Electrical resistivity of Si <sub>3</sub> N <sub>4</sub> ceramics with Yb <sub>2</sub> O <sub>3</sub> additive
Tsukaho Yahagi, Daisuke Kawai, Takuma Takahashi, Motoyuki Iijima, Junichi Tatami
Abstract
Abstract Si 3 N 4 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 Si 3 N 4 ceramics. In this study, the electrical resistivity of Si 3 N 4 ceramics with Yb 2 O 3 additive was investigated by applying various voltages at temperatures ranging from 25°C to 300°C. When Yb 2 O 3 was added as a sintering aid to Si 3 N 4 ceramics, a crystalline J‐phase (Yb 4 Si 2 O 7 N 2 ) was formed and their electrical resistivity was significantly lower than that of Y 2 O 3 additive. The electrical resistivity of the Yb 2 O 3 ‐added ceramics decreased with an increase in temperature and applied voltage. Yb existed in multiple valence states, Yb 2+ and Yb 3+ , in the Si 3 N 4 ceramics and the decrease in the electrical resistivity can be attributed hopping conduction through the J‐phase. The J‐phase in the Si 3 N 4 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 Yb 2 O 3 ‐added Si 3 N 4 ceramics was found mainly to result from the formation of an infinite cluster of J‐phase, which exhibits hopping conduction.