title: Structural investigations on sodium-lead borophosphate glasses doped with vanadyl ions.
abstract: Electron paramagnetic resonance (EPR), optical absorption, and FT-IR spectra of vanadyl ions in the sodium-lead borophosphate (Na(2)O-PbO-B(2)O(3)-P(2)O(5)) (SLBP) glass system have been studied. EPR spectra of all the glass samples exhibit resonance signals characteristic of VO(2+) ions. The spin Hamiltonian parameters g and A are found to be independent of the V(2)O(5) content and temperature. The values of the spin Hamiltonian parameters indicate that the VO(2+) ions in SLBP glasses are present in octahedral sites with tetragonal compression. The population difference between Zeeman levels (N) is calculated as a function of temperature for an SLBP glass sample containing 1.0 mol % VO(2+) ions. From the EPR data, the paramagnetic susceptibility (χ) is calculated at different temperatures, and the Curie constant (C) is calculated from the 1/χ versus T graph. The optical absorption spectra of the glass samples show two absorption bands, and they are attributed to V(3+) and V(4+) ions. The optical band gap energy (E(opt)) and Urbach energy (ΔE) are calculated from their ultraviolet absorption edges. It is observed that, as the vanadium ion concentration increases, E(opt) decreases and ΔE increases. The study of the IR absorption spectrum depicts the presence of BO(3), BO(4), PO(3), PO(4), and VO(5) structural units.
authors.affiliation: University Science Instrumentation Center, Sri Venkateswara University, Tirupati, India.
authors.forename: K
authors.initials: K
authors.lastname: Srinivasulu
authors.forename: I
authors.initials: I
authors.lastname: Omkaram
authors.forename: H
authors.initials: H
authors.lastname: Obeid
authors.forename: A Suresh
authors.initials: AS
authors.lastname: Kumar
authors.forename: J L
authors.initials: JL
authors.lastname: Rao
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D001896:Boron Compounds / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D005898:Glass; D007477:Ions; D007854:Lead / Q000737:chemistry*; D055096:Optical Devices; D010087:Oxides / Q000737:chemistry*; D017553:Phosphorus Compounds / Q000737:chemistry*; D017670:Sodium Compounds / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D013816:Thermodynamics; D014638:Vanadates / Q000737:chemistry*
chemical_list: D001672:Biocompatible Materials; D001896:Boron Compounds; D007477:Ions; D010087:Oxides; D017553:Phosphorus Compounds; D017670:Sodium Compounds; D007854:Lead; C096707:sodium oxide; D014638:Vanadates; C042168:boron oxide; C047365:lead oxide; C012500:phosphorus pentoxide