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  • 1
    Digitale Medien
    Digitale Medien
    Degradation of dielectric breakdown field of thermal SiO2 films due to structural defects in Czochralski silicon substrates (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 7944-7957 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We used heat treatment to intentionally introduce various structural defects in Czochralski silicon substrates. The type, size, and number density of the induced defects were surveyed with transmission electron microscopy, and the defects were then incorporated into SiO2 films (10–50 nm thick) during thermal oxidation in dry O2. The effect of the defects on dielectric strength of the SiO2 films was examined with a time zero dielectric breakdown method. Larger platelet oxygen precipitates caused greater decreases of the breakdown field, and precipitates smaller than the SiO2 film thickness did not appreciably reduce the breakdown field. Every large platelet oxygen precipitate incorporated in the SiO2 film caused a degradation. Octahedral oxygen precipitates caused little degradation. The breakdown field was higher than 7 MV/cm and did not depend much on the SiO2 film thickness and precipitate size. We discussed possible mechanisms for the degradation due to both kinds of precipitates. Oxidation-induced stacking faults formed by a surface oxidation did not markedly reduce the breakdown field when only segments of dislocations and stacking faults were incorporated in the SiO2 film. Another serious degradation was caused by pits that were formed by dissolving octahedral oxygen precipitates in a HF solution. The breakdown field was lower for thicker oxide films, and it recovered as the pit shape became smoother during chemical etching. We proposed that this degradation was caused by a local thinning of SiO2 film due to stress generated in the oxidation of pits. These results suggest that voids rather than the other reported grown-in defects play the most important role in the degradation observed for as-grown silicon. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.362344
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  • 2
    Digitale Medien
    Digitale Medien
    Terahertz radiation from superconducting YBa2Cu3O7−δ thin films excited by femtosecond optical pulses (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 2122-2124 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Ultrashort electromagnetic waves (600 fs width) from superconducting YBCO thin films have been observed by irradiating current-biased samples with femtosecond optical laser pulses (80 fs width). The Fourier component of the pulse extends up to ∼2 THz. The characteristics of the radiation are studied and the radiation mechanism is ascribed to the ultrafast supercurrent modulation by the laser pulses, which induce the nonequilibrium superconductivity. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.117175
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  • 3
    Digitale Medien
    Digitale Medien
    Mechanism of crack path morphology and branching from small fatigue cracks under mixed loading (2005)
    PO Box 1354, 9600 Garsington Road, Oxford OX4 2XG, UK. : Blackwell Science Ltd
    Fatigue & fracture of engineering materials & structures 28 (2005), S. 0 
    Details
    ISSN: 1460-2695
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau
    Notizen: In order to investigate the crack path in materials containing a small crack under mixed mode loading, reversed torsion and combined push–pull/torsion fatigue tests were carried out on 0.47% carbon steel specimens containing an initial small crack. The initial small cracks were introduced by a preliminary push–pull fatigue test using a specimen that contained an artificial small hole of 40 μm diameter/depth. Push–pull fatigue tests followed by reversed torsion, and reversed torsion followed by push–pull were carried out. Fatigue tests of combined push–pull/torsion followed by push–pull were also carried out to examine the effect of crack geometry, such as branching and kinking, on cumulative fatigue damage. Different crack growth behaviours due to different loading modes and sequences complicatedly influenced the fatigue crack path and eventually the cumulative fatigue damage. Thus, existing fatigue damage theories cannot be applied to the cases presented in this study. A single factory roof morphology was formed on the fracture surface of the specimen having an initial semielliptical surface crack under cyclic torsion. Taking the result into consideration, torsional fatigue tests of circumferentially cracked specimens were carried out to investigate the Mode III crack growth threshold and the formation mechanism of the factory roof. It was found that the factory-roof pattern was formed by Mode I crack branching from small semielliptical cracks nucleated ahead of the circumferential crack tip. Thus, stress intensity factors at the semielliptical crack tip ahead of the circumferential crack tip were analysed to make the mechanism of crack branching from the semielliptical crack clear. The analysis shows that the Mode III stress intensity factor, KIII, at the deepest point of the semielliptical crack decreases with increase in the depth of semielliptical crack. It follows that as the shear crack growth becomes difficult at the semielliptical crack tip, crack branching starts at the major axis ends in the direction for Mode I growth, forming factory roof, due to ΔKIth 〈 ΔKIIIth.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1460-2695.2004.00828.x
