bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reduction of Environmental Impacts in Crystalline Silicon Photovoltaic Technology: An Analysis of Driving Forces and Opportunities
Authors: Alsema Erik , de Wild-Scholten Mariska 
Published: April 2011

AbstractWe give an overview of historical developments with respect to the price and the Energy Pay-Back Time of crystalline silicon photovoltaic modules. We investigate the drivers behind both developments and observe that there is a large overlap between them. Reduction of silicon consumption, improved cell efficiency and the production technology for solar grade silicon have been identified as major drivers for both cost and impact reductions in the past. Also we look into future prospects for reduction of environmental impacts. It is estimated that developments underway to reduce costs will also result in a reduction of the Energy Pay-Back Time of a PV installation (in South-Europe) from 1.5-2.0 year presently to well below 1 year.
Ir based photovoltaic array performance assessment
Authors: Moropoulou Antonia , Palyvos J. A. , Karoglou M. , Panagopoulos V. 
Published: April 2011

AbstractIn this work infrared thermography was used as a diagnostic tool for the performance assessment of a photovoltaic array integrated on the southern façade of NTUA's Chemical Engineering Building. This grid-connected 50 kWp solar photovoltaic array, installed under an EC Thermie Project (SE-142-97-GR-ES), operates in a standard and hybrid PV-Thermal configuration, meant to save conventional energy. The thermographic system used for the analysis covers the 8-12 ìm of wavelength region. The thermal images obtained showed that there are temperature differences on the PV panels, which may be attributed to PV material defects, manufacturing faults, external abuse, or PV malfunction.
Integration of Land Use Aspects into Life Cycle Assessment at the Example of Biofuels
Authors: Held Michael , Bos Ulrike 
Published: April 2011

AbstractIt is well known that the transport sector causes significant environmental impacts worldwide and as a consequence influences the results of Life Cycle Assessment (LCA) studies. Today's fuels are dominated by crude oil derived fuels. In Europe currently 98 % of the road transportation is based on such crude oil derived fuels. Similar ratios can be observed e.g. in the US and other countries. In addition to the environmental impacts, the high dependency on the imports of fossil fuels motivates most European countries to investigate in other than fossil fuel based transport systems. Therefore the European Commission presented an action plan including a strategy with the objective to substitute 20% of crude oil derived fuels by alternative fuel until 2020. To achieve these goals, actions to reduce the import dependency of fuels, the usage of non renewable (fossil) resources and the environmental burdens connected to the use of fuel / propulsion systems have to be addressed. Besides, the energy carrier mix has to be broadened. Especially alternative fuels from renewable resources, BtL (Biomass to Liquid) are supposed to have a high potential.Recent developments show, that there is a variety of options for fuels available as well as for propulsion technologies that utilize fuels based on renewable resources. It is therefore of key importance to select and promote the fuel/ propulsion system technology which is most beneficiary for a country or region from an environmental but also from an economic and social perspective. For such a sustainability evaluation it is essential to consider the local/regional boundary conditions such as availability of fuel resources, major pollution issues which need to be addressed, supply of secondary energy (e.g. power) etc. LCA is therefore a suitable approach to evaluate and compare different options, due to its transparent consideration of all life cycle stages.Besides the environmental impacts and resource consumption which are addressed in LCA considerations the needed land is another important aspect when talking about biomass as a resource. As land is a scarce resource that is used for all industry sectors there is a need to address this issue also in LCA. Up to now, no commonly agreed upon methods exist which allow the integration of land use aspects in a consistent way into LCA Software and Database. Currently at LBP-GaBi, University of Stuttgart together with PE International, a method is developed to integrate land use aspects into LCA. Backward processes are now implemented in an applicable way into a LCA database system.This Paper describes the main approach of the developed methodology for land use consideration within LCA.
Composition Dependence of Electrical Resistivity of Magnesium-cobalt Films During Hydridation and Dehydridation
Authors: Chan Yiu Bun , Ong Chung Wo 
Published: April 2011

