The Magnetic Property's Reseach Of Co, Sm Doping NiCuZn Ferrite By Sol-gel Synthesis

Ferrite is a soft magnetic material, It is widely used in the computer and the field of information. such as, the magnetic tablets of the computer which are used to store information, telephone transformers, inductors, magnetic heads for recording, magnetic amplifier and the antenna of the radio. The NiCuZn ferrite is one of the ferrite, the structure of it is spinel and grain size closes to the scale of nanometer, the preparing temperature is low, the Curie temperature is high. hysteresis loop is small, so it is a kind of soft magnetic material. The changes of hysteresis loop from a material lead to the movement of domain walls. There are many ways to preparing the spinel ferrite. Such as, ball milling, precipitation, hydrothermal method, chemical vapor and sol-gel method. Preparing way is very important, which requires sintering temperature is below 1000℃, as reported in the literature.On one hand, the sol-gel method is easy to control the reaction temperature and effectively prevent the oxidation during milling. On the other hand, it can low the sintering temperature. If NiCuZn ferrite was doped, their lattice parameters, grain size of the unit cell volume and magnetic properties of ferrite can be improved effectivelyIn this thesis, we study the doping A and B site of the NiCuZn ferrite.1. Sol-gel synthesis of Ni0.24Cu0.2Zn0.56-xCoxFe2O4(x=0.1,0.2,0.3,0.4) is A site doped, divalent cobalt ions replace divalent zinc ions of A sites。According to the XRD spectra of the (311), (220) (511), (440), (222), (400) and (422) peak, the diffraction peaks show that the structure of the samples is only spinel ferrite. The character of temperature and magnetic susceptibility indicates that the compound is ferromagnetic. The paramagnetic Curie temperature of A1(x=0.1),A2(x=0.2) sample are 580K and 670K, this temperature can be measured by studying the magnetic exchange interaction in the character of temperature and reciprocal magnetic susceptibility. Hysteresis loop shows coercivity (Hc) and remanent magnetization (Mr) increases with the change of doping. This may be that the magnetic anisotropy constant changing with the particle size and domain wall movement caused.2. Sol-gel synthesis of Ni0.24Cu0.2Zn0.56SmxFe2-xO4(x=0.1,0.2,0.3,0.4) is B site doped. Trivalent Sm replace trivalent Fe of B sites.According to the XRD spectra of the (311), (220) (511), (440), (222), (400) and (422) peak, the diffraction peaks show that the structure of the samples is only spinel ferrite. The character of temperature and magnetic susceptibility indicates that the compound is ferromagnetic1. The paramagnetic Curie temperature of B1(x=0.1), B2(x=0.2) sample are 490K and 630K, this temperature can be measured by studying the magnetic exchange interaction in the character of temperature and magnetic susceptibility. Hysteresis loop shows coercivity (Hc) and remanent magnetization (Mr) increases with the change of doping. This may be that the magnetic anisotropy constant changing with the particle size and domain wall movement caused.At last, I give the simply summary of this thesis and the prospect of the doped NiCuZn ferrite magnetic property in their field.