CoFe2O4纳米颗粒的结构、磁性以及离子迁移

聚乙烯醇(PVA)溶胶凝胶法制备出CoFe₂O₄纳米微粉，用X射线衍射研究了铁氧体纳米颗粒的结构.测量了CoFe₂O₄纳米颗粒80—873 K的变温穆斯堡尔谱，发现纳米颗粒的磁转变温度范围为793—813 K，比块体材料的磁性转变温度要低.CoFe₂O₄纳米颗粒的德拜温度θ_A=674 K，θ_B=243 K，比块体材料要小.CoFe₂O₄纳米颗粒超精细场H_f随温度的变化符合T^3/2+T^5/2定理.当温度较高时，平均同质异能移IS随温度的升高而减小，并呈线性关系. 关键词： 纳米颗粒 磁性 穆斯堡尔谱

Structure, magnetic properties and atomic immigration of CoFe2O4 nanoparticles

CoFe₂O₄ nanoparticles have been prepared by sol-gel method. M?ssbauer spectra at temperature varying from 80 to 873 K showed that the atomic site preference of nanoparticles is different from that of the bulk material. The results also showed that the T_c of nanosized CoFe₂O₄ is much lower than that of the bulk counterpart. This decrease of T_c in the nanoparticles may be attributed to the redistribution of Fe and Co cations at the A and B sites. The M?ssbauer spectra also revealed that the hyperfine field varied with the temperature and the hyperfine interaction follows T^3/2+T^5/2 law approximately. The average isomer shift decreases almost linearly with increasing temperature.
Keywords： nanoparticles magnetic properties M?ssbauer spectra