Brasil
| article
XAFS characterization of La1−xSrxMnO3±δ catalysts prepared by Pechini’s method
Registro en:
0301-0104
10.1016/j.chemphys.2005.09.008
Autor
Melo, Dulce Maria de Araújo
Borges, Filipe Martel de Magalhães
Ambrósio, Renato Canha
Pimentel, Patricia Mendonça
Silva Júnior, Carlos Neco da
Melo, Marcus Antônio de Freitas
Resumen
XAFS experiments at the Mn and Sr K-edges were carried out in order to investigate the short-range arrangement of Mn and Sr sites on La1−xSrxMnO3±δ highly doped perovskites (x = 0, 0.2, 0.4 and 0.6). The Mn K-edge EXAFS spectra show a static Jahn–Teller distortion of the MnO6 for x = 0 and 0.2, which is drastically reduced as x increases. The distortion of perovskite, characterized by the Mn–O–Mn tilt angle, progressively decreases with increasing Sr contents. Sr K-edge results indicated a decrease on the Sr–Mn coordination number upon Sr doping. Based on this and TPD results, a charge compensating mechanism is proposed suggesting a partial Mn oxidation and formation of Mn defect vacancies due to the introduction of Sr.