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  • 1
    Electronic Resource
    Electronic Resource
    Fabrication of Porous Aluminium and Copper Media by Using Monotectic Solidification under a Magnetic Field (2006)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 512 (Apr. 2006), p. 289-294 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Unidirectional solidification of Al-In, Cu-Pb and Cu-Pb-Al monotectic alloys wasperformed under static magnetic fields up to 10T for formation of the regularly aligned-rod structure. mThe imposition of static magnetic fields exceeding 4T suppressed movement of the In liquid droplets at the Al solidifying front and enhanced the engulfment of the In droplets into the front. As a result,the eutectic-like structure was obtained in the Al-10 and 15at%In hypermonotectic alloys. The micro X-ray tomography indicated that the continuous In rods with diameters of 10-20 µm were aligned parallel to each other. In the case of the Cu-Pb and the Cu-Pb-Al alloys, the imposition of static magnetic fields also enhanced the formation of the aligned Pb rods. The electrochemical etching by using a 10% HNO3 solution successfully removed the minor phase, and the porous aluminum andcopper with deep pores were fabricated
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/12/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.512.289.pdf
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  • 2
    Electronic Resource
    Electronic Resource
    Magnesium isotopic fractionation of silicates produced in condensation experiments
    Amsterdam : Elsevier
    Earth and Planetary Science Letters 107 (1991), S. 138-147 
    Details
    ISSN: 0012-821X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0012-821X(91)90050-R
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  • 3
    Electronic Resource
    Electronic Resource
    An experimental study of enstatite formation reaction between forsterite and Si-rich gas
    Amsterdam : Elsevier
    Earth and Planetary Science Letters 118 (1993), S. 21-30 
    Details
    ISSN: 0012-821X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0012-821X(93)90156-4
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  • 4
    Electronic Resource
    Electronic Resource
    Experimental reproduction of textures of chondrules
    Amsterdam : Elsevier
    Earth and Planetary Science Letters 48 (1980), S. 155-165 
    Details
    ISSN: 0012-821X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0012-821X(80)90178-8
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  • 5
    Electronic Resource
    Electronic Resource
    Distribution of elements in growth of (Ba,Pb)(NO"3)"2 crystals from the aqueous solution
    Amsterdam : Elsevier
    Journal of Crystal Growth 55 (1981), S. 510-516 
    Details
    ISSN: 0022-0248
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0022-0248(81)90108-1
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  • 6
    Electronic Resource
    Electronic Resource
    Diamagnetic anisotropy of sheetsilicates (1993)
    Springer
    Physics and chemistry of minerals 20 (1993), S. 369-374 
    Details
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract The diamagnetic properties of sheetsilicates are studied by measuring the magnetic orientation of micron-sized crystals. In the case of synthetic phlogopite with the average diameter of 0.65 μm and the thickness of 0.2 μm, the alignment of the grains is achieved in the magnetic field below 35 kOe. The planes of the platy single-crystal grains were alignned parallel to the field when the alignment was achieved. The alignment of the grains is realized because the field-induced anisotropic energy, caused by the diamagnetic anisotropy in the mineral's crystal structure, exceeds thermal agitation energy in the applied field. By analyzing the field dependence of grain alignment, the diamagnetic anisotropy per formula unit, Δχ, of sheetsilicate mineral is estimated even if a large single crystal is not provided. The field-induced anisotropic energy is proportional to NΔχ where N is the number of molecules in the grain. A linear correlation has been found between the Δχ value and the F/OH mole ratio among the measured sheetsilicates. This correlation supports the assumption that the hexagonally packed oxygen-layer in the crystal lattice induces the anisotropies of the sheetsilicates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00203105
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  • 7
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    Magnetite plaquettes are naturally asymmetric materials in meteorites (2016)
    Mineralogical Society of America
    Details
    Publication Date: 2016-09-02
    Description: Life on Earth shows preference toward the set of organics with particular spatial configurations. Enantiomeric excesses have been observed for α-methyl amino acids in meteorites, which suggests that chiral asymmetry might have an abiotic origin. A possible abiotic mechanism that could produce chiral asymmetry in meteoritic amino acids is their formation under the influence of asymmetric catalysts, as mineral crystallization can produce spatially asymmetric structures. Although magnetite plaquettes have been proposed to be a possible candidate for an asymmetric catalyst, based on the suggestion that they have a spiral structure, a comprehensive description of their morphology and interpretation of the mechanism associated with symmetry-breaking in biomolecules remain elusive. Here we report observations of magnetite plaquettes in carbonaceous chondrites (CC) that were made with scanning electron microscopy and synchrotron X-ray computed microtomography (SXRCT). We obtained the crystal orientation of the plaquettes using electron backscatter diffraction (EBSD) analysis. SXRCT permits visualization of the internal features of the plaquettes. It provides an unambiguous conclusion that the plaquettes are devoid of a spiral feature and, rather that they are stacks of individual magnetite disks that do not join to form a continuous spiral. Despite the lack of spiral features, our EBSD data show significant changes in crystal orientation between adjacent magnetite disks. The magnetite disks are displaced in a consistent relative direction that lead to an overall crystallographic rotational mechanism. This work offers an explicit understanding of the structures of magnetite plaquettes in CC, which provides a fundamental basis for future interpretation of the proposed symmetry-breaking mechanism.
