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2005

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Articles 2011 - 2040 of 3074

Full-Text Articles in Engineering

Transform Based And Search Aware Text Compression Schemes And Compressed Domain Text Retrieval, Nan Zhang Jan 2005

Transform Based And Search Aware Text Compression Schemes And Compressed Domain Text Retrieval, Nan Zhang

Electronic Theses and Dissertations

In recent times, we have witnessed an unprecedented growth of textual information via the Internet, digital libraries and archival text in many applications. While a good fraction of this information is of transient interest, useful information of archival value will continue to accumulate. We need ways to manage, organize and transport this data from one point to the other on data communications links with limited bandwidth. We must also have means to speedily find the information we need from this huge mass of data. Sometimes, a single site may also contain large collections of data such as a library database, …


Seawinds Radiometer Brightness Temperature Calibration And Validation, Mayank Rastogi Jan 2005

Seawinds Radiometer Brightness Temperature Calibration And Validation, Mayank Rastogi

Electronic Theses and Dissertations

The NASA SeaWinds scatterometer is a radar remote sensor which operates on two satellites; NASA's QuikSCAT launched in June 1999 and on Japan's ADEOS-II satellite launched in December 2002. The purpose of SeaWinds is to provide global measurements of the ocean surface wind vector. On QuikSCAT, a ground data processing algorithm was developed, which allowed the instrument to function as a QuikSCAT Radiometer (QRad) and measure the ocean microwave emissions (brightness temperature, Tb) simultaneously with the backscattered power. When SeaWinds on ADEOS was launched, this same algorithm was applied, but the results were anomalous. The initial SRad brightness temperatures exhibited …


Unified Large And Small Signal Discrete-Space Modeling For Pwm Converters In Ccm, Ehab Hamed Shoubaki Jan 2005

Unified Large And Small Signal Discrete-Space Modeling For Pwm Converters In Ccm, Ehab Hamed Shoubaki

Electronic Theses and Dissertations

In this Thesis a Unified Discrete State-Space Model for power converters in CCM is presented. Two main approaches to arriving at the discrete model are used. The first approach involves an impulse function approximation of the duty cycle modulations of the converter switches , and this approach results in a small signal discrete model. The Second approach is direct and does not involve any approximation of the modulations , this approach yields both a large signal nonlinear discrete model and a linear small signal model. Harmonic analysis of the converter states at steady-state is done for steady-state waveform acquisition , …


Alternative Foam Treatments For The Space Shuttle's External Tank, Kirsten Dreggors Jan 2005

Alternative Foam Treatments For The Space Shuttle's External Tank, Kirsten Dreggors

Electronic Theses and Dissertations

The Space Shuttle Columbia accident and the recent excitement surrounding Discovery's return to space brought excessive media attention to the foam products used on the External Tank (ET). In both cases, videos showed chunks of foam or ablative material falling away from the ET during lift off. This led to several years of investigation and research into the exact cause of the accident and potential solutions to avoid the problem in the future. Several design changes were made prior to the return to flight this year, but the ET still shed foam during lift off. Since the Columbia accident, the …


Background Stabilization And Motion Detection In Launch Pad Video Monitoring, Kaushik Gopalan Jan 2005

Background Stabilization And Motion Detection In Launch Pad Video Monitoring, Kaushik Gopalan

Electronic Theses and Dissertations

Automatic detection of moving objects in video sequences is a widely researched topic with application in surveillance operations. Methods based on background cancellation by frame differencing are extremely common. However this process becomes much more complicated when the background is not completely stable due to camera motion. This thesis considers a space application where surveillance cameras around a shuttle launch site are used to detect any debris from the shuttle. The ground shake due to the impact of the launch causes the background to be shaky. We stabilize the background by translation of each frame, the optimum translation being determined …


Slope Stability Of Laterite Soil Embankments, Ikiensinma Gogo-Abite Jan 2005

Slope Stability Of Laterite Soil Embankments, Ikiensinma Gogo-Abite

Electronic Theses and Dissertations

Embankments are key elements in the infrastructural development of structures such as dams, bridges, and roads. Residual soils are generally used as fills in the construction of embankments in areas were residual soils such as laterite is the dominant soil types. Laterite soils have the characteristics of losing its shear strength with time and in fully saturated conditions and its properties varies from region to region. The soil property is influenced by the chemical composition and the environment. The binding agent iron oxide in such soils changes its composition with time and in the presence of moisture. Sudden failures of …


