Formation, structural and magnetic properties of Gd3(Co,Cr)29 compounds

Abstract

Co-based Gd3Co29−xCrx compounds with a Nd3(Fe,Ti)29-type of structure have been synthesized successfully for x=6.5 and 7.0. The crystal structure and magnetic properties of the Gd3Co29−xCrx compounds have been investigated by x-ray diffraction analysis and magnetic measurements. It has been found that Gd3(Co,Cr)29 with x=6.5 and 7.0 are of ferrimagnetic compounds with Curie temperature of 412 K for x=6.5 and 359 K for x=7.0, respectively. Temperature dependence of the magnetization shows a compensation point of the magnetization at the certain temperature below the Curie temperature. The intersublattice molecular field coefficient, nRT, was derived to be 3.3 T f.u./μB for Gd3Co22.5Cr6.5 on the basis of the magnetization curve at the compensation temperature. It is noteworthy that the Gd3(Co,Cr)29 compounds exhibit favorable easy-axis anisotropy in the whole temperature range below Curie temperature.

Atomistic investigation on site preference and lattice vibrations of Sm(Co,M)12 (M = Cr, Ti, V, Nb, Fe)

“…The calculated results are listed in Table 2, together with the experimental data [22,23]. From Table 2, one can see that our results for Sm(Co,M) 12 are in agreement with experiment.…”

“…In order to check the structural stability at high temperature, the high temperature disturbance is used with molecular dynamics. The constant-NPT molecular dynamics is applied using the method of Berendsen et al [24] for 10,000 steps, with P = 1 atm, t = 0.001 ps, dynamic simulation for SmCo 10.14 Ti 1.86 is carried out at temperatures of 300, 500 and 700 K. After Table 2 Comparison between the experimental [22,23] reaching equilibrium, the crystal symmetry can be identified as I4/mmm space group in a certain range, and the lattice constants change little with respect to the temperature (Table 2). Thus, the structural stability is again verified.…”

Formation, structure and magnetic properties of Nd3Fe26.8 xCoxV2.2compounds

“…It is found that in Nd 3 (Fe,Ti) 29 -type compounds the magnetocrystalline anisotropy contribution resulting from the Fe-sublattice is along the [40−2] direction ([110] direction in 1 : 5 structure), the contribution resulting from Nd is along the [040] direction ([1−10] direction in 1 : 5 structure) [16] and the contribution resulting from Co is along the [204] direction ([001] direction in 1 : 5 structure) [12]. On increasing the content of Co the easy-plan-type anisotropy resulting from the Fe-sublattice decreases, which leads to an increase in T sr .…”

“…In order to investigate the room temperature magnetocrystalline anisotropy of the compounds, the XRD patterns of [11,12], where the anisotropy at room temperature is dependent on the content of Co and has an easy-axis-type anisotropy for x 10. It is well known that in the R-T compounds there exist three exchange interactions: the R-R interactions between the R magnetic moments within the R sublattice, the T-T exchange interactions between the T magnetic moments within the T sublattice and the R-T interactions between the R moments and T moments.…”

“…Yang et al [10] have synthesized Sm 3 (Fe,Ti) 29 N y compounds that exhibit outstanding intrinsic permanent magnetic properties. Subsequently, Yang et al [11] and Wang et al [12] have synthesized Gd 3 Fe 29−x−y Co x Cr y compounds with the substitution of Co for Fe and found that Gd 3 (Fe 1−x Co x ) 25 Cr 4 compounds show a room temperature uniaxial magnetocrystalline anisotropy for x 0.4, which is important for application as permanent materials. These results indicated a prospective application of the noninterstitial R 3 M 29−x T x compounds as permanent magnetic materials.…”