M. Elisa, C. Grigorescu, I. Vasiliu, M. Bulinski, V. Kuncser, D. Predoi, G. Filoti, A. Meghea, N. Eftimie, C. Onose M. Giurginca, Optical characterization of the phosphate glasses containing transition ion pairs, Optical and Quantum Electronics, 39/4-6 (2007) 523-531

Title: Optical characterization of the phosphate glasses containing transition ion pairs, Optical and Quantum Electronics

Abstract: The paper deals with optical and electronic properties of the aluminophosphate glasses containing Fe-Mn and Fe-Cr ion pairs in different concentration. The influence of the mixed alkali ions over the electronic properties has been investigated. The optical behavior (optical transmission) of the glass samples has been studied by UV-VIS spectroscopy and the refractive index dependency on wavelength has been discussed. The transmission spectra show features specific for the doping transition ions (TM), revealing different oxidation states of iron (Fe2+/Fe3+), manganese (Mn2+/Mn3+) and chromium (Cr3+/Cr6+) in the vitreous network. Mossbauer spectroscopy offers information regarding the TM oxidation states, redox processes and the iron coordination symmetry in the vitreous network. In the case of Fe-Mn doped glasses, the percentage of Fe2+ is about 40% and a doubled iron content leads to an increasing of Fe2+ percentage up to 53%. The replacing of lithium ions by natrium ions (mixed alkali effect) provides an increasing of the Fe2+ percentage up to 56%. The occurrence of the tetrahedral or octahedral symmetry of Fe(2+)supercript stop ions bonded by O2- ions depends on the transition ion nature and Li+/Na+ ratio. Infrared absorption spectra of the pair transition ions-doped aluminophosphate glasses reveal optical phonons specific for the phosphate glass matrix.

Key words: phosphate glass; transition ions; UV-VIS; IR and Mossbauer spectroscopy