Abstract
Electric properties of lithium heptagermanate Li2Ge7O15 single crystal have been studied in AC external field (101–105 Hz) in the temperature range 300–700 K. It has been shown that below 500 K conductivity σ is determined by polarization processes whereas above this temperature charge transfer phenomena become dominant. It is assumed that at high temperatures conduction is determined by mobile interstitial lithium ions АLi. The spectra of complex impedance ρ* testify for hopping АLi conduction and accumulation of charge carriers near to blocking Pt electrodes.