Spectroscopic studies of lead arsenate glasses doped with nickel oxide

Lead arsenate glasses containing different concentrations of NiO ranging from 0 to 1 mol% (in steps of 0.2 mol%) were prepared. The samples were characterized by X-ray diffraction and differential thermal analysis. A number of studies viz., optical absorption, thermoluminescence, magnetic susceptibilities and IR spectra, have been carried out on these glasses. The bands observed in the optical absorption spectra of the glasses have been analyzed using Tanabe–Sugano diagrams for d8 ion; the analysis indicates the presence of Ni2+ ions in both tetrahedral and octahedral positions. The increase in the concentration of NiO in the glass matrix shows a gradual transformation of nickel ions from tetrahedral positions to octahedral positions in the glass network. The thermoluminescence light output of the X-ray irradiated glasses has exhibited a glow peak at 353 K (with increasing intensity with an increase in the concentration of NiO) in addition to the conventional peak due to the recombination of electron–hole centers; this glow peak is identified due to 3T2 → 3A2 emission transition of octahedral Ni2+ ions. The value of the magnetic moment evaluated from the measured magnetic susceptibility show a decreasing trend from 3.84 to 3.10 μB with the increase in the concentration of NiO. All these studies indicate an increasing presence of octahedral (lasing) Ni2+ ions in these glasses with the increase in the concentration of NiO.