| Affiliation: | 1. Kawasaki Technical Support Department, Kanagawa Institute of Industrial Science and Technology, Kawasaki, Kanagawa, Japan
Graduate School of Engineering Science, Yokohama National University, Yokohama, Kanagawa, Japan;2. Graduate School of Environment and Information Sciences, Yokohama National University, Yokohama, Kanagawa, Japan;3. Mechanical and Materials Engineering Department, Kanagawa Institute of Industrial Science and Technology, Ebina, Kanagawa, Japan;4. Faculty of Environment and Information Sciences, Yokohama National University, Yokohama, Kanagawa, Japan |
| Abstract: | Si3N4 ceramics with excellent mechanical properties are used for heat dissipation substrates and so on. In order to improve their reliability and expand their application fields, it is desirable to understand and control the electrical properties of Si3N4 ceramics. In this study, the electrical resistivity of Si3N4 ceramics with Yb2O3 additive was investigated by applying various voltages at temperatures ranging from 25°C to 300°C. When Yb2O3 was added as a sintering aid to Si3N4 ceramics, a crystalline J-phase (Yb4Si2O7N2) was formed and their electrical resistivity was significantly lower than that of Y2O3 additive. The electrical resistivity of the Yb2O3-added ceramics decreased with an increase in temperature and applied voltage. Yb existed in multiple valence states, Yb2+ and Yb3+, in the Si3N4 ceramics and the decrease in the electrical resistivity can be attributed hopping conduction through the J-phase. The J-phase in the Si3N4 ceramics was observed to be continuous, and percolation analysis suggested that the J-phase formed an infinite cluster. Therefore, the decrease in the electrical resistivity of the Yb2O3-added Si3N4 ceramics was found mainly to result from the formation of an infinite cluster of J-phase, which exhibits hopping conduction. |
