共查询到19条相似文献,搜索用时 62 毫秒
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用聚乙烯醇(PVA)溶胶-凝胶法制备了Co0.5Ni0.5Fe2O4铁氧体纳米颗粒,并对其进行了粉末X射线衍射(XRD)分析和高温穆斯堡尔测量。Co0.5Ni0.5Fe2O4铁氧体纳米颗粒样品的晶格常数比块体样品的大,这可能是由于纳米样品中表面离子的比例增大而引起的晶格膨胀所致。高温穆斯堡尔谱表明,四面体位(A位)和八面体位(B位)的德拜温度分别为θA=181±24K,θB=137±10K。在500K附近,开始产生明显的离子迁移,Fe3 离子从A位迁往B位。 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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用化学沉积法制备了Ni100-xBx(x=1.95,2.13,2.40,3.90,6.70)纳米磁性薄膜系列样品。X射线衍射(XRD)分析表明,所有样品的晶粒尺寸均在6~12nm之间。利用振动样品磁强计测量了样品的磁学参数。发现该系列样品的晶格常数、晶粒尺寸、饱和磁化强度均随B含量的增大而减小,并且均在x=2.40附近出现转折点,表现出相同的变化趋势。 相似文献
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采用射频溅射法在Si(001)基片上制备了CoFe_2O_4 (CFO)薄膜,分别采用原子力显微镜(AFM)、X射线衍射仪(XRD)、振动样品磁强计(VSM)进行测试和分析.结果表明,随着退火温度的升高,晶粒逐渐增大,在600℃左右退火,晶粒长大受到抑制;M_s和H_c随退火温度的升高都是先增大后减小;薄膜晶粒大小和膜内晶格应力导致垂直膜面方向矫顽力大于平面方向矫顽力.在600℃退火,H_(c⊥)/H_(c∥)值达到了2.72,表明制备的CFO薄膜具有高度垂直各向异性. 相似文献
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Ga-doped ZnO (GZO) nanoparticles were synthesized by co-precipitation process from starting precursors zinc dichloride (ZnCl2) and Gallium (III) nitrate hydrate (GaN3O9). The deionized (DI) water was selected as the solvent. The as-precipitated powders were calcined at different temperature of 700 and 1000 °C for 2 h. For all samples, their crystal structures were investigated by X-ray diffraction (XRD) and surface morphologies were observed by a field emission scanning electron microscope (FE-SEM). The XRD results revealed that, the crystallinity of powders increases when the calcination temperature increases. Moreover, it is noticed that the intermixture phases of ZnO and Ga2O3 occur when the Ga doping content is exceeded the solubility limit of about 10%. In addition, SEM micrographs show the decrease of particle size with increasing Ga doping content due to lattice distortion that can hinder the crystal growth of ZnO. 相似文献