Research On Magnetic And Luminescence Properties Of La-Ni Seriesalloy Nanotubes (Nanowires)

The rare-earth metals or alloys have attracted more attention, due to their fundamental physical and chemical properties with unique 4f electronic structure. In this paper, La-Ni nanowires/nanotubes and La-Ni:Sm nanowires have been successfully fabricated into nano-pores of the anodic aluminum oxide (AAO) templates by DC electrochemical deposition method. The AAO templates include commercial templates and self-made templates. The crystalline structure and morphology of samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM), and the compositions were confirmed by energy dispersive spectrometry (EDS). The magnetic properties of samples were measured by vibrating sample magnetometer (VSM).The La-Ni nanowires/nanotubes were fabricated into the AAO templates with different pores diameter. XRD and SEAD analysis prove that the crystal structure of the samples is poor. Magnetic measurement shows that La-Ni nanowires/nanotubes arrays have the obvious magnetic anisotropy, and the easy magnetization axis is parallel to the axis of nanowires/nanotubes. This is mainly determined by the shape anisotropy. After annealing under the protection of nitrogen, the magnetic properties of La-Ni alloy nanotubes can be changed. This is mainly determined from shape anisotropy to the magnetostatic interaction, and easy magnetic axis from parallel to the axis of the nanotubes to perpendicular to the axis of the nanotubes, and magnetocrystalline anisotropy is almost the same.The La-Ni:Sm nanowires were fabricated into the AAO templates with different pores diameter. Without doping Sm3+, La-Ni alloy nanowires array appear the phenomenon of luminescence which results from the Ni electronic transition. Doping Sm3+, La-Ni:Sm alloy nanowires appear the peak of Sm3+. The inspire peak is at 342 nm,360 nm,370 nm,408 nm,432 nm,470 nm and 480 nm, respectively corresponding to 6H5/2�'4K17/2、6H5/2�'4D3/2、6H5/2�'6P7/2、6H5/2�'4K11/2、6H5/2 �'4M19/2 and 6H5/2�'4I13/2 transition; Emission peak at 572 nm,603 nm and 643 nm, corresponding to 4G5/2�'6H5/2、4G5/2�'6H7/2、4G5/2�'6H9/2 transition. The fluorescence intensity is biggest when the ratio of La-Ni:Sm alloy nanowire arrays is 3:100. Doping the same Sm3+, the fluorescence intensity of La-Ni:Sm alloy nanowire arrays first increases then decreases with the temperature increasing. Fluorescence intensity is the largest when T=400 ℃. The fluorescence intensity of La-Ni:Sm alloy nanowire arrays first increases then decreases with increase of the diameter, and the fluorescence intensity arrive at maximum when D=100 nm.