Thermopower Of Cu–Sio[Sub 2] Nanogranular Films., W. Chen, J. Lin, X. Zhang, H. Shin, Jeffrey Dyck, C. Uher
Electrical Conductivity And Thermopower Of Cu–Sio[Sub 2] Nanogranular Films., W. Chen, J. Lin, X. Zhang, H. Shin, Jeffrey Dyck, C. Uher
Jeffrey Dyck
We have measured the thermopower S and electrical conductivity σ in a series of Cu[sub x](SiO[sub 2])[sub 1-x] nanogranular films between 2 and 300 K with Cu volume fraction x varying from 0.43 up to 1.0. At low temperatures, disorder-enhanced electron-electron interaction effects dictate the behavior of σ. A crossover of the temperature dependence from σ∝ √T to σ∝ T[sup 1/3] is observed as x is lowered and the metal-insulator transition is approached. S is small, shows linear temperature dependence, and is rather insensitive to the change of x. Effects of annealing are also discussed.
Anomalous Barium Filling Fraction And N-Type Thermoelectric Performance Of Ba[Sub Y]Co[Sub 4]Sb[Sub 12]., L. Chen, T. Kawahara, X. Tang, T. Goto, T. Hirai, Jeffrey Dyck, W. Chen, C. Uher
Anomalous Barium Filling Fraction And N-Type Thermoelectric Performance Of Ba[Sub Y]Co[Sub 4]Sb[Sub 12]., L. Chen, T. Kawahara, X. Tang, T. Goto, T. Hirai, Jeffrey Dyck, W. Chen, C. Uher
Jeffrey Dyck
Barium-filled skutterudites BaCoSb with an anomalously large filling fraction of up to y=0.44 have been synthesized. The lattice parameters increase linearly with Ba content. Magnetic susceptibility data show that BaCoSb is paramagnetic, which implies that some of the Co atoms in BaCoSb have acquired a magnetic moment. The presence of the two different valence states of Co (Co3+ and Co2+) leads to the anomalously large barium filling fraction even without extra charge compensation. All samples show n-type conduction. The electrical conductivity increases with increasing the Ba filling fraction. The lattice thermal conductivity of BaCoSb is significantly depressed as compared to …
Low Temperature Thermoelectric Properties Of Ni Doped N-Type Filled Skutterudites Ba0.3co4sb12 ., W. Chen, Jeffrey Dyck, C. Uher, L. Chen, X. Tang, T. Hirai
Low Temperature Thermoelectric Properties Of Ni Doped N-Type Filled Skutterudites Ba0.3co4sb12 ., W. Chen, Jeffrey Dyck, C. Uher, L. Chen, X. Tang, T. Hirai
Jeffrey Dyck
n-type Ba filled skutterudites doped with Ni, Ba0.3Ni xCo4-xSb12 with 0⩽x⩽0.2, have been synthesized and the Seebeck coefficient, thermal conductivity, electrical resistivity and Hall coefficient have been measured. ZT of 1.2 has been achieved at 800 K with x=0.05. The thermal conductivity data are fitted and the rattling effect of the Ba atoms is identified through a resonance scattering term. The Hall mobility is studied and a mixed scattering mechanism of acoustic phonons and ionized impurities based on a single, rigid band picture is presented. The role of Ni atoms in enhancing the thermoelectric performance is discussed
Multi-Filling Approach For The Improvement Of Thermoelectric Properties Of Skutterudites., L. Chen, X. Tang, T. Kawahara, Jeffrey Dyck
Multi-Filling Approach For The Improvement Of Thermoelectric Properties Of Skutterudites., L. Chen, X. Tang, T. Kawahara, Jeffrey Dyck
Jeffrey Dyck
Several skutterudite antimonides filled with atoms of different kinds, (Ba, M)yCo4Sb12 (M=Ce, La, Sr), have been synthesized by the combination of solid state reaction and melting methods. Thermal conductivity of (Ba,Sr)yCo4 Sb12 samples shows a behavior similar to that of BayCo4Sb12. Adding a small amount of Ce or La to the BayCo4Sb12 system is effective in further reducing the lattice thermal conductivity. The difference in the ionic radii of the two co-filler atoms is the most sensitive factor for scattering of phonons. The multi-filled (Ba, M)yCo4Sb12 (M=Sr, Ce, La) show lower Seebeck coefficients as compared to the single-filled BayCo 4Sb12 …
High-Temperature Thermoelectric Properties Of N-Type Baynixco4-Xsb12., X. Tang, L. Zhang, R. Yuan, L. Chen, T. Goto, T. Hirai, Jeffrey Dyck, W. Chen, C. Uher
High-Temperature Thermoelectric Properties Of N-Type Baynixco4-Xsb12., X. Tang, L. Zhang, R. Yuan, L. Chen, T. Goto, T. Hirai, Jeffrey Dyck, W. Chen, C. Uher
Jeffrey Dyck
