Cerium isomorphism and the δ–α transformation in plutonium

Lawson, A. C.; Lashley, J. C.; Riseborough, Peter S.

doi:10.1016/j.jallcom.2006.09.082

Cited by 7 publications

(9 citation statements)

References 13 publications

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“…There is a critical point at T K = 550 K and p K = 18.8 kbar. The phase diagram is shown in figure 1, which closely resembles the phase diagram of the critical region of a fluid [1][2][3][4][5].…”

Section: Introductionmentioning

confidence: 76%

“…Similarly, again starting from 5 kbar, 400 K and gradually decreasing the temperature, one will encounter a volume discontinuity (contraction) at about 200 K. If, in different experiments, the equilibrium line is crossed at locations approaching the critical point (b), the size of the volume discontinuity will decrease and reach zero at the critical point. Johansson [2] and Eliashberg and Capellmann [4] suggested that the equilibrium line a-b be extended to (c) at the melting curve, and that The figure is redrawn from [5]. Descriptive formulas are from the Aptekar-Ponyatovsky (AP) theory [7] to be introduced later.…”

Section: Introductionmentioning

confidence: 99%

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Thermal expansion and transformation behavior of cerium and plutonium alloys: an application of the Aptekar–Ponyatovsky regular solution model

Lawson¹,

Lashley²

2011

J. Phys.: Condens. Matter

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In this paper we apply the Aptekar-Ponyatovsky (AP) regular solution thermodynamic model to the analysis of experimental data for the coefficient of thermal expansion (CTE) and determine the AP model parameters for unalloyed cerium metal, Ce-Th-La alloys, and Pu-Ga alloys. We find that the high temperature CTE of cerium metal follows the predictions of the AP model based on low temperature, high pressure data. For Ce-Th-La alloys we use the AP parameters to track the suppression of the first-order γ-α cerium transition. We show the AP model accounts for the negative CTE observed for Pu-Ga alloys and is equivalent to an earlier invar model. Finally, we apply the AP parameters obtained for Pu-Ga alloys to rationalize the observed δ-α transformation pressures of these alloys. We show that the anomalous values of the Grüneisen and Grüneisen-Anderson parameters are important features of the thermal properties of plutonium. A strong analogy between the properties of plutonium and cerium is confirmed.

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Section: Introductionmentioning

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Thermal expansion and transformation behavior of cerium and plutonium alloys: an application of the Aptekar–Ponyatovsky regular solution model

Lawson¹,

Lashley²

2011

J. Phys.: Condens. Matter

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“…Further experimental work on the thermal expansion of alloy-stabilized y-U would be revealing. Further work is needed also on y-Ce, for which an invar effect (not anti-invar) is predicted by the A-P model [27,28].…”

Section: Discussionmentioning

confidence: 99%

Physics of the Lindemann melting rule

Lawson

2009

Philosophical Magazine

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We investigate the thermodynamics of melting for 74 distinct chemical elements including several actinides and rare earths. We find that the observed melting points are consistent with a linear relationship between the correlation entropy of the liquid and the GrUneisen constant of the solid, and that the Lindemann rule is well obeyed for the elements with simple structures and less well obeyed for the less symmetric more open structures. No special assumptions are required to explain the melting points of the rare earths or light actinides.

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“…The mean hardness values were 0.28 GPa (Ce-3La), 0.30 GPa (Ce-5La) and 0.28 GPa (Ce-10La). The contact modulus (Er) was also determined using the two-slope method, the expression for which is given below: (4) Where β is an indenter geometry shape factor (1.034 in this study) and γ is a constant that accounts for deviations from the ideal Sneddon flat punch behaviour [37]; in this study a value of 1.06 [34] was used. The Er values are also listed in Table 3.…”

Section: Nanoindentationmentioning

confidence: 99%

“…Owing to the similarities between cerium (Ce) and delta-phase plutonium (δ-Pu) alloys, the former is considered as a non-radioactive surrogate for the latter [1][2][3][4][5][6]. These similarities include: (i) similar crystal structure (both being face-centred cubic at ambient temperature and pressure); (ii) relatively low melting temperature; and (iii) a tendency to transform to a different phase if cooled to sub-ambient temperatures or subjected to pressure [7,8].…”

Section: Introductionmentioning

confidence: 99%