Preparation of chromium doped phosphate glass adopting microwave irradiation and comparative analysis of properties with conventional glass

Chromium doped phosphate glass was melted adopting microwave (MW) heating and properties were compared with conventional glass. Standard methods of characterization adopting X-ray diffraction (XRD), density, UV-Vis-NIR absorption spectroscopy, Refractive indices (RI), Fourier Transform Infrared (FT-IR) spectroscopy, X-Ray Photoelectron spectroscopy (XPS), Differential Scanning Calorimetry (DSC) were performed to evaluate the properties of the glasses. XRD analysis confirmed the amorphous nature. Enhanced absorption peaks in UV-Vis spectra at wavelengths 298, 456, 660 and 685 nm suggest higher Cr3+ concentration in MW prepared glass. Alteration in peak intensities and shift in binding energy in XPS confirm the presence of Cr(III) in different coordination and orientation in glass. Spectrophotometric method developing colour complex of Cr[VI] with 1,5-diphenyl carbazide indicates absence of Cr[VI] in the glass. Presence of IR bands due to different phosphate bonds depicts similar structure in both the glasses. Difference in density, RI, and glass transition temperature (Tg) are also observed in MW melted glass. Maximum instantaneous electrical power was 1.4 kW in MW cavity, whereas 4 kW was recorded in resistive heating furnace. Reflected power remains within 15% of forward power. Total melting time was ~ 2 h in MW heating unlike 6-7 h in resistive heating.