High-resolution transmission electron microscopy and computer simulation of defect structures in electronic perovskite ceramics

Defect chemistry of electronic perovskite ceramics was quite advanced by recent studies using high-resolution transmission electron microscopy (TEM) and computer simulation techniques. Selective site occupation of alkali-earth metal, Ca at Ruddlesden-Popper (RP) faults, causing a break of conduction pathway within a framework of corner-sharing TiO6 octahedra and improved leakage current properties, were unquestionable clarified in A-site-excess SrTiO3. Existence of meta-stable RP faults in BaTiO3 processed under thermodynamically non-equilibrium condition was first empirically and then theoretically proved. Crystallographic shear (CS) structure TiO2 double layer and BaO double layer were first observed and precisely characterized in perovskite ceramics. The obtained new information about defect structure can trigger new ideas about standing reliability issues and should open a challenge in atomic design, based upon computer structural energy calculation in electronic perovskite materials.