Showing papers on "Texture (crystalline) published in 1982"
TL;DR: By extrapolating the Arrhenius plots for carbonization and experimental thermal progressive graphitization, it has been shown that carbonization can go to completion in nature (ΔH ≈ 65 kcal/mole), whereas progressive graphITization is thermodynamically improbable as discussed by the authors.
161 citations
TL;DR: In this article, the texture and growth patterns of sputtered MoS 2 films deposited onto substrates were identified from the textures and growth pattern of the surface microcrystallites, and the change in optical properties was explained.
133 citations
TL;DR: In this paper, a methodological study on the waterbinding properties of protein gels was made, where two tests were evaluated and only one of them, the "net test", was found useful for work on protein gel.
Abstract: A methodological study on the waterbinding properties of protein gels was made, where two tests were evaluated. Only one of them, the “net test,” was found useful for work on protein gels. The moisture loss of blood plasma gels was then studied as a function of heating temperature, heating time, pH, protein concentration, and sodium chloride concentration. It was finally demonstrated that a change in the gel structure may affect waterbinding and texture characteristics differently, and these properties should therefore be treated separately when evaluating protein gels. It was, e.g., shown that blood plasma gels became firmer with increasing heating temperature from 72 – 92°C, whereas the waterbinding properties became poorer at temperatures above 77°C and had an optimum at 75 – 77°C.
88 citations
TL;DR: In this paper, the effect of various grain structures, produced by thermomechanical treatments, on the monotonie tensile properties of the Al-Cu-Li-Mn-Cd alloy 2020 was investigated.
Abstract: The effect of various grain structures, produced by thermomechanical treatments, on the monotonie tensile properties of the Al-Cu-Li-Mn-Cd alloy 2020 was investigated. Materials having a completely or partially recrystallized structure exhibit elongations between 4 and 8 pct when aged to peak strength. For both cases the low ductility is associated with (a) planar deformation, (b) random texture, (c) the presence of large intermetallic compounds along the recrystallized grain boundaries, and (d) precipitate free zones. The first three enhance crack nucleation at high angle grain boundaries, and subsequent crack propagation occurs along the precipitate free zones. The completely unrecrystallized materials have elongations between 10 and 13 pct in both longitudinal and transverse directions. The high ductility is associated with a sharp texture and a transgranular fracture mode. The maximum ductility is obtained by reducing the unrecrystallized grain size. The results of this study suggest that improved properties of a 2020-type alloy may be obtained by lowering the Fe and Si contents to remove coarse constituent phases, eliminating Cd, and replacing Mn with Zr in order to obtain a highly textured, unrecrystallized structure.
78 citations
TL;DR: The theory of preferred orientation determined by Mossbauer spectroscopy using unpolarized dipole radiation in the case of axial hyperfine interaction was discussed in this paper. But the theory was not applied to the case where the reference axes were rotated.
Abstract: The authors discuss the theory of preferred orientation, determined by Mossbauer spectroscopy using unpolarised dipole radiation in the case of axial hyperfine interaction. A previous expansion of the texture function D( theta , phi ) in a series of spherical harmonics, involving five independent parameters, can be reduced by convenient rotation of the reference axes: in any case, there is an orthogonal set of 'principal axes' for which texture respects D2h symmetry. As a consequence, any texture can be described through three angular parameters and three numbers Nx, Ny, Nz representing 'populations' of spins parallel to the principal axes (Nx+Ny+Nz=1). In addition, they give general methods of obtaining texture-free spectra. Examples are given.
78 citations
TL;DR: In this paper, the pore texture of Raney-nickel was determined by impedance measurements carried out over a wide frequency range and the impedance obtained could be characterized by three resistances, R, Re and Rt and one capacitor C. R is the high frequency limit of the electrode impedance, and is equal to the electrolyte resistance between the reference capillary tip and the upper surface of catalyst layer.
75 citations
TL;DR: In this article, the electrical properties of oxidized polysilicon (polyoxide) were measured for samples of various thicknesses, grown from poly silicon which had been doped at temperatures of 900-1000°C, and oxidized in steam or dry oxygen at temperatures between 850-1050°C.
Abstract: The electrical properties of oxidized polysilicon (poly‐oxide) were measured for samples of various thicknesses, grown from polysilicon which had been doped at temperatures of 900–1000 °C, and oxidized in steam or dry oxygen at temperatures of 850–1050 °C. The electrical conduction can be explained in terms of Fowler‐Nordheim tunneling at sites of roughness of the polysilicon/poly‐oxide interface, and in terms of deep electron traps near that interface, in agreement with previously published results. We have found additional evidence for such electron traps. We find that higher doping and oxidation temperatures tend to yield oxides with higher breakdown fields, although there is considerable variation among different sets of samples. We observe no significant differences in the polysilicon/poly‐oxide interface texture by cross‐sectional transmission electron microscopy. However, we find a strong correlation between the applied field necessary for a significant leakage current through the poly‐oxide and th...
