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采用射频(RF)磁控溅射法在蓝宝石基片上制备M型钡铁氧体(Ba M)薄膜,研究了薄膜厚度对Ba M铁氧体薄膜的结构及磁性能影响。结果显示,样品的衍射峰全部为Ba M薄膜的(00l)衍射峰,表明样品都具有良好的c轴取向性。显微结构分析结果表明,在膜厚为40~90nm范围内,薄膜样品表面主要为c轴取向的片状晶粒,未出现c轴随机取向的针状晶粒;当样品厚度增加至140nm时,出现了较明显的针状晶粒;随着薄膜厚度进一步增加到190nm时,样品表面出现了大量c轴随机取向的针状晶粒,且部分针状晶粒长度达到了μm级。磁性能测试结果显示,随着薄膜厚度的增加,薄膜样品饱和磁化强度降低,垂直膜面方向矫顽力和剩磁比减小,膜厚40~90nm范围的薄膜在垂直膜面方向获得了最大剩磁比和矫顽力,表现出较好的磁晶各向异性。 相似文献
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利用溶胶-凝胶自蔓延燃烧法制备了钡铁氧体纳米粉体,同时利用X射线衍射(XRD)、场发射扫描电子显微镜(FSEM)研究了钡铁氧体的微结构及形貌.结果显示制备的样品为单相磁铅石型结构钡铁氧体,晶粒尺寸在50nm左右.另外,利用振动样品磁强计(VSM)研究了样品的室温及高温磁性能,结果表明钡铁氧体在室温时具有较高的矫顽力(μ0Hc=0.557T)和饱和磁化强度(Ms=64.34Am2/kg),纳米钡铁氧体的磁性能随温度的升高而降低,其居里温度约730K.最后,探讨了纳米钡铁氧体颗粒间的相互作用,纳米钡铁氧体颗粒间不存在交换耦合作用,而是以长程静磁相互作用为主,这对于提高垂直磁记录材料的信噪比是非常有益的. 相似文献
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前言世界上第一台电机就是永磁电机,所以利用永磁体所产生的磁场来制造电机有很悠久的历史,由于当时永磁材料的磁性能低,制成的电机非常笨重,即被电励磁电机所取代。本世纪四十年代以后,具有较高剩磁的铝镍钴和具有较高矫顽力的铁氧体永磁材料相继先后出现,永磁电机又获得生机,在微特电机领域里占有重要位置,但铝镍钴永磁易去磁、矫顽力较低;铁氧体永磁的剩磁较低,使 相似文献
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通过将掺Co和Ti的超细钡铁氧体粒子(氵弥)散并粘附到SiO_2颗粒上来测量其矫顽力的方法,研究了这种无聚集现象的超细粒子的内禀矫顽力及聚集作用的影响。对于径厚比值小的钡铁氧体小片状粒子而言,其矫顽力随样品中铁氧体浓度下降而上升,最终获得了一个恒定值,这个值可以看作是粒子的内禀矫顽力。对径厚比值小的片状钡铁氧体粒子而言,其矫顽力随着粒子聚集而下降,而径厚比大的粒子情况相反。径厚比适中的粒子,其矫顽力不随聚集现象变化。矫顽力随聚集现象升高的行为似乎是钡铁氧体小片粒子的固有特性,它是由粒子堆排聚集而引起的,粒子堆排聚集之后,其行为类似于径厚比值小的粒子。 相似文献
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钡铁氧体原始配方中添加MnCO_3,在一定范围内随MnCO,含量的增加,坝铁氧体的剩磁B_r升高;矫顽力H_c有所下降。适量的MnCO_3可制成具有B_r=3850Gs;H_c=2450Oe;最大磁能积(BH)_(max)=3.27MGsOe的钡铁氧体,其性能可达日本同类产品的水平。同时添加MnCO_3还可以适当地降低预烧温度。 相似文献
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用溶胶-凝胶自蔓延燃烧法在700℃退火制备了六角晶系BaFe12O19铁氧体纳米材料,并采用原位合成的方法在其表面修饰了一定量的导电聚苯胺(PANI).借助FTIR、XRD、TEM和VSM等分析手段表征了样品的形貌、结构及磁性能.结果表明,当修饰质量比为10%、30%时,饱和磁化强度(Ms)从未修饰的36.4 Am2/kg分别下降至31.3 Am2/kg和18 Am2/kg, 而矫顽力(Hc)由未修饰的44 kA/m分别增大至55.7 kA/m和62.8 kA/m.同时,剩磁比(Mr/Ms) 均在0.6左右.另外,对聚苯胺修饰前后钡铁氧体磁性能的变化以及与磁性能有关的纳米尺寸效应进行了分析讨论. 相似文献
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H. Basantakumar Sharma 《Integrated ferroelectrics》2018,193(1):14-23
AbstractFerroelectric barium titanate and multiferroelectric bismuth ferrite thin films have been fabricated by using sol-gel processing technique. The starting materials for fabrication of were barium 2-ethyl hexanoate and titanium (IV) isoproposxide. Bismuth nitrate and ferric nitrate were the precursors for the fabrication of thin films. The as-deposited films were annealed at higher temperature for crystallization. The X-ray diffraction study on the films showed that the as-grown films were found to be amorphous that crystalized to proper phases by annealing at 550?