Improvement of the dielectric properties of Ta2O5 through substitution with Al2O3

Abstract

For bulk ceramic materials, small substitutions of ${\mathrm{Al}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{3}}$ in ${\mathrm{Ta}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{5}}$ are shown to cause a moderate enhancement of the dielectric constant. For compositions near 0.95${\mathrm{Ta}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{5}}$ –0.05${\mathrm{Al}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{3}},$ the temperature coefficient of the dielectric constant at 20 °C dramatically decreases, from more than 200 ppm/°C for pure ${\mathrm{Ta}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{5}}$ to less than 20 ppm/°C. The quality factors $\mathrm{(Q)}$ 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.