Resumo

LIRA HERNANDEZ, I. A.; BOLARIN MIRO, A. M.; SANCHEZ DE JESUS, F.  e  CORTES ESCOBEDO, C. A.. Estabilidad térmica de manganitas tipo La_1-xCa_xMnO₃ obtenidas mediante mecanosíntesis. Superf. vacío [online]. 2009, vol.22, n.3, pp.49-56. ISSN 1665-3521.

In this work is evaluate the thermal stability of manganites of lanthanum doped with calcium of type La_1-xCa_xMnO₃. The synthesis was carried out using of mechanical milling of energy high were mixed in stoichiometric proportions of metallic oxides, La₂O₃3, CaO y Mn₂O₃ as precursors varied x from 0 to 1 in increments of 0.1. The equipment employ was a SPEX 8000D mixer/mill, realize during milling different interlude of time at room temperature, at an oxide atmosphere and using an relation in weight of balls to powder of 10:1. We use thermogravimetric analysis, TGA/DTA and differential scanning calorimetry DSC, for determine the compositions with major thermal stability, in function of milling time and doped level. The results obtained allowed establish the produced reaction during the thermal treatment. They were identified process of oxidation-reducction during the heating of the ceramics as well as structural changes when increasing the milling time for the composition fixed, is low the temperature necessary for propitiate the formation of the manganite with structure orthorrombic, attributable to major increase of energy during the process of milling. The results indicate that the compositions more stables are those with level doped (x) beetwen 0.4 y 0.5, Should due to what possess a factor of tolerance more near to 1 and therefore major thermal stability.

Palavras-chave : Lanthanum Manganite; Mechanosynthesis; Thermal Stability; Crystal Structure; Activation Energy.

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