Alumina Nanopores Template-Assisted Growth of γ-Na0.7CoO2 Thermoelectric Nanotubes and Effects of Li Doping on the Thermoelectric Properties of γ-Na0.7CoO2

• Main Author: 陳叔佑
• Other Authors: 劉嘉吉
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/79073219865602878134

碩士 === 國立彰化師範大學 === 光電科技研究所 === 96 === Abstract Because of its high thermopower and low resistivity properties, Sodium Cobalt Oxide system has been studied extensively. The results of theoretical calculation show that nanowire structures have the potential to significantly improve the thermoelectric figure of merit. Recent work in thermoelectric nanowire has attracted a great deal of research interest because of their potential application in thermoelectric devices. In this study, we use aluminum foil ( 99.9995% of purity ) as substrate to fabricate periodic nanopore arrangement in porous alumina template using an anodic oxidation method. The pore array of the film has a uniform, closely packed honeycomb structure. By controlling the potential and time of expanding pores,we get two kinds of size of diameter approximately 50 nm γ-Na0.7CoO2 nanowire arrays were grown in highly ordered nano -channel of an alumina template using vacuum immersion.Immersion solution was prepared by Sol-gel deposition containing NaNO3 and Co(NO3)2 and urea. Calcined the substrate at 650 ℃ and 6 hours. And subsequent the etching step to remove AAO. Not only patterns of XRD, but morphology and nanostructure were observed by SEM and TEM. EDS analysis indicates that the atomic composition of Na and Co is very close to a 0.7:1 stoichiometry.