65 citations
TL;DR: In this article, the inclination angle αc of columnar grains and the degree P of orientation of texture were investigated for iron films prepared at various substrate temperatures, and the dependence of αc and P on substrate temperature was explained by the Ts dependence of the adatom mobility.
53 citations
TL;DR: In this article, the possibility of converting a gel into glass by sintering depends on a competition between the phenomena which lead to densification and those which promote crystallization, and it is shown that in the case of gels, a heterogeneous nucleation mechanism is active which explains the variations of behaviour observed for gels prepared by different techniques.
Abstract: The possibility of converting a gel into glass by sintering depends on a competition between the phenomena which lead to densification and those which promote crystallization. Sintering kinetics are presented for a close-pore texture and an open-pore texture and the influence of various parameters is discussed. The devitrification versus compaction problem is studied using TTT diagrams. It is shown that in the case of gels, a heterogeneous nucleation mechanism is active which explanins the variations of behaviour observed for gels prepared by different techniques.
53 citations
TL;DR: In this paper, it was shown that increasing amounts of silicon progressively reduce the oxidation rate within the range [Si ] = 0 − 1 w o and a variety of physical techniques have been used to examine oxidized specimens in pursuit of the origins of this beneficial influence.
51 citations
TL;DR: In this article, an analysis of interfacial texture created during the wet oxidation of polycrystalline silicon (polysilicon) over the temperature range 950°-1100°C was made, and the effect of this texture on oxide breakdown was discussed.
Abstract: An analysis has been made of interfacial texture created during the wet oxidation of polycrystalline silicon (polysilicon) over the temperature range 950°–1100°C, and the effect of this texture on oxide breakdown. Four types of interfacial textural features are described: interface roughness due to initial polysilicon surface texture, "bumps" caused by anomalous polysilicon nucleation at local sites of contamination, "protuberances" that occur during oxidation, and inclusions of unoxidized silicon within the oxide. Models for the generation of the last two defects are presented, and the role of interfacial texture in dielectric breakdown is discussed.
Journal Article•
TL;DR: In this paper, the effect of the thermomechanical coupling on the homeotropic texture of a compensated cholesteric was investigated, and the coefficient for the deformation was estimated.
Abstract: The effect of the thermomechanical coupling on the homeotropic texture of a compensated cholesteric in investigated. The thermomechanical coupling coefficient is estimated for the deformation.
TL;DR: In this article, it is shown that the doubling of one of the perovskite cell axes appears at random in the a, b or c directions within the same crystal.
TL;DR: In this paper, the authors used high sputtering gas pressures to promote the growth of possible metastable phases and to allow preferred orientation effects to be present in the films, and showed a predominant (110) texture, for oxygen levels in the SmCo5 films of greater than about 6 at.
Abstract: Ferromagnetic films of the Sm–Co and Sm–Fe systems have been synthesized by sputtering onto substrates at temperatures above 600 °C so that the deposit is directly crystallized upon deposition. For the directly synthesized phases, high sputtering gas pressures were used so that the sputtered atoms transferred excess momentum to the sputtering gas atoms before arriving at the substrate. The object has been to promote the growth of possible metastable phases and to allow preferred orientation effects to be present in the films. Directly synthesized SmCo5 films grown by this method, showed a predominant (110) texture, for oxygen levels in the films of greater than about 6 at. %. As the oxygen incorporation level in the SmCo5 films was reduced to 1.4 at. % oxygen, only a (200) texture was observed. In Sm–Fe films with 6.5 at. % oxygen, a new metastable phase forms at the 1–5 composition. This oxygen stabilized metastable phase is not present in Sm–Fe films made with lower amounts of oxygen incorporation.
TL;DR: In this paper, the effect of texture on the acoustoelastic response in polycrystalline bodies was examined and the second and third-order elastic constants of the polycrystal were derived from the elastic properties of the constituent crystals, and the crystalline orientation relative to the body's symmetry axis.
Abstract: Acoustoelasticity is an ultrasonic technique which has been used for the determination of active and residual stresses in common structural materials. This paper examines the effect of texture on the acoustoelastic response in polycrystalline bodies. In particular materials which are transversely isotropic aggregates of cubic crystals are studied. The second- and third-order elastic constants of the polycrystal are derived from the elastic properties of the constituent crystals, and the crystalline orientation relative to the body's symmetry axis. The acoustoelastic relations between velocity and deformation are then presented for the aggregate. Finally, evaluation of the acoustoelastic response for several ideal textures using data for aluminum single crystals shows that the response is highly dependent on the texture.