Investigations On Rf Sputter Deposited Sicn Thin Films For Mems Applications, Ravi Todi Jan 2005

Investigations On Rf Sputter Deposited Sicn Thin Films For Mems Applications, Ravi Todi

Electronic Theses and Dissertations

With the rapid increase in miniaturization of mechanical components, the need for a hard, protective coatings is of great importance. In this study we investigate some of the mechanical, chemical and physical properties of the SiCN thin films. Thin films of amorphous silicon carbide nitride (a-SiCxNy) were deposited in a RF magnetron sputtering system using a powder pressed SiC target. Films with various compositions were deposited on to silicon substrate by changing the N2/Ar gas ratios during sputtering. Nano-indentation studies were performed to investigate the mechanical properties such as hardness and reduced modulus of the SiCN films. Surface morphology of …


Robot Assisted Ultrasound Imaged Guided Interstitial Lung Brachytherapy In A Porcine Model, Richard A. Malthaner, Edward Yu, Jerry J. Battista, Chris Blake, Donal Downey, Aaron Fenster Jan 2005

Robot Assisted Ultrasound Imaged Guided Interstitial Lung Brachytherapy In A Porcine Model, Richard A. Malthaner, Edward Yu, Jerry J. Battista, Chris Blake, Donal Downey, Aaron Fenster

Oncology Presentations

We set out to see if permanent interstitial brachytherapy seeds could be safely and reproducibly inserted thoracoscopicaly with the ZEUS Robotic system and intraoperative ultrasound into in-vivo porcine lungs.


Application Of The Fuzzy Performance Indices To The City Of London Water Supply System, Ibrahim El-Baroudy, Slobodan P. Simonovic Jan 2005

Application Of The Fuzzy Performance Indices To The City Of London Water Supply System, Ibrahim El-Baroudy, Slobodan P. Simonovic

Water Resources Research Report

This study explores the utility of fuzzy performance indices: (i) combined reliabilityvulnerability index, (ii) robustness index, and (iii) resiliency index, for evaluating the performance of a complex water supply system. Regional water supply system for the City of London is used as the case study. The two main components being investigated in this case study are; (i) the Lake Huron Primary Water Supply System (LHPWSS), and (ii) the Elgin Area Primary Water Supply system (EAPWSS).


Theoretical And Experimental Investigations Of Macro-Bend Losses For Standard Single Mode Fibers, Qian Wang, Gerald Farrell, Thomas Feir Jan 2005

Theoretical And Experimental Investigations Of Macro-Bend Losses For Standard Single Mode Fibers, Qian Wang, Gerald Farrell, Thomas Feir

Articles

Modeling of macro-bend losses for single mode fibers with multiple cladding or coating layers is presented. Macro-bend losses for standard single mode fibers (SMF28) are investigated theoretically and experimentally, showing that the inner primary coating layer of SMF28 has a significant impact on the bend losses and most of the radiation field is absorbed in the inner primary coating layer of SMF28. The agreement between theoretical calculations and experimental measurements suggests that the so-called elastooptical correction in modeling is not required for SMF28.


Trioson: A Graphical User Interface For Pattern Sonification, Charlie Cullen, Eugene Coyle Jan 2005

Trioson: A Graphical User Interface For Pattern Sonification, Charlie Cullen, Eugene Coyle

Conference papers

The TrioSon software allows users to map musical patterns to input data variables via a graphical user interface (GUI). The application is a Java routine designed to take input files of standard Comma Separated Values (CSV) format and output Standard Midi Files (SMF) using the internal Java Sound API. TrioSon renders output Sonifications from input data files for up to 3 user-defined parameters, allocated as bass, chord and melody instruments for the purposes of arrangement. In this manner each parameter concerned is distinguished by its individual instrumental timbre, with the option of rendering any combination of 1 to 3 parameters …


Use Of Advanced Synthesis Tools In Teaching Vlsi Design, Kevin Berwick, Dominic Nardone Jan 2005

Use Of Advanced Synthesis Tools In Teaching Vlsi Design, Kevin Berwick, Dominic Nardone

Articles

No abstract provided.


