|About this Abstract
||Materials Science & Technology 2009
||Characterization and Modeling of Ceramic-Ceramic and Metal-Ceramic Interfaces
||Interfaces of Silicon Nitride Ceramics: Direct Imaging and First-Principles Studies
||Weronika Walkosz, Robert F Klie, Serdar Ogut, Biliana Mikijelj, Paul Becher, Albina Borisevich, Stephen Pennycook, Juan C. Idrobo
|On-Site Speaker (Planned)
The widespread use of Si<SUB>3</SUB>N<SUB>4</SUB> in many high temperature and pressure applications is limited by brittleness. Rare-earth (RE) oxides, when included in Si<SUB>3</SUB>N<SUB>4</SUB>, have long been empirically known to overcome this problem by promoting the formation of a reinforced toughened microstructure. Using a combination of atomic-resolution Z-contrast imaging and electron energy-loss spectroscopy (EELS) as well as ab initio calculations, we examine the atomic and electronic structures at the interface between β-Si<SUB>3</SUB>N<SUB>4</SUB> and (i) CeO<SUB>2−δ</SUB> inter-granular film (IGF) as well as (ii) SiO<SUB>2</SUB> IGF. Our results show that O is present at the interface in direct contact with the terminating Si<SUB>3</SUB>N<SUB>4</SUB> structures and that the presence of REs affects the termination of Si<SUB>3</SUB>N<SUB>4</SUB> surface. Moreover, direct imaging of individual atomic columns formed by light elements in Si<SUB>3</SUB>N<SUB>4</SUB> was achieved. The observed structural and electronic variations at these interfaces will be briefly discussed in conjunction with the theoretical results.