Local structure analysis of CaBaNbO in high-temperature phase

Yoneda, Yasuhiro   ; Fu, D.*

CaBaNbO (CBN) in which Ba of BaNbO is replaced with Ca, which is a ferroelectric substance having a tungsten bronze structure, A single-phase tetragonal phase appears in the composition range where the amount of Ca substitution is 0.19 0.32. For CBN, superlattice reflection appears in the powder X-ray diffraction pattern even in ceramic samples. There is a long-period structure that is deviated from the average structure. Since superlattice reflection is still observed in the high-temperature phase, structural analysis was performed in the high-temperature phase. It was found that the average structure of the high-temperature phase well reflected the local structure of the room temperature phase. It is considered to be a phenomenon that reflects the reentrant phase transition peculiar to tungsten bronze.