C02Z型高频软磁铁氧体材料的研究进展

综述了近年来高频用软磁铁氧体材料Co2Z的研究进展,着重探讨了低温烧结和掺杂改性,并指出经过掺杂改性后的可低温烧结软磁铁氧体材料Co2Z在制造高频多层片式电感(MLCI)与吉赫兹频段抗电磁干扰元件(EMI)中具有很好的应用前景.     

Ir4+掺杂Co2Z平面六角软磁铁氧体的磁性能

采用普通陶瓷工艺制备了Ir4+掺杂的Co2Z型平面六角铁氧体,研究了少量Ir4+掺杂对Co2Z型铁氧体材料结构和磁性能的影响.结果表明,少量掺杂Ir4+的Co2Z型铁氧体仍具有单相的Z型平面六角结构,其磁导率实部μ′明显提高.随着烧结温度的提高,材料的磁导率实部μ′增大,但截止频率下降.在1275℃烧结的掺杂Ir4+铁氧体样品,其μ′达到16.5,截止频率仍＞1GHz,具有较好的高频性能.     

掺杂Gd的Co_2Z型铁氧体的微结构和高频性能(英文)

采用普通陶瓷工艺制备了Gd掺杂的Co2Z型平面六角铁氧体3(Ba0.5Sr0.5O).2CoO.0.05Gd2O3.10.8Fe2O3,对其微结构和高频性能进行了研究。结果表明,少量掺杂Gd的Co2Z型铁氧体仍具有单相的Z型平面六角结构,其磁导率实部μ′明显提高,可达到13,而截止频率仍大于1GHz,具有较好的高频性能。随着烧结温度的提高,材料的磁导率实部μ′增大,但截止频率下降。少量Gd的掺杂对Co2Z型铁氧体的复介电常数值没有明显影响,但材料的铁电共振峰向高频区移动。     

软磁锰锌铁氧体纳米粉体的烧结特性研究

研究了烧结温度和掺杂对软磁锰锌铁氧体材料性能和微观结构的影响。采用传统成型工艺和冷等静压成型相结合,进行分段烧结,研究坯体的致密化程度和晶粒生长情况。烧结体的密度、微观结构和相组成分别采用阿基米德法、扫描电镜（SEM）和X射线衍射仪（XRD）进行测试分析。烧结体的磁性能用振动样品磁强计（VSM）来测定。结果表明：烧结温度在850℃时材料密度、微观结构和磁性能较好,但还未能达到高性能产品的标准,需要通过掺杂等其他手段进行进一步研究。     

Bi掺杂对Ni-Zn-Cu铁氧体的烧结与磁性能的影响

低温烧结软磁铁氧体是表面组装元件（ＳＭＤ）中的一类关键材料。本文对Ｂｉ掺杂的低温烧结Ｎｉ－Ｚｎ－Ｃｕ铁氧体从烧结性质、结构与相组成、显微形貌、磁结构和磁性质（磁导率、品质因数及频谱）方面进行了研究，在此基础上分析了Ｂｉ掺杂对材料形成过程和磁化机制的影响，发现Ｂｉ对材料磁性能的改进所起的作用主要产生于它对材料显微结构（晶粒、晶界和气孔）的调制。     

Bi-Mo复合掺杂对MgCuZn铁氧体烧结特性和磁性能的影响

为改善MgCuZn铁氧体的低温烧结特性并提高其软磁性能, 采用传统氧化物法制备MgCuZn铁氧体材料, 研究了Bi-Mo复合掺杂对其烧结特性和软磁性能的影响. 结果表明: 复合掺杂Bi₂ O₃和MoO₃适量时(分别为0.6wt％和0.1wt％), 在较低的烧结温度(1020℃)就能获得较高的烧结密度(<4.75g/cm³), 起始磁导率可达1240, 且具有较高的品质因数(100kHz下为33.8). 通过主成分优选、有效的掺杂技术及工艺条件可以提高MgCuZn铁氧体的综合性能, 使其可应用于多层片式电感中.     

