【作者】 陈健；

【导师】 冯则坤；

【作者基本信息】 华中科技大学 ， 材料物理与化学， 2007， 硕士

【摘要】 随着现代科学技术的飞速发展,电磁辐射对人类的身心健康及各种电子电气设备产生了不可忽视的危害且日趋严重。因此,研制性能优良的抗EMI材料具有十分重要的意义。Co2Z型六角晶系铁氧体材料由于存在大的各向异性场,可以工作的在GHz频段。国际上主要在离子替代,配方设计,制备工艺等方面对六角晶系体氧体材料开展研究。本文采用稀土离子取代和SiO2掺杂来改善Co2Z型六角晶系铁氧体材料的特性。本文介绍了研究的目的和意义,以及目前所用尖晶石系铁氧体的局限,引出了Z型六角晶系铁氧体材料的巨大潜力。展示了目前国内外Co2Z型六角铁氧体的主要研究方法和研究成果。研究了六角晶系铁氧体的基本理论。系统研究了六方晶系Z型铁氧体的合成条件,结构与电磁性能。首先采用普通陶瓷工艺制备未掺杂时的Z型六角晶系铁氧体Ba3Co2Fe24O41,研究其制备工艺及电磁特性,烧结温度为1200℃。接着采用稀土元素R=La、Gd、Ho取代,制备Ba3Co2RxFe24-xO41,取代量X=0～0.3,烧结温度为1200℃。发现除La取代外,样品的性能较未稀土离子取代时有较大的改善,尤其当Gd取代量X=0.1时,样品的具有以下特点:①高磁导率;②高损耗;③高自然共振频率。为了进一步提高性能,可以通过改善材料的微观结构来提高磁导率。最后在保持稀土Gd取代时,添加不同质量分数的SiO2,烧结温度仍为1200℃。发现当SiO2的掺杂量为0.2wt%时,磁导率的实部与虚部都得到了提高,自然共振频率向高频移动。而掺杂SiO2对复介电常数的影响不是很明显。更多还原

【Abstract】 With the rapid development of modern science and technology, electromagnetic radiation on human health and all kinds of electrical and electronic equipment has the increasingly serious harm.Therefore, the development of material with good performance against EMI is of great significance.Co2Z-type hexagonal ferrite materials because of the large anisotropy field,can be used in the GHz.In the international ion substitution, formulation, preparation technology are the main research on the hexagonal ferrite materials.In this paper, I used the replacement of rare earth ions and doped SiO2 to improve the properties of Co2Z-type hexagonal ferrite material.This paper presents a study of purpose and meaning, and the limitations of currently used spinel ferrite, leds to Z-hexagonal ferrite materials which have enormous potential and displays the main research methods and research results of Co2Z– hexaferrites at home and abroad.Study the basic theory of the hexagonal ferrite and the conditions for the synthesis, structure and electromagnetic properties.First, without doping the polycrystalline Ba3Co2Fe24O41 were prepared by an usual ceramic sintering method.Study the preparation and its electromagnetic characteristics, the sintering temperature was 1200℃.Then with the replacement of REE,R = La, Gd, Ho the Ba3Co2RxFe24-xO41 was prepared, substitution X=0~0.3, and the sintering temperature was1200℃.Found that apart from La replaced, the properties of the samples were a larger improvement than without the replacement rare-earth ions.Particularly when the Gd substitution X=0.1, the samples with the following features :①high permeability;②high attrition;③high natural resonant frequency.To further enhance performance, we can improve the microstructure of materials to improve the permeability rate.Finally with the Gd replacement, different content of SiO2 were dopped.Sintering temperature was still 1200℃.When the SiO2 content of the doping was 0.2wt%, the real and imaginary parts of the permeability have been improved, the natural resonant frequency shifted to high frequency.Doped SiO2 there is not obvious impact on complex permittivity.更多还原