共查询到19条相似文献,搜索用时 343 毫秒
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采用溶胶-凝胶法及脱脂棉作为模板制得絮状掺杂锶铁氧体(SiLaxFe12-xO19(x=0.5)),通过引入不同种类表面活性剂,制备出M型掺杂锶铁氧体(SiLaxFe12-xO19(x=0.5))/聚吡咯(PPy)复合吸波材料。结果表明:采用表面活性剂十二烷基苯磺酸钠(C18H29NaO3S)合成的吸波材料的饱和磁化强度(emu/g)、矫顽力(Oe)及剩余磁化强度(emu/g)要高于使用阳离子表面活性剂。γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH-570)合成的吸波材料磁化性能明显优于阴/阳离子表面活性剂,但阴/阳离子表面活性剂磁损耗比较高。最佳频率匹配范围为800~1000MHz。 相似文献
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采用溶胶-凝胶法及脱脂棉作为模板制得絮状掺杂锶铁氧体(SiLaxFe12-xO19(x=0.5)),通过引入不同种类表面活性剂,制备出M型掺杂锶铁氧体(SiLaxFe12-xO19(x=0.5))/聚吡咯(PPy)复合吸波材料。结果表明:采用表面活性剂十二烷基苯磺酸钠(C18H29NaO3S)合成的吸波材料的饱和磁化强度(emu/g)、矫顽力(Oe)及剩余磁化强度(emu/g)要高于使用阳离子表面活性剂。γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH-570)合成的吸波材料磁化性能明显优于阴/阳离子表面活性剂,但阴/阳离子表面活性剂磁损耗比较高。最佳频率匹配范围为800~1000MHz。 相似文献
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《功能材料》2021,52(9)
利用溶胶-凝胶法,在1 200~1 400℃烧结制备了Zr~(4+)-Ni~(2+)共掺杂钡铁氧体Ba(ZrNi)_xFe_(12-2x)O_(19)(x=0.6~0.9),研究了掺杂量及烧结温度对M型钡铁氧体晶相结构、微观形貌、电磁性能和吸波性能的影响。结果表明随着锆镍掺杂量和烧结温度的增加,样品的晶体结构和化学成分不发生变化,都形成了片状的单相锆镍掺杂钡铁氧体。晶粒尺寸随掺杂量增加几乎不变化而随烧结温度提高逐渐从100~300 nm增加到1~2 mm。所有样品中均可观察到多自然共振峰,自然共振强度随掺杂量的增加整体呈下降的趋势,而介电常数随烧结温度升高会显著增加。最终,1 400℃烧结的掺杂量x=0.6的样品可获得最优异的吸波性能,在匹配厚度3.25 mm下,最小反射损耗为-16.4dB,同时有效吸波频宽可达5.22 GHz(8.62~13.84 GHz)。 相似文献
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采用溶胶-凝胶自蔓延燃烧法制备稀土Ce^(3+)掺杂纳米CoFe_2O_4,使用XRD、EDS、FT-IR、TEM和PNA等手段对产物的物相组成、形貌和电磁参数进行表征和分析,研究了掺杂稀土Ce^(3+)对纳米CoFe_2O_4的结构和吸波性能的影响。结果表明:所制备出的CoFe_2O_4和CoFe_(1.7)Ce_(0.3)O_4具有尖晶石型结构,其粒径分别为70 nm和60 nm;在0~6 GHz频率范围内CoFe_(2-x)Ce_xO_4的吸波性能比纯CoFe_2O_4有了很大的提高,当x=0.3时吸波性能最佳,在5030 MHz处最大吸收峰值为-27.6 d B,-5 d B频宽为1.6GHz。 相似文献
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目前,鲜见关于锶铁氧体化学镀Ni-Co合金吸波特性的报道,且关于吸波材料特性的研究集中于6~18 GHz波段,未有对0~6 GHz波段的报道。自制了SrFe12O19粉体,采用铜氨溶液及银氨溶液对其敏化活化后化学镀Ni-Co合金,并对银氨溶液敏化活化制备的试样进行热处理。采用X射线衍射仪、能谱仪及透射电镜分析复合材料的结构、成分及形貌;采用振动样品磁强计测试了其磁性能;采用网络分析仪分析其吸波性能。结果表明:化学镀后,SrF12O19表面已成功镀覆上了较均匀的Ni-Co合金镀层,银氨溶液敏化活化后的化学镀Ni-Co合金磁性能及吸波性能优于铜氨溶液敏化活化的;银氨溶液敏化活化制备的复合材料于420℃热处理1 h后,饱和磁化强度(Ms)增加至123.55(A·m2)/kg,比纯SrF12O19增加了71.96(A·m2)/kg,0~6 GHz波段的吸波性能大幅提升,最大吸收值在5 982.0 MHz处达-7.75 dB。 相似文献
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采用化学共沉淀法制备了纳米Ni0.5Zn0.5CexFe2-xO4(x=0,0.005,0.01,0.015)铁氧体吸波材料,用AV3618型微波矢量网络分析仪测试了样品在8.2~12.5GHz范围内的微波吸收特性,实验结果表明:稀土元素铈的含量影响材料的吸波性能,当x=0.01时, 纳米Ni0.5Zn0.5CexFe2-xO4铁氧体的吸波性能最佳.对于Ni0.5Zn0.5Ce0.01Fe1.99O4铁氧体吸波材料,当涂层厚度为1mm时,在测试频段内有三个吸收峰,在8.8GHz处,其最大吸收衰减量为15.4dB,10 dB以上带宽达3.8GHz,适量掺杂稀土元素铈是提高镍锌铁氧体吸波材料性能的一种有效途径. 相似文献