BaMn_(0.5)Co_(0.5)Zr_(1.0)Fe_(10)O_(19)软磁陶瓷的微观形貌和磁性研究

用溶胶-凝胶法制备了Mn-Co-Zr离子共掺BaFe12O19的前驱体,经过后期烧结得到BaMn0.5Co0.5Zr1.0Fe10O19陶瓷,研究了烧结温度、预烧温度、球磨时间等对陶瓷微观形貌和磁性的影响。通过XRD、SEM和VSM等对样品进行性能表征,发现相比于纯M型钡铁氧体,掺杂M型钡铁氧体在相同烧结温度和预烧温度情况下,晶粒更细,而且饱和磁化强度更大。当预烧温度为1 000℃,球磨时间8 h,BaM铁氧体陶瓷的致密度、晶粒形貌和磁性能最佳,此时陶瓷饱和磁化强度为59 A·m2/kg,矫顽力5.01 kA/m,密度为4.73 g/cm3,满足在高频领域的应用。可见Mn-Co-Zr离子掺杂对M型钡铁氧体陶瓷的软磁化及其应用有决定性影响,同时掺杂使得产物颗粒粉体晶粒细化,活性增加。     

BST掺杂对Co2Z六角铁氧体相结构及动态电磁参数的影响

采用陶瓷工艺制备Co2Z(Ba3(Co0.4Zn0.6)2Fe23.4O41)六角铁氧体,通过二次球磨掺杂少量BST(BaSrTiO3)铁电材料。研究BST掺杂对Z型铁氧体的烧结温度、相结构、晶粒生长及其在频率1MHz～1GHz的动态相对复介电常数(ε′=ε″r—iε″r)和相对复磁导率(μ=μ′r—iμ″)的影响。结果表明：在BST掺杂量为Co2Z一次预烧料重量比的0～1.5％内．随BST含量增加,形成在Z型六角结构相生长同时,伴生M相六角结构和钙钛矿结构的多相结构;六角结构晶粒明显长大,材料密度增加;μr和εr增大;铁磁共振和铁电共振频率点移向低频。当BST掺杂量为1.5％、频率1MHz时．μ′=28,ε′=100,相对于纯相Co2Z材料μ′r和ε′,明显提高。     

精矿粉和Mn3O4制备MnZn功率铁氧体工艺研究

为了降低功率铁氧体的制备成本,采用传统氧化物陶瓷工艺,用精铁矿粉代替Fe2O3、用Mn3O4代替MnCO3制备出高性能功率软磁MnZn铁氧体.研究了精铁矿粉和Mn3O4制备MnZn铁氧体的固相反应及预烧温度、烧结温度和掺杂对样品磁性能的影响.实验结果表明:精矿粉经氧化生成的α-Fe2O3立即与Mn3O4反应生成MnZn铁氧体,使固相反应更完全;预烧温度为1100℃,烧结温度为1240～1280 ℃时样品性能最佳;适当的掺杂可降低样品的功耗.样品最佳性能如下:μi=2268;Bs=508 mT;Tc=227℃;Po=34.5 W/kg,综合性能达到日本TDK PC30材料性能水平.     

NiO-CoO复合掺杂对高B_s低损耗MnZn铁氧体性能影响

采用传统氧化物工艺制备了NiO-CoO掺杂的MnZn软磁铁氧体材料。研究了NiO、CoO复合掺杂对高Bs低损耗的MnZn铁氧体微结构及电磁性能的影响。结果表明,掺杂0.1%(质量分数)CoO和1.28%(质量分数)NiO的MnZn铁氧体晶粒生长均匀,具有较高的饱和磁感应强度,最低损耗点位于100℃。随着NiO掺杂量的增加,最低功耗点向高温方向移动。CoO掺杂导致材料密度增大,功耗降低。在钟罩炉中按特定烧结曲线烧结MnZn铁氧体具有较好的综合性能:μi=2 198,Pcv=319kW/m3,Bs=540mT(T=25℃),Bs=451mT(T=100℃)。     

低功耗NiCuZn铁氧体的研究

用传统陶瓷工艺制备了Ni0.32Cu0.10Zn0.60O(Fe2O3)0.98铁氧体材料,研究了添加V2O5对材料烧结特性和磁性能的影响。结果表明,当V2O5为0.12%(w)时,晶粒生长均匀、结构较好。此时在50kHz、150mT、100℃测试条件下,功耗有最小值(275.7 kW/m3),其值为未掺杂损耗(689.5 kW/m3)的40%。     

