Method of distinguishing SrBi2Ta2O9 phase from fluorite phase using X-ray diffraction reciprocal space mapping

In the Sr-Bi-Ta-Nb-O system, three crystallographic phases are known to exi st: the SrBi2(Ta1-xNbx)O-9 (SBTN) perovskite, fluorite and pyrochlore phase s. It is considered that the fluorite phase is a low-temperature phase of S ET, which tends to grow in excess bismuth compositions, and the pyrochlore phase tends to grow in bismuth-deficient compositions. In conventional X-ra y diffraction (XRD) characterization, the SBTN phase shows strong (115) dif fraction around 29 [2 theta deg]. Unfortunately, however, the other two pha ses also show their (111) and (222) diffractions near the same angle when t he film is prepared on a platinum-coated silicon substrate. Therefore, the phase identification of the SBTN phase from the other two phases is almost impossible by the conventional technique. We employed XRD reciprocal space mapping to distinguish these phases in the present study. The three crystal lographic phases were identified and distinguished from each other. It is a scertained that this technique is effective to identify crystallographic ph ases especially in the case in which more than two phases show similar diff raction angles.