MAGNETIZATION AND XPS STUDIES OF THE REDOX STATE OF COPPER IN SIO2-NA2O-CUO GLASSES

Sodium copper silicate glasses of composition (SiO2)(0.70-x) (Na2O)(0. 30)(CuO)(x) where 0 less than or equal to x less than or equal to 0.20 were studied by magnetisation and x-ray photoelectron spectroscopy (X PS) techniques. The M versus H data at different temperatures collapse s to a single curve in the M versus H/T representation for all the gla ss compositions studied, indicating that the magnetic ion-ion interact ion is weak and that Cu2+ behaves paramagnetically in these glasses. T he M versus H curves have been fitted with a Brillouin function by mai ntaining the number of magnetic ions as the fitting parameter and dedu cing the number of Cu2+ ions in each glass sample from the best fit to the experimental data. XPS has also been used to determine the number of Cu2+ ions in the glass samples by deconvoluting the Cu2p(3/2) phot oelectron spectra into contributions from Cu2+ ions detected by XPS is much lower than that obtained from bulk magnetic measurements. A poss ible origin of this difference is indicated.