title: Structural and optical properties of lead-boro-tellurrite glasses induced by gamma-ray.
abstract: Spectrophotometric studies of lead borotellurite glasses were carried out before and after gamma irradiation exposure. The increasing peak on the TeO(4) bi-pyramidal arrangement and TeO(3+1) (or distorted TeO(4)) is due to augmentation of irradiation dose which is attributed to an increase in degree of disorder of the amorphous phase. The structures of lead tellurate contain Pb(3)TeO(6) consisting of TeO(3) trigonal pyramid connected by PbO(4) tetragonal forming a three-dimensional network. The decrease of glass rigidity is due to irradiation process which is supported by the XRD diffractograms results. The decreasing values of absorption edge indicate that red shift effect occur after irradiation processes. A shift in the optical absorption edge attributed to an increase of the conjugation length. The values of optical band gap, E(opt) were calculated and found to be dependent on the glass composition and radiation exposure. Generally, an increase and decrease in Urbach's energy can be considered as being due to an increase in defects within  glass network.
authors: School of Physics, Universiti Sains Malaysia, 11800 Minden, Pulau Pinang, Malaysia. halimah@science.upm.edu.my.
authors: Iskandar Shahrim
authors: IS
authors: Mustafa
authors: Halimah Mohamed
authors: HM
authors: Kamari
authors: Wan Mohd Daud Wan
authors: WM
authors: Yusoff
authors: Sidek Abdul
authors: SA
authors: Aziz
authors: Azhar Abdul
authors: AA
authors: Rahman