研究目的

The objectives of the present work are (1) to prepare Dy3+-doped alkali fluoroborophosphate glasses by melt quenching technique, (2) to identify the different vibrational bands of the borate network in the prepared glasses, (3) to evaluate the predominant nature of covalent/ionic bonds of the prepared glasses from the absorption spectra and (4) to calculate the oscillator strengths and Judd–Ofelt parameters (X2, X4, X6) from the absorption energy levels and refractive index of the prepared glasses, (5) to study the luminescence characteristics of the 6F11/2 → 6H15/2 transition in the visible region and the 6H11/2 → 6H15/2 transition in the NIR region, (6) to calculate the radiative parameters of the desired transitions, (7) to determine the stimulated emission cross section of the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions. (8) To study the characteristics of the emission colors through CIE 1931 chromaticity diagram and finally (9) to measure the decay curves of the 4F9/2 energy level and also to discuss and report the possibility of energy transfer between Dy3+–Dy3+ ions in the prepared glasses.

研究成果

The Dy3+-doped alkali fluoroborophosphate glasses have been prepared by conventional melt quenching technique and the characteristics for their structural and optical properties were studied through XRD, absorption and luminescence spectral measurements and decay curves analysis. The amorphous nature of the prepared glass was confirmed by XRD spectral measurements. FTIR spectra have been studied for all the glasses and the types of bonds found are present in the prepared glasses. The negative d values indicate the ionic nature of the Dy3+–O bond in the prepared glasses. The oscillator strengths and the JO intensity parameters Xk (k = 2, 4, 6) have been calculated, and it follows the trend as X2 > X6 > X4 uniformly for all the prepared glasses. Among three intensity parameters in all the alkali fluoroborophosphate glasses, particularly BPZKDY1.0 glass, there is higher magnitude in X2 parameter (8.1186) which is attributed to higher covalancy and asymmetry. From the radiative properties, of all the studied glasses, BPZKDY1.0 glass possesses large value of stimulated emission cross section (3.3102) and radiative branching ratios for the 4F9/2 → 6H13/2 transition. Hence, it is suggested that these glasses are useful for the potential laser materials. The decay curve analysis reveal the non-exponential behavior for the 4F9/2 level, which indicates that the dipole–dipole ion interaction dominates in the Dy3+–Dy3+ ions. The x, y coordinates of the prepared glasses are found to be in the white light region of the CIE diagram and thus suggest their suitability for white light applications.

研究不足

The hygroscopic nature of borophosphate glass matrices hampered its applications and had therefore stimulated further study in incorporating network modifiers using heavy metals and alkali metals.