Improvement of the dielectric properties of Ta2O5 through substitution with Al2O3

For bulk ceramic materials, small substitutions of Al2O3 in Ta2O5 are shown to cause a moderate enhancement of the dielectric constant. For compositions near 0.95Ta2O5–0.05Al2O3, the temperature coefficient of the dielectric constant at 20 °C dramatically decreases, from more than 200 ppm/°C for pure Ta2O5 to less than 20 ppm/°C. The quality factors (Q) at 1 MHz, are 2000–5000. Measurements to 14 GHz at 20 °C show that the dielectric constant is maintained to microwave frequencies, with a Q of ∼600 at 5 GHz.