National Center For Engineering And Technology Education, Christine Hailey, Thomas Erekson, Kurt Becker, Maurice Thomas Jan 2005

National Center For Engineering And Technology Education, Christine Hailey, Thomas Erekson, Kurt Becker, Maurice Thomas

Publications

The article reports that the overall impact of the National Center for Engineering and Technology Education (NCETE) is to strengthen the nation's capacity to deliver effective engineering and technology education in the K-12 schools. Further, it informs that the National Science Foundation established the Centers for Learning and Teaching (CLT) program to address needs in the science, technology, engineering, and mathematics (STEM) workforce. The CLT program has three goals, based upon stated national needs. First, CLT are expected to renew and diversify the cadre of national leaders in STEM education. The CLT includes partners with strengths in engineering and in …


Analysis And Implementation Of Ripple Current Cancellation Technique For Electronic Ballasts, Marius G. Marita Jan 2005

Analysis And Implementation Of Ripple Current Cancellation Technique For Electronic Ballasts, Marius G. Marita

ETD Archive

No abstract provided.


U.S. Army Corps Of Engineers Omaha District Monthly Drought Report, December 2005 Jan 2005

U.S. Army Corps Of Engineers Omaha District Monthly Drought Report, December 2005

United States Army Corps of Engineers, Omaha District

Current Conditions


Drought Outlook


Ft. Peck, Montana


Reservoir Elevation Overview


Water Intake Overview


Access Overview


Noxious Weeds Overview


Cultural Resources Overview


Garrison, North Dakota


Reservoir Elevation Overview


Water Intake Overview


Access Overview


Boat Ramp Information


Noxious Weeds Overview


Cultural Resources Overview


Other Areas of Interest/Concern


Oahe, South Dakota


Reservoir Elevation Overview


Water Intake Overview


Access Overview


Noxious Weeds Overview


Cultural Resources Overview


Mainstem Reservoir Information, Weekly Elevation Comparison 7 NOV 2005 through 28 NOV 2005


Mainstem Reservoir Storage Comparison Water Year 2004 vs. Water Year 2005


Ft. Peck, MT


Garrison, ND


Oahe, SD


U.S. Army Corps Of Engineers Omaha District Monthly Drought Report, October 2005 Jan 2005

U.S. Army Corps Of Engineers Omaha District Monthly Drought Report, October 2005

United States Army Corps of Engineers, Omaha District

Current Conditions


Drought Outlook


Ft. Peck, Montana


Reservoir Elevation Overview


Water Intake Overview


Access Overview


Noxious Weeds Overview


Cultural Resources Overview


Garrison, North Dakota


Reservoir Elevation Overview


Water Intake Overview


Access Overview


Boat Ramp Information


Noxious Weeds Overview


Cultural Resources Overview


Other Areas of Interest/Concern


Oahe, South Dakota


Reservoir Elevation Overview


Water Intake Overview


Access Overview


Noxious Weeds Overview


Cultural Resources Overview


Mainstem Reservoir Information, Weekly Elevation Comparison 27 JUN 2005 through 31AUG 2005


Mainstem Reservoir Storage Comparison Water Year 2004 vs. Water Year 2005


Ft.Peck, MT


Garrison, ND


Oahe,SD


Miniaturized Lead Sensor Based On Lead-Specific Dnazyme In A Nanocapillary Interconnected Microfluidic Device, In-Hyoung Chang, Joseph J. Tulock, Juewen Liu, Won-Suk Kim, Donald M. Cannon, Jr., Yi Lu, Paul W. Bohn, Jonathan V. Sweedler, Donald M. Cropek Jan 2005

Miniaturized Lead Sensor Based On Lead-Specific Dnazyme In A Nanocapillary Interconnected Microfluidic Device, In-Hyoung Chang, Joseph J. Tulock, Juewen Liu, Won-Suk Kim, Donald M. Cannon, Jr., Yi Lu, Paul W. Bohn, Jonathan V. Sweedler, Donald M. Cropek

United States Army: Publications

A miniaturized lead sensor has been developed by combining a lead-specific DNAzyme with a microfabricated device containing a network of microfluidic channels that are fluidically coupled via a nanocapillary array interconnect. A DNAzyme construct, selective for cleavage in the presence of Pb2+ and derivatized with fluorophore (quencher) at the 5’ (3’) end of the substrate and enzyme strands, respectively, forms a molecular beacon that is used as the recognition element. The nanocapillary array membrane interconnect is used to manipulate fluid flows and deliver the small-volume sample to the beacon in a spatially confined detection window where the DNAzyme is …


Food Acceptability In Field Studies With Us Army Men And Women: Relationship With Food Intake And Food Choice After Repeated Exposures, Cees De Graaf, F. Matthew Kramer, Herbert L. Meiselman, Larry L. Lesher, Carol Baker-Fulco, Edward S. Hirsch, John Warber Jan 2005

