Ni_(0.5)Zn_(0.5)Fe_2O_4铁氧体的制备及其电磁损耗性能

以Zn(NO3)2.6H2O、Ni(NO3)2.6H2O和Fe(NO3)3.9H2O及柠檬酸为原料,采用溶胶-凝胶法制备前驱体,在1 200℃下煅烧3 h合成ZnFe2O4和Ni0.5Zn0.5Fe2O4铁氧体粉体。利用差热分析、X射线衍射、扫描电镜、透射电镜和红外光谱等测试手段对产物进行分析和表征。结果表明:ZnFe2O4和Ni0.5Zn0.5Fe2O4属于立方晶系尖晶石结构,结晶完整,晶粒大小在100 nm左右。在0.2~1.8 GHz的频率下对产品进行了电磁损耗性能测试,发现Ni0.5Zn0.5Fe2O4具有较好的电磁损耗特性。     

复合纳米纤维静电纺丝法的制备及其磁性

以聚乙烯吡咯烷酮（PVP）和金属盐为原料,利用静电纺丝法成功制备出了摩尔比为1：1的SrTiO3-SrFe12O19磁电复合纳米纤维。并通过FT-IR,XRD,SEM和VSM等技术对纤维前驱体及其产物的结构、热处理产物的物相、形貌及磁性能进行了表征。结果表明,样品经900℃焙烧2h后,即可得到纯的SrTiO3和SrFe...     

Fabrication and Magnetic Property of One-dimensional SrTiO3/SrFe12O19 Composite Nanofibers by Electrospinning

The composite nanofibers of SrTiO3/SrFe12O19 with a molar ratio of 1:1 and diameter about 120 nm were prepared by electrospinning. Effects of calcination temperature on the formation, crystallite size, morphology and magnetic property were studied by infrared spectroscopy, X-ray diffraction, scanning electron microscopy and vibrating sample magnetometer. The binary phase of strontium ferrite and titanate was formed after being calcined at 900℃ for 2 h and the composite nanofibers were fabricated from nanograins of SrTiO3 about 24 nm and SrFe12O19 around 33 nm. The crystallite sizes for the nanofibers increase with increasing calcination temperature and the addition of SrTiO3 has an obvious suppression effect on SrFe12O19 grain growth. The specific saturation magnetization and remanence tend to increase with the crystallite size. With increasing calcination temperature from 900 to 1050℃, the coercivity increases initially, achieving a maximum value of 520.2 kA·m-1 at 950℃, and then shows a reduction tendency.     

Fabrication and magnetic property of BaSm(x)Fe(12-x)O19 (x < or = 0.4) nanofibers

BaSm(x)Fe(12-x)O19 (x < or = 0.4) ferrite nanofibers were prepared by sol-gel method from starting reagents of metal salts and citric acid. These nanofibers were characterized by TG-DTA, FTIR, SEM, XRD and VSM. These results show that the BaSm(x)Fe(12-x)O19 (x < or = 0.4) ferrite nanofibers were obtained subsequently from calcination at 750 degrees C for 1 h. The BaSm(x)Fe(12-x)O19 (x < or = 0.4) microstructure and magnetic property are mainly influenced by chemical composition and heat-treatment temperature. The grain sizes of BaSm0.3Fe11.7O19 ferrite nanofibers are in a nanoscale from 40 nm to 62 nm corresponding to the calcination temperature from 750 degrees C to 1050 derees C. The saturation magnetization of BaSm(x)Fe(12-x)O19 ferrite nanofiber calcined at 950 degrees C for 1 h initially decreases with the Sm content from 0 to 0.3 and then increases with a further Sm content, while the coercivity exhibits a continuous increase from 348 kA x m(-1) (x = 0) to 427 kA x m(-1) (x = 0.4). The differences of magnetic properties are attributed to lattice distortion and enhancement for the anisotropy energy.     

