制備、表征及其磁性能
(1. 江蘇科技大學(xué) 數(shù)理學(xué)院，鎮(zhèn)江 212003;
2. 江蘇大學(xué) 材料科學(xué)與工程學(xué)院，鎮(zhèn)江 212013)
摘 要: 采用溶膠−凝膠法結(jié)合靜電紡絲技術(shù)成功制備直徑為150~400 nm的Co0.5Ni0.5Fe2O4鐵氧體納米纖維，并利用TG-DTA、XRD、FTIR、FESEM、TEM和VSM對樣品進(jìn)行表征。結(jié)果表明：前驅(qū)體纖維經(jīng)450 ℃焙燒后可基本形成純相晶態(tài)的目標(biāo)產(chǎn)物Co0.5Ni0.5Fe2O4納米纖維；隨著焙燒溫度的升高，纖維直徑逐漸減小，晶粒尺寸逐漸增大，纖維表面粗糙度加強(qiáng)，其微觀形貌由多孔結(jié)構(gòu)向項鏈狀結(jié)構(gòu)轉(zhuǎn)變；所制得的Co0.5Ni0.5Fe2O4納米纖維的飽和磁化強(qiáng)度由450 ℃時的35.8 A·m2/kg單調(diào)增加到1 000 ℃時的80.2 A·m2/kg，而矯頑力呈現(xiàn)先增大后減小的趨勢，在550 ℃附近時達(dá)到最大值，意味著其單疇臨界尺寸約為30 nm，且發(fā)現(xiàn)在單疇尺寸范圍內(nèi)，矯頑力與平均晶粒尺寸的0.7次方成正比，與隨機(jī)各向異性模型所預(yù)測的結(jié)果基本吻合。此外，低溫(77 K)磁測量顯示，與室溫相比，樣品的矯頑力和剩余磁化強(qiáng)度均大幅提高，但飽和磁化強(qiáng)度明顯下降。
關(guān)鍵字: Co-Ni鐵氧體；納米纖維；靜電紡絲；磁性能
magnetic properties of Co0.5Ni0.5Fe2O4 nanofibers
（1. School of Mathematics and Physics, Jiangsu University of Science and Technology, Zhenjiang 212003, China;
2. School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013, China）
Abstract:Co0.5Ni0.5Fe2O4 nanofibers with diameter of 150–400 nm were fabricated by sol-gel method combined with electrospinning technology. The as-prepared fiber samples were characterized by means of TG-DTA, XRD, FTIR, FESEM, TEM and VSM techniques. The results show that the pure resultant products with spinel structure are basically formed after calcining the precursor fibers at 450 ℃ for 2 h. With the increase of the calcination temperature, the fiber diameters decrease and the mean size (D) of Co0.5Ni0.5Fe2O4 grains within the fibers gradually increase. As a result, the fiber surface morphology gradually transforms from a porous structure to a necklace-like structure. The saturation magnetizations (Ms) of the obtained Co0.5Ni0.5Fe2O4 nanofibers monotonously increase from 35.8 A·m2/kg at 450 ℃ to 80.2 A·m2/kg at 1 000 ℃ while the corresponding coercivities (Hc) initially increase and then decrease, and reaches the maximum value at about 550 ℃, which indicates that the single-domain critical size of Co0.5Ni0.5Fe2O4 in the form of nanofibers is around 30 nm. Hc of the nanofibers varies as D0.71 in a D range below the single-domain critical size, which is in good agreement with the result predicted on the basis of the random anisotropy model. In addition, the magnetic properties measured at low temperature (77 K) show the substantial enhancements in both coercivity and remanent magnetization and a relatively obvious reduction in saturation magnetization compared to the corresponding room-temperature values.
Key words: Co-Ni ferrite; nanofibers; electrospinning; magnetic properties
