Magnetic and structural behaviour of the sol-gel-derived iron aluminosilicate glass-ceramics

The 0.10Fe2O3-0.90 (0.90SiO2·0.10Al2O3) gel-derived glass-ceramic heat-treated at 250, 500 and 1000 °C was studied by means of X-ray diffraction, electron microscopy, IR spectroscopy and magnetic susceptibility measurements. The X-ray diffraction patterns point out that the crystalline phases observed in the studied samples were goethite (α-FeO(OH)) and hematite (α-Fe2O3). The crystalline phase grows with increasing heat-treatment temperatures. The IR data and electron micrographs show that heat treatment determines modifications of the internal network structure of the studied samples. The magnetic susceptibility data indicate an antiferromagnetic behaviour of the samples and the conversion of Fe2+ into Fe3+ ions with increasing heat-treatment temperature.