| Summary: | 碩士 === 國立東華大學 === 應用物理研究所 === 94 === In this study one-dimensional (1D) tungsten trioxide (WO3) nanorods were synthesized on Si wafers without catalyst using a hot-filament thermal evaporation. The 1D WO3 nanorods were synthesizd at an optimal experimental condition that the tungsten is heated at 1500 ℃, the vacuum chamber is 100 torr of argon atmosphere, and the deposition time is 10 minutes. Using Raman spectroscopy, x-ray diffractometry (XRD), and selected area electron diffractometry (SAED), the 1D WO3 nanorods are determined as a cubic crystal in space group Pm3m with lattice constants a = b = c = 3.72 Å。In addition, according to the variable temperature XRD spectra, a diffraction peak of 23.64∘appears at 145 K, indicating that a short range ordering structure is generated.
From the M-H hysteresis loop of the 1D WO3 nanorod, we find the 1D WO3 nanorod is a typical diamagnetic oxide materials, and its diamagnetic susceptibility is independent of temperature. By using Langevin statistical equation, the saturated magnetic moment of the 1D nanorod is simulated at 1.98x10-1 emu/g, its mB and diamagnetic susceptibility are 40 and -2.6x10-4, respectively. The total weight of the synthesized 1D WO3 nanorods is about 1x10-4 g. Because the outmost shell of WO3 is fill-filled, electron current emitted from the 1D WO3 nanorods need large applied electric field, indicating that the 1D WO3 nanorods is not suitable for electrical emitter.
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