Topotactic migration of cationic vacancies in La_(1-t)Mn _(1-t)O_3

摘要

A reversible topotactic oxidizing-reducing process has been clearly evidenced in the annealing treatment followed to stabilize rhombohedral and orthorhombic La_(1-f)Mn_(1-f)O_3 (0.016 ≤≤ 0.038) samples. The study of the surface evolution followed by characterization by scanning electron microscopy (SEM) and atomic force microscopy (AFM) gives evidence for a diffusion mechanism of La and Mn cations through the grain boundaries which provides a fast pathway in the perovskite related compound; however, contrary to theoretical predictions, the overall cationic ratio (La:Mn 1:1) is kept.