Observation of octahedral tilted in Sr0.5TaO3 prepared by nanosheet processing: An EXAFS study

The metastable crystal structure of Sr0.5TaO3 with pseudo-cubic structure was investigated by X-ray diffraction analyses and extended X-ray absorption fine structure. Sr0.5TaO3 powders were synthesized from the host material of H2Sr1.5Ta3O10 by direct dehydration and nanosheet processing. The structure of Sr0.5TaO3 is suggested based on X-ray diffraction analyses, while the local structural analyses by extended X-ray absorption fine structure clearly reveals a tilted of TaO6 octahedra in Sr0.5TaO3. It is indicated that planar defects resulting from stacking faults in nanosheet-derived H2Sr1.5Ta3O10 are possibly the cause of the larger tilted of TaO6 octahedra in Sr0.5TaO3 (Ta-O-Ta bond angle (164 deg.)) prepared by nanosheet processing compared with Sr0.5TaO3 (Ta-O-Ta bond angle (169 deg.)) obtained by direct dehydration.