Peculiar Five-fold Coordinated Sites Observed in the Oxides with Derivative Structure

摘要

In the oxides with derivative structure of perovskite,peculier five-fold coordinated sites occur at the boundary regionsbetween the fundamental structure units. The five-fold coordinatedtrigonal bipyramidal sites with large distortion have the muchlonger mean bond distances than those expected from the effectiveionic radius and the distances are similar to those of octahedral site.The bond valence calculation for those sites yields significantlower-valences than the expected values due to the longer bond distances.