ni-zn铁氧体纳米颗粒结构和磁性能.pdf

,。并利用差热分析(DTA)、扫描电子显微镜(SEM)、X射线衍射仪(XRD)、振动样品磁强计(VSM) 和LCR自动测量仪来分别表征干凝胶的热分解特征以及样品的形貌、晶格结构和磁电性能。DTA表明Znl-xNixFe204铁氧体干凝胶的热分解特征与Ni含氢无关,其热分解温度约为210℃,并且在凝胶燃烧过程中即可合成Znl0N玎e204铁氧体纳米颗粒。Xlm测量结果表明,只需低温热处理即可得到具有单一的尖晶石相的 Zm_xNixFez04纳米颗粒;700。C热处理的样品的颗粒尺寸约为35 I皿;Znl_xNi。Fez04 样品的a随着x增多逐渐减小,并且略大于相应块体材料的口。VSM测量结果表明, Zm_,,NixFe204铁氧体纳米颗粒聪的最大值( emu/g)出现在Ni含量较高的 ,。当 Ni含量较低时纳米颗粒样品的坛小于相应块体的坛,但当Ni含量较高时样品的聪又大于相应块体的腿。,并远远大于块体的风。,样品的坛最大值( emu/g)出现在颗粒尺寸约为100 nln的样品中,此值可以认为是颗粒纳米磁性的临界尺寸(大于100 nm时,颗粒的纳米磁特性逐渐消失)。 ,当颗粒长大到 30nin时,致达到最大, Oe,随后又随颗粒的长大而急剧下降并逐渐接近块体的值。样品的单畴临界尺寸约为30 nnl(小于30眦l颗粒为单畴颗粒)。 SEM测量表明,样品颗粒为球形,大小比较均匀;样品颗粒随热处理温度的升高而增大,900。C以下热处理的样品为单晶颗粒。LCRi911]量表明由纳米颗粒压块烧结的样品的电阻率高达107 MQ·em。关键词: 溶胶凝胶自燃法,Znl_xNi,Fe204铁氧体,纳米颗粒,单畴颗粒,热处理 ABSTRACT TheZnlqN啦?e204 ferritenanoparticles were prepared bysol—gel bustion inorder toinvestigate theirmicrostructure oelectric properties by meas of Differential thermal analysis(DTA),Scanning electronmicroscope(SEM),X-ray diffraction(XRD),Vibrating sample ometer(VSM),and LCR automatic measurement results of DTA indicate that the position characteristic ofdriedgels isindependent ofNi content x,thethermal position temperature isabout 2 00Cand could besynthesized in theself-bustion isobserved from XRD thatZnl-xNixFe204 nanoparticles、Ⅳith pure spinel cubic structure could be abtained only by once heat-treating average grain sizeofsamples heat—treated at700 ℃is about 35 a ofZnl_xNixFe204 nanoparticles declines gradually with increasing x,and islarger thanthatofthebull(.VSM redults show thatdifferentfrom position for thebulk,the maximum Ms()of Znl州订e204 nanoparticles isfound position samples with alower Ni cont