| Spinel ferrite and rare-earth manganite are always the focus of attention by researchers due to the unique performance of the spinel ferrite and rare-earth manganite and low cost, which have been widely used in many field, including wastewater treatment, magnetic separation, ferrofluid, audio and video tapes, high density digital recording disk, catalyst, gas sensor, magnetic resonance imaging, target to drugs and energy storage, and promising materials for magnetic refrigeration. Material properties depend on the composition and the synthetic method, how preparing the spinel ferrites and rare-earth manganite with high performance via the simple synthesis method are key to achieve the application of the target product. To the best of our knowledge, spinel LixCo0.5Zn0.5-xFe204(0.0≤x≤0.3) and LixCu0.6Mg0.4-xFe2O4(0.0≤x≤0.3) ferrites were synthesized by the thermal decomposition of oxalates, and La0.67Ca0.33Mn1-xNix03(0.0≤x≤0.3) carbonate precursor was synthesized by low temperature solid state reaction method at first, and then perovskite type manganite La0.67Ca0.33Mn1-xNixO3(0.0≤x≤0.3) was obtained by calcining the precursor at high temperature, which are rarely reported in the previous literature. So, in this paper, ferrites and rare-earth manganite are synthesized by thermal decomposition of oxalates and by low heating solid-state reaction method, respectively, and structure and properties of these materials were investigated. Precursor and calcined products were characterized by the thermogravimetric/differential scanning calorimetry, X-ray powder diffraction, scanning electron microscopy, and vibrating sample magnetometer. The results were obtained as follows:(1) Highly crystallized cubic LixCo0.5Zn0.5-xFe2O4 with approximately spherical morphology was obtained when LixCo0.5Zn0.5-xFe2O4 precursor was calcined at 900℃ in air for 3 h. The unit cell parameters of the sample decrease with the increase of the Li+content, attributed that the radius of the Li+ ion is smaller than that of the Zn2+ion. Substitution of Zn2+ion by Li+ion does not change the spinel structure of Co0.5Zn0.5Fe2O4. Magnetic properties of 204 depend on Li+content and calcination temperature. obtained at 900℃ had the highest specific saturation magnetization value (70.24 emu·g-1). However, Lio.3Co0.5Zn0.2Fe2O4 obtained at 800℃ had the highest remanence (8.29 emu·g-1) and coercivity (97.8 Oe) values.(2) Highly crystallized cubic LixCu0.6Mg0.4-xFe2O4 with irregular morphology was obtained when LixCu0.6Mg0.4-xFe2O4 precursor was calcined at 900℃ in air 3 h. The unit cell parameters of the sample decrease with the increase of the Li+content, which is attributed that the radius of the Li+ion is smaller than that of the Mg2+ion. The spinel structure of Co0.5Zn0.5Fe2O4 is not changed after the Mg2+ion is replaced by Li+ion. The lattice strain decreases with the increase of Li+content and/or the decrease of Mg2+content, which is attributed that the radius of Li+ion is smaller than that of Mg2+ion. Magnetic properties of LixCu0.6Mg0.4-xFe2O4 depend strongly on the composition and calcination temperature. Cuo.6Mgo.4Fe204 obtained at 900℃ had the highest specific saturation magnetization value (42.44 emu· g-1); remanence of Li0.2Cu0.6Mg0.2Fe2O4 obtained at 900℃ is approximately zero.(3) Highly crystallized orthorhombic La0.67Ca0.33Mn1-xNix03 (0≤x≤0.3) was obtained after calcining a mixture of carbonates in air above 800℃ 3 h. The substitution of manganese by nickel does not change the orthorhombic structure of La0.67Ca0.33Mn1-xNixO3. The crystallite diameter of La0.67Ca0.33Mn1-xNixO3 increases with the increase of Ni content. The lattice strain decreases with increasing Ni content. Nickel substitution can significantly improve specific magnetization of La0.67Ca0.33Mn1-xNixO3. Even at 293 K, the coercivity of La0.67Ca0.33Mn0.7Ni0.3O3 (9 Oe) was still higher, indicating that the material continues being ferromagnetic above 260 K (Curie temperature of LCMO). |
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