155Gd Mössbauer effect studies and magnetic properties of GdFe 12− xMo x(N y) compounds

Abstract

Structural and magnetic properties of the GdFe 12− x Mo x compounds having the ThMn 12 type of structure were studied. Rare-earth nitrides of the composition GdFe 12− x Mo x N y were prepared by the reaction of GdFe 12− x Mo x with nitrogen gas at 475°C. The crystal structure and lattice constants have been determined for all compounds. The lattice expansion of the nitrogenated compounds is mainly along the a-axis, the Curie temperatures are increased by about 110 K. We investigated the effect of interstitial nitrogen on the magnetic properties and the 155Gd Mössbauer spectrum of GdFe 12− x Mo x . Values of the electric field gradient V zz derived from the quadrupole splitting of the spectra were strongly negative, with V zz = −21.3 × 10 21 V m −2 and V zz = − 19.9 × 10 21 V m −2 for x = 1.5 and 3.0, respectively. Nitrogenation is shown to lead to a sign reversal of the 4f as well as of the 3d sublattice anisotropies.