Enhanced nitridation of silicon compacts by Yb2O3 addition

The catalytic effect of ytterbium oxide (Yb2O3) on the nitriding reaction of Si compacts was investigated. Si powder mixtures containing Yb2O3 were prepared and nitrided in the form of compacts with a multi-step heating schedule over the range of 1200 °C-1450 °C. The nitriding profiles of the powder mixture with increasing temperature indicated that Yb2O3 clearly promoted the nitridation of Si compacts at 1200 °C compared with the pure Si compact containing no additives. The critical role of Yb2O3 on the nitridation of Si, was elucidated that Yb2O3 promotes the loss of initial SiO2 of the raw Si powder via the measurement of the weight changes at low temperature (1100 °C) and thermogravimetric analysis under N2 atmosphere. It was also found that the β-ratio of fully nitrided Si was closely related to the intermediate degree of nitridation at 1200 °C and 1300 °C.