Physical and optical properties of calcium sulfate ultra-phosphate glass-doped Er2O3

Abstract

The influence of erbium on physical and optical properties of calcium sulfate ultra-phosphate glass was investigated using conventional melt quench process. Selected samples of composition 20CaSO4 (80 – x) P2O5– xEr2O3 with 0.1 [Formula: see text]x [Formula: see text] 0.9 mol.% were prepared and assessed. X-ray diffraction (XRD) techniques were used to confirm the amorphous nature of the said samples. The structural units of phosphate-based glass were assessed from Raman spectra as ultra-(Q3), meta-(Q2), pyro-(Q1) and orthophosphate (Q0) units. Depolymerization process of the glasses was testified for higher calcium oxide content and UV-visible for optical measurement. Thermal analysis have been investigated by means of thermogravimetric analysis. The results show the decomposition of materials in the temperature range of 25[Formula: see text]C–1000[Formula: see text]C. Er[Formula: see text] absorption spectra were measured in the range of 400–1800[Formula: see text]nm. PL measurement was carried out in order to obtain the excitation and emission spectra of the samples. The emission spectra excited at 779[Formula: see text]nm comprises of 518[Formula: see text]nm, 550[Formula: see text]nm and 649[Formula: see text]nm of transition 4F[Formula: see text], 4S[Formula: see text] and 2H[Formula: see text] excited states to 4I[Formula: see text] ground state. In physical properties, the density calculated using Archimedes method is inversely proportional to molar volume with increase in Er[Formula: see text] ions. Optical bandgap (E[Formula: see text]) were determined using Tauc’s plots for direct transitions where E[Formula: see text] (direct) decreases with increase in erbium content. The refractive index increases with decreasing molar volume; this may have a tendency for larger optical bandgap. The result obtained from the glass matrix indicates that erbium oxide-doped calcium sulfate ultra-phosphate may give important information for wider development of functional glasses.