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  • 1
    Electronic Resource
    Electronic Resource
    The interfacial morphology of strained epitaxial InxGa1−xAs/GaAs (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 2224-2230 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The microstructure of strained layers of InxGa1−xAs/GaAs grown by molecular-beam epitaxy has been investigated by transmission electron microscopy. lt was found that the formation of irregular interfacial morphologies of the InxGa1−xAs layers was due to a transition in growth mode from two-dimensional (layer-by-layer growth) to three-dimensional nucleation via island formation. It was also found that the occurrence of irregular growth surfaces of epitaxial layers was dependent upon inhomogeneous lattice strains induced by the formation of islands. A possible role of lattice strain for the formation of irregular growth surfaces was also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348700
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  • 2
    Electronic Resource
    Electronic Resource
    Structure of lattice-strained InxGa1−xAs/GaAs layers studied by transmission electron microscopy (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 1420-1422 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The defect structures of strained InxGa1−xAs/GaAs quantum wells with 0.28≤x≤1.00, which were grown by molecular beam epitaxy on GaAs (001), have been investigated by transmission electron microscopy. It was found that with increasing thicknesses of the layers a transition occurred from homogeneous lattice strain to a "periodic'' inhomogeneous lattice strain. This effect was more pronounced with increasing indium content. For thicker layers, misfit dislocations were created which existed together with the periodic inhomogeneous strain. For even thicker layers, dislocation complexes arose which primarily consisted of intersecting stacking faults.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.99960
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  • 3
    Electronic Resource
    Electronic Resource
    Flow and Failure of Superplastic Materials (1979)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Materials Research 9 (1979), S. 151-189 
    Details
    ISSN: 0084-6600
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.ms.09.080179.001055
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  • 4
    Electronic Resource
    Electronic Resource
    Characterization of individual interfacial barriers in a ZnO varistor material (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 3666-3675 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The role of different types of interfaces in a ZnO varistor material has been investigated by directly measuring the current/voltage characteristics of individual interfacial junctions. The electrically characterized interfaces were subsequently studied by analytical transmission electron microscopy. It was shown that barriers to electrical conduction form during cooling from the sintering temperature. The ZnO/ZnO junctions exhibited breakdowns at either 3.2 or 3.6 V, where the higher breakdown was observed at boundaries which contained a thin (∼2 nm) intergranular amorphous Bi-rich film, while the breakdown at 3.2 V was found at boundaries without secondary phases but which contained intergranularly segregated Bi atoms. Junctions between ZnO and intergranular Bi2O3 exhibited asymmetric current/voltage characteristics with breakdowns at 3.2 V for one polarity of the applied voltage and either 0.4 or 0.9 V for the other polarity. No varistor behavior was observed at interfaces between ZnO and pyrochlore, Zn2Sb3Bi3O14. This gives rise to a significant number of "inactive'' grain boundaries in the material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344453
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  • 5
    Electronic Resource
    Electronic Resource
    Development of interfacial microstructure during cooling of a ZnO varistor material (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 5072-5077 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The development of interfacial microstructure during cooling of a ZnO varistor material from the sintering temperature has been studied by a combination of analytical electron microscopy and x-ray diffractometry. It was found that pyrochlore is the first Bi-rich phase to form from the liquid-phase sintering medium during cooling from the sintering temperature. When cooling at normal rates, pyrochlore forms between 940 and 740 °C, and γ-Bi2O3 forms at about 740 °C. Quenching from higher temperatures results in the formation of δ-Bi2O3 from the Bi-rich intergranular liquid. The formation of barriers to electrical conduction at individual ZnO junctions was studied by use of microelectrodes. The barriers started to form while cooling between the temperatures of 1000 and 800 °C. Quenching from higher temperatures did not result in varistor behavior, but barriers to electrical conduction could be created in such specimens by post-sintering heat treatments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343783
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  • 6
    Electronic Resource
    Electronic Resource
