Cooperative effects of a combined substitution on the magnetic properties of Nd2−xYxFe17−ySiy intermetallic compounds (⩽x⩽1.5,⩽y⩽3.0)

Abstract

The effects of a combined substitution of Nd by Y and Fe by Si in Nd2−xYxFe17−ySiy compounds (0⩽x⩽1.5,0⩽y⩽3.0) on structural and magnetic properties have been investigated by means of x-ray diffraction, neutron diffraction, and magnetic measurements. The investigated samples crystallize in Th2Zn17-type structure with only small amounts of alpha-Fe. The unit cell volume decreases with increasing Y content or Si content. Neutron diffraction analysis indicates that substitution of Y for Nd induces a decrease of Si occupancy in 18h sites and increases in 9d sites and 18f sites. With the substitution of Y for Nd, the average site bond lengths in 6c, 9d, 18f, and 18h sites all decrease, but the distances of all Fe-Fe pairs do not change negatively. The TC of Nd2−xYxFe17−ySiy increases significantly with increasing Si substitution (y⩽3.0), but it changes slightly with increasing Y substitution. Similar to the case of Si substitution, the Ms also first increases and then decreases with increasing Y substitution. The highest TC of 535K and the highest Ms of 121.1emu∕g were observed in Nd1.5Y0.5Fe14.0Si3.0 and Nd1.5Y0.5Fe15.0Si2.0, respectively, which indicates that the combined substitution of Nd by Y and Fe by Si can have a strongly cooperative effect on the improvements of magnetic properties.

Thermal expansion anomaly and magnetostriction of Nd2Fe14Si3 intermetallic compound

“…X-ray diffraction of R 2 Fe 14 Si 3 compounds indicate that the prepared samples to be almost single phase that crystallize in rhombohedral structure of Th 2 Zn 17 -type, however, a few percent of alpha iron were observed as a second phase in Nd 2 Fe 14 Si 3 sample. The presence of such impurity phase has also been reported in earlier publications [22,23]. The lattice parameters are found to be a = 8.443 Å, c = 12.434 Å and a = 8.512 Å, c = 12.464 Å for R = Ce and Nd, respectively.…”

“…It is well known that in R-Fe compounds, there are three exchange interactions included J FeFe between the Fe spins, J RFe between the rare earth spin and Fe spins, and J RR between rare earth spins. J FeFe is dominant in comparison to J RFe , whereas J RR contribution is small and can be neglected [22]. Therefore, J FeFe has the major contribution to x s in these compounds.…”

“…Therefore, the magnetic moments, the bond lengths and the effective number Fig. 3, using the Neutron diffraction measurements on these compounds [22,[26][27][28]. The anomalous thermal expansion and Invar effect in R 2 Fe 17 -type below room temperature is due to the negative magnetic interaction between the 6c-6c, 9d-18f, and 9d-18h sites [5].…”

Crystallographic structure and magnetic properties of NdyDy1−yFe11−xTiCox compounds

“…Hu). stitution of suitable elements for Fe [9][10][11], the substitution of different rare earth element [12,13] or the combination of several techniques [14,15]. It is believed that the substitution can modify the crystallographic structure and modulate more bond lengths into the optimum ferromagnetic exchange distance range, which leads to the improvements of magnetic properties.…”

Influence of process-induced stress on multiferroic properties of pulse laser deposited Bi0.7Dy0.3FeO3 thin films

“…The x-ray powder diffraction study and the preliminary analysis of neutron diffraction data obtained for the Bi 0.7 Dy 0.3 FeO 3 bulk sample have indicated a decrease in the unit cell volume (∼6%) and a reduction in the Fe-Fe and Bi-Fe bond lengths with the removal of La from the system. This could be the reason for enhancement in the magnetization value [9]. However, a further detailed analysis is currently in progress to find out possible reordering of the cations in the system which could also bring about enhancement in the magnetic properties [10].…”