Фазовая диаграмма системы B-Pu

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B-Pu (Boron-Plutonium) P. Rogl and P.E. Potter With the exception of the identification of the binary compounds, little experimental data are available for the Pu-B system. Several similarities between the RE-boride systems have been observed, resulting in extrapolation of RE-B behavior to the Pu-B system. Thus, the assessed phase diagram is tentative in most parts. The diagram is characterized by the formation of five binary high melting compounds with very small homogeneous regions and with rather small mutual solid solubilities of the solid elements. The elemental transitions for Pu were taken from [86War]; those for B correspond to the data derived by [72Mar] and [73Hol]. "PuB" is not confirmed and is speculated to be either an impurity phase or an impurity-stabilized phase. The equilibrium phases of the Pu-B system are (1) the liquid, L; (2) the various polymorphic modifications of Pu metal, i.e., a, b, g, d, d›, and ePu, for which only a small solid solubility for B is estimated; (3) the Pu diboride; (4) the Pu tetraboride; (5) the Pu hexaboride; (6) the Pu dodecaboride; (7) the Pu hectoboride; and (8) a rather restricted solid solution of less than ~0.5 at.% Pu in b-rhombohedral B. According to [65Eic] and [88Rog], the borides form at the stoichiometric composition with rather limited homogeneous ranges of less than 1 at.% B. All compounds were found to exist in the entire temperature region investigated (800 C up to the melting range). PuB2 was said to be easily obtained at temperatures up to 1750 C [ 65Eic]. According to [75Smi], the magnetic susceptibility of PuB2, PuB4, and PuB6 is relatively temperature independent; however, the reported values appear somewhat limited due to the presence of secondary boride phases. 55Zac: W.H. Zachariasen and F.H. Ellinger, Acta Crystallogr., 8, 431-433 (1955) . 56Ell: F.H. Ellinger, Trans. AIME-J. Met., 8, 1256 (1956). 60Mcd: B.J. McDonald and W.I. Stuart, Acta Crystallogr., 13, 447-448 (1960). 63Zac1: W.H. Zachariasen and F.H. Ellinger, Acta Crystallogr., 16, 777-783 ( 1963). 63Zac2: W.H. Zachariasen and F.H. Ellinger, Acta Crystallogr., 16, 369-375 ( 1963). 64Ska: R.E. Skavdahl, T.D. Chikilla, and C.E. McNeilly, Trans. Am. Nucl. Soc., 7, 403-404 (1964). 65Eic: H.A. Eick, Inorg. Chem., 4(8), 1237-1239 (1965). 72Mar: R.W. Mar, Thermochim. Acta, 4, 367-376 (1972). 73Hol: C.E. Holcombe, D.D. Smith, J.D. Lore, W.K. Duerksen, and D.A. Carpenter, High-Temp. Sci., 5, 349-357 (1973). 75Smi: J.L. Smith and H.H. Hill, AIP Conf. Proc., 24, 382-384 (1975). 81Cre: A.J. Crespo, L.E. Tergenius, and T. Lundstr”m, J. Less-Common Met., 77, 147-150 (1981). 82Smi: J.L. Smith and Z. Fisk, J. Appl. Phys., 53(11), 7883-7886 (1982). 86Lar: J. Larroque, R. Chipaux, and M. Beauvy, J. Less-Common Met., 121, 487- 496 (1986). 86War: J.W. Ward, P.D. Kleinschmidt, and D.E. Peterson, Handbook of the Physics and Chemistry of the Actinides, Vol. 4, A.J. Freeman and C. Keller, Ed. , North-Holland Publishing, Amsterdam (1986). 87Chi: R. Chipaux, M. Beauvy, D. Bonisseau, and A. Blaise, paper presented at the 9th International Symposium on Boron, Borides and Related Compounds, 21-25 Sep 1987, Proceedings, H. Werheit, Ed., Universit„t Diusburg, BRG, 393-396 ( 1987); see also R. Chipaux, These de doctorat, Universit‚ d'Aix-Marseille, Oct 1987. 88Rog: P. Rogl and P.E. Potter, research at the UKAEA-Harwell Laboratory, 1988, to be published. Submitted to the APD Program. Complete evaluation contains 1 figure, 3 tables, and 28 references. 1