Impurity Phases in Hot‐Pressed Si ₃ N ₄

Abstract

Impurity phases in commercial hot‐pressed Si 3 N 4 were investigated using transmission electron microscopy. In addition to the dominant, β‐Si 3 N 4 phase, small amounts of Si 2 N 2 O, SiC, and WC were found. Significantly, a continuous grain‐boundary phase was observed in the ∼ 25 high‐angle boundaries examined. This film is ∼ 10 Å thick between, β‐Si 3 N 4 grains and ∼ 30 Å thick between Si 2 N 2 O and β‐Si 3 N 4 grains.