bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of Nucleation on the Growth of Nanocrystalline Diamond (NCD) Films: A Particular Study in the Fabrication of Micro-cantilevers
Authors: Jeedigunta Sathyaharish , Spagnol Priscila , Bumgarner John , Kumar Ashok 
Published: April 2011

AbstractThe effect of ultrasonic method of seeding on the growth of nanocrystalline diamond (NCD) films has been studied by investigating the nucleation densities of two nanodiamond slurries- 1) nanodiamond powder suspended in acetone 2) mixture of titanium nanopowder and nanodiamond powder suspended in acetone. The former has resulted in a lower nucleation density on the order of 108 cm−2 while the later has increased the nucleation density by over two orders (>1010 cm−2) of magnitude. NCD films were grown on Si(100) substrates in a Cyrannus I Iplas microwave plasma enhanced chemical vapor deposition (MPECVD) reactor using 0.5% CH4, 1% H2 and 98.5% Ar gas chemistry at a substrate temperature of ∼ 750°C, pressure of 135 T and a microwave power of 1.8 kW. The double anchored cantilever structures with NCD as structural material have been fabricated by conventional photolithography. It was observed that the films grown after pre-treating the substrates in pure nanodiamond slurry have not provided a complete coverage at the anchor regions of the cantilevers due to the lower nucleation density. Hence during the sacrificial oxide etch, the anchor regions did not adhere well to the substrate and the entire structures got detached from the substrate. But on the other hand, the films grown by seeding the substrates in a suspension of titanium nanopowder and diamond nanopowder showed complete film coverage and consequently very good bonding to the Si substrate at the anchor pads. In this case, the cantilevers have been successfully released without any problems at the anchor pads. Further the mechanical properties of the films were conducted by evaluating the Young's modulus and the hardness by nano-indentation technique.
Key Projections on Future PV Performance, Market Penetration and Costs, with Special Reference to CdTe and Other Thin Film Technologies
Authors: Raugei Marco , Frankl Paolo 
Published: April 2011

AbstractThe authors have drafted three alternative scenarios for the technological improvement and market penetration of photovoltaics in the next four decades, based on the preliminary results of the EU FP6 Integrated Project NEEDS, Research Stream 1a. The long-term diffusion of PV is foreseen to depend on the achievable module efficiencies and on the maturity of the different technologies in terms of their manufacturing costs, energy pay-back times, additional BOS costs, and even raw material reserves. Last but not least, the co-evolution of a suitable energy storage network (e.g. hydrogen) is also foreseen to be a mandatory requirement. Cumulative installed capacity worldwide is projected to reach 9,000 GWp in 2050 in the most optimistic scenario, which is reduced to 2,400 GWp in the intermediate scenario. In the third “pessimistic” scenario the current economic incentives are not assumed to be sustained long enough to allow PV to become competitive with bulk electricity, resulting in a stunted market growth (500 GWp in 2050). The resulting predictions in terms of costs range from 0.50 to 1.50 €/Wp in 2050, respectively corresponding to 2 - 8 €-cents per kWh in Southern Europe and 4 - 14 €-cents per kWh in Northern Europe. Within the framework of these three general scenarios, special attention is then put to the role that is likely to be played by thin film technologies, namely amorphous Si, CdTe and CIS/CIGS. These technologies are expected to collectively reach a market share of approximately 45% by as early as 2025 in all but the most pessimistic scenario, wherein the same goal is put off until 2050. Marked increases in module efficiencies and material and energy consumption are also expected, to varying degrees depending on the assumptions made in the three scenarios.
Nano-Structured Materials to Address Challenges of the Hydrogen Initiative
Authors: Berube Vincent , Dresselhaus Mildred 
Published: April 2011

AbstractSince the publication of the 2003 report on Basic Energy Needs for the Hydrogen Economy, many important advances in hydrogen research have occurred, a cadre of enthusiastic researchers has entered the field with great interest shown by students, and private industry has made significant commitment to this technology and investment in its development worldwide. Concurrently, other energy technologies have made major strides forward. These technologies must be evaluated for their scalability, usability, cost and life cycle footprint on the environment. This overview discusses these topics and looks toward the role for the hydrogen economy into our energy future.
Metal Hydrides for Hydrogen Storage
Authors: Graetz Jason , Reilly James J , Wegrzyn James 
Published: April 2011

