Abstract
The crystal structure of at high temperatures has been studied using powder neutron diffraction and the Rietveld method. It was determined that from 300 K to approximately 820 K the structure of is orthorhombic The material then undergoes a phase transition and becomes tetragonal between ∼820 and 920 K. The high-temperature (>920 K) structure was found to be the standard cubic perovskite From the neutron-diffraction data and the space group assignments, the orthorhombic to tetragonal phase transition must be first order, while the transition from the tetragonal to cubic phase is consistent with a second-order phase transition.
- Received 1 December 1997
DOI:https://doi.org/10.1103/PhysRevB.58.653
©1998 American Physical Society