الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 16 |  |  |
| | | from | 16 | | |
Abstract
The Sodium silicate, sodium borate and sodium phosphate become now of high interest because of their variants applications in both science and technology. Thus, the study of these glasses draws the interest of most solid-state physics and material science researchers.
Iron doped in silicate, borate and phosphate glasses have been prepared by conventional melt quenching technique
The glasses were prepared from chemically pure materials orthoboric acid (H3BO4) for B2O3, ammonium di-hydrogen phosphate (NH4H2PO4, 99%Winlab, LECESTERSHIRE, UK) was the source of P2O5 and sodium bicarbonate (NaHCO3) for Na2O, while SiO2 and Fe2O3 were added in the form of their oxides.
Appropriate amounts of the raw materials were thoroughly mixed and grinded in a pestle and mortar for half an hour. The prepared mixture was heated in the temperature range of 800-1200oC for 30 min until a bubble-free liquid was formed. The melt was then poured into a preheated graphite mould and annealed at a temperature of 300-400oC to avoid breaking of the sample through residual internal strain. The obtained samples were grinded and subsequently polished with cerium oxide. All the glasses had no visible bubbles in them, after that, the glasses were cut into sheets of 25×25×1 mm, and all the surfaces were well polished using 400 mesh ceria powder.
The density of the glasses was measured by the Archimedes method using xylene as the immersion liquid. The molar volume was calculated from the density data.
XRD technique was used to investigate and identify the structure of the prepared glasses which show that the amorphous phase while SEM technique was used to study the effect of successive gamma irradiation dose to the prepared samples.
Optical (UV-visible) absorption spectra of the prepared doped glasses were measured within the range (200 – 800 nm) using a double beam spectrophotometer (Type JASCO Corp. Model V – 570) with an estimated error of ± 0.5 %. All measurements were performed on the prepared samples as well as those γ – irradiated at different doses (0.5, 1.5 and 3 MRad).
Experimental optical absorption spectra of prepared glasses reveal that no characteristic bands were present in both ultra violet and visible region and exhibited only an UV cutoff extending from the beginning of the measurements up to 330 nm.
AC conductivity measurements were carried out and optical energy gap, urbach energy, activation energy, permittivity and dielectric loss were recorded .The electrical studies were repeated after subjecting the prepared glasses to successive gamma irradiation doses (5, 15 and 25 MRad).
EPR spectrometer is a physical technique designed to detect molecules with un-paired electron (free radical) which have a permanent magnetic – dipole moment (μ), and this magnetic – dipole moment arises from spinning motion of the electron about its axis and the motion of the electron in its orbital in atom or molecule in most cases the contribution to the magnetic moment from orbital motion is negligible in comparison to that from the spinning motion of the electron. The EPR signals are appeared due to the present of Fe3+.