Hydrogen In U-T Alloys: Crystal Structure And Magnetism Of Uh3-V

U-V alloys with variable phase composition were prepared using ultrafast cooling. 15 at.% V is not sufficient to suppress entirely the orthorhombic alpha-U type of phase and higher alloying concentrations lead to a segregation of pure vanadium. The alloys are stable with respect to H-2 exposure at pressures of 10(5) Pa. Nevertheless hydrogenation proceeds slowly at high H-2 pressures. Resulting hydrides exhibit a common beta-UH3 structure. This is unusual among the U-T systems, which yield either alpha-UH3 or nano-crystalline beta-UH3 structures. The UH3-V system is ferromagnetic with the Curie temperatures monotonously increasing with the V concentration to T-C = 190 K for 15 at.% V. Magnetic moments remain on the level of 1.0 mB/U. The results prove that the increase of T-C in alloyed U hydrides of the UH3-T type does not depend on particular structure details or type of the T element, although the latter modifies somewhat the maximum T-C values achieved. The situation can be understood assuming that the substitution of U by T provides an enhanced H/U ratio, while the U-H interaction is a prominent element of the 5f moments formation and ordering. (C) 2020 Elsevier B.V. All rights reserved.