Studies on electrode thin film materials for thermo-electric generation system

点击翻译按钮获取中文摘要

Fabrication and electric properties of TiBィイD22ィエD2 thin films : A titanium diboride has been well known to heat-resistant ceramics with relatively high electric conductivity. In the present study, we have investigated the electric properties of TiBィイD22ィエD2 thin films as one of potential candidates for electrode materials used at ultra high temperature. TiBィイD22ィエD2 thin films were prepared by RF-sputtering on glass substrates by using stoichiometric and non-stoichiometric TiBィイD22ィエD2 sintered targets. The films were mainly composed of TiBィイD22ィエD2 small crystallites, with a small amount of B-rich amorphous as a second phase. The resistivity of the typical sample was revealed to be about 180 mΩ・cm at room temperature, which was higher than bulk value (33 mΩ・cm). The temperature dependence of the resisitivities seems to be carrier concentration dependent. However, the very high carrier densities (1.2〜6.1 x 10ィイD122ィエD1/cmィイD1-3ィエD1) and the relatively small mobilities (0.3〜2.3 cmィイD12ィエD1・VィイD1-1ィエD1・sィイD1-1ィエD1) were obtained, suggesting that the conduction carrier might behave like nearly free electrons.Fabrication and electric properties of LaCoOィイD23ィエD2 thin films by ion-beam sputtering and subsequent heat treatment. The compacts consisting of LaィイD22ィエD2OィイD23ィエD2 and CoO powder were used for the targets. The films were composed of the almost single phase of LaCoOィイD23ィエD2 with a very small amount of the unidentified second phase. The resistivity at room temperature for the annealed La/Co=1/1 sample was determined to be 51 Ω・m. Whereas at the high temperature, the resistivity was found to be same order of the resistivity for bulk LaCoOィイD23ィエD2, that is, comparable to the resistivity for metals. The temperature dependence of the electric conduction of the samples also behaves like bulk LaCoOィイD23ィエD2, which means the metal-insulator transition is supposed to be realized in thin film samples.