Size effect on multiferroics LuMn2O5 nanorods
| Autor: | Hao-Wei Tu, 塗浩瑋 |
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| Rok vydání: | 2013 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 101 Series of multiferroics LuMn2O5 nanorods were synthesized by hydrothermal method. Different sizes of nanorods were obtained by various annealing temperatures. X-ray diffraction, FE-TEM, and SAED techniques were employed to determine the crystal structure, composition, and purity. The SQUID was used to study magnetic properties. Varied temperature x-ray powder diffraction and Raman spectroscopy were employed to analyze the interplay between structure and magnetic properties. The sizes of nanorods were first determinate by counting the axial and radial lengths in TEM images. The average axial and radial lengths were labeled in the format of length × width. Four sizes of nanorod, 66(22) nm×18(5) nm, 78(38) nm×22(9) nm, 102(44) nm×23(8) nm and 91(35) nm×20(7) nm were thus obtained. High resolution images and SAED patterns indicated that the c-axis is parallel to the axial direction in all samples. In the brief, the axial length of all samples was used to label and write as. The magnetic susceptibility curves can be described by spin-spin and spin-orbit interaction above 80 K for all samples. Relative larger effective magnetic moment that obtained from Curie-Weiss fitting revealing the spin-orbit interaction was not ignorable for all samples. Below 50 K, two antiferromagnetic peaks at around 38 and 45 K were observed as larger than 66 nm. It is found that Néel temperatures increased with increasing. Varied temperatures Raman spectroscopy were used to study the phonon modes of = 78 nm and = 91 nm samples. A fluctuation at around 160 K and 190 K were found in = 78 nm and 91 nm samples. Similar results are also found in the bond length of Mn-O and bond angle of Mn-O-Mn obtained from VT-XRD results. A fluctuation at around 160 K and 190 K for < Lc >=78 and 91 nm are found, respectively. This implies the size effect results distortion of structure, and influenced the magnetic properties of LuMn2O5 nanorods. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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