Commentary on ‘Nonlinear impedance as possible result of ion–polaron interaction in Cu2O–Al2O3–SiO2 glass’

Recently, Barczynski [J. Non-Cryst. Solids 356 (2010) 1962] published nonlinear impedance spectra of a copper aluminosilicate glass which conducts both ions and polarons. Nonlinearities in the impedance signal were detected at electric field strengths as low as 1 V/mm. In order to rationalize this finding, a qualitative picture was suggested with coupled movements of ions and polarons in the bulk of the glass. A closer inspection of the nonlinear spectra reveals, however, that the nonlinearities occur exclusively in the electrode polarisation regime of the impedance spectra and are therefore not related to bulk charge transport.