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采用溶胶-凝胶工艺制备了Sr_(1-x)La_xCo_(0.3)Ti_(0.3)Fe_(11.4)O_(19)铁氧体,利用XRD和微波网络矢量分析仪对其相成分和吸收特性进行研究,实验发现:适量的掺杂稀土镧时能够增大吸收频带宽度,改善吸收性能;当x=0.3时,最大吸收可达42.37dB,10dB带宽达2.90GHz,20dB带宽达2.33GHz,这非常有利于作为高频吸波材料。通过对Sr_(0.7)La_(0.3)Co_(0.3)Ti_(0.3)Fe_(11.4)O_(19)铁氧体烧结温度的分析,发现在800℃烧结,晶粒只有40nm左右,吸收性能最好。 相似文献
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采用化学共沉+高温助熔工艺制备了铁氧体Ba(Zn(1-x)Cox)2Fe16O27粉体,然后用模压法制备了铁氧体粉体/环氧树脂复合材料板,采用同轴电缆法测定了复合材料的电磁参数。研究表明,随着铁氧体中Co含量增加,铁氧体主相由BaZn2Fe16O27转变成Ba-Co2Fe16O27,材料磁损耗逐渐加强,复合材料与空气的电磁匹配特性在频率低于12GHz时较好。然后将M-玻璃纤维/环氧树脂复合材料置于铁氧体粉体/环氧树脂复合材料前端组合成多层复合材料结构,复合材料板与空气的电磁匹配性能和吸波性能都有很大提高。数据如下:当复合材料结构中x=0.75铁氧体吸波层厚度为2.0mm,结构总厚度5.3mm时,复合结构反射系数R的绝对值在2~8GHz时4dB、在8~18GHz时10dB的吸波性能。 相似文献
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Nd1-xSrxMn1-yCuyO3/NiFe2O4复合体系的磁电阻效应研究 总被引:1,自引:0,他引:1
采用溶胶-凝胶法制备了Nd1-xSrxMn1-yCuO3(x=0.33、0.2,y=0.05、0.2)微粉,平均粒径约为150nm;采用化学共沉淀法制备了NiFe2O4;微粉,平均粒径为70nm;将两种粉体充分混合、压成片状后烧结成多晶块体复合材料。经测量NiFe2O4质量百分比为30%的Nd0.67Sr0.33Mn0.8Cu0.2O3/NiFe2O4复合样品在1.8T磁场作用下,在293~315K温度范围内磁电阻MR基本保持在-13.6%.说明在室温附近温度稳定性较好。 相似文献
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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. 相似文献
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采用简单的自燃法, 以去离子水为溶剂, 柠檬酸为螯合剂, 硝酸盐为原料制备了金属钠掺杂的(Na_xCa_(1-x))_3Co_4O_9热电材料前驱粉.前驱粉经煅烧、球磨、冷压、烧结等工艺获得块体材料.通过X射线衍射, 扫描电镜观察等方法对样品的结构与形貌进行了分析表征.在573~1073K温度区间内, 测试了材料的电阻率和Seebeck系数.研究表明,试样(x=0.15)在973K时的电阻率可达ρ=5.899mΩ·cm,Seebeck系数S=185μV/K,热电转换功率因子值p=5.802×10~(-6)W/(m·K2). 相似文献
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By laser heated pedestal growth method,Bi_2Sr_2CaCu_2O_(8+δ) as-grown fibers with differentmorphologies were solidified in non-equilibriumcondition at the rates of 0.1~14mm/min.At lowrates,a(Sr_(1-x)Ca_x)CuO_2 phase with long andstraight strips in shape and a white Cu-rich phasehaving a morphology of globular shape were found.With the increase of solidification rates,the phase(Sr_(1-x)Ca_x)CuO_2 becomes thinner and the Cu-richphase becomes smaller and dispersive.When thesolidification rates were last.another unstablephase(Sr_(1-x)Ca_x)Cu_2O_3 occurred.In fact,the tran-sition of the semiconductive as-grown fiber to thesuperconductor is a peritectoid reaction influencedby the annealing temperature and time. 相似文献
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A series of YTi(Fe_(1-x)_(11)alloy withx=0.00,0.01,0.03,0.04,0.05,0.07 and 0.10 hasbeen investigated by measurement of the structuralproperties and ~(57)Fe Mssbauer experiments.Thepure ThMn_(12)-structure phase exists at x≤0.03 andis absent at x>0.03.The reasons for lower satura-tion magnetization and lower energy product of theThMn_(12)-structure compounds were given.Thecrystal structure relations 相似文献