AbstractThe emergence of a Hydrogen Economy will require the development of new media capable of safely storing hydrogen with high gravimetric and volumetric densities. Metal hydrides and complex metal hydrides, where hydrogen is chemically bonded to the metal atoms in the bulk, offer some hope of overcoming the challenges associated with hydrogen storage. Many of the more promising hydrogen materials are tailored to meet the unique demands of a low temperature automotive fuel cell and are therefore either entirely new (e.g. in structural or chemical composition) or in some new form (e.g. morphology, crystallite size, catalysts). This proceeding presents an overview of some of the challenges associated with metal hydride hydrogen storage and a few new approaches being investigated to address these challenges.
Science and Prospects of Using Nanoporous Materials for Energy Absorption
Authors: Chen Xi , Qiao Yu 
Published: April 2011

AbstractWith its ultra-large specific surface area, a nanoporous material is an ideal, yet relatively unexplored, platform for accepting or actuating liquids, with potential performance gains for energy dissipation and output typical of disruptive technologies. Our experimental and theoretical results indicate either dramatically improved performance or unique combinations of properties and capabilities not attainable in conventional materials, which make the novel nanoporous structures studied herein very attractive as advanced protective intelligent systems.
Effect of Water Vapor and SOx in Air on the Cathodes of Solid Oxide Fuel Cells
Authors: Kim Seon Hye , Ohshima Toshihiro , Shiratori Yusuke , Itoh Kohei , Sasaki Kazunari 
Published: April 2011

AbstractAmbient air is used as an oxygen source in SOFCs to be commercialized. Various chemical species which can lead to poisoning of SOFC cathodes are included as minor constitutions in air, such as water vapor, SOx, NOx and NaCl etc. However, their effects on the cathode performance have not yet well known, even though they are expected to cause a degradation of the electrode performance and to reduce the long-term durability of SOFCs. Therefore, in this study, we focused on the poisoning caused by water vapor and SOx in the oxygen source to clarify their effects on SOFCs performances and to reveal the degradation mechanism of cathodes. SOFCs with typical electrolyte-supported structure were used in this work, which were composed with ScSZ (10 mol% Sc2O3, 1mol% CeO2, 89 mol% ZrO2) plate with the thickness of 200 µm as electrolyte, NiO-ScSZ (mixture of 56 wt% NiO and 44 wt% ScSZ) porous layer as anode, and two cathode layers of LSM ((La0.8Sr0.2)0.98MnO3) and LSM-ScSZ (mixture of 50 wt% LSM and 50 wt% ScSZ). Power generation characteristics of the cells had been analyzed by measuring cell voltage at a constant current density (200 mA/cm2) and by comparing changes in cell impedance, upon supplying the artificially-contaminated air with water vapor or SOx, to the SOFC cathodes at various operational temperatures. High-resolution FESEM (S-5200, Hitachi) was used to analyze microstructural changes caused by the impurities. Mg Kα radiation from a monochromatized X-ray source was used for XPS measurements (ESCA-3400, KRATOS). AC impedance was measured at various temperatures under the open circuit voltage condition by an impedance analyzer (Solatron 1255B/SI 1287, Solatron), in a frequency range from 0.1 to 105 Hz with an amplitude of 10 mV.
Life Cycle Assessment of Future Fossil Technologies with and without Carbon Capture and Storage
Authors: Dones Roberto , Bauer Christian , Heck Thomas , Mayer-Spohn Oliver , Blesl Markus 
Published: April 2011

AbstractThe NEEDS project of the European Commission (2004-2008) continues the ExternE series, aiming at improving and integrating external cost assessment, LCA, and energy-economy modeling, using multi-criteria decision analysis for technology roadmap up to year 2050. The LCA covers power systems suitable for Europe. The paper presents environmental inventories and cumulative results for selected representative evolutionary hard coal and lignite power technologies, namely the Ultra-Supercritical Pulverized Combustion (USC-PC) and Integrated Gasification Combined Cycle (IGCC) technologies. The power units are modeled with and without Carbon Capture and Storage (CCS). The three main technology paths for CO2 capture are represented, namely pre-combustion, post-combustion, and oxy-fuel combustion. Pipeline transport and storage in geological formations like saline aquifers and depleted gas reservoirs, which are the most likely solutions to be implemented in Europe, are modeled for assumed average conditions. The entire energy chains from fuel extraction through, when applicable, the ultimate sequestration of CO2, are assessed, using ecoinvent as background LCA database.The results show that adding CCS to fossil power plants, although resulting in a large net decrease of the CO2 effluents to the atmosphere per unit of electricity, is likely to produce substantially more GHG than claimed by near-zero emission power plant promoters when the entire energy chain is accounted for, especially for post-combustion capture technologies and hard coal as a fuel. Besides, the lower net power plant efficiencies lead to higher consumption rate of non-renewable fossil fuel. Furthermore, consideration of the full spectrum of environmental burdens besides greenhouse gas (GHG) results in a less definite picture of the energy chain with CCS than obtained by just focusing on GHG reduction.
The Fuel Cycles of Electricity Generation: A Comparison of Land Use
Authors: Kim Hyung Chul , Fthenakis Vasilis 
Published: April 2011

