Thallium alloys of the rare earth: Sm\uf8ffTI Phase diagram and molar volumes of the rare earth thallides

The Sm\uf8ffTl system has been studied by differential thermal, metallographic and X\u2010ray analyses. The following intermediate phases were observed: Sm2Tl (decomposes at 1030 \ub1 10\ub0C); Sm5Tl3 (decomposes at 1060 \ub1 10\ub0C); SmTl (melting point, 1220 \ub1 20\ub0C); Sm3Tl5 (decomposes at 940 \ub1 10\ub0C); SmTl3 (melting point, 870 \ub1 5\ub0C). Three eutectics occur: \u3b2\u2010Sm\u2014Sm2Tl (840 \ub1 10\ub0C, 18.0 \ub1 0.5 at % Tl); Sm3Tl5\u2014SmTl3 (860 \ub1 5\ub0C, 72.0 \ub1 0.5 at % Tl); SmTl3\u2014\u3b2\u2010Tl ( 3c303\ub0C, greater than 99.5 at % Tl); there is an eutectoidal reaction at 760 \ub1 10\ub0C and 10 \ub1 1 at % Tl (decomposition of \u3b2\u2010Sm phase). Following crystal structures have been determined or confirmed: Sm2Tl hexagonal hP6\u2014Ni2In\u2010type, Sm5Tl3 tetragonal tI32\u2014W5Si3\u2010type, SmTl cubic cI2\u2014W or cP2\u2014CsCl\u2010type, SmTl tetragonal tP4\u2014AuCu I\u2010type, Sm3Tl5 orthorhombic oC32\u2014Pu3Pd5 like\u2010type, SmTl3 cubic cP4\u2014AuCu3\u2010type. The characteristics of the phase diagram and the molar volumes of the Sm\uf8ffTl compounds are compared with those of other RE\uf8ffTl alloys and briefly discussed. Copyright \ua9 1983 Verlag GmbH & Co. KGaA, Weinhei