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采用溶胶-凝胶旋涂法制备了纳米Co1-xMg xFe2O4/SiO2(x = 0, 0.2, 0.4, 0.6, 0.8) 复合薄膜。利用XRD、SEM、原子力显微镜、振动样品磁强计对薄膜的结构、形貌和磁性进行了分析, 研究了Mg2+含量对样品结构和磁性的影响。结果表明, 样品中Co1-xMg xFe2O4具有尖晶石结构, 晶粒尺寸在38~46 nm之间。随着Mg2+含量的增加, Co1-xMg xFe2O4的晶格常数减小, 样品的饱和磁化强度减小, 矫顽力先增大后减小。样品Co0.4Mg0.6Fe2O4/SiO2垂直和平行膜面的矫顽力分别为350.7 kA·m-1和279.4 kA·m-1, 剩磁比分别为67.2%和53.9%, Co1-xMg xFe2O4/SiO2复合薄膜具有较明显的垂直磁各向异性。 相似文献
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Singh RK Srinivasan A Kothiyal GP 《Journal of materials science. Materials in medicine》2009,20(Z1):S147-S151
Magnetic bioglass ceramics (MBC) are being considered for use as thermoseeds in hyperthermia treatment of cancer. While the bioactivity in MBCs is attributed to the formation of the bone minerals such as crystalline apatite, wollastonite, etc. in a physiological environment, the magnetic property arises from the magnetite [Fe3O4] present in these implant materials. A new set of bioglasses with compositions 41CaO x (52-x)SiO2 x 4P2O5 x xFe2O3 x 3Na2O (2 < or = x < or = 10 mol% Fe2O3) have been prepared by melt quenching method. The as-quenched glasses were then heat treated at 1050 degrees C for 3 h to obtain the glass-ceramics. The structure and microstructure of the samples were characterized using X-ray diffraction and microscopy techniques. X-ray diffraction data revealed the presence of magnetite in the heat treated samples with x > or = 2 mol% Fe2O3. Room temperature magnetic property of the heat treated samples was investigated using a Vibrating Sample Magnetometer. Field scans up to 20 kOe revealed that the glass ceramic samples had a high saturation magnetization and low coercivity. Room temperature hysteresis cycles were also recorded at 500 Oe to ascertain the magnetic properties at clinically amenable field strengths. The area under the magnetic hysteresis loop is a measure of the heat generated by the MBC. The coercivity of the samples is another important factor for hyperthermia applications. The area under the loop increases with an increase in Fe2O3 molar concentration and the. coercivity decreases with an increase in Fe2O3 molar concentration The evolution of magnetic properties in these MBCs as a function of Fe2O3 molar concentration is discussed and correlated with the amount of magnetite present in them. 相似文献