Luminescence characteristics of Dy3+ doped borofluoro-phosphate glasses for white emission applications

Abstract

The present work reports structural and luminescence studies on Dy3+ doped borofluorophosphate (BFPDY) glasses prepared with the chemical composition of (40-x)B2O3 + 30P2O5 + 10ZnF + 10K2O + 10BaO + xDy2O3, where x = 0.1, 0.2, 0.5 and 1 mol% by melt quenching technique. The structural and optical properties of the prepared glasses were analysed by means of XRD, FTIR, UV-V is absorption spectroscopy and photoluminescence emission and excitation spectra. XRD results confirm the amorphous nature of glass and FTIR studies reveals the presence of various stretching and bending vibrations of different structural units within the sample. The optical absorption spectrum has been recorded at room temperature and different absorption transitions were obtained and it is found that the transition via 6H15/2→6P7/2 is more prominent. From the absorption spectrum, optical band gap energy, nephelauxetic ratio (β) and the bonding parameter (δ) were determined. Excitation spectrum was recorded in the region 300-500 nm by monitoring emission at 572 nm and characteristic excitation bands were observed. The band at 348 nm arising through the transition 6H15/2→6P7/2 shows maximum intensity. The photoluminescence spectra of the fitted glasses have been recorded at an excitation wavelength of 348 nm and the spectra contain two intense emission bands in the blue (483 nm) and yellow (572 nm) regions and a weak band in the red region (663 nm). Concentration dependent variations in emission intensities were analysed. It is observed from the emission spectra that the luminescence intensity increases with the increase in Dy3+ ion content up to 0.5 mol% beyond that it decreases due to luminescence quenching. The Y/B intensity ratio by varying the concentration of Dy2O3 is also studied. The emission intensity were characterized through Commission International d'Eclairage (CIE) 1931 chromaticity diagram to explore its suitability for white light emission applications.