The B2O3/SrO ratio influence on the structural and magnetic properties of the CuO-B2O3-SrO glasses

Glasses from the xCuO.(100-x)[yB(2)O(3).SrO] system with 0 <= x <= 30 mol% and y=1, 2 were prepared and studied by spectroscopic (FT-IR, Raman, EPR) and magnetic susceptibility measurements. Both, FT-IR and Raman spectroscopy have revealed changes in the glasses structure when the composition was modified. The FT-IR data revealed the presence of tri-, tetra-, pyro- and penta-borate groups in structures of both series of glasses. Supplementary, ortho-borate groups were detected for y=1. For the same x value, highest values of BO4/BO3 ratio were observed for samples with y=2. Raman data confirm the FTIR results and complete the information about these glasses, by detecting chain type metaborate groups. The EPR spectra show the tendency of the Cu2+ ions to insert in these two glass matrix networks in axially distorted octahedral environments. Both EPR and magnetic measurements point out the simultaneous presence, for x <= 10 mol%, of Cu2+ and Cu+ species. The Curie behaviour of magnetic susceptibility indicates the presence of Cu2+ ions isolated and/or dipolar coupled.