Structural and enhanced dielectric properties of Li-doped BT elaborated by the sol-gel method

• Published in: Journal of sol-gel science and technology 2024-10, Vol.112 (1), p.182-201
• Main Authors: Aychaoui, Fouad El, Basset, Abdelhalim El, Naji, Mohamed, Bouzid, Mohammed, Rjeb, Abdelilah, Hajji, Lahoucine, Ababou, Yahya
• Format: Article
• Language: English
• Subjects: Ceramics; Chemistry and Materials Science; Composites; Composition; Conduction cooling; Conduction heating; Dielectric loss; Dielectric properties; Doping; Electrical properties; Electrical resistivity; Free electrons; Glass; Grain boundaries; Grain size; Infrared spectroscopy; Inorganic Chemistry; Lithium; Materials Science; Nanotechnology; Natural Materials; Optical and Electronic Materials; Original Paper; Phase transitions; Raman spectroscopy; Room temperature; Sol-gel processes; Spectrum analysis; Temperature dependence; Transition temperature
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-024-06525-3

In this paper, we studied the effect of lithium doping on the structural, microstructural, dielectric, and electrical properties of Ba 1-x Li x TiO 3-δ (BTLx) ceramics prepared via the sol-gel method, with x = 0, 0.01, 0.03, 0.05, 0.07 and 0.09. The results obtained from Rietveld refinement of X-ray diffraction, infrared spectroscopy, and Raman spectroscopy show that all the samples crystallize in the tetragonal phase. Dielectric measurements show that increasing the lithium doping rate results in lower dielectric losses (from 0.04 for x = 0 to 0.008 for x = 0.09 at room temperature) and lower transition temperature Tm for compositions with x ≤ 0.07. The phase transition diffusivity parameter γ varies between 1 and 1.39, showing that our samples exhibit a diffuse phase transition but far from relaxor behavior. Complex impedance spectroscopy indicates that the grain boundary resistance of the materials is predominant in the electrical behavior of the materials. The activation energy Ea was calculated at 10 kHz by linear fitting of the temperature dependence of conductivity using the Arrhenius formula. The obtained values indicate that conduction for compositions with 0 ≤ x ≤ 0.05 occurs through free electrons originating from the ionization of oxygen vacancies, while for the compositions with x = 0.07 and 0.09, the predominant conduction mechanism is ionic conduction. Graphical Abstract Highlights Using the Sol-Gel method to reduce sintering temperature, and decrease average grain size. Minimization of dielectric losses through Li doping for applications in capacitors, and energy storage devices. High stability of the dielectric properties of BTLx materials over a wide range of frequencies.