Grain Boundary Films in Rare‐Earth‐Glass‐Based Silicon Nitride

Abstract

The thickness of the intergranular films in Si 3 N 4 densified with lanthanide oxides has been systematically investigated using high‐resolution transmission electron microscopy. Four lanthanide oxides—La 2 O 3 , Nd 2 O 3 , Gd 2 O 3 , and Yb2O3—as well as Y 2 O 3 are chosen so that the results will reflect the overall trend in the effect of the lanthanide utilized. The film thicknesses increase with increasing ionic radius of the lanthanide. In addition, Si 3 N 4 particles flocculated into isolated clusters in the lanthanide‐based glasses are also characteristically separated by an amorphous film whose thickness is similar to that in the comparable polycrystalline ceramics, demonstrating that the film thickness is dictated entirely by the composition and not by the amount of the glass phase present.