Effects of Nonmagnetic Zn 2+ Ion and RE Ion Substitution on the Magnetic Properties of Functional Nanomaterials Co 1-y Zn y RE x Fe 2-x O 4 (RE = La, Sm, Gd) by Sol-Gel.

Magnetic Functional Nanomaterials Co 1-y Zn y RE x Fe 2-x O 4 (RE (rare-earth) = La,Sm,Gd) were prepared using the sol-gel combustion method. XRD characterization confirms that the ferrite samples we synthesized are single-phase cubic structures. The variation in the average crystalline size and lattice parameter is related to RE ion doping. The Mössbauer spectra of CoRE x Fe 2-x O 4 are two sets of magnetic six-wire peaks that indicate the ferrimagnetic behavior of the sample. The calcination temperature greatly influences the absorption area of Mössbauer for CoFe 2 O 4 , indicating that the calcination temperature affects the iron ion content at the octahedral B and tetrahedral A sites. Additionally, scanning electron microscopy measurements of the substituted specimens reveal that the ferrite powders are nanoparticles. With an increase in RE ions, the coercivity increases, and the saturation magnetization changes obviously. The XRD characterization of Co 0.7 Zn 0.3 La x Fe 2-x O 4 shows that the main crystalline phase of the sample is the cubic spinel structure phase, and there are fewer secondary crystalline phases. The lattice parameter tends to decrease with the substitution of La 3+ ions. The average grain size decreased significantly with the increase in La content. From ferrimagnetic state transition to relaxation behavior, the hyperfine magnetic field decreases in La concentration by room temperature Mössbauer spectra. With the substitution of La 3+ ions, both the saturation magnetization and coercivity of the samples were reduced, and the coercivity of all samples was lower.