Rare-earth adsorption at intergranular interfaces in silicon nitride ceramics: Subnanometer observations and theory
Shibata, N; Painter, GS; Satet, RL; Hoffmann, MJ; Pennycook, SJ; Becher, PF
PHYSICAL REVIEW B, 2005, Band 72, Heft 14
Rare-earth adsorption at intergranular interfaces in silicon nitride ceramics: Subnanometer observations and theory.
It is shown that the rare earths (REs) have different tendencies to segregate to the grain surfaces in silicon nitride ceramics, and this alters the filling of adsorption sites on the prismatic plane surfaces. Here, the adsorption and binding strengths of RE segregants at prismatic grain surfaces are determined by first-principles calculations. The adsorption of three rare earths (La, Gd, and Lu) is expected to be distinctly different at the predicted adsorption sites, and this is confirmed by atomic-resolution scanning transmission electron microscopy images. This combination of theory and experiment provides a basis for understanding the adsorption behavior of RE elements in silicon nitride ceramics.