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  • 4
    Digitale Medien
    Digitale Medien
    STATISTICAL ANALYSIS OF DEFECTS FOR FATIGUE STRENGTH PREDICTION AND QUALITY CONTROL OF MATERIALS (1998)
    Oxford, UK : Blackwell Science Ltd
    Fatigue & fracture of engineering materials & structures 21 (1998), S. 0 
    Details
    ISSN: 1460-2695
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau
    Notizen: A wide range of studies and experimental evidence have shown that the lower bound of fatigue properties can be correctly predicted by considering the maximum occurring defect size. The estimate of this dimension can be done by analysing the defect sizes using the statistics of extremes.The scope of this paper is to discuss and investigate the two key points in a successful application of this technique: the first is the choice of statistical method for the analysis of data; the second is the knowledge of the minimum number of defects needed to obtain a good estimate of extreme defects.The results obtained in this study allow one to formulate a procedure for estimating the extreme defects with a precision suitable for fatigue strength prediction.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1460-2695.1998.00104.x
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  • 5
    Digitale Medien
    Digitale Medien
    A NEW METHOD FOR THE MEASUREMENT OF MODE II FATIGUE THRESHOLD STRESS INTENSITY FACTOR RANGE ΔKτth (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 20 (1997), S. 0 
    Details
    ISSN: 1460-2695
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Maschinenbau
    Notizen: Abstract— In order to evaluate the threshold value ΔKτth for mode II fatigue crack growth, a new measurement method of mode II fatigue crack growth has been developed. This method uses a conventional closed-loop tension—compression fatigue testing machine without additional loading attachments. Mode II fatigue tests for structural steel and rail steel have been carried out. This method has proved successful and has reproduced mode II fatigue fracture surfaces similar to those found in the spalling of industrial steel-making rolls. The crack length during testing was measured by an AC potential method. The relationships between da/dN and ΔKτ and AKτth for several materials have been obtained.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1460-2695.1997.tb01530.x
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  • 6
    Digitale Medien
    Digitale Medien
    Simultaneous determination of chlorine and oxygen evolving at RuO2/Ti and RuO2–TiO2/Ti anodes by differential electrochemical mass spectroscopy (1998)
    Springer
    Journal of applied electrochemistry 28 (1998), S. 511-516 
    Details
    ISSN: 1572-8838
    Schlagwort(e): ruthenium oxide ; titanium oxide ; chlorine ; oxygen ; DEMS ; porous electrode
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract Chlorine and oxygen evolving at RuO2/Ti and RuO2–TiO2/Ti anodes have been simultaneously determined at electrode potentials from 1.0 to about 2V (vs Ag/AgCl) by differential electrochemical mass spectroscopy (DEMS). On the RuO2/Ti anodes, the threshold electrode potential for oxygen evolution increased with a decrease in RuO2 loading, while the chlorine evolution potential was unchanged. Low RuO2 loading anodes gave a high chlorine evolution ratio under various constant electrolysis potentials. On the RuO2–TiO2/Ti anodes, the threshold electrode potential for oxygen evolution increased with an increase in the TiO2 content more remarkably than that for chlorine evolution. High TiO2 content anodes gave a high chlorine evolution ratio at various constant electrolysis potentials. The combination of RuO2 and TiO2 exhibits a remarkable effect with respect to the enhancement of chlorine evolution selectivity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1003269228566
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  • 7
    Digitale Medien
    Digitale Medien
    Small Defects and Inhomogeneities in Fatigue Strength: Experiments, Models and Statistical Implications (1999)
    Springer
    Extremes 2 (1999), S. 123-147 