TL;DR: In this article, the authors investigated the effect of crystallographic texture, heat treatment, and microstructure on crack propagation in Zircaloy at 300 °C in four Pa flowing iodine environment.
Abstract: An investigation of stress corrosion crack propagation in Zircaloy is performed at 300 °C in four Pa flowing iodine environment. By varying the orientation of fracture mechanics specimens, the effect of crystallographic texture, heat treatment, and microstructure onK
ISCC is studied. Texture is found to have a strong effect on bothK
ISCC and the fracture path. As the resolved fraction of basal poles parallel to the direction of crack opening decreases,K
ISCC in stress-relieved material increases from 4 MPa√m atf = 0.70 to 17 MPa√m atf = 0.19. The same trend is observed in recrystallized material. However, theK
ISCC values are somewhat greater. Transgranular cleavage is the preferred mode of crack propagation. Several ductile modes of separation complement the cleavage process. At high crack velocity, tearing between facets is promoted. At lowK, nearK
ISCC, very little tearing is observed and cleavage zones larger than the grain size are common. Fluting is preferred in the low regime. In recrystallized material a transition to completely intergranular failure is observed nearK
ISCC.
TL;DR: In this article, the optical absorption edge spectra, the bonded H content and H evolution measurements have been carried out on B-doped a-Si:H as functions of the dopant gas ratio of B2H6/SiH4.
Abstract: The optical absorption edge spectra, the bonded H content and H evolution measurements have been carried out on B-doped a-Si:H as functions of the dopant gas ratio of B2H6/SiH4. The number of H atoms bonded to Si network decreases as the doping ratio increases, while non-bonded H's are involved only in the heavily B-doped specimen. It has been demonstrated that the film texture changes drastically in a high doping region, resulting in anomalous change in the optical absorption spectra over a whole photon-energy range.
TL;DR: In this paper, the authors showed that ultramicrotomed sections of porous anodic films develop a textured appearance upon exposure to the electron beam, which has not been related unambiguously to specific regions of the film observed previously in the plan views of the respective ion beam thinned films.
TL;DR: In this paper, it was shown that ninhydrin, a reagent capable of irreversibly binding with free amino groups, significantly inhibited texture formation, while the soluble fraction of acylated proteins demonstrated increased electrophoretic mobility as a result of the loss of the cationic amino groups.
Abstract: Data were gathered to further support the hypothesis that formation of texture, measured in terms of shear values and sensory responses, during the thermal extrusion of soy protein involves protein-protein interactions based on NH 2 groups. It was shown that ninhydrin, a reagent capable of irreversibly binding with free amino groups, significantly inhibited texture formation. When texturization was studied as a function of pH adjustment (~4–10), maximum Warner-Bratzler shear values and sensory response were found to occur close to pH 8, where amino groups are unprotonated and more reactive. At the extremes of the pH range extrudates lost structural integrity, were more soluble, and an examination of their microstructure showed that the interconnected longitudinal vacuoles separated by thick cell walls normally seen were replaced by a denser globoid system. Soy protein isolate was acylated using either acetic or succinic anhydride. Both treatments resulted in a significant decrease in extrudate texture but increases in extrudate solubility; the latter finding tends to discount the importance of solubility in texture formation. Scanning electron microscopy revealed that the acylated extrudates exhibited less cellularity and were denser than the control materials. The soluble fraction of acylated proteins demonstrated increased electrophoretic mobility as a result of the loss of the cationic amino groups.
TL;DR: In this article, thin liquid crystal films in the range from 0.4 to 10 μm were thermally evaporated on solid surfaces and maintained on obliquely evaporated SiO surfaces that induce homeotropic, homogeneous, or tilted alignment.
Abstract: Thin liquid crystal films in the range from 0.4 to 10 μm were thermally evaporated on solid surfaces. Semistable films were maintained on obliquely evaporated SiO surfaces that induce homeotropic, homogeneous, or tilted alignment. Realignment which violates the boundary conditions was observed in the smectic phase of thin films. The nematic phase of homogeneously aligned films has a peculiar two‐domain texture indicative of a spontaneous twist due to conflicting and degenerate boundary conditions.
TL;DR: In this paper, structural differences between the wheel (chill) and upper sides of the melt-spun ribbons were investigated by optical and scanning electron microscopy and X-ray diffraction methods (texture and size-strain analyses).
