Topotactic Migration of Cationic Vacancies in La 1– t Mn 1– t O 3

A reversible topotactic oxidizing-reducing process has been clearly evidenced in the annealing treatment followed to stabilize rhombohedral and orthorhombic La 1-t mn 1-t O 3 (0.016 ≤ t ≤ 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.