| Porous anodic alumina (PAA) membrane has a unique uniform nano-columnar pore array structure, it can be used as the template when electrodeposite the magnetic metal nanowires in ionic liquid. The obtained magnetic metal nanowire is a kind of ultra-high density magnetic recording media with good perpendicular magnetic anisotropy. This has great importance for developing new high-density magnetic storage materials.In this paper, porous anodic alumina template was prepared in the electrolyte of 0.3 mol·L-1 oxalic acid with using two anodic oxidation (one hour the first time, then two hour continuously). Then potential was steped down to make the barrier layer thinner. The anodic oxidation of porous anodic alumina template was puted in 2g·L-1 ferric chloride solution saturated oxalic acid solution 5.5 hours. Then the Sm-Co alloy nanowire array film and Tb-Fe-Co alloy nanowire arrays film was prepared using the anodic oxidation of porous anodic alumina as cathode, ionic liquid [BMIM] BF4 as electrolyte.The nanowires in Sm-Co alloy nanowire array film have a high content of samarium, which can reach 90% by weight. The nanowire has a length about 2μm, 70nm in diameter, which was consistent with pore size of the porous anodic alumina template, there are two main crystal structure in Sm-Co alloy nanowire array film, SmCo5 and Sm2Co17.To obtain a high content of Tb in Tb-Fe-Co nanowire, the composition of electrolyte was determined by orthogonal experiments, the result is: the concentration of Fe(BF4)2 is 0.75 mol·L-1, the concentration of Co(BF4)2 is 0.75 mol·L-1, the concentration of Tb(BF4)3 is 1.5 mol·L-1, the concentration of 1,4 - butynediol is 2g·L-1, in this condition, the content of Tb in Tb-Fe-Co nanowire can reach 31% in weight. The diameter of Tb-Fe-Co nanowire was about 70nm, which was consistent with the pore size of porous anodic alumina template, the length of the Tb-Fe-Co nanowire was from 0.5μm to 2.5μm, crystal structure of Tb-Fe-Co nanowire are Tb2Co17 and FeCo.Magnetic testing of Sm-Co alloy nanowire array film shows that it has obvious perpendicular magnetic anisotropy. Squareness ratio was 0.30, the coercivity was 314Oe. Magnetic testing of Tb-Fe-Co with different Tb content show that perpendicular magnetic anisotropy is not significant when the content of Tb is less than 20 mass %, with the increase of Tb content, both the the coercivity (Hc) and remanent magnetization (Mr) increase, Tb-Fe-Co show obvious perpendicular magnetic anisotropy when the content of Tb greater than 20 mass %.Then the Tb content is fixed at 31 mass%, magnetic testing of Tb-Fe-Co alloy nanowire array film with different deposition time was performed. The result show that perpendicular magnetic anisotropy is not obvious when the deposition time less than 15min, with the increase of deposition time, both the coercivity (Hc) and remanent magnetization (Mr) increased, Tb-Fe-Co show obvious vertical magnetic anisotropy when the deposition time greater than 15min. Tb content is 31 mass%, deposition time is 20min, the rectangular ratio was 0.41, the coercivity was 574Oe. |
PDF Full Text Request