Structure and magnetic properties of Er3(Fe, Co, M)29 compounds (M = Cr, V, Ti, Mn, Ga, Nb)

A series of Er-3 ( Fe, Co, M)(29) ( M = Cr, V, Ti, Mn, Ga, Nb) compounds has been synthesized and their structure and magnetic properties have been investigates by means of x-ray diffraction and magnetic measurements. It is found that the Fe-based Er-3 ( Fe, M)(29) compounds crystallize in the Th-2 Ni-17-type structure with disordered substitution of the dumbbell Fe-Fe, instead of Nd-3 (Fe, Ti)(29)-type structure. so its chemical formula can also be expressed as Er2-n ( Fe, M)(17+2n) ( n = 0.2). Substitution of M for Fe in the Er-3 Fe-29 compound leads to an increase in the Curie temperature. With the substitution of Co for Fe in the Er-3 ( Fe, M)(29) ( M = Cr, V) compounds, a new phase was found which crystallizes in monoclinic symmetry. The anisotropy of the Er-3 Fe-19.5 Co-6 V-3.5 compound at room temperature is of easy-axis type and a spin reorientation transition from the easy-axis type to the easy-plane type anisotropy occurs when temperature decreases to 162K. A first order magnetization process (FOMP) was observed in the HMD magnetization curve of Er-3 Fe-19.5 Co-6 V-3.5 at 5K, the critical field of the FOMP was derived to be 3.8T.