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• Sol-gel synthesized and heat-treated 40Fe x AlSi samples with ' x' of 10, 15, and 20 resulted in the precipitation of fayalite, hematite and maghemite NPs with photocatalytic properties. • The corresponding degradation rate constant k , following the first-order reaction kinetics, was 14.89 × 10−2 min−1 for 40Fe 2 O 3 -15Al 2 O 3 -45SiO 2 sample. • The presence of various crystalline phases that contain iron ions in mixed-valence states favors the formation of continuous pathways for uninterrupted polaronic transport which enhances an increase in DC conductivity. • Electrical conductivity and photocatalytic activity of the composites increase with the alumina content. The glass samples with the composition of 40Fe 2 O 3 - x Al 2 O 3 -(60− x)SiO 2 were prepared by sol-gel method. The samples were characterized by XRD, 80 K 57Fe Mössbauer spectroscopy, TEM, FTIR and impedance spectroscopy. In the glass samples with less than 10% alumina, fayalite and hematite were crystallized by addition of hercynite. Whereas nanoparticles of hematite (α-Fe 2 O 3) and maghemite (γ-Fe 2 O 3) doped with Al were confirmed with the increase of alumina contents (15% and 20%). The glass samples exhibit the electronic conduction which is explained by the polaronic conduction mechanism. It is noticed that the catalysts containing a mixture of hematite and maghemite nanoparticles showed higher photocatalytic degradation of Rhodamine B dye than those containing hematite alone. It is suggested from the characterizations of newly developed iron-containing aluminosilicate glass samples that the materials with several bandgaps and without dissolving itself should be developed in the future for water purification under visible light irradiation. [ABSTRACT FROM AUTHOR]