Determination of the Mn3+/Mn4+ ratio in La1-xSrxMnO3 +/- d powders

作者：Siqueira Guilherme Oliveira; Belardi Rose Marie; Almeida Pedro Hespanha; da Silva Charles Luis; Brant Marcia Caldeira; Matencio Tulio; Domingues Rosana Zacarias^*

来源：Journal of Alloys and Compounds, 2012, 521: 50-54.

DOI：10.1016/j.jallcom.2012.01.023

• Electrode materials
• Chemical synthesis
• Powder metallurgy
• X-ray diffraction
• Electronic transport

The present work combines the results of two simple methods of determination of the Mn3+/Mn4+ ratio for La1-xSrxMnO3 +/- d powders, prepared by citrate route, in which the Sr content, x, varies from 0.16 to 0.40. The ratio Mn3+/Mn4+ was successfully estimated combining the results of Temperature Programmed Reduction (TPR) analysis and redox titration. Moreover, the possible perovskite chemical formulas were established and a direct relationship between the Sr content and the Mn4+ amount was found. Morphological analyses such as grain size and surface area are also presented to better characterize the powders. Gas adsorption by Brunauer-Emmett-Teller method (BET) and scanning electron microscopy (SEM) were used to evaluate the agglomeration degree of powders and showed the inhibitory influence of Sr content on the growth of crystallites.

• 出版日期2012-4-25