AbstractPalladium (Pd)-coated magnesium-cobalt (Mg-Co) films were prepared by co-sputtering at various ratios of the sputtering power of Mg to that of Co (PMg/PCo). The elemental composition of the films varies coherently with PMg/PCo. Films of higher Mg contents are of stronger interest. Their structures are more disordered even when just a relatively small amount of Co is added. The respective elemental contents are not uniform along depth, but more Mg aggregate near the surface region. A substantial volume fraction of Mg oxide is present. Though of structural complications, a Mg-rich film shows stronger and faster resistivity (ρ) response when reacting with hydrogen. Soaking an as-deposited Mg-rich film in 15% H2 (in argon) gives a huge change of ρ by 40 times, but it is mainly due to some irreversible structural change when a freshly prepared sample is first brought into contact with H2. The change of ρ in subsequent hydridation-dehydridation cycles is about 50%, while the drift of the baseline is less severe. Co-rich films give much weaker resistivity response to H2.
Preparation of Nitride Fuel by Spark Plasma Sintering Technique
Authors: Muta Hiroaki , Kurosaki Ken , Uno Masayoshi , Yamanaka Shinsuke 
Published: April 2011

AbstractSPS technique was applied for fabrication of UN pellets. The dense sample was obtained with relatively low sintering temperature without any milling process and sintering additive, indicating that the SPS technique is suitable for fabrication of nitride fuel. The thermal conductivity and Young's modulus in axial direction were higher than those of reported values. EBSP analysis and electronic calculation supposed that weak grain orientation in [100] direction of the sample lead to these higher values.
Large thermoelectric power generated by the van Hove singularity in NaxCoO2
Authors: Takeuchi Tsunehiro , Kuno Syuhei 
Published: April 2011

AbstractMechanism leading to the large thermoelectric power and metallic electrical conduction observed in NaxCoO2 was investigated by means of angle resolved photoemission spectroscopy and the Bloch-Boltzmann theory. As a result of thermoelectric power calculation using the experimentally determined electronic structure under the assumptions of rigid band and constant mean free path, NaxCoO2 were found to possess the Boltzmann-type electrical conduction over a wide carrier-concentration range. Analysis using the simplest tight-binding bands revealed that the two-dimensional hexagonal lattices including the crystalline structure of the present NaxCoO2 produce a characteristic spectral conductivity leading to the large thermoelectric power and metallic electrical conduction.
Mechanical Alloying Synthesis of K2Bi8Se13– type Solid Solutions
Authors: Toumpas Nikolaos , Kyratsi Theodora , Hatzikraniotis Euripides , Tsiappos Andreas , Pavlidou Eleni , Paraskevopoulos Konstantinos M. , Chung Duck Young , Kanatzidis Mercouri G. 
Published: April 2011

AbstractSolid solutions of β-K2Bi8-xSbxSe13are an interesting series of materials for thermoelectric investigations due to their very low thermal conductivity and highly anisotropic electrical properties. In this work, we aimed to synthesize solid solutions of β-K2Bi8-xSbxSe13type materials using powder techniques. The synthesis was based on mechanical alloying as well as sintering procedures. The products were studied in terms of structural features, composition and purity with powder x-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. Preliminary results on thermoelectric properties as well as IR reflectivity measurements are presented.
Structural Studies of GeTe-AgSbTe2 Alloys
Authors: Thompson Alan , Sharp Jeff , Rawn C.J , Chackoumakos B.C. 
Published: April 2011

AbstractGeTe, a small bandgap semiconductor that has native p-type defects due to Ge vacancies, is an important constituent in the thermoelectric material known as “TAGS” [1]. TAGS is an acronym for alloys of GeTe with AgSbTe2, and compositions are normally designated as TAGS-x, where x is the fraction of GeTe. TAGS-85 is the most important with regard to applications, and there also is commercial interest in TAGS-80. The crystal structure of GeTe1+δ has a composition-dependent phase transformation at a temperature ranging from 430°C (δ = 0) to ∼ 400°C (δ = 0.02) [2]. The high temperature form is cubic. The low temperature form is rhombohedral for δ < 0.01, as is the case for good thermoelectric performance. Addition of AgSbTe2 shifts the phase transformation to lower temperatures, and one of the goals of this work is a systematic study of the dependence of transformation temperature on the parameter x. We present results on phase transformations and associated instabilities in TAGS compositions in the range of 70-85 at.% GeTe.
Mechanical Characterization of PbTe-based Thermoelectric Materials
Authors: Ren Fei , Hall Bradley D , Ni Jennifer E , Case Eldon D , Sootsman Joe , Kanatzidis Mercouri G , Lara-Curzio Edgar , Trejo Rosa M , Timm Edward J 
Published: April 2011

AbstractPbTe-based thermoelectric (TE) materials exhibit promising thermoelectric properties and have potential applications in waste heat recovery from sources such as truck engines and shipboard engines. TE components designed for these applications will be subject to mechanical/thermal loading and vibration as a result from in-service conditions, including mechanical vibration, mechanical and/or thermal cycling, and thermal shock.In the current study, we present and discuss the mechanical properties of several PbTe-based compositions with different dopants and processing methods, including n-type and p-type specimens fabricated both by casting and by powder processing. Room temperature hardness and Young's modulus are studied by Vickers indentation and nanoindentation while fracture strength is obtained by biaxial flexure testing. Temperature dependent Young's modulus, shear modulus, and Poisson's ratio are studied via resonant ultrasound spectroscopy (RUS).
Design and evaluation of n-type Si1-xGex as a thermoelectric-conversion material
Authors: Imai Tomohiro , Iida Tsutomu , Miyata Yuki , Itoh Takashi , Funashima Hiroki , Takanashi Yoshifumi , Hamada Noriaki 
Published: April 2011

AbstractSi1-xGex alloys show the high power generating efficiency as a thermoelectric- conversion material. We evaluate the thermoelectric power of the n-type SiGe system on the basis of the first principles calculations. The electronic-band-structure calculation is performed using all-electron full-potential linearized augmented-plane-wave (FLAPW) method within the local density approximation (LDA). The Seebeck coefficient is analyzed by the Bloch-Boltzmann equation. We find that the ordered rhombohedral SiGe has high Seebeck coefficient in comparison with zincblende SiGe. The efficiency of the thermoelectric power in Si1-xGex is gained by the local atomic configuration rather than the Ge concentration.
Optimization of Thermoelectric Properties of Ni-Cu based Alloy through Combinatorial Approach
Authors: Yamamoto Atsushi , Obara Haruhiko , Ueno Kazuo 
Published: April 2011

AbstractThe thermoelectric properties of Ni1-xCux (0<x<1) alloy are measured from 323K to 950K. The sample with optimized composition, Ni70Cu30 is found to possess large power factor value of 0.012 Wm−1K−2 at around 950K. Estimated figure of merit value ZT is 0.21 for Ni50Cu50 and 0.18 for Ni70Cu30 at the same temperature. A novel attempt of high-throughput parallel synthesis using multiple-wells is carried out to test the feasibility of combinatorial approach in this material system. The Seebeck coefficient is visualized over the multiple-wells combinatorial library and the other Ni-Cu composition-spread, and it is proved that further enhancement of throughput could be possible by conducting systematic experiments based on the combinatorial approaches performed in this study.
Thermoelectric and Mechanical Properties of Ca0.9Yb0.1MnO3 Based Materials
Authors: Kosuga Atsuko , Urata Saori , Funahashi Ryoji 
Published: April 2011

AbstractThe Ca0.9Yb0.1MnO3/Ag composites(the ratio of Ag to Ca0.9Yb0.1MnO3 was 0, 4.7, 9.4, and 18.8 wt %) were prepared by wet milling various amounts of Ca0.9Yb0.1MnO3 and Ag2O powder mixtures followed by sintering in order to improve the mechanical properties of Ca0.9Yb0.1MnO3 for n-type legs of thermoelectric oxide devices. The obtained composites consisted of two phases such as Ca0.9Yb0.1MnO3 and metallic silver from the X-ray diffraction (XRD) analysis. The scanning electron microscope (SEM) analysis indicated that the Ag particles, the size of which was within 5 μm, were homogeneously dispersed in Ca0.9Yb0.1MnO3 matrix for all the composites. The σf of 18.8 wt% Ag composite became 251 MPa, which was 2 times larger value than that of Ca0.9Yb0.1MnO3. The power factor (S2ρ) was slightly improved by the addition of silver particles. The maximum S2ρ, i.e. 0.26 mWm-1K-2 at 573 K was obtained for 18.8 wt% Ag composite.
Thermoelectric Properties and Magnetic Anisotropies of Magnetically Grain-Oriented Sr- or Bi-doped Ca3Co4O9 Thick Films
Authors: Horii Shigeru , Yamasaki Yuhya , Sakurai Masayuki , Funahashi Ryoji , Uchikoshi Tetsuo , Suzuki Tohru S , Sakka Yoshio , Ogino Hiraku , Shimoyama Jun-ichi , Kishio Kohji 
Published: April 2011

AbstractWe report magnetic properties of [Ca2CoO3-δ]0.62CoO2 (Ca349) powders with various average size and the Bi- and Sr-doping effects on thermoelectric properties for the magnetically grain-aligned and densified Ca349 thick films. Magnetic anisotropy at 300 K depended on the initial average size of Ca349 powders and decreased with the decrease in the size. This presumably suggests that distortion of crystal structure was induced by a ball-milling process and led to the change of magnetic anisotropy. On the Bi- and Sr-doping effects, an obvious enhancement of thermoelectric properties did not emerge in the case of the Sr-doping, whereas the enhancement was observed for the Bi-doped Ca349 thick films. However, a drastic decrease of magnetic anisotropy was caused by the Bi-doping. For usage of the p-type layer in multilayered thermoelectric module, tuning of the Bi-doping levels in which both enhancement of thermoelectric properties and a certain level of magnetic anisotropy are achieved is required.
Electrical Contact Fabrication and Measurements of Metals and Alloys to Thermoelectric Materials
Authors: D'Angelo Jonathan James , Timm Edward J , Ren Fei , Hall Bradley D , Case Eldon , Schock Harold , Kanatzidis Mercouri , Chung Duck Young , Hogan Timothy P 
Published: April 2011

AbstractLow electrical contact resistance is essential for the fabrication of high efficiency thermoelectric generators in order to convert heat to electricity. These contacts must be stable to high temperatures and through thermal cycling. A ratio of the contact resistance to the leg resistance below 0.1 is the goal for fabrication of a high efficiency thermoelectric power generation device. Here we present the fabrication procedures and characterization of contacts of metal alloys to Pb-Sb-Ag-Te (LAST) and Pb-Sb-Ag-Sn-Te (LASTT) compounds. Contacts were fabricated and measured for both ingot and hot pressed materials. Stainless steel 316 has shown a low resistance contact to these thermoelectric materials when the proper bonding conditions are used. Different time-temperature-pressure conditions for bonding to n-type and to p-type legs are presented. Contact resistances below 10μΩcm2 have been measured. In addition, break tests have shown bond strengths exceeding the semiconductor fracture strength. One of the considerations used in selecting iron alloys for electrical interconnects is the similarity in the coefficient of thermal expansion to the LAST and LASTT materials which is 18 ppm/°C and relatively temperature insensitive. Contacts to the thermoelectric materials were accomplished by diffusion bonding in a furnace developed in our lab at Michigan State University. The furnace is capable of reaching temperatures of up to 1000°C with a controlled atmosphere of a reducing gas. Fabrication procedures and contact data are presented in this paper.
Kinetics of the remediation of Arsenic-contaminated groundwater using nanoscale magnetite particles
Authors: Hari Parameswar , Isley Aaron , Medders Greg , Purser Gordon 
Published: April 2011

AbstractArsenate species are toxic compounds widely found as contaminants in industrial and metallurgical environments. Environmental health problems related to industrial waste streams and related drinking water contaminations can commonly occur. Around the world, from Bangladeshi water wells to Oklahoman metal plating sites, toxic levels of arsenic (As) leach into potable water. This paper describes a flow loop system that relies on magnetic nanoscale particles, iron oxide (nanorust), for the removal of these toxic metals. The nanorust particles have an extremely high surface area which allows for the rapid removal of these metal oxides. Perhaps even more importantly, nanorust (iron oxide) also has the unique advantage that it can be easily removed and re-concentrated using inexpensive low field magnetic (125 T) separation techniques. In this study we will present results on treating low levels of As in water with nano particles of mesh size at 50 nm and 26 nm. Determination of As concentrations below 100 ppb level was attained using an Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) system and a continuous flow loop system.
EXPERIMENTAL OBSERVATIONS OF THE FAILURE MECHANISMS IN A BULK METALLIC GLASS COMPOSITE
Authors: Wang Hui , Bastawros Ashraf , Biner S. Bulent 
Published: April 2011

AbstractThe deformation and damage evolution behavior of a Ni-based bulk metallic glass composite reinforced with elongated brass phase is studied under cylindrical indentation. The estimated fracture toughness values based on the energy dissipation and the in-situ observation during the loading reveal the details of the damage evolution and toughening mechanisms in this composite system. The results indicate that the enhanced toughness of the BMG composite is plausibly an outcome of crack bridging mechanisms by the ductile brass phase, rather than a diffused array of nucleated shear bands in the hard BMG and arrest by the ductile reinforcing phase.
Nanometer-scale Structural Relaxation in Zr-based Bulk Metallic Glass
Authors: Hwang Jinwoo , Cao Hongbo , Voyles Paul M. 
Published: April 2011

AbstractWe investigated the influence of annealing on the nanometer-scale medium-range order in Zr54Cu38Al8 bulk metallic glass using fluctuation electron microscopy. Fluctuation microscopy experiments probing structure at a length scale of 1 nm show that the as-cast Zr bulk metallic glass contains significant medium range order. That structure is unchanged by annealing at 87% of the glass transition temperature for 24 hours, although that anneal does significantly change the differential scanning calorimetry trace.
Influence of Co Addition on Magnetic Properties and Glass Formation of Fe-based Amorphous Alloys
Authors: Piccin Rafael , Tiberto Paola , Lupu Nicoleta , Chiriac Horia , Baricco Marcello 
Published: April 2011

AbstractIn the present work, the influence of Co addition on the glass forming ability (GFA) and magnetic properties of the ((Fe1−xCox)75B20Si5)93Nb4Y3 (x = 0, 0.2, 0.4, 0.5, 0.6, 0.8, 1) alloy is evaluated. Ribbons and 1 mm diameter ingots were prepared by melt-spinning technique and Cu-mold injection casting technique, respectively. The presence of the amorphous phase was confirmed through X-ray diffraction and high temperature differential scanning calorimetry (HT-DSC). Rapid solidification leads to fully amorphous ribbons for all compositions. Conversely, ingots with Co content with x > 0.5 present boride crystalline phases.Magnetization measurements were performed by means of vibration sample magnetometer in a temperature range from room temperature to 850 °C in order to determine the Curie temperature (TC) of the amorphous phase and to follow the formation of magnetic phases at high temperatures. In addition, hysteresis loops measurements were carried out to study the magnetic response of the samples. Co substitution until x = 0.5 is seen to simultaneously induce in the as cast ingots a decrease of coercive field from 52 to around 10 A/m and an increase of the Curie temperature of the amorphous phase from 480 to 700 K. A maximum saturation magnetization value of 123 emu/g was observed in the sample having x = 0.2. The role of Co substitution on glass formation is discussed on the basis of crystallization and melting behaviors, analyzed by HT-DSC. Magnetic properties are correlated with the presence of crystalline phases and their microstructures.
Preparation of Zr-based Metallic Glass Wire for Biomedical Application
Authors: Nagase Takeshi , Kinoshita Koichi , Umakoshi Yukichi 
Published: April 2011

AbstractNew Zr based metallic glass wires without bio-toxic elements of Ni, Al and Be were devel-oped for the further application as biomaterials by arc-melting type melt-extraction method. The continuous metallic glass wires with a good white luster and smooth surface were obtained in Zr-Ti-Al-Co, Zr-Al-Co-Cu, Zr-Al-Co and Zr-Ti-Co alloys. The Zr-based metallic glass wires show high tensile strength reaching 1000MPa. Furthermore, the wires exhibit good bending duc-tility and can be bent through 180 degrees without fracture. The Zr-based metallic glass wires achieve simultaneously high tensile strength, good bending ductility and high thermal stability.
Fracture Toughness Study on Zr-based Bulk Metallic Glasses
Authors: Suh Jin-yoo , Lind Mary Laura , Kim C. Paul , Conner R. Dale , Johnson William L 
Published: April 2011

AbstractThe fracture toughness of Zr-based bulk metallic glasses of various compositions was studied in the as-cast and annealed condition. Properties were characterized using x-ray and differential scanning calorimetry (DSC) and fracture surfaces were examined using electron microscopy (SEM). Quaternary Zr-Ti-Cu-Be alloys consistently had linear elastic fracture toughness values greater than 80 MPa·m1/2, while Vitreloy 1, a Zr-Ti-Cu-Ni-Be alloy, had an average fracture toughness of 48.5 MPa·m1/2 with a large amount of scatter. The addition of iron to Vitreloy 1 reduced the fracture toughness to 25 MPa·m1/2. Fracture surfaces were carefully analyzed using electron microscopy. Some samples had highly jagged patterns at the beginning stage of crack propagation, and the roughness of this jagged pattern correlated well with the measured fracture toughness values. These jagged patterns, the main source of energy dissipation in the sample, were attributed to the formation of shear bands inside the sample. The Zr-Ti-Cu-Be alloy, having KQ=85 MPa·m1/2 as cast, was annealed at various time/temperature combinations. When the alloy was annealed 50°C below Tg, the fracture toughness dropped to 6 MPa·m1/2, while DSC and X-ray showed the alloy to still be amorphous. The roughness of the fracture surfaces on relaxed samples also compared well with the relative fracture toughness.