We discovered a novel compound expressed by R(2)(Fe, M)(17+delta) in t
he compositional range between 2-17 and 1-12. Hong-Shou Li et al. repo
rted R(2)(Fe, M)(29) which is stoichiometric compound with monoclinic
structure. These compounds show similar X-ray diffraction patterns. In
this paper, syntheses of R(2)(Fe, M)(17+delta) were attempted for var
ious rare earth elements, R and transition metals, M, and their crysta
l structure and magnetic properties were investigated. It was found th
at nonstoichiometric compound, R(2)(Fe, M)(17+delta) (delta=1.0-4.0) f
orms for R=Ce,Nd,Sm,Gd,Dy,Y and M=Ti,V,Mo,W. X-ray and electron beam d
iffraction analyses revealed that the compound has hexagonal structure
with the space group of <P(6)over bar>2m. The nonstoichiometry of the
compound can be attributed to the diversity in the atom orders in the
c-planes. The saturation magnetization of R(2)(Fe,M)(17+delta) is ind
ependent of the kind of M-metals, however curie temperature changes as
315K(Mo), 333K(Ti), 342K(W) and 390K(V), which is similar tendency to
R(Fe,M)(32) compounds. For R(2)(Fe,M)(17+delta) the saturation magnet
ization and curie temperature show a maximum value for Nd(126 x 10(-6)
Wb . mkg(-1)) and Gd(541K) in the rare earth series, respectively.