Development of hydrogen reduction method for La-Fe-Si materials from oxalate precursors

Abstract

Hydrogen reduction was used to synthesise LaFeSi-based materials from lanthanum, cerium, iron oxalates, and silicon dioxide. The process involved the pre-reduction of the precursor powder mixture at 650 & DEG;C under N-2 for 1 h, followed by a full reduction under H-2 for 2 h at 900 & DEG;C. The predominant phases in the synthesised materials were a-Fe, lanthanum, cerium, and silicon oxides. A decrease in the La/Ce ratio in the main composition resulted in an increase in the a-Fe phase. The rest of the non-oxidized materials showed an Fm-3 m structure. Both XRD and EDS analyses indicated the presence of metal/oxide composite structure in the synthesised materials. The oxide morphology observed in SEM images exhibited a porous media. The room temperature VSM analysis showed that x = 0.3 product had the highest coercivity as 26 Oe and the lowest saturation magnetisation as 106.3 emu/g.