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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 7944-7957 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1912-1917 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This paper describes how a small helium (4He) peak can be separated from a large adjacent deuterium (D2) peak using a modified quadrupole mass spectrometer (QMS). This QMS utilized a condition of the second stability zone (zone II) in the Mathieu diagram. The minimum detectable peak ratio of 4He to D2 was 10−4 when a mass scan line was set close to the upper tip, and was 10−3 when the scan line was adjusted to the lower tip. The ion transmission rates simulating the peaks were calculated for the upper and lower zone conditions. It was found that a longer peak tail occurs when an unstable orbit has mainly a cosh function. From the experimental and theoretical data, it is concluded that the upper zone condition is the most suitable for realizing a high-resolution peak.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 303-305 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We examine the effect of bulk microdefects (BMD) intentionally introduced in Czochralski silicon substrates by heat treatment on the dielectric breakdown of thermally grown SiO2 films. Transmission electron microscope observations reveal that the BMD consist of oxygen precipitates, perfect dislocation loops, and faulted dislocation loops. When the BMD are incorporated into the SiO2 film during thermal oxidation, an apparent decrease in the breakdown field is observed. The size of the oxygen precipitates has a clear relationship with the breakdown field: larger oxygen precipitate causes greater degradation. The dislocation loops are unrelated to the breakdown field.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 2122-2124 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Fatigue & fracture of engineering materials & structures 21 (1998), S. 0 
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 20 (1997), S. 0 
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1572-8838
    Keywords: ruthenium oxide ; titanium oxide ; chlorine ; oxygen ; DEMS ; porous electrode
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Extremes 2 (1999), S. 123-147 
    ISSN: 1572-915X
    Keywords: Fatigue limit ; maximum defect ; projection area ; inclusion ; extremes ; Gumbel ; 62N05 ; 60D05
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1572-879X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-1998
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Neuroimaging observations of three infants with congenital rubella syndrome are reported. We have observed congenital rubella syndrome lesions in the subependymal area, the basal ganglia and the deep white matter. Cranial ultrasonography defines subependymal cysts, calcification and possible vascular changes in the basal ganglia while MRI is the most sensitive to minor atrophic changes and white matter lesions. Although CT defines calcification, it is less sensitive than MRI to white matter changes and does not demonstrate subependymal cysts.
    Type of Medium: Electronic Resource
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