Influence of doping elements (Y, Fe, V) on magnetic properties of RM2 (R = Gd, Er; M = Fe, Co, Ni) Laves phases and their hydrides

The ternary R0.85Y0.15Ni2, RNi1.85Fe0.15 (R = Gd and Er), ErM1.85V0.15 (M=Fe, Co) and Er(Fe,Co)1.85V0.15 phases have been investigated for the influence of doping elements (Y, Fe, V) on magnetic properties of RM2 (R = Gd, Er; M = Fe, Co, Ni) Laves phases and their hydrides. All investigated compounds can easily absorb hydrogen up to 3.3-3.9 at.H/f.u. at 0.1-0.12 MPa pressure without amorphization. The hydrides preserve the structure of the parent compounds. Rare earth substitution of Gd and Er by 5 at. % Y in RNi2 based compounds reduces slightly both the ordering temperature and the magnetic moment due to the dilution effect of a magnetic rare earth element by a nonmagnetic one. The corresponding 3d metal substitution of Ni by 5 at. % Fe increases TC by a factor of 3-7 for Gd and Er, respectively. Er(Fe,Co,V)2 compounds with a Fe content higher than 20 at. % exhibit ordering temperatures above room temperature. Hydrogen absorption reduces the saturation moment and suppresses long range magnetic order in majority of investigated alloys to the temperature below 2 K except for ErFe1.85V0.15H3.9 and ErFe0.925Co0.925V0.15H3.6.