Food Acceptability In Field Studies With Us Army Men And Women: Relationship With Food Intake And Food Choice After Repeated Exposures, Cees De Graaf, F. Matthew Kramer, Herbert L. Meiselman, Larry L. Lesher, Carol Baker-Fulco, Edward S. Hirsch, John Warber

United States Army: Publications

Laboratory data with single exposures showed that palatability has a positive relationship with food intake. The question addressed in this study is whether this relationship also holds over repeated exposures in non-laboratory contexts in more natural environments. The data were collected in four field studies, lasting 4–11 days with 307 US Army men and 119 Army women, and comprised 5791 main meals and 8831 snacks in total. Acceptability was rated on the nine point hedonic scale, and intake was registered in units of 1/4, 1/2, 3/4, or 1 or more times of the provided portion size. Correlation coefficients between individual …


Brown Recluse Spider Bite To The Face, Daniel C. Madion, Melanie K. Marshall, Christopher D. Jenkins, George M. Kushner Jan 2005

Brown Recluse Spider Bite To The Face, Daniel C. Madion, Melanie K. Marshall, Christopher D. Jenkins, George M. Kushner

United States Army: Publications

Oral and maxillofacial surgeons must be prepared to manage a variety of maxillofacial infections, both odontogenic and non-odontogenic in nature. While odontogenic infections are quite common, non-odontogenic infections can present with diagnostic and therapeutic challenges. An uncommon non-odontogenic infection is the cellulitis secondary to a spider bite.
Few spider species have the ability to bite through human skin. Most of these insults result in only a small, red nodule centered within a larger, erythematous plaque. Symptoms are usually limited to pruritus and perhaps mild tenderness. The brown recluse and the black widow are 2 types of spiders that inhabit the …


Coronary Calcium Independently Predicts Incident Premature Coronary Heart Disease Over Measured Cardiovascular Risk Factors, Allen J. Taylor, Jody Bindeman, Irwin Feuerstein, Felix Cao, Michael Brazaitis, Patrick G. O'Malley Jan 2005

Coronary Calcium Independently Predicts Incident Premature Coronary Heart Disease Over Measured Cardiovascular Risk Factors, Allen J. Taylor, Jody Bindeman, Irwin Feuerstein, Felix Cao, Michael Brazaitis, Patrick G. O'Malley

United States Army: Publications

OBJECTIVES - We sought to examine the independent predictive value of coronary artery calcium detection for coronary outcomes in a non-referred cohort of healthy men and women ages 40 to 50 years.

BACKGROUND - Existing studies have suggested that coronary calcium might have incremental predictive value for coronary outcomes above standard coronary risk factors. However, additional data from non-referred and younger populations are needed.

METHODS - Participants (n = 2,000; mean age 43 years) were evaluated with measured coronary risk variables and coronary calcium detected with electron beam tomography. Incident acute coronary syndromes and sudden cardiac death were ascertained via …


United States Air Force Posture Statement 2005, U.S. Air Force Jan 2005

United States Air Force Posture Statement 2005, U.S. Air Force

United States Air Force: Publications

Today's security environment is characterized by change and ambiguity. The future will include a variety of challenges, including the risk of catastrophic attacks on the homeland and possibly of disruptive technological breakthroughs by our adversaries.


Sample Preparation And Characterization Of Artificially Aged Aircraft Coatings For Microstructural Analysis, Lisa M. Farrier, Stephen A. Szaruga Jan 2005

Sample Preparation And Characterization Of Artificially Aged Aircraft Coatings For Microstructural Analysis, Lisa M. Farrier, Stephen A. Szaruga

United States Air Force: Publications

The paper describes a method for metallographic preparation of artificially aged aircraft coatings. In order to better understand the in-service performance and identify degradation mechanisms of an aircraft coating, complete characterization of the microstructure is essential. This paper discusses metallographic sample preparation and subsequent microscopy techniques (light optical microscopy, scanning electron microscopy) for characterization of a standard polyurethane aircraft coating system. The preparation method has proven to produce good, consistent results on a wide range of laboratory-produced simulated environmental exposures.

