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  • 1
    Electronic Resource
    Electronic Resource
    Electrical resistance changes of germanium during solidification under high pressure (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 5003-5005 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Changes in electrical resistance of germanium were investigated during melting and cooling under high pressure. It was found that the electrical resistances of the samples dropped abruptly at an early stage of the solidification above ∼4 GPa. This result shows a metallic liquid to metallic solid transition of germanium when cooling above ∼4 GPa as compared to a metallic liquid to nonmetallic solid transition at pressures below ∼4 GPa. The mechanism of the phase evolution in the solidification process of germanium at high pressures is briefly discussed. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.367308
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  • 2
    Electronic Resource
    Electronic Resource
    Nucleation of Al-Cu-Fe alloy in a drop tube (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 7559-7561 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The undercooling and nucleation of an Al65Cu20Fe15 alloy have been investigated with a 1.2-m-long drop tube. Melted droplets solidified either in vacuum or in helium. Various size samples in the forms of a globule, a fine fiber, and an irregular splat were collected at the bottom of the tube. X-ray phase identification results indicated that the CsCl-type cubic phase with a lattice parameter of 2.94 A(ring) and Al-Cu-Fe icosahedral quasicrystalline phase coexist in most specimens. However, the amount of each phase differs in various size samples due to the different cooling rates and undercoolings. It can be concluded that deep undercooling is beneficial to the formation of the Al-Cu-Fe icosahedral phase. In addition, in some rapidly solidified fine fibers (〈105 K/S), the Al-Cu-Fe ternary amorphous phase was also observed by high resolution transmission electron microscopy. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357989
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  • 3
    Electronic Resource
    Electronic Resource
    Nucleation of the Al4Mn alloy during containerless solidification in a drop tube (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 4334-4338 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The undercooling and nucleation of Al4Mn alloy have been investigated by containerless solidification in a 1.2 m long drop tube, where molten droplets of the alloy solidified in the vacuum. Droplets in various sizes were collected at the bottom of the tube. It is found by x-ray and electron diffractions that besides the orthorhombic Al6Mn and β-Mn phases, two approximants of the decagonal quasicrystal, one approximant of the icosahedral quasicrystal and decagonal domains can be observed in the as-solidified droplets. However, due to the different cooling rate or undercooling in the samples of different sizes, the phases mentioned above will appear in different amounts. The relationship between the phase composition and the sample size is discussed on the basis of the classical nucleation and growth theories. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359457
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  • 4
    Electronic Resource
    Electronic Resource
    Green emission from B2N2CO thin films doped with Tb (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 81 (2002), S. 34-36 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Visible light emission has been obtained at room temperature by photoluminescence (PL) and cathodoluminescence (CL) from Tb-doped B2N2CO thin films prepared by radio-frequency magnetron sputtering. The films were deposited by sputtering TbBn (n=4, 6, 12, 25, and 50) targets in an atmosphere of Ar and N2 gas mixture. The films are uniformly composed of very small particles with particle size of about 20–40 nm, which consist of turbostratic BN phase and amorphous phase. The characteristic PL peaks are observed in the spectral range from 300 to 800 nm, and correspond to the two groups of transitions of Tb3+ ions: 5D3→7FJ (J=6, 5, 3) and 5D4→7FJ (J=6, 5, 4, 3). The strongest PL peak at ∼547.2 nm is about four times greater than the other signals in the investigated range, indicating that the films have strong green light emission. CL intensity is very weakly dependent on the temperature. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1490143
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  • 5
    Electronic Resource
    Electronic Resource
    Microstructure of germanium quenched from the undercooled melt at high pressures (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 617-619 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The solidification behavior of germanium quenched from the melt at pressure of 2–7 GPa is presented. The solidification parameters of specimen were directly measured under high pressure. The microstructure of specimen was observed by electron microscopy. From the measured undercooling and average grain size, the interfacial free energy and activation energy of crystal growth under high pressures were estimated according to classical nucleation theory. Using high resolution transmission electron microscopy (HRTEM), crystals of sizes ranging from 5 to 100 nm surrounded by an amorphous matrix of germanium were found in those samples which quenched from deeply undercooled melt. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.115407
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  • 6
    Electronic Resource
    Electronic Resource
    Quenching with rapid decompression—a new method for rapid solidification (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 3811-3813 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report that a rapid drop of pressure applied to a melt whose crystallization point is a decreasing function of the pressure may, if the temperature, the initial pressure, and the final pressure are appropriately chosen, be equivalent to a rapid thermal quenching. In particular, it may lead to the formation of metastable crystalline or glassy phases bulk materials. The method might be useful to simulate adiabatic decompressions subsequent to shocks such as meteorite impacts. The relation between the undercooling rate (νc) obtained by rapid decompression and the rate of pressure release (νp) is given by νc=kνp, where k is the drop rate of the melting point with pressure. This method is evaluated for the Al–Ge system. The solidification products are either stable or metastable crystalline compounds, depending on the rate at which the pressure is released. Our experimental results indicate that quenching with rapid decompression is an effective method to generate high undercooling rates exceeding 105 Ks−1. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.120542
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  • 7
    Electronic Resource
    Electronic Resource
    Formation of the high temperature β phase in nanostructured Ni60Sb40 mixture under pressure (1997)
    Springer
    Journal of materials science 16 (1997), S. 4-7 
    Details
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/B:JMSL.0000044719.21657.70
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