Silicoaluminate magnetic polychromatic glasses: Thermal, optic and magnetic properties

Abstract

The magnetic state associated with new brown and green aluminosilicate glass systems has been identified. The samples were prepared by the conventional melting method, followed by rapid cooling, using a mineral residue. X-ray diffraction (XRD) results, corroborated by images obtained through scanning electron microscopy (SEM), confirmed the formation of the amorphous phase. Differential scanning calorimetry (DSC) analysis showed high glass transition ($800-860°C$) and crystallization ($1160-1180°C$) temperatures, contributing to good thermal stability of the glasses. UV–Vis spectrophotometry results showed the presence of absorption and transmittance bands, with good absorbance in the ultraviolet region and transmittance in the visible light region with wavelengths between 350–800 nm. The band gap values were observed to vary from $1.06\text{eV}$ to $1.82\text{eV}$, indicating a correlation with the oxidation states of iron. Magnetic property studies were conducted through hysteresis curves obtained at 300K, using a vibrating sample magnetometer (VSM), where ferromagnetic and antiferromagnetic contributions resulting from an asperomagnetic regime of the glasses were observed. Electron paramagnetic resonance (EPR) spectroscopy results identified the spectra of Fe³⁺ incorporated into the aluminosilicate glass. The diverse characteristics of these glasses enable their applications ranging from flat panels for civil construction, optical fibers, magnetic devices, to ultraviolet radiation filters.