Structure and electrical conductivity relaxation studies of Nb2O5-doped B2O3–Bi2O3–LiF glasses

摘要: Glasses with composition (70 − x) B2O3·15Bi2O3·15LiF·xNb2O5 x = 0–1.0 mol% were prepared by conventional glass-melting technique. The molar volume Vm values decrease and the glass transition temperatures Tg increase of Nb2O5 content up to 0.2 mol%, which indicates that Nb5+ ions act as a former. Beyond increases decreases, suggests modifier. FTIR spectra suggest are incorporated into network NbO6 octahedra, substituting BO4 groups. temperature dependence dc conductivity follows Greaves variable range hopping model below 454 K, small polaron at >454 K. σdc, σac dielectric constant (e) activation energy for conduction ΔEdc increasing whereas decreases beyond mol%. impedance spectroscopy shows single semicircle or arcs indicate only ionic mechanism. electric modulus formalism relaxation is occurring different frequencies exhibit temperature-independent dynamical process. (FWHM) normalized in suggesting distribution times associated charge carriers Li+ F− network.