Spectroscopic and electrical investigations of copper ions in PbO–GeO2 glasses

Abstract Small concentrations of copper oxide doped PbO–GeO 2 glasses were prepared by melt quenching technique. The characteristics of the samples were analyzed by X-ray diffraction, scanning electron microscopy and DSC techniques. The analysis of XRD spectra established the disorderly nature of the glass composition and no specialized crystalline species are observed. The surface morphology of the glass samples has also been systematically investigated by scanning electron microscopy. The optical absorption and ESR spectral studies have revealed probable presence of Cu 2+ ions that act as modifiers and induce non-bridging oxygens (NBO’s) in the glass network. The observed decrease in the optical band gap with the increase in the concentration of CuO is attributed to the gradual reduction of Cu 2+ ions into Cu + ions. The presence of GeO 4 , GeO 6 , Ge–O–Ge and PbO 4 structural blocks has been verified by means of IR spectral bands. The overall inference of optical, ESR and IR studies is that the Cu 2+ ions might have changed from ionic environment to covalent environment progressively. The dielectric parameters viz. , dielectric constant, e′ , loss, tan δ , and ac conductivity, σ ac , were studied by varying frequency and temperature. The values of e′ and loss tan δ were enhanced where as σ ac , values are dipped. It is proved that the more is the number of Cu 2+ ions in the samples, the higher are the values of dielectric parameters.