Synthesis of Sr-doped LaMnO3 and LaCrO3 powders by combustion method: structural characterization and thermodynamic evaluation

Cerâmica

A. L. A. Da Silva¹  L. Da Conceição¹  A. M. Rocco¹  M. M. V. M. Souza¹ 

[1] ,Universidade Federal do Rio de Janeiro Escola de Química Rio de Janeiro RJ ,Brazil

关键词: perovskites;    combustion synthesis;    X-ray diffraction;    thermogravimetric analysis;    microstructure;    perovskitas;    síntese de combustão;    difração de raios X;    análise termogravimétrica;   

DOI  :  10.1590/S0366-69132012000400018

来源: SciELO

【 摘 要 】

Lanthanum strontium manganite (LSM) and chromite (LSC) powders, as well as the corresponding non-doped samples, were synthesized by the combustion method, using two different fuels (urea and glycine). The ignition of the reagent mixture with urea takes a longer time and the maximum temperature is higher than using glycine, for doped samples. The theoretical calculations of exothermic heat and adiabatic flame temperatures indicate favorable conditions for combustion to occur. However, calcination is an essential step for a good crystallization of perovskite phase. X-ray diffraction patterns showed formation of only perovskite phase for the samples synthesized with urea. The crystallite sizes are in the range of 19-25 nm, with smaller values when urea was used as fuel. Scanning electron microscopy showed the presence of agglomerates, formed by fine particles of different shapes. Thermogravimetric analysis revealed that the weight loss is much higher for manganites, with complete burn out of organics at 850-900 ºC.

【 授权许可】

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