ラマン分光分析法による窒化ケイ素HIP焼結体の構造欠陥の評価

概要

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Raman spectroscopy was used to analyze the crystal structure of Hot Isostatically Pressed silicon nitride (Si_3N_4 containing 0.5 mol% of Y_2O_3, 0.5 mol% of Nd_2O_3 and 1 mass% of Si_3N_4 whiskers)to confirm whether microstacking faults occurred in the β-phase due to structural defects in the silicon nitride grains. With this technique, the presence or absence of a 514-520 cm^<-1> peak confirms whether or not such stacking faults have occurred. For the β-phase alone of orientation-controlles silicon nitride, a large grain diameter and high thermal conductivity were obtained. In contrast, for gas-pressure hot-pressed silicon nitride, the grain diameter was smaller and stacking faults occurred in the β-phase, even though the heat treatment process was performed at the same temperature. It was found that structural defects in the crystal grains caused phonon-impurity scattering, resulting in a decline in thermal conductivity. This indicates that structural defects in the grains must be eliminated to obtain high thermal conductivity. The results of this study suggest that Raman spectroscopy can be an effective technique for conducting structural analyses to determine the presence of such defects.
社団法人日本セラミックス協会の論文
1999-04-01