A frequency response and transient current study of β-Ta2O5: Methods of estimating the dielectric constant, direct current conductivity, and ion mobility

Dielectric ac measurements in the frequency range of ∼1 mHz–1 MHz were performed on $\mathrm{\beta -}{\mathrm{Ta}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{5}}$ samples made by chemical vapor deposition. A method of estimating the dielectric constant and the dc conductivity from the dielectric response was developed. The high-frequency dielectric constant was found to be 25.84 with no detectable temperature dependence and the dc conductivity due to protons had an activation energy of about 0.4 eV in the studied temperature range (from 24 to 90 °C). Evidence for the conduction mechanism being protonic rather then electronic was found from isothermal transient ionic current (ITIC) measurements. The ITIC recordings could also determine conduction parameters, such as proton mobility, number of charge carriers, and dc conductivity.