EPR of Cu2+ ions in B2O3-SrO glasses

Structural details of strontium borate glasses were investigated by means of Cu2+ ions electron paramagnetic resonance (EPR). Glasses of the system 2B(2)O(3).SrO containing CuO over a wide concentration range by controlled doping, were explored to reveal the composition's influence upon the valence state and distribution of copper ions in the glass matrix. The hyperfine structure resolved in both parallel and perpendicular band of the spectrum within a broad concentration range proves the great structural stability of the vitreous matrix when copper ions accumulate during the doping process. Octahedral environments, axially distorted, of the Cu2+ ions were detected. No clusters of ions were evidenced. Mixed valence states of copper were revealed especially at high CuO content. The interactions involving Cu2+ ions are predominantly of dipole-dipole type.