°C in air for one hour. All the samples showed high optical transparencies in the visible frequency range. The room temperature dielectric constant and loss tangent of barium titanate thin films at 1?kHz frequency were found to be 400 and 0.01 respectively. Both the dielectric constant and loss tangent showed small dispersion in the frequency range of 0.10–1000?kHz range. The ferroelectricity in barium titanate thin films was confirmed by the presence of bell shaped capacitance-voltage (C-V) butterfly loop and saturated polarization-field (P-E) hysteresis loop. The as-grown bismuth ferrite thin films were also found to be amorphous that crystallizes after annealing at 500?°C. These films also showed high optical transparencies in the visible region. The bismuth ferrite thin film samples showed saturated hysteresis loop and magnetic polarization-magnetic field hysteresis loop as well, confirming the multiferroic nature of the samples. 相似文献
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A modified sol–gel method has been developed to prepare for the barium strontium titanate (Ba0.6Sr0.4TiO3, BST) thick films. The films were deposited on either Pd–Ag electroded alumina substrates (Pd–Ag/Al2O3) or silver electroded alumina (Ag/Al2O3) substrates by spin coating technique or screen printing technique. The thickness of the film was in the range of 2–10 μm. The key point of the process is to disperse fine-grained BST ceramic powders prepared by high energy ball mill into BST sol solution to form a slurry for spin coating and screen printing. In order to enhance the stability of the slurry and to avoid crack formation of the thick film, organic macromolecular poly-vinylpyrrolidone (PVP) was added to the sol solution. The structure and surface morphology of the films were studied by X-ray diffraction and Scanning Electron Microscope (SEM) techniques. It is revealed that the thick films exhibit pure perovskite phase and are crack-free, dense and homogeneous. The dielectric constant and loss tangent of the thick films are about 1200 and 0.01, at 10 °C and 1 KHz, respectively. 相似文献
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采用有机金属裂解法在Pt/TiO2/SiO2/Si基板上制备M型钡铁氧体(Ba M)薄膜,并着重研究了螯合剂乙二胺四乙酸(EDTA)含量对Ba M薄膜结构、磁性和微波性能的影响。研究发现,当EDTA∶(Ba2++Fe3+)=1(摩尔比)时,Ba M薄膜形成较多的六角形状晶粒,而且磁性能和微波性能较佳,沿c轴生长的取向度高达0.91,饱和磁化强度Ms为302k A/m(μ0Ms=0.38T),在50GHz时铁磁共振线宽ΔH为22k A/m(277Oe)。这是因为适量的EDTA不仅在溶液挥发时能够阻止金属离子的分离和间歇性的沉淀,并且能够促进成形成均匀的前驱液,从而在前驱液分解时能促进形成Ba M,在经过热处理后易形成沿c轴取向、具有六角形状晶粒的Ba M薄膜。 相似文献
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在钡铁氧体原始粉末中加入不同的分散剂进行球磨制备钡铁氧体浆料.通过粒度分析、扫描电镜观察、红外光谱分析、X射线衍射分析及粘度测量研究了分散剂类型(十二烷基硫酸钠、聚乙二醇和它们的复合物)、pH值等因素对钡铁氧体分散行为的影响.结果表明,用分散剂对钡铁氧体进行改性后,能够提高其分散性,且采用复配分散剂比单一分散剂能够获得更好的分散效果.改性后钡铁氧体的红外光谱分析表明,分散剂可以降低钡铁氧体粒子的表面活性.改性后粉末的XRD分析表明,使用复配分散剂、pH=10球磨16h后没有改变钡铁氧体的相结构. 相似文献
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NiZn铁氧体靶材及薄膜的磁性能和微观结构 总被引:3,自引:1,他引:2
首先采用固相反应法制备NixZn1-xFe2O4铁氧体靶材(x=0.2~0.8),研究了Ni取代量对靶材性能的影响;并选用Ni0.5Zn0.5Fe2O4靶材,采用射频磁控溅射法在Si(100)基片上制备了NiZn铁氧体薄膜.靶材样品的分析结果表明,随Ni含量增加,样品的X射线衍射峰向高角方向移动,晶格常数和平均晶粒尺寸都单调减小;当x=0.5~0.6时,NixZn1-xFe2O4铁氧体饱和磁感应强度Bs较高,矫顽力Hc较小.薄膜样品的分析结果表明,制备的薄膜经800℃退火后,呈尖晶石结构,并沿(400)方向择尤取向;薄膜的饱和磁化强度Ms和面内矫顽力Hc分别为310kA/m和8.833kA/m. 相似文献