High permittivity and low loss dielectric ceramics in the BaO–La2O3–TiO2–Ta2O5 system

Dielectric ceramics were synthesized and characterized in the BaO–La2O3–TiO2–Ta2O5 quaternary system for the three typical compositions: Ba3La3Ti5Ta5O30, Ba4La2Ti4Ta6O30 and Ba5LaTi3Ta7O30, which formed the filled tungsten-bronze structures. The present ceramics indicated high dielectric constant ε (127.7–148.1) and low dielectric loss tanδ (in the order of 10−4–10−3 at 1 MHz). Meanwhile, the temperature coefficient of dielectric constant τε varied from −728 to −1347 ppm/°C with increasing Ba and Ta and decreasing La and Ti concentration in the temperature range of 20–85 °C. The present ceramics are promising candidates for high-ε and low loss dielectric ceramics, and the suppression of τε should be the primary issue in the future work.