Abstract: Hypo- and hyper-eutectic AlSi alloys were rapidly quenched from the melt using the melt-spinning technique with two spinning velocities. Structural differences between the wheel (chill) and upper sides of the melt-spun ribbons were investigated by optical and scanning electron microscopy and X-ray diffraction methods (texture- and size-strain analyses). The Al-rich phase of the hypo-eutectic alloys was textured. The textures observed from both sides of the ribbons were different; in neither case was it of fibre type. For the larger spinning velocity applied, the structural imperfection of the wheel side was larger than that of the upper side for both the Al-rich and the Si-rich phases.
TL;DR: In this paper, a tensile strain aligns the spins parallel to the ribbon length, thus demonstrating a positive magnetostriction, and the observed spin texture depends upon the width of the ribbons and varies from the centre to the edges.
Journal Article•
TL;DR: In this article, structural differences between the wheel (chill) and upper sides of the melt-spun ribbons were investigated by optical and scanning electron microscopy and X-ray diffraction methods (texture and size-strain analyses).
Abstract: Hypo- and hyper-eutectic AlSi alloys were rapidly quenched from the melt using the melt-spinning technique with two spinning velocities. Structural differences between the wheel (chill) and upper sides of the melt-spun ribbons were investigated by optical and scanning electron microscopy and X-ray diffraction methods (texture- and size-strain analyses). The AI-rich phase of the hypo-eutectic alloys was textured. The textures observed from both sides of the ribbons were different; in neither case was it of fibre type. For the larger spinning velocity applied, the structural imperfection of the wheel side was larger than that of the upper side for both the AI-rich and the Si-rich phases.
01 Jan 1982
TL;DR: In this article, the concept of hydrogen shuttling is introduced to explain the successful use of pitch additives in coal blends, which is a major part of the optical texture of metallurgical cokes.
Abstract: Metallurgical coke has an optical texture or microstructure composed of anisotropic carbon in the form of mosaics and flow-type anisotropy as well as isotropic carbon or inerts. The anisotropic carbon is formed via the intermediates of nematic liquid crystals and mesophase. The physical and chemical properties of the coal ultimately control the fluidity of the carbonization system and this, in turn, is important in controlling the size and shape of resultant anisotropy in the coke. Each component of the optical texture makes a contribution to coke performance. The interlocked, randomly orientated units of the mosaics, 1 to 10 ..mu..m diameter, are more resistant to crack propagation and fracture than is the isotropic carbon or the flow-type anisotropic carbon (length > 10 ..mu..m). Anisotropic carbon is more resistant to gasification than is isotropic carbon and this factor is relevant in discussion of solution-loss in the blast furnace. The mosaic units of anisotropic carbon, on gasification, do not develop the fissures which ooccur in the flow-type anisotropy and hence coke strength can be maintained relatively. The mosaics, which constitute a major part of the optical texture of metallurgical cokes, are more resistant to attack by alkali than the flow-type anisotropy. The isotropicmore » carbon is probably more resistant. Co-carbonizations are described which produce cokes with these suitable optical textures. The concepts of hydrogen shuttling is introduced to explain the successful use of pitch additives in coal blends.« less
TL;DR: Ion beam sputtering was used to deposit thin films of PbS for use as solar selective absorbers as mentioned in this paper, which showed that ion-beam-deposited films were harder than thermally produced films, had a smaller mean crystallite size of about 500 A and had a surface relatively free of any texture.
TL;DR: In this paper, a test matrix was devised to separate the effects of crystallographic texture, heat treatment, residual stress, and surface finish on SCC susceptibility in Zircaloy-2 cladding to compare iodine stress corrosion cracking susceptibilities at ~593°K and an iodine concentration of 10−4 g/cm2.
TL;DR: In this article, the changes in texture and substructure induced in commercial purity aluminum by conventional (cross-rolling) and shock wave deformation (peak pressure, 5.8 GPa; pulse duration, 2.8 μs) were studied by X-ray diffraction and transmission electron microscopy.
TL;DR: In this article, the evolution of texture as determined by a puncture test and of the intensity of fungal rot in mangoes was considered, where the fruits were placed at room temperatures after 3 wk storage at 4° or 12°C under various humidity conditions.
Abstract: In this study we have considered the evolution of texture as determined by a puncture test and of the intensity of fungal rot in mangoes. Fruits were placed at room temperatures after 3 wk storage at 4° or 12°C under various humidity conditions. Observed differences in hardness (INSTRON) of the skin and the flesh appeared related to fruit ripening. Inducing chilling-injury on fruits initially stored at 4°C accelerated softening after fruits were transferred at 20°C. Gradual humidification of ambient atmosphere reduced this phenomenon, especially by limiting water losses, thus maintaining cell turgescence. Susceptibility to fungal rotting increased with fruit softening. Fungi proliferation seemed more rapid on chilling-injured batches. A clear relationship was evidenced between water losses and fungal development.