Study of La1−xMnO3−δnon-stoichiometry and defect structure using ESR and iodometry

✍ Scribed by M. Ippommatsu; S. Otoshi; H. Sasaki; H. Ohnishi; T. Higuchi; M. Miyayama; H. Yanagida

• Publisher: Springer
• Year: 1993
• Tongue: English
• Weight: 295 KB
• Volume: 28
• Category: Article
• ISSN: 0022-2461
• DOI: 10.1007/bf00414259

✦ Synopsis

The oxidation states of manganese in the Lal_xMnO3_~ (x--0.09-0.11) were investigated by electron spin resonance (ESR) and iodometry. The ESR analysis carried out at room temperature for the samples prepared in air revealed the presence of broad peaks at g = 2.0, considered to be relevant to Mn 2 § It was also found that the intensity of the peak increased as lanthanum vacancy content increased. The average valence state of manganese, determined by iodometry, was approximately 3.2, and decreased by 1 as the lanthanum vacancy increased by 1. Similar trends were observed with the samples prepared at Po~ = 1 • -7 atm. The results indicated that Mn 2 § is stably present in the La~_xMn03_~ having an average valence number exceeding 3.0. A series of experimental results with respect to the non-stoichiometry of La~ _,Mn03_~ can be explained by assuming that Mn 2+ is stabilized after forming a complex with a lanthanum vacancy and two oxygen vacancies.