Impurity effects on the critical behaviour of the electrical resistance of binary liquid mixtures

Abstract

The electrical resistance of the binary liquid system cyclohexane + acetic anhydride is measured, in the critical region, both in the pure mixture and when the mixture is doped with small amounts (≈ 100 ppm) of H₂O/D₂O impurities. T_c was approached to about t = 3×10^-6 where t = (T -T_c)/T_c . The critical exponent b ≈ 0·35 in the fit of the resistance data to the equation dR/dT~t^-b does not seem to be affected appreciably by the impurities. There is a sign reversal of dR/dt in the non-critical region. Binary liquid systems seem to violate the universality of the critical resistivity.