Nano-Mn-Zn ferrite powders prepared by boiling reflux and Properties

Title: Nano-Mn-Zn ferrite powders prepared by boiling reflux and Properties
　　Author: Dai Hui Cui
　　Degree-granting units: South China University of Technology
　　Keywords: Mn-Zn ferrite;; boiling reflux method;; nano-powder;; rare-earth doped;; magnetic
　　Summary:
　　Magnetic nano-magnetic materials is the study of today's hot, soft magnetic materials in most varieties, the largest amount, is the most widely used soft magnetic ferrite materials. Nano-Mn-Zn ferrite material as an important soft magnetic material has broad application prospects. In this paper, nanocrystalline soft magnetic Mn-Zn ferrite powder preparation methods Neodymium Magnets and properties were studied.
　　In this paper, boiling reflux, for δ-FeOOH as a precursor, direct synthesis of MnZn ferrite spinel structure of nano-powders. Studied the precipitation pH, reaction time, the impact of process factors on the product come to the right of co-precipitation process prepared by boiling reflux; using XRD, TEM, VSM and other testing methods to characterize the product, return phase of the conversion reaction dynamics, thermodynamics, reaction mechanisms, such as magnetic properties were analyzed. Studies have shown that by adjusting the pH value and the return time can be from less than greater than 10nm to 20nm Mn-Zn ferrite powders with different particle sizes to obtain the best return full time to the product of 6h. pH of the reaction intensity and the magnetic properties have a significant impact, co-precipitation obtained when the pH value of about 13.0 Preparation of Nanoparticles powder size of about 20nm, the saturation magnetization of 46A.m2/kg.
　　In order to suppress Nanoparticles reunion, physical dispersion and chemical dispersion will combine the use of physical means to reunite the solution, then add the dispersant stabilization of the particle, can achieve good dispersion, good dispersion obtained with Mn-Zn ferrite nanopowders.
　　This paper also studied the rare http://www.everbeenmagnet.com/en/products/110-sintered-neodymium-magnets earth elements (La, Nd, Gd) replace the spinel ferrite structure and magnetic properties. When the rare earth ions replace the Fe3 spinel ferrite lattice, the rare-earth ions into the spinel lattice may also be the formation of compounds into the grain boundary. The study found that rare earth ions (La3, Nd3, Gd3) and effective magnetic moment and the difference in ionic radius of rare earth ion doped spinel ferrite will reduce grain size and lattice constant, and its coercive force Hc is increased, the saturation magnetization changes and add the amount of the rare earth ions.
　　Degree Year: 2010