Study On Structure And Magnetic Properties Of Rare Earth Transition Metal Intermetallic Compounds Of Nd_3-xPr_xFe_29-yTi_y ?y=2,1.3?x?1.8?

The NdPr2Fe29-xTix (1.3?x?1.8) compounds were prepared by the Vacuum arc melting technique and high temperature (1373K) annealing. The crystal structure of the compounds was determined by XRD, the saturation magnetization, anisotropy field and the Curie temperature were obtained by magnetic measurement. And the thermo-magnetic properties of the compounds were characterized by Differential Scanning Calorimeter (DSC). (1) XRD characterization indicate that the crystal structure of NdPr2Fe29-xTix is 3:29 type Nd3(Fe, Ti)29 structure in monoclinic with space group of A2/m. The volume on the cell marginally decreases with the increasing Ti concentration. Structural characterization also indicates that the sample prepared in current work contains small amount of ?-Fe. XRD characterized of normal oriented sample demonstrates that the compounds have an axial magnetic anisotropy. (2) magnetic measurements shows that the anisotropy field Ba of NdPr2Fe29-xTix compounds decreases monotonically with the increasing Ti content. The saturation magnetization of the compounds also merely decreases with the increment of Ti concentration, and Ms also decrease for increasing temperature. An exceptional finding is that Ms experiences a sudden decrease at y=1.4, which could be attributed to the small amount of second phase. (3) DSC curve shows that increasing Ti content could obviously increase the vibrational heat capacity, while have no measurable effect on the Curie temperature of the compounds. Namely, addition of Ti does not have significant effect on the exchange interactions between transition metals (i.e. Fe-Ti and Fe-Fe) and transition metals and rare earth elements. One interesting results is that the ferromagnetic to paramagnetic transition temperature obtained from DSC is about 330 K, while magnetic measurement gives a 410 K for NdPr2Fe29-xTix compounds, this large discrepancy would be clarified in the further work.