Gamma-induced absorption spectra as a new method for RE-ion environment study in fluorophosphate glasses

Doped fluorophosphate glasses based on pseudo-binary system: barium metaphosphate Ba(PO3)2- usovite MgCaSrBaAl2F14, are studied by means of fluorescence, induced ESR and optical absorption spectra. Doping the glass, containing 5 and 7 mol% Ba(PO3)2 with TbF3 and EuF3 results in drastic changes of color and paramagnetic center numbers correspondingly. Post-irradiation process results in separation of the spectra analyzed into groups in dependence of Tb3+ ion concentration. The crucial concentration, dividing two concentration ranges is not more than 0.02 mol%. It is supposed that the local environment of Tb3+ ion doped up to concentration mentioned is preferably phosphate. Estimates of Eu3+ ion concentration that have preferably phosphate groupings in their environment result from concentration dependence of PO42− centers and produce the value of approximately 0.01 mol%. Close values of two crucial concentrations is interpreted in terms of doped ion segregation model.