Ni0.5Zn0.5Nd0.02Fe1.98O4-聚苯胺纳米复合材料的制备及电磁性能（英文）

在Ni0.5Zn0.5Nd0.02Fe1.98O4纳米粒子表面原位聚合苯胺制备了Ni0.5Zn0.5Nd0.02Fe1.98O4-聚苯胺(PANI)纳米复合材料.铁氧体含量为0%、15%和30%样品的结构、形貌和电磁性能分别采用X射线衍射仪(XRD)、透射电子显微镜(TEM)和HB8510B网络分析仪进行了研究.结果表明,聚苯胺包覆层对Ni0.5Zn0.5Nd0.02Fe1.98O4的结晶度有一定影响.在X波段(8.2～12.4 GHz),复介电常数的实部随铁氧体含量的增加而减小,虚部随铁氧体含量的增加而增大.复磁导率的实部和虚部都随铁氧体含量的增加而增大.     

Microwave properties of polymer composites containing combinations of micro- and nano-sized magnetic fillers

We investigated the microwave absorbing properties of composite bulk samples with nanostructured and micron-sized fillers. As magnetic fillers we used magnetite powder (Fe3O4 with low magnetocrystalline anisotropy) and strontium hexaferrite (SrFe12O9 with high magnetocrystalline anisotropy). The dielectric matrix consisted of silicone rubber. The average particle size was 30 nm for the magnetite powder and 6 micro/m for the strontium hexaferrite powder. The micron-sized SrFe12O19 powder was prepared using a solid-state reaction. We investigated the influence of the filler concentration and the filler ratio (Fe3O4/SrFe12O19) in the polymer matrix on the microwave absorption in a large frequency range (1 / 18 GHz). The results obtained showed that the highly anisotropic particles become centers of clusterification and the small magnetite particles form magnetic balls with different diameter depending on the concentration. The effect of adding micron-sized SrFe12O19 to the nanosized Fe3O4 filler in composites absorbing structures has to do with the ferromagnetic resonance (FMR) shifting to the higher frequencies due to the changes in the ferrite filler's properties induced by the presence of a magnetic material with high magnetocrystalline anisotropy. The two-component filler possesses new values of the saturation magnetization and of the anisotropy constant, differing from those of both SrFe12O1919 and Fe3O4, which leads to a rise in the effective anisotropy field. The results demonstrate the possibility to vary the composite's absorption characteristics in a controlled manner by way of introducing a second magnetic material.     

静电纺丝法制备的Co0.6Ni0.3Cu0.1Fe2O4和Co0.6Ni0.3Zn0.1Fe2O4纳米纤维的结构及磁性能

采用静电纺丝技术制备出表面光滑、直径均匀的Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4/PVP和Co_(0.6)Ni_(0.3)Zn_(0.1)Fe_2O_4/PVP纳米纤维前驱丝,经500~900℃煅烧后得到Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4和Co_(0.6)Ni_(0.3)Zn_(0.1)Fe_2O_4纳米纤维。用TG-DSC、XRD、SEM及VSM现代测试分析手段对Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4和Co_(0.6)Ni_(0.3)Zn_(0.1)Fe_2O_4纳米纤维的结构、形貌及磁学性能进行测试表征。结果表明:在空气气氛中经500~900℃煅烧后可得到纯尖晶石相、结晶度良好的纳米纤维或短纤维;当温度为700℃时,Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4和Co_(0.6)Ni_(0.3)Zn_(0.1)Fe_2O_4纳米纤维的形貌细长而光滑且直径相对均匀,大约为80nm;此时Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4纳米纤维则保有较高的剩磁比(M_r/M_s)及矫顽力,分别为0.56和1 088.87Oe。在500℃、600℃、700℃、800℃、900℃煅烧后,Co_(0.6)Ni_(0.3)Zn_(0.1)Fe_2O_4纳米纤维的饱和磁化强度分别比Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4纳米纤维增大了14.5%、7%、16%、10.7%、8%,而矫顽力则分别降低了38%、51%、50%、46%、46.7%。两种纳米纤维的饱和磁化强度及矫顽力存在差异,为CoNi铁氧体在电磁方面的应用提供了很好的参考。     

