Crystal structure of a new UGa2 phase

Crystal structure and electronic properties of new uranium intermetallic compound UGa1.85Zr0.15

“…The Zr content determined from X-ray diffraction (with relatively large error) corresponds to UGa 1.73(0.09) Zr 0.23(0.10) . This structure is also isostructural to the one identified in the vicinity of UGa 2 already for the pure U-Ga binary compound [9], forming with slightly smaller lattice parameters than the present variant with Zr. Both can be derived from U 3 Ga 5 [10].…”

Experimental investigation of the phase equilibria and thermodynamic assessment in the U-Ga and U-Al-Ga systems

“…The eutectic composition at the U-rich side is estimated at 76 at.% U, slightly poorer than the reported 78 at.% U value [15]. The as-cast samples in the composition range U 3 Ga 5 -UGa 2 were found systematically biphasic, composed of U 3 Ga 5 with the Pu 3 Pd 5 -type and of UGa 2 with the AlB 2 -type, ruling out the assumption of a solid solution at high temperature [21].…”

“…It crystallizes with the hexagonal AlB 2 type of structure as suggested by Buschow [15] and confirmed by [17] at least down to 80 K, a temperature at which a hexagonal to orthorhombic transition associated to magnetic ordering is supposed to occur [20]. More recently, it has been proposed [21] for UGa 2 a new crystal structure based on the Pu 3 Pd 5 prototype, which is stable at high temperature only. In addition, it is suggested that therefore, a continuous solid solution could exists between UGa 2 and U 3 Ga 5 compositions, but without further evidence about the phase relationships and transition temperatures [21].…”

“…More recently, it has been proposed [21] for UGa 2 a new crystal structure based on the Pu 3 Pd 5 prototype, which is stable at high temperature only. In addition, it is suggested that therefore, a continuous solid solution could exists between UGa 2 and U 3 Ga 5 compositions, but without further evidence about the phase relationships and transition temperatures [21]. This assumption is in disagreement with the DTA measurements [15], which does not show any transition below the congruent melting of UGa 2 estimated at 1628 K and the crystallographic analysis of a single crystal directly grown from the melt which shows the AlB 2 type of structure [22].…”

Aluminium, gallium, indium and thallium

“…Ga metal continues to find use as a solvent, or flux, for synthesis of new intermetallics, some not even containing Ga. 114 However a new gallide UGa 2 was synthesized by arc-melting of Ga on U. 115 GaN, well-established as a technological material, found other uses last year. In combination with Li 3 N it forms Li 3 N 2 Ga, a potential hydrogen storage material which reacts with 3.4% of its own mass of hydrogen, of which half is released under reduced pressure.…”