低温烧结Li铁氧体及其频率特性

报道了通过Ｂｉ２Ｏ３的掺杂而获得的较低温度（８８０℃左右）下烧成的Ｌｉ铁氧体的烧结工艺、结构特征及其磁导率的频率特性。发现材料实现低烧的同时也有效地克服了烧结过程中的Ｌｉ挥发，用Ｚｎ和Ｃｏ部分地替代Ｌｉ可有效地提高材料的起始磁导纺和截止频率。     

Effects of the inhomogenous co doping on the magnetoresistance of Zn1-xCo(x)O epitaxial films

A series of Zn1-xCo(x)O epitaxial films around 100 nm with nominal Co concentration from 5% to 15% was prepared by ultra high vacuum (UHV) magnetron reactive sputtering. The optical, magnetic and magneto-transport properties of this series of Zn1-xCo(x)O epitaxial films were investigated, respectively. Resonant Raman spectra indicate the high structural and crystalline quality of these Zn1-xCo(x)O (5 < or = x < or = 15%) films, and confirm a consistent correlation between the substituting Co ions content with the Co doping concentration as well. Paramagnetism, superparamagnetism and ferromagnetism with altered Curie temperature from low temperatures to above room temperatures have been observed in these films by SQUID magnetometry. The broad blocking temperature range indicates the presence of inhomogenous distribution of the magnetic nano-clusters in the superparamagnetic films. However, the magneto-transport behaviors do not strongly respond to the change of the magnetic properties from paramagnetism to ferromagnetism of these Zn1-xCo(x)O films. The lack of efficient coupling between the inhomogenous magnetic nanoclusters and the carrier system in ferromagnetic Zn1-xCo(x)O films highlights the absence of the intrinsic magnetic origins in high structural quality Zn1-xCo(x)O (5 < or = x < or = 15%) epitaxial films. On the other hand, the competition between the spin alignments and the inhomogenous local disorder effect by magnetic ions is suggested to be responsible for the carrier properties and the oberseved magnetoresistance in these Co doping Zn1-xCo(x)O (5 < or = x < or = 15%) epitaxial films.     

EuSr2RuCu2-xZnxO8中Zn对CU的替代效应

通过对EuSr2RuCu2-xZnxO8超导体系的结构、电阻和磁化强度的观测，研究了Zn对Cu的部分替代对其超导电性和磁性的影响。结果表明，Zn部分替代Cu后EuSr2RuCu2-xZnxO8体系仍能保持单相的上限浓度为x=0.2；替代导致样品发生四方－正交的结构相变，并对其超导电性具有强烈的破坏使用，x=0.01的样品在4.2K以上已不再呈现超导电性；替代增强了Ru离子之间的铁磁相互作用，导致铁磁相变温度的提高。     

Microstructure and magnetic properties of Ni–Zn ferrites

Ni–Zn ferrites were prepared in air by using the conventional ceramic powder methodology. The compositions analysed belong to the type NixZn1–xFe2O4 ferrites, with x ranging from 0.3–0.4. Copper wire was coiled round the specimens, previously pressed to a toroidal shape, to characterize their magnetic properties as a function of the frequency of the applied electric field. Powder X-ray diffraction, scanning electron microscopy and microanalysis, and the magnetic susceptibility of the ferrites, were studied, indicating that the highest permeability is achieved at the composition x = 0.3, a result which is correlated to the microstructural characterization. The Curie temperature was also determined to range from 60–130 °C, depending on the specific composition.     

