Rare earth elements (REE) are widely used in today's technology – for example, in lasers based on REE-doped crystals or glasses. REE the most frequently used in lasers are lanthanides. This is due to a large variety of their 4f configurations, which leads to a wide range of fluorescent states and wavelengths [1]. Telecommunication technologies have also benefited from the use of those elements. Oxidized and ceramic glasses doped with REE found their application in WDM technology (Wavelength Division Multiplexing), and thus a series of optical amplifiers based on REE were created. Furthermore, those elements introduced into phosphors help adjust white LED's light to the range of human vision. Therefore, they gained worldwide interest.
The atomic structure of lanthanides (group that includes considered Sm, Eu) is characterized by unfilled 4f shell and external shells that screen 4f shell from the influence from outside. This feature is responsible for remarkable optical properties of lanthanides. Optical spectra of those elements exhibit sharp lines characteristic for transition within the 4f shell, known as forbidden transitions. In real terms it means that they may occur, but with low probability, according to Judd-Ofelt Theory. Aforementioned screening of 4f shell by outer shells results in protection of optically active electrons from the influence of crystal field and as a result, REE ion's spectrum in a solid can be similar to that of a free ion spectrum [2].
The research carried out very recently in our group has shown that it is possible to prepare REE-doped glassy materials with that are characterized by strong radial transitions [3]. Therefore, it is worth to investigate different glassy matrices in order to find those of the best mechanical and chemical resistance. In our studies, CaAlBO3F2 glassy matrices doped with 1 wt% Eu2O3 and Sm2O3 were successfully prepared by a melt-quenching method. Substrates were melted for 15 min at 1300 °C.
