Magnetic properties of La3Ni2SbxTayNb1–x–yO9; from relaxor to spin glass

Abstract Neutron diffraction experiments conducted at 5 K in a magnetic field 0 ≤  H /kOe ≤50 have shown that the monoclinic perovskite La 3 Ni 2 TaO 9 behaves as a relaxor ferromagnet. Compositions in the series La 3 Ni 2 Sb x Ta y Nb 1– x – y O 9 have been synthesized in polycrystalline form. Electron microscopy, X–ray diffraction and neutron diffraction have shown that the solid solutions are largely homogeneous and monophasic. Magnetometry and neutron diffraction have shown that the relaxor magnetisation persists in low fields when x  +  y  = 1 but is rapidly diminished by the introduction of niobium. This change in magnetic behaviour is ascribed to the differences in the d –orbital energies of Sb 5+ , Nb 5+ and Ta 5+ .