Effects of Ba filling fraction and Ni content on the thermoelectric properties of n-type BayNixCo4-xSb12 (x = 0-0.1, y = 0.-0.4) were investigated at temperature range of 300 to 900 K. Thermal conductivity decreased with increasing Ba filling fraction and temperature. When y was fixed at 0.3, thermal conductivity decreased with increasing Ni content and reached a minimum value at about x = 0.05. Lattice thermal conductivity decreased with increasing Ni content, monotonously (y ≤ 0.1). Electron concentration and electrical conductivity increased with increasing Ba filling fraction and Ni content. Seebeck coefficient increased with increasing temperature and decreased with increasing …
Synthesis And High Temperature Thermoelectric Properties Of N-Type Baynixco4-Xsb12., X. Tang, L. Chen, T. Goto, Jeffrey Dyck
Synthesis And High Temperature Thermoelectric Properties Of N-Type Baynixco4-Xsb12., X. Tang, L. Chen, T. Goto, Jeffrey Dyck
Jeffrey Dyck
Single-phase filled skutterudite compounds BayNx Co4-xSb12 (x=0-0.1, y=0-0.4) were synthesized by a two-step solid state reaction. Effects of Ba filling fraction and Ni content on the thermoelectric properties of n-type Ba yNixCo4-xSb12 were investigated. Thermal conductivity decreased with increasing Ba filling fraction and temperature. When barium filling fraction (y) was fixed at 0.3, the thermal conductivity decreased with increasing Ni content, and reached a minimum value at about x=0.05. Electron concentration and electrical conductivity increased with increasing Ba filling fraction and Ni content. Seebeck coefficient increased with increasing temperature, and decreased with increasing Ba filling fraction and Ni content. A …
Thermoelectric Properties Of Yb-Filled And Sn-Compensated Skutterudites ., Jihui Yang, Gregory Meisner, Wei Chen, Jeffrey Dyck, Ctirad Uher
Thermoelectric Properties Of Yb-Filled And Sn-Compensated Skutterudites ., Jihui Yang, Gregory Meisner, Wei Chen, Jeffrey Dyck, Ctirad Uher
Jeffrey Dyck
The effect of alloying tin on the antimony site of ytterbium-filled skutterudites is examined. We performed measurements of Hall effect, electrical resistivity, Seebeck coefficient and thermal conductivity on the series Yb0.5Co4Sb12-x Snx, with x=0.5, 0.6, 0.8 and 0.83. We find that the substitution of tin does not alter the position of the Fermi level with respect to the conduction band of these heavily doped semiconducting samples, but rather it gives rise to a p-type band. Experimental data for x=0.83 can be understood in the context of a two-carrier electrical conduction. Thermal conductivity of these ytterbium-filled skutterudites is significantly suppressed with …
Transport And Magnetic Properties Of Co1-Xnixsb3 With X Less Than 0.01, Jeffrey Dyck, W. Chen, Y. Yang, G. Meisner, C. Uher
Transport And Magnetic Properties Of Co1-Xnixsb3 With X Less Than 0.01, Jeffrey Dyck, W. Chen, Y. Yang, G. Meisner, C. Uher
Jeffrey Dyck
The filled skutterudite compounds based on the binary skutterudite CoSb3 are currently being investigated for their potential application as thermoelectric materials. One route to optimization of these compounds is by doping on the Co site. An obvious candidate for an n-type dopant is Ni, because it has one more electron in its valence shell than Co. We present electrical resistivity, thermopower, Hall effect and magnetic susceptibility measurements on polycrystalline, n-type Co1-xNixSb3 with x less than 0.01. A model which takes into account conduction of electrons residing in the conduction band in addition to hopping conduction within an impurity "band" formed …
Synthesis Of Bulk Polycrystalline Indium Nitride At Subatmospheric Pressures., Jeffrey Dyck, K. Kash, C. Hayman, A. Argoitia, M. Grossner, J. Angus, W.-L. Zhou
Synthesis Of Bulk Polycrystalline Indium Nitride At Subatmospheric Pressures., Jeffrey Dyck, K. Kash, C. Hayman, A. Argoitia, M. Grossner, J. Angus, W.-L. Zhou
Jeffrey Dyck
Polycrystalline, wurtzitic indium nitride was synthesized by saturating indium with nitrogen from microwave plasma sources. The structure was confirmed by x-ray diffraction, electron diffraction, and elemental analysis. Two types of growth were observed: (i) dendritic crystals on the original melt surface, and (ii) hexagonal platelets adjacent to the In metal source on the upper edge of the crucible. The method does not involve a foreign substrate to initiate growth and is a potential alternative to the high-pressure techniques normally associated with bulk growth of indium nitride. The lattice parameters were a = 3.5366 ± 0.0005 angstrom and c = 5.7009 …