National Changhua University of Education Institutional Repository : Item 987654321/14250
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题名: The Effects of Sintering Temperature on Preparation, Resistivity, and Thermopower of c-axis Oriented Ca3Co3.95Fe0.05O9+δ Films fabricated Using Sol-gel spin Coating Method
作者: Liu, Chia-Jyi;Nayak, Pradipta K.;Lin, Zhi-Ru;Jeng, Kai-Yi
贡献者: 物理學系
关键词: Thermoelectrics;Cobaltites;Sintering temperature;Barrier theory;X-ray diffraction;Atomic force microscopy;Electrical measurements and properties
日期: 2008-10
上传时间: 2012-09-10T06:15:41Z
出版者: Elsevier
摘要: We report fabrication of the c-axis oriented Ca3Co3.95Fe0.05O9 + δ films by a simple sol–gel spin coating method. The films prepared in the temperature range of 650–700 °C show nonmetallic temperature dependence of resistivity in the whole investigated temperature range, whereas the films prepared in the temperature range of 750–775 °C show metallic temperature dependence in the high temperature regime. Sintering the films at higher temperature leads to larger grains, lower resistivity and smaller thermoelectric power. This can be explained in the framework of the barrier theory and confirmed by the higher hole carrier concentration from the Hall measurements according to Seto's derivation between the carrier concentration and the barrier height. The temperature dependence of resistivity resembles that of the in-plane single crystal of Ca3Co4O9 + δ in terms of the Fermi-liquid behavior. The effects of lower sintering temperature on the transport coefficient A and Fermi-liquid scale T⁎ of Fe-substituted cobaltite films seems to be similar to applying hydrostatic pressure on a single crystal of Ca3Co4O9 + δ. The temperature dependence of resistivity in the nonmetallic region follows the variable-range hopping conduction in the form of T− 1/3, due to the 2-dimensional character of the films.
關聯: Thin Solid Films, 516(23): 8564-8568
显示于类别:[物理學系] 期刊論文

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