Abstract
Glasses having the composition, [(70-x) mol% B<sub>2</sub>O<sub>3</sub>- x mol% Bi<sub>2</sub>O<sub>3</sub>- 10 mol% BaO- 20 mol% Na<sub>2</sub>O, where 0≤ x ≤20], have been prepared by the melt quenching method. Density, molar volume, infrared analysis, optical parameters and Electrical properties have been thoroughly investigated. It was found that, both density and molar volume increased with the gradual replacement of B<sub>2</sub>O<sub>3</sub> by Bi<sub>2</sub>O<sub>3</sub> and the comparison between their experimental and empirical values confirm the amorphous nature and the random structure of all samples. The obtained infrared results indicated that different structural borate groups appeared such as BO4 units (in di-, tri- and penta-borate groups) and BO<sub>3</sub> units (in meta- and ortho-borate chains). Also, both BiO<sub>3</sub> and BiO<sub>6</sub> are present in all Bi doped glasses, and the BiO<sub>3</sub> / BiO<sub>6</sub> ratio appeared to be approximately stable as Bi<sub>2</sub>O<sub>3</sub> was increased to 15 mol%, then it showed a jump increase when BiO<sub>3</sub> reached 20 mol%. The optical band gap energy and cut-off wavelength increased with the increase of Bi<sub>2</sub>O<sub>3</sub> while Urbach energy decreased. On the other hand, the electrical conductivity decreased as Bi<sub>2</sub>O<sub>3</sub> was gradually replaced by B<sub>2</sub>O<sub>3</sub>, while the activation energy increased and all samples exhibit semi-conductors behavior and the values of the exponent factor decreased gradually with temperature, which is compatible with the correlated barrier hopping conduction mechanism.
Highlights
The study of heavy metal doped various glasses appeared of high interest
The visual examination of the prepared samples showed that all samples are transparent and reflecting the amorphous nature and randomness character, density (ρ) and molar volume (Vm) values were obtained in order to confirm the amorphous nature for all samples
It is observed that, the empirical density values are absolutely higher than those obtained experimentally. This can be attributed to the high density value of Bi2O3 (8.9 g/cm3) which is much greater than that of B2O3 (2.56 g/cm3)
Summary
The study of heavy metal doped various glasses appeared of high interest These glasses exhibit different important physical and chemical properties (such as: high refractive index, high IR transparency, high density, good shielding parameters for ionizing radiation...etc.) [1]. It is well known that, boron atoms in borate glasses are usually coordinated either to three or four oxygen atoms forming [BO3] or [BO4] structural units, depending on the concentration of the added modifier cations. The properties of borate glasses modified with alkali oxide show a nonlinear behavior when alkali oxide was gradually increased This departure from linearity is termed as boron anomaly phenomenon. The effect of the gradual replacing of B2O3 by Bi2O3 on the density, molar volume, electrical transport properties and optical parameters, of the prepared solid glasses has been thoroughly studied. The obtained glasses were subjected to FTIR spectral analysis, in order to get information about the internal structural groups in the glass networks
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