Abstract
A comparison is made between the local distortions at room temperature of the octahedra in three perovskite families in which M is Mn, Fe, or Ni. The comparison distinguishes between distortions arising from cooperative octahedral-site rotation and static Jahn-Teller (JT) distortions. The and ions have localized electrons with primarily ionic M-O bonds whereas the Ni-O bond lengths reflect the crossover from insulator to metallic behavior. Below a critical Ni-O-Ni bond angle, stabilization of two distinguishable sites is more compatible with the segregation into primarily ionic bonding at a JT distorted octahedral site and primarily covalent Ni(III)-O bonding at a less distorted site of smaller mean Ni-O bond length rather than charge transfer between the two Ni sites. Moreover, below a smaller critical bond angle, which is the same in all three families, the domination of the interaction weakens relative to next-nearest-neighbor interactions.
- Received 20 October 2003
DOI:https://doi.org/10.1103/PhysRevB.69.153105
©2004 American Physical Society