添加剂对钴铁氧体的影响

以废旧锂离子电池为原料,采用水热法制备出纳米晶钴铁氧体,讨论了在制备过程中加入添加剂对钴铁氧体磁性能的影响。借助于XRD对产物的制备过程进行了跟踪检测,并借助于IR、TG、VSM等手段对产物进行了表征。结果表明加入适量冰乙酸有利于钴铁氧体的生成和磁性能的提高,但过量的冰乙酸的加入会使最终产物中含有乙酸根,同时也降低钴铁氧体的磁性能。而在沉淀过程中加入柠檬酸作添加剂则不利于钴铁氧体的生成。     

钴铁氧体纳米粒子制备及其镧掺杂的磁性能研究

为了制备性能良好的钴铁氧体及改善其磁性能,通过改进的溶胶凝胶自蔓延燃烧法成功地制备了钴铁氧体(CoFe2O4)及掺镧(La)钴铁氧体纳米粒子.采用X射线衍射(XRD),透射电镜(TEM)、能谱分析(EDS)、振动样品磁场计(VSM)对所得粒子进行了结构、形貌、成分及磁性能表征.测试结果表明,利用改进的溶胶凝胶法制得钴铁氧体粒度均匀,且成相温度较低,500℃煅烧1h时平均粒径12nm左右;通过掺杂稀土镧元素对所得铁氧体的相结构有较强的影响,所得掺镧钴铁氧体与目标产物一致;所得钴铁氧体具有较高的矫顽力(737.33Oe),并且通过稀土元素镧的掺杂提高了钴铁氧体的矫顽力.     

少量钴掺杂对Mn-Zn铁氧体结构和磁性质的影响(英文)

采用溶胶凝胶自燃烧法制备了钴掺杂的Mn-Zn铁氧体,研究了少量钴掺杂对其结构和磁性质的影响。利用X射线衍射仪对制备的粉末测试发现,Mn0.4Zn0.6-xCoxFe2O4系列铁氧体都具有纯净的尖晶石结构。晶格常数和饱和磁化强度都随着钴替代量的增加而增加。μi-T线具有两个磁导率最大的峰值并且磁导率的第二峰值随着钴的增加向低温移动。磁导率的第二峰值的温度可以通过改变钴含量来调节。基于铁氧体中磁晶各向异性补偿模型,阐明了少量钴掺杂对铁氧体磁性质影响的作用机理。     

钴含量对锰锌铁氧体磁导率温度稳定性的影响(英文)

采用溶胶凝胶自燃烧法制备了Mn0.4Zn0.6-xCoxFe2O4铁氧体,研究了钴掺杂对其结构和磁性质的影响。将自燃烧法制备的粉末进行1,150℃烧结。利用X射线衍射仪对制备的粉末测试发现,Mn0.4Zn0.6-xCoxFe2O4系列铁氧体都具有尖晶石结构。利用VSM对铁氧体进行磁性测试,发现饱和磁化强度与晶格常数的变化规律一致,在钴含量为0.2时,都取得最大值。通过μi-T曲线发现,初始磁导率随着钴含量的增加而降低,居里温度是一个常数。而且,钴含量可以调节磁导率的温度稳定性,在钴含量为0.3时,磁导率具有优良的温度稳定性。基于铁氧体中离子分布的原理,阐明了钴掺杂对铁氧体磁导率温度稳定性的作用机理。     

热处理工艺对尖晶石型Ni0.5Zn0.45Co0.05Fe2O4静磁性能的影响

利用溶胶凝胶法制备了尖晶石型 Ni0.5Zn0.45Co0.05Fe2O4 纳米颗粒,设置了3种热处理工艺,发现随着热处理温度的提高,热处理时间的延长,颗粒长大,静磁性能提高。当热处理温度为800℃,保温8h,材料具有比较好的静磁性能（Ms=30.241Oe,Hc=73.261 emg/g,μi=0.210）。另外,将前驱体在磁场条件下热处理,得到颗粒尺寸比同种热处理工艺未加磁场条件下的大,并且静磁性能有了比较大的提高,其比饱和磁化强度甚至比在更高热处理温度,更长热处理时间下制备的NiZnCo铁氧体大。     

硬模板法合成钴铁氧体微米磁管及磁性纳米粒子

以优质纸纤维和脱脂爆化玉米为硬模板,采用共沉淀法在硬模板表面合成Co2+Fe2+Fe3+-LDHs.然后程序升温在马弗炉中焙烧去除有机成分,得到钴铁氧体微米磁管和纳米钴铁氧体粒子.通过对合成产物进行X射线衍射、扫描电镜、磁强、莫斯堡尔谱等表征表明,合成的管状铁氧体具有和粉末铁氧体相似的磁性和良好的晶体组成;同时发现,所合成的两种形貌钴铁氧体对甲基橙均具有较好的光降解性能.     

