Studies On Structure And Magnetostriction Of Light Rare Earth Compounds With Laves Phase

In this paper, the Giant Magnetostrictive Materials with light rare earth have been fabricated in an arc-melting furnace. Structure, magnetic properties and magnetostriction have been investigated with XRD, a.c. susceptibility, Vibrating Sample Magnetometer and standard strain gauge techniques.The properties of (PrCeTb)Fe1.9 compounds have been greatly influenced by the valence fluctuation of Ce ions. The lattice parameter shows positive deviation from Vegard's law; Curie temperature decreases with Ce content increasing; magnetostriction increases abnormally in specifically rangs of Ce content due to the contribution of Ce ions fluctuation towards localized state (+3). According to the analysis of structure, magnetic properties and magnetostriction, the valence of Ce ions fluctuates towards localized state due to the substitution of Ce for Tb in (PrCeTb)Fe1 9 compounds.When x≤0.1, the lattice parameter of Pr₀.1Ce₀.6Tb₀.3Fe_1.9-xB_x compounds decrease slightly because some B atoms occupies the initial sites in the crystal lattice; Curie temperature increases with B content increasing. When x>0.1, the lattice parameter decreases rapidly due to the substitution of B atoms for Fe atoms; Curie temperature decreases sharply. The lattice parameter of Pr₀.1Ce₀.6Tb₀.3Fe₁.9B_X compounds increases with Ce content increasing; Curie temperature increases when x≤0.1, and decreases when x>0.I. In the two series compounds, the magnetostriction decreases, and the valence fluctuation of Ce ions has not been observed.The studies on (PrTbDy)(FeM)2 (M=Ni, Si, Mn) alloys show the effects of M substitution for Fe. The substitution of Ni and Si for Fe makes lattice parameter, Curie temperature, satuation magnetization and magnetostriction decreasing. It is found that the Si content should be limited in 0.2, otherwise other unwanted phases will appear when x>0.2. The substitution of Mn for Fe induces the lattice parameter increasing, and Curie temperature decreasing. The magnetostrictionat room temperature shows the optimal value when Mn content is 0.1. The magnetostriction of Pr₀.1Tb₀.3Dy₀.6Fe₁.9Mn₀.1 alloy increases with compressive stress increasing at high magnetic fields. Pr₀.1Tb₀.3Dy₀.6Fe₁.9Mn₀ 1 alloy exhibits good magnetostrictive properties at low magnetic fields when compressive stress is less than 16MPa.The studies on Pr₀.15Tb₀.30Dy₀.55Fe₁.85C_x alloys show that all the samples exhibit a perfect single phase with Laves phase structure. The lattice parameter increases with C content increasing due to the initial C atoms; Curie temperature increases linearly with C content increasing; the magnetostriction at high magnetic fields shows a peak at x=0.05.