【作者】 范军；

【导师】 冯则坤；

【作者基本信息】 华中科技大学 ， 微电子学与固体电子学， 2006， 硕士

【摘要】 本文主要介绍了多层片式电感用低温烧结六角晶系铁氧体的晶体结构、制备工艺及电磁特性。一般情况下单相的铁氧体具有很高的烧结温度,从而不能与Ag电极共烧来制做多层片式电感,因此如何在不明显降低六角晶系铁氧体材料电磁性能的前提下如何降低其烧结温度也就是本文主要的研究内容。使用在超高频范围内的多层片式电感不能使用传统的低温烧结尖晶石铁氧体材料,由于特殊的晶体结构六角晶系铁氧体具有相对尖晶石铁氧体较高的Snoek积和自然共振频率,这些特点使其适于作为高频多层片式电感的磁性介质材料。为降低其烧结温度需采用两个步骤来实现:其一就是配方中加Cu,其二就是掺杂少量Bi₂O₃。因为Y型六角晶系铁氧体具有相对较高的自然共振频率,本文选作Co₂Y为主要的研究材料。用Cu离子置换Co₂Y中的部分Co离子成为Co_2-XCu_XY型六角晶系铁氧体,再掺杂少量的Bi₂O₃能够有效降低其烧结温度。改变Cu离子的置换量X和Bi₂O₃的掺杂量得到25种不同的实验样品,这些样品都是用传统的固相反应法来制备,对制备好的样品进行电磁参数的测试和分析可以选出具有较低的烧结温度和最优的Cu离子置换量X及Bi₂O₃的掺杂量的样品,实验证明在Cu离子置换量X=1.0及掺杂5.0wt%的Bi₂O₃的情况下样品的烧结温度低至930℃,但总体来说这些样品的磁导率都不超过4.0。用Zn离子来置换部分Co离子和Cu离子可以提高材料的磁导率至11.3,这是用来调节材料磁导率的可行办法。更多还原

【Abstract】 The crystal-structure, fabricating process and electronic-magnetic properties of the low-temperature-sintered hexagonal ferrites applied in Multilayer Chip Inductor（MLCI） are introduced in this paper. Usually the sintering temperature of the single phase of hexagonal ferrites is very high. So the main task of the paper is to lower the sintering temperature of hexagonal ferrites without largely degenerating the electronic magnetic properties.The spinel ferrites cannot be used as the inner magnetic dielectric in the MLCIs working in Ultra High Frequency（UHF） range. Due to special crystal-stucture the hexagonal ferrites has higher Snoek products and resonance frequency than the spinel ferrites. These advantages make it adapt to used as the inner magnetic dielectric in high frequency MLCIs. In order to decrease the sintered temperature of hexagonal ferrites two steps must be introduced: the first one is to add Cu in the formula, the last one is to mix it with some Bi₂O₃.The Co_2-XCu_XY type hexagonal ferrites was chosen to research because of its relative high nature resonance frequency. It is an effective way to decrease the sintering temperature that replacing the Co ion with Cu ion and mingle with some Bi₂O₃ in the Co₂Y type hexagonal ferrites. Twenty-five samples were prepared by changing the content of the Cu ion and the Bi₂O₃. All these samples were manufactured by the traditional solid-state reaction method. The sample which has a lower sintering temperature and optimal contents of the Cu ion and the Bi₂O₃ can be selected by analyzing the measured electronic-magnetic properties of all the samples. It is testified that the sintering temperature of the sample was decreased to 930℃by the Cu ion content X=1.0 and 5.0 wt% Bi₂O₃. In general all the relative permeabilities of these samples don’t exceed 4.0. The relative permeability can reach at 11.3 by replacing some Co ion and Cu ion with Zn ion in the materials. It is a practicable method to tailor the permeability of hexagonal ferrites.更多还原