Properties of Dispersion Casting of Y2O3 Particles in Hypo, Hyper and Eutectic Binary Al-Cu Alloys

In the present work,the dispersion casting of Y-2O-3 particles in aluminum-copper alloy was investigated in terms of microstructural changes with respect to Cu contents of 20 （hypo）,33 （eutectic） and 40 （hyper） wt pct by scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS）.For the fabrication of Al-Cu alloy dispersed Y-2O-3 ceramic particles,stir casting method was employed.In case of Al-20 wt pct Cu alloy （hypoeutectic）,SEM images revealed that primary Al was grown up in the beginning.After that,eutectic phase with well dispersed ceramic particles was formed.In case of eutectic composition,Y-2O-3 particles were uniformly dispersed in the matrix.When the Cu is added into Al up to 40 wt pct （hypereutectic）,primary phase was grown up without any Y-2O-3 ceramic particles in the early stage of solidification.Thereafter, eutectic phase was formed with well dispersed ceramic particles.It can be concluded that Y-2O-3 ceramic particles is mostly dispersed in case of eutectic composition in Al-Cu alloy.     

微波多元醇法制备单分散Ni1-xZnxFe2O4/MWCNTs与磁性能

以多壁碳纳米管(MWCNTs)为模板,三乙二醇(TREG)为溶剂,采用微波多元醇法制备MWC-NTs负载组成可控的Ni1-xZnxFe2O4(x=0.4、0.5、0.6)纳米复合材料Ni1-xZnxFe2O4/MWCNTs。其结构和形貌通过XRD、SEM、TEM和EDX进行表征,用VSM测试样品的磁性,并探讨了微波功率、微波时间对镍锌铁氧体负载的影响。结果表明立方系尖晶石结构的单分散Ni1-xZnxFe2O4磁性纳米粒子均匀负载在碳纳米管表面,平均粒径约为6nm;其磁性能与镍锌铁氧体的组成有关,随着Zn含量的增加,饱和磁化强度(Ms)先增大后减小,当x=0.5时Ms达到最大值。矫顽力(Hc)都比较小,在室温下表现为超顺磁性。     

Ferromagnetic Resonance Investigation of Hexaferrite Nanoparticles Prepared by Sol-Gel Auto-Combustion Method

In this study, the magnetic and electromagnetic wave-absorbing properties of barium and strontium ferrite nanopowders prepared by a sol-gel technique were investigated. To study the structural characteristics of hexaferrites, X-ray diffraction analysis was used. Investigation of the morphologies of nanoparticles was carried out by field emission scanning electron microscopy. A vibrating sample magnetometer was used in order to examine the magnetic properties of synthesized hexaferrites at room temperature. Ferromagnetic resonance (FMR) was used to investigate ferromagnetic resonance of the powders. Experimental results indicated that the materials had hexagonal structures with desirable magnetic properties. A low-field absorption signal was observed with the same phase as the FMR absorption in barium hexaferrites.     

Effect of copper oxide on the structure of nano-sized Ni(x)Zn(y)Fe2O4 powders prepared by using self-propagating high temperature synthesis

Nano-sized Cu(x)Ni(x)Zn(1-x-y)Fe2O4 ferrites were prepared by using self-propagating high-temperature synthesis (SHS) and mechanical ball milling. As oxygen pressure increases and copper content decreases in the initial composition, average combustion temperature and combustion velocity increases in the ranges of 947 to 1150 degrees C and 4.2 to 6.5 mm/sec, respectively. The SHS products were agglomerated crystalline powders in which fine particles were present. The average particle of the pulverized SHS product was about 200 nm. Lattice parameters determined by neutron diffractometry are 8.4125 angstroms for Ni0.38Zn0.62Fe2O4 and a = 8.3540 angstroms for Cu0.29Ni0.28Zn0.43Fe2O4.     

参杂尖晶石型镍基铁氧体的磁性能与介电性能

采用溶胶-凝胶法制备了立方晶系尖晶石型镍基铁氧体微粉Ni0.5M0.5Fe2O4（M=Zn、Mn、Cu）,采用X射线衍射仪、扫描电子显微镜、振动样品磁强计和矢量网络分析仪对粉末的结构、形貌、磁性以及电磁性能进行了表征,结果表明,三种粉末在室温下具有超顺磁性,其饱和磁化强度MS分别为76．0、59．4和54．4emu·g-1。在2—11GHz范围内,Ni0.5M0.5Fe2O4的电磁损耗角正切值tgδ随频率的增大而逐渐减小;Ni0.5M0.5Fe2O4和 Ni0.5M0.5Fe2O4的tgδ随频率的增大先增大后减小。