The military specification coating system under study (MIL-PRF-85285C and MIL-PRF-23377G) degrades severely after accelerated weathering. Typical degradation includes deterioration of …


Improving Pilot Mental Workload Classification Through Feature Exploitation And Combination: A Feasibility Study, Jeremy B. Noel, Kenneth W. Bauer, Jr., Jeffrey W. Lanning Jan 2005

Improving Pilot Mental Workload Classification Through Feature Exploitation And Combination: A Feasibility Study, Jeremy B. Noel, Kenneth W. Bauer, Jr., Jeffrey W. Lanning

United States Air Force: Publications

Predicting high pilot mental workload is important to the United States Air Force because lives and aircraft have been lost due to errors made during periods of flight associated with mental overload and task saturation. Current research efforts use psychophysiological measures such as electroencephalography (EEG), cardiac, ocular, and respiration measures in an attempt to identify and predict mental workload levels. Existing classification methods successfully classify pilot mental workload using flight data for a single pilot on a given day, but are unsuccessful across different pilots and/or days. We demonstrate a small subset of combined and calibrated psychophysiological features collected from …


Using Multi-Stack And Variable-Speed-Drive Systems To Reduce Laboratory Exhaust Fan Energy, Gang Wang, Mingsheng Liu Jan 2005

Using Multi-Stack And Variable-Speed-Drive Systems To Reduce Laboratory Exhaust Fan Energy, Gang Wang, Mingsheng Liu

Durham School of Architectural Engineering and Construction: Faculty Publications

In buildings that contain laboratories, fume hoods are normally used to control contaminant concentrations. Exhaust stacks with a constant exit velocity are required to make sure that dangerous concentrations do not occur in occupied areas near the building or on the roof top. To achieve constant velocity when exhaust flow rates are less than design, makeup air is introduced to the system at the inlet of the exhaust fan. Since laboratory exhaust airflow is often significantly less than the design airflow, exhaust fans consume significantly more energy than is necessary. To reduce exhaust fan energy, techniques involving multiple exhaust stacks …


Role Of Branching On The Structure Of Polymer Brushes Formed From Comb Copolymers, Peng Tian, David Uhrig, Jimmy W. Mays, Hiroshi Watanabe, S. Michael Kilbey, Ii Jan 2005

Role Of Branching On The Structure Of Polymer Brushes Formed From Comb Copolymers, Peng Tian, David Uhrig, Jimmy W. Mays, Hiroshi Watanabe, S. Michael Kilbey, Ii

United States Department of Energy: Publications

The distinguishing feature of a polymer brush at equilibrium is the stretched configuration of the chains that results from tethering the polymer chains by one end at the solid-fluid interface. The stretched configuration of the chains and the crowded nature of the interfacial layer is the origin of many of the useful properties of polymer brushes: these layers resist compression and aggregation, effectively dissipate shear stresses, and respond reversibly to changes in their solution environment.


Maldi-Tof Ms Characterization Of Carboxyl-End-Capped Polystyrenes Synthesized Using Anionic Polymerization, Haining Ji, William K. Nonidez, Rigoberto C. Advincula, Grant D. Smith, S. Michael Kilbey Ii, Mark D. Dadmun, Jimmy W. Mays Jan 2005

Maldi-Tof Ms Characterization Of Carboxyl-End-Capped Polystyrenes Synthesized Using Anionic Polymerization, Haining Ji, William K. Nonidez, Rigoberto C. Advincula, Grant D. Smith, S. Michael Kilbey Ii, Mark D. Dadmun, Jimmy W. Mays

United States Department of Energy: Publications

A comparative study of three strategies used to synthesize well-defined carboxyl-end-capped polystyrenes is reported. Structural characterization was carried out using a combination of thin-layer chromatography (TLC) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). For the reaction of polystyryl anions with 4-bromo-1,1,1-trimethoxybutane, in addition to the major product, Bu-PS-CH2CH2CH2COOH, four byproducts were observed. Their mass values suggest the following structures: Bu-PS-H, Bu-PS-CH3, Bu-PS-CH2CH=CH-CHO, and Bu-PS-CH2CH2CH2- CO-PS-Bu. The reaction of polystyryl anions with succinic anhydride generated the targeted compound, Bu-PS-CO-CH2CH2COOH, …


Ferrous Hydroxy Carbonate Is A Stable Transformation Product Of Biogenic Magnetite, Ravi K. Kukkadapu, John M. Zachara, James K. Fredrickson, David W. Kennedy, Alice C. Dohnalkova, David E. Mccready Jan 2005

Ferrous Hydroxy Carbonate Is A Stable Transformation Product Of Biogenic Magnetite, Ravi K. Kukkadapu, John M. Zachara, James K. Fredrickson, David W. Kennedy, Alice C. Dohnalkova, David E. Mccready

