Electrical and elastic properties of binary lead chloroborate glasses
H A Silim; G El-Damrawi; Y M Moustafa; A K Hassan; H A Silim; Dept. of Phys., Mansoura Univ., Egypt; G El-Damrawi; Dept. of Phys., Mansoura Univ., Egypt; Y M Moustafa; Dept. of Phys., Mansoura Univ., Egypt; A K Hassan; Dept. of Phys., Mansoura Univ., Egypt
Журнал:
Journal of Physics: Condensed Matter
Дата:
1994-08-01
Аннотация:
Various comparative experiments on xPbCl<sub>2</sub>-(100-x)B<sub>2</sub>O<sub>3</sub>(20<or=*<or=45 mol%) glasses reveal that the PbCl<sub>2</sub> does not enter the B-O network, but is inserted into interstices or voids in the glassy matrix. However, the network becomes systematically weakened and expanded with increasing PbCl<sub>2</sub> concentration; this is observed as a decrease in T<sub>g</sub>, and an increase of both the molar volume and thermal expansion coefficient. The electrical conductivity measurements of these glasses demonstrated a marked enhancement in the ionic conductivity ( sigma ). The maximum enhancement in sigma is by eight orders of magnitude as PbCl<sub>2</sub> replaces B<sub>2</sub>O<sub>3</sub>(45 mol%). The drastic increase in sigma leads us to suggest that the Cl<sup>-</sup> ions form additional migration pathways for Pb<sup>2+</sup> ions, which are important for the conduction mechanisms. In addition, the activation energy associated with jumping Pb<sup>2+</sup> ions decreases with increasing PbCl<sub>2</sub> content; this indicates that jumps of the Pb<sup>2+</sup> ions in the vicinity of the Cl<sup>-</sup> ions are relatively easy.
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