Synthesis, characterization and dielectric properties of Ba1−x La x Ti1−x/4O3 powders and ceramics synthesized by sol–gel method
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In the present study polycrystalline Ba1−x La x Ti1−x/4O3 (x = 0.00, 0.015, 0.025, 0.035, 0.045 and 0.055) powders were synthesized using sol–gel route at 850 °C for 4 h. Calcined powders were sintered in air at 1300 °C for 6 h to make dense ceramics. XRD studies confirmed the tetragonal crystal structure of the x = 0.00–0.035 compositions at room temperature of the Ba1−x La x Ti1−x/4O3 ceramic samples. A cubic symmetry (Pm3m) was observed for the x > 0.035 compositions around room temperature. SEM studies showed that the average grain size was decreased with an increase in La content. The dielectric constant (ɛr) and dielectric loss (tan δ) of the Ba1−x La x Ti1−x/4O3 ceramics were investigated in the frequency regime (10 kHz–1 MHz). The highest magnitude of ɛr and tan δ around room temperature at 10 kHz was recorded for the x = 0.025 composition as 14,468 and 0.07, respectively. The Curie temperature (Tc) was shifted to low temperatures with an increase in La content. Complex impedance analysis confirmed the grain boundary and bulk contribution in the conduction mechanism for the x = 0.00 composition. The x ≥ 0.015 compositions showed only grain boundary contributions. The total resistance of sintered samples was decreased with an increase in temperature for the Ba1−x La x Ti1−x/4O3 ceramics, showing a typical ceramic behavior.
KeywordsBaTiO3 Barium Titanate Boundary Contribution BaTiO3 Ceramic Bulk Contribution
The authors acknowledge the financial support of Higher Education Commission of Pakistan under the 5000 Indigenous PhD Fellowship Program and International Research Support Initiative Program (IRSIP). The authors acknowledge the laboratory support extended by Prof. I. M. Reaney and his group, Electroceramic Laboratory, Department of Material Science and Engineering, University of Sheffield (UK).