高频电感用Z型平面六角铁氧体材料研究

【作者】 罗俊；

【导师】 贾利军；

【作者基本信息】 电子科技大学 ， 电子信息材料与元器件， 2009， 硕士

【摘要】 随着通讯技术向高频化方向的发展以及高速数字电路的快速发展,超高频段上的电磁干扰（EMI）问题日益突出,迫切需要能工作在超高频段且性能优异的软磁铁氧体介质材料。其中Z型六角铁氧体由于具有较高的磁晶各向异性,成为最有可能替代尖晶石铁氧体在超高频段应用的磁性介质,有望用作高频片式电感用铁氧体材料和超高频段抗电磁干扰对策元件用微波铁氧体材料。本文正是针对上述问题,以Z型六角铁氧体材料为研究对象,在深入分析了合成机理、掺杂改性和低温烧结机制的基础上,对材料和工艺做了探索性和创新性的研究,主要内容为:一、研究了工艺条件对Z型六角铁氧体材料电磁性能的影响机理。按照工艺流程改变预烧温度、升温速率、烧结温度和保温时间等工艺参数,通过扫描电镜分析、X-射线衍射分析等手段剖析了改变工艺参数对六角铁氧体材料微观结构的影响规律,通过对材料复数磁导率、介电常数以及品质因数等的测量掌握了工艺参数对材料电磁性能的影响规律。二、研究了不同离子取代以及掺杂剂对Z型平面六角铁氧体的改性机制。分别研究了Sr²⁺、Ti4+-Zn²⁺离子取代以及MnCO3、P2O5和Y₂O₃掺杂对Z型平面六角铁氧体显微结构和电磁性能的影响。发现Sr²⁺离子与Ti4+-Zn²⁺离子取代能够有效的提高Z型平面六角铁氧体的磁导率。发现Y₂O₃掺杂析出的Y3Fe5O12石榴石相改善了六角铁氧体的介电常数和磁导率的频率特性。揭示了P2O5掺杂促进晶粒生长从而获得高磁导率的影响机理。发现MnCO3掺杂在改善材料介电特性的同时还促进了磁导率的增加。三、研究了Bi₂O₃、Bi₂O₃-SiO2和Bi₂O₃-MgO掺杂对低温烧结Z型六角铁氧体的作用机理,同时研究了氧气氛低温烧结对Z型六角铁氧体的影响,发现Bi₂O₃-SiO2和Bi₂O₃-MgO掺杂以及氧气氛低温烧结显著改善了Z型六角铁氧体材料的高频电磁特性。四、采用sol-gel法合成超细的六角铁氧体粉料（NZHP）并在此基础上制备了低温烧结Z型平面六角铁氧体的材料。同时研究了掺入由溶胶-凝胶法获得的同成分纳米粉体（NZHP）对固相反应法制备低烧Z型平面六角铁氧体的改性机理,利用纳米-微米粒子匹配的方法获得了同时具备高磁导率和较高磁品质因数Q的低温烧结Z型平面六角铁氧体材料。更多还原

【Abstract】 With the development of communications technology to high-frequency and the rapid development of high-speed digital circuits, the electromagnetic interference （EMI） is becoming an increasingly serious problem and the excellent soft magnetic materials able to work in the high frequency band are required urgently. Especially, Z-type hexaferrties are among the most widely used soft magnetic materials, instead of spinel ferrite for high-frequency application due to their high magnetic anisotropy. It can be used to the chip inductors for high-frequency and anti-EMI countermeasure devices for ultra-high frequency.In this thesis, the synthesis mechanism and the basic mechanisms of modification and low-temperature sintering of Z-type hexagonal ferrite have been analyzed. Then a series of novel materials and its preparation are explored and investigated.The main results are as follows:1. The effects of preparation process on the microstructures and electromagnetic properties of hexaferrites and the relative mechanisms were studied in detail. The presintering temperature, firing rate, sintering temperature, and holding time were changed regularly to investigate the phase formation and the microstructure evolvement of hexaferrites by means of X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The variation of complex permeability, dielectric constant and quality factor with preparation parameters was studied.2. The modification mechanisms of different dopants were investigated. The variation of microstructures and electromagnetic properties of hexaferrites with different Sr²⁺, Ti4+-Zn²⁺, MnCO3, P2O5 and Y₂O₃ contents were investigated. The Sr²⁺ and Ti4+-Zn²⁺ addition can effectively increase the permeability. The Y3Fe5O12 phase was found in all samples with Y₂O₃, resulting in the improvement of electromagnetic properties of hexaferrites. The influence of the increasing grain size of the samples with P2O5 on the high permeability was discussed. The additive MnCO3 improved the complex permeability and the complex permittivity.3. The mechanisms of low-temperature sintering of the hexaferrites with Bi₂O₃, Bi₂O₃-SiO2 and Bi₂O₃-MgO were investigated. The influence of Bi₂O₃ additive on the phase composition, microstructures and electromagnetic properties of hexaferrties was revealed. The significant improvement of high-frequency characteristics was obtained for the samples with Bi₂O₃-SiO2 and Bi₂O₃-MgO additive. The high-frequency electromagnetic properties of Co2Z ferrite was also improved by sintered in oxygen atmosphere.4. Z-type hexaferrites prepared by sol-gel method were investigated. A novel route has been developed to prepare low-temperature sintered Z-type hexaferrites. The nanoparticles derived an improved sol-gel method were utilized to synthesize the low-temperature fired Z-type hexaferrite by a solid-state reaction method. The Z-type magnetic material with higher initial permeability and higher quality factor were obtained for the sample with NZHP.更多还原