Study on Intrinsic Magnetostriction and Structure Properties of Rare Earth Intermetallic Laves Phase Compouds Containing Pr

Study on Intrinsic Magnetostriction and Structure Properties of Rare Earth Intermetallic Laves Phase Compouds Containing Pr
　　The research and exploiture of rare earth giant magnetostriction material are of great significance and value for national defense and high technology industry, and both application and market prospect of it are highly capacious in the future. Recently, many efforts have been focused on the investigation of the pseudo-binary rare earth intermetallic compounds (RFe2type Laves phase structure). As a light rare earth element, Pr has a large contribution to the magnetostriction in this Ball Neodymium Magnets kind of material, and its price is relatively lower. But the atomic radius of Pr is so large that PrFe2 can not be synthesized successfully at ambient pressure. The Laves phase giant magnetostriction compounds synthesized at ordinary condition usually have a low content of Pr. It is of great research value to increase the concentration of Pr in this kind of compounds without debasing the magnetostriction and structure properties.
　　In this thesis, five series of Laves phase compounds containing Pr have been studied by x-ray diffraction, VSM and standard strain gauge method, specially focused on the intrinsic magnetostriction and structure properties, supplying direction and aid for further study and application.When a small amount of Tb is replaced by Pr in PrxTb1-xFe1.9 compounds, no intrinsic structure changes for the Laves phase structure. The intrinsic magnetostriction,λ111 is about 2470ppm, still very large when x≤0.2.And this implies high application potential. But when x>0.2, the secondary phase (PuNi3) comes out, and there is also a little rare earth rich phase coming out. And the,λ111 is debased by these non Laves phases. The Pr concentration in the Laves phase compounds increases in Ball Neodymium Magnets condition of adding a small quantity of B atoms or partly replacing Fe by Co. The intrinsic magnetostrictionλ111 debases with more Ce substituting for Tb in Pr0.1CexTb0.9-xFe1.9.With more Pr substituting for Tb in multi-crystal PrxTb1-xFe1.9 compounds, the magnetostriction (λ∥-λ⊥) and the saturated magnetization (Ms) decrease gradually, while the lattice constant and the coercivity (Hci) increase gradually. The tendency of lattice constants follows Vegard Law.
　　The saturated magnetization (Ms) of PrFe1.9 at room temperature is 4.58μB per formula unit, deduced by linear fit.The study of Pr0.15Tb0.85Fe1.9Bx compounds indicates that the material has a large magnetostrictionλ111 when X<0.3. http://www.chinamagnets.biz/ The small B atoms prefer to occupy the interspace sites between lattice points and this makes lattice constant a little larger. With increasing more B content, they begin to compete with Fe to occupy the lattice sites after B content exceeding certain solubility, this makes lattice constant a little smaller and meanwhile some rare earth-rich phases come out. The tendencies ofλ111measured by XRD and gauge stain method are coincidental with each other.