Effect of heat treatment on the absorption bands of Nd3+ ions in fluoroindate glass and error calculation in experimental oscillator strength and intensity parameters

• Get more bands to achieve better results in the process of adjustments to the numerical calculations.
• Show that any intensity parameter can take negative values, not only the Ω2.
• Show the importance of taking into account all the parameters included in the standard Judd–Ofelt model, for sets of intensity parameters with positive values.
• Recommend methods to obtain parameters of positive intensity, which is not excluded from the calculations, most intense bands, such as hypersensitivity.
• Associate somehow the matrix elements with their respective intensity parameters.

For this work, a fluoroindate glass doped with Nd+3 ions was prepared. To define the heating temperatures of the sample, the glass transition temperature (Tg) and crystallization temperature Tx, in order to define the range of vitreous stability (Tg−Tx) were obtained through differential scanning calorimetric (DSC) measurements (thermograms). The absorption spectrum of the sample at room temperature in the spectral range between 300 and 1800 nm was measured. To analyze the effect of heating, the sample was heated at 390 °C for 15 h and the absorption spectrum was measured. To obtain the best absorption spectra (the largest number of possible points) for both the normal sample (NTT) and that heated to 390 °C (TT390), the spectrophotometer was set to its highest definition (0.1 nm) in the measured range. With the points obtained for each of the bands and through a program in MATLAB, the best fit to the respective theoretical curves was obtained for each band and used as a reference in the calculation of error of the respective experimental oscillator strength for each of the bands. The information thus obtained allows us to evaluate the effect of including all parameters (odd and even) in the calculation, which were taken into account in the original Judd–Ofelt model.