United States Department of Energy: Publications

An ~1:1 mixture of ferrihydrite and nanocrystalline akaganeite (β-FeOOH; 10–15 nm) was incubated with Shewanella putrefaciens (strain CN32) under anoxic conditions with lactate as an electron donor and anthraquinone-2,6-disulfonate (AQDS) as an electron shuttle. The incubation was carried out in a 1,4-piperazinediethanesulfonic acid (PIPES)-buffered medium, without PO34– at circumneutral pH. Iron reduction was measured as a function of time (as determined by 0.5 N HCl extraction), and solids were characterized by X-ray diffraction (XRD), electron microscopy, and Mössbauer spectroscopy. The biogenic reduction of Fe3+was rapid; with 60% of the total Fe (FeTOT) reduced …


Control Of Fe(Iii) Site Occupancy On The Rate And Extent Of Microbial Reduction Of Fe(Iii) In Nontronite, Deb P. Jaisi, Ravi K. Kukkadapu, Dennis D. Eberl, Hailiang Dong Jan 2005

Control Of Fe(Iii) Site Occupancy On The Rate And Extent Of Microbial Reduction Of Fe(Iii) In Nontronite, Deb P. Jaisi, Ravi K. Kukkadapu, Dennis D. Eberl, Hailiang Dong

United States Department of Energy: Publications

A quantitative study was performed to understand how Fe(III) site occupancy controls Fe(III) bioreduction in nontronite by Shewanella putrefaciens CN32. NAu-1 and NAu-2 were nontronites and contained Fe(III) in different structural sites with 16 and 23% total iron (w/w), respectively, with almost all iron as Fe(III). Mössbauer spectroscopy showed that Fe(III) was present in the octahedral site in NAu-1 (with a small amount of goethite), but in both the tetrahedral and the octahedral sites in NAu-2. Mössbauer data further showed that the octahedral Fe(III) in NAu-2 existed in at least two environments- trans (M1) and cis (M2) sites. The microbial …


Effects Of Sediment Iron Mineral Composition On Microbially Mediated Changes In Divalent Metal Speciation: Importance Of Ferrihydrite, D. Craig Cooper, Andrew L. Neal, Ravi K. Kukkadapu, Dale Brewe, Aaron Coby, Flynn W. Picardal Jan 2005

Effects Of Sediment Iron Mineral Composition On Microbially Mediated Changes In Divalent Metal Speciation: Importance Of Ferrihydrite, D. Craig Cooper, Andrew L. Neal, Ravi K. Kukkadapu, Dale Brewe, Aaron Coby, Flynn W. Picardal

United States Department of Energy: Publications

Dissimilatory metal reducing bacteria (DMRB) can influence geochemical processes that affect the speciation and mobility of metallic contaminants within natural environments. Most investigations into the effect of DMRB on sediment geochemistry utilize various synthetic oxides as the FeIII source (e.g., ferrihydrite, goethite, hematite). These synthetic materials do not represent the mineralogical composition of natural systems, and do not account for the effect of sediment mineral composition on microbially mediated processes. Our experiments with a DMRB (Shewanella putrefaciens 200) and a divalent metal (ZnII) indicate that, while complexity in sediment mineral composition may not strongly impact the …


Development Of High-Temperature Ferromagnetism In Sno2 And Paramagnetism In Sno By Fe Doping, A. Punnoose, J. Hays, A. Thurber, M. H. Engelhard, Ravi K. Kukkadapu, C. Wang, V. Shutthanandan, S. Thevuthasan Jan 2005

Development Of High-Temperature Ferromagnetism In Sno2 And Paramagnetism In Sno By Fe Doping, A. Punnoose, J. Hays, A. Thurber, M. H. Engelhard, Ravi K. Kukkadapu, C. Wang, V. Shutthanandan, S. Thevuthasan

United States Department of Energy: Publications

We report the development of room-temperature ferromagnetism in chemically synthesized powder samples of Sn1−xFexO2 (0.005≤ x ≤0.05) and paramagnetic behavior in an identically synthesized set of Sn1−xFexO. The ferromagnetic Sn0.99Fe0.01O2 showed a Curie temperature TC=850 K, which is among the highest reported for transition-metal-doped semiconductor oxides. With increasing Fe doping, the lattice parameters of SnO2 decreased and the saturation magnetization increased, suggesting a strong structure-magnetic property relationship. When the Sn0.95Fe0.05O2 was prepared at different temperatures between …