Optical properties of Pr and Nd ions in a borate glass

A set of five borate glasses containing oxides of praseodymium and neodymium have been prepared with several relative molar ratios of Pr and Nd. FTIR measurements showed the presence of the B–O stretching mode in BO₄ tetrahedra at 900 cm^–1, as well as the B–Ô–B bending mode at 700 cm^–1 in the glasses. UV-visible absorption spectra were measured and found to be due to the 4f electronic transitions of the Pr and Nd ions. These absorption peaks were only weakly linked to their structural neighbourhoods, as evidenced by the compositionally scaled patterns showing very good agreement, in peak wavelengths, with the measured data in these glasses as well as in the equivalent glasses with phosphate as the host matrix. However, the intensities of Nd absorption peaks are observed to be enhanced by the presence of Pr ions in these glasses. Excitation at 445 nm of the luminescent states of Nd and Pr yielded emission data in the range 800 nm to 950 nm and lifetimes between 1·094 μs and 1·225 μs, indicating that the local structural environment of the rare earth ions does not greatly affect these states.