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题名 Mn-Zn铁氧体薄膜制备与性能研究
姓名 王兰喜
院系 物理科学与技术学院
专业 凝聚态物理
学位名称 理学硕士
外文题名 Preparation and Studies of properties of Mn-Zn ferrite thin films
第一导师姓名 魏福林
关键词 锰锌铁氧体;薄膜
外文关键词 Mn-Zn ferrite;thin films
学科 理学
摘要 软磁铁氧体是铁氧体发展史的主干。目前软磁铁氧体已经广泛地应用于电信、仪器仪表、自动控制和计算机技术等方面,成为品种最多、应用最广的一类磁性材料。而未来的电子元器件进一步朝着小型化、集成化方向发展,部分器件将由三维的体材料向二维的薄膜材料方向发展:微波及毫米波器件;磁化效应器件;高密度、大容量的薄膜磁记录介质;薄膜型磁头,磁传感器;薄膜变压器以及薄膜电感器等。目前薄膜电感器的磁介质层大部分采用金属或金属合金材料,这些材料具有高的电导率,从而在高频使用时会产生严重的涡流损耗和趋肤效应,成为这些材料高频应用的主要瓶颈,使其应用频率范围受到限制。从而,具有高电阻率的铁氧体薄膜以其优异的高频电磁特性,良好的机械耐磨性和稳定的化学性能而成为颇具应用价值的材料引起人们的关注。 因为MnZn铁氧体薄膜具有电阻率高、高频特性及软磁性能好等原因在薄膜电感介质中具有很大发展潜力。但是MnZn铁氧体对制备条件过程中的诸多因素敏感,比如锰的变价、氧的流失,锌离子挥发等,如果条件控制不当,将会造成薄膜性能的恶化。 本文对制备薄膜条件的控制进行了研究,并对薄膜的性能进行了探讨。本论文制备的MnZn铁氧体样品具有低的Hc,原因可以在以下方面给出解释:(1)本实验中薄膜中的晶粒尺寸小于20nm,晶粒之间存在交换耦合作用,使矫顽力降低。(2)基片和薄膜的晶格常数以及热膨胀系数是否匹配,如果匹配较好,将会降低界面处的应力,使矫顽力降低。(3)薄膜比较致密,缺陷少;但是薄膜的Ms也较低,这是我们不希望的,但是铁氧体薄膜的Ms一般会比块体的要低,这在其他人的工作中也普遍存在,主要原因可能是(1)纳米晶薄膜的晶粒表面存在自旋钉扎引起的磁性死层。(2)另外从本实验的XRD中可以看到有部分的非晶态生成,也有可能造成Ms的降低。(3)Mn2+被氧化成Mn3+, Mn3+倾向于占据B位,又Mn3+的磁矩小于Mn2+,所以使总磁矩减小。最后我们通过穆斯堡尔谱在微观方面对Mn0.5Zn0.5Fe2O4,Mn0.1Zn0.9Fe2O4成分的样品进行了讨论,得到了(1)Zn2+倾向于占据A位,将Fe3+挤到B位上,当A位的离子过分减小时,会导致总磁矩减小,平均超精细场减小。(2)给出薄膜中的磁矩方向并不是严格平行于 膜面,而是有一个夹角,在20o~30o 。
外文摘要 Soft magnetic ferrite is the strongest branch of the ferrite development.At present,soft magnetic ferrite has been used in many areas such as telecommunication, instruments and meters,self-control,computer technology and so on.Soft magnetic ferrite has become a kind of magnetic materials which are the most abundant and common. To be smaller and more integrated is the direction of electronic components'' development in future,so bulk materials will not satify the requirements. Magnetic thin films with high resistivity were advanced for applications to micro-inductors and micro-transformers. Metal alloys have high conductivity and serious eddy currency loss for high frequencies so that their applications are limited.Thus,soft magnetic ferrite thin film with high resistivity is a valuable media for film inductor. MnZn ferrite film has the good character of high resistivity,good quality at high frequency and good performance of soft magnetism.But, in the preparation there are many factors that are not easy to control,MnZn ferrite is sensible to its environment.In this paper,I have got the best conditions in preparation. To analyse the results of the samples,low Hc and Ms have been observed.Generally speaking,the Hc of thin film is higher than that of bulk,but in this paper the lowest Hc of Mn0.5Zn0.5Fe2O4 thin film on MgO(100) decreases to 27 Oe which is a better value of rf sputtering preparation.Low Hc also is observed on Si and other substrates.From the SEM,the crystal grain size is smaller than 20nm.Exchange coupled interaction is used to explain the results.Furthermore,some other possible reasons which are stress,defect and so on are discussed.The low Ms is not expected,but the results in this paper may be caused by some reasons:(1),through the XRD,I conclude there may be some amorphous states in the films.(2),there may be dead layers on the surface of crystal grains.(3),Mn2+ was oxidized to Mn3+ and Mn3+ has a relatively higher crystal field stabilization energy for octahedral coordination.Thus it tends to stay at the octahedral B site.The magnetic moment of Mn3+ is smaller than Mn2+.So it leads to decrease the total magnetic momen and thus the Ms.From the data of the Mossbauer spectra,we can conclude some information:(1) The data certificates that Zn2+ tends to occupy the A site,with the increase of the content of Zn2+,it will lead to decrease the total magnetic moment and the hyperfine field Hhf .(2) The magnetic moment is not parallel to the film ...
研究领域 磁学与磁性材料
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