A cubic AuBe5-type YbCu5 phase with trivalent Yb ion

Abstract The cubic YbCu 5 compound with the AuBe 5 -type structure was prepared for the first time under a pressure of 1.5 GPa and annealed at 650°C. The previously reported hexagonal YbCu 5 phase with the CaCu 5 -type structure was also confirmed to be stable under relatively lower pressure and at higher temperature. In contrast to the divalent non-magnetic state of Yb ion in the hexagonal phase. Yb ion in the cubic phase was found to be in the trivalent magnetic state. The cubic YbCu 5 phase probably presents a reasonable conjunction for a family of isostructural YbCu 5 , M 1 (M = In, Ag, etc.) compounds, both in crystallographic aspect and in physical properties.