以废旧锂离子电池为原料制备CoZnxZrxFe2-xO4磁致伸缩材料

以废旧锂离子电池为原料,采用溶胶-凝胶自蔓延燃烧的方法制备出锌锆离子共取代的钴铁氧体,并对所制备样品的结构、形貌、磁性能和磁致伸缩性能进行探究。结果表明,锌锆离子共取代的钴铁氧体具有尖晶石结构,形貌与纯钴铁氧体比较发生了变化。随着锌锆离子取代量的增加,样品的饱和磁化强度、最大磁致伸缩系数和最大应变导数整体呈现先增加后减小的趋势。在取代量为x=0.050时,样品在较低的磁场强度下取得的饱和磁化强度和最大应变导数分别是87.56 Am~2/kg和-1.81×10~(-9) A~(-1)m,这有利于铁氧体磁致伸缩材料在压力传感器和制动器方面的应用。     

铁氧体化学镀的原理和应用

主要介绍了一种在低温下制备铁氧体磁性薄膜的方法--铁氧体化学镀.利用溶液中Fe2 →Fe3 的氧化作用,直接在基体表面生成尖晶石型磁性氧化物薄膜.铁氧体化学镀反应温度很低,为在不耐热基体上制备铁氧体磁性薄膜开辟了一条新的道路.激光增强铁氧体化学镀和超声波增强铁氧体化学镀等方法可大大提高成膜质量.最后还介绍了铁氧体化学镀磁性薄膜在生物医学和一般工程领域的应用.     

添加剂粒度细化对锶铁氧体结构和磁性能的影响

研究了添加剂粒度对锶铁氧体永磁材料结构和磁性能的影响.结果表明,添加剂粒度的细化使锶铁氧体的晶粒细化,提高了磁性相的取向度,改善了磁体的综合磁性能,特别是显著改善了剩磁和最大磁能积.添加剂粒度的细化使烧结温度对磁性能的影响更敏感,降低了最佳烧结温度,有利于实现低能耗下高性能产品的生产.     

自蔓延高温合成镍铜锌铁氧体粉体研究

采用自蔓延高温合成(SHS)工艺制备了Ni0.25Cu0.25Zn0.5Fe1.96O3.94粉体,将铁氧体粉体分别在800、850、900℃进行热处理,以XRD、SEM、TG-DSC、振动样品磁强计(VSM)等手段分别对产物的物相、微观结构和磁性能进行研究.结果表明,SHS制备的NiCuZn铁氧体粉体经900℃热处理后可以转变成单一的尖晶石相,所得铁氧体粉体结构完整,矫顽力达到最小值,Hc=5 753.417 1A/m,同时饱和磁化强度达到最大值,Ms=68.34 emu/g.     

Magnetic Properties of Diluted Magnetic Nanowire

A magnetic diluted nanowire with cylindrical structure described by the Ising model is investigated. Using the effective field theory with a probability distribution technique, the influence of the dilution on the phase diagrams, susceptibility and the hysteresis loops are discussed in detail. Novel features are obtained for the thermal variations of longitudinal susceptibility and longitudinal magnetization. We have investigated the magnetic reversal of the system and have found the existence of triple hysteresis loops patterns, affected by the concentration of magnetic atoms, the temperature, and the exchange interaction between the core and the surface shell.     

Tweezing of Magnetic and Non‐Magnetic Objects with Magnetic Fields

Although strong magnetic fields cannot be conveniently “focused” like light, modern microfabrication techniques enable preparation of microstructures with which the field gradients – and resulting magnetic forces – can be localized to very small dimensions. This ability provides the foundation for magnetic tweezers which in their classical variant can address magnetic targets. More recently, the so‐called negative magnetophoretic tweezers have also been developed which enable trapping and manipulations of completely nonmagnetic particles provided that they are suspended in a high‐magnetic‐susceptibility liquid. These two modes of magnetic tweezing are complimentary techniques tailorable for different types of applications. This Progress Report provides the theoretical basis for both modalities and illustrates their specific uses ranging from the manipulation of colloids in 2D and 3D, to trapping of living cells, control of cell function, experiments with single molecules, and more.     

Magnetic Properties of Chalcopyrite-Based Diluted Magnetic Semiconductors

We calculated the chemical trends of transition metal-doped chalcopyrite DMS (diluted magnetic semiconductors) by the use of KKR–CPA–LDA method. The ferromagnetism was stable in V- and Cr-doped chalcopyrite DMS. In the case of Fe and Co doping, however, the spinglass-like state was realized. On the other hand, in the cases of Mn doped I-III-VI₂ and II-IV-V₂ type DMS, the ground state was ferromagnetic and spinglass-like, respectively.     

