Measurement scheme to detect α relaxation time of glass-forming liquid

A measurement scheme for detecting the alpha relaxation time (tau) of glass-forming liquid is proposed, which is based on the measured ionic conductivity of the liquid doped with probing ions by low- and middle-frequency dielectric spectroscopy and according to the Nernst-Einstein, Stokes-Einstein, and Maxwell equations. The obtained tau values of glycerol and propylene carbonate by the scheme are consistent with those obtained by traditional dielectric spectroscopy, which confirms its reliability and accuracy. Moreover, the tau of 1,2-propanediol in a larger temperature range is compared with existing data.