    Details
    ISSN: 1572-915X
    Schlagwort(e): Fatigue limit ; maximum defect ; projection area ; inclusion ; extremes ; Gumbel ; 62N05 ; 60D05
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract The method explained in this paper for quantitative evaluation of fatigue limit for materials containing defects is based on the experimental evidences that inhomogeneities and micro-notches can be treated like cracks. First, the basic concept of the √area parameter model is explained introducing the various data obtained by the first author's group for over last 15 years. Evidences are shown that small cracks, defects and nonmetallic inclusions having the same value of the square root of projection area, √area, have the identical influence on the fatigue limit regardless of different stress concentration factors. Various applications of these concepts to various defect types and microstructural inhomogeneities are shown. Since the estimation of fatigue strength is related to the estimation of the size of maximum defects occurring in a piece, the methods for searching the defects and the quality control of materials with respect to inclusion or defect rating as well as their statistical implications are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1009976418553
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  • 8
    Digitale Medien
    Digitale Medien
    Low-temperature selective reduction of NO with propene over alkaline-exchanged mordenites (1997)
    Springer
    Catalysis letters 45 (1997), S. 267-269 
    Details
    ISSN: 1572-879X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Partially protonated alkaline mordenites showed higher activity per acid amount below 573 K than acidic zeolites for the selective reduction of NO with C3H6 in the presence of O2, which can be related to a high concentration of NO3 - species in the zeolite channels.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1019084116328
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  • 9
    Digitale Medien
    Digitale Medien
    Evaluation of an automated DNA sequencing system developed in RIKEN (1995)
    Springer
    Bioprocess and biosystems engineering 13 (1995), S. 223-229 
    Details
    ISSN: 1432-0797
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Abstract For the advancement of Human Genome Project, we have developed an automated DNA sequencing system ‘HUGA-I.’ It is composed of several automated instruments and transfer robots connecting them. In this paper we describe the results of the performance evaluation test of HUGA-I. Although some of the system units showed good performances, the total performance of the HUGA-I was about 1/6 of the designed value. By revealing principal reasons of this poor performance, we would like to contribute to the automation in genome analysis, particularly in human genome analysis. Since the sequence technology advanced remarkably in these years, the system units of HUGA-I become older than those which are now commercially available and the throughput of it is out of our expectations. Nevertheless, we believe that it is meaningful to introduce the exact performance of HUGA-I and present the bottle neck points in the automating sequencing processes. Because, automation in the gene analysis is ultimately important, in particular for the analysis of large genomes such as the human genome. The aims of this paper are to introduce the results in performance evaluation of HUGA-I and to elucidate the bottle neck points in the automation of sequencing processes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00417632
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  • 10
    Digitale Medien
    Digitale Medien
    TEM Studies on the Microstructure in Ferromagnetic Shape Memory Alloys (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 47-50 (June 2008), p. 515-518 
    Details
    ISSN: 1662-8985
    Quelle: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Thema: Maschinenbau
    Notizen: The magnetic domain structures of the cubic parent phase (high-temperature phase) inferromagnetic shape memory alloys (SMAs) have been studied by electron holography. In aNi51Fe22Ga17 alloy, the magnetic flux distribution in the parent phase changes dramatically beforethe onset of martensitic transformation. In contrast, a Ni45Co5Mn36.7In13.3 alloy—a recentlydeveloped ferromagnetic SMA—does not show appreciable changes in the magnetic domainstructure upon cooling. The anomaly observed in the Ni51Fe22Ga17 alloy appears to be due tolattice distortions, which become more pronounced as the temperature approaches the martensitictransformation start temperature, Ms
    Materialart: Digitale Medien
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/40/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.47-50.515.pdf
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