Optical absorption and photoluminescence properties of Dy3+ doped heavy metal borate glasses – Effect of modifier oxides

Abstract

The present paper aims at reporting the optical absorption and emission properties of Dy3+ doped alkali (Li, Na, K) and mixed alkali (Li–Na, Li–K, Na–K) heavy metal borate glasses. For these glasses X-ray diffraction (XRD), differential scanning calorimetry (DSC), optical absorption, emission and lifetime decay measurements were carried out. Glass transition temperatures are obtained from the DSC spectra. Judd–Ofelt theory has been used to derive the spectral intensities (f), Judd–Ofelt intensity parameters (Ω2, Ω4 and Ω6) and certain radiative properties. Using the Judd–Ofelt intensity parameters, radiative lifetimes (τR), branching ratios (β), integrated absorption cross-sections (Σ) and emission cross-sections (σP) were obtained. The variations in these parameters with the variation of glass matrix are discussed in detail. The decay lifetime of the 4F9/2 level has been measured from the decay profiles and compared with calculated lifetimes. From the emission spectra, chromacity color coordinates are calculated and indicated the white light emission for potassium glass matrices. It was observed that among various glass matrices, potassium glass matrix has exhibited large emission cross-section for 6F9/2→6H13/2 transition.