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

Dielectric ac measurements in the frequency range of similar to 1 mHz-1 MHz were performed on beta-Ta2O5 samples made by chemical vapor deposition. A method of estimating the dielectric constant and the dc conductivity from t he dielectric response was developed. The high-frequency dielectric constan t was found to be 25.84 with no detectable temperature dependence and the d c conductivity due to protons had an activation energy of about 0.4 eV in t he studied temperature range (from 24 to 90 degrees C). Evidence for the co nduction mechanism being protonic rather then electronic was found from iso thermal transient ionic current (ITIC) measurements. The ITIC recordings co uld also determine conduction parameters, such as proton mobility, number o f charge carriers, and dc conductivity. (C) 1999 American Institute of Phys ics. [S0021-8979(99)03304-6].