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Formation of the plateau conductivity spectrum revealed by electrode dependence in Na β-alumina, O. Kamishima (Setsunan Univ.)

This study examines the formation of the plateau conductivity spectrum in Na b-alumina bycomparing reversible (Na-Hg amalgam) and ion-blocking (Au) electrodes. AC impedance was measured from 10¹ to 5 × 10⁶ Hz at 0.5 V_RMS between 217K and 352K. Both electrode types exhibit a ∝ f ^0.13 dependence at low temperatures, but with the Na-Hg electrode the low-frequency response evolves near 0 °C into a frequency-independent plateau, which is absent with Au electrodes. These results indicate that the observed plateau can arise from an electrodemediated DC background rather than an intrinsic Drude-type AC response of mobile ions, underscoring the importance of electrode conditions.