CuMn2-xMgxO4(x=0~0.8)奈米線的製備及其磁性的研究

Abstract

In our investigation, we use the sol-gel method in coordination with anodic aluminum oxide (AAO) as a substrate to prepare nanowire arrays of CuMn2-xMgxO4(x=0、0.2、0.5、0.8). First, we observe the morphology of nanowries via field emission scanning electron microscope (FE-SEM) and high resolution transmission electron microscope (HR-TEM). The nanowires' diameter is about 65±5nm, and their length is about 44μm. Second, we use selected area diffraction and X-ray powder diffraction to study the crystal structure and lattice constants. Both bulks and nanowires of CuMn2-xMgxO4(x=0、0.2、0.5、0.8) are ferromagnetism. The speculation of the reduction of Curie temperature for nanowires is due to finite-size effects. The scaling theory ξ(T)=ξ_0 [1-T/(T_C (∞) )]^(-ν)proposed by Fisher et al. was used to describe the finite-size effects in the critical region. With the increasing Mg2+ concentration, the couplings among Mn3+/ Mn4+ ions decrease that results in the decrease of Curie temperature and spin correlation length.