A comparative study on copper doped sodium alumina-phosphate glass with conventional and microwave heating

Abstract

Natural distribution of copper ions Cu[I] and Cu[II] in sodium alumina-phosphate glass system under Microwave (MW) heating has been investigated and compared with conventional glass. Higher broad absorption at above 850 nm is observed in glass obtained from resistance heating signifying higher presence of Cu[II] in conventional glass than that obtained from microwave heating as seen from UV–Vis–NIR spectra. Photoluminescence spectra revel complimentary information on higher presence of Cu[I] content in MW prepared glass. The peak centre of Cu-2p3/2 as well as Cu-2p1/2 shifted towards higher binding energy and appeared much broader in conventional glass than the glass obtained from MW heating suggesting higher amount of Cu2+ in conventional glass. Moreover, more weight gain in thermo-gravimetric analysis (TGA) suggests higher retention of Cu[I] in MW melted glass. Raman spectra indicate the P–O non-bridging bond weakening effect upon increasing the copper content; representing the structure modifying role of copper ions on the phosphate network. Fourier Transform Infrared (FT-IR) spectra show the structural features of the phosphate network prepared under two different heating mechanisms. In addition, significant less energy consumption in MW heating makes it energy efficient heating for glass melting.