Mössbauer Characteristics of the Nonstoichiometric Sr2LaFe3O8+δ Perovskite Obtained by Electrochemical Oxidation

Alain Wattiaux (1) , Léopold Fournès (1) , F. Zhou (1) , Jean-Claude Grenier (1) , Michel Pouchard (1) , Jean Etourneau (1)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux

The nonstoichiometry and the vacancy ordering in the perovskite Ca2LaFe3O8 has been investigated in previous works [1,2]. More recently, the occurrence of a large nonstoichiometric domain has been shown in the Sr2LaFe3O8+δ system [3]. Thus, we have used a new "Chimie Douce" method : electrochemical oxidation which has been developped in our laboratory [4] for obtaining Sr2LaFe3O8.90 in alkaline medium. The starting material Sr2LaFe3O8 has been characterized by XRD, chemical analysis and Mössbauer spectroscopy. This compound contains only Fe3+. The Mössbauer spectroscopy reveals, in the oxidized phase, the occurrence of antiferromagnetic interaction below TN = 195 K with a good agreement with electric and magnetic measurements. At low temperature, the presence of two sextets can be explained in terms of a charge disproportionation : 2 Fe 4+ → Fe(4-λ)+ + Fe(4+λ)+ .

Mots clés: Perovskite; Nonstoichiometric; Mössbauer spectroscopy; Oxidation; Electrochemistry

Domaines: Articles anciens

Alain Wattiaux, Léopold Fournès, F. Zhou, Jean-Claude Grenier, Michel Pouchard, et al.. Mössbauer Characteristics of the Nonstoichiometric Sr2LaFe3O8+δ Perovskite Obtained by Electrochemical Oxidation. Journal de Physique IV Proceedings, 1997, 07 (C1), pp.C1-351-C1-352. ⟨10.1051/jp4:19971142⟩. ⟨jpa-00254786⟩