The Soret effect in non-stoichiometric copper(I)-oxide (cuprite, Cu2−δO) was studied experimentally by means of non-isothermal solid state galvanic cells (thermo-cells) under different boundary conditions. At high temperatures and high O activities, Cu migrated down the temperature gradient and a gradient in the non-stoichiometry was established under stationary conditions. The heat of transport of Cu metal was determined to be Q*Cu ≈ 180kJ/mol at 1000C and an O activity of log aO2 = −2.95. This result agreed with recent theoretical simulations of the heat of transport of atoms migrating via a vacancy mechanism. These predict a positive sign of the heat of transport and a considerably larger value than the activation energy for the atomic jumps.

On the Soret Effect in Binary Non-Stoichiometric Oxides - Kinetic Demixing of Cuprite in a Temperature Gradient. H.Timm, J.Janek: Solid State Ionics, 2005, 176[11-12], 1131-43