    Print ISSN: 0003-004X
    Electronic ISSN: 1945-3027
    Topics: Geosciences
    Published by Mineralogical Society of America
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  • 8
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    Combined FIB microsampling and X-ray microtomography: a powerful tool for the study of tiny fluid inclusions (2016)
    Schweizerbart
    Details
    Publication Date: 2016-05-17
    Description: Detailed morphological studies including phase-volume estimation were performed on a natural fluid inclusion in an eclogite-facies rock collected from the Sanbagawa metamorphic belt in Japan. The studied fluid inclusion, which is composed of H 2 O–NaCl liquid and a CH 4 bubble, was picked up by using a focused ion beam (FIB) system and investigated by synchrotron-radiation-based X-ray microtomography (XCT), which provides a submicrometer spatial resolution. By using the FIB-XCT technique, we can perform detailed three-dimensional morphological studies on tiny objects (〈10 μm) in combination with several other analytical techniques, such as Raman spectroscopy. The XCT image of the fluid inclusion (~7 μm in size) clearly shows a faceted shape, which corresponds fairly well to the interfacial relationship of α-quartz. This euhedral morphology also satisfies the crystal orientation of the host quartz, and hence is considered a negative crystal. The XCT determination of liquid and vapor-phase volumes in the fluid inclusion is in excellent accordance with the value estimated by the combination of microthermometry and the equation of state of the H 2 O–NaCl–CH 4 system. Furthermore, this agreement indicates that XCT observation is applicable for volumetric analysis of more complex multi-phase systems, regardless of their compositions and phase numbers. Combining the volume fraction of the fluids with the characterization and densimetry of each liquid/gas phase, we can accurately estimate the bulk composition and molar volume of the fluid inclusion. The isochore calculation of the estimated bulk properties shows lower- P conditions than the peak P-T conditions of the rock, although the inclusion was trapped during the pressure-increasing stage. This is possibly caused by density re-equilibration during decompression and cooling of the host metamorphic rock. The estimated isochore and the decompression P-T path from literature intersect at 0.2–0.3 GPa and 300°C, which is consistent with the fluid density closure temperature proposed in the literature for quartz-hosted fluid inclusions. The present study demonstrates powerful potential of the FIB-XCT technique for performing morphological observations on tiny fluid inclusions a few micrometers across. With increasing availability of high-resolution XCT systems, the FIB-XCT technique combined with existing fundamental methods provides a new investigative tool for fluid inclusion studies, and may be especially valuable for complex inclusions that are difficult to analyze by other methods.
    Print ISSN: 0935-1221
    Electronic ISSN: 1617-4011
    Topics: Geosciences
    Published by Schweizerbart
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  • 9
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    Three-dimensional study by synchrotron radiation computed tomography of melt distribution in samples doped to enhance contrast (2017)
    Mineralogical Society of Great Britain and Ireland
    Details
    Publication Date: 2017-10-11
    Description: The three-dimensional distribution of melt in partially molten synthetic samples compositionally corresponding to diopside (90 wt.%)–anorthite (10 wt.%) and doped with PbO, WO 3 , MoO 3 , or Cs 2 O to enhance contrast was studied by X-ray computed tomography (CT) with synchrotron radiation. The heavy elements were strongly concentrated in the melt and contributed to an increase of the X-ray linear attenuation coefficient (LAC) of it. PbO was found to be compatible with silicate melt (〉20 wt.% in solution) and incompatible with diopside crystals. Other oxides WO 3 (~10 wt.%), MoO 3 (~5 wt.%) and Cs 2 O (〈 5 wt.%) are also soluble only in the melt. Such doping is useful not only for LAC control in X-ray CT measurements, but also for systematic control of the structure (wetting properties, distribution and connectivity) of partial melt. This technique gives basic information for discussion of the 3D distribution of partial melt having different wetting properties. As PbO was most effective in visualization of the diopside–anorthite partially molten system, CT images of the PbO-bearing sample were used for further 3D investigation of distribution. A distribution of dihedral angles at solid-melt-solid triple junctions ranging from 22 to 55° was observed with the 3D data. This range in angle distribution was probably caused by anisotropy of crystals and the result supports the argument that there is some limitation in a theoretical framework of stereology which estimates the 3D structure based on 2D observations. Investigators have begun to apply X-ray CT to the study of the 3D distribution of partial melts in rocks using synchrotron radiation. Our study on the effect of doping is one approach for developing a technique to investigate 3D melt distribution.
    Print ISSN: 0026-461X
    Electronic ISSN: 1471-8022
    Topics: Geosciences
    Published by Mineralogical Society of Great Britain and Ireland
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  • 10
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    Asteroid Itokawa A Source of Ordinary Chondrites and A Laboratory for Surface Processes (2014)
    Mineralogical Society of America
    In: Elements
    Details
    Publication Date: 2014-02-18
    Description: The Japanese spacecraft Hayabusa returned samples from the surface of an asteroid (near-Earth S-type asteroid 25143 Itokawa) for the first time in human history. This article describes the results of the initial analysis of the mineralogy, micropetrology, and elemental and isotopic compositions of regolith particles from Itokawa measuring 30–180 μm in diameter. The results show a direct link between ordinary chondrites and S-type asteroids. The regolith particles provide evidence of space-weathering rims and grain abrasion, and the information obtained has elucidated various processes on the airless surface of Itokawa, such as the impact of small objects, grain motion, and irradiation by solar wind.
    Print ISSN: 1811-5209
    Electronic ISSN: 1811-5217
    Topics: Geosciences
    Published by Mineralogical Society of America
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