الفهرس 
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Abstract
Glasses with composition: [XBi2O3-(83-X) B2O3-15Na2O-2MnO2] with X=0, 5, 10, 20 and 25 mol. % were investigated aiming to study the effect of replacement of B2O3 with Bi2O3 on the physical properties of the prepared samples. The samples were prepared using conventional melt-quenching technique. The amorphous nature of the prepared samples was confirmed by X-ray diffraction (XRD) using (nickel- filtered Cu-Kα radiation, Philips PW3050/60 diffractometer).The density (ρ) was measured by applying conventional Archimedes method with toluene as the immersion liquid (ρ0 = 0.868 g/cm3) and an electric single pan balance of 10-3 g sensitivity. It is observed that the density increases with increasing Bi2O3 content. The increase in the density can be due to the introducing of heavy element Bi (atomic mass 208.98) on the base of light element B (atomic mass 10.811) and the transformation of BO4 structure units with smaller volume into BO3 units with larger volume. Also the molar volume (VM) increases with increasing Bi2O3 content. Such unexpected results can be attributed to the formation of non- bridging oxygen (NBO) and expands (opens up) the structure of the prepared samples. Mn-ion parameters such as Mn-ion concentration (N), interionic distance (ri) and field strength (F) have been calculated. The oxygen packing density (OPD) which is a measure of the tightness of packing of the oxide network was calculated. It is found that its values decrease with increasing Bi2O3 content, which indicates that the glass network becomes less tightly packed and the degree of disorder increases with increasing Bi2O3 content. The electronic polarizability and the optical basicity have been calculated on the basis of the electronegativities of the consisting elements. The effect of Bi2O3 on the structural units of the glass was investigated by IR spectroscopy indicating the presence of [BO3], [BO4] and [BiO6] structural units. Deconvolutions of IR spectra were used to calculate the ratio N4. The obtained data revel that N4
Abstract
decreases by increasing Bi2O3 content which is consistent with the other obtained data. This can be accounted for by considering that the introducing of Bi (atomic mass 208.98) on the base of B (atomic mass 10.811) will lead to the increasing of density. However, the increase of NBO leads to open structure i.e. increase the molar volume. The above two arguments are responsible for the behavior of the density and the molar volume. Absorption and transmission spectra in the wavelength region (190-1100 nm) of the samples were obtained and analyzed. The optical band gap energy (Eg) and the width of the tail (ΔEe) of the localized states in the band gap have been estimated. The refractive index was calculated using approximate equation. The sample of composition [25Bi2O3-58 B2O3-15Na2O-2MnO2] was chosen, and CuO was added to the batch by different concentration 2, 3 and4% CuO for obtaining the filtering effect. The optical spectra of the Cu doped samples were measured and studied.