Melting of the light actinides

Lawson, A. C.; Artinez, B. M.; Roberts, J. A.; Bennett, B. I.; Richardson, J. W.

doi:10.1080/13642810008218339

Cited by 69 publications

(35 citation statements)

References 8 publications

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“…Then Eq. 5 has the melting point on both sides, but can nevertheless be solved explicitly, as shown by Lawson et al (2000aLawson et al ( , 2000c. The large (negative) value of c shown in Fig 14 gives a calculated value of the melting point that is in good agreement with the observed low melting point.…”

Section: Pu Meltingmentioning

confidence: 99%

“…% Ga (Lawson et al, 2000) 10 100 1000 Pu-2 at. % Ga (Lawson et al, 2000a) Pb (Lisher, 1976) The difference between anharmonic and harmonic softening is illustrated in Fig. 15, which shows plots of normalized Debye temperature, Θ/Θ 0 , versus the normalized lattice constant, a/a 295K for Pb and for Pu-2 at.…”

Section: Pu Meltingmentioning

confidence: 99%

“…% Ga, the thermal expansion is very small, and the Grüneisen effect cannot be important here. Instead, it has been suggested that these materials undergo "harmonic softening" as the temperature increases, and this is assumed to be a purely electronic effect (Lawson et al, 2000a, Manley et al, 2001). According to this suggestion, the large values of -c for the light actinides arise -at least in part -from harmonic softening.…”

Section: Pu Meltingmentioning

confidence: 99%

“…11 together with a plot of Θ DW for Pu-2 at. % Ga from Lawson et al (2000a) for comparison. The Θ DW s decrease with increasing temperature: such a trend is required for phase stability and is very similar to that in the alloy, except that there is a big jump between the Θ DW s of α-and β-Pu.…”

Section: Electron Correlation and Plutonium Phase Diagramsmentioning

confidence: 99%

“…This is a good model for the behavior of the Bragg intensities, and it is used routinely for the fitting of experimental diffraction data. The determination of <u 2 > vs. temperature data can be used to determine the Debye-Waller temperature, Θ DW , as a function of temperature (Lawson et al, 2000a). Θ DW is expected to be much more independent of temperature than is the heat capacity Debye temperature, Θ D , because its moment of the phonon spectrum shifts between -1 and -2 between low and high temperatures, while that of Θ D shifts between -3 and +2 (Grimvall, 1999), and the second moment has hardly any temperature dependence at all at high temperatures (Lovesey, 1984).…”

Section: Vibrational Correlationsmentioning

confidence: 99%

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Electron Correlation and Plutonium Phase Diagrams

Lawson

Roberts

Martinez

et al. 2002

Electron Correlations and Materials Properties 2

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Section: Pu Meltingmentioning

confidence: 99%

Section: Pu Meltingmentioning

confidence: 99%

Section: Pu Meltingmentioning

confidence: 99%

Section: Electron Correlation and Plutonium Phase Diagramsmentioning

confidence: 99%

Section: Vibrational Correlationsmentioning

confidence: 99%

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Electron Correlation and Plutonium Phase Diagrams

Lawson

Roberts

Martinez

et al. 2002

Electron Correlations and Materials Properties 2

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Anisotropy of thermal vibrations and polymorphic transformations in lanthanum and uranium

Blanter¹,

Глазков²,

Соменков³

2009

Physica Status Solidi (b)

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Average thermal atomic displacements along different crystallographic axes were measured for polycrystalline samples employing the method of neutron diffraction and defining the anisotropic Debye–Waller factor, obtained by processing the corresponding reflections. In the double hexagonal close‐packed lanthanum modification, the anisotropy of vibrations is insignificant at room temperature, yet it increases markedly with increasing temperature; also, the relative displacement (in relation to the corresponding lattice parameters) in the basal plane considerably exceeds that along the hexagonal axis. In orthorhombic α‐uranium, large anisotropy is observed even at room temperature, which increases with increasing temperature. It is clearly proved that in lanthanum and uranium the polymorphic transition of low‐temperature anisotropic phases into high‐temperature cubic modifications with isotropic thermal vibrations reduces the maximum relative quantity of thermal displacements at the expense of more homogeneous distribution of vibrations along the lattice axes, and thus probably ‘prevents’ the melting of low‐temperature modifications at a lower temperature due to the critical value of these displacements being reached. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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