A Study Of Structure And Magnetic Properties Of The Nd₃Fe_27.7-xNi_xTi_1.3 Rare Earth Compounds

A series of Nd₃Fe_27.7-xNi_xTi_1.3 compounds have been studied by means of X-Ray diffraction and magnetic measurement in concentration range 0.2≤x≤1.2 shown all of the compounds crystallize in Nd₃(Fe,Ti)₂₉-type structure with monoclinic symmetry of A2/m space group and all of the compounds coexist with a little ofα-Fe phase and 1:12 phase or 2:17 phase as a second phase. The lattice parameters and the unit cell volume decreases slightly with increasing Ni content. The X-ray diffraction patterns of the aligned powder of the samples have confirmed that all of compounds at room temperature have planer anisotropy. It can be seen from the thermomagnetic analyses that the Curie temperature TC of the compounds increase monotonically with increasing the concentration x, but the spin reorientation temperature Tsr not change almost. The M - B curves measured in low temperature show that the saturation magnetization Ms of the compounds decreases monotonously with increasing Ni content. On the other hand, it is found that the extremum of the anisotropy fields Ba and the anisotropy contant K1 and K2 occure at x = 0.6.Two series of 2:17 phase compounds (Y₂Co_15.24-x FexCr_1.76(x = 2 - 8) and Nd₂Co_{17- x} Cr_x(x= 1.17 - 3.0)) were studied by the same method, and their structure and magnetic properties were investigated by X-ray diffraction and magnetization measurements.A study on the Y₂Co_15.24-xFe_xCr_1.76(x = 2 - 8) compounds show that the lattice parameters and the unit cell volume monotonously increases with increasing Fe content. The X-ray diffraction patterns of the aligned powder of samples have confirmed that at room temperature the compounds with x = 2 - 6 have uniaxial anisotropy, but the compound with x = 8 has planar anisotropy. The thermomagnetic curves shown that the Curie temperature TC monotonously decreases with increasing Fe content and the spin reorientation phenomena is observed for x = 8. The M - B curves measured with SQUID shown that the spontaneous magnetization M0 and the saturation magnetization Ms at different temperature increase with increasing Fe content respectively. The M0 and the Ms of the compounds decrease monotonously while increasing temperature from 5 K to 305 K. The maximum value of the anisotropy fields Ba appeared for x = 6 at 5 K and 305 K. The anisotropy content K1 and K2 of Y2Co7.24 Fe8Cr1.76 compound, the former is almost linear increase and further is almost linear decrease with increasing temperature from 5 K to 305 K.All of Nd2Co17-xCrx(x = 1.17 - 3.0) compounds have crystallized in rhombohedral Th2Zn17-type structure and coexist with a little of 1:12 phase. The lattice parameters and the unit cell volume slightly increases with increasing Cr content. The X-ray diffraction patterns of the aligned powder of samples have confirmed that all of compounds have planer anisotropy at room temperature. The spin reorientation phenomena is observed and the spin reorientation temperature Tsr decreaes strongly in the range x from 1.17 to 2.34. The Curie temperature of the compounds decreases with increasing Cr concentration.