铁硅铝磁粉芯的磁特性研究

采用球磨制粉和模压成型方法制备了铁硅铝磁粉芯,并研究了其频率特性和直流叠加特性。结果表明,在测量的频率范围内（1～500kHz）,铁硅铝磁粉芯有效磁导率基本保持不变,而品质因数随频率的增加而增大,达到峰值后缓慢下降。在相同频率下,随着粉料粒度的减小,磁粉芯的有效磁导率降低,品质因数增加。铁硅铝磁粉芯具有良好的直流叠加特性,当直流偏磁场强度为1000e时,其有效磁导率变化率小于50％,且减小磁粉粒度可改善磁粉芯的直流叠加特性。     

磁编码器多极磁鼓材料的研究

通过分析磁编码器磁鼓的结构和制作工艺，研究采用粘结磁性材料做磁编码器用磁鼓材料。粘结磁体采用硅烷为偶联剂，环氧树脂为粘合剂。研究了不同组份的配方对磁鼓材料的影响。制备出了Ｂｒ＝１２７７Ｇｓ，Ｈｃ＝１０７９Ｏｅ，（ＢＨ）ｍａｘ＝０．５３ＭＧＯｅ的磁鼓材料。     

Tailoring of Magnetic Properties of Magnetostatically-Coupled Glass-Covered Magnetic Microwires

We report on tailoring of magnetic properties of Fe- and Co-rich microwires through magnetostatic coupling among them. We studied hysteresis loops of the arrays containing different number of the Co₆₇Fe_3.9Ni_1.5B_11.5Si_14.5M_0.6 and Fe₇₄B₁₃Si₁₁C₂ amorphous microwires. Fe₇₄B₁₃Si₁₁C₂ microwires have rectangular hysteresis loop, while Co₆₇Fe_3.9Ni_1.5B1_1.5Si_14.5M_0.6 with vanishing magnetostriction constant posses inclined hysteresis loop with low coercivity. The presence of neighboring microwire (Fe either Co-based) significantly modifies hysteresis loop of whole microwire array. In a microwire array containing Fe-based microwires, we observed splitting of the initially rectangular hysteresis loop with a number of Barkhausen jumps correlated with number of Fe-rich microwires. In Co?CCo arrays, we observed a change of inclination of overall hysteresis loop, and consequently magnetic anisotropy field under influence of the additional of Co-based microwire. In the case of mixed arrays containing Fe and Co-rich microwires, we were able to obtain irregular hysteresis loops with unusual shape. In this case, considerable increase of harmonics has been observed. Magnetic field amplitude and frequency affect the behavior of all studied arrays. Increasing the amplitude the shape of hysteresis loop of microwire array containing Fe-based microwires transforms from multi-step to single above certain magnetic field amplitude. In the array with Co-based microwires, we observe a change of coercivity. Observed dependences have been attributed by us to the magnetostatic interaction between the microwires with different magnetic domain structure. Together with the conventional method, such as thermal treatment, designing of arrays containing different types of microwires can serve for tailoring of their magnetic properties.     

磁旋转编码器多极磁鼓的研制

在分析磁骗码器的原理和结构的基础上，采用粘结磁体作磁编码器多极磁鼓记录介质材料，运用体成型工艺，研制出了多种型号的磁鼓。同时对磁鼓进行了充磁和气隙磁性能分析。     

Comparison of Magnetic Field Analysis Methods Considering Magnetic Anisotropy

The magnetic field analysis results on grain-oriented silicon steel sheet and nongrain-oriented silicon steel sheet by the isotropic method, the two-axis isotropic method, the two-axis anisotropic method, the $varphi$ anisotropic method, and the $theta_{rm HB}$ anisotropic method, which are 2-D magnetic analysis methods, are compared. In analyzing the magnetic field in the isotropic material, the isotropic method is more appropriate than the two-axis isotropic method. For the anisotropic material in which the magnetic flux density is much less than saturation magnetic flux density, the two-axis anisotropic method is more preferable than the $varphi$ anisotropic method, because the result of the two-axis anisotropic method is similar to that of the $theta_{rm HB}$ anisotropic method. However, for the analysis in high magnetic flux density near the saturation magnetic flux density, the $varphi$ anisotropic method is more suitable than the two-axis anisotropic method.      

磁性Fe3O4纳米颗粒的制备和磁性研究

讨论了一种制备磁性Fe3O4纳米颗粒的新方法，利用自行设计的反应容器，引入磁场和电场的相互作用，制得颗粒大小比较均一、分散性较好的Fe3O4纳米颗粒。通过改变反应时间、磁铁高度，得到了平均粒径为5～10nm的Fe3O4纳米颗粒，并对其进行磁特性测量。     

磁悬浮运动平台的磁场分析及优化设计

研制了一种新型磁悬浮平台,该平台定子采用无铁心式的克莱姆绕组,消除了固有齿槽效应,动子采用Halbach 磁阵列结构方式,由于平台输出推力与悬浮的稳定性主要与其气隙磁场的分布情况有直接关系,因此提高气隙磁场的正弦分布是改善其工作特性的难点和重点. 为了改善气隙磁场的分布问题,提出了一个优化磁场分布的目标函数,并采用步长加速法对平台磁场进行了优化设计,大大降低了磁场谐波分量,改善了气隙磁场分布状态. 将优化结果运用到实际的平台中,对该运动平台进行了阶跃响应实验,实验结果表明满足平台需要达到纳米级精度的要求.