Co_(0.5)Zn_(0.5)Fe_2O_4/SiO_2磁性纳米复合粉体的制备

采用溶胶-凝胶法以正硅酸乙酯和金属硝酸盐分别作为SiO2和铁氧体的前驱体成功制得Co0.5Zn0.5-Fe2O4/SiO2磁性纳米复合粒子.利用XRD、DSC-TG、Raman和SEM研究了热处理温度和酸添加量对样品晶体结构和晶粒尺寸的影响,并用谢乐公式估算平均晶粒尺寸.最后用振动样品磁场计(VSM)对样品的磁性能进行检测.结果表明,随热处理温度的升高,样品由非晶态转变成SiO2基体中结晶较完整的尖晶石结构的单相铁氧体纳米晶,晶粒尺寸为12.65nm.晶粒尺寸随热处理温度的升高和酸添加量的增加不断变大.对材料的磁性能的研究结果表明,合成的纳米Co0.5Zn0.5Fe2O4/SiO2,其比饱和磁化强度为9.17emu/g,矫顽力为67Oe.     

Preparation of a new nanosized As2O3/Mn0.5Zn0.5Fe2O4 thermosensitive magnetoliposome and its antitumor effect on MDA_MB_231 cells

The purpose of our research is to explore the preparation method of a new nanosized As2O3/Mn0.5Zn0.5Fe2O4 thermosensitive magnetoliposome and study its antitumor effect on MDA_MB_231 cells. The liposomes prepared by the method of rotatory film and high-pressure homogenization were detected by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), nano-particles detector, atom fluorescence spectrophotometer and differential scanning calorimetry (DSC). The therapeutic effects of the nanosized thermosensitive magnetoliposomes combined hyperthermia on human MDA_MB_231 cells in vitro were evaluated by MTT assay and flow cytometry assay. The results indicated that the nanosized As2O3/Mn0.5Zn0.5Fe2O4 thermosensitive magnetoliposomes were prepared successfully. The liposomes were spherical, and most of them were single-room. The exat average diameter of them was 103.8 nm. EDS showed each nanosized As2O3/Mn0.5Zn0.5Fe2O4 thermosensitive magnetoliposome contained P, Mn, Zn, Fe, and As elements, and this proved liposomes have successfully entrapped As2O3 and Mn0.5Zn0.5Fe2O4. The encapsulation ratio of As2O3 detected by atom fluorescence spectrophotometer was 82.16%. The result of heating test showed that Mn0.5Zn0.5Fe2O4 can serve as a heating source upon alternating magnetic field (AMF) exposure leading the nanosized thermosensitive liposomes to reach its phase transition temperature (42.52 degrees C) and release As2O3. MTT assay and flow cytometry assay revealed that the therapeutic effect of the nanosized As2O3/Mn0.5Zn0.5Fe2O4 thermosensitive magnetoliposomes combined with hyperthermia upon AMF on MDA_MB_231 cells was much better than other groups.     

Synthesis, Characterization and Electromagnetic Studies on Nanocrystalline Co0.5Zn0.5Fe2O4 Synthesized by Polyacrylamide Gel

Nanocrystalline Co0.5Zn0.5Fe2O4 ferrite was synthesized by polyacrylamide gel method. The electromagnetic and microwave absorption properties of the ferrite were investigated. The results indicated that calcining temperature of the ferrite had a significant influence on the effective properties of the ferrite. When the calcining temperature was 500, 600 and 700℃, the average size of particles was 10, 30 and 80 nm, respectively. The dielectric loss （ε″） and magnetic loss （μ″） of the ferrite was around 0.65 and 0.29 at 8.2 GHz, respectively. Microwave absorption properties of the ferrites were simultaneously influenced due to the strong correlation between reflection loss and electromagnetic parameters of the ferrite.     

