الفهرس 
Aim of the work
In spectraOnly 14 pages are availabe for public view
 |  | from | 203 |  |  |
| | | from | 203 | | |
Abstract
Different groups of glasses in the systems Fe2O3-P2O5, PbO-P2O5 and Fe2O3-PbO-P2O5 have been prepared over a wide range of composition. The structure of these glasses was probed using the IR spectral analysis technique. In addition, some physical properties of the studied glasses such as density and electrical conductivity, were investigated.
The IR spectral analyses revealed that the structure of Fe2O3-P2O5 glasses consists of PO4 groups linked to Fe2+and Fe3+ ions in octahedral or tetrahedral coordination. Increasing Fe2O3 content increases the fraction of P-O- F2+ and P-O-F3+bonds, consequently the glass matrix strength increases.
The DC conductivity data were analyzed in terms of the small polaron hopping theory of Mott. The hopping regime between Fe ions was confirmed to be non-adiabatic in nature.
from the IR data of PbO-P2O5 glasses it was indicated that the short range order structure has been affected in two compositional regions. The first one is for glasses containing PbO < 50 mol%. In this range PbO enters the structure as a network modifier and the number of non bridging oxygen ions (NBOs) increases upon increasing PbO content. The second region is for glasses containing PbO >50 mol %, where PbO plays (in addition) the role of glass former .