    The effect of Bi2O3 content on the microstructure and electrical properties of ZnO varistor materials (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 4317-4324 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The microstructures of three ZnO varistor materials with different Bi2O3 contents have been evaluated by analytical electron microscopy in combination with x-ray diffractometry. The results have been correlated to microelectrode measurements, where breakdown voltages of individual ZnO junctions were measured, and also to current/voltage characteristics of bulk specimens. The volume fraction of the continuous intergranular network of Bi-rich phases, which lies along the triple junctions of the ZnO grains, increases with increasing Bi2O3 content, The conductivity of this network is strongly influenced by its internal microstructure. It was found that increased volume fractions of δ-Bi2O3 and less interpenetration between α-Bi2O and δ-Bi2O3 increases the conductivity of the network. Individual ZnO/ZnO grain boundaries exhibited breakdowns at 3.2 and 3.6 V, depending upon whether they contained segregated Bi atoms or thin Bi-rich amorphous films. The current/voltage characteristics of heterojunctions between ZnO and intergranular Bi2O3 were asymmetrical with respect to the polarity of the applied voltage. It was found that α-Bi2O3 and δ-Bi2O3 give rise to different breakdowns for electrons traveling from the Bi2O3 into an adjacent ZnO grain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343978
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  • 7
    Electronic Resource
    Electronic Resource
    Determination of the crystal symmetry of two Al–Fe–Si phases by convergent-beam electron diffraction (1987)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 20 (1987), S. 425-427 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The crystal symmetries of two precipitate phases, q1-AlFeSi (C-centred orthorhombic) and q2-AlFeSi (monoclinic), which were discovered in a dilute Al–Fe–Si alloy, have been determined with the use of convergent-beam electron diffraction (CBED). The space group of q1-AlFeSi is Cmmm and that of q2-AlFeSi is Pm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889887086369
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  • 8
    Electronic Resource
    Electronic Resource
    The formation of multipoles during high-temperature creep of austenitic stainless steels (1981)
    Springer
    Journal of materials science 16 (1981), S. 2860-2866 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract It is shown that multipole dislocation configurations can arise during power-law creep of certain austenitic stainless steels. These multipoles have been analysed in some detail for two particular steels (Alloy 800 and a modified AISI 316L) and it is suggested that they arise either during instantaneous loading or during the primary creep stage. Trace analysis has shown that the multipoles are confined to {1 1 1} planes during primary creep but are not necessarily confined to these planes during steady-state creep unless they are pinned by interstitials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00552971
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  • 9
    Electronic Resource
    Electronic Resource
    The microstructure of a ZnO varistor material (1985)
    Springer
    Journal of materials science 20 (1985), S. 4091-4098 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The microstructure of a ZnO varistor material has been investigated by a combination of X-ray diffractometry and analytical electron microscopy (SEM, TEM, STEM, EDX). The material was found to consist of: ZnO grains (doped with manganese, cobalt and nickel); smaller spinel grains which hinder the growth of ZnO grains during sintering; intergranular Bi-rich phases (namely α-Bi2O3, pyrochlore and an amorphous phase); and a small proportion of ZnO-ZnO interfaces which did not have any intergranular film but to which bismuth had segregated. The intergranular microstructure is largely a result of processes which occur during liquid phase sintering and subsequent cooling to room temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00552403
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  • 10
    Electronic Resource
    Electronic Resource
    Crystallization of the glassy phase in an Si3N4 material by post-sintering heat treatments (1987)
    Springer
    Journal of materials science 22 (1987), S. 4369-4376 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract It is shown that post-sintering heat treatments in air in the temperature range 1100 to 1400° C result in substantial crystallization of the glassy phase in an Si3N4 material which was produced by the nitridation pressureless sintering (NPS) method using Y2O3 and Al2O3 as sintering aids. X-ray diffraction combined with analytical electron microscopy showed that the secondary crystalline phases which form are strongly dependent upon time and temperature of heat treatment as well @S depth below the oxide scale. This effect is primarily due to the outward diffusion of cations (yttrium, aluminium and impurities) as well as the inward diffusion of oxygen. Small glassy pockets and thin amorphous intergranular films remain in the microstructure after heat treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01132031
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