核壳结构SrFe12O19NiFe2O4复合纳米粉体的吸波性能

以Fe(NO₃)₃、 Ni(NO₃)₂和Sr(NO₃)₂为主要原料, 通过两步柠檬酸盐溶胶-凝胶法, 制备出核-壳结构SrFe₁₂O₁₉-NiFe₂O₄磁性纳米复合粉体。采用XRD、 TEM、 VSM及矢量网络分析仪对合成的粉体的结构、 形貌及吸波性能进行了分析研究。结果表明, 复合粉体的相结构与NiFe₂O₄含量有关, 当SrFe₁₂O₁₉与NiFe₂O₄的质量比为1∶2、 烧结温度为1050℃时, 复合纳米粉体的相与NiFe₂O₄接近, 核-壳结构SrFe₁₂O₁₉-NiFe₂O₄纳米复合粉体的饱和磁化强度(M_s)(51.4 emu/g)比单体SrFe₁₂O₁₉纳米粉体 (42.6 emu/g)的大; 但矫顽力(H_c) (336 Oe)比单体SrFe₁₂O₁₉纳米粉体的小, 在SrFe₁₂O₁₉ 与NiFe₂O₄的矫顽力5395～160 Oe之间。在频率为8～18 GHz范围内, 微波吸收逐渐增强, 当频率为12 GHz时, SrFe₁₂O₁₉-NiFe₂O₄纳米复合粉体的微波吸收达到最大值-9.7 dB, 是一种性能优良的吸波材料。      

回流法制备纳米 NiZn铁氧体及成相机理研究

采用回流法合成了纳米级的尖晶石相NiZn铁氧体．通过XRD测试和回流液反应过程中pH值变化分析，确定了最佳的回流反应时间为6h，同时对回流反应的机理进行了初步的研究．透射电镜结果显示NiZn铁氧体的颗粒为10-30nm，高分辨透射电镜分析表明回流法合成的铁氧体为单一尖晶石相．用VSM研究了纳米NiZn铁氧体粉料的软磁特性．     

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。     

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.     

La掺杂纳米晶Ni-Zn铁氧体的制备及电磁性能

采用高分子凝胶法制备了Ni0.5Zn0.5LaxFe2-xO4（x=0,0.02,0.05和0.08）纳米晶铁氧体.采用X射线衍射仪（XRD）、透射电镜（TEM）和HP8510网络分析仪分别对其结构、形貌和电磁性能进行了研究.结果表明,当x=0,0.02和0.05时,所得粉体为纯立方晶系尖晶石结构.Ni0.5Zn0.5Fe2O4粉体平均粒径为70nm.随着La离子掺杂量的增加,红外光谱中550cm-1处吸收峰向高波数移动,420cm-1处吸收峰向低波数移动.La离子的掺杂对Ni-Zn铁氧体的电磁性能有一定的影响.在X波段,与Ni0.5Zn0.5Fe2O4铁氧体相比,掺杂La的Ni-Zn铁氧体的tanδm值降低,tanδε值升高.Ni0.5Zn0.5La0.02Fe1.98O4铁氧体的tanδε平均值为0.616.     

