Evolution of the magnetic behavior of the Co subsystem in YCo3 caused by small variations in stoichiometry and Al substitution

The phase composition at room temperature and the magnetization up to 55 kOe over the temperature interval 5-400 K for polycrystalline compounds YCo3+delta (- 0.18 less than or equal to delta less than or equal to 0.24) and Y(Co1-xAlx)(2.92) (x less than or equal to 0.1) were studied. It was found that a homogeneous rhombohedral PuNi3-type structure is formed within the Co concentration interval -0.14 less than or equal to delta < -0.08. The magnetic ordering temperature, magnetization at 5.5 T, and the lattice parameters of YCo2.88, were determined to be 260+/-2 K, 0.46+/-0.3 mu(B)/Co and a = 5.02 Angstrom, c = 24.38 Angstrom (hexagonal set), respectively. The nonlinear variation of T-C vs. Al concentration was ascribed to the composition dependence of the Co magnetic moment. (C) 2000 Elsevier Science S.A. All rights reserved.