Synthesis and Magnetism of CuMn2-xMgxO4(x=0~0.8) Nanowires

• Main Authors: Po-Chien Cheng, 鄭博謙
• Other Authors: Ming-Der Lan
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/sjf772

碩士 === 國立中興大學 === 奈米科學研究所 === 101 === 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.