Magnetic and catalytic properties of Cu0.5Zn0.5Fe2O4 nanocrystallite powders

Cu0.5Zn0.5Fe2O4 nanocrystallite powders (average size 13 nm) were synthesized from Cu-Zn spent catalyst (fertilizers) industries and ferrous sulfate wastes formed during iron and steel making. Cu-Zn catalyst (22.4% Cu and 26.4% Zn) was chemically treated with sulfuric acid at temperature 80 degrees C for 1 hr for the complete dissolving of copper and zinc into sulfate solution, then the produced solution was mixed with stoichiometric ratio of ferrous sulfate and the mixture was chemically precipitated as hydroxides followed by hydrothermal processing. The parameters affecting the magnetic properties and crystallite size of the produced ferrites powder e.g., temperature, time, and pH were systemically studied. X-ray diffraction analysis was used in order to determine the average crystallite size and phase identifications of the produced powder. The magnetic properties were studied by vibrating sample magnetometry. The results showed that the average crystallite size of the powder decreased for the ferrites powder formed at 150 degrees C and then increased by increasing the temperature to 200 degrees C. Interestingly, the saturation magnetization (Bs), remanent magnetization (Br) and coercive force (Hc) were 25.03 emu/g, 0.71 emu/g, and 4.83 Oe, respectively at hydrothermal temperature 150 degrees C for 24 hr and changed to 16.38 emu/g, 0.3864 emu/g, and 5.2 Oe at 150 degrees C and 72 hr. The produced nanoferrite powders are used for studying the catalytic activity of CO conversion to CO2 at different temperatures, pH and times. The maximum conversion (82%) is obtained at temperature 150 degrees C for 24 hrs and pH 12.     

晶化温度对纳米镍锌铁氧体吸波性能的影响

本文通过水热法制备纳米Ni0.6Zn0.4Fe_2O_4,研究了晶化温度对样品纯度、粒度、形貌及电磁波吸收性能的影响。结果表明:当晶化温度为160℃时,粒子形貌不规则,并未完全形成Ni0.6Zn0.4Fe_2O_4;纯相Ni0.6Zn0.4Fe_2O_4的形成温度为180℃,粒子呈类球形结构,分布均匀,平均粒径约为20~25nm;但温度高于180℃时,尖晶石结构不稳定性增加,有杂相α-Fe2O3生成,粒子明显增大,团聚严重。晶化温度180℃,晶化时间8h制得的纯相纳米Ni0.6Zn0.4Fe_2O_4吸波性能最好,损耗因子在3.5GHz处达到最大值为1.08。利用共振损耗理论对纳米镍锌铁氧体的吸波机理进行分析,通过Helmholtz方程推导出纳米镍锌铁氧体本征振动频率的计算公式。     

热分解法制备Ni_(0.5)Zn_(0.5)Fe_2O_4纳米颗粒

采用热分解法制备Ni_(0.5)Zn_(0.5)Fe_2O_4纳米颗粒,研究表面活性剂用量、回流温度和回流时间对产物尺寸、形貌以及分散性的影响。通过X射线衍射仪(XRD)、透射电子显微镜(TEM)和振动样品磁强计(VSM)对样品的结构、形貌与磁性能进行了表征。结果表明:增加表面活性剂的用量,产物的粒径减小,分散性明显提高,而提高回流温度和延长回流时间则会使产物粒径增加,但粒径分布也会变宽。在三辛基氧化膦(TOPO)用量为0.6mmol,260℃回流1h条件下制备产物的饱和磁化强度为49.38A·m2/kg,矫顽力为7143.20A/m,剩余磁化强度为5.76A·m2/kg,表现为亚铁磁性。     

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。     

超声场下导电聚苯胺/纳米铁氧体吸波涂层的制备及其吸波性能

导电聚苯胺/纳米铁氧体复合吸波材料具有吸波能力强,质量轻等特点.采用乳液聚合法以苯胺为单体、十二烷基苯磺酸为掺杂剂、过硫酸铵为氧化剂,在超声场下制备导电聚苯胺粉体;将其与纳米Ni0.5Zn0.5Fe2O45及纳米Co0.5Zn0.5Fe2O4一起用原位合成法制备了复合吸波涂层.结果表明:制备的吸波涂层在17.9,15.9,22.3 GHz时分别具有最大反射损耗-10.0,-15.9,-39.9 dB,2种复合涂层拓展了波段,提高了对电磁渡的吸收效果.