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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physics Letters A 184 (1994), S. 487-494 
    ISSN: 0375-9601
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0630
    Keywords: 72.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Deep-level transient spectroscopy and thermally stimulated capacitance measurements were used to investigate the properties of deep traps in Si-dopedn-Al x Ga1−xAl layers grown by molecular beam epitaxy. Two electron traps at electron emission activation energies of 0.44 and 0.57 eV have been detected. Both traps were studied in detail and found to be the origin of the persistent-photo-conductivity phenomenon in this material. The nature of both traps is the same as of the DX center in liquid phase epitaxial material reported by Lang et al. The electron capture cross-sections areσ n 1 =σ n 2=8.3×10−22cm2 atT=205K. Activation energies ofE σ 1= 0.33eV andE σ 2=0.37eV at temperatures higher than 125 K were determined by DLTS measurements and by direct measurements of the capture transient. In order to allow for the variation of the free-electron concentration during the capture process, a new method for the evaluation of the electron capture crosssection was developed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 3113-3114 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An infrared radiation pyrometer for transient temperature measurement and a photoelectric installation for micrometric length-change measurement were developed. After being heated by a CO2 laser pulse of 0.1 μs, the transient temperature-rise history and length change of thermal expansion of 20–50 μm Al films during tens of microseconds were recorded. Nonsynchronous change of temperature and thermal expansion under transient heating was observed.
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  • 4
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The introduction of small amounts of Dy in ceramic BiSrCaCuO (BSCCO) with nominal composition of Bi2Sr2Ca1−xDyxCu2O8+z, Bi2Sr2Ca2−xDyxCu3O10+z, and Bi1.6Pb0.4Sr2Ca2−xDyxCu3O10+z with 0.1〈x〈0.3 was studied in both stoichiometric and nonstoichiometric compositions where the nonstoichiometric composition was used to aid the sintering process in order to obtain a maximum Tc and contained excesses of CaO and CuO. It was found that regardless of the sintering conditions and starting compositions only the Bi:Sr:Ca:Cu=2:2:1:2 (2212) phase was produced. The highest Tc (R=0) in the Dy-substituted sample obtained was 84 K and this was obtained only for the nonstoichiometric composition Bi1.6Pb0.4Sr2Ca2.5Dy0.3Cu3.5Ox which contained mostly the 2212 phase together with tiny amounts of Bi2Sr2Ca2Cu3Ox (2223) phase. High-resolution electron microscopy data performed on Bi1.6Pb0.4Sr2Ca2.5Dy0.3Cu3.5010+z show that the introduction of Dy in the original 2223 Pb-containing phase caused only the formation of the 2212 phase without changing the modulated structure known to occur in the substituted Bi and Sr BSCCO compounds confirming also earlier suggestions made by Tarrascon et al. [Phys. Rev. B 2, 4316 (1989)] that the rare-earth cations stabilize the 2212 phase and substitute only for Ca and not for the Sr or Bi sites in the 2212 phase.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The effect of in vitro induction of calcium phosphate on bamboo surfaces is reported for the first time. Bamboo is studied for biomaterial application due to its elasticity modulus being closer to human bone than other biomaterials. Following an earlier study of cytotoxicity and precipitation of apatite on ground tissue and vascular bundles of bamboo, the composition and function of the minerals in bamboo, especially silica, are considered in the present work. It is found that in both outer and inner surfaces of bamboo culm, there exists some silica. Bamboo elicits an inert response when soaked directly in calcification solution. After the rind of bamboo is treated with sodium hydroxide solution, the silica underneath can induce precipitation of calcium phosphate in an ambient environment. Furthermore, by subsequent grafting with polyethylene glycol (PEG 1000), calcium phosphate induction of bamboo rind can be improved, depending on the concentration of NaOH solution and treatment time. Heat treatment of bamboo can remove the organic materials around the minerals in bamboo, allowing the calcification behaviour of the silica-containing inorganic phase of bamboo in aqueous solution to be studied.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1572-9567
    Keywords: diamond ; film ; flash method ; thermal diffusivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This paper discusses the short-pulse-flash method developed for thermal diffusivity measurements on thin films. Two kinds of CVD diamond film have been prepared, and their thermal diffusivity in the perpendicular direction has been measured with this method. The measurement errors caused by the surface coating are discussed.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1572-9605
    Keywords: Submillimeter wave ; laser ; reflection ; surface resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Submillimeter wave laser reflection measurements of surface resistance can provide improved capability in the combination of sensitivity, spatial resolution, and frequency range. We have made reflectivity measurements on metals at 1630 GHz with an uncertainty of less than 0.3%. This sensitivity corresponds to a measurement sensitivity for surface resistance of 0.3 Ω. Assuming anf 2 frequency scaling of high-temperature superconductor surface resistance from the microwave to the terahertz frequency range, this sensitivity corresponds to about 1 ×10−5 Ω at 10 GHz. Capability for 10−7 Ω sensitivity could eventually be possible. Preliminary submillimeter wave reflection measurements of a YBCO thin film have been made with a sensitivity of 1%. Submillimeter wave reflectometry can make it possible to determine the spatial dependence of surface resistance in a wide range of material sizes and shapes. The spatial resolution could be on the order of 0.3–0.5 mm.
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  • 8
    ISSN: 1572-9567
    Keywords: composites ; copper ; flash method ; iron ; thermal diffusivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A method for measuring thermal diffusivity in one of the layers of a two-layer composite sample has been described. The heat transfer problem of a two-layer sample associated with pulse thermal diffusivity measurements has been analyzed for two cases: exponential and square-wave pulses. According to our measurements, a triangular heat-pulse function approximates reasonably well the output of the Nd-glass laser. In this paper, an expression is derived for the temperature transient at the rear face of two-layer sample being subjected to a triangular heat-pulse input on the front face. The analytical solution of the problem forms the basis of our method of data reduction. This solution has been programmed for computer processing of the data. The method described here has been successfully tested by limited measurements on copper and iron.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1572-9567
    Keywords: specific heat ; thermal conductivity ; thermal diffusivity ; thermal emissivity ; thermophysical properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Various aspects of the importance of thermophysical property (TPP) studies to science and technology in China are discussed. Several stages of the development of experimental principles and equipment are described. Some examples of TPP applications in economic practice are presented. Theoretical and methodological studies in this field are summarized. The presentations are limited mostly to work on solids.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1572-9567
    Keywords: anisotropic materials ; pyrolytic graphite ; pyrolytic boron nitride ; thermal conductivity ; thermal diffusivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The laser pulse method can be successfully applied to the measurement of thermal diffusivity of isotropic materials subject to some assumptions. For anisotropic materials, this method is applicable to the measurement of principal thermal diffusivity only on the condition that there is no difference in direction between the principal axis and that of the temperature gradient. After analyzing the heat conduction process in an anisotropic solid, it has been shown that large errors in the measurement of thermal diffusivity would exist if the direction of the principal axis deviates inconspicuously from that of the temperature gradient. The experimental results of thermal diffusivity of highly oriented pyrolytic graphite (HOPG) samples with various deviation angles have been compared with the analytical results. The laser pulse method is not applicable to measurements on semitransparent pyrolytic boron nitride (PBN). We adopted a two-layer composite sample to measure the thermal diffusivity of PBN in the c direction and a particular graphite-PBN composite sample has been prepared which has a very low thermal resistance at the interface. The thermal diffusivity and thermal conductivity of PG (below 2300°C) and PBN (below 1000°C) are given.
    Type of Medium: Electronic Resource
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