掺杂对棒状纳米SrFe_(12)O_(19)形貌和性能的影响

以FeCl2为原料,利用化学沉淀法制备了针状纳米α-FeOOH中间体,并通过柠檬酸法在针状纳米α-FeOOH表面包裹锶的柠檬酸配合物,煅烧后形成的棒状纳米SrFe12O19并分别在共沉淀和溶胶-凝胶2个不同过程中对纳米SrFe12O19进行镧掺杂。采用XRD,TEM和振动样品磁强计(VSM)对SrFe12O19及掺杂锶铁氧体的结构、形貌及磁性能进行了表征。结果表明:沉淀法和柠檬酸法相结合后制得的针状前驱体于900℃煅烧后可制得平均直径为40nm,长径比为15～20的棒状纳米SrFe12O19。在沉淀过程中对前驱体进行掺杂后制得的SrLaxFe12-xO19较同温度时在溶胶-凝胶过程中进行掺杂制得样品的长径比有所增加,进而使得SrLaxFe12-xO19的各向异性变大,磁性能增加,且在沉淀过程中掺杂镧后,样品的矫顽力和饱和磁化强度达到最大值时,x值明显大于溶胶-凝胶过程中进行掺杂制得的棒状SrLaxFe12-xO19。利用共沉淀法掺杂后,当x=0.15时制备的样品的矫顽力最大为6179.1Oe,此时样品的饱和磁化强度和剩余磁化强度分别65.7和38.4emu·g-1。当x=0.2时制备的样品的饱和磁化强度达到最大值为67.3emu·g-1,样品的矫顽力为5852.7Oe。

Effect of Doping on Morphology and Properties of Rod-Like Nano-SrFe12O19

FeCl2 was used for preparing needle-like α-FeOOH intermediate by chemical precipitation method. Then the needle-like α-FeOOH was enwrapped by the complex of the citrate acid and Sr2+ by citrate acid method. The rodlike nano-SrFe12O19 was obtained after the calcination of enwrapped α-FeOOH precursor. La3+ was doped into the nano-SrFe12O19 in the coprecipitation processes and sol-gel processes, respectively. The phase, morphology, particle size, and the magnetic properties of samples were studied by XRD, TEM and vibrating sample magnetometer (VSM).The results show that the rod-like SrFe12O19 with an average diameter of 40 nm and the slenderness ratio of 15～20 is obtained by the combination of the precipitation method and citrate acid method. It is also found that the rod-like SrLaxFe12-xO19 obtained by La doping in the precipitation process is with smaller particles and higher slenderness ratio, x values higher than that by doping in the sol-gel process,resulting in the increased shape anisotropy and magnetic properties. As x=0.15, the optimum coercivity, saturation magnetization, and residual magnetization for the samples by doping La in the precipitation process are 6 179.1Oe, 65.7 and 38.4 emu·g-1, respectively. As x=0.2, the maximal saturation magnetization for the sample is 67.3 emu·g-1, and the coereivity is 5852.7Oe.