An X-Ray Diffraction and Thermogravimetric Study of Layered Perovskite Y1−xBixBaCo4O7

Layer-structured oxides Y1−xBixBaCo4O7 (0.00 ≤ x ≤ 0.05) were successfully synthesized and their structural and oxygen absorption properties were investigated by x-ray diffraction and thermogravimetry. Though Bi solubility was limited to about 5%, corresponding to Y0.95Bi0.05BaCo4O7, it is found that the structure and oxygen absorption properties of Y1−xBixBaCo4O7 are affected significantly as the Bi content x increases. Rietveld refinement results show that Y1−xBixBaCo4O7 (x ≤ 0.05) is single phase with a hexagonal crystal structure (space group P63zmc). Unit cell parameters and volume are changed and CoO4 tetrahedra are distorted along the c-axis in Bi doped YBaCo4O7. The TG results show that Y1−xBixBaCo4O7 undergoes two oxygen absorption processes in oxygen from room temperature to 1000°C and the maximum mass increase of the doped samples is less than that of YBaCo4O7. Bi doping effects on the structure and oxygen absorption properties are discussed on the basis of average radius and disorder of the Y site, the valence of Bi and the oxygen activation energy. (cross-disciplinary physics and related areas of science and technology)