Shaaban M. Salem

Dielectric and Pyroelectric Properties of BaTiO3 Embedded in Li2B4O7 Glass Matrix

Glass sample with the composition 80 Li2B4O7–20 BaTiO3 (in mol%) was prepared by the conventional melt quenching technique. Amorphous and glassy characteristics of the sample were established via X-ray powder diffraction (XRD) and differential scanning calorimetry (DSC) respectively. The precipitated BaTiO3 nanocrystal phase embedded in the glass sample was identified by transmission electron microscopic (TEM) and infrared absorption spectroscopy. The phase transition (ferroelectric–paraelectric) in the present sample was established through the detailed studies of DSC, dielectric constant, dielectric loss, ac conductivity, dc conductivity and pyroelectric properties. The results demonstrate that the method presented may be an effective way to improvement of pyroelectric properties which is beneficial to the development of pyroelectric detectors.

Mössbauer Effect Study of Bi2O3. Na2O. B2O3. Fe2O3 Glass System

Sodium‐tetra‐borate host glass containing both bismuth and iron cations were prepared obeying the composition (Na2B4O7)0.75 (Fe2O3)0.25−x (Bi2O3)x [where x = 0.0, 0.05, 0.10, 0.15, 0.20, and 0.25 mol.%]. X‐ray diffraction indicated that all samples were in a homogeneous glassy phase. Mossbauer effect results showed that all iron ions appeared as Fe3+ ions occupying tetrahedral coordination state. The covalency of the Fe–O bond increased as bismuth oxide was gradually increased. IR measurements indicated the presence of some non‐bridging oxygens and confirmed that iron ions occupy the tetrahedral coordination state. It was found also that, as Bi2O3 was gradually increased both magnetic susceptibility and specific volume decreased, while both density and molar volume increased.