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  • 11
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 5693-5695 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Neutron diffraction has been used to refine the crystallographic and magnetic structure of Nd5Fe17. The results of Rietveld refinement yield improved precision for the Fe coordinates relative to the x-ray study. The magnetic moments are refined by assuming that all Fe atoms in comparable environments have the same moment or by grouping sites by average Fe–Fe bond length. Each model leads to five distinct moments, in which the magnitude of the moment is correlated with both the average Fe–Fe bond lengths and the near-neighbor distribution. The results of the refinement are in reasonable agreement with the analysis of the Mössbauer spectra. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 38 (1997), S. 5153-5166 
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: In this paper we consider dissipative fluxes as well as the conserved variables as a set of independent variables characterizing the thermodynamic state of a nonequilibrium system. We then generalize the traditional internal energy balance equation so that contributions due to the dissipative fluxes are taken into consideration. On the other hand, the second law is formulated in terms of Caratheodory's inaccessibility condition in conjunction with the assumption that dissipative energy associated with internal work arising from irreversible processes be semipositive definite. We show that the second law formulated in this manner is equivalent to Kelvin's principle and Clausius's principle, as well as Clausius's inequality. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 40 (1999), S. 830-837 
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: In this paper we consider symmetry transformations of the generalized entropy function that preserve the Gibbs one-form (Gibbs relation). We show that this symmetry consideration naturally leads to the geometric structure of thermodynamics in terms of contact geometry. We also construct an example based on the van der Waals' fluid to illustrate the method discussed in the paper. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 38 (1997), S. 3589-3602 
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: In this paper we investigate the kinetic foundation of irreversible thermodynamics by means of the moment methods proposed by Grad and by Eu, respectively. First we show that the moment methods yield a weak solution of the Boltzmann equation. On the other hand, the entropy balance equation can be satisfied only by the strong solution of the Boltzmann equation. Second, we reformulate the energy balance equation in an alternative form where dissipative energy as well as a generalized work 1-form are included in this new equation. Assume that the dissipative energy is semi-positive definite. The local form of the second law of thermodynamics is then formulated in terms of the inaccessibility condition of Caratheodory. We then show that our new formulation of the second law is equivalent to Kelvin's principle and Clausius' principle. Finally we obtain a calotropy balance equation where the calotropy density function is a state function in the thermodynamic space. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 42 (2001), S. 2531-2539 
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: In this paper we consider symmetry transformations that preserve the first law and the second law of thermodynamics, as well as the pseudo-Riemannian structure of the Legendre manifold defined in terms of the second derivative matrix of the entropy function in extended irreversible thermodynamics. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 41 (2000), S. 7445-7457 
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: In this paper we investigate the kinetic foundation of extended irreversible thermodynamics via the moment method. First we consider the construct of the 1-particle distribution function f in terms of its moments by maximizing the entropy density function. We then project f from its L2 space onto the local thermodynamic variables z=(z1,...,zN) in the thermodynamic base space B(circumflex)N. Thus instead of the Boltzmann equation we consider a set of evolution equations of z in B(circumflex)N. Second, we formulate the laws of thermodynamics governing the variable z in B(circumflex)N. These laws exhibit an intrinsic geometric structure of thermodynamics in the setting of contact geometry. Finally, as an illustration, we discuss the evolution equations for the bulk pressure Pb, heat flux Q, and the symmetric traceless tensor π(two down arrows) corresponding to the viscous and heat conduction irreversible processes. These equations can be formulated as an abstract inhomogeneous hyperbolic evolution equation. By employing the C0 semigroup technique, we discuss the solution of the evolution equation and its asymptotic behavior. We show that thermodynamic stability condition of the system implies asymptotic dynamical stability of the solution and vice versa. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 39 (1998), S. 329-344 
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: In this paper we consider the second law of thermodynamics for a dissipative system and its symmetry property in terms of contact geometry. We first show that the inaccessibility condition of Caratheodory and the assumption of semipositive definite property of the dissipative energy are equivalent to Clausius' inequality. The inaccessibility condition then gives rise to a generalized Gibbs relation (GGR). By means of the GGR a 1-form ω can be defined such that the zero of ω reproduces the GGR. Such 1-form ω has the property ω∧(dω)n≠0 and ω∧(dω)n+1=0. The integral surface of the GGR is an n-dimensional 1-graph space G (Legendre submanifold) of a 1-jet space J1(En,R), where En is the base space of J1(En,R) with thermodynamic variables as its coordinates. The (2n+1)-dimensional J1(En,R) equipped with the 1-form ω is also called a contact bundle K, where the intensive thermodynamic variables are considered as the contact elements to K at every x. Next we construct an isovector field Xf such that the inaccessibility condition is invariant under the contact transformations generated by Xf. Finally, suppose under some specific assumptions the dynamical equations of the thermodynamic variables x can be approximated by the flow equations of a vector field XG on G. We can lift XG to Xf such that the 1-graph space G as well as the inaccessibility condition are preserved under the contact transformations generated by Xf. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 3450-3452 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An arsenic source, tris-dimethylaminoarsine (TDMAAs), was used as a p-type dopant for Hg1−xCdxTe prepared by metalorganic chemical vapor deposition (MOCVD). The Hg1−xCdxTe layers were grown using the interdiffused multilayer process (IMP) at 360 °C with dimethylcadmium, di-isopropyltelluride and elemental mercury. Hole concentrations at 77 K in the range of 2×10+16–7×10+17 cm−3 were obtained in Hg1−xCdxTe with x=0.2–0.35, and ∼30%–50% of the arsenic was electrically active based on the data from secondary ion mass spectrometry (SIMS) measurements. These MOCVD Hg1−xCdxTe layers show minority carrier lifetimes at 77 K in the range of 3 ns–4 μs, which compare favorably with those from the best arsenic-doped Hg1−xCdxTe films prepared by liquid phase epitaxy. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 2131-2133 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Fracture surfaces of a nanocrystallized Zr65Cu15Al10Pd10 metallic glass were observed on an atomic scale with field ion microscopy. Based on geometrical and phase characteristics of the fracture morphologies, it can be determined that a crack propagates along the interfaces between nanocrystals and the amorphous matrix in the alloy with optimized microstructures. Combining with macromechanical properties, it is proposed that the strengthening effect of nanocrystals in the Zr-based metallic glass arises from a strong interaction between nanocrystals and local shear bands during deformation processes of the glassy matrix. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 20
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 812-814 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report atom probe results on impurity oxygen dissolution in a Zr65Cu15Al10Pd10 metallic glass and its redistribution during nanocrystallization. Approximately 0.1 at. % impurity oxygen is detected from the as-melt-spun Zr65Cu15Al10Pd10 metallic glass. Oxygen redistribution occurs during annealing. In some crystallites, oxygen up to 4 at. % is detected, and virtually no oxygen is dissolved in the remaining amorphous phase. This result directly demonstrates that impurity oxygen promotes the crystallization by forming metastable phases containing high content oxygen and thereby influences the kinetics of crystallization. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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