Structural, optical, and dielectric properties of the BaO-TiO2-P(2)O(5)glasses
Résumé
The glass compositions 20BaO-xTiO(2)-(80-x)P(2)O(5)with (x = 5, 10, and 20%mol) were elaborated by the conventional quenching method. These vitreous materials show a constant content of the barium oxide while the Ti/P ratio varies. They are characterized by X-ray diffraction in order to ascertain their amorphous nature. Density measurements are performed using diethyl orthophthalate as a medium liquid. It was found that their density and molar volume increases and reduces with TiO(2)content, respectively. Raman spectroscopic analysis is employed to characterize their structural approach. This technique revealed the occurrence of various structural units of phosphate in the glass-matrix, primarily pyrophosphates, and metaphosphates. The optical absorption study of glasses confirmed the existence of Ti(3+)ions in all the glassy samples, and it was found that the optical bandgap depends on the composition of the glass and reduces as the TiO(2)content increases. Glass-ceramics relatives to the glasses were obtained by performing heat treatments of the glasses. The crystallized phases are identified using X-ray diffraction (XRD). It was found that a glass-ceramic containing a ferroelectric BaTiO(3)phase is developed by transforming a glass composition (x = 20) to a crystalline phase. The electrical properties of the glass-ceramics are performed by impedance spectroscopy in the frequency range of 100 Hz to 1 MHz under various temperatures from 300 to 573 K. The glass-ceramic (GC) (x = 20) at room temperature has the highest dielectric constant epsilon(r) = 51.6 and lower dielectric loss Tan delta = 0.005, and it was found that the glass-ceramics are mixed conductors with both ionic and electronic conductivities. The obtained results are discussed according to the chemical composition of these materials.