Influence of Firing Temperatures on Phase Formation and Microstructure of La_0.92Mg_0.18Fe_0.90O₃ Ceramics Synthesized via the Combustion Route

Abstract

A novel combustion technique has been developed to synthesize La_0.92Mg_0.18Fe_0.90O₃ or LMF ceramics. The NH₂CH₂COOH was used as the fuel to accelerate the chemical reaction of raw materials. Thermogravimetric TG and differential thermal analysis DTA were used to estimate the calcination temperature in the range from 800 to 1000°C. The pure perovskite phase was obtained for the samples calcined at 900°C for 2 h. This calcination temperature was selected for the pellets sintered between 1000°C and 1200°C for 2 h. The effect of calcination and sintering temperatures on the phase and morphology evolution of perovskite LMF was investigated. The XRD patterns indicated that LMF exhibited orthorhombic perovskite structure. With increasing the firing temperatures, the lattice parameters and the unit cell volume changed only slightly; the average particle size and the average grain size tended to increase from 133 to 227 nm and 0.40 to 0.92 μm, respectively. The density of sintered ceramics changed between 3.19 and 3.37 g/cm³ depending on the sintering temperature.

Keywords:

• Lanthanum magnesium iron
• combustion route
• perovskite structure
• gas sensing

Acknowledgments

This work was financially supported by the Thailand Research Fund (TRF) and Commission on Higher Education (CHE). Thanks also to Department of Physics, Faculty of Science, Naresuan University for supporting facilities. Acknowledgments also to Prof. Dr. Galina Popovici for helpful comments and corrections of the manuscript.