A Study Of Structure And Magnetic Properties Of The SmFe_12-xNb_X Rare Earth Compounds

The series of SmFe_12-xNbx,SmFe_11.25-xCo_xNb_0.75and Er₃Fe_28.2-xNi_xNb_0.8compoundshave been prepared by vacuum arc melting method and the orientation samples of thecorresponding compounds were prepared with the method of grinding bond. TheX-ray diffraction has been used to analysis of the lattice structure of the variouscompounds, and use X ’Pert Plus software to make X-ray diffraction peak data of freepowder samples and oriented samples to fit on each sample to determine the latticeconstant and magnetic anisotropy. With the help of differential scanning calorimetoryand vibrating sample magnetometer, the author measured and determined the Curietemperature of each sample and analyze the cause and mechanism of the relatedphenomenon. The hysteresis loop of each sample of SmFe_12-xNbxseries andSmFe_11.25-xCo_xNb_0.75series compounds have been measured using a vibrating samplemagnetometer, and then the author calculated the coercivity of each sample andanalyzed the rules and reason for specific changes. The work mainly includes:For the SmFe_12-xNbxand SmFe_11.25-xCo_xNb_0.75two series of compounds, the XRDshows that their lattice structure are1:12-type tetragonal ThMn12structure withI4/mmm space group. Each sample has a small amount of α-Fe phase as impurity; dueto geometric factors,with the increase of niobium （Nb） content, the latticeconstants and cell volume of SmFe_12-xNbxseries of compounds are monotonouslyincrease. With the Co content increases SmFe_11.25-xCo_xNb0.7series compounds, thelattice constant decreases monotonously, and the unit cell volume contracts; The twoseries of compounds exhibit the uniaxial anisotropy at room temperature; because themechanism of exchange interaction and exchange coupling of magnetic dipole isdifferent with the ratio change x, the reasons why the Curie temperaturemonotonously increase and coercivity monotonously reduce with increasing x arediscessed.In addition, a3:29type compounds Er₃Fe_28.2-xNi_xNb_0.8with P63/mmc space grouphave been investagated. The lattice constant and the unit-cell volume of thecompounds decreases linearly with increasing Ni content. Curie temperature linearlyincreases and the compounds shows plane magnetic anisotropy at room temperature.