The X-ray and microhardness data on palladium-lutetium alloys containing $35$; $40,\!06$; $44,\!5$, and $45,\!7$ at.% Lu showed that, after annealing at $1000$$^о$C for $4$ h, the alloys contained not only the Pd$_3$Lu, Pd$_4$Lu$_3$, and PdLu equilibrium intermetallic compounds but also a variable-composition X-phase with a hexagonal lattice and the $c/a$ ratio ranging from 0.45 to 0.52. The X-phase occurs in a wide concentration range in the Pd-Lu system and can therefore be classified with intermetallic compounds of a special type called berthollides according to N.S. Kurnakov.
$^1$Department of Solid-State Physics, Faculty of Physics, Moscow State University, Leninskie Gory, Moscow, 119992, Russia
$^2$Mongolia
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