| The RFe10.5-xMnxMo1.5 (Sm, Nd, Y, Tb, Ho) compounds are prepared by means of vacuum arc melting, subsequent vacuum annealing, then some of which are carried out by nitriding. The influence of the substitution of Mn for Fe and nitriding on the structure and magnetic properties of these compounds are investigated by X-ray powder diffraction and magnetic measurements.It is found that the structure of RFe10.5-xMnxMo1.5(Sm, Y, Tb, Ho) compounds is of a single phase with tetragonal ThMn12-type structure in a wide Mn concentration range. The substitution of Mn for Fe in RFe10.5-xMnxMo1.5 compounds causes a rapid decrease of the Curie temperature of the compounds and the magnetic moment of the transition-metal sublattice. The saturation magnetization of RFe10.5-xMnxMo1.5(R=Y, Sm) compounds decrease monotoically with increasing Mn concentration, and which of RFe10.5-xMnxMo1.5 (R=Tb, Ho) compounds decrease at first and then increase with increasing Mn concentration, and the magnetic moments of Mn-Fe and Mn-R sublattice are non-linear.The RFe6.5Mn4Mo1.5 (R= Nd, Y, Tb, Ho) compounds and their nitrides show that all samples are in tetragonal ThMn12-type structure. The lattice constants and the unit-cell volumes decrease from Y to Ho in RFe6.5Mn4Mo1.5 (R= Nd, Y, Tb, Ho) compounds. Upon nitrogenation, the unit-cell volume and the Curie temperature of these compounds rise markedly compared to their original counterparts. But the saturation magnetizations of these nitrides are varied non-regularly. An obvious feature is the occurrence of compensation points in the magnetization-temperature curves of TbFe7.5Mn3Mo1.5, TbFe7.5Mn3Mo1.5Ny, and HoFe7.5Mn3Mo1.5Ny samples, and these compensation temperatures are about 72 K, 88 K, and 50 K, respectively. The compensation points with zero moment are observed in the magnetization-temperatures curves of HoFe10.5-xMnxMo1.5 compounds with x=2.0 and x=3.0, and these compensation temperatures are about 35K, 54 K, and 10 K, respectively.
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