AbstractWe investigate the area of land used and/or transformed during conventional (i.e., coal, natural gas and nuclear), and renewable fuel cycles (i.e., photovoltaics, wind, biomass, and geothermal). Both direct and indirect land use/transformation are examined in a life cycle framework. For average US insolation, the photovoltaic fuel cycle disturbs the least amount of land per GWh among renewable options, requiring less area than the coal fuel cycle. Renewable technologies could harvest infinite amount of energy per unit area and eliminates the need for restoring disturbed mine lands. Further investigations would be necessary for secondary and accidental land disturbance by conventional fuel cycles through transport of effluents and emissions to adjacent land.
Hydrogen Degradation Property of Electrochemically Charged Aluminum
Authors: Suzuki Hiroshi , Kobayashi Daisuke , Takai Kenichi , Hagihara Yukito 
Published: April 2011

AbstractDegradation property of aluminum due to hydrogen is studied. Hydrogen is introduced by electrolysis charge in aqueous solution with addition of 0.1 mass % NH4SCN as a hydrogen recombination poison. The amount of hydrogen and its existing state in the material is analyzed by hydrogen desorption curves measured by the thermal desorption spectroscopy. The hydrogen desorption curves of charged aluminum showed two peaks, one at less than 100 °C and the other around 400 °C. The existing state of hydrogen relate to each peaks are identified as weakly trapped solute hydrogen to vacancy and free hydrogen molecule located in cavities that exists in the bulk of the material. Tensile properties are obtained to determine degradation property of the material due to hydrogen. The effect of hydrogen on degradation of charged aluminum is analyzed in terms of interaction between hydrogen and vacancy or dislocation. Solute hydrogen and cavities are found to affect ductility of aluminum, whereas hydrogen molecule in cavities has no effect.
The Stability and Reversibility of TiCl3 Doped LiBH4
Authors: Au Ming , Jurgensen Arthur R , Spenser William A , Anton Donald L , Pinkerton Frederick E 
Published: April 2011

AbstractIn an effort to develop reversible metallic borohydrides with high hydrogen storage capacities and low dehydriding temperature, modifications to LiBH4 with metal halides TiCl3 have been conducted. Adding TiCl3 to LiBH4 effectively reduced the dehydriding temperature through an ion exchange interaction by producing instable transition metal borohydrides and lithium salts. The material LiBH4+0.1TiCl3 desorbed 3.5wt% and 8.5wt% hydrogen at 150°C and 450°C respectively. Subsequent re-absorption of 6wt% hydrogen at 500°C and 70 bars was observed. The XRD analysis of the rehydrided samples confirmed the partial reformation of LiBH4. However, adding more TiCl3 made material more volatile and irreversible. TGA-RGA analyses indicated diborane evolution during dehydrogenation resulting in unrecoverable capacity loss and irreversibility. TiCl3 reduced LiBH4 stability and also made material irreversible.
A New Concept of Hydrogen Storage Using Lithium Hydride and Ammonia
Authors: Kojima Yoshitsugu , Hino Satoshi , Tange Kyoichi , Ichikawa Takayuki 
Published: April 2011

AbstractIt was indicated that H2 is generated by the reaction of LiH and NH3. After H2 generation, the byproduct LiNH2 was recycled back to LiH under H2 flow condition at 500K.
Thermodynamic Modeling of Plutonium Oxide Containing Americium
Authors: Hirota Masayuki , KUROSAKI Ken , UNO Masayoshi , MIWA Shuhei , OSAKA Masahiko , TANAKA Kenya , YAMANAKA Shinsuke 
Published: April 2011

AbstractThermodynamic modeling has been performed for O-Am binary system and O-Pu-Am ternary system on the basis of thermodynamic data available in the literature. The interaction parameters of the excess Gibbs energies of the fluorite structure FCCC1 phase in the O-Am and the O-Pu-Am systems were evaluated with respect to the deviation from the ideal solution in oxygen potential, respectively. The thermodynamic modeling used in this study is based on the CALculation of PHAse Diagram (CALPHAD) technique.
In-situ Formation of Bismuth-Based Iodine Waste Forms
Authors: Nenoff Tina , Krumhansl James L. , Rajan Ashwath 
Published: April 2011

AbstractWe investigated the synthesis of bismuth oxy-iodide and iodate compounds, in an effort to develop materials for iodine recovery from caustic waste streams and/or final waste disposal if repository conditions included ambient conditions similar to those under which the iodine was initially captured. The results presented involve the in-situ crystallization of layered bismuth oxide compounds with aqueous dissolved iodine (which resides as both iodide and iodate in solution). Although single-phase bismuth oxy-iodide materials have already been described in the context of capturing radioiodine, our unique contribution is the discovery that there is a mixture of Bi-O-I compositions, not described in the prior work, which optimize both the uptake and the degree of insolubility (and leachability) of iodine. The optimized combination produces a durable material that is suitable as a waste form for repository conditions such as are predicted at the Yucca Mountain repository (YMP) or in a similar type of repository that could be developed in coordination with iodine production via Global Nuclear Energy Program (GNEP) production cycles.
New Opportunities in Existing Thermoelectric Materials: Grain Boundary Engineering in Pulverized p-Bi2Te3 System
Authors: He Jian , Ji Xiaohua , Su Zhe , Gothard Nick , Edwards Justine , Tritt Terry M. 
Published: April 2011

AbstractGrain boundary scattering provides an effective avenue to lower the thermal conductivity in polycrystalline thermoelectric materials, but it is hard to do this without simultaneously degrading the power factor that is the product of electrical conductivity and thermopower. An immediate question arises as to whether one can fabricate a thermoelectrically favorable grain boundary?In this paper we present a proof-of-principle grain boundary engineering study in the pulverized p-Bi2Te3 system. Utilizing the lately developed hydrothermal nano-coating technique, we fabricated an Alkali-metal(s)-containing surface layer with few tens of nm thick on the p-Bi2Te3 bulk reference grain, where it becomes part of the grain boundary upon hotpressing densification. The electrical resistivity, thermopower, thermal conductivity and Hall coefficient measurements constitute solid evidence that this heterogeneous layer helps decouple the otherwise inter-related resistivity, thermopower and thermal conductivity. To optimize the figure of merit ZT, we carefully varied the ratio between Na, K and Rb concentrations. It was found that the sample treated in the solution with Na/Rb =1:2 achieved a ZT comparable with that of the commercial ingot; in the mean time, the compatibility factor and robustness of device were considerably improved. In principle this technique can be applied to other existing polycrystalline thermoelectric materials as a new “tuning knob”.
NANOCOMPOSITES TO ENHANCE ZT IN THERMOELECTRICS
Authors: Dresselhaus Mildred , Chen Gang , Ren Zhifeng , Fleurial Jean-Pierre , Gogna Pawan , Tang Ming Y , Vashaee Daryoosh , Lee Hohyun , Wang Xiaowei , Joshi Giri , Zhu Gaohua , Wang Dezhi , Blair Richard , Bux Sabah , Kaner Richard 
Published: April 2011

AbstractThe concept of using “self-assembled” and “force-engineered” nanostructures to enhance the thermoelectric figure of merit relative to bulk homogeneous and composite materials is presented in general terms. Specific application is made to the Si-Ge system for use in power generation at high temperature. The scientific advantages of the nanocomposite approach for the simultaneous increase in the power factor and decrease of the thermal conductivity are emphasized along with the practical advantages of having bulk samples for property measurements and a straightforward path to scale-up materials synthesis and integration of nanostructured materials into thermoelectric cooling and power generation devices.
Defect Clustering and Nanostructure Formation in PbTe-based Bulk Thermoelectrics
Authors: Hoang Khang , Mahanti S. D. 
Published: April 2011

AbstractIn recent years, LAST-m (AgPbmSbTem+2) and related materials have emerged as potential high performance high temperature thermoelectrics. One example is LAST-18. When optimally doped, this compound has thermoelectric figure of merit ZT=1.7 at 700K. This large ZT is most likely due to the low lattice thermal conductivity, caused by phonon scattering from nanostructures. These nanostructures involve clustering and ordering of Ag, Sb, and Pb ions. The origin of these nanostructures has been studied using Monte Carlo (MC) simulation of an ionic model and ab initio studies of pair interaction energies. Effects of these substitutions on the band structure near the gap and their implications on transport properties are briefly discussed.
Optimization of High Thermoelectric Figure-of-Merit in p-type Ag1-x(Pb1-ySny)mSb1-zTem+2
Authors: Ahn Kyunghan , Kanatzidis Mercouri G 
Published: April 2011

AbstractThe Ag1-x(Pb1-ySny)mSb1-zTem+2 compounds have been found to exhibit high performance p-type thermoelectric properties and are now being considered for practical applications. In this paper, various m values and silver concentrations were investigated to determine the effect on thermoelectric properties. Also, the charge-compensated compounds were studied in order to eliminate the problem of excess tellurium evaporation at high temperature.
Thermoelectric Properties of Phase Separated Composite of Ln-Doped SrTiO3 and TiO2 Micro Crystals
Authors: Fuda Kiyoshi , Murakami Kenji , Sugiyama Shigeaki 
Published: April 2011

AbstractIt seems that no satisfactory TE property has been found in n-type oxide bulk materials even though Al-doped ZnO and La-doped SrTiO3 have high thermoelectric (TE) responses. Difficulty in developing high-performance TE materials seems to lie in finding low thermal conductivity in such oxides. The purpose of this study is to find a possibility to make an n-type TE oxide bulk material having low thermal conductivity and excellent TE properties as well. For this purpose, we fabricated and examined a series of composites constructed of TiO2 and Ln-doped SrTiO3 fine crystals. The composites were prepared via two processing steps: (1) precursor oxide preparation by wet processes; (2) sintering by using spark plasma sintering (SPS) apparatus. The microscopic structure was examined by using scanning electron microscope (SEM; HITACHI S-4500 model) attached with an energy dispersive x-ray spectroscopy. The electrical conductivities and the Seebeck coefficients were measured simultaneously using an ULVAC ZEM-1 instrument in helium atmosphere. The thermal diffusivities were measured by a laser flash method in vacuum. The composites obtained here were found to commonly have a mosaic type texture constructed of TiO2 and SrTiO3 fine particles with a typical size of 500 nm. The thermal conductivity values measured for three samples with different contents are ranged between 3 and 4 Wm-1K-1 in the temperature range from room temperature to 800 C. The values are apparently lower than the value for single crystal SrTiO3 samples presented in literature. Taking account the other TE data, e.g. Seebeck coefficient and electrical conductivity, we calculated dimensionless figure of merit, ZT, to be at maximum 0.15 at 800°C.
The Effect of Bi Addition on Thermoelectric Properties of the Sintered Heusler Fe2VAl Alloy
Authors: Mikami Masashi , Kobayashi Keizo , Hazumi Kiminori , Nishino Yoichi 
Published: April 2011

AbstractA Fe2VAl0.9Si0.1/Bi composite were fabricated using pulse-current sintering technique with mixed powder prepared by mechanical alloying. Since the raw powders were finely pulverized into nanometer sized crystallite and rapidly sintered to suppress grain growth during heat treatment, microstructural composite was obtained. The composite was consisted of Fe2VAl0.9Si0.1 grains with the size of 200-300 nm and nanometer-sized Bi particles. The size of the Bi particle decreased with the increase in the milling processing time, while the size of the Fe2VAl0.9Si0.1 grains showed no variation. The thermal conductivity of the composite decreased with the reduction of the Bi particle size, because of the increase in the number of hetero junction, at which phonons were scattered. On the contrary, the electrical conductivity was less affected by the incorporation of nanometer-sized Bi particles. This means that the hetero junction between Fe2VAl0.9Si0.1 and Bi has little effect on the carrier traveling or the dispersion of highly conductive Bi particles enhanced electrical conductivity. Although Seebeck coefficient was reduced by a negative effect of Bi incorporation on the Fe2VAl0.9Si0.1 crystal structure, the introduction of Bi nanoinclusions in the sintered Heusler material was effective to reduce the thermal conductivity without degradation of electrical conductivity and consequently improved the thermoelectric figure of merit.