Structural and optical properties of undoped and manganese doped calcium zinc borophosphate glasses

Abstract

Five series of glasses with the chemical compositions xB2O3–(50–x)P2O5– 20CaO–30ZnO, (0 = x = 50 mol%), xZnO–(50–x)CaO–20B2O3–30P2O5, (0 = x = 50 mol%), 20B2O3–30P2O5–20CaO–30ZnO–xMnO2, (0 = x = 10 mol%), xB2O3–(50– x)P2O5–19CaO–30ZnO–1MnO2, (0 = x = 50 mol%) and xZnO–(30–x)CaO–35B2O3– 34P2O5–1MnO2, (0 = x = 30 mol%) were prepared using conventional melt quenching technique following by annealing process. The structure of the glasses were characterized using X–ray diffraction (XRD), Fourier transform infrared (FT– IR) and Raman spectroscopy. XRD analysis confirmed amorphous phase of the glass samples. The IR spectra reveal the coexistence of BO3, BO4, PO3 and PO4 structural units in the glass samples. While the Raman spectra reveals the presence of P–O–B network in the glass samples. The optical properties of the glass samples were characterized using ultraviolet visible near infrared (UV–Vis–NIR) spectroscopy and photoluminescence spectroscopy. The UV–Vis–NIR spectra reveal the presence of both Mn2+ and Mn3+ ions when manganese was doped in borophosphate glasses. Meanwhile, the emission spectra of borophosphate glasses exhibited a green light emission due to tetrahedral symmetry and a red light emission due to octahedral symmetry. The decay curves of 4T1g energy level of Mn ions were examined for all concentrations and the measured lifetimes were dependent on concentration of Mn ions and composition of the glass. The paramagnetic properties were studied using electron spin resonance (ESR) spectroscopy. The ESR spectra reveal that the resonance peak occurring at geff ˜ 2.0, 3.3 and 4.3. The resonance peak at geff ˜ 2.0 with six lines hyperfine structure due to Mn2+ ions in an environment close to octahedral symmetry whereas the resonance peak at geff ˜ 3.3 and geff ˜ 4.3 is attributed to the rhombic surroundings of the Mn2+ ions.