Influence of alkaline earths on EPR spectra of lithium borate glasses doped with Fe (III) ions

Abstract

Lithium borate glasses containing Fe (III) transition metal ion having composition 15RO-25Li2O-59B2O3-1Fe2O3 (where R= CaO, SrO and BaO) are synthesized via melt quench route. These glasses were characterized using X-ray diffraction (XRD). Electron paramagnetic resonance spectra of prepared glasses have been studied. The recorded spectra mainly consists of an intense resonance signals at g ∼ 4.282 and also at g ∼ 2.0032 along with a shoulder in the region of g ∼ 8.033 which is a characteristic of iron ions in the (3+) valence state in all the studied glasses. The number of spins participating in resonance (N) and its paramagnetic susceptibilities (χ) have also been evaluated. The spin concentration and the paramagnetic susceptibility at g = 2.0032 and at g = 4.282 increase by the substitution of alkaline earths from CaO to BaO respectively. The peak-to-peak line width ΔB for the resonance lines at g ≈ 4.282 and at g ≈ 2.0032 and the line intensity of the resonance centered at g ≈ 4.282 and at g ≈ 2.0032 have been evaluated. This EPR spectra has been analyzed in the light of different oxidation states of iron ions in order to understand the influence of alkaline earths as modifier oxide on the structure of glass matrix.