Magnetic properties of RENbF7 (RE  rare earth)

The magnetic properties of the series RENbF7 (RE  Ce, Pr, Nd, Gd, Dy, Ho, Er, Yb) were investigated. Magnetic susceptibility data were obtained on powdered samples at temperatures from 4.2 to 200 K. All compounds were found to be paramagnetic in this temperature range. Magnetization versus applied field curves for the materials with RE  Ce, Nd, Er, Yb could be fitted successfully to Brillouin functions with an effective spin of 12; for RE  Gd the expected free-ion behaviour was observed.The 70170Yb Mössbauer spectrum of YbNbF7 at 4.2 K showed a three-line pattern resulting from quadrupole interactions only. This observation is consistent with the absence of magnetic order at 4.2 K.Analysis of these data allows the conclusion that the ground state of the RE3+ ion in these materials is characterized by large admixtures of wavefunctions of the form ¦J, ± MJ(max)〉.