Nickel ion- : A structural probe in BaO-Al2O3-P2O5 glass system by means of dielectric, spectroscopic and magnetic studies

Effect of alkaline earth modifier ion on the optical, magnetic and electrical properties of lithium nickel borate glasses

Alkali–magnesia silica glasses with lithium (74 SiO 2 , 16 Li 2 O, 10 MgO), sodium ((90 −  x ) SiO 2 , x Na 2 O, 10 MgO ( x =10, 15, 20, 25)), potassium ((90 −  x ) SiO 2 , x K 2 O, 10 MgO ( x =10, 15, 20, 25)) and caesium (74 SiO 2 , 16 Cs 2 O, 10 MgO) (all compositions given in mol%) doped with 02 mol% Fe 2 O 3 were studied by means of square-wave voltammetry Decreasing Na 2 O and K 2 O contents lead to an increase in the standard potentials of the Fe 3+ /Fe 2+ redox pair A comparison of the different alkali ions shows that the standard potentials increase from lithium to caesium The standard potentials, standard enthalpies and standard entropies of iron in the alkali–magnesia–silica glasses are compared with literature data of alkali–lime–silica glasses Empirical correlations enable a quantitative calculation of the standard potentials from the chemical composition

Thermodynamics of iron in alkali–magnesia–silica glasses

Optical absorption and thermoluminescence studies on LiF–Sb2O3–B2O3 glasses doped with Ni2+ ions

Diffusivities of polyvalent elements in glass melts

The redox behavior of Ni2+ ions in alkali silicate melts, xR2O · (1 - x)SiO2, (R = Na, K and Cs and x in the range 0.175 – 0.45), was investigated using linear sweep voltammetry and differential pulse polarography. The half-wave potential of Ni2+Ni0 depends on the alkali species and contents. It shifted to the positive side when the alkali species changed from sodium through potassium and cesium at a fixed ratio of alkali oxide to silica, indicating that NiO loses its thermodynamic stability in this order. Based on visible absorption spectra, it is shown that the Ni2+ ion exists in tetrahedral and octahedral coordinations in the alkali silicate glasses. The relative ratio of tetrahedral to octahedral species of Ni2+ also depends on the alkali species, and the content of the tetrahedral species of Ni2+ in potassium or cesium silicate is greater than that in sodium silicate. From these two results, it is assumed that, while NiO dissolves in the silicate melts as a weak base, some Ni2+ ions change into a tetrahedral coordination in a strongly basic solvent such as cesium silicate.

M. Shibata

Papers

Studies of NiO dissolved